Myc targeted CDK18 promotes ATR and homologous recombination to mediate PARP inhibitor resistance in glioblastoma.

PARP inhibitors (PARPis) have clinical efficacy in BRCA-deficient cancers, but not BRCA-intact tumors, including glioblastoma (GBM). We show that MYC or MYCN amplification in patient-derived glioblastoma stem-like cells (GSCs) generates sensitivity to PARPi via Myc-mediated transcriptional repression of CDK18, while most tumors without amplification are not sensitive. In response to ...
PARPi, CDK18 facilitates ATR activation by interacting with ATR and regulating ATR-Rad9/ATR-ETAA1 interactions; thereby promoting homologous recombination (HR) and PARPi resistance. CDK18 knockdown or ATR inhibition in GSCs suppressed HR and conferred PARPi sensitivity, with ATR inhibitors synergizing with PARPis or sensitizing GSCs. ATR inhibitor VE822 combined with PARPi extended survival of mice bearing GSC-derived orthotopic tumors, irrespective of PARPi-sensitivity. These studies identify a role of CDK18 in ATR-regulated HR. We propose that combined blockade of ATR and PARP is an effective strategy for GBM, even for low-Myc GSCs that do not respond to PARPi alone, and potentially other PARPi-refractory tumors.
Mesh Terms:
Animals, Antigens, Surface, Ataxia Telangiectasia Mutated Proteins, Cell Cycle Proteins, Cyclin-Dependent Kinases, Drug Resistance, Neoplasm, Female, Glioblastoma, Homologous Recombination, Humans, Mice, Mice, SCID, N-Myc Proto-Oncogene Protein, Neoplastic Stem Cells, Poly (ADP-Ribose) Polymerase-1, Poly(ADP-ribose) Polymerase Inhibitors, Protein Binding, Proto-Oncogene Proteins c-myc, Xenograft Model Antitumor Assays
Nat Commun
Date: Jul. 02, 2019
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