Inhibition of hTERT gene in human hepatocellular carcinoma Bel-7402 cells by conditionally replicative adenovirus leads to inhibition of proliferation and induction of apoptosis

Objective To evaluate the effects of suppressing hTERT gene expression on the cell proliferation and apoptosis of human hepatocellular carcinoma Bel-7402 cells with ZD-hTERT, an E1B-55KD gene-deleted conditionally replicative adenovirus armed with small interference RNA targeting hTERT gene. Methods Hepatocellular carcinoma Bel-7402 cells were infected with ZD-hTERT, ZD55-EGFP,an El B-55kd gene-deleted conditionally replicative adenovirus, Ad-hTERT, a replication-deficient adenovirus espressing hTERT-siRNA and Ad-EGFP, a replication-deficient adenovirus, respectively. El A protein expression was determined by Western blot. The hTERT expression levels of Bel-7402 cells were detected by RT-PCR and Western blot analysis respectively. Cell prohferation was assayed by MTr meth-ed. Bel-7402 cells were stained with crystal violet to assay tumor-selective eytotoxieity. Cell apoptosis was measured by TUNEL assay. Results Western blot assay of ElA expression indicated Bel-7402 cells in-fected with ZD-hTERT and ZD-EGFP could express ElA, but the cells infected with Ad-hTERT and Ad-EGFP could not. Significant reductions of hTERT mRNA and protein content were observed in lysates from Bel-7402 ceils infected with ZD-hTERT. Crystal violet stain and MTT assay demonstrated that the antitu-mot effect of ZD-hTERT was more potent than both ZD-EGFP and Ad-hTERT. ZD-hTERT treatment of Bel-7402 cells resulted in an increase of apoptotie cells as compared with ZD-EGFP and Ad-hTERT treat-ment. Conclusion ZD-hTERT can replicate selectively in Bel-7402 cells and result in cancer-specific cy-totoxicity. Conditionally replicative adenovirus armed with aiRNA against hTERT gene may prove to be a useful novel tool for renal cancer therapy. Key words: Adenovirus;  hTERT gene;  RNA interference;  Carcinoma,hepatoeellular