17-AAG enhances the cytotoxicity of flavopiridol in mantle cell lymphoma via autophagy suppression.

Flavopiridol, a cyclin-dependent kinase inhibitor (CDKI), shows promising anti-tumor activity in hematologic malignancies. However, Flavopiridol-induced protective autophagy may lead to drug resistance. Here we found that Hsp90 inhibitor 17-AAG can sensitize mantle cell lymphoma (MCL) cells to flavopiridol by suppressing flavopiridol-triggered protective autophagy. The suppressing effect of 17-AAG on autophgy was mediated by Beclin1 degradation and ERK inactivation. Furthermore, 17-AAG enhanced flavopiridol-induced apoptosis and growth suppression in MCL cells. Our study may provide some insights into CDKI -targeted chemotherapies.