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

• Published in: Nature communications Vol. 10; no. 1; pp. 2910 - 18
• Main Authors: Ning, Jian-Fang, Stanciu, Monica, Humphrey, Melissa R, Gorham, Joshua, Wakimoto, Hiroko, Nishihara, Reiko, Lees, Jacqueline, Zou, Lee, Martuza, Robert L, Wakimoto, Hiroaki, Rabkin, Samuel D
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 02.07.2019; Nature Publishing Group UK; Nature Portfolio
• Subjects: Amplification; Animals; Antigens, Surface - genetics; Antigens, Surface - metabolism; Ataxia Telangiectasia Mutated Proteins - genetics; Ataxia Telangiectasia Mutated Proteins - metabolism; Brain cancer; Brain research; Cell cycle; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cyclin-dependent kinases; Cyclin-Dependent Kinases - genetics; Cyclin-Dependent Kinases - metabolism; Cytotoxicity; Drug Resistance, Neoplasm; FDA approval; Female; Gene expression; Gene silencing; Glioblastoma; Glioblastoma - drug therapy; Glioblastoma - genetics; Glioblastoma - metabolism; Homologous Recombination; Homology; Humans; Inhibitors; Kinases; Laboratories; Medical research; Medical schools; Mice; Mice, SCID; Mutation; Myc protein; N-Myc Proto-Oncogene Protein - genetics; N-Myc Proto-Oncogene Protein - metabolism; Neoplastic Stem Cells - metabolism; Neurosurgery; Poly (ADP-Ribose) Polymerase-1 - genetics; Poly (ADP-Ribose) Polymerase-1 - metabolism; Poly(ADP-ribose) polymerase; Poly(ADP-ribose) Polymerase Inhibitors - administration & dosage; Protein Binding; Proto-Oncogene Proteins c-myc - genetics; Proto-Oncogene Proteins c-myc - metabolism; Rad9 protein; Sensitivity; Sensitizing; Transcription factors; Tumors; Xenograft Model Antitumor Assays
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-10993-5

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.