DDDR-18. COMPREHENSIVE PROTEOMIC PROFILING OF BRAFV600E GLIOMA CELLS SHOWS UPREGULATION OF GLYCOLYSIS AND TCA CYCLE PROTEINS AFTER COMBINED MTOR AND MAP KINASE PATHWAY BLOCKADE

Abstract

Abstract Low-grade gliomas (LGG) are slow-growing tumors that affect neurologic function by pressing on the surrounding parts of the brain. Pediatric low-grade glioma (pLGG) is the most common childhood brain tumors. Patients with pLGG often have a significant life-long disabilities. The most common mutations in pLGG are in the mitogen-activated protein kinase (MAPK) pathway including tumor suppressor neurofibromin (NF1), and the oncogene BRAF. BRAF activates MEK1/2, which activates of ERK1/2, leading to tumorigenesis. BRAFV600E mutation results in the activation segment of the kinase “monomeric form of BRAF”, leading to constitutive activation of MAP kinase and mTOR pathways Combination treatment of TAK228 (mTOR inhibitor) and trametinib (MEK1/2 inhibitor), suppressed both mTOR and MAP kinase pathways and inhibited BRAFV600E glioma tumor growth. To further investigate and understand the molecular mechanism of TAK228 and trametinib combinatorial efficacy, we performed comprehensive proteomic analysis of BRAFV600E glioma tumors treated with TAK228 and trametinib. We found increased levels of many proteins in the glycolysis and TCA cycle. Specifically we found increases at the protein level in citrate synthase, aconitase and malate dehydrogenase in the TCA cycle. In glycolysis, we observed increased glucose transporter expression (SLC2A1), increased hexokinase 2, and increased GAPDH. Upregualtion of these proteins may represent attempts to bypass the effects of mTOR and MAP kinase blockade on the activity of these pathways. We are currently performing flux metabolic profiling using uniformly labeled glucose to assess the activity of the pathways after combined mTOR and MAP kinase blockade. Our results may increase our understanding of how glioma cells use glucose and how mTOR and MAP kinase pathway inhibition affects basic metabolic pathways in glioma cells.