| Histone Deacetylase(HDACs)inhibitors can inhibit the proliferation of human tumor cells in culture by inducing cell cycle arrest,differentiation,and apoptosis.These agents are currently undergoing clinical trials evaluation.The researches have demonstrated that HDACs are associated with Multidrug Resistance(MDR)in tumor cells.MDR describes the phenomenon of cross-resistance to other structurally and functionally unrelated chemotherapy drugs.MDR represents a major impediment to successful cancer chemotherapy.TSA is a member of the hydroxamic acid of HDACs inhibitors.It plays an important role in the process of tumor progress.However,it is still unclear how TSA affects MDR in tumor cells.ObjectivesFirstly,to investigate the effects of histone deacetylase inhibitor(Trichostatin A,TSA)on the cell viability of MCF7 and human breast cancer doxorubicin-resistant MCF7/DOX cells.Secondly,to explore the effects of TSA on the apoptosis of MCF7 and human breast cancer doxorubicin-resistant MCF7/DOX cells.Thirdly,to investigate the expressions of apoptosis protein in MCF7 and MCF7/DOX cells.Finally,to investigate the molecular mechanisms of TSA on the sensitivity of multidrug resistance cells.MethodsTo investigate the effects of histone deacetylase inhibitor(Trichostatin A,TSA)on the cell viability of MCF7 and human breast cancer doxorubicin-resistant MCF7/DOX cells by MTT.To explore the effects of TSA on the apoptosis of MCF7 and human breast cancer doxorubicin-resistant MCF7/DOX cells by DNA ladder.To investigate the expressions of apoptosis protein expression in MCF7 and MCF7/DOX cells by Western blot.Finally,to discuss the related molecular mechanisms of TSA on the sensitivity of multidrug resistance cells through Western blot and fluorescence quantitative Real-time PCR.ResultsThe effects of TSA on MCF-7 and the survival rate of MCF-7/DOX cells were determined by the MTT.The results showed that the survival rates in MCF7 group were significantly higher than that in MCF7/DOX group under the 20 nM-200nM TSA,especially under 50 nM and 100 nM TSA.The survival rates were 0.95 and 0.65 in MCF7 group,while others were 0.55 and 0.40 in MCF7/DOX group.The results showed that comparing with MCF7 group,the DNA ladder strap was significantly increased in the MCF7/DOX group,which exposed to 50 nM and 100 nM TSA by agarose gel electrophoresis.And TSA induced apoptosis of MCF7/DOX cells is more significant than the MCF7 group.While the apoptosis phenomenon demonstrated in the 50 nM TSA in the MCF7/DOX group was without he MCF7 group.The protein of PARP and Caspase 6 were extracted from MCF7 and MCF7/DOX exposed to 0nM,50nM and 100nM TSA after 24h.The results showed that the protein expression level of PARP and Caspase 6 were significantly higher than that in MCF7 group.The protein expression level of acetylated H4 and H3 were detected by Western blot in the MCF7 and MCF7/DOX cells.The results showed that there was no significant difference between two protein expressions in two cell lines.The mRNA expressions level of acetylated H4 and H3 were detected by Real-time fluorescence quantitative PCR in the MCF7 and MCF7/DOX cells.The results showed that there was no significant difference between two mRNA expressions in the two cell lines.ConclusionsHistone deacetylase inhibitor TSA inhibits cell proliferation through activation of Caspase 6.TSA was more sensitive to MCF7/DOX comparing with MCF7.However,the reason is not the different expression between the acetylation of H3 and H4.TSA has the potential to be applied in the treatment of multidrug resistance. |
