The oncometabolite D-2-hydroxyglutarate induced by mutant IDH1 or -2 blocks osteoblast differentiation in vitro and in vivo

// Johnny Suijker 1 , Hans J. Baelde 1 , Helene Roelofs 2 , Anne-Marie Cleton-Jansen 1 , Judith V.M.G. Bovée 1 1 Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands 2 Department of Immuno-Haematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands Correspondence to: JVMG Bovée, e-mail: j.v.m.g.bovee@lumc.nl Keywords: isocitrate dehydrogenase, enchondroma, mesenchymal stem cells, ollier disease, maffucci syndrome Received: March 24, 2015 Accepted: May 13, 2015 Published: May 25, 2015 ABSTRACT Mutations in isocitrate dehydrogenase 1 ( IDH1 ) and IDH2 are found in a somatic mosaic fashion in patients with multiple enchondromas. Enchondromas are benign cartilaginous tumors arising in the medulla of bone. The mutant IDH1/2 causes elevated levels of D-2-hydroxyglutarate (D-2-HG). Mesenchymal stem cells (MSC) are the precursor of the osteoblastic, chondrogenic and adipocytic lineage and we hypothesized that increased levels of D-2-HG cause multiple enchondromas by affecting differentiation of MSCs. Bone marrow derived MSCs from different donors were differentiated towards osteoblastic, chondrogenic and adipocytic lineage in the presence or absence of 5 mM D-2-HG. Three of four MSCs showed near complete inhibition of calcification after 3 weeks under osteogenic differentiation conditions in the presence of D-2-HG, indicating a block in osteogenic differentiation. Two of four MSCs showed an increase in differentiation towards the chondrogenic lineage. To evaluate the effect of D-2-HG in vivo we monitored bone development in zebrafish, which revealed an impaired development of vertebrate rings in the presence of D-2-HG compared to control conditions ( p -value < 0.0001). Our data indicate that increased levels of D-2-HG promote chondrogenic over osteogenic differentiation. Thus, mutations in IDH1/2 lead to a local block in osteogenic differentiation during skeletogenesis causing the development of benign cartilaginous tumors.