title: The Error-Prone DNA Polymerase κ Promotes Temozolomide Resistance in Glioblastoma through Rad17-Dependent Activation of ATR-Chk1 Signaling.
abstract: The acquisition of drug resistance is a persistent clinical problem limiting the successful treatment of human cancers, including glioblastoma (GBM). However, the molecular mechanisms by which initially chemoresponsive tumors develop therapeutic resistance remain poorly understood. In this study, we report that Pol κ, an error-prone polymerase that participates in translesion DNA synthesis, was significantly upregulated in GBM cell lines and tumor tissues following temozolomide treatment. Overexpression of Pol κ in temozolomide-sensitive GBM cells conferred resistance to temozolomide, whereas its inhibition markedly sensitized resistant cells to temozolomide in vitro and in orthotopic xenograft mouse models. Mechanistically, depletion of Pol κ disrupted homologous recombination (HR)-mediated repair and restart of stalled replication forks, impaired the activation of ATR-Chk1 signaling, and delayed cell-cycle re-entry and progression. Further investigation of the relationship between Pol κ and temozolomide revealed that Pol κ inactivation facilitated temozolomide-induced Rad17 ubiquitination and proteasomal degradation, subsequently silencing ATR-Chk1 signaling and leading to defective HR repair and the reversal of temozolomide resistance. Moreover, overexpression of Rad17 in Pol κ-depleted GBM cells restored HR efficiency, promoted the clearance of temozolomide-induced DNA breaks, and desensitized cells to the cytotoxic effects of temozolomide observed in the absence of Pol κ. Finally, we found that Pol κ overexpression correlated with poor prognosis in GBM patients undergoing temozolomide therapy. Collectively, our findings identify a potential mechanism by which GBM cells develop resistance to temozolomide and suggest that targeting the DNA damage tolerance pathway may be beneficial for overcoming resistance. Cancer Res; 76(8); 2340-53. ©2016 AACR.
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Chenghao
authors.initials: C
authors.lastname: Peng
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Zhengxin
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Hematology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Neurosurgery, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Wang
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Wenjin
authors.initials: W
authors.lastname: Qiu
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Xu
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Luo
authors.affiliation: Mouse Biology Unit, European Molecular Biology Laboratory, Monterotondo, Italy.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Ministry of Education and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China. Chinese Glioma Cooperative Group (CGCG).
authors.forename: Yongping
authors.initials: Y
authors.lastname: You
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China. Chinese Glioma Cooperative Group (CGCG).
authors.forename: Ning
authors.initials: N
authors.lastname: Liu
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China. Chinese Glioma Cooperative Group (CGCG). hbwang@njmu.edu.cn.
authors.forename: Huibo
authors.initials: H
authors.lastname: Wang
mesh_terms: D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology*; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology*; D064593:Heterografts; D006801:Humans; D051379:Mice; D015398:Signal Transduction; D000077204:Temozolomide; D000099270:Y-Family DNA Polymerases
chemical_list: D018906:Antineoplastic Agents, Alkylating; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D004259:DNA-Directed DNA Polymerase; D003606:Dacarbazine; D000077204:Temozolomide; C113575:Rad17 protein, human; C576597:ATR protein, human; C404302:POLK protein, human; D000099270:Y-Family DNA Polymerases