MUTANT INTERLEUKIN 6 WITH IMPROVED BIOLOGICAL ACTIVITY OVER WILD INTERLEUKIN 6

Abstract: Mutant interleukin 6, characterized by the fact that it has, in the position 176, the amino-acid arginine in place of the amino-acid serine as in wild interleukin 6, and by the fact that it shows greater biological activity than wild interleukin 6. The figure represents the genetic map of the plasmid pBKS IL-6 Ser176Arg containing the nucleotidic sequence coding for mutant interleukin 6 according to the invention, non-glycosilated. This plasmid has been filled in E. coli K12 with the National Collection of Industrial and Marine Bacteria Ltd. on 02/11/1992 under access number NCIMB 40526.

Description: MUTANT INTERLEUKIN 6 WITH IMPROVED BIOLOGICAL ACTIVITY OVER WILD INTERLEUKIN 6 DESCRIPTION The present invention relates to mutant interleukin 6 having a biological activity on human cells that is significantly superior to that shown by wild interleukin 6. As is known, interleukin 6 (hereinafter also indicated as IL-6) is a 184 amino acid polypeptide postulated to belong to the class of helical cytokines. IL-6 is a multi-functional cytokine produced by a variety of cell types. It acts as a differentiation and growth factor on cells of various types, for example cells of the immune system, hepatocytes, kidney cells, hematopoietic stem cells, keratinocytes and neurons (Akira, S., Hirano, T. Taga, T. and Kishimoto, T. (1990) FASEB J. 4, 2861-2867; Hirano, T. (1991) International J. of Cell Cloning 9, 166-186; Hirano, T. , Akira, S., Taga, T. and Kishimoto, T. (1990) Immunol. Today 11, 443-449; Van Snick, J. , Cayphas, S., Vink, A. , Uyttenhove C. , Coulie, P.G. and Simpson, R.J. (1986) Proc. Natl. Acad. Sci. USA, 83, 9679-9683). The three-dimensional model of human interleukin 6 (hIL-6) is based on the similarity of its hydrophobicity pattern with that of other cytokines and on the x-ray determination of the structure of proteins such as, for example, the growth hormone, interleukin 2, interleukin 4, interferon-beta and the Granulocyte Macrophage Colony Stimulating Factor. The resulting model, that is to say a bundle of four alpha-helices (A, B, C and D) with up-up-down-down topology connected by means of three loops, suggests that the nine carboxy-terminal amino acids could be folded into an alpha-helix or a ' non-helicoidal conformation interacting with residues in the A-B loop could be adopted. Experiments carried out during the present invention favour this second, non-helicoidal conformation. In this region others have already underlined the importance from a point of view of biological activity of the arginine in position 182 and methionine in position 184. It has now been unexpectedly found that the mutant interleukin 6, subject of the present invention, with the amino acid arginine in position 176, in place of the amino acid serine as is the case in wild interleukin 6, shows a biological activity significantly higher than that of wild interleukin 6. This is an extremely important result because of its effects in the field of medicine. The improved biological activity of mutant interleukin 6 according to the present invention makes it possible to use therapeutic doses between 2 and 4 times lower than those required when using wild interleukin 6 in the treatment of a number of serious diseases. In fact, interleukin 6 has important and promising applications in the treatment of breast cancer, leukemia, infectious diseases and diseases connected with disorders connected with bone marrow stem cells. Subject of the present invention is therefore mutant interleukin 6, characterized in that it has, in position 176, the amino acid arginine instead of the amino acid serine as in wild interleukin 6, and in that it shows biological activity on human cells superior to that of wild interleukin 6. In particular, the biological activity of mutant interleukin 6 according to the present invention can be between three and five times higher than that of wild type interleukin 6. The present invention also relates to a non- glycosilated polypeptide comprising the amino acid sequence of mutant interleukin 6 by substitution Ser 176 Arg. The invention also relates to recombinant vectors comprising a DNA sequence coding for said polypeptide, and to transformed microorganisms containing it. The invention also relates to a process for preparation of said non-glycosilated polypeptide by culture of said transformed microorganisms and subsequent recovery of the polypeptide. Finally, the invention also relates to pharmaceutical compositions - for treatment of breast cancer, leukemia, infectious diseases connected with disorders of the bone marrow stem cells, and thrombocytopenia - containing, as active principle, mutant interleukin 6 with the amino acid arginine in position 176. Such compounds can be administered I.V. The increased biological activity of mutant interleukin 6 according to the present invention is to be related to the increase affinity for the human interleukin 6 receptor, in the C-terminal region, due to the substitution, as residue 176, of serine with arginine. The sole figure enclosed represents the genetic map of the plasmid pBKS IL-6 Serl76Arg containing the nucleotidic sequence coding for mutant interleukin 6 according to the invention, non-glycosilated. This plasmid has been deposited in E.coli K12 with The National Collection of Industrial and Marine Bacteria Ltd. on 02/11/1992 under access number NCIMB 40526. Up to this point a general description has been given of the present invention. With the aid of the following examples, a more detailed description will now be given of embodiments thereof, to give a clearer understanding of its objects, characteristics, advantages and methods of application. EXAMPLE 1 Preparation of mutant interleukin 6 by substitution Serl76Arq Serl76Arg substitution interleukin 6 was generated using the PCR strategy (as illustrated in Fontaine, V. , Savino, R. , Arcone, R. , Brakenhoff, J.P.J., Content, J. and Ciliberto, G. (1992) Eur. J. Bioche ; see in Purification of the amplified fragments, ligation in the pBKS IL-6 vector, screening and characterization of the mutant plasmids were carried out as described in the above mentioned work by Fontaine et al. Some of the mutant cDNAs were subcloned into E. coli expression vector pT7.7 (Studier, F. W. and Moffatt, B.A. (1986) J. Mol. Biol. 189, 113-130); this was accomplished by excising the chosen cDNAs with Spel and Xhol and ligating them in pT7.7 cut with Xbal (compatible with Spel) and Sail (compatible with Xhol) . The mutant protein was expressed in two different ways, which will be indicated with a) and b) in the following. a) In vitro transcription and translation. All mutant plasmids and pBKS IL-6 were linearized using Asp 718. Approximately one ug of DNA template was transcribed using the mCAP RNA capping kit (Stratagene, La Jolla, Ca) according to the instructions furnished by the manufacturer. The transcribed RNAs were translated with rabbit reticolocytis lysate (Promega) for 90 minutes at 30"C in presence of 35 S-methionine (Amersham) ; 3 /ul of the translation cocktail were analyzed by electrophoresis in 15% SDS-PAGE (as described in Fiorillo, M. T. , Cabibbo, A., Iacopetti, P., Fattori E. and Ciliberto, G. (1992) Eur. J. 22, 2609-2615). After exposure, the bands corresponding to wild type and mutant hIL-6 were excised from the polyacrylamide gel and their radioactivity was determined. The values were normalized taking into account the number of methionines present, b) Production in E.coli. Wild type and mutant hIL-6 were expressed in E. coli and purified exactly as described in Arcone, R. , Pucci, P., Zappatosta, F. , Fontaine, V., Malorni, A., Marino, G. and Ciliberto, G. (1991) Eur. J. Biochem 198, 541-547; and in Fiorillo, M. T. , Cabibbo, A., Iacopetti, P., Fattori, E. and Ciliberto, G. (1992) Eur. J. Immunol. 22, 2609-2615. The purity of the proteins was checked by electrophoresis in 15% SDS-PAGE and staining with Comassie Brilliant blue R-250. Their amount was quantified by Bio-Rad protein assay (Bio- Rad) . EXAMPLE 2 Biological assays The biological activity of the mutant of interest was determined first of all on cells of human origin. The activity of hIL-6 on human cells was assayed for its ability to enhance transcription from acute phase gene promoters in cells of hepatic origin (Morrone, G. , Ciliberto, G. , Oliviero, S., Arcone, R. , Dente, L. , Content, J. and Cortese, R. (1988) J. Biol. Chem. 263, 12554-12558) . The mutant has therefore been tested as regards its ability to induce CAT (chloramphenicol- acetyltransferase) activity from a fusion of C-reactive protein promotor (CRP) and CAT transfected into the human hepatoma cell line Hep3B (Arcone, R. , Gualandi, G. and Ciliberto, G. (1988) Nucleic Acids Res., 16, 3195-3207; Fiorillo, M. T. , Cabibbo, A., Iacopetti, P., Fattori, E., Ciliberto, G. (1992) Eur. J. Immunol. 22, 2609-2615) . The results obtained using this system are of particular importance, as they depend on the efficiency of the interaction of cytokine with the homologous receptor system. In particular, human Hep3B cells were transfected with 45-50 /ug of the plasmid -219 CRP-CAT containing the IL-6 responsive element of the CRP promoter gene. Transfection was performed in 20 ml of Dulbecco's Modified Eagle Medium (DMEM, Gibco) supplemented with serum 10% fetal calf and 2 mM L-glutamine using the calcium phosphate precipitation technique (Graham, I.F.L. and Van der Eb, A.J. (1973) Virology 52, 456- 467) . After 16-18 hours, precipitates were removed, cells were trypsinized, pooled, counted, and plated in equal number (10 5 to 3xl0 5 ) in 5 cm diameter petri dishes; 7-9 hours after plating, cells were induced for 36-40 hours with increasing amounts of mutant or wild- type hIL-6. Cell extracts and CAT assays were performed as described by Gorman, C. (1985) in "DNA cloning; a practical approach" (Glover, M.D., ed.) pages 143-190, IRL Press, Oxford. The assay was carried out in duplicate (in triplicate in case of wild type hIL-6) with serial dilutions of two to four independent preparations of mutant. The activity of the mutant, expressed as a percent of wild type hIL-6, was calculated as the ratio between the amount of wild type hIL-6 and the amount of the mutant under examination necessary to give half maximal stimulation. Giving the biological activity of wild type interleukin 6 to be 100% in this assay, the biological activity of mutant interleukin 6 according to the present invention, with Serl76Arg (S176R) substitution, shows, as reported in the following table 1, a value of 370 + 90%, which is thus a value equal to three to four times that of the wild type protein. TABLE 1 Comparison of receptor binding and biological activity Mutation Biological activity hIL-6R binding (% of wt hIL-6) (% of wt hIL-6) S176R 370 + 90 % 320 ± 87 % Affinity for the soluble hIL-6 receptor of mutant hIL-6 produced in E.coli compared to the observed biological activity. Mutant interleukin 6 according to the present invention has also been tested using the classical HGF (Hybridoma Growth Factor) assay for its ability to stimulate growth of the hIL-6 dependent murine hybridoma cell line 7TD1 (Van Snick, J., Cayphas, S., Vink, A., Uyttenhove, C, Coulie, P.G. and Simpson, R.J. (1986) Proc. Natl. Acad. Sci. USA, 83, 9679-9683). The assay was performed taking into account the indications of Fiorillo, M. T. , Cabibbo, A., Iacopetti, P., Fattori, E. and Ciliberto, G. (1992) Eur. J. Immunol. 22, 2609-2615. In this case also a significant increase in biological activity has been seen in the mutant interleukin 6 with respect to the wild type. SEQUENCE LISTING (1) GENERAL INFORMATION (i) APPLICANT: Istituto di Ricerche di Biologia Molecolare P. Angeletti S.p.A. (ii) TITLE OF INVENTION: MUTANT INTERLEUKIN 6 WITH IMPROVED BIOLOGICAL ACTIVITY OVER WILD INTERLEUKIN 6 (ϋi) NUMBER OF SEQUENCES: 1 (iv) CORRESPONDANCE ADDRESS: (A) ADDRESSEE: Societa Italiana Brevetti S.p.A. (B) STREET: 39 Piazza di Pietra (C) CITY: Rome (D) STATE: ITALY (E) ZIP: 1-00186 (v) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Floppy disk 3.5" 1.44 MBYTES (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS Rev. 5.0 (D) SOFTWARE: Microsoft Wordstar 4.0 (vi) CURRENT APPLICATION DATA: (A) APPLICATION NUMBER: (B) FILING DATE: (C) CLASSIFICATION: (VU) PRIOR APPLICATION DATA: (A) APPLICATION NUMBER: IT RM92A000809 (B) FILING DATE: 06 November 1992 (viii) ATTORNEY INFORMATION: (A) NAME: DI CERBO, Mario (ix) TELECOMMUNICATION INFORMATION: (A) TELEPHONE: (39) 6 6785941 (B) TELEFAX: (39) 6 6794692 (C) TELEX: 612287 ROPAT (2) INFORMATION FOR SEQ ID NO: 1 (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 555 base pair (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULAR TYPE: cDNA (iii) HYPOTHETICAL: no (iv) ANTISENSE: no (vi) ORIGINAL SOURCE: (A) ORGANISM: Homo sapiens (B) DEVELOPMENT STAGE: Adult (C) CELL TYPE: monocyte (vii) IMMEDIATE SOURCE: (A) LIBRARY: cDNA (B) CLONE: pB.β2.21 (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 1: CCA GTA CCC CCA GGA GAA GAT TCC AAA GAT GTA GCC GCC CCA CAC AGA 48 Pro Val Pro Pro Gly Glu Asp Ser Lys Asp Val Ala Ala Pro His Arg 1 5 10 15 CAG CCA CTC ACC TCT TCA GAA CGA ATT GAC AAA CAA ATT CGG TAC ATC 96 Gin Pro Leu Thr Ser Ser Glu Arg l ie Asp Lys Gin l ie Arg Tyr l ie 20 25 ' 30 CTC GAC GGC ATC TCA GCC CTG AGA AAG GAG ACA TGT AAC AAG AGT AAC 144 Leu Asp Gly l ie Ser Ala Leu Arg Lys Glu Thr Cys Asn Lys Ser Asn 35 40 45 ATG TGT GAA AGC AGC AAA GAG GCA CTG GCA GAA AAC AAC CTG AAC CTT 192 Met Cys Glu Ser Ser Lys Glu Ala Leu Ala Glu Asn Asn Leu Asn Leu 50 55 60 CCA AAG ATG GCT GAA AAA GAT GGA TGC TTC CAA TCT GGA TTC AAT GAG 240 Pro Lys Met Ala Glu Lys Asp Gly Cys Phe Gin Ser Gly Phe Asn Glu 65 70 75 80 GAG ACT TGC CTG GTG AAA ATC ATC ACT GGT CTT TTG GAG TTT GAG GTA 288 Glu Thr Cys Leu Val Lys l ie l ie Thr Gly Leu Leu Glu Phe Glu Val 85 90 95 TAC CTA GAG TAC CTC CAG AAC AGA TTT GAG AGT AGT GAG GAA CAA GCC 336 Tyr Leu Glu Tyr Leu Gin Asn Arg Phe Glu Ser Ser Glu Glu Gin Ala 100 105 110 AGA GCT GTC CAG ATG AGT ACA AAA GTC CTG ATC CAG TTC CTG CAG AAA 384 Arg Ala Val Gin Met Ser Thr Lys Val Leu l ie Gin Phe Leu Gin Lys 115 120 125 AAG GCA AAG AAT CTA GAT GCA ATA ACC ACC CCT GAC CCA ACC ACA AAT 432 Lys Ala Lys Asn Leu Asp Ala l ie Thr Thr Pro Asp Pro Thr Thr Asn 130 135 140 GCC AGC CTG CTG ACG AAG CTG CAG GCA CAG AAC CAG TGG CTG CAG GAC 480 Ala Ser Leu Leu Thr Lys Leu Gin Ala Gin Asn Gin Trp Leu Gin Asp 145 150 155 160 ATG ACA ACT CAT CTC ATT CTG CGG AGC TTT AAG GAG TTC CTG CAG TCC 528 Met Thr Thr His Leu l ie Leu Arg Ser Phe Lys Glu Phe Leu Gin Ser 165 170 175 AGC CTG AGG GCT CTT CGG CAA ATG TAG 555 Ser Leu Arg Ala Leu Arg Gin Met * 180

Claims: CLAIMS 1. Mutant interleukin 6, characterized in that it has, in position 176, the amino acid arginine, in place of the amino acid serine as in wild interleukin 6, and in that it shows biological activity on human cells superior to that of wild type interleukin 6. 2. Mutant interleukin 6 according to claim 1, which exhibits a biological activity on human cells between three and five times higher than that of wild type interleukin 6. 3. Non-glycosilated polypeptide comprising the amino acid sequence of mutant interleukin 6 according to claims 1 and 2. 4. Recombinant vector comprising a DNA sequence coding for the polypeptide according to claim 3. 5. Recombinant vector according to claim 4, characterized in that it consists of plasmid pBKS IL-6 Serl76Arg deposited in E. coli K12 with The National Collection of Industrial and Marine Bacteria Ltd. on 02/11/1992 under access number NCIMB 40526. 6. Transformed microorganism, characterized in that it contains the recombinant vector according to claim 4 or 5. 7. Transformed microorganism according to claim 6, characterized in that it is E.coli, in particular E.coli K12. 8. Pharmaceutical compositions, suitable for the treatment of breast cancer, leukemia, infectious diseases and diseases connected with disorders of the bone marrow stem cells and thrombocytopenia, characterized by the fact of containing, as active principle, mutant interleukin 6 according to claims 1 to 3, and characterized by the fact of being administered I.V. 9. Process for the preparation of the non- glycosilated polypeptide, comprising the amino acid sequence of mutant interleukin 6, according to claim 3 by culture of the transformed microorganisms according to claims 6 and 7 and subsequent recovery of the polypeptide.

Inventors: CILIBERTO GENNARO, SAVINO ROCCO, CILIBERTO, GENNARO, SAVINO, ROCCO
Applicants: ANGELETTI P IST RICHERCHE BIO, CILIBERTO GENNARO, SAVINO ROCCO, CILIBERTO, GENNARO, ISTITUTO DI RICERCHE DI BIOLOGIA MOLECOLARE P. ANG, SAVINO, ROCCO
Application year: 1993
Main classification: C07K15
IPC codes: A61K38, C07K14, C12N1, C12N15, C12P21, C12R1