TREATMENT OF CANCER

Abstract: The present invention relates to a method for the treatment of tumours, the method comprising inhibiting angiogenesis in a subject in need thereof characterised in that angiogenesis is inhibited by administering to the subject an agent which inhibits induction of EGR, an agent which decreases expression of EGR or an agent which decreases the nuclear accumulation or activity of EGR. The present invention also relates to a method of screening for agents which inhibits angiogenesis.

Description: Treatment of cancer FIELD OF THE INVENTION The present invention relates to compositions and methods for the treatment of cancer. BACKGROUND OF THE INVENTION Cancer Cancer accounted for over half a million deaths in the United States in 1998 alone, or approximately 23 % of all deaths (Landis et al., 1998). Only cardiovascular disease consistently claims more lives (Cotran et al., 1999). There is growing evidence that the cellular and molecular mechanisms underlying tumour growth involves more than just tumour cell proliferation and migration. Importantly, tumour growth and metastasis are critically dependent upon ongoing angiogenesis, the process of new blood vessel formation (Crystal, 1999). Angiogenesis (also known as neovascularisation) is mediated by the migration and proliferation of vascular endothelial cells that sprout from existing blood vessels to form a growing network of microvessels that supply growing tumours with vital nutrients. Primary solid tumours cannot grow beyond 1-2 mm diameter without active angiogenesis (Harris, 1998). Human HepG2 hepatocellular carcinoma cells have been used as a model cancer cell line for the assessment of anti-neoplastic drugs (Yang et al., 1997). These cells basally and inducibly express the immediately-early gene and transcriptional regulator, early growth response factor-1 (EGR-1) (Kosaki et al., 1995). Early Growth Response Protein (EGR-1) Early growth response factor-1 (EGR-1, also known as Egr-1, NGFI-A, zif268, krox24 and TIS8) is the product of an immediate early gene and a prototypical member of the zinc finger family of transcriptional regulators (Gashler et al., 1995). Egr-1 binds to the promoters of a spectrum of genes implicated in the pathogenesis of atherosclerosis and restenosis. These include the platelet-derived growth factor (PDGF) A-chain (Khachigian et al., 1995), PDGF-B (Khachigian et al., 1996), transforming growth factor^ (Liu et al, 1996,1998), fibroblast growth factor-2 (FGF-2) (Hu et al., 1994; Biesiada et al., 1996), membrane type 1 matrix metalloproteinase (Haas et al., 1999), tissue factor (Cui et al., 1996) and intercellular adhesion molecule-1 (Malzman et al., 1996). EGR-1 has also been localised to endothelial cells and smooth muscle cells in human atherosclerotic plaques (McCaffrey et al., 2000). Suppression of Egr-1 gene induction using sequence-specific catalytic DNA inhibits intimal thickening in the rat carotid artery following balloon angioplasty (Santiago et al., 1999a). DNAzvmes In human gene therapy, antisense nucleic acid technology has been one of the major tools of choice to inactivate genes whose expression causes disease and is thus undesirable. The anti-sense approach employs a nucleic acid molecule that is complementary to, and thereby hybridizes with, an mRNA molecule encoding an undesirable gene. Such hybridization leads to the inhibition of gene expression. Anti-sense technology suffers from certain drawbacks. Anti-sense hybridization results in the formation of a DNA/target mRNA heteroduplex. This heteroduplex serves as a substrate for RNAse H-mediated degradation of the target mRNA component. Here, the DNA anti-sense molecule serves in a passive manner, in that it merely facilitates the required cleavage by endogenous RNAse H enzyme. This dependence on RNAse H confers limitations on the design of anti-sense molecules regarding their chemistry and ability to form stable heteroduplexes with their target mRNA's. Anti- sense DNA molecules also suffer from problems associated with non-specific activity and, at higher concentrations, even toxicity. An example of an alternative mechanism of antisense inhibition of target mRNA expression is steric inhibition of movement of the translational apparatus along the mRNA. As an alternative to anti-sense molecules, catalytic nucleic acid molecules have shown promise as therapeutic agents for suppressing gene expression, and are widely discussed in the literature (Haseloff (1988); Breaker (1994); Koizumi (1989); Otsuka; Kashani-Sabet (1992); Raillard (1996); and Carmi (1996)). Thus, unlike a conventional anti-sense molecule, a catalytic nucleic acid molecule functions by actually cleaving its target mRNA molecule instead of merely binding to it. Catalytic nucleic acid molecules can only cleave a target nucleic acid sequence if that target sequence meets certain minimum requirements. The target sequence must be complementary to the hybridizing arms of the catalytic nucleic acid, and the target must contain a specific sequence at the site of cleavage. Catalytic RNA molecules ("ribozymes") are well documented (Haseloff (1988); Symonds (1992); and Sun (1997)), and have been shown to be capable of cleaving both RNA (Haseloff (1988)) and DNA (Raillard (1996)) molecules. Indeed, the development of in vitro selection and evolution techniques has made it possible to obtain novel ribozymes against a known substrate, using either random variants of a known ribozyme or random-sequence RNA as a starting point (Pan (1992); Tsang (1994); and Breaker (1994)). Ribozymes, however, are highly susceptible to enzymatic hydrolysis within the cells where they are intended to perform their function. This in turn limits their pharmaceutical applications. Recently, a new class of catalytic molecules called "DNAzymes" was created (Breaker and Joyce (1995); Santoro (1997)). DNAzymes are single- stranded, and cleave both RNA (Breaker (1994); Santoro (1997)) and DNA (Carmi (1996)). A general model for the DNAzyme has been proposed, and is known as the "10-23" model. DNAzymes following the "10-23" model, also referred to simply as "10-23 DNAzymes", have a catalytic domain of 15 deoxyribonucleotides, flanked by two substrate-recognition domains of seven to nine deoxyribonucleotides each. In vitro analyses show that this type of DNAzyme can effectively cleave its substrate RNA at purine:pyrimidine junctions under physiological conditions (Santoro (1997)). DNAzymes show promise as therapeutic agents. However, DNAzyme success against a disease caused by the presence of a known mRNA molecule is not predictable. This unpredictability is due, in part, to two factors. First, certain mRNA secondary structures can impede a DNAzyme's ability to bind to and cleave its target mRNA. Second, the uptake of a DNAzyme by cells expressing the target mRNA may not be efficient enough to permit therapeutically meaningful results. SUMMARY OF THE INVENTION The present inventors have established that EGR-1 is critical in vascular endothelial cell replication and migration and that DNA-based, sequence- specific catalytic molecules targeting EGR-1 inhibit the growth of malignant cells in culture. These findings show that inhibitors of EGR or related EGR family members are useful in the treatment of tumours and that two separate mechanisms of action may involved. Specifically, inhibitors of EGR family members may inhibit tumour growth indirectly by inhibiting angiogenesis and/or directly by blocking the EGR family member in tumour cells. When used herein the term "EGR" refers to a member of the EGR family. Members of the EGR family are described in Gashler et al., 1995 and include EGR-1 to EGR-4. It is currently preferred that the EGR family member is EGR-1. Accordingly, in a first aspect the present invention provides a method for the treatment of a tumour, the method comprising administering to a subject in need thereof an agent which inhibits induction of EGR, an agent which decreases expression of EGR or an agent which decreases the nuclear accumulation or activity of EGR. In a second aspect, the present invention provides a method for inhibiting the growth or proliferation of a tumour cell, the method comprising contacting a tumour cell with an agent which inhibits induction of EGR, an agent which decreases expression of EGR or an agent which decreases the nuclear accumulation or activity of EGR. In a third aspect, the present invention provides a tumour cell which has been transformed by introducing into the cell a nucleic acid molecule, the nucleic acid molecule comprising or encoding (i) an agent which inhibits induction of EGR, (ii) an agent which decreases expression of EGR, or (iii) an agent which decreases the nuclear accumulation or activity of EGR. In a fourth aspect, the present invention provides a method of screening for an agent which inhibits angiogenesis, the method comprising testing a putative agent for the ability to inhibit induction of EGR, decrease expression of EGR or decrease the nuclear accumulation or activity of EGR. In a preferred embodiment of the present invention the agent is selected from the group consisting of an EGR antisense oligonucleotide, a ribozyme targeted against EGR, a ssDNA targeted against EGR dsDNA such that the ssDNA forms a triplex with the EGR-1 ds DNA, and a DNAzyme targeted against EGR. BRIEF DESCRIPTION OF THE FIGURES Figure 1. Insulin stimulates Egr-1-dependent gene expression in vascular endothelial cells. Growth-arrested bovine aortic endothelial cells previously transfected with pEBSl foscat using FuGENE6 were incubated with D-glucose (5-30 mM), insulin (100 nM) or FGF-2 (25 ng/ml) as indicated for 24 h prior to preparation of cell lysates. CAT activity was normalized to the concentration of protein in the lysates. Figure 2. Insulin-induced DNA synthesis in aortic endothelial cells is blocked by antisense oligonucleotides targeting Egr-1. A, Insulin stimulates DNA synthesis. Growth-arrested endothelial cells were incubated with insulin (100 nM or 500 nM) or FBS (2.5%) for 18 h prior to Η-thymidine pulse for a further 6 h. B, Antisense Egr-1 oligonucleotides inhibit insulin-inducible DNA synthesis. Endothelial cells were incubated with 0.8 μM of either AS2, AS2C or E3 prior to exposure to insulin (500 nM or 1000 nM) for 18 h and 3 H-thymidine pulse for 6 h. C, Dose-dependent inhibition of insulin-inducible DNA synthesis. DNA synthesis stimulated by insulin (500 nM) was assessed in endothelial cells incubated with 0.4 μM or 0.8 μM of AS2 or AS2C. TCA-precipitable Η- thymidine incorporation into DNA was assessed using a β-scintillation counter. Figure 3. Insulin-inducible DNA synthesis in cultured aortic endothelial cells is MEK/ERK-dependent. Growth quiescent endothelial cells were preincubated for 2 h with either PD98059 (10 μM or 30 μM), SB202190 (100 nM or 500 nM) or wortmannin (300 nM or 1000 nM) prior to the addition of insulin (500 nM) for 18 h and 3 H- thymidine pulse. TCA-precipitable 3 H- thymidine incorporation into DNA was assessed using a β-scintillation counter. Figure 4. Wound repair after endothelial injury is potentiated by insulin in an Egr-1-dependent manner. The population of cells in the denuded zone 3 d after injury in the various groups was quantitated and presented histodiagrammatically. Figure 5. Human microvascular endothelial cell proliferation is inhibited by DNA enzymes targeting human EGR-1. SV40-transformed HMEC-1 cells were grown in MCDB 131 medium with EGF (10 ng/ml) and hydrocortisone (1 μg ml) supplements and 10% FBS. Forty-eight hours after incubation in serum-free medium without supplements, the cells were fransfected with the indicated DNA enzyme (0.4 μM) and transfected again 72 h after the change of medium, when 10% serum was added. The cells were quantitated by Coulter counter, 24 h after the addition of serum. Figure 6. Sequence of NGFI-A DNAzyme (ED5), its scrambled control (ED5SCR) and 23 nt synthetic rat substrate. The translational start site is underlined. Figure 7. NGFI-A DNAzyme inhibits the induction of NGFI-A protein by serum (FBS). Western blot analysis was performed using antibodies to NGFI-A, Spl or c-Fos. The Coomassie Blue stained gel demonstrates that uniform amounts of protein were loaded per lane. The sequence of EDC is 5'-CGC CAT TAG GCT AGC TAC AAC GAC CTA GTG AT-3' (SEQ ID NO:l); 3' T is inverted. SFM denotes serum-free medium. Figure 8. SMC proliferation is inhibited by NGFI-A DNAzyme. a, Assessment of total cell numbers by Coulter counter. Growth-arrested SMCs that had been exposed to serum and/or DNAzyme for 3 days were trypsinized followed by quantitation of the suspension. The sequence of AS2 is 5'-CTT GGC CGC TGC CAT-3' (SEQ ID NO:2) . b, Proportion of cells incorporating Trypan Blue after exposure to serum and/or DNAzyme. Cells were stained incubated in 0.2% (w:v) Trypan Blue at 22 C C for 5 min prior to quantitation by hemocytometer in a blind manner, c, Effect of ED5 on pup SMC proliferation. Growth-arrested WKY12-22 cells exposed to serum and or DNAzyme for 3 days were resuspended and numbers were quantitated by Coulter counter. Data is representative of 2 independent experiments performed in triplicate. The mean and standard errors of the mean are indicated in the figure. * indicates P<0.05 (Student's paired t- test) as compared to control (FBS alone). Figure 9. NGFI-A DNAzyme inhibition of neointima formation in the rat carotid artery. A neointima was achieved 18 days after permanent ligation of the right common carotid artery. DNAzyme (500 μg) or vehicle alone was applied adventitially at the time of ligation and again after 3 days. Sequence-specific inhibition of neointima formation. Neointimal and medial areas of 5 consecutive sections per rat (5 rats per group) taken at 250 μm intervals from the point of ligation were determined digitally and expressed as a ratio per group. The mean and standard errors of the mean are indicated by the ordinate axis. * denotes P<0.05 as compared to the Lig, Lig+Veh or Lig+Veh+ED5SCR groups using the Wilcoxen rank sum test for unpaired data. Lig denotes ligation, Veh denotes vehicle. Figure 10. HepG2 cell proliferation is inhibited by 0.75μM of DNAzyme DzA. Assessment of total cell numbers by Coulter counter. Growth-arrested cells that had been exposed to serum and/or DNAzyme for 3 days were trypsinized followed by quantitation of the suspension. The sequence of DzA is 5'- caggggacaGGCTAGCTACAACGAcgttgcggg (SEQ ID NO:3). DETAILED DESCRIPTION OF THE INVENTION In a first aspect the present invention provides a method for the treatment of a tumour, the method comprising administering to a subject in need thereof an agent which inhibits induction of an EGR, an agent which decreases expression of an EGR or an agent which decreases the nuclear accumulation or activity of an EGR. The method of the first aspect may involve indiract inhibition of tumour growth by inhibiting angiogenesis and/or direct inhibition by blocking EGR in tumour cells. In a preferred embodiment of the first aspect, the tumour is a solid tumour. The tumour may be selected from, without being limited to, a prostate tumour, a hepatocellular carcinoma, a skin carcinoma or a breast tumour. As will be recognised by those skilled in this field there are a number means by which the method of the present invention may be achieved. In a preferred embodiment of the present invention, the EGR is EGR-1. In one embodiment, the method is achieved by targeting the EGR gene directly using triple helix (triplex) methods in which a ssDNA molecule can bind to the dsDNA and prevent transcription. In another embodiment, the method is achieved by inhibiting transcription of the EGR gene using nucleic acid transcriptional decoys. Linear sequences can be designed that form a partial intramolecular duplex which encodes a binding site for a defined transcriptional factor. Evidence suggests that EGR transcription is dependent upon the binding of Spl, API or serum response factors to the promoter region. It is envisaged that inhibition of this binding of one or more of these transcription factors would inhibit transcription of the EGR gene. In another embodiment, the method is achieved by inhibiting translation of the EGR mRNA using synthetic antisense DNA molecules that do not act as a substrate for RNase H and act by sterically blocking gene expression. In another embodiment, the method is achieved by inhibiting translation of the EGR mRNA by destabilising the mRNA using synthetic antisense DNA molecules that act by directing the RNase H-mediated degradation of the EGR mRNA present in the heteroduplex formed between the antisense DNA and mRNA. In one preferrede embodiment of the present invention, the antisense oligonucleotide has a sequence selected from the group consisting of (i) ACA CTT TTG TCT GCT (SEQ ID NO:4), and (ii) CTT GGC CGC TGC CAT (SEQ ID NO:2). In another embodiment, the method is achieved by inhibiting translation of the EGR mRNA by cleavage of the mRNA by sequence-specific hammerhead ribozymes and derivatives of the hammerhead ribozyme such as the Minizymes or Mini-ribozymes or where the ribozyme is derived from: (i) the hairpin ribozyme, (ii) the Tetrahymena Group I intron, (iii) the Hepatitis Delta Viroid ribozyme or (iv) the Neurospera ribozyme. It will be appreciated by those skilled in the art that the composition of the ribozyme may be; (i) made entirely of RNA, (ii) made of RNA and DNA bases, or (iii) made of RNA or DNA and modified bases, sugars and backbones Within the context of the present invention, the ribozyme may also be either; (i) entirely synthetic or (ii) contained within a transcript from a gene delivered within a virus- derived vector, expression plasmid, a synthetic gene, homologously or heterologously integrated into the patients genome or delivered into cells ex vivo, prior to reintroduction of the cells of the patient, using one of the above methods. In another embodiment, the method is achieved by inhibition of the ability of the EGR gene to bind to its target DNA by expression of an antisense EGR-1 mRNA. In another embodiment, the method is achieved by inhibition of EGR activity as a transcription factor using transcriptional decoy methods. In another embodiment, the method is achieved by inhibition of the ability of the EGR gene to bind to its target DNA by drugs that have preference for GC rich sequences. Such drugs include nogalamycin, hedamycin and chromomycin A3 (Chiang et al J. Biol. Chem 1996; 271:23999). In a preferred embodiment, the method is achieved by cleavage of EGR mRNA by a sequence-specific DNAzyme. In a further preferred embodiment, the DNAzyme comprises (i) a catalytic domain which cleaves mRNA at a purine:pyrimidine cleavage site; (ii) a first binding domain contiguous with the 5' end of the catalytic domain; and (iii) a second binding domain contiguous with the 3' end of the catalytic domain, wherein the binding domains are sufficiently complementary to two regions immediately flanking a purine:pyrimidine cleavage site within the region of EGR mRNA corresponding to nucleotides 168 to 332 as shown in SEQ ID NO: 15, such that the DNAzyme cleaves the EGR mRNA. As used herein, "DNAzyme" means a DNA molecule that specifically recognizes and cleaves a distinct target nucleic acid sequence, which may be either DNA or RNA. In a preferred embodiment, the binding domains of the DNAzyme are complementary to the regions immediately flanking the cleavage site. It will be appreciated by those skilled in the art, however, that strict complementarity may not be required for the DNAzyme to bind to and cleave the EGR mRNA. The binding domain lengths (also referred to herein as "arm lengths") can be of any permutation, and can be the same or different. In a preferred embodiment, the binding domain lengths are at least 6 nucleotides. Preferably, both binding domains have a combined total length of at least 14 nucleotides. Various permutations in the length of the two binding domains, such as 7+ 7, 8 + 8 and 9+9, are envisioned. The catalytic domain of a DNAzyme of the present invention may be any suitable catalytic domain. Examples of suitable catalytic domains are described in Santoro and Joyce, 1997 and U.S. Patent No. 5,807,718. In a preferred embodiment, the catalytic domain has the nucleotide sequence GGCTAGCTACAACGA (SEQ ID NO:5). Within the context of the present invention, preferred cleavage sites within the region of EGR mRNA corresponding to nucleotides 168 to 332 are as follows: (i) the GU site corresponding to nucleotides 198-199; (ii) the GU site corresponding to nucleotides 200-201 (iii) the GU site corresponding to nucleotides 264-265 (iv) the AU site corresponding to nucleotides 271-272 (v) the AU site corresponding to nucleotides 292-293 (vi) the AU site corresponding to nucleotides 301-302 (vii) the GU site corresponding to nucleotides 303-304 and (viii) the AU site corresponding to nucleotides 316-317. In a further preferred embodiment, the DNAzyme has a sequence selected from: (i) 5'-caggggacaGGCTAGCTACAACGAcgttgcggg (SEQ ID NO:3) targets GU (bp 198, 199); arms hybridise to bp 189-207 (ii) 5'-tgcaggggaGGCTAGCTACAACGAaccgttgcg (SEQ ID NO:6) targets GU (bp 200, 201); arms hybridise to bp 191-209 (iii) 5'-catcctggaGGCTAGCTACAACGAgagcaggct (SEQ ID NO:7) targets GU (bp 264, 265); arms hybridise to bp 255-273 (iv) 5'-ccgcggccaGGCTAGCTACAACGAcctggacga (SEQ ID NO:8) targets AU (bp 271, 272); arms hybridise to bp 262-280 (v) 5'-ccgctgccaGGCTAGCTACAACGAcccggacgt (SEQ ID NO:9) targets AU (bp 271, 272); arms hybridise to bp 262-280 (vi) 5'-gcggggacaGGCTAGCTACAACGAcagctgcat (SEQ ID NO:10) targets AU (bp 301, 302); arms hybridise to bp 292-310 (vii) 5'-cagcggggaGGCTAGCTACAACGAatcagctgc (SEQ ID NO:ll) targets GU (bp 303, 304); arms hybridise to bp 294-312 (viii) 5'-ggtcagagaGGCTAGCTACAACGActgcagcgg (SEQ ID NO:12) targets AU (bp 316, 317); arms hybridise to bp 307-325. In a particularly preferred embodiment, the DNAzyme targets the the GU site corresponding to nucleotides 198-199, the AU site corresponding to nucleotides 271-272 or the AU site corresponding to nucleotides 301-302. In a further preferred embodiment, the DNAzyme has the sequence: 5'-caggggacaGGCTAGCTACAACGAcgttgcggg (SEQ ID NO:3), 5'-gcggggacaGGCTAGCTACAACGAcagctgcat (SEQ ID NO:10), 5'-ccgcggccaGGCTAGCTACAACGAcctggacga (SEQ ID NO:8) or 5'-ccgctgccaGGCTAGCTACAACGAcccggacgt (SEQ ID NO:9). In applying DNAzyme-based treatments, it is preferable that the DNAzymes be as stable as possible against degradation in the intra-cellular milieu. One means of accomplishing this is by incorporating a 3'-3' inversion at one or more termini of the DNAzyme. More specifically, a 3'-3' inversion (also referred to herein simply as an "inversion") means the covalent phosphate bonding between the 3' carbons of the terminal nucleotide and its adjacent nucleotide. This type of bonding is opposed to the normal phosphate bonding between the 3' and 5' carbons of adjacent nucleotides, hence the term "inversion". Accordingly, in a preferred embodiment, the 3'- end nucleotide residue is inverted in the building domain contiguous with the 3' end of the catalytic domain. In addition to inversions, the instant DNAzymes may contain modified nucleotides. Modified nucleotides include, for example, N3'-P5' phosphoramidate linkages, and peptide-nucleic acid linkages. These are well known in the art. In a particularly preferred embodiment, the DNAzyme includes an inverted T at the 3' position. Although the subject may be any animal or human, it is preferred that the subject is a human. Within the context of the present invention, the EGR inhibitory agents may be administered either alone or in combination with one or more additional anti-cancer agents which will be known to a person skilled in the art. Administration of the inhibitory agents may be effected or performed using any of the various methods and delivery systems known to those skilled in the art. The administering can be performed, for example, intravenously, orally, via implant, transmucosally,. transdermally, topically, intramuscularly, subcutaneously or extracorporeally. In addition, the instant pharmaceutical compositions ideally contain one or more routinely used pharmaceutically acceptable carriers. Such carriers are well known to those skilled in the art. The following delivery systems, which employ a number of routinely used carriers, are only representative of the many embodiments envisioned for administering the instant composition. In one embodiment the delivery vehicle contains Mg 2+ or other cation(s) to serve as co-factor(s) for efficient DNAzyme bioactivity. Transdermal delivery systems include patches, gels, tapes and creams, and can contain excipients such as solubilizers, permeation enhancers (e.g., fatty acids, fatty acid esters, fatty alcohols and amino acids), hydrophilic polymers (e.g., polycarbophil and polyvinylpyrolidone), and adhesives and tackifiers (e.g., polyisobutylenes, silicone-based adhesives, acrylates and polybutene). Transmucosal delivery systems include patches, tablets, suppositories, pessaries, gels and creams, and can contain excipients such as solubilizers and enhancers (e.g., propylene glycol, bile salts and amino acids), and other vehicles (e.g., polyethylene glycol, fatty acid esters and derivatives, and hydrophilic polymers such as hydroxypropylmethylcellulose and hyaluronic acid). Oral delivery systems include tablets and capsules. These can contain excipients such as binders (e.g., hydroxypropylmethylcellulose, polyvinyl pyrilodone, other cellulosic materials and starch), diluents (e.g., lactose and other sugars, starch, dicalcium phosphate and cellulosic materials), disintegrating agents (e.g., starch polymers and cellulosic materials) and lubricating agents (e.g., stearates and talc). Solutions, suspensions and powders for reconstitutable delivery systems include vehicles such as suspending agents (e.g., gums, zanthans, cellulosics and sugars), humectants (e.g., sorbitol), solubilizers (e.g., ethanol, water, PEG and propylene glycol), surfactants (e.g., sodium lauryl sulfate, Spans, Tweens, and cetyl pyridine), preservatives and antioxidants (e.g., parabens, vitamins E and C, and ascorbic acid), anti-caking agents, coating agents, and chelating agents (e.g., EDTA). Topical delivery systems include, for example, gels and solutions, and can contain excipients such as solubilizers, permeation enhancers (e.g., fatty acids, fatty acid esters, fatty alcohols and amino acids), and hydrophilic polymers (e.g., polycarbophil and polyvinylpyrolidone). In the preferred embodiment, the pharmaceutically acceptable carrier is a liposome or a biodegradable polymer. Examples of carriers which can be used in this invention include the following: (1) Fugeneδ ® (Roche); (2) SUPERFECT ® (Qiagen); (3) Lipofectamine 2000 ® (GIBCO BRL); (4) CellFectin, 1:1.5 (M/M) liposome formulation of the cationic lipid N,NI,NII,NIII- tetramethyl-N,NI,NII,NIII-tetrapalmitylspermine and dioleoyl phosphatidyl- ethanolamine (DOPE)(GIBCO BRL); (5) Cytofectin GSV, 2:1 (M/M) liposome formulation of a cationic lipid and DOPE (Glen Research); (6) DOTAP (N-[l- (2,3-dioleoyloxy)-N,N,N-trimethyl-ammoniummethylsulfate) (Boehringer Manheim); and (7) Lipofectamine, 3:1 (M/M) liposome formulation of the polycationic lipid DOSPA and the neutral lipid DOPE (GIBCO BRL). In a preferred embodiment, the agent is injected into or proximal the solid tumour. Injectable drug delivery systems include solutions, suspensions, gels, microspheres and polymeric injectables, and can comprise excipients such as solubility-altering agents (e.g., ethanol, propylene glycol and sucrose) and polymers (e.g., polycaprylactones and PLGA's). Implantable systems include rods and discs, and can contain excipients such as PLGA and polycaprylactone. Delivery of the nucleic acid agents described may also be achieved via one or more, of the following non-limiting examples of vehicles: (a) liposomes and liposome-protein conjugates and mixtures; (b) non-liposomal lipid and cationic lipid formulations; (c) activated dendrimer formulations; (d) within polymer formulations such pluronic gels or within ethylene vinyl acetate coploymer (EVAc). The polymer may be delivered intra-luminally; (e) within a viral-liposome complex, such as Sendai virus; or (f) as a peptide-DNA conjugate. Determining the prophylactically effective dose of the instant pharmaceutical composition can be done based on animal data using routine computational methods. In one embodiment, the prophylactically effective does contains between about 0.1 mg and about 1 g of the instant DNAzyme. In another embodiment, the prophylactically effective dose contains between about 1 mg and about 100 mg of the instant DNAzyme. In a further embodiment, the prophylactically effective does contains between about 10 mg and about 50 mg of the instant DNAzyme. In yet a further embodiment, the prophylactically effective does contains about 25 mg of the instant DNAzyme. It is also envisaged that nucleic acid agents targeting EGR may be administered by ex vivo transfection of cell suspensions, thereby inhibiting tumour growth, differentiation and/or metastasis. In a second aspect, the present invention provides a method for inhibiting the growth or proliferation of a tumour cell, the method comprising contacting a tumour cell with an agent which inhibits induction of EGR, an agent which decreases expression of EGR or an agent which decreases the nuclear accumulation or activity of EGR. In a third aspect, the present invention provides a tumour cell which has been transformed by introducing into the cell a nucleic acid molecule, the nucleic acid molecule comprising or encoding (i) an agent which inhibits induction of EGR, (ii) an agent which decreases expression of EGR, or (iii) an agent which decreases the nuclear accumulation or activity of EGR. In a preferred embodiment of the third and fourth aspects, the agent is selected from the group consisting of an EGR antisense oligonucleotide or mRNA, a sequence-specific ribozyme targeted against EGR, a ssDNA targeted against EGR dsDNA and a sequence specific DNAzyme targeted against EGR. In a fourth aspect, the present invention provides a method of screening for an agent which inhibits angiogenesis, the method comprising testing a putative agent for the ability to inhibit induction of EGR, decrease expression of EGR or decrease the nuclear accumulation or activity of EGR. The putative agent may be tested for the ability to inhibit EGR by any suitable means. For example, the test may involve contacting a cell which expresses EGR with the putative agent and monitoring the production of EGR mRNA (by, for example, Northern blot analysis) or EGR protein (by, for example, immunohistochemical analysis or Western blot analysis). Other suitable tests will be known to those skilled in the art. For reference, Table 1 below sets forth a comparison between the DNA sequences of mouse, rat and human EGR-1. Table 1 Mouse,. Rat and Human EGR-1 Symbol comparison table: GenRunData:pileupdna . cmp CompCheck: 6876 Gap eight: 5.000 GapLengthWeight: 0.300 EGRlalign.msf MSF: 4388 Type: N April 7, 1998 12:07 Check: 5107 Name: mouseEGRl Len : 4388 Check: 8340 Weight: 1.00 (SEQ ID NO:13) Name: ratEGRl Len: 4388 Check: 8587 Weight: 1.00 (SEQ ID NO:14) Name: humanEGRl Len: 4388 Check: 8180 Weight: 1.00 (SEQIDNO:15) NB. THIS IS RAT NGFI-A numbering 1 50 mouseEgrl ratNGFIA CCGCGGAGCC TCAGCTCTAC GCGCCTGGCG CCCTCCCTAC GCGGGCGTCC humanEGRl 51 100 mouseEGRl ratEGRl CCGACTCCCG CGCGCGTTCA GGCTCCGGGT TGGGAACCAA GGAGGGGGAG humanEGRl 101 150 mouseEGRl ratEGRl GGTGGGTGCG CCGACCCGGA AACACCATAT AAGGAGCAGG AAGGATCCCC humanEGRl 151 200 mouseEGRl ratEGRl CGCCGGAACA GACCTTATTT GGGCAGCGCC TTATATGGAG TGGCCCAATA humanEGRl 201 250 mouseEGRl ratEGRl TGGCCCTGCC GCTTCCGGCT CTGGGAGGAG GGGCGAACGG GGGTTGGGGC humanEGRl 251 300 mouseEGRl ratEGRl GGGGGCAAGC TGGGAACTCC AGGAGCCTAG CCCGGGAGGC CACTGCCGCT humanEGRl 301 350 mouseEGRl ratEGRl GTTCCAATAC TAGGCTTTCC AGGAGCCTGA GCGCTCAGGG TGCCGGAGCC humanEGRl 351 400 mouseEGRl ratEGRl GGTCGCAGGG TGGAAGCGCC CACCGCTCTT GGATGGGAGG TCTTCACGTC humanEGRl 401 450 mouseEGRl ratEGRl ACTCCGGGTC CTCCCGGTCG GTCCTTCCAT ATTAGGGCTT CCTGCTTCCC humanEGRl 451 500 mouseEGRl ratEGRl ATATATGGCC ATGTACGTCA CGGCGGAGGC GGGCCCGTGC TGTTTCAGAC humanEGRl 501 550 mouseEGRl ratEGRl CCTTGAAATA GAGGCCGATT CGGGGAGTCG CGAGAGATCC CAGCGCGCAG humanEGRl CCGCAG 551 600 mouseEGRl GGGGA GCCGCCGCCG CGATTCGCCG CCGCCGCCAG CTTCCGCCGC ratEGRl AACTTGGGGA GCCGCCGCCG CGATTCGCCG CCGCCGCCAG CTTCCGCCGC humanEGRl AACTTGGGGA GCCGCCGCCG CCATCCGCCG CCGCAGCCAG CTTCCGCCGC 601 650 mouseEGRl CGCAAGATCG GCCCCTGCCC CAGCCTCCGC GGCAGCCCTG CGTCCACCAC ratEGRl CGCAAGATCG GCCCCTGCCC CAGCCTCCGC GGCAGCCCTG CGTCCACCAC humanEGRl CGCAGGACCG GCCCCTGCCC CAGCCTCCGC AGCCGCGGCG CGTCCACGCC 651 700 mouseEGRl GGGCCGCGGC TACCGCCAGC CTGGGGGCCC ACCTACACTC CCCGCAGTGT ratEGRl GGGCCGCGGC CACCGCCAGC CTGGGGGCCC ACCTACACTC CCCGCAGTGT humanEGRl CGCCCGCGCC CAGGGCGAGT CGGGGTCGCC GCCTGCACGC TTCTCAGTGT 701 750 mouseEGRl GCCCCTGCAC CCCGCATGTA ACCCGGCCAA CCCCCGGCGA GTGTGCCCTC ratEGRl GCCCCTGCAC CCCGCATGTA ACCCGGCCAA CATCCGGCGA GTGTGCCCTC humanEGRl TCCCC.GCGC CCCGCATGTA ACCCGGCCAG GCCCCCGCAA CGGTGTCCCC 751 800 mouseEGRl AGTAGCTTCG GCCCCGGGCT GCGCCCACC . .ACCCAACAT CAGTTCTCCA ratEGRl AGTAGCTTCG GCCCCGGGCT GCGCCCACC. .ACCCAACAT CAGCTCTCCA humanEGRl TGCAGCTCCA GCCCCGGGCT GCACCCCCCC GCCCCGACAC CAGCTCTCCA 801 850 mouseEGRl GCTCGCTGGT CCGGGATGGC AGCGGCCAAG GCCGAGATGC AATTGATGTC ratEGRl GCTCGCACGT CCGGGATGGC AGCGGCCAAG GCCGAGATGC AATTGATGTC humanEGRl GCCTGC TCGT CCAGGATGGC CGCGGCCAAG GCCGAGATGC AGCTGATGTC ED5 (rat) arms hybridise to bp 807-825 in rat sequ hED5 (hum) arms hybridise to bp 262-280 in hum sequ 851 900 mouseEGRl TCCGCTGCAG ATCTCTGACC CGTTCGGCTC CTTTCCTCAC TCACCCACCA ratEGRl TCCGCTGCAG ATCTCTGACC CGTTCGGCTC CTTTCCTCAC TCACCCACCA humanEGRl CCCGCTGCAG ATCTCTGACC CGTTCGGATC CTTTCCTCAC TCGCCCACCA 901 950 mouseEGRl TGGACAACTA CCCCAAACTG GAGGAGATGA TGCTGCTGAG CAACGGGGCT ratEGRl TGGACAACTA CCCCAAACTG GAGGAGATGA TGCTGCTGAG CAACGGGGCT humanEGRl TGGACAACTA CCCTAAGCTG GAGGAGATGA TGCTGCTGAG CAACGGGGCT ' 951 1000 mouseEGRl CCCCAGTTCC TCGGTGCTGC CGGAACCCCA GAGGGCAGCG GCGGTAAT .. ratEGRl CCCCAGTTCC TCGGTGCTGC CGGAACCCCA GAGGGCAGCG GCGGCAATAA humanEGRl CCCCAGTTCC TCGGCGCCGC CGGGGCCCCA GAGGGCAGCG GCAGCAACAG 1001 1050 mouseEGRl AGC AGCAGCAGCA CCAGCAGCGG GGGCGGTGGT GGGGGCGGCA ratEGRl CAGCAGCAGC AGCAGCAGCA GCAGCAGCGG GGGCGGTGGT GGGGGCGGCA humanEGRl CAGCAGCAGC AGCAGCGGGG GCGGTGGAGG CGGCGGGGGC GGCAGCAACA 1051 1100 mouseEGRl GCAACAGCGG CAGCAGCGCC TTCAATCCTC AAGGGGAGCC GAGCGAACAA ratEGRl GCAACAGCGG CAGCAGCGCT TTCAATCCTC AAGGGGAGCC GAGCGAACAA humanEGRl GCAGCAGCAG CAGCAGCACC TTCAACCCTC AGGCGGACAC GGGCGAGCAG 1101 1150 mouseEGRl CCCTATGAGC ACCTGACCAC AG...AGTCC TTTTCTGACA TCGCTCTGAA ratEGRl CCCTACGAGC ACCTGACCAC AGGTAAGCGG TGGTCTGCGC CGAGGCTGAA humanEGRl CCCTACGAGC ACCTGACCGC AG...AGTCT TTTCCTGACA TCTCTCTGAA 1151 1200 mouseEGRl TAATGAGAAG GCGATGGTGG AGACGAGTTA TCCCAGCCAA ACGACTCGGT ratEGRl TCCCCCTTCG TGACTACCCT AACGTCCAGT CCTTTGCAGC ACGGACCTGC humanEGRl CAACGAGAAG GTGCTGGTGG AGACCAGTTA CCCCAGCCAA ACCACTCGAC 1201 1250 mouseEGRl TGCCTCCCAT CACCTATACT GGCCGCTTCT CCCTGGAGCC CGCACCCAAC ratEGRl ATCTAGATCT TAGGGACGGG ATTGGGATTT CCCTCTATTC .. CACACAGC humanEGRl TGCCCCCCAT CACCTATACT GGCCGCTTTT CCCTGGAGCC TGCACCCAAC 1251 1300 mouseEGRl AGTGGCAACA CTTTGTGGCC TGAACCCCTT TTCAGCCTAG TCAGTGGCCT ratEGRl TCCAGGGACT TGTGTTAGAG GGATGTCTGG GGACCCCCCA ACCCTCCATC humanEGRl AGTGGCAACA CCTTGTGGCC CGAGCCCCTC TTCAGCTTGG TCAGTGGCCT 1301 1350 mouseEGRl CGTGAGCATG ACCAATCCTC CGACCTCTTC ATCCTCGGCG CCTTCTCCAG ratEGRl CTTGCGGGTG CGCGGAGGGC AGACCGTTTG TTTTGGATGG AGAACTCAAG humanEGRl AGTGAGCATG ACCAACCCAC CGGCCTCCTC GTCCTCAGCA CCATCTCCAG 1351 1400 mouseEGRl CTGCTTCATC GTCTTCCTCT GCCTCCCAGA GCCCGCCCCT GAGCTGTGCC ratEGRl TTGCGTGGGT GGCT GGAGT GGGGGAGGGT TTGTTTTGAT humanEGRl CGGCCTCCTC CGC ... CTCC GCCTCCCAGA GCCCACCCCT GAGCTGCGCA 1401 1450 mouseEGRl GTGCCGTCCA ACGACAGCAG TCCCATCTAC TCGGCTGCGC CCACCTTTCC ratEGRl GAGCAGGGTT GC....CCCC TCCCCCGCGC GCGTTGTCGC GAGCCTTGTT humanEGRl GTGCCATCCA ACGACAGCAG TCCCATTTAC TCAGCGGCAC CCACCTTCCC 1451 1500 mouseEGRl TACTCCCAAC ACTGACATTT TTCCTGAGCC CCAAAGCCAG GCCTTTCCTG ratEGRl TGCAGCTTGT TCCCAAGGAA GGGCTGAAAT CTGTCACCAG GGATGTCCCG humanEGRl CACGCCGAAC ACTGACATTT TCCCTGAGCC ACAAAGCCAG GCCTTCCCGG 1501 1550 mouseEGRl GCTCGGCAGG CACAGCCTTG CAGTACCCGC CTCCTGCCTA CCCTGCCACC ratEGRl CCGCCCAGGG TAGGGGCGCG CATTAGCTGT GGCC.ACTAG GGTGCTGGCG humanEGRl GCTCGGCAGG GACAGCGCTC CAGTACCCGC CTCCTGCCTA CCCTGCCGCC 1551 1600 mouseEGRl AAAGGTGGTT TCCAGGTTCC CATGATCCCT GACTATCTGT TTCCACAACA ratEGRl GGATTCCCTC ACCCCGGACG CCTGCTGCGG AGCGCTCTCA GAGCTGCAGT humanEGRl AAGGGTGGCT TCCAGGTTCC CATGATCCCC GACTACCTGT TTCCACAGCA 1601 1650 mouseEGRl ACAGGGAGAC CTGAGCCTGG GCACCCCAGA CCAGAAGCCC TTCCAGGGTC ratEGRl AGAGGGGGAT TCTCTGTTTG CGTCAGCTGT CGAAATGGCT CT GC humanEGRl GCAGGGGGAT CTGGGCCTGG GCACCCCAGA CCAGAAGCCC TTCCAGGGCC 1651 1700 mouseEGRl TGGAGAACCG TACCCAGCAG CCTTCGCTCA CTCCACTATC CACTATTAAA ratEGRl CACTGGAGCA GGTCCAGGAA CATTGCAATC TGCTGCTATC AATTATTAAC humanEGRl TGGAGAGCCG CACCCAGCAG CCTTCGCTAA CCCCTCTGTC TACTATTAAG 1701 1750 mouseEGRl GCCTTCGCCA CTCAGTCGGG CTCCCAGGAC TTAAAG GCTCTTA ratEGRl CACATCGAGA GTCAGTGGTA GCCGGGCGAC CTCTTGCCTG GCCGCTTCGG humanEGRl GCCTTTGCCA CTCAGTCGGG CTCCCAGGAC CTGAAG GCCCTCA 1751 1800 mouseEGRl ATACCACCTA CCAATCCCAG CTCATCA..A ACCCAGCCGC ATGCGCAAGT ratEGRl CTCTCATCGT CCAGTGATTG CTCTCCAGTA ACCAGGCCTC TCTGTTCTCT humanEGRl ATACCAGCTA CCAGTCCCAG CTCATCA..A ACCCAGCCGC ATGCGCAAGT 1801 1850 mouseEGRl ACCCCAACCG GCCCAGCAAG ACACCCCCCC ATGAACGCCC ATATGCTTGC ratEGRl TTCCTGCCAG AGTCCTTTTC TGACATCGCT CTGAATAACG AGAAG..GCG humanEGRl ATCCCAACCG GCCCAGCAAG ACGCCCCCCC ACGAACGCCC TTACGCTTGC 1851 1900 mouseEGRl CCTGTCGAGT CCTGCGATCG CCGCTTTTCT CGCTCGGATG AGCTTACCCG ratEGRl CTGGTGGAGA CAAGTTATCC CAGCCAAACT ACCCGGTTGC CTCCCATCAC humanEGRl CCAGTGGAGT CCTGTGATCG CCGCTTCTCC CGCTCCGACG AGCTCACCCG 1901 1950 mouseEGRl CCATATCCGC ATCCACACAG GCCAGAAGCC CTTCCAGTGT CGAATCTGCA ratEGRl CTATACTGGC CGCTTCTCCC TGGAGCCTGC ACCCAACAGT GGCAACACTT humanEGRl CCACATCCGC ATCCACACAG GCCAGAAGCC CTTCCAGTGC CGCATCTGCA 1951 2000 mouseEGRl TGCGTAACTT CAGTCGTAGT GACCACCTTA CCACCCACAT CCGCACCCAC ratEGRl TGTGGCCTGA ACCCCTTTTC AGCCTAGTCA GTGGCCTTGT GAGCATGACC humanEGRl TGCGCAACTT CAGCCGCAGC GACCACCTCA CCACCCACAT CCGCACCCAC 2001 2050 mouseEGRl ACAGGCGAGA AGCCTTTTGC CTGTGACATT TGTGGGAGGA AGTTTGCCAG ratEGRl AACCCTCCAA CCTCTTCATC CTCAGCGCCT TCTCCAGCTG CTTCATCGTC humanEGRl ACAGGCGAAA AGCCCTTCGC CTGCGACATC TGTGGAAGAA AGTTTGCCAG 2051 2100 mouseEGRl GAGTGATGAA CGCAAGAGGC ATACCAAAAT CCATTTAAGA CAGAAGGACA ratEGRl TTCCTCTGCC TCCCAGAGCC CACCCCTGAG CTGTGCCGTG CCGTCCAACG humanEGRl GAGCGATGAA CGCAAGAGGC ATACCAAGAT CCACTTGCGG CAGAAGGACA 2101 2150 mouseEGRl AGAAAGCAGA CAAAAGTGTG GTGGCCTCCC CGGCTGC... . CTCTTCACT ratEGRl ACAGCAGTCC CATTTACTCA GCTGCACCCA CCTTTCCTAC TCCCAACACT humanEGRl AGAAAGCAGA CAAAAGTGTT GTGGCCTCTT CGGCCACCTC CTCTCTCTCT 2151 2200 mouseEGRl CTCTTCTTAC CCATCCCCAG TGGCTACCTC ratEGRl GACATTTTTC CTGAGCCCCA AAGCCAGGCC humanEGRl TCCTACCCGT CCCCGGTTGC TACCTCTTAC CCGTCCCCGG TTACTACCTC 2201 2250 mouseEGRl CTACCCATCC CCTGCCACCA CCTCATTCCC ATCCCCTGTG CCCACTTCCT ratEGRl TTTCCTGGCT CTGCAGGCAC AGCCTTGCAG TACCCGCCTC CTGCCTACCC humanEGRl TTATCCATCC CCGGCCACCA CCTCATACCC ATCCCCTGTG CCCACCTCCT 2251 2300 mouseEGRl ACTCCTCTCC TGGCTCCTCC ACCTACCCAT CTCCTGCGCA CAGTGGCTTC ratEGRl TGCCACCAAG GGTGGTTTCC AGGTTCCCAT GATCCCTGAC TATCTGTTTC humanEGRl TCTCCTCTCC CGGCTCCTCG ACCTACCCAT CCCCTGTGCA CAGTGGCTTC 2301 2350 mouseEGRl CCGTCGCCGT CAGTGGCCAC CACCTTTGCC TCCGTTCC ratEGRl CACAACAACA GGGAGACCTG AGCCTGGGCA CCCCAGACCA GAAGCCCTTC humanEGRl CCCTCCCCGT CGGTGGCCAC CACGTACTCC TCTGTTCCC 2351 2400 mouseEGRl ....ACCTGC TTTCCCCACC CAGGTCAGCA GCTTCCCGTC TGCGGGCGTC ratEGRl CAGGGTCTGG AGAACCGTAC CCAGCAGCCT TCGCTCACTC CACTATCCAC humanEGRl CCTGC TTTCCCGGCC CAGGTCAGCA GCTTCCCTTC CTCAGCTGTC 2401 2450 mouseEGRl AGCAGCTCCT TCAGCACCTC AACTGGTCTT TCAGACATGA CAGCGACCTT ratEGRl TATCAAAGCC TTCGCCACTC AGTCGGGCTC CCAGGACTTA AAGGCTCTTA humanEGRl ACCAACTCCT TCAGCGCCTC CACAGGGCTT TCGGACATGA CAGCAACCTT 2451 2500 mouseEGRl TTCTCCCAGG ACAATTGAAA TTTGCTAAAG GGA ATAAAAG.. ratEGRl ATAACACCTA CCAGTCCCAA CTCATCAAAC CCAGCCGCAT GCGCAAGT .. humanEGRl TTCTCCCAGG ACAATTGAAA TTTGCTAAAG GGAAAGGGGA AAGAAAGGGA 2501 2550 mouseEGRl .AAAGCAAAG GGAGAGGCAG GAAAGACATA AAAGCA...C AGGAGGGAAG ratEGRl .ACCCCAACC GGCCCAGCAA GACACCCCCC CATGAACGCC CGTATGCTTG humanEGRl AAAGGGAGAA AAAGAAACAC AAGAGACTTA AAGGACAGGA GGAGGAGATG 2551 2600 mouseEGRl AGATGGCCGC AAGAGGGGCC ACCTCTTAGG TCAGATGGAA GATCTCAGAG ratEGRl CCCTGTTGAG TCCTGCGATC GCCGCTTTTC TCGCTCGGAT GAGCTTACAC humanEGRl GCCATAGGAG AGGAGGGTT . . CCTCTTAGG TCAGATGGAG GTTCTCAGAG 2601 2650 mouseEGRl CCAAGTCCTT CTACTCACGA GTA..GAAGG ACCGTTGGCC AACAGCCCTT ratEGRl GCCACATCCG CATCCATACA GGC.CAGAA GCCCTTCCAG TGTCGAATCT humanEGRl CCAAGTCCTC CCTCTCTACT GGAGTGGAAG GTCTATTGGC CAACAATCCT 2651 2700 mouseEGRl TCACTTACCA TCCCTGCCTC CCCCGTCCTG TTCCCTTTGA CTTCAGCTGC ratEGRl GCATGCGTAA TTTCAGTCGT AGTGACCACC TTACCACCCA CATCCGCACC humanEGRl TTCTGCCCAC TTCCCCTTCC CCAATTACTA TTCCCTTTGA CTTCAGCTGC 2701 2750 mouseEGRl CTGAAACAGC CATGTCCAAG TTCTTCACCT CTATCCAAAG GACTTGATTT ratEGRl C.ACACAGG CGAGAAGCCT TTTGCCTGTG ACATTTGTGG GAGAAAGTTT humanEGRl CTGAAACAGC CATGTCCAAG TTCTTCACCT CTATCCAAAG AACTTGATTT 2751 2800 mouseEGRl GCATGG TATTGGAT AAATCATTTC AGTATCCTCT ratEGRl GCCAGGAGTG ATGAACGCAA GAGGCATACC AAAATCCACT TAAGACAGAA humanEGRl GCATGGA TTTTGGAT AAATCATTTC AGTATCATCT 2801 2850 mouseEGRl CCATC ACATGCCTGG CCCTTGCTCC CTTCAGCGCT AGACCATCAA ratEGRl GGACAAGAAA GCAGACAAAA GTGTCGTGGC CTCCTCAGCT GCCTCTTCCC humanEGRl .... CCATCA TATGCCTGAC CCCTTGCTCC CTTCAATGCT AGAAAATCGA 2851 2900 mouseEGRl GTTGGCATAA AGAAAAAAAA ATGGGTTTGG GCCCTCAGAA CCCTGCCCTG ratEGRl TCTCTTCCTA CCCATCCCCA GTGGCTACCT CCTACCCATC CCCCGCCACC humanEGRl GTTGGC AAAAT GGGGTTTGGG CCCCTCAGAG CCCTGCCCTG 2901 2950 mouseEGRl CATCTTTGTA CAGCATCTGT GCCATGGATT TTGTTTTCCT TGGGGTATTC ratEGRl ACCTCATTTC CATCCCCAGT GCCCACCTCT TACTCCTCTC CGGGCTCCTC humanEGRl CACCCTTGTA CAGTGTCTGT GCCATGGATT TCGTTTTTCT TGGGGTACTC 2951 3000 mouseEGRl TTGATGTGAA GATAATTTGC ATACT CTATTGTAT TATTTGGAGT ratEGRl TACCTACCCG TCTCCTGCAC ACAGTGGCTT CCCATCGCCC TCGGTGGCCA humanEGRl TTGATGTGAA GATAATTTGC ATATT CTATTGTAT TATTTGGAGT 3001 3050 mouseEGRl TAAATCCTCA CTTTGGGG.. GAGGGGGGAG CAAAGCCAAG CAAACCAATG ratEGRl CCACCTATGC CTCCGTCC. CACCTGCTTT CCCTGCCCAG GTCAGCACCT humanEGRl TAGGTCCTCA CTTGGGGGAA AAAAAAAAAA AAAAGCCAAG CAAACCAATG 3051 3100 mouseEGRl ATGATCCTCT ATTTTGTGAT GACTCTGCTG TGACATTA ratEGRl TCCAGTCTGC AGGGGTCAGC AACTCCTTCA GCACCTCAAC GGGTCTTTCA humanEGRl GTGATCCTCT ATTTTGTGAT GATGCTGTGA CAATA 3101 3150 mouseEGRl . GGTTTGAAG CATTTTTTTT TTCAAGCAGC AGTCCTAGGT ATTAACTGGA ratEGRl GACATGACAG CAACCTTTTC TCCTAGGACA ATTGAAATTT GCTAAAGGGA humanEGRl ...AGTTTGA ACCTTTTTTT TTGAAACAGC AGTCCCAG.. .. TATTCTCA 3151 3200 mouseEGRl .. GCATGTGT CAGAGTGTTG TTCCGTTAAT TTTGTAAATA CTGGCTCGAC ratEGRl ATGAAAGAGA GCAAAGGGAG GGGAGCGCGA GAGACAATAA AGGACAGGAG humanEGRl GAGCATGTGT CAGAGTGTTG TTCCGTTAAC CTTTTTGTAA ATACTGCTTG 3201 3250 mouseEGRl . TGTAACTCT CACATGTGAC AAAGTATGGT TTGTTTGGTT GGGTTTTGTT ratEGRl . GGAAGAAAT GGCCCGCAAG AGGGGCTGCC TCTTAGGTCA GATGGAAGAT humanEGRl ACCGTACTCT CACATGTGGC AAAATATGGT TTGGTTTTTC TTTTTTTTTT 3251 3300 mouseEGRl TTTGAGAATT TTTTTGCCCG TCCCTTTGGT TTCAAAAGTT TCACGTCTTG ratEGRl CTCAGAGCCA AGTCCTTCTA GTCAGTAGAA GGCCCGTTGG CCACCAGCCC humanEGRl TTGAAAGTGT TTTTTCTTCG TCCTTTTGGT TTAAAAAGTT TCACGTCTTG 3301 3350 mouseEGRl GTGCCTTTTG TGTGACACGC CTT . CCGATG GCTTGACATG CGCA ratEGRl TTTCACTTAG CGTCCCTGCC CTC.CCCAGT CCCGGTCCTT TTGACTTCAG humanEGRl GTGCCTTTTG TGTGATGCCC CTTGCTGATG GCTTGACATG TGCAAT .... 3351 3400 mouseEGRl ... GATGTGA GGGACACGCT CACCTTAGCC TTAA...GGG GGTAGGAGTG ratEGRl CTGCCTGAAA CAGCCACGTC CAAGTTCTTC ACCT ... CTA TCCAAAGGAC humanEGRl TGTGA GGGACATGCT CACCTCTAGC CTTAAGGGGG GCAGGGAGTG 3401 3450 mouseEGRl ATGTGTTGGG GGAGGCTTGA GAGCAAAAAC GAGGAAGAGG GCTGAGCTGA ratEGRl TTGATTTGCA TGGTATTGGA TAAACCATTT CAGCATCATC TCCACCACAT humanEGRl ATGATTTGGG GGAGGCTTTG GGAGCAAAAT AAGGAAGAGG GCTGAGCTGA 3451 3500 mouseEGRl GCTTTCGGTC TCCAGAATGT AAGAAGAAAA AATTTAAACA AAAATCTGAA ratEGRl GCCTGGCCCT TGCTCCCTTC AGCACTAGAA CATCAAGTTG GCTGAAAAAA humanEGRl GCTTCGGTTC TCCAGAATGT AAGAAAACAA AATCTAAAAC AAAATCTGAA 3501 3550 mouseEGRl CTCTCAAAAG TCTATTTTTC TAAACTGAAA ATGTAAATTT ATACATCTAT ratEGRl AAAATGGGTC TGGGCCCTCA GAACCCTGCC CTGTATCTTT GTACA humanEGRl CTCTCAAAAG TCTATTTTTT TAA.CTGAAA ATGTAAATTT ATAAATATAT 3551 3600 mouseEGRl TCAGGAGTTG GAGTGTTGTG GTTACCTACT GAGTAGGCTG CAGTTTTTGT ratEGRl GCATCTGTGC CATGGATTTT GTTTTCCTTG GGGTATTCTT GATGTGAAGA humanEGRl TCAGGAGTTG GAATGTTGTA GTTACCTACT GAGTAGGCGG CGATTTTTGT 3601 ■ 3650 mouseEGRl ATGTTATGAA CATGAAGTTC ATTATTTTGT GGTTTTATTT TACTTTGTAC ratEGRl TAATTTGCAT ACTCTATTGT ACTATTTGGA GTTAAATTCT CACTTTGGGG humanEGRl ATGTTATGAA CATGCAGTTC ATTATTTTGT GGTTCTATTT TACTTTGTAC 3651 3700 mouseEGRl TTGTGTTTGC TTAAACAAAG TAACCTGTTT GGCTTATAAA CACATTGAAT ratEGRl GAGGGGGAGC AAAGCCAAGC AAACCAATGG TGATCCTCTA TTTTGTGATG humanEGRl TTGTGTTTGC TTAAACAAAG TGA.CTGTTT GGCTTATAAA CACATTGAAT 3701 3750 mouseEGRl GCGCTCTATT GCCCATGG.. .. GA ATGTG GTGTGTATCC TTCAGAAAAA ratEGRl ATCCTGCTGT GACATTAGGT TTGAAACTTT TTTTTTTTTT TGAAGCAGCA humanEGRl GCGCTTTATT GCCCATGG .. .. GATATGTG GTGTATATCC TTCCAAAAAA 3751 3800 mouseEGRl TTAAAAGGAA AAAT ratEGRl GTCCTAGGTA TTAACTGGAG CATGTGTCAG AGTGTTGTTC CGTTAATTTT humanEGRl TTAAAACGAA AATAAAGTAG CTGCGATTGG G 3801 3850 mouseEGRl ratEGRl GTAAATACTG CTCGACTGTA ACTCTCACAT GTGACAAAAT ACGGTTTGTT humanEGRl 3851 3900 mouseEGRl ratEGRl TGGTTGGGTT TTTTGTTGTT TTTGAAAAAA AAATTTTTTT TTTGCCCGTC humanEGRl 3901 3950 mouseEGRl ratEGRl CCTTTGGTTT CAAAAGTTTC ACGTCTTGGT GCCTTTGTGT GACACACCTT humanEGRl 3951 4000 mouseEGRl ratEGRl GCCGATGGCT GGACATGTGC AATCGTGAGG GGACACGCTC ACCTCTAGCC humanEGRl 4001 4050 mouseEGRl ratEGRl TTAAGGGGGT AGGAGTGATG TTTCAGGGGA GGCTTTAGAG CACGATGAGG humanEGRl 4051 4100 mouseEGRl ratEGRl AAGAGGGCTG AGCTGAGCTT TGGTTCTCCA GAATGTAAGA AGAAAAATTT humanEGRl 4101 4150 mouseEGRl ratEGRl AAAACAAAAA TCTGAACTCT CAAAAGTCTA TTTTTTTAAC TGAAAATGTA humanEGRl 4151 4200 mouseEGRl ratEGRl GATTTATCCA TGTTCGGGAG TTGGAATGCT GCGGTTACCT ACTGAGTAGG humanEGRl 4201 4250 mouseEGRl ratEGRl CGGTGACTTT TGTATGCTAT GAACATGAAG TTCATTATTT TGTGGTTTTA humanEGRl 4251 4300 mouseEGRl ratEGRl TTTTACTTCG TACTTGTGTT TGCTTAAACA AAGTGACTTG TTTGGCTTAT humanEGRl 4301 4350 mouseEGRl ratEGRl AAACACATTG AATGCGCTTT ACTGCCCATG GGATATGTGG TGTGTATCCT humanEGRl 4351 4388 mouseEGRl ratEGRl TCAGAAAAAT TAAAAGGAAA ATAAAGAAAC TAACTGGT humanEGRl EXPERIMENTAL DETAILS EXAMPLE 1 Role of EGR-1 in endothelial cell proliferation and migration Materials and Methods Oligonucleotides and chemicals. Phosphorothioate-linked antisense oligonucleotides directed against the region comprising the translational start site of Egr-1 mRNA were synthesized commercially (Genset Pacific) and purified by high performance liquid chromatography. The target sequence of AS2 (5'-CsTsTsGsGsCsCsGsCsTsGsCsCsAsT-3') (SEQ ID NO:16) is conserved in mouse, rat and human Egr-1 mRNA. For control purposes, we used AS2C (5'-GsCsAsCsTsTsCsTsGsCsTsGsTsCsC-3') (SEQ ID NO:17), a size-matched phosphorothioate-linked counterpart of AS2 with similar base composition. Phorbol-12-myristrate 13-acetate (PMA) and fibroblast growth factor-2 were purchased from Sigma-Aldrich. Cell culture. Bovine aortic endothelial cells were obtained from Cell Applications, Inc. and used between passages 5-9. The endothelial cells were grown in Dulbecco's modified Eagles' medium (Life Technologies), pH 7.4, containing 10% fetal bovine serum supplemented with 50 μg/mL streptomycin and 50 IU/mL penicillin. The cells were routinely passaged with trypsin/EDTA and maintained at 37°C in a humidified atmosphere of 5% Cθ2/95% air. Transient transfection analysis and.CAT ssay. The endothelial cells were grown to 60-70% confluence in 100mm dishes and transiently fransfected with 10 μg of the indicated chloramphenicol acetyl transferase (CAT)-based promoter reporter construct using FuGENE6 (Roche). The cells were rendered growth-quiescent by incubation 48 h in 0.25% FBS, and stimulated with various agonists for 24 h prior to harvest and assessment of CAT activity. CAT activity was measured and normalized to the concentration of protein in the lysates (determined by Biorad Protein Assay) as previously described (Khachigian et al., 1999). Noήhern blot analysis. Total RNA (12 g/well) of growth-arrested endothelial cells (prepared using TRIzol Reagent (Life Technologies) in accordance with the manufacturer's instructions) previously exposed to various agonists for 1 h was resolved by electrophoresis on denaturing 1% agarose-formaldehyde gels. Following transfer overnight to Hybond- N+ nylon membranes (Amersham), the blots were hybridized with 32 P-labeled Egr-1 cDNA prepared using the Nick Translation Kit overnight (Roche). The membranes were washed and radioactivity visualized by autoradiography as previously described (Khachigian et al., 1995). RT-PCR. Reverse transcription was performed with 8 μg of total RNA using M-MLV reverse transcriptase. Egr-1 cDNA was amplified (334 bp product (Delbridge et al., 1997)) using Taq polymerase by heating for 1 min at 94"C, and cycling through 94°C for 1 min, 94°C for 1 min, 55°C for 1 min, and 72°C for 1 min. Following thirty cycles, a 5 min extension at 72°C was carried out. Samples were electrophoresed on 1.5% agarose gel containing ethidium bromide and photographed under ultraviolet illumination, β-actin amplification (690 bp product) was performed essentially as above. The sequences of the primers were: Egr-1 forward primer (5 -GCA CCC AAC AGT GGC AAC-3') (SEQ ID NO: 18), Egr-1 reverse primer (5'-GGG ATC ATG GGA ACC TGG-3') (SEQ ID NO:19), β-actin forward primer (5'-TGA CGG GGT CAC CCA CAC TGT GCC CAT CTA 3') (SEQ ID NO: 20), and β-actin reverse primer (5'-CTA GAA GCA TTT GCG GTG GAC GAT GGA GGG-3') (SEQ ID NO: 21). Antisense oligonucleotide delivery and Western blot analysis. Growth- arrested cells in 100 mm dishes were incubated with the indicated oligonucleotides 24 h and 48 h after the initial change of medium. When oligonucleotide was added a second time, the cells were incubated with various concentrations of insulin and harvest 1 h subsequently. The cells were washed in cold phosphate-buffered saline (PBS), pH 7.4, and solubilized in RIPA buffer (150 mM NaCl, 50 mM Tris-HCl, pH 7.5, 1% sodium deoxycholate, 0.1% SDS, 1% Triton X-100, 5 mM EDTA, 1% trasylol, 10 μg/ml leupeptin, 1% aprotinin, 2 μM PMSF). Lysates were resolved by electrophoresis on 8% denaturing SDS-polyacrylamide gels, transferred to PDVF nylon membranes (NEN-DuPont), blocked with skim milk powder, then incubated with polyclonal antibodies to Egr-1 (Santa Cruz Biotechnology, Inc) and monoclonal horseradish peroxidase-linked mouse anti-rabbit Ig secondary antibodies followed by chemiluminescent detection (NEN-DuPont). 3 H-Thymidine incorporation into DNA. Growth-arrested endothelial cells at 90% confluence in 96 well plates were incubated twice with the oligonucleotides prior to the addition of insulin. When signaling inhibitors (PD98059, SB202190, wortmannin) were used in experiments, these agents were added 2 h before the addition of insulin. After 18 h of exposure to insulin, the cells were pulsed with 200,000 cpm/well of methyl- 3 H thymidine (NEN-DuPont) for 6 h. Lysates were prepared by washing first in cold PBS, pH7.4, then fixing with cold 10% trichloroacetic acid, washing with cold ethanol and solubilizing in 0.1 M NaOH. 3 H-Thymidine in the lysates was quantitated with ACSII scintillant using β-scintillation counter (Packard). In vitro injury. Growth-arrested cells at 90% confluence were incubated with antisense oligonucleotides and insulin at various concentrations as described above, then were scraped by drawing a sterile wooden toothpick across the monolayer (Khachigian et al., 1996). Following 48-72 h, the cells were fixed in 4% formalin, stained with hematoxylin/eosin then photographed. HMEC-1 culture and proliferation assay. SV40-transformed HMEC-1 cells were grown in MCDB 131 medium with EGF (10 ng/ml) and hydrocortisone (1 μg/ml) supplements and 10% FBS. Forty-eight h after incubation in serum-free medium without supplements, the cells were fransfected with the indicated DNA enzyme (0.4 μM) and fransfected again 72 h after the change of medium, when 10% serum was added. The cells were quantitated by Coulter counter, 24 h after the addition of serum. Antisense Egr-1 mRNA overexpression. Bovine aortic endothelial cells or rat vascular smooth muscle cells were grown to 60% confluence in 96-well plates then transfected with 3μg of construct pcDNA3-A/SEgr-l (in which a 137bp fragment of Egr-1 cDNA (732-869) was cloned in antisense orientation into the BamHI/EcoRI site of pcDNA3), or pcDNA3 alone, using Fugene6 in accordance with the manufacturer's instructions. Growth arrested cells were incubated with 5% FBS in Waymouth's medium (SMC) or DMEM (EC) and trypisinised after 3 days prior to quantitation of the cell populations by Coulter counting. Results and Discussion Insulin, but not Glucose, Stimulates Egr-1 Activity in Vascular Endothelial Cells. High glucose may activate normally-quiescent vascular endothelium by stimulating mitogen-activated protein (MAP) kinase activity and the expression of immediate-early genes (Frodin et al., 1995; Kang et al., 1999). These signaling and transcriptional events may, in turn, induce the expression of other genes whose products then alter endothelial phenotype and facilitate the development of lesions. To determine the effect of glucose on Egr-1 activity in vascular endothelial cells, we performed transient transfection analysis in endothelial cells transfected with pEBSl 3 foscat, a chloramphenical acetyltransferase (CAT)-based reporter vector driven by three high-affinity Egr-1 binding sites placed upstream of the c-fos TATA box (Gashler et al., 1993). Exposure of growth-arrested endothelial cells to various concentrations of glucose (5 to 30 mM) over 24 h did not increase Egr-1 binding activity (Figure 1). However, Egr-1 binding activity did increase in cells exposed to insulin (100 nM) (Figure 1). Reporter activity also increased upon incubation with FGF-2, a known inducer of Egr-1 transcription and binding activity in vascular endothelial cells (Santiago et al., 1999b) (Figure 1). Insulin and FGF-2 Induce Egr-1 mRNA Expression in Vascular Endothelial Cells. The preceding findings using reporter gene analysis provided evidence for increased Egr-1 expression in endothelial cells exposed to insulin. We next used reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis to demonstrate directly the capacity of insulin to increase levels of Egr-1 mRNA. RT-PCR revealed that Egr-1 is weakly expressed in growth-quiescent endothelial cells (data not shown). Insulin, like FGF-2, increased Egr-1 expression within 1 h of exposure to the agonist. In contrast, levels of β-actin mRNA were unchanged. Northern blot analysis confirmed these qualitative data by demonstrating that insulin, FGF- 2, and phorbol 12-myristate 13-acetate (PMA), a second potent inducer of Egr-1 expression (Khachigian et al., 1995) elevated steady-state Egr-1 mRNA levels within 1 h without increasing levels of ribosomal 28S and 18S mRNA (data not shown). Insulin-Stimulated Egr-1 Protein Synthesis in Endothelial Cells is Inhibited by Antisense Oligonucleotides Targeting Egr-1 mRNA. To reconcile our demonstration of insulin-induced Egr-1 mRNA expression with the binding activity of the transcription factor (Figure 1), we performed Western immunoblot analysis using polyclonal antibodies directed against Egr-1 protein. Insulin (at 100 nM and 500 nM) induced Egr-1 protein synthesis in growth-arrested endothelial cells within 1 h (data not shown). These findings, taken together, demonstrate that insulin elevates Egr-1 mRNA, protein and binding activity in vascular endothelial cells. We recently developed phosphorothioate-based antisense oligonucleotides targeting the translational start site in Egr-1 mRNA (Santiago et al., 1999c). These oligonucleotides lack phosphorothioate G- quartet sequences that have been associated with non-specific biological activity (Stein, 1997). Western blot analysis revealed that prior incubation of growth-arrested endothelial cells with 0.8 μM antisense Egr-1 oligonucleotides (AS2) inhibited insulin-inducible Egr-1 protein synthesis, despite equal loading of protein. The lack of attenuation in insulin-inducible Egr-1 protein following exposure of the cells to an identical concentration of AS2C demonstrates the sequence-specific inhibitory effect of the antisense Egr-1 oligonucleotides. Insulin Stimulates Endothelial Cell DNA Synthesis which is Inhibited by Antisense Oligonucleotides Targeting Egr-1 mRNA. These oligonucleotides, which attenuate the induction of Egr-1 protein, were used in 3 H-thymidine incorporation assays to determine the involvement of Egr-1 in insulin- inducible DNA synthesis. This assay evaluates 3 H- thymidine uptake into DNA precipitable with trichloroacetic acetic (TCA) (Khachigian et al., 1992). In initial experiments, growth-arrested endothelial cells exposed to insulin (100 nM) increased the extent of DNA synthesis by 100%, whereas 500 nM insulin caused a 200% increase in DNA synthesis (Figure 2A). We next determined the effect of AS2 and AS2C on insulin-inducible endothelial DNA synthesis. In the absence of added insulin, AS2 (0.8 μM) inhibited basal endothelial DNA synthesis facilitated by low concentrations of serum (0.25% v:v) (Figure 2B). In contrast, the scrambled control (0.8 μM) or a third oligonucleotide, E3 (0.8 μM), a size-matched phosphorothioate directed toward another region of Egr-1 mRNA (Santiago et al., 1999c) had little effect on basal DNA synthesis (Figure 2B). Furthermore, unlike AS2 and E3, AS2 significantly inhibited DNA synthesis inducible by insulin (500 nM and 1000 nM) (Figure 2B). To demonstrate concentration-dependent inhibition of DNA synthesis, we incubated the endothelial cells with 0.4 μM as well as 0.8 μM of Egr-1 oligonucleotide. Since this lower concentration of AS2 inhibited 3H-thymidine incorporation less effectively (compare to AS2C) indicates dose-dependent and sequence-specific inhibition by the antisense Egr-1 oligonucleotide (Figure 2C). These findings thus demonstrate the requirement for Egr-1 protein in endothelial cell DNA synthesis inducible by insulin. Insulin-Stimulated DNA Synthesis in Endothelial Cells is Inhibited by PD98059 and Wortmannin, But Not by SB202190. Inducible Egr-1 transcription is governed by the activity of extracellular signal-regulated kinase (ERK) (Santiago et al., 1999b) which phosphorylates factors at serum response elements in the Egr-1 promoter (Gashler et al, 1995). Since there is little known about signaling pathways mediating insulin-inducible proliferation of vascular endothelial cells, we determined the relevance of MEK/ERK in this process using the specific MEK/ERK inhibitor, PD98059. This compound (at 10 and 30 μM) inhibited insulin-inducible DNA synthesis in a dose-dependent manner (Figure 3). Likewise, wortmannin (0.3 and 1 μM), the phosphatidylinositol 3-kinase inhibitor which also inhibits c-Jun N- terminal kinase (JNK) (Ishizuka et al, 1999; Day et al., 1999; Kumahara et al., 1999), ERK (Barry et al., 1999) and p38 kinase (Barry et al„ 1999) inhibited DNA synthesis in a dose-dependent manner (Figure 3). In contrast, SB202190 (100 and 500 nM), a specific p38 kinase inhibitor failed to affect DNA synthesis (Figure 3). These findings demonstrate the critical role for MEK/ERK, and possibly JNK, in insulin-inducible endothelial cell proliferation, and the lack of p38 kinase involvement in this process. Insulin Stimulates Endothelial Cell Regrowth After Mechanical Injury In Vitro in an Egr-1 -Dependent Manner. Mechanically wounding vascular endothelial (and smooth muscle) cells in culture results in migration and proliferation at the wound edge and the eventual recoverage of the denuded area. We hypothesized that insulin would accelerate this cellular response to mechanical injury. Acutely scraping the growth-quiescent (rendered by 48 h incubation in 0.25% serum) endothelial monolayer resulted in a distinct wound edge (data not shown). Continued incubation of the cultures in medium containing low serum for a further 3 days resulted in weak regrowth in the denuded zone but aggressive regrowth in the presence of optimal amounts of serum (10%). When insulin (500 nM) was added to growth- quiescent cultures at the time of injury the population of cells in the denuded zone significantly increased, albeit as expected, less efficiently than the 10% serum control. To investigate the involvement of Egr-1 in endothelial regrowth potentiated by insulin after injury we incubated the cultures with antisense Egr-1 oligonucleotides prior to scraping and again at the time of injury and the addition of insulin. AS2 (0.8 μM) significantly inhibited endothelial regrowth stimulated by insulin. In contrast, regrowth in the presence of AS2C (0.8 μM) was not significantly different from cultures in which oligonucleotide was omitted. Similar findings were observed when higher concentrations (1.2 μM) of AS2 and AS2C were used. Thus, endothelial regrowth after injury stimulated by insulin proceeds in an Egr-1-dependent manner. These observations are quantitated in Figure 4. These results show that insulin-induced proliferation and regrowth after injury are processes critically dependent upon the activation of Egr-1. Northern blot, RT-PCR and Western immunoblot analysis reveal that insulin induces Egr-1 mRNA and protein expression. Antisense oligonucleotides which block insulin-induced synthesis of Egr-1 protein in a sequence-specific and dose-dependent manner, also inhibit proliferation and regrowth after mechanical injury. These findings using nucleic acids specifically targeting Egr-1 demonstrate the functional involvement of this transcription factor in endothelial growth. Insulin signaling involves the activation of a growing number of immediate-early genes and transcription factors. These include c-fos (Mohn et al, 1990; Jhun et al, 1995; Harada et al., 1996), c-jun (Mohn et al., 1990), nuclear factor-κB (Bertrand et al., 1998), SOCS3 (Emanuelli et al., 2000) and the forkhead transcription factor FKHR (Nakae et al., 1999). Insulin also induces the expression of Egr-1 in mesangial cells (Solow et al., 1999), fibroblasts (Jhun et al., 1995), adipocytes (Alexander-Bridges et al., 1992) and Chinese hamster ovary cells (Harada et al., 1996). This study is the first to describe the induction of Egr-1 by insulin in vascular endothelial cells. Insulin activates several subclasses within the MAP kinase superfamily, including ERK, JNK and p38 kinase (Guo et al, 1998). Our findings indicate that the specific ERK inhibitor PD98059, which binds to MEK and prevents phosphorylation by Raf, inhibits insulin-inducible endothelial cell proliferation. Egr-1 transcription is itself dependent upon the phosphorylation activity of ERK via its activation of ternary complex factors (such as Elk-1) at serum response elements (SRE) in the Egr-1 promoter. Six SREs appear in the Egr-1 promoter whereas only one is present in the c-fos promoter (Gashler et al., 1995). PD98059 blocks insulin- inducible Elk-1 transcriptional activity at the c-fos SRE in vascular cells (Xi et al., 1997). These published findings are consistent with the present demonstration of the involvement of Egr-1 in insulin-inducible proliferation. To provide evidence, independent of insulin, that endothelial proliferation is an Egr-1-dependent process, we incubated human microvascular endothelial cells (HMEC-1) separately with two DNA enzymes (DzA and DzF) each targeting different sites in human EGR-1 mRNA, at a final concentration of 0.4 μM. DzA and DzF both inhibited HMEC-1 replication (total cell counts) in the presence of 5% serum (Figure 5). In contrast, DzFscr, was unable to modulate proliferation at the same concentration (Figure 5). DzFscr bears the same active 15nt catalytic domain as DzF and has the same net charge but has scrambled hybridizing arms. These data obtained using a second endothelial cell type demonstrate inhibition of endothelial proliferation using sequence-specific strategies targeting human EGR-1. Finally, we found that CMV-mediated overexpression of antisense Egr- 1 mRNA inhibited proliferation of both endothelial cells and smooth muscle cells. Replication of both endothelial and smooth muscle cell pcDNA3- A/SEgr-1 transfectants was significantly lower than those transfected with the backbone vector alone, pcDNA3 (data not shown). These findings demonstrate that antisense EGR mRNA strategies can inhibit proliferation of arterial endothelial cells and at least one other vascular cell type. Despite the availability and clinical use of a large number of chemotherapeutic agents for the clinical management of neoplasia, solid tumours remain a major cause of mortality in the Western world. Drugs currently used to treat such tumours are generally non-specific poisons that can be toxic to non-cancerous tissue and require high doses for efficacy. There is growing evidence that the cellular and molecular mechanisms underlying tumour growth involves more than just tumour cell proliferation and migration. Importantly, tumour growth and metastasis are critically dependent upon ongoing angiogenesis, the process new blood vessel formation (Crystal et al., 1999). The present findings, which demonstrate that Egr-1 is critical in vascular endothelial cell replication and migration, strongly implicate this transcription factor as a key regulator in angiogenesis and tumorigenesis. Example 2 Characterisation of DNAzyme targeting rat Egr-1 (NGFI-A) Materials and Methods ODN synthesis. DNAzymes were synthesized commercially (Oligos Etc., Inc.) with an inverted T at the 3' position unless otherwise indicated. Substrates in cleavage reactions were synthesized with no such modification. Where indicated ODNs were 5 '-end labeled with γ 32 P-dATP and T4 polynucleotide kinase (New England Biolabs). Unincorporated label was separated from radiolabeled species by centrifugation on Chromaspin-10 columns (Clontech). In vitro transcript and cleavage experiments. A 32 P-labelled 206 nt NGFI-A RNA transcript was prepared by in vitro transcription (T3 polymerase) of plasmid construct pJDM8 (as described in Milbrandt, 1987, the entire contents of which are incorporated herein by reference) previously cut with Bgl II. Reactions were performed in a total volume of 20 μl containing 10 mM MgCl 2 , 5 mM Tris pH 7.5, 150 mM NaCl, 4.8 pmol of in vitro transcribed or synthetic RNA substrate and 60 pmol DNAzyme (1:12.5 substrate to DNAzyme ratio), unless otherwise indicated. Reactions were allowed to proceed at 37 °C for the times indicated and quenched by transferring an aliquot to tubes containing formamide loading buffer (Sambrook et al, 1989). Samples were run on 12% denaturing polyacrylamide gels and autoradiographed overnight at -80 °C. Culture conditions and DNAzyme transfection. Primary rat aortic SMCs were obtained from Cell Applications, Inc., and grown in Waymouth's medium, pH 7.4, containing 10% fetal bovine serum (FBS), 50 μg ml streptomycin and 50 IU/ml penicillin at 37 °C in a humidified atmosphere of 5% CO 2 . SMCs were used in experiments between passages 3-7. Pup rat SMCs (WKY12-22 (as described in Lemire et al, 1994, the entire contents of which are incorporated herein by reference)) were grown under similar conditions. Subconfluent (60-70%) SMCs were incubated in serum-free medium (SFM) for 6 h prior to DNAzyme (or antisense ODN, where indicated) transfection (0.1 μM) using Superfect in accordance with manufacturer's instructions (Qiagen). After 18 h, the cells were washed with phosphate-buffered saline (PBS), pH 7.4 prior to transfection a second time in 5% FBS. Northern blot analysis. Total RNA was isolated using the TRIzol reagent (Life Technologies) and 25 μg was resolved by electrophoresis prior to transfer to Hybond-N+ membranes (NEN-DuPont). Prehybridization, hybridization with α 32 P-dCTP-labeled Egr-1 or β-Actin cDNA, and washing was performed essentially as previously described (Khachigian et al, 1995). Western blot analysis. Growth-quiescent SMCs in 100 mm plates (Nunc-InterMed) were transfected with ED5 or ED5SCR as above, and incubated with 5% FBS for 1 h. The cells were washed in cold PBS, pH 7.4, and extracted in 150 mM NaCl, 50 mM Tris-HCl, pH 7.5, 1% sodium deoxycholate, 0.1% SDS, 1% Triton X-100, 5 mM EDTA, 1% trasylol, 10 μg/ml leupeptin, 1% aprotinin and 2 mM PMSF. Twenty four μg protein samples were loaded onto 10% denaturing SDS-polyacrylamide gels and electroblotted onto PVDF nylon membranes (NEN-DuPont) . Membranes were air dried prior to blocking with non-fat skim milk powder in PBS containing 0.05% (w:v) Tween 20. Membranes were incubated with rabbit antibodies to Egr-1 or Spl (Santa Cruz Biotechnology, Inc.) (1:1000) then with HRP-linked mouse anti-rabbit Ig secondary antiserum (1:2000). Where mouse monoclonal c-Fos (Santa Cruz Biotechnology, Inc.) was used, detection was achieved with HRP-linked rabbit anti-mouse Ig. Proteins were visualized by chemiluminescent detection (NEN-DuPont) . Assays of cell proliferation. Growth-quiescent SMCs in 96-well titer plates (Nunc-InterMed) were transfected with ED5 or ED5SCR as above, then exposed to 5% FBS at 37 °C for 72 h. The cells were rinsed with PBS, pH 7.4, trypsinized and the suspension was quantitated using an automated Coulter counter. Assessment of DNAzyme stability. DNAzymes were 5'-end labeled with γ 32 P-dATP and separated from free label by centrifugation. Radiolabeled DNAzymes were incubated in 5% FBS or serum-free medium at 37 °C for the times indicated. Aliquots of the reaction were quenched by transfer to tubes containing formamide loading buffer (Sambrook et al, 1989). Samples were applied to 12% denaturing polyacrylamide gels and autoradiographed overnight at -80 °C. SMC wounding assay. Confluent growth-quiescent SMCs in chamber slides (Nunc-InterMed) were exposed to ED5 or ED5SCR for 18 h prior to a single scrape with a sterile toothpick. Cells were treated with mitomycin C (Sigma) (20 μM) for 2 h prior to injury (Pitsch et al, 1996; Horodyski & Powell, 1996). Seventy-two h after injury, the cells were washed with PBS, pH 7.4, fixed with formaldehyde then stained with hematoxylin-eosin. Rat arterial ligation model and analysis. Adult male Sprague Dawley rats weighing 300-350 g were anaesthetised using ketamine (60 mg/kg, i.p.) and xylazine (8 mg/kg, i.p.). The right common carotid artery was exposed up to the carotid bifurcation via a midline neck incision. Size 6/0 non- absorbable suture was tied around the common carotid proximal to the bifurcation, ensuring cessation of blood flow distally. A 200 μl solution at 4°C containing 500 μg of DNAzyme (in DEPC-treated H 2 0), ImM MgCl 2 , 30 μl of transfecting agent (Fugene 6) and Pluronic gel P127 (BASF) was applied around the vessel in each group of 5 rats, extending proximally from the ligature for 12-15 mm. These agents did not inhibit the solidification of the gel at 37 °C. After 3 days, vehicle with or without 500 μg of DNAzyme was administered a second time. Animals were sacrificed 18 days after ligation by lethal injection of phenobarbitone, and perfusion fixed using 10% (v:v) formaldehyde perfused at 120 mm Hg. Both carotids were then dissected free and placed in 10% formaldehyde, cut in 2 mm lengths and embedded in 3% (w:v) agarose prior to fixation in paraffin. Five μm sections were prepared at 250 μm intervals along the vessel from the point of ligation and stained with hematoxylin and eosin. The neointimal and medial areas of 5 consecutive sections per rat were determined digitally using a customized software package (Magellan) (Halasz & Martin, 1984) and expressed as a mean ratio per group of 5 rats. Results and Discussion The 7x7 nt arms flanking the 15 nt DNAzyme catalytic domain in the original DNAzyme design (Santoro and Joyce, 1997) were extended by 2 nts per arm for improved specificity (L.-Q. Sun, data not shown) (Figure 6). The 3' terminus of the molecule was capped with an inverted 3'-3'-linked thymidine (T) to confer resistance to 3'->5' exonuclease digestion. The sequence in both arms of ED5 was scrambled (SCR) without altering the catalytic domain to produce DNAzyme ED5SCR (Figure 6). A synthetic RNA substrate comprised of 23 nts, matching nts 805 to 827 of NGFI-A mRNA (Figure 6) was used to determine whether ED5 had the capacity to cleave target RNA. ED5 cleaved the 32 P-5'-end labeled 23-mer within 10 min (data not shown). The 12-mer product corresponds to the length between the A(816)-U(817) junction and the 5' end of the substrate (Figure 6). In contrast, ED5SCR had no demonstrable effect on this synthetic substrate. Specific ED5 catalysis was further demonstrated by the inability of the human equivalent of this DNAzyme (hED5) to cleave the rat substrate over a wide range of stoichiometric ratios (data not shown). Similar results were obtained using ED5SCR (data not shown). hED5 differs from the rat ED5 sequence by 3 of 18 nts in its hybridizing arms (Table 2). The catalytic effect of ED5 on a 32 P-labeled 206 nt fragment of native NGFI-A mRNA prepared by in vitro transcription was then determined. The cleavage reaction produced two radiolabeled species of 163 and 43 nt length consistent with DNAzyme cleavage at the A(816)-U(817) junction. In other experiments, ED5 also cleaved a 32 P-labeled NGFI-A transcript of 1960 nt length in a specific and time-dependent manner (data not shown). Table 2. DNAzyme target sites in mRNA. Similarity between the 18 nt arms of ED5 or hED5 and the mRNA of rat NGFI-A or human EGR-1 (among other transcription factors) is expressed as a percentage. The target sequence of ED5 in NGFI-A mRNA is 5'-807-A CGU CCG GGA UGG CAG CGG-825-3' (SEQ ID NO: 22) (rat NGFI-A sequence), and that of hED5 in EGR-1 is 5'-262-U CGU CCA GGA UGG CCG CGG-280-3' (SEQ ID NO: 23) (Human EGR-1 sequence). Nucleotides in bold indicate mismatches between rat and human sequences. Data obtained by a gap best fit search in ANGIS using sequences derived from Genbank and EMBL. Rat sequences for Spl and c-Fos have not been reported. Gene Accession Best homology over 18 nts number (%) ED5 hED5 Rat NGFI-A M18416 100 84.2 Human EGR-1 X52541 84.2 100 Murine Spl AF022363 66.7 66.7 Human c-Fos K00650 66.7 66.7 Murine c-Fos X06769 61.1 66.7 Human Spl AF044026 38.9 28.9 To determine the effect of the DNAzymes on endogenous levels of NGFI-A mRNA, growth-quiescent SMCs were exposed to ED5 prior to stimulation with serum. Northern blot and densitometric analysis revealed that ED5 (0.1 μM) inhibited serum-inducible steady-state NGFI-A mRNA levels by 55% (data not shown), whereas ED5SCR had no effect (data not shown). The capacity of ED5 to inhibit NGFI-A synthesis at the level of protein was assessed by Western blot analysis. Serum-induction of NGFI-A protein was suppressed by ED5. In contrast, neither ED5SCR nor EDC, a DNAzyme bearing an identical catalytic domain as ED5 and ED5SCR but flanked by nonsense arms had any influence on the induction of NGFI-A (Figure 7). ED5 failed to affect levels of the constitutively expressed, structurally- related zinc-finger protein, Spl (Figure 7). It was also unable to block serum-induction of the immediate-early gene product, c-Fos (Figure 7) whose induction, like NGFI-A, is dependent upon serum response elements in its promoter and phosphorylation mediated by extracellular-signal regulated kinase (Treisman, 1990, 1994 and 1995; Gashler & Sukhatme, 1995). These findings, taken together, demonstrate the capacity of ED5 to inhibit production of NGFI-A mRNA and protein in a gene-specific and sequence-specific manner, consistent with the lack of significant homology between its target site in NGFI-A mRNA and other mRNA (Table 2). The effect of ED5 on SMC replication was next determined. Growth- quiescent SMCs were incubated with DNAzyme prior to exposure to serum and the assessment of cell numbers after 3 days. ED5 (0.1 μM) inhibited SMC proliferation stimulated by serum by 70% (Figure 8a). In contrast, ED5SCR failed to influence SMC growth (Figure 8a). AS2, an antisense NGFI-A ODN able to inhibit SMC growth at 1 μM failed to inhibit proliferation at the lower concentration (Figure 8a). Additional experiments revealed that ED5 also blocked serum-inducible 3 H-thymidine incorporation into DNA (data not shown). ED5 inhibition was not a consequence of cell death since no change in morphology was observed, and the proportion of cells incorporating Trypan Blue in the presence of serum was not influenced by either DNAzyme (Figure 8b). Cultured SMCs derived from the aortae of 2 week-old rats (WKY12-22) are morphologically and phenotypically similar to SMCs derived from the neointima of balloon-injured rat arteries (Seifert et al, 1984; Majesky et al, 1992). The epitheloid appearance of both WKY12-22 cells and neointimal cells contrasts with the elongated, bipolar nature of SMCs derived from normal quiescent media (Majesky et al, 1988). WKY12-22 cells grow more rapidly than medial SMCs and overexpress a large number of growth- regulatory molecules (Lemire et al, 1994), such as NGFI-A (Rafty & Khachigian, 1998), consistent with a "synthetic" phenotype (Majesky et al, 1992; Campbell & Campbell, 1985). ED5 attenuated serum-inducible WKY12- 22 proliferation by approximately 75% (Figure 8c). ED5SCR had no inhibitory effect; surprisingly, it appeared to stimulate growth (Figure 8c). Trypan Blue exclusion revealed that DNAzyme inhibition was not a consequence of cytotoxicity (data not shown). To ensure that differences in the biological effects of ED5 and ED5SCR were not the consequence of dissimilar intracellular localization, both DNAzymes were 5 '-end labeled with fluorescein isothiocyanate (FITC) and incubated with SMCs. Fluorescence microscopy revealed that both FITC- ED5 and FITC-ED5SCR localized mainly within the nuclei. Punctate fluorescence in this cellular compartment was independent of DNAzyme sequence. Fluorescence was also observed in the cytoplasm, albeit with less intensity. Cultures not exposed to DNAzyme showed no evidence of autofluorescence. Both molecules were 5 '-end labeled with γ 3Z P-dATP and incubated in culture medium to ascertain whether cellular responsiveness to ED5 and ED5SCR was a consequence of differences in DNAzyme stability. Both 32 P- ED5 and 3Z P-ED5SCR remained intact even after 48 h (data not shown). In contrast to 2 P-ED5 bearing the 3' inverted T, degradation of 32 P-ED5 bearing its 3' T in the correct orientation was observed as early as 1 h. Exposure to serum-free medium did not result in degradation of the molecule even after 48 h (data not shown). These findings indicate that inverse orientation of the 3' base in the DNAzyme protects the molecule from nucleolytic cleavage by components in serum. Physical trauma imparted to SMCs in culture results in outward migration from the wound edge and proliferation in the denuded zone. We determined whether ED5 could modulate this response to injury by exposing growth-quiescent SMCs to either DNazyme and Mitomycin C, an inhibitor of proliferation (Pitsch et al, 1996; Horodyski & Powell, 1996) prior to scraping. Cultures in which DNAzyme was absent repopulated the entire denuded zone within 3 days. ED5 inhibited this reparative response to injury and prevented additional growth in this area even after 6 days (data not shown). That ED5SCR had no effect in this system further demonstrates sequence- specific inhibition by ED5. The effect of ED5 on neointima formation was investigated in a rat model. Complete ligation of the right common carotid artery proximal to the bifurcation results in migration of SMCs from the media to the intima where proliferation eventually leads to the formation of a neointima (Kumar & Lindner, 1997; Bhawan et al, 1977; Buck, 1961). Intimal thickening 18 days after ligation was inhibited 50% by ED5 (Figure 9). In contrast, neither its scrambled counterpart (Figure 9) nor the vehicle control (Figure 9) had any effect on neointima formation. These findings demonstrate the capacity of ED5 to suppress SMC accumulation in the vascular lumen in a specific manner, and argue against inhibition as a mere consequence of a "mass effect" (Kitze et al, 1998; Tharlow et al, 1996). Sequence specific inhibition of inducible NGFI-A protein expression and intimal thickening by ED5 was also observed in the rat carotid balloon injury model (Santiago et al., 1999a). Further experiments revealed the capacity of hED5 to cleave (human) EGR-1 RNA. hED5 cleaved its substrate in a dose-dependent manner over a wide range of stoichiometric ratios. hED5 also cleaved in a time-dependent manner, whereas hEDδSCR, its scrambled counterpart, had no such catalytic property (data not shown). The specific, growth-inhibitory properties of antisense EGR-1 strategies reported herein suggest that EGR-1 inhibitors may be useful as therapeutic tools in the treatment of vascular disorders involving inappropriate SMC growth, endothelial growth and tumour growth. EXAMPLE 3 Use of DNAzymes to inhibit growth of malignant cells Materials and Methods HepG2 cells were routinely grown in DMEM, pH 7.4, containing 10 % fetal calf serum supplemented with antibiotics. The cells were trypsinized, resuspended in growth medium (to 10,000 cells/200 μl) and 200 μl transferred into sterile 96 well titre plates. Two days subsequently, 180 μl of the culture supernatant was removed, the cells were washed with PBS, pH 7.4, and refed with 180 μl of serum free media. After 6 h, the first transfection of DNAzyme (2 μg/200μl wall, 0.75 μM final) was performed in tubes containing serum free media using FuGENE6 at a ratio of 1:3 (μg:μl). After 15 min incubation at room temperature, 180 μl of the culture supernantant was replaced with 180 μl of the transfection mix. After 24 h, 180μl of the supernatant was replaced with 180 μl of new transfection mix, but this time in 5% FBS media. After 3 days, the cells were washed in PBS, pH 7.4, and resuspended by trypsinization in 100 μl trypsin-EDTA. The cells were shaken for approximately 5 min to ensure the cells were in suspension. The entire suspension was placed into 10 ml of Isoton II. That all the cells were transferred was ensured by pipetting Isoton II solution from tubes back into wells several times. Using Isoton II only, background cell number was determined. Each sample was counted three times and used to calculate mean counts and standard errors of each mean. Results and Discussion Our results indicate that serum stimulated HepG2 cell proliferation after 3 days (Figure 10). Proliferation was almost completely suppressed by 0.75 μM of DzA (5'-caggggacaGGCTAGCTACAACGAcgttgcggg (SEQ ID NO:3), catalytic moiety in capitals), a DNAzyme targeting human EGR-1 mRNA (arms hybridize to nts 189-207) (Figure 10). In contrast, HepG2 cell growth was not inhibited by ED5SCR (Figure 10). Western blot analysis revealed that DzA strongly inhibited EGR-1 expression in HepG2 cells, whereas a size matched DNAzyme with different sequence (5'-tcagctgcaGGCTAGCTACAACGActcggcctt) (SEQ ID NO:24) had no effect (data not shown). These data indicate that inducible proliferation of this model human malignant cell line can be blocked by the EGR-1 DNAzyme. These findings suggest that EGR inhibitors may be clinically useful in therapeutic strategies targeting human cancer. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. Throughout this application, various publications are cited. 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Claims: Claims: 1. A method for the treatment of a tumour, the method comprising administering to a subject in need thereof an agent which inhibits induction of an EGR, an agent which decreases expression of an EGR or an agent which decreases the nuclear accumulation or activity of an EGR. 2. A method as claimed in claim 1 in which the agent inhibits angiogenesis. 3. A method as claimed in claim 1 or claim 2 in which the agent directly inhibits proliferation of the tumour cells. 4. A method as claimed in any one of claims 1 to 3 in which the tumour is a solid tumour. 5. A method as claimed in any one of claims 1 to 4 in which the EGR is EGR-1. 6. A method as claimed in any one of claims 1 to 5 in which the expression of EGR is decreased. 7. A method as claimed in claim 6 in which the expression of EGR is decreased by the use of an EGR antisense oligonucleotide. 8. A method as claimed in claim 7 in which the antisense oligonucleotide has a sequence selected from the group consisting of (i) ACA CTT TTG TCT GCT (SEQ ID NO:4), and (ii) CTT GGC CGC TGC CAT (SEQ ID NO:2). 9. A method as claimed in claim 6 in which the expression of EGR is decreased by the cleavage of EGR mRNA by a sequence-specific ribozyme. 10. A method as claimed in claim 6 in which the expression of EGR is decreased by the use of a ssDNA targeted against EGR dsDNA the ssDNA molecule being selected so as to form a triple helix with the dsDNA. 11. A method as claimed claim 6 in which the expression of EGR is decreased by inhibiting transcription of the EGR gene using a nucleic acid transcriptional decoy. 12. A method as claimed in claim 6 in which the expression of EGR is decreased by the expression of antisense EGR mRNA . 13. A method as claimed in claim 6 in which the expression of EGR is decreased by cleavage of EGR mRNA by a sequence specific DNAzyme. 14. A method as claimed in claim 13 in which the DNAzyme comprises (i) a catalytic domain which cleaves mRNA at a purine:pyrimidine cleavage site; (ii) a first binding domain contiguous with the 5' end of the catalytic domain; and (iii) a second binding domain contiguous with the 3' end of the catalytic domain, wherein the binding domains are sufficiently complementary to two regions immediately flanking a purine:pyrimidine cleavage site within the region of EGR mRNA corresponding to nucleotides 168 to 332 as shown in SEQ ID NO:15, such that the DNAzyme cleaves the EGR mRNA. 15. A method as claimed in claim 13 or claim 14 in which the catalytic domain has the nucleotide sequence GGCTAGCTACAACGA. 16. A method as claimed in any one of claims 13 to 15 in which the cleavage site is selected from the group consisting of (i) the GU site corresponding to nucleotides 198-199; (ii) the GU site corresponding to nucleotides 200-201; (iii) the GU site corresponding to nucleotides 264-265; (iv) the AU site corresponding to nucleotides 271-272; (v) the AU site corresponding to nucleotides 301-302; (vi) the GU site corresponding to nucleotides 303-304; and (vii) the AU site corresponding to nucleotides 316-317. 17. A method as claimed in claim 16 in which the cleavage site is the GU site corresponding to nucleotides 198-199, the AU site corresponding to nucleotides 271-272 or the AU site corresponding to nucleotides 301-302. 18. A method as claimed in claim 16 in which the DNAzyme has a sequence selected from the group consisting of: (i) 5'-caggggacaGGCTAGCTACAACGAcgttgcggg (SEQ ID NO:3); (ii) 5'-tgcaggggaGGCTAGCTACAACGAaccgttgcg (SEQ ID NO:6); (iii) 5'-catcctggaGGCTAGCTACAACGAgagcaggct (SEQ ID NO: 7); (iv) 5'-ccgcggccaGGCTAGCTACAACGAcctggacga (SEQ ID NO:8); (v) 5'-ccgctgccaGGCTAGCTACAACGAcccggacgt (SEQ ID NO:9) ; (vi) 5'-gcggggacaGGCTAGCTACAACGAcagctgcat (SEQ ID NO:10); (vii) 5'-cagcggggaGGCTAGCTACAACGAatcagctgc (SEQ ID NO: 11); and (viii) 5'-ggtcagagaGGCTAGCTACAACGActgcagcgg (SEQ ID NO:12). 19. A method as claimed in claim 18 in which the DNAzyme has the sequence: 5'-caggggacaGGCTAGCTACAACGAcgttgcggg (SEQ ID NO:3) or 5'- gcggggacaGGCTAGCTACAACGAcagctgcat (SEQ ID NO:10). 20. A method as claimed in claim 18 in which the DNAzyme has the sequence: 5'-ccgcggccaGGCTAGCTACAACGAcctggacga (SEQ ID NO:8) or 5'-ccgctgccaGGCTAGCTACAACGAcccggacgt (SEQ ID NO:9). 21. A method as claimed in any one of claims 13 to 19, wherein the 3'-end nucleotide residue of the DNAzyme is inverted in the binding domain contiguous with the 3' end of the catalytic domain. 22. A method as claimed in any one of claims 1 to 21 which further comprises administering one or more additional anti-cancer agents. 23. A method for inhibiting the growth or proliferation of a tumour cell, the method comprising contacting a tumour cell with an agent which inhibits induction of EGR, an agent which decreases expression of EGR or an agent which decreases the nuclear accumulation or activity of EGR. 24. A tumour cell which has been transformed by introducing into the cell a nucleic acid molecule, the nucleic acid molecule comprising or encoding (i) an agent which inhibits induction of EGR, (ii) an agent which decreases expression of EGR, or (iii) an agent which decreases the nuclear accumulation or activity of EGR. 25. A method of screening for an agent which inhibits angiogenesis, the method comprising testing a putative agent for the ability to inhibit induction of EGR, decrease expression of EGR or decrease the nuclear accumulation or activity of EGR.

Inventors: KHACHIGIAN LEVON MICHAEL, KHACHIGIAN, LEVON, MICHAEL
Applicants: KHACHIGIAN LEVON MICHAEL, UNISEARCH LTD, KHACHIGIAN, LEVON, MICHAEL, UNISEARCH LIMITED
Application year: 2000
Main classification: A61K48
IPC codes: A61K31, A61K38, A61K45, A61K48, A61P35, A61P43, C07K14, C12N5, C12N15, C12Q1, G01N33