MG132 Induced Apoptosis Of HepG2 Cells And Its Effect On MDR Expression

Aim The study was undertaken to investigate the effects of MG132 on UPPand MDR expression, and we explore the mechanism of HepG2 cell apoptosis induced by MG132.Methods HepG2 cell apoptosis was determined by flow cytometryanalysis,Hoechst 33258 and Acridine orange staining. RT-PCR was used to detect the levels of E1,E2,E3,26S proteasome,p53,Caspase3,MDR mRNA. Immunohistochemistry was used to detect p53,Caspase3,P-gp protein expression. Western Blot was performed to detect P-gp expression. Intracellular EPI concentration was detected by HPLC.Results After 24 hours treatment with 2 μ mol/L,5 μ mol/L MG132respectively, apoptotic rate was increased with typical morphological features of apoptosis such as nuclear condensation and fragmentation in HepG2 cells. MG132 up-regulated p53,Caspase3 mRNA and protein expression, whereas E1,E2,E3,26S proteasome mRNA levels were down-regulated. The data of FCA and AO staining indicated that the cytotoxicity of 1 μ g/ml EPI to HepG2 cells was enhanced by 1 μ mol/L MG132, and similar effect was obtained as using 2μg/ml EPI separately. MG132 attenuated MDR mRNA and P-gp expression. Compared with EPI group, intracellular EPI concentration was increased by applying relatively low dose EPI and MG132 together.