Quantitative analysis of 2-hydroxyglutarate as a controversial oncometabolite in malignant gliomas

There is a great effort to connect the accumulation of 2-hydroxyglutarate (2-HG) oncometabolite with cellular onco-epigenetic status and subsequently predict the prognoses of glioma patients. In this observational study, the concentrations of D- and L- 2-HG were determined in 57 tumor tissue samples of glioma patients (n=57) WHO grade I through IV (astrocytoma, oligodendroglioma, secondary glioblastoma, and glioblastoma multiforme) in vitro. Also, genetic mutation status on isocitrate dehydrogenase 1 and 2 (IDH 1/2) was determined from these samples. The objective of this study was to confirm or to reject the hypothesis of the direct correlation of 2-HG concentration in tumor tissue and the results from IDH 1/IDH 2 point mutation analyses. The concentrations of 2-HG were quantified using high sensitive HPLC and Q-TOF HRMS spectrometer setup. Concurrently, the genetic mutation analyses of both IDH 1 (cytosolic) and IDH 2 (mitochondrial) were performed by the isolation of tumor tissue DNA, PCR amplification, and subsequent Sanger forward sequencing. Our results indicate that there is no definite correlation between the two as we identified cases of glioma tumors with significantly increased concentration of one or both L- and D- 2-HG but no IDH 1/2 mutations (44% 2-HG positive cases).