The histone H3 lysine 27 (H3K27) methyltransferase EZH2 plays an important role in regulating gene expression, and its aberrant activity is linked to the onset and progression of cancer. GSK126 is a selective, S-adenosyl-methionine-competitive small molecule inhibitor of EZH2 methyltransferase activity (Ki = 0.57 nM; IC50 = 9.9 nM versus that of EZH1: Ki = 89 nM; IC50 = 680 nM). It is more than 1,000-fold selective for EZH2 over other histone methyltranferases, including both SET-domain-containing and non-SET-domain-containing methyltransferases. At concentrations of 7-252 nM, it has been shown to inhibit global H3K27 trimethylation levels and to reactivate silenced PRC2 target genes. Furthermore, GSK126 can inhibit the proliferation of EZH2 mutant DLBCL cell lines (IC50 = 28-61 nM) as well as the growth of EZH2 mutant DLBCL xenografts in mice receiving a daily dose of 50 mg/kg.
