Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are frequently found in several human cancer types including acute myeloid leukemia (AML) and lead to the production of high levels of the oncometabolite (R)-2-hydroxyglutarate (R-2HG). Here we report the characterization of BAY1436032, a novel pan-mutant IDH1 inhibitor, both in vitro and in vivo. BAY1436032 specifically inhibits R-2HG production and colony growth, and induces myeloid differentiation of AML cells carrying IDH1R132H, IDH1R132C, IDH1R132G, IDH1R132L and IDH1R132S mutations. In addition, the compound impacts on DNA methylation and attenuates histone hypermethylation. Oral administration of BAY1436032 led to leukemic blast clearance, myeloid differentiation, depletion of leukemic stem cells and prolonged survival in two independent patient-derived xenograft IDH1 mutant AML mouse models. Together, BAY1436032 is highly effective against all major types of IDH1 mutant AML.

Intracellular signaling governed by serine/threonine kinases comprises the molecular interface between cell surface receptors and the nuclear transcriptional machinery. The protein kinase C (PKC) family members are involved in the control of many signaling processes directing cell proliferation, motility, and survival. Here, we examined a role of different PKC isoenzymes in protein phosphatase 2A (PP2A) and HRSL3 tumor suppressordependent cell death induction in the ovarian carcinoma cell line OVCAR-3. Phosphorylation and activity of PKC isoenzymes were measured in response to PP2A or phosphoinositide 3-kinase inhibition or HRSL3 overexpression. These experiments indicated a regulation of PKCθ, ε, ζ, and ι through PP2A and/or HRSL3, but not of PKCα and β. Using isoform-specific peptide inhibitors and overexpression approaches, we verified a contribution to PP2A-and HRLS3-dependent apoptosis only for PKCζ, suggesting a proapoptotic function of this kinase. We observed a significant proportion of human ovarian carcinomas expressing high levels of PKCζ, which correlated with poor prognosis. Primary ovarian carcinoma cells isolated from patients also responded to okadaic acid treatment with increased phosphorylation of PKCζ and apoptosis induction. Thus, our data indicate a contribution of PKCζ in survival control in ovarian carcinoma cells and suggest that upregulation or activation of tyrosine kinase receptors in this tumor might impinge onto apoptosis control through the negative regulation of the atypical PKCζ. Mol Cancer Res; 8(6); 919-34. ©2010 AACR.

Key Words: peroxisome proliferator-activated receptor Ⅲ atherosclerosis Ⅲ diabetes mellitus Ⅲ vascular biology T he peroxisome proliferator-activated receptor ␥ (PPAR␥) belongs to the nuclear receptor family of ligand-dependent transcription factors. 1 PPAR␥ plays an important role in glucose homeostasis and is pharmacologically targeted by the class of insulin-sensitizing drugs named thiazolidinediones or glitazones. 1,2 In addition to its critical metabolic function, glitazone-activated PPAR␥ exhibits potent anti-inflammatory and vascular protective effects by directly affecting gene expression in monocytes/macrophages, T lymphocytes, endothelial cells, and vascular smooth muscle cells (VSMCs). 3,4 PPAR␥-mediated gene regulation comprises several distinct mechanisms, including ligand-dependent transactivation, ligand-independent repression, and ligand-dependent transrepression. 4 For its anti-inflammatory actions in macrophages, inhibition of gene expression by ligand-dependent transrepression has been identified as a key molecular process. 5 However, the molecular mechanisms underlying Original received July 26, 2011; revision received December 14, 2011; accepted December 16, 2011. In November 2011, the average time from submission to first decision for all original research papers submitted to Circulation Research was 15 days.From the Center for Cardiovascular Research, Institute of Pharmacology, Campus Charité Mitte (M.B., V.B., I.N.B., L.H., H.W., K.K., T.U., A.F.-L., U.K.), and Department of Endocrinology, Diabetes, and Nutrition (J.S.), Charité Universitätsmedizin Berlin, Berlin, Germany; Department of Cardiology, Giessen University (A.P., D.S.), Giessen, Germany; Department of Clinical and Experimental Medicine G. Salvatore, University of Catanzaro Magna Graecia (F.P., A.B.), Catanzaro, Italy; German Heart Institute Berlin, Department of Cardiology (P.S.), Berlin, Germany; and Instituto di Endocrinologia ed Oncologia Sperimentale del CNR Gaetano Salvatore, Università di Napoli Federico II (A.F.), Napoli, Italy.* Matrix metalloproteinase-9 (MMP-9) and endothelin-1 (ET-1) are PPAR␥ target genes in vascular cells involved in the development of atherosclerosis and have been characterized as important mediators of the vascular protective actions of PPAR␥. 6 -8 PPAR␥ activation by glitazones results in marked inhibition of MMP-9 mRNA/protein expression and its gelatinolytic activity in VSMCs, which indicates MMP-9 as a potential candidate gene for ligand-dependent transrepression in these cells. 8 High-mobility group (HMG) proteins are chromatinbinding proteins that consist of the 3 family members HMGA, HMGB, and HMGN. 9 HMG proteins act as architectural elements that affect various DNA-dependent processes in the context of chromatin. 9 Via DNA-protein or protein-protein interactions, HMG proteins regulate gene transcription and influence multiple biological processes, including cell growth, proliferation, differentiation, and death. 9 The present study aimed to characterize the molecular process of ligand-de...