Expression Of Recombinant Human Interleukin 24 And Identification Of Its Biological Activity

The melanoma differentiation associated gene-7 (mda-7 gene) was identified through subtraction hybridization from a human melanoma cell line by P.B.Fisher in 1995. It is now evident that mda-7 is expressed in normal melanocytes and its expression decreases progressively during the process of melanoma transformation and progression to metastatic disease. Since the expression of mda-7 is correlated with induction of irreversible growth arrest, cancer reversion and terminal differentiation in human melanoma cells. Caudell et al confirmed MDA-7 that has cytokine nature, and therefore re-designated interleukin-24, belongs to the IL-10 family of cytokines. Up to now, a large body of data has accumulated to demonstrate that IL-24 results in growth suppression and induction of apoptosis in a broad range of cancer cells, but not in normal human cells, which is independent of classic tumor suppressor genes such as p53,Rb and pl6. As cytokine, IL-24 not only can activite immunocell, induce production of cytokine, regulate whole antitumor immune reaction and hematopoietic system, but also selectively induce apoptosis of tumor. .cells and direct repress hyperplasy netustasis of tumor cells. According to this data, it has been speculated that IL-24 might function as a tumor suppressor, in addition to its cytokine functions, making it a dual-function molecule. The apparently unique and intriguing properties of IL-24, particularly its potential as an anticancer gene therapeutic, has made it the focus of research of an increasing number of groups. The gene therapy agent Ad.IL-24 was developed by Introgen corporation and The university of Texas, with the trade name of INGN 241. In addition, the present study documented that Ad. IL-24 (INGN 241) could induce apoptosis in a large percentage of tumor volume following intratumoral administration. The deep research on the mechanism and clinical trials of IL-24 has not only proved its biological activities and curative effects, but also greatly increased the demands of production of IL-24. So it is necessary to prepare large quantity of recombinant IL-24 with high purity and bioactivity by genetic engineering technique. By fusing protein Trx-IL-24 through E.coli.expression system, producing of recombinant protein IL-24 from Trx-IL-24 and glycoprotein rIL-24 through P.pastoris expression system, this research may build a footstone for the future study about the mechanism of induction cancer apoptosis and cancer therapy.