Expression of p53 in the apoptosis of human hepatocelluar cancer cell line HepG_2 induced by proteasome inhibitor MG132

Objective To study the effect on expression of p53 in the apoptosis of human hepatocelluar cancer cells(HepG2) induced by proteasome inhibitor MG132 . Methods HepG2 cells were treated with MG132 (2,5,10 μmol/L) for 24 hours. The apoptotic cells were determined by flow cytometric analysis and Hoechst 33258 fluorescence staining. p53 protein expression was detected by immunohistochemistry. Results The results showed that the increase of the degree of HepG2 cell apoptosis was concentration-dependent. Marked morphological changes of cell apoptosis including chromosome condensation and nuclear fragmentation were observed very clearly by Hoechst 33258 fluorescence staining especially after the cells treated with MG132 for 24 h.Immunohistochemistry showed that p53 protein expression was increased in treatment group. Conclusion Proteasome inhibitor MG132 could induce HepG2 cell apoptosis by inhibiting ubiquitin-proteasome pathway(UPP) activity , up-regulating the protein expression of p53.