Preliminary results of interferon- α therapy on woodchuck hepatitis virus-induced hepatocarcinogenesis: possible benefit in female transgenic mice

Background : C- myc activation is a potent oncogenic event in hepatocarcinogenesis. The aim of this study was to test the preventive effect of interferon- α (IFN- α) on the development of dysplasia and subsequent hepatocellular carcinoma (HCC) in transgenic (Tg) mice overexpressing c- myc in the liver. Methods : The WHV/c- myc Tg mice recapitulating woodchuck hepatitis virus-induced hepatocarcinogenesis were treated with IFN- α, starting early in life until sacrifice at pre-neoplastic or neoplastic stages. Transgene expression was assessed by reverse transcription-polymerase chain reaction (RT-PCR), hepatocyte proliferation was assessed by bromodeoxyuridine incorporation and RT-PCR for proliferating cell nuclear antigen, and apoptosis was assessed by in situ nick-end-labeling of DNA. Results : C- myc expression and hepatocyte proliferation were significantly reduced in treated female mice, without modification of apoptosis, correlating with a lower severity of dysplasia in 9/12 treated animals at pre-neoplastic stages. At the neoplastic stage, 2/3 treated females neither exhibited carcinoma nor dysplasia, while all 6/6 untreated mice and 3/3 treated males developed carcinomas. Conclusions : Inhibition of c- myc and hepatocyte proliferation by long-term administration of IFN- α was associated with a decrease, or a delay, of oncogenesis in the mouse Tg HCC model. Whether c- myc and hepatocyte proliferation down-regulation could be relevant parameters of IFN- α efficiency for hepatocarcinogenesis prevention in cirrhotic patients should be established.