Effects of G250 promoter controlled conditionally replicative adenovirus expressing Ki67‐siRNA on renal cancer cell

Abstract

Replication-competent adenovirus (RCAd) has been used extensively in cancer gene therapy, and tumor-selection is critical for the use of replication-competent adenovirus. Here we investigated the anti-tumor characterization of oncolytic virus, whose E1A gene is under the control of a renal cell carcinoma specific promoter - the G250 promoter. The constructed oncolytic virus G250-Ki67 is armed with transgene of Ki67-siRNA, and G250-ZD55-Ki67 also with E1B-55 KD deleted. The tumor-specific expression of E1A and Ki67 was demonstrated by Western blot and immunohistochemistry staining, and the tumor-specific cytotoxicity was assessed by crystal violet staining and cell viability assays. The G250-Ki67 and G250-ZD55-Ki67 adenoviruses could express E1A protein in 786-O and OSRC cell lines but not in ACHN and HK-2 cell lines. The expression of Ki67 gene in 786-O and OSRC cell lines were suppressed by these adenoviruses. The cytotoxic effects induced by G250-ZD55-Ki67 and G250-Ki67 were more obvious on the 786-O cell lines than on the OSRC cell lines. Each group of adenoviruses could inhibit the proliferation of the 786-O cells and OSRC cells. However, the effects induced by G250-ZD55-Ki67 and G250-Ki67 on 786-O cells were stronger than on OSRC cells. Moreover, G250-ZD55-Ki67 had enhanced antitumor activities in these renal cancer cells compared with G250-Ki67. G250 promoter-derived CRAds carrying Ki67-siRNA could highly amplify and express Ki67-siRNA in renal cancer cells with expression of G250 antigen, inhibit renal cancer cells proliferation and induce apoptosis. These results demonstrated that the G250-specific oncolytic adenovirus expressing Ki67-siRNA is applicable for human renal clear cell cancer therapy.