The Cdc2/Cdk1 inhibitor, purvalanol A, enhances the cytotoxic effects of taxol through Op18/stathmin in non-small cell lung cancer cells invitro.

Abstract

PurvalanolA is a highly selective inhibitor of Cdc2[also known as cyclin-dependent kinase1(CDK1)]. Taxol is an anti-tumor chemotherapeutic drug which is widely used clinically. In this study, the CDK1 inhibitor, purvalanolA was applied to explore the relevance of Cdc2 signaling and taxol sensitivity through analyses, such as cellular proliferation and apoptosis assays, ELISA, western blot analysis and immunoprecipitation. We demonstrated that purvalanolA effectively enhanced the taxol-induced apoptosis of NCI-H1299 cells, as well as its inhibitory effects on cellular proliferation and colony formation. In combination, purvalanolA and taxol mainly decreased the expression of oncoprotein18(Op18)/stathmin and phosphorylation at Ser16 andSer38, while purvalanolA alone inhibited the phosphorylation of Op18/stathmin at all 4serine sites. Co-treatment with purvalanolA and taxol weakened the expression of Bcl-2 and activated the extrinsic cell death pathway through the activation of caspase-3 and caspase-8. Further experiments indicated that Cdc2 kinase activities, including the expression of Cdc2 and the level of phospho-Cdc2(Thr161) were significantly higher in taxol-resistant NCI-H1299 cells compared with the relatively sensitive CNE1 cells before and following treatment with taxol. These findings suggest that Cdc2 is positively associatd with the development of taxol resistance. The Cdc2 inhibitor, purvalanolA, enhanced the cytotoxic effects of taxol through Op18/stathmin. Our findings may prove to be useful in clinical practice, as they may provide a treatment strategy with which to to reduce the doses of taxol applied clinically, thus alleviating the side-effects.