PP242Enhances Chemosensitivity Of Ovarian Cancer Cell Lines And Mechanism Research

Objective: To investigate the effect of the mammalian target of rapamycin (mTOR)Inhibitor III,PP242,combined with Taxol in human ovarian cancer cell lines A2780andSKOV3and explore the potential molecular mechanisms.Methods: A2780and SKOV3cells were treated with various concentration of taxol,cellproliferation inhibition rate was measured by methyl thiazolyl tetrazolium(MTT) assay andcell apoptosis condition was assessed by flow cytometry.The expression conditions ofmTOR and its downstream molecule in A2780and SKOV3cells was analyzed by westernblot after treatment of TOR Inhibitor PP242. A2780and SKOV3cells were treated withPP242combined Taxol,cell apoptosis was monitored by flow cytometry and Hoechst33342staining.The changes of cytoplasmic microtubular stucture were detected by immuno-fluorescent dyeing.Results: Apoptosis rate was elevated in A2780and SKOV3cells with increasedconcentration of Taxol and prolonged time,however, it was not obvious for24hours andthere was no significant difference between48hours and72hours in SKOV3cells.Theprotein expression levels of phosphorylated mTOR, phosphorylated p70S6kinase(S6K)1and Survivin in A2780and SKOV3cells were decreased after treatment of PP242for24hours.Apoptosis rate was markedly increased when the cells were treated with PP242combined Taxol,especially for48hours its reached to the peak.Cell nuclear condensationand fragmentation were obviously showed by Hoechst33342nuclear staining and thechanges of tubulin distribution in cytoplasm were distinctly visualized by immuno-fluorescent dyeing.Conclusion: mTOR Inhibitor III-PP242significantly increased the chemosensitivity ofovarian cancer cell lines A2780and SKOV3to Taxol by down-regulation of p-mTOR、p-S6K1and Survivin. Objective: By examining the expression of Signal transducer and activator oftranscription3(Stat3) in ovarian carcinoma cisplatin-sensitive cell line OV2008and cisplatin-resistance cell line C13K,this study was to investigate the effect of small moleculeStat3inhibitor Stattic in OV2008and C13K cells to cisplatin and explore the potentialmolecular mechanisms.Methods: The expression level of Stat3mRNA and phosphorylated Stat3(p-Stat3) proteinin OV2008and C13K cells were detected by semi-quantitative reversetranscription-polymerase chain reaction(RT-PCR) and western blot. The effect of cellProliferation to cisplatin alone was measured by methyl thiazolyl tetrazolium(MTT) assay.Cell apoptosis rate was analyzed by flow cytometry and protein expression ofphosphorylated Stat3(p-Stat3)、phosphorylated Akt(p-Akt) and anti-apoptosis factor Bcl-XLwere monitored after treatment with cisplatin and/or Stat3inhibitor.Results: Compared with those in OV2008cells,Stat3mRNA and p-Stat3protein were bothover-expressed in C13K cells. The inactivation of Stat3by small molecule inhibitorStattic lead to the increases of apoptosis rate both in OV2008cells and C13K cells tocisplatin.When treated with Stattic combined cisplatin,the expression of p-Stat3、p-Akt andBcl-XL had a distinct decline.Conclusion:Small molecule Stat3inhibitor Stattic played an effect role in drug sensitivityto cisplatin in cisplatin-resistance cell line C13K,which was possibly relevant to thedown-regulation of anti-apoptosis factor Bcl-XL.Stat3will be a promising targeted factorfor the drug resistance of ovarian carcinoma.