[Construction and study of replication-defective adenovirus targeting hepatocarcinoma].

Background & Objective: Antioncogene p16 is one of the most important genes used in tumor gene therapy. Apoptosis induced by adenovirus mediated overexpression of p16 in cancer cells has been confirmed in various p16 gene inactive cancers. Studies have indicated that p16 gene is frequently inactive in human primary hepatocarcinoma. Therefore this study was to investigate the effect of exogenous p16 gene driven by alpha fetoprotein (AFP) core promoter on human hepatocellular carcinoma cells and further explore the potentials of p16 in hepatocellular carcinoma gene therapy.

Methods: The recombinant replication-defective adenovirus Ad-AFP-p16 containing p16 gene downstream the AFP core promoter-AF0.3 was constructed and infected hepatocellular carcinoma cells. The expression of p16 was detected by Western blot. The effects of exogenous p16 gene on cell growth and apoptosis were measured by MTT, flow cytometry and DNA ladder in vitro. Subcutaneous injection of mouse hepatocarcinoma cell line H22 infected with Ad-AFP-p16 was applied to observe the effect of Ad-AFP-p16 on tumorigenesis in vivo.

Results: Over-expression of exogenous p16 gene was confirmed in hepatocarcinoma cells infected with Ad-AFP-p16. Cell growth was inhibited by (94.42+/-11.70)% and (94.99+/-6.74)% in Be1-7402 and HepG2 cells on the 6th day after virus infection; 39.57% and 39.75% apoptotic cells were also induced respectively in these two cell lines on the 2nd day. Moreover, the infection of Ad-AFP-p16 significantly inhibited the tumorigenesis of mouse hepatocarcinoma cell line H22 in vivo. The tumor volumes of control, Ad-GFP, Ad-AFP-p16 and Ad-CMV-p16 groups were (1.54+/-0.65)cm(3), (1.71+/-1.01)cm(3), (0.25+/-0.39)cm(3) and (0.25+/-0.45)cm(3), respectively.

Conclusion: The expression of p16 gene driven by AFP promoter can induce apoptosis in hepatocarcinoma cells.