Elhammali Adnan, Ippolito Joseph E, Collins Lynne, Crowley Jan, Marasa Jayne, Piwnica-Worms David
Authors' Affiliations:BRIGHT Institute, Molecular Imaging Center, Mallinckrodt Institute of Radiology;
Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri; and.
Cancer Discov. 2014 Jul;4(7):828-39. doi: 10.1158/2159-8290.CD-13-0572. Epub 2014 Apr 16.
Recently identified isocitrate dehydrogenase (IDH) mutations lead to the production of 2-hydroxyglutarate (2HG), an oncometabolite aberrantly elevated in selected cancers. We developed a facile and inexpensive fluorimetric microplate assay for the quantitation of 2HG and performed an unbiased small-molecule screen in live cells to identify compounds capable of perturbing 2HG production. Zaprinast, a phosphodiesterase 5 inhibitor, was identified as an efficacious modulator of 2HG production and confirmed to lower 2HG levels in vivo. The mechanism of action was not due to cGMP stabilization, but rather, profiling of metabolites upstream of mutant IDH1 pointed to targeted inhibition of the enzyme glutaminase (GLS). Zaprinast treatment reversed histone hypermethylation and soft-agar growth of IDH1-mutant cells, and treatment of glutamine-addicted pancreatic cancer cells reduced growth and sensitized cells to oxidative damage. Thus, Zaprinast is efficacious against glutamine metabolism and further establishes the therapeutic linkages between GLS and 2HG-mediated oncogenesis.
Gain-of-function IDH mutations are common events in glioma, acute myelogenous leukemia, and other cancer types, which lead to the accumulation of the oncometabolite 2HG. We show that the drug Zaprinast is capable of reducing cellular 2HG levels by inhibiting the upstream enzyme GLS, thus identifying a new strategy to target 2HG production in selected IDH-mutant cancers.
最近发现的异柠檬酸脱氢酶（IDH）突变会导致2-羟基戊二酸（2HG）的产生，2HG是一种在某些癌症中异常升高的致癌代谢物。我们开发了一种简便且低成本的荧光微孔板检测方法来定量2HG，并在活细胞中进行了无偏差的小分子筛选，以鉴定能够干扰2HG产生的化合物。磷酸二酯酶5抑制剂扎普司特被鉴定为2HG产生的有效调节剂，并在体内证实可降低2HG水平。其作用机制并非由于cGMP的稳定，而是对突变型IDH1上游代谢物的分析表明其靶向抑制了谷氨酰胺酶（GLS）。扎普司特处理可逆转IDH1突变细胞的组蛋白高甲基化和软琼脂生长，并且对谷氨酰胺成瘾的胰腺癌细胞的处理可降低其生长并使细胞对氧化损伤敏感。因此，扎普司特对谷氨酰胺代谢有效，并进一步确立了GLS与2HG介导的肿瘤发生之间的治疗联系。
功能获得性IDH突变在胶质瘤、急性髓性白血病和其他癌症类型中是常见事件，这会导致致癌代谢物2HG的积累。我们表明，药物扎普司特能够通过抑制上游酶GLS来降低细胞内2HG水平，从而确定了一种针对某些IDH突变癌症中2HG产生的新策略。
