Authors

Brendan Mullan, Wayne State University School of MedicineFollow
Tingting Qin, Department of Computational Medicine and Bioinformatics, University of Michigan Medical School
Ruby Siada, Department of Pediatrics, Division of Pediatric Hematology-Oncology, University of Michigan Medical School
Carla Danussi, Department of Translational Molecular Pathology, University of Texas MD Anderson Cancer Center
Jacqueline Brosnan-Cashman, Department of Pathology, Johns Hopkins University School of Medicine
Drew Pratt, Department of Pathology, University of Michigan Medical School
Taylor Garcia, Department of Pediatrics, Division of Pediatric Hematology-Oncology, University of Michigan Medical School
Viveka Nand Yadav, Department of Pediatrics, Division of Pediatric Hematology-Oncology, University of Michigan Medical School
Xinyi Zhao, Department of Radiation Oncology, University of Michigan Medical School
Meredith Morgan, Department of Radiation Oncology, University of Michigan Medical School
Sriram Venneti, Department of Pathology, University of Michigan Medical School
Alan Meeker, Department of Pathology, Johns Hopkins University School of Medicine
Alnawaz Rehemtulla, Department of Computational Medicine and Bioinformatics, University of Michigan Medical School
Pedro Lowenstein, Departments of Neurosurgery and Cell and Developmental Biology, University of Michigan Medical School
Maria Castro, Departments of Neurosurgery and Cell and Developmental Biology, University of Michigan Medical School
Carl Koschmann, Department of Pediatrics, Division of Pediatric Hematology-Oncology, University of Michigan Medical School

Research Mentor Name

Carl Koschmann M.D.

Research Mentor Email Address

ckoschma@med.umich.edu

Institution / Department

Department of Pediatrics, Division of Pediatric Hematology-Oncology, University of Michigan Medical School

Document Type

Research Abstract

Research Type

basicbio

Level of Research

no

Abstract

ATRX is a histone chaperone protein recurrently mutated in pediatric glioma. The mechanism which mediates the proliferative advantage of ATRX loss in pediatric glioma remains unexplained. Recent data revealed a distinct pattern of DNA binding sites of the ATRX protein using ChIP-seq in mouse neuronal precursor cells (mNPCs). Using the ATRX peaks identified in p53-/- mNPCs, we confirmed that ATRX binding sites were significantly enriched in gene promoters (p < 0.0001) and CpG islands (p < 0.0001) compared with random regions. Gene set enrichment (GSE) analysis identified that cell cycle and regulation of cell cycle were among the most significantly enriched gene sets (p=2.52e-16 and 1.61e-9, respectively). We found that ATRX loss resulted in dysfunction of G2/M checkpoint maintenance: (1) ATRX-deficient pediatric glioblastoma (GBM) cells exhibited a seven-fold increase in mitotic index at 16 hours after sub-lethal radiation, and (2) murine GBM cells with ATRX knockdown demonstrated impaired pChk1 signaling on western blot at multiple time points after radiation compared to controls (p=0.0187). Notably, the ATM signaling (pChk2) remained intact in those cells, suggesting a potential therapeutic target. ATRX-deficient mouse cells were uniquely sensitive to ATM inhibitors at 1 uM alongside 8 Gy radiation compared to controls with intact ATRX (AZD0156: p=0.0027 and AZD01390: p=0.0436). Mice intra-cranially implanted with ATRX-deficient GBM cells showed improved survival (n=10, p=0.0018) when treated with AZD0156 combined with radiation. Our findings suggest that ATRX loss in glioma results in unique sensitivity to ATM inhibition via epigenetic dysregulation of G2/M checkpoint maintenance.

Disciplines

Medicine and Health Sciences | Neoplasms | Oncology | Pediatrics | Radiation Medicine

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