TMET-12. TARGETING AMINO ACID METABOLIC VULNERABILITIES IN GLIOMAS

Abstract Isocitrate dehydrogenase (IDH) wild-type gliomas and IDH mutant gliomas are similar in histologic appearance but differ in their genetic and metabolic backgrounds. This study aimed to reveal the difference in metabolites between IDH-wildtype glioma and IDH-mutant glioma, and to find the effective treatment according to the status of IDH in gliomas. Two artificial cell lines made from human astrocyte were used: NHAE6E7hTERTRas (IDH-wildtype) and NHAE6E7hTERTIDHmut (IDH-mutant). Using capillary electrophoresis- and ion chromatography–coupled mass spectrometry, the amount of asparagine was lower in NHAE6E7hTERTRas cells compared with NHAE6E7hTERTIDHmut cells, whereas the amount of glutamine, glutamate and 2-oxoglutarate in NHAE6E7hTERTIDHmut cells was lower than NHAE6E7hTERTRas cells. L-asparaginase, which converts asparagine into aspartate, was more effective in NHAE6E7hTERTRas cells than NHAE6E7hTERTIDHmut cells. L-asparaginase induced autophagy and inhibition of autophagy by 3-MA suppressed L-asparaginase-induced antitumor effect, which meant that the antitumor effect was at least partially due to the L-asparaginase-induced autophagy. Pharmacological or genetical inhibition of GLUD1 which converts glutamate to 2-oxoglutarate, suppressed proliferation of the cells by inducing ROS and apoptosis in NHAE6E7hTERTIDHmut cells. ROS inhibitor, NAC suppressed GLUD1 inhibitor-induced ROS, apoptosis, and cytotoxicity in NHAE6E7hTERTIDHmut cells, revealing that cytotoxicity by GLUD1 inhibitor was at least partially due to the inhibitor-induced ROS. The experiments using mutant IDH1 overexpressed glioma cell line showed similar sensitivity to GLUD1 inhibitor to NHAE6E7hTERTIDHmut, which suggested that the difference of sensitivity to GLUD1 inhibitor was due to the status of mutant IDH. In vivo experiments, L-asparaginase suppressed the growth of xenografted glioma cells without mutant IDH, whereas GLUD1 inhibitor inhibited the proliferation of xenografted glioma cells with overexpressed mutant IDH1. In conclusion, L-asparaginase and Glud1 inhibitor will be new therapeutic option for IDH-wildtype glioma and IDH-mutant glioma, respectively.