Study On Targeting Oncolytic Adenovirus That TRAIL Linked Smac With IETD For Cancer Therapy

The causes of cancer are often associated with multiple genes mutation. Effective gene therapy for cancer should be multiple therapeutic genes of multitarget suppression. In theory, a dual genes combination strategy simultaneously targeting multiple defective genes would be more effective and complete than single-gene strategy. But the most critical issue is the lack of an ideal connexon, which can express dual genes effectively. Several strategies have been described to co-express two or more genes by IRES or self-cleaving peptide FMDV 2A. Since the expression level of transgenes often dramatically affects the therapeutic efficacy. The large size and the imbalance expression of IRESes, and the low self-cleave efficiency of FMDV 2A limit their utility in dual genes therapy. So IETD connexon was introduced for an alternative strategy to guarantee a reliable co-expression.TRAIL and Smac were connected by IETD, and then join in ZD55 system to construct Targeting dual gene-virus ZD55-TRAIL-(IETD)-Smac. When ZD55-TRAIL-(IETD)-Smac infect tumor cells, precursor of caspase-8 can be activated by stress reaction due to duplication of viruses. Activated caspase-8 can recognize and cleave IETD peptide, then generate solitary and competent TRAIL and Smac protein. At the same time, competent TRAIL can further activated caspase-8 precursor, then apoptosis was cascade amplification. TRAIL and Smac have complementary action on co-inhibit tumor cells.Western blot showed that the expression levels of TRAIL and Smac protein from Targeting dual gene-virus ZD55-TRAIL-(IETD)-Smac were nearly equal to these proteins from single-gene virus. MTT assays and CPE experiments showed that ZD55-TRAIL-(IETD)-Smac exhibited higher antitumor effect than ZD55,ZD55-TRAIL,ZD55-Smac and ZD55-TRAIL plus ZD55-Smac, at the same time, it was proved to be very safe to normal cells. Furthermore, ZD55-TRAIL-(IETD)-Smac can dramatically inhibit the volume of the NCI-H460 lung carcinoma in nude mice compared to other viruses.Compare to single gene-virotherapy or single gene-virotherapy alliance, Targeting dual gene-virus ZD55-TRAIL-(IETD)-Smac attain better antitumor effect.This study set up a solid foundation for exploring more effective dual gene-virotherapy.