ObjectiveThe development of multidrug resistance (MDR) remains the significant clinical challenge in ovarian cancer therapy; however, relatively little is known about how to prevent the emergence of MDR during chemotherapy treatment. NSC23925 previously has been shown to prevent the development of MDR in osteosarcoma cells in vitro. The purpose of this study was to evaluate the effects of NSC23925 on the prevention of MDR in ovarian cancer, especially in vivo. MethodsHuman ovarian cancer cells were treated with paclitaxel alone or in combination with NSC23925 in vitro and in vivo. MDR ovarian cancer cells were established both in cultured cells and mouse models. The expression levels of Pgp and MDR1 were evaluated in various selected cell sublines by Western blot and real-time PCR. Pgp activity was also determined. ResultsPaclitaxel treated cells eventually developed MDR with overexpression of Pgp and MDR1, and with high activity of Pgp, while paclitaxel–NSC23925 co-treated cells remained sensitive to chemotherapeutic agents in both in vitro and in vivo models. There was no observed increase in expression level and activity of Pgp in paclitaxel–NSC23925 co-treated cells. Additionally, there were no changes in the sensitivity to chemotherapeutic agents, nor expression of Pgp, in cells cultured with NSC23925. ConclusionOur findings suggest that NSC23925 can prevent the emergence of MDR in ovarian cancer both in vitro and in vivo. The clinical use of NSC2395 at the onset of chemotherapy may prevent the development of MDR and improve the clinical outcome of patients with ovarian cancer.