IDH1 p.R132 mutations may not be actively involved in the carcinogenesis of hepatocellular carcinoma

Recent studies have identified prevalent isocitrate dehydrogenase 1 (IDH1) codon 132 mutations (p.R132) in gliomas and acute myeloid leukemia (AML). The IDH1 mutations lead to a loss of its normal enzymatic activity and acquisition of neomorphic activity in production of alpha-ketoglutarate (alpha-KG) and 2-hydroxyglutarate (2-HG), which finally cause alterations of multiple gene expression of tumorigenesis-associated alpha-KG-dependent enzymes. The aim of this study was to determine whether IDH1 p.R132 mutations are involved in the carcinogenesis of hepatocellular carcinoma

A total of 87 Han Chinese patients with primary hepatocellular carcinoma (HCC) were analyzed by direct DNA sequencing for IDH1 p.R132 mutations. The expression levels of multiple alpha-KG-dependent enzymes and associated genes were quantified in HepG2 cells overexpressing IDH1 p.R132 mutants by Western blotting and real-time PCR.

None of 87 Han Chinese patients with HCC harbored any IDH1 p.R132 mutations. The protein levels of HIF-1alpha and histone methylation marker (H3K4me3 and H3K79me2) were determined in HepG2 cells overexpressing IDH1 p.R132 mutants, but we discerned no difference. Measurement of mRNA expression levels of VEGF, GLUT1, and HOXA genes also showed no significant difference between cells overexpressing IDH1 wild-type and p.R132 mutants.

Our negative results, together with some previous reports of the absence of IDH1 p.R132 mutations in HCC tissues, suggests that IDH1 p.R132 mutations are not actively involved in the development of HCC.