Alpha-fetoprotein stimulated the expression of some oncogenes in human hepatocellular carcinoma Bel 7402 cells.

Abstract

To investigate the molecular mechanism of alpha-fetoprotein (AFP) on regulating the proliferation of human hepatocellular carcinoma cells. Alpha-fetoprotein purified from human umbilical blood was added to cultured human hepatocellular carcinoma Bel 7402 cells in vitro for various treatment periods. The expression of c-fos, c-jun, and N-ras mRNA involved in proliferation and differentiation of cells was analyzed by Northern blot, and the expression of mutative p53 and p21(ras) proteins was determined by Western blot. The results showed that AFP (20 mg/L) stimulated mRNA expression of these oncogenes in Bel 7402 cells. The expression of c-fos mRNA increased by 51.1%, 60.9%, 96.0%, and 25.5% at 2, 6, 12, and 24 h, respectively. The expression of c-jun and N-ras mRNA reached to the maximum which increased by 81.3% and 59.9% as compared with the control after 6 h and 24 h incubation with AFP, respectively. Western blot assay also demonstrated that AFP promoted the expression of mutative p53 and p21(ras) proteins, and the increased rate of those proteins was 13.0%, 39.9%, and 70.9%, as well as 35.2%, 102.6%, and 46.8% at 6, 12, and 24 h, respectively, as compared with the control. Both human serum albumin (the same dosage as AFP) and monoclonal anti-AFP antibody failed to stimulate the expression of these oncogenes, but anti-AFP antibody could block the functions of AFP. The data indicate that AFP can stimulate the expression of some oncogenes to enhance the proliferation of human hepatocellular carcinoma Bel 7402 cells.