Objective:To investigate the effects of carcinoma-associated fibroblasts(CAFs)on chemoresistance of epithelial cancer cells and the underlying mechanism. Methods:Epithelial ovarian cancer cell Ovcar3 were exposed to cis-diammin-odichloroplatinum(DDP) with various concentrations and different duration,then CAFs cultured with Ovcar3 cell. The apoptosis of Ovcar3 cell was assessed by flow cytometry. The mRNA level of PI3K/AKT/XIAP was detected by real-time PCR. The protein level of PI3K,XIAP,AKT and AKT phosphorylation(p-AKT)was detected by Western blot. Signaling transduction inhibitors,LY294002 was used to block PI3K/AKT signaling pathways. Results:After co-culture,CAFs prevent DDP-induced apoptosis by upregulating the mRNA level and protein levels of PI3K/XIAP(P<0.05). In addition,p-AKT was enhanced by CAFs. Remarkably,inhibition of p-AKT by LY294002 can block the effects on DDP-induced XIAP up-regulation. Conclusion:These results demonstrate a novel mechanism by which CAFs regulates apoptosis and the possible involvement of the PI3K/AKT/XIAP survival pathway in chemoresistance of epithelial ovarian cancer cells.