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

AIM:To investigate the molecular mechanism of alpha-fetoprotein (AFP) on regulating the proliferation of humanhepatocellular carcinoma cells.METHODS:Alpha-fetoprotein purified from human umbilicalblood was added to cultured human hepatocellular carcinomaBel 7402 cells in vitro for various treatment periods.Theexpression of c-fos,c-jun,and N-ras mRNA involved inproliferation and differentiation of cells was analyzed byNorthern blot,and the expression of mutative p53 and p21rasproteins was determined by Western blot.RESULTS:The results showed that AFP (20 mg/L) stimulatedmRNA expression of these oncogenes in Bel 7402 cells.Theexpression of c-fos mRNA increased by 51.1%,60.9%,96.0%,and 25.5% at 2,6,12,and 24 h,respectively.Theexpression of c-junand N-ras mRNA reached to the maximumwhich increased by 81.3% and 59.9% as compared withthe control after 6 h and 24 h incubation with AFP,respectively.Western blot assay also demonstrated that AFP promotedthe expression of mutative p53 and p21rasproteins,and theincreased rate of those proteins was 13.0%,39.9%,and70.9%,as well as 35.2%,102.6%,and 46.8% at 6,12,and24 h,respectively,as compared with the control.Both humanserum albumin (the same dosage as AFP) and monoclonalanti-AFP antibody failed to stimulate the expression of theseoncogenes,but anti-AFP antibody could block the functionsof AFP.CONCLUSION:The data indicate that AFP can stimulate theexpression of some oncogenes to enhance the proliferationof human hepatocellular carcinoma Bel 7402 cells.