Renal cell carcinoma with a novel germ-line mutation in isocitrate dehydrogenase 1 (IDH1) and its functional study.

Abstract

e15568 Background: Recently, omics study such as metabolome analysis and whole genome sequencing has been applied to various disorders. We predicted the dysfunction of isocitrate dehydrogenase 1 (IDH1) in renal cell carcinoma (RCC) using metabolome analysis and identified a novel mutation of IDH1. In addition, we examined its function. Methods: We determined the global-scale metabolome profiling of human RCC by capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS), and compared the metabolite levels of tumors and paired normal tissues in 10 patients with RCC. We performed the genotyping of IDH1 and von Hippel-Lindau (VHL) gene. We also performed transfection experiments by using Lipofectamine and measured the enzymatic activity of IDH1 in RCC cell lines. All protocols were performed by the Institutional Review Board (IRB) of Hamamatsu University School of Medicine and Keio University. Informed consent was obtained from the patient in accordance with the IRB of Hamamatsu University School of Medicine. Results: The acceleration of glycolysis with low level of NADPH and citrate in one patient led to IDH1 dysfunction followed by identifying a novel missense mutation, V178I. In transfection experiment, the reductive activity of IDH1 variant (V178I) increased 2.5 times than that of IDH1 wild type while the oxidative activity of IDH1 variant oxidative activity was as well as that of IDH1 wild type. Furthermore, in the metabolome analysis using labeling glutamine, RCC cell lines deficient in the von Hippel-Lindau (VHL) protein preferentially use reductive glutamine metabolism. On the other hand, this patient with V178I mutation of IDH1 had no VHL mutation. Conclusions: Metabolome analysis led to the identification a novel IDH1 missense mutation in RCC. This mutation might be involved with acceleration of reductive reaction in tricarboxylic acid cycle. Metabolome analysis using CE-TOFMS could be a powerful tool for the global-scale exploration of disease-specific metabolism.