First-in-Class Dual EZH2-HSP90 Inhibitor Eliciting Striking Antiglioblastoma Activity In Vitroand In Vivo

Structural analysis of tazemetostat, an FDA-approved EZH2 inhibitor, led us to pinpoint a suitable site for appendage with a pharmacophoric fragment of second-generation HSP90 inhibitors. Resultantly, a magnificent dual EZH2/HSP90 inhibitor was pinpointed that exerted striking cell growth inhibitory efficacy against TMZ-resistant Glioblastoma (GBM) cell lines. Exhaustive explorations of chemical probe 7led to several revelations such as (i) compound 7increased apoptosis/necrosis-related gene expression, whereas decreased M phase/kinetochore/spindle-related gene expression as well as CENPs protein expression in Pt3R cells; (ii) dual inhibitor 7induced cell cycle arrest at the M phase; (iii) compound 7suppressed reactive oxygen species (ROS) catabolism pathway, causing the death of TMZ-resistant GBM cells; and (iv) compound 7elicited substantial in vivoanti-GBM efficacy in experimental mice xenografted with TMZ-resistant Pt3R cells. Collectively, the study results confirm the potential of dual EZH2-HSP90 inhibitor 7as a tractable anti-GBM agent.