GENE-38. IDH1MUT INDUCES N6-METHYLADENOSINE (m6A) RNA HYPERMETHYLATION VIA D-2-HG IN GLIOMA. (11th November 2019)

• Record Type: Journal Article
• Authors: Pianka, Sean; Li, Tie; Ji, Matthew; Lai, Albert
• Is Part Of: Neuro-oncology. Volume 21(2019)Supplement 6
• Page Start: vi105
• Page End: vi106
• Publication Date: 2019-11-11
• Subjects: Brain Neoplasms -- Periodicals; Brain -- Tumors -- Periodicals; Brain -- Cancer -- Periodicals; Nervous system -- Cancer -- Periodicals; 616.99481
• DOI: 10.1093/neuonc/noz175.440
• Languages: English
• ISSNs: 1522-8517

Abstract

Abstract: INTRODUCTION: IDH1 MUT confers slower tumor growth rates and improved prognoses for glioma patients, but the precise mechanisms underlying these clinically relevant benefits remain largely unknown. IDH1 MUT gliomas produce high levels of D-2-HG, a putative oncometabolite that inhibits a range of α-ketoglutarate-dependent dioxygenases. D-2-HG-mediated inhibition of TET-family proteins involved in DNA demethylation is known to be a key driver leading to the oncogenic DNA hypermethylation phenotype (known as G-CIMP) seen in IDH1 MUT gliomas. Recent evidence indicates that D-2-HG also functionally inhibits FTO and AlkBH5, two dioxygenases responsible for demethylation of RNA N 6 -methyladenosine (m6A) sites. This study sought to determine if D-2-HG mediates an increase in m6A content in IDH1 MUT gliomas. METHODS: Total RNA was isolated from patient tumor samples, patient-derived gliomaspheres, human embryonic kidney cell (HEK293T), normal human astrocyte (NHA), and U87 glioma model systems expressing either IDH1 MUT or IDH1 WT . Relative abundance of m6A modifications was determined both quantitatively and qualitatively using colorimetric ELISA-like assays and m6A-antibody dot blots, respectively. RESULTS: Quantification of m6A abundance in IDH1 MUT patient tumor samples and patient-derived gliomaspheres revealed an increase in m6A content compared to IDH1 WT samples. Forced expression of IDH1 MUT in HEK293T, NHA, and U87 cells increased intracellular D-2-HG content and global m6A abundance in purified RNA. Additionally, D-2-HG treatment of IDH1 WT cell lines increased m6A abundance, including in IDH1 WT gliomaspheres. Conversely, inhibition of D-2-HG generation in IDH1 MUT cell lines decreased m6A abundance. Data will also be presented suggesting that increased m6A abundance is associated with decreased cellular proliferation. CONCLUSIONS: These results indicate that increased intracellular D-2-HG arising in the context of IDH1 MUT mediates increases in RNA m6A methylation in glioma. The association with m6A hypermethylation and reduced growth suggests that RNA methylation provides a novel therapeutic target.