Table S2. Liquid Chromatography and Mass Spectrometry Measurement of 2-hydroxyglutarate in the Conditioned Media of mIDH1 GCCs untreated, treated with vehicle (DMSO), or mIDH1 inhibitor (AGI-5198 or DS1001b)
Funding
National Institute of Neurological Disorders and Stroke (NINDS)
United States Department of Health and Human Services
Find out more...Rogel Cancer Center, University of Michigan (Rogel Cancer Center)
National Cancer Institute (NCI)
United States Department of Health and Human Services
Find out more...Pediatric Brain Tumor Foundation (PBTF)
Leah's Happy Hearts Foundation
Ian's Friends Foundation
ChadTough Foundation (Chad Tough Foundation)
Smiles for Sophie Forever Foundation
Horace H. Rackham School of Graduate Studies, University of Michigan (Rackham U-M)
ARTICLE ABSTRACT
Mutant isocitrate dehydrogenase 1 (mIDH1) alters the epigenetic regulation of chromatin, leading to a hypermethylation phenotype in adult glioma. This work focuses on identifying gene targets epigenetically dysregulated by mIDH1 to confer therapeutic resistance to ionizing radiation (IR).
We evaluated changes in the transcriptome and epigenome in a radioresistant mIDH1 patient-derived glioma cell culture (GCC) following treatment with an mIDH1-specific inhibitor, AGI-5198. We identified Zinc Finger MYND-Type Containing 8 (ZMYND8) as a potential target of mIDH1 reprogramming. We suppressed ZMYND8 expression by shRNA knockdown and genetic knockout (KO) in mIDH1 glioma cells and then assessed cellular viability to IR. We assessed the sensitivity of mIDH1 GCCS to pharmacologic inhibition of ZMYND8-interacting partners: HDAC, BRD4, and PARP.
Inhibition of mIDH1 leads to an upregulation of gene networks involved in replication stress. We found that the expression of ZMYND8, a regulator of DNA damage response, was decreased in three patient-derived mIDH1 GCCs after treatment with AGI-5198. Knockdown of ZMYND8 expression sensitized mIDH1 GCCs to radiotherapy marked by decreased cellular viability. Following IR, mIDH1 glioma cells with ZMYND8 KO exhibit significant phosphorylation of ATM and sustained γH2AX activation. ZMYND8 KO mIDH1 GCCs were further responsive to IR when treated with either BRD4 or HDAC inhibitors. PARP inhibition further enhanced the efficacy of radiotherapy in ZMYND8 KO mIDH1 glioma cells.
These findings indicate the impact of ZMYND8 in the maintenance of genomic integrity and repair of IR-induced DNA damage in mIDH1 glioma.See related commentary by Sachdev et al., p. 1648
