USE OF HUMAN CHORIONIC GONADOTROPIN IN THE TREATMENT OF KAPOSI'S SARCOMA

Abstract: The use of hCG Beta-core or hCG fragments, deglycosylated hCG in the treatment of Kaposi's sarcoma is described. Inhibition of tumour production or regression on a variety of KS cell lines is shown. Purified hCG preparations do not inhibit the growth of KS cell lines.

Description: USE OF HUMAN CHORIONIC GONADOTROPIN TN THE TREATMENT OF KAPOSI'S SARCOMA FIELD OF THE INVENTION The present invention relates to the use of hCG fragments or deglycosylated hCG in the treatment of Kaposi's sarcoma. In particular the invention relates to the use of hCG Beta-core in the treatment of Kaposi's sarcoma. BACKGROUND ART Kaposi's sarcoma (KS) is a neoplastic disease characterised by highly vascularized lesions, closely related with epidemic HIV and which occasionally occurs in patients who underwent transplantation, as a consequence of the iminunosuppression. KS occurs more often in men than in women and HIV-associated KS has a high occurrence in homosexual men. Most cultures of KS tumours yield cells with properties of hyperplastic (not malignant) endothelial cells under the control of several cytokines. hCG is a hormone secreted by the placenta as well as by a number of various other tissues, normal and neoplastic ones. It is secreted and acts so in both an endocrine and paracrine way. hCG is heterodimer consisting of an α-subunit and a β-subunit . Surprisingly, each of them shares a structural feature, the so called cystine-knot motif, with several growth factors (NGF, PDGF and others) that are otherwise unrelated to HCG or to the family of glycoprotein hormones, as it has been recently elucidated by crystal structure analysis of deglycosylated HCG. Until now, there is only one receptor known that binds with high affinity ( =t 0.01 μM) hCG, but also luteinising hormone (LH), that is almost identical to hCG, except for a C terminal extension in hCG. This receptor, referred tυ as the LH/hCG-R, as well as those of the other glycoprotein hormones, has been recently cloned and results to belong to the superfamily of 7-transmembrane helix/G protein-coupled receptors, from which it is however distinct due to the long extracellular domain, acting as the ligand capturing element. Such kind of receptors is encoded by a mosaic gene, consisting of 10 exons, representing 1 1 of the so called leucine rich repeats (LRM), and an I I th exon, representing 3 LRM's and the entire transmembrane module. The ensemble of ihe 14 LRM's is currently thought to foπn a horse-shoe structure " embracing" the ligand The receptor of glycoprotein hormones binds only the respective entire hormone, but not a single subunit. The circulating hormone is in the subnanomolar range, as are the affinity for the respective receptor Only during early pregnancy, the blood levels of hCG rise up to suprananomolar levels, and a fraction (about = 0 001 ) occurs also as free subunit Besides dissociated subunits, a variety of other metabolic forms of hCG, particularly in urine, can be found, such as glycosylation and sialylation variants (isoforms), nicked hCG and a particular fragment oϊ β subunit called " Beta-core" Such fragment has been purified by affinity extraction by using monoclonal antibodies (Birken et al., Endocrinology, 123 ' 572-583, 1988) The amino acid sequence of the fragment has been determined Beta-core consists of two polypeptides, bound by disulphide bridges, which correspond to residues 6-40 and 55-92 of hCG β-subunit ln addition to the above mentioned isoforms, deglycosylated hCG can be obtained by different chemical and/or biotechnological ways as described, for example, by Kalyan e Bahl, J Biol Chem 258 67-74, 1983 Beta-core, as deglycosylated hCG or the single isolated subunits, does not show hCG-like biological activity, but represents a major form of immunoreactive hCG and can contaminate pharmaceutical preparation of urinary hCG Lunardi-lskandar et al , Nature, 375 64-68, 1995 have shown that hCG and the hCG β-subunit inhibit the growth of KS cell lines derived from Kaposi's sarcoma, and inhibit tumour production by such cell lines in nude mice Regression of Kaposi's sarcoma has been shown in two women during pregnancy, when the level of such hormone is high DISCLOSURE OF TH E INVENTION We have now found that membranes of KS cells as defined above do not contain the specific hCG/hLH receptor, whereas they contain binding sites of Beta-core and deglycosylated hCG and we hypothesise that impurities contained in hCG preparations, hCG fragments or degradation products, such as Beta-core itself and/or deglycosylated hCG and/or fragments which do not bind the hCG receptor and do not exert hCG-like biological activity are responsible for the in vivo and in vitro activities found by Lunardi- lskandar Other fragments or degradation products of hCG comprising all or part of the Beta-core region can be responsible for this activity as well Impure luteinising hormone (LH), its β-subunit and Beta-core can be also used for killing or inhibit KS cell lines, due to the almost identity of LH and hCG sequences, as reported above Other tumoral forms can be equally treated with Beta-core or with deglycosylated hCG/LH Object of the present invention is, therefore, the use of hCG fragments or degradation products which do not bind the hCG receptor and do not exert hCG-like biological activity for the preparation of a medicament for the treatment of Kaposi's sarcoma or other tumoral forms In particular, the hCG fragments are hCG Beta-core, hCG fragments containing all or part of the Beta-core sequence, deglycosylated hCG or deglycosylated LH ln the course of our study on the effect of hCG and its derivatives on KS cells, it has been observed that hCG does not bind to KS membranes, whereas a low affinity binding at nanomolar concentration has been evidenced when using deglycosylated hCG and hCG Beta-core We have further analysed lour diffei ent specimens of KS, obtained by informed consent of four different HIV patients, in order to verify the presence of LH hCG receptor The specimens have been histopathologically verified By using saturation analysis with l25 l-hCG, a specific binding has not been detected in any of such KS samples, although the total membrane protein was the same as in of rat testis membranes used as positive control for LH/hCG-R We have also analysed four different epidemic KS cell lines for evidencing mRNA expression of LH/hCG receptor using reverse transcription PCR By using a pair of primers for the ninth and eleventh exon, mRNA expression of LH/hCG-R has not been evidenced in any ofthe four KS cell lines, whereas human testis resulted clearly positive We thus come to the conclusion that the growth inhibition of KS Y- l cell line (Lunardi-lskandar et al.) in the pregnant nude mice or in nude mice treated with hCG is mediated by a mechanism distinct from the classical interaction with the LH/hCG-R or by non-LH-hCG substance, which were possibly present in the preparations or in the in vivo settings used in those experiments A recombinant Beta-core molecule can also be engineered in order to evaluate its potential biological activity. The Beta-core fragment has, among other things, a loop deletion (the " Keutmann loop" ) at position Thr40 and Val 55. This loop can be replaced by a smaller one with a high probability to energetically favour a Beta-turn loop formation The distance between ihe Cu of Thr40 and VaI55 is 7 2 A A linker such as ProGlyAla was chosen and appeared to fit well the gap between these residues The ProGlyAla linker easily favours a turn formation Another characteπstic of the Beta-core fragment is the presence of a free and accessible cysteine at position 2 1. A recombinant Beta-core molecule containing a free cysteine might tend to make a disulfide homodimer molecule A free cysteine might also represent an opportunity to specifically modify the molecule by coupling to biodegradable polymer such as PEG. As it is still unclear whether the potential biological activity of the Beta-core fragment is related to its monomeric or dimeric form, the native recombinant Beta-core molecule and its mutant Cys2 l -Ala rBeta-core molecule are best expressed in CHO cells Example 1 Binding to Kaposi's Sarcoma membranes Membranes extracted from biopsies of KS were incubated in increasing concentration, from 1 x 10 - ό to I x l Ox" 1 0 M, of l25 l-hCG or HCG β subunit, deglycosylated hCG, hCG Beta-core, followed by incubation with an l25 l- labelled antibody to hCG Beta-core The same substances have been tested on rat testis membranes, as control It was observed that KS membranes did not bind hCG, whereas such binding occurred at high affinity on rat lestis membranes Deglycosylated hCG and hCG Beta-core showed a low affinity binding at nanomolar concentration with both KS and rat testis membranes mRNA Isolation ln order to verify whether mRNA expression of LH/hCG receptor occurs, reverse transcription PCR was used starting from mRNA isolated from four different epidemic KS cell lines, named M7/3, M5/ 1 , M7/KK2 and KS 10 (Table I ) From all samples mRNA was extracted using a solid phase affinity chromatography on poly-T resin, according to the manufacturer's instructions (R&D Systems Europe Ltd. " mini message maker" RNA Isolation Kit) The cells were harvested, washed twice with 25 ml of phosphate buffer (PBS) at room temperature (1000 rpm, 5 min, Beckman TJ6) and the pellets were frozen in liquid nitrogen. The pellets were then solubilized with I ml of " lysis buffer" (if necessary, several harvests were pooled), and 50 μl oligo-dT latex beads were added, and incubated at room temperature for 10 minutes Beads were spun down ( 12000 rpm, 5 min), transferred to a " spin column" , that was washed twice with " wash buffer" ( 12000 rpm, 30 sec and 2 min, respectively), and finally eluted with 50 μl 70°C " elution buffer" RNA yield was estimated by OD 2() o/OD 2 s (l nm method Eluates were stored at -80° C cDNA preparation Aliquots of 200-500 ng mRNA were reverse transcribed using the following procedure 1 - 10 μl mRNA eluate were mixed with I μl oligo-dT- 15 solution (500 ng/ml, PROMEGA), incubated 10 min at 70°C, cooled on ice, centrifuged ( 12000 rpm, 6 sec) Thereafter, 4 μl 5X " 1 st strand buffer" (PROMEGA kit), 2 μl 0 1 M DTT, I μl dNTP's (10 mM each) were added (on ice) and the mixture incubated at 37°C for 2 min Then, 1 μl reverse transcriptase (200 U/μl) solution was added and allowed to react at 37°C for 1 5 hrs The enzyme was inactivated by heating the mixture to 70°C for 1 5 min ln some cases (to ensure single strandedness), cDNA's were treated with RNAse H ( 1 5 U/μl, PROMEGA). cD A's were stored at -20°C RT-PCR of hCG-R and β2 Microulobulin To aliquots of 1 -6 μl (representing 20 ng cDNA) were added 2 5 μl primer solutions ( 100 ng/μl), 1 μl dNTP ( 10 mM each), 5 μl I OX PCR buffer supplemented with 1.5 M MgCI 2 and 0 5 μl Taq polymerase (2 U/μl, DyNAZyme™ 11, FINNZYMES Oy, Espoo, Finland) The mixture was incubated 2 min at 94°C, and then in 35 cycles 50 sec at 94°C, 1 min at 53°C and 25 sec at 73°C for hCG-R PCR using a thermocycler from Biometra (Gottingen, Germany) For β2 microglobulin-PCR annealing temperature was 56°C and only 23 cycles were done For hCG-R PCR the following primer pair was used: 5'-CCTGGAGGCCACGTTGACTTACCCCAG-3' (primer "hCG-R 5") 5'-CCTAAGGAAGTCATAGCCC ATAATG-3 ' (primer "hCG-R 6") The former matches a portion of exon 9 and the latter one portion of exon 1 1 , thus covering a stretch of 285 bp of the hCG-R cDNA The primer were obtained from MWG-Biotech (Ebersberg, Germany) For PCR of β2 microglobulin, the following primer pair was used 5'-ATGCCTGCCGTGTGAACCATGT-3 ' (primer β2 micro sense) 5'-AGAGCTACCTGTGGAGCAACCT-3 ' (primer β2 micro antisense) These primers match a portion of exon 2 and 4 respectively Aliquots of 10 μl of each of the PCR products were analysed by 1 ,5% agarose gel electrophoresis using ethidium bromide staining mRNA expression of the LH/hCG receptor was not evidenced in any of the four KS cell lines, whereas human testis, used as a control, clearly expressed the LH/hCG-R mRNA Table I CELL CULTURE PASSAGE CELL NUMBER IN in RNA YIELD LINE MEDIUM NUMBER CULTURE (μg) M7/3 A 9 6X10E6 1XI0E7 089 4X10E6 4X10E6 4X10E6 190 M5/1 A 7 2X10E6 - 10 2X10E6 - 11 3X10E6 13 1X10E6 140 M7KK2 A 6 7X10E6 096 8 8X10E6 - 9 2X10E6 1.28 11 5X10E6 - 12 5X10E6 160 KS10 B 15 1X10E7 096 18 8X10E6 - 20 2X10E7 560 Medium A' DMEM (Gibco), supplemented with 10% of FCS (Gibco), Penicillin (100 IU/ml) and Streptomycin (10 μg/ml) Medium B 50% of RPMI 1640 + 50% DMEM (Gibco), supplemented with 10% FCS (Gibco), Penicillin (100 IU/ml), Streptomycin (10 μg/ml), Glutamine (40 mM) REFERENCES TO TABLE I M7/3; M5/1. M7KK2 These KS cell lines from different patients were all prepared according to M Sturzl et al , Oncogene 10 2007-2016, 1995 KS10 R Benellietal, Cancer Letteis, 100 125-132, 1996 Example 2 Inhibition of Kaposi's sarcoma cell lines by impure hCG as opposed to non- inhibition by purified recombinant hCG Materials and Methods Cell Culture Cell lines of the previous example and additional cell line KS 1 1 (F Bussolino et al., J Clin Invest 96 940-952, 1995) were grown under the tissue culture conditions described in Table 1 , however without streptomycin and penicillin hCG preparations Urinary hCG 10 000 lU/ampoule, CG- 10, Sigma Chemical, St Louis, MO, Recombinant hCG prepared according to J Lustbader et al , J Biol Chem , 29 14204- 14212, 1987 Cell Proliferation/Viability Assa In order to monitor cell proliferation/viability, the following procedure was used, which is based on Boehringer Mannheim WST- I reagent (Cat# 1644 807) This procedure colorimetrically measures the generation of a formazan salt in viable cells upon addition of the tetrazolium salt WST- 1 (4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H- 5-tetrazolio]- l ,3-benzene disulfonate) Dehydrogenases (i e the " succinate-tetrazolium reductase system" , E.C. 1 3 99 1 , a member of the respiratory chain enzyme system) present in mitochondria of viable cells cleave WST- I to its dark red formazan derivative This derivative is chemically quite stable and water-soluble and thus can be directly measured in the culture medium An augmentation in " WST- I " activity correlates with an increase in the number of viable and thus metabolically active cells. The assay is very sensitive and can be performed with 1 -2X 10 4 cells per well, thus in a 96 well microtiter plate Results Influence of hCG preparations on KS cells in culture Cells were cultivated under standard conditions, as described earlier, distributed onto 96 well plates ( 1 -2X 10 ' cells per well) and grown for 24 hours The experiments described below refer to passage numbers 22-25 for KS I 1 cells, and passage # 8- 10 for M7kk2 cells Thereafter, medium was changed for one containing only 0.5% FCS instead of 10% Aftei anothei 1 -2 houi s cultivation, c ugs weie added and cells incubated foi 24 hours Finally, WST- I was added and 4 houi s latei , the formation of its i ed deπvative was monitored at 450 nm in a mici otitei well leadei All experiments were performed in quadruplicate Readings weie evaluated by Student's T tests CG 10, a urinary hCG preparation made by Sigma inhibited cell viability (at a dose of 800 nM onwards, 1600 nM being the pieferred dosage) Light microscopy examination, perfomied by means of an inverted microscope, showed that all cells were rounded or dead oi fragmented into debus, in this ordei , depending on the time elapsed after addition of drug Recombinant hCG. however, when tested under the same conditions, was not inhibitory, nor did it show cell proliferation enhancing effect Example 3 Inhibition of Kaposi's saicoma cell lines by Beta-core Materials and Methods Human Umbilical Vein Endothelial Cells (HUVEC) wei e obtained from ATCC (Rockville, Maryland, USA) and grown on gelatine pre-coated flasks (Sigma, 1% in distilled water) in M l 99 media supplemented with 10% heat inactivated (hi) FCS, Heparin (ICN, lOOμg/ml) and Endothelial Cell Growth Supplement (60μg/mg) Urinary hCG (6 000 IU/mg) was prepaied from crude urinary hCG as described in Lunardi-lskandar, ( 1995) hCG β subunit according to the same method starting from r-hCG hCG Beta-core was piepared according to Bii ken, 1988, with a further purification step by RP-HPLC Establishment of * primary KS-cell cultures KS biopsies were immediately put in RPMI medium supplemented with amphotericin B (2,5μg ml), penicillin ( lOOU/ml), and streptomycin (50μg/ml) The lesions were then minced in small pieces that weie subsequently used to obtain explants Remaining portions of the biopsies weie enzymatically digested with trypsin (0,25%) for 15 minutes at 37°C, then with Collagenase type 1 (400 U/ml) and type 11 ( 1000 U/ml) (Seromed) in PBS (lacking Calcium and Magnesium) foi 2 hours at 37°C, and again with 0 5% trypsin, 15 minutes at 37°C to disaggieg te the lemaming cell clustei s The cells obtained from enzymatic digestion weie centi ifuged and plated in gelatine coated 25cc flasks Cells weie cultuied usιn» 50% RPMI 1640/50% DMEM medium with 10% hi FCS. The primary (" reactive" ) KS spindle cells were obtained from an epidemic (AIDS 1ST KS 20) and a iatrogenic (1ST KS 26) biopsies using enzymatic digestion The biopsies used for primary cultures were positive for HHV-8 Kaposi associated herpes virus Cells were characterised and found similar to previously described spindle cells (F. Bussolino, 1995). Establishment of the KS IMM cell line and its characterisation One KS biopsy (from a iatrogenic patient different from KS 26) gave rise to two different cell populations , " reactive" spindle cells, using enzymatic digestion, and a population of smaller cells arising from an explant These cells were isolated and expanded; they grew rapidly with a doubling time of 24 hours and showed no signs of senescence after numerous passages oϊ in vitro culture This apparently " immortal" KS cell line was termed KS IMM. The KS IMM cells were cultured in simple DMEM 10% hi FCS. Metabolic growth assays: Cells ( I x lOVwell for KS IMM, 2 x l OVwell for KS spindle ceils and HUVE cells) were plated into 96-well microliter plates with 150 μl complete medium. After 24 hours hCG or its derivatives were added dissolved in 150 μl of complete medium. Urinary hCG, β-subunit and Beta-core were used at different concentrations (40μg/ml, lOμg/ml and 5μg/ml respectively) in order to have approximately the same molar concentration, the treatment was repeated once every 48 hours (urinary hCG) or every 24 hours (β-subunit and Beta-core) At the end of the treatment cells were incubated at 37°C for 4 hours with MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (thiazolyl blue)] by adding 50 μl of a 2mg/ml solution (in PBS) to each well. The plate was centrifuged for 10 minutes at 400 x g and the solution with MTT removed. To elute the chromogen, 50 μl oϊ DMSO at 37°C were added, the plate was then incubated for 5 minutes at room temperature in the dark; absorbance (OD) was measured at 540 nm with a scanning mulliwell spectrophotomer within 10 minutes after the addition of DMSO To assess the specificity of the inhibitory activity of hCG and of its derivatives in the MTT assay we used specific neutralising antibodies (sheep anti hCG antibodies and rabbit anti β-subunit antibodies, Medix Biotech Inc.). Tests were performed ■ ng a compound/antibody molar ratio of 1 : 10 Results Effect of hCG and related derivatives on KS cell growth The effects of urinary hCG, the β-subunit and the purified Beta-core on the growth of " reactive" KS spindle cells, KS IMM and HUVE cells were tested. KS spindle cells were partially growth inhibited by urinary hCG. The β-subunit of hCG gave an even greater inhibition. The most potent effect was obtained with the Beta-core fragment, which blocked growth of spindle cells and had no effect on growth of cultured normal human umbilical vein endothelial cells (HUVEC) used as a control (Fig. I ). The Beta-core was active on KS spindle cells also at 0 5 μg/ml concentration (not shown). Antiserum to hCG was able to counteract hCG inhibition of KS cell growth, whereas non-immune serum had no effect. In a parallel experiment, KS IMM cell growth was inhibited by urinary hCG (20 μg/ml) with decrements in growth rate similar to the KS spindle cells The β-subunit and Beta-core of hCG retained the inhibitory effect on KS IMM cell growth at an approximately 10 fold Iower molar concentration showing more pronounced inhibition as compared to the intact hCG molecule. This was particularly evident for the Beta-core fragment, which showed the strongest inhibitory effect on KS IMM cells and the " reactive" KS spindle cells. The Beta-core was active at ten fold Iower molar concentration than that reported by Lunardi-lskandar for the β-subunit [Lunardi- Iskandar, 1995]. Growth of control HUVE endothelial cells was not inhibited. In conclusion, all tested forms of hCG, were able to inhibit KS cells growth, the Beta-core being the most effective, also al Iower doses Growth rates obtained using MTT were confirmed by data obtained by direct cell counts with Trypan Blue.

Claims: CLAIMS 1 . Use of hCG fragments or degradation products which do not bind the hCG receptor and do not exert hCG-like biological activity in the preparation of a medicament for the treatment of Kaposis's sarcoma or other tumoral forms. 2. Use as claimed in claim 1, wherein the hCG fragments are hCG Beta-core or hCG fragments containing all or part of the hCG Beta-core. 3. Use as claimed in claim 2, wherein the hCG fragment is hCG Beta-core . 4. Use of deglycosylated hCG or deglycosylated LH for the preparation of a medicament for the treatment of Kaposi's sarcoma or other tumoral forms. 5. Use of mixtures containing at least two polypeptides selected among: hCG Beta-core or hCG fragments containing all or part of the hCG Beta-core sequence, deglycosylated hCG, deglycosylated LH, for the preparation of a medicameni for the treatment of Kaposi's sarcoma or other tumoral forms.

Inventors: SCHWARZ SIEGFRIED, SCHWARZ, SIEGFRIED
Applicants: APPLIED RESEARCH SYSTEMS, SCHWARZ SIEGFRIED, SCHWARZ, SIEGFRIED
Application year: 1996
Main classification: A61K38
IPC codes: A61K38, A61P35