Effects Of Proteasome Inhibitor MG-132 On The Proliferation And Apoptosis Of Human Colon Cancer HCT-116 Cell

Objective: To investigate the effect of proteasome inhibitor on cell proliferation and apoptosis of human colon cancer cell line HCT-116.also to explore its possible mechanisms of anti-cancer effects.Methods: In vitro, human colon cancer cell line HCT-116 was treated by proteasome inhibitor (MG-132) in different concentrations. by means of MTT assay, the absorbance value was detected and growth inhibition rate was calculated. Cell cycle and apoptosis were assessed by flow cytometry (FCM);The changes of cell morphology were observed by inverted and confocal microcope. The mRNA expressions of bcl-2,p27,caspase-3 were analyzed by reverse transcriplase polymerase chain reaction (RT-PCR). Western Blot was used to detect bcl-2,p27,caspase-3 protein expression.Results: (1) MTT assay indicated that the inhibitory effect of MG-132 on the proliferation of HCT-116 cell was found in dose-and-time dependent manner. There was great statistical signification between varies medicated group and control group (P<0.05), and there also were great statistical signification between medicated group each other (P<0.05). (2) Flow cytometry showed that the HCT-116 cell cycle was induced by MG-132 at 48 hours, the ratio of G0/G1 phase was increased and the ratio of S phase was decreased, in dose-dependent manner (P<0.05). (3)RT-PCR assay showed that the expression of p27 and caspase-3 mRNA were up-regulated and bcl-2 mRNA was down-regulated by MG-132 at 48 hours with concentration incread (P<0.05).(4)Immunocytochemistry showed that the expression of p27 and caspase-3 protein were up-regulated and bcl-2 protein was down-regulated with concentration incread(P<0.05).Conclusion: the growth of HCT-116 cell in vitro was inhibited by MG-132 and in dose-and-time dependent maner. it could also induce HCT-116 cell apoptosis and arrest cell cycle at the phase of G0/G1, induce cell apoptosis. May be its mechanism was through upregulating expressions of p27,caspase-3 mRNA and protein, downregulating the expression of bcl-2 mRNA and protein.