Poly[ADP-ribose] polymerase (PARP) inhibitors, which selectively kills homologous recombination (HR) repair-deficient cancer cells, are widely employed to treat cancer patients harboring BRCA1/2 mutations. However, they display limited efficacy in tumors with wild-type (WT) BRCA1/2. Thus, it is crucial to identify new druggable HR repair regulators and improve the therapeutic efficacy of PARP inhibitors via combination therapies in BRCA1/2-WT tumors. Here, we show that the depletion of ribonucleotide reductase (RNR) subunit p53R2 impairs HR repair and sensitizes BRCA1/2-WT cancer cells to PARP inhibition. We further demonstrate that the loss of p53R2 leads to a decrease of HR repair factor CtIP, as a result of dNTPs shortage-induced ubiquitination of CtIP. Moreover, we identify that casein kinase II (CK2) phosphorylates p53R2 at its ser20, which subsequently activates RNR for dNTPs production. Therefore, pharmacologic inhibition of the CK2-mediated phosphorylation of p53R2 compromises its HR repair capacity in BRCA1/2-WT cancer cells, which renders these cells susceptible to PARP inhibition in vitro and in vivo. Therefore, our study reveals a novel strategy to inhibit HR repair activity and convert BRCA1/2-proficient cancers to be susceptible to PARP inhibitors via synthetic lethal combination.
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Cohen MS, Chang P. Insights into the biogenesis, function, and regulation of ADP-ribosylation. Nat Chem Biol. 2018;14:236–43.
Spiegel JO, Van Houten B, Durrant JD. PARP1: Structural insights and pharmacological targets for inhibition. DNA Repair (Amst). 2021;103:103125.
Zhao B, Rothenberg E, Ramsden DA, Lieber MR. The molecular basis and disease relevance of non-homologous DNA end joining. Nat Rev Mol Cell Biol. 2020;21:765–81.
Demin AA, Hirota K, Tsuda M, Adamowicz M, Hailstone R, Brazina J, et al. XRCC1 prevents toxic PARP1 trapping during DNA base excision repair. Mol Cell. 2021;81:3018–30 e3015.
Zandarashvili L, Langelier MF, Velagapudi UK, Hancock MA, Steffen JD, Billur R, et al. Structural basis for allosteric PARP-1 retention on DNA breaks. Science. 2020;368:eaax6367.
Reynolds P, Cooper S, Lomax M, O’Neill P. Disruption of PARP1 function inhibits base excision repair of a sub-set of DNA lesions. Nucleic Acids Res. 2015;43:4028–38.
D’Andrea AD. Mechanisms of PARP inhibitor sensitivity and resistance. DNA Repair (Amst). 2018;71:172–6.
Peng Y, Liao Q, Tan W, Peng C, Hu Z, Chen Y, et al. The deubiquitylating enzyme USP15 regulates homologous recombination repair and cancer cell response to PARP inhibitors. Nat Commun. 2019;10:1224.
Verma P, Zhou Y, Cao Z, Deraska PV, Deb M, Arai E, et al. ALC1 links chromatin accessibility to PARP inhibitor response in homologous recombination-deficient cells. Nat Cell Biol. 2021;23:160–71.
Zhang S, Peng X, Li X, Liu H, Zhao B, Elkabets M, et al. BKM120 sensitizes glioblastoma to the PARP inhibitor rucaparib by suppressing homologous recombination repair. Cell Death Dis. 2021;12:546.
Chopra N, Tovey H, Pearson A, Cutts R, Toms C, Proszek P, et al. Homologous recombination DNA repair deficiency and PARP inhibition activity in primary triple negative breast cancer. Nat Commun. 2020;11:2662.
Lord CJ, Ashworth A. PARP inhibitors: Synthetic lethality in the clinic. Science. 2017;355:1152–8.
Scully R, Panday A, Elango R, Willis NA. DNA double-strand break repair-pathway choice in somatic mammalian cells. Nat Rev Mol Cell Biol. 2019;20:698–714.
Ceccaldi R, Rondinelli B, D’Andrea AD. Repair pathway choices and consequences at the double-strand break. Trends Cell Biol. 2016;26:52–64.
Bouwman P, Aly A, Escandell JM, Pieterse M, Bartkova J, van der Gulden H, et al. 53BP1 loss rescues BRCA1 deficiency and is associated with triple-negative and BRCA-mutated breast cancers. Nat Struct Mol Biol. 2010;17:688–95.
Lee D, Apelt K, Lee SO, Chan HR, Luijsterburg MS, Leung JWC, et al. ZMYM2 restricts 53BP1 at DNA double-strand breaks to favor BRCA1 loading and homologous recombination. Nucleic Acids Res. 2022;50:3922–43.
Geisler JP, Hatterman-Zogg MA, Rathe JA, Buller RE. Frequency of BRCA1 dysfunction in ovarian cancer. J Natl Cancer Inst. 2002;94:61–7.
Krais JJ, Johnson N. BRCA1 Mutations in Cancer: Coordinating Deficiencies in Homologous Recombination with Tumorigenesis. Cancer Res. 2020;80:4601–9.
Chen G, Luo Y, Warncke K, Sun Y, Yu DS, Fu H, et al. Acetylation regulates ribonucleotide reductase activity and cancer cell growth. Nat Commun. 2019;10:3213.
Pontarin G, Ferraro P, Bee L, Reichard P, Bianchi V. Mammalian ribonucleotide reductase subunit p53R2 is required for mitochondrial DNA replication and DNA repair in quiescent cells. Proc Natl Acad Sci USA. 2012;109:13302–7.
Pontarin G, Ferraro P, Hakansson P, Thelander L, Reichard P, Bianchi V. p53R2-dependent ribonucleotide reduction provides deoxyribonucleotides in quiescent human fibroblasts in the absence of induced DNA damage. J Biol Chem. 2007;282:16820–8.
McIlwraith MJ, Vaisman A, Liu Y, Fanning E, Woodgate R, West SC. Human DNA polymerase eta promotes DNA synthesis from strand invasion intermediates of homologous recombination. Mol Cell. 2005;20:783–92.
Chen G, Magis AT, Xu K, Park D, Yu DS, Owonikoko TK, et al. Targeting Mcl-1 enhances DNA replication stress sensitivity to cancer therapy. J Clin Invest. 2018;128:500–16.
Mali P, Yang L, Esvelt KM, Aach J, Guell M, DiCarlo JE, et al. RNA-guided human genome engineering via Cas9. Science. 2013;339:823–6.
Sak A, Stuschke M. Use of gammaH2AX and other biomarkers of double-strand breaks during radiotherapy. Semin Radiat Oncol. 2010;20:223–31.
Moller P, Azqueta A, Boutet-Robinet E, Koppen G, Bonassi S, Milic M, et al. Minimum Information for Reporting on the Comet Assay (MIRCA): recommendations for describing comet assay procedures and results. Nat Protoc. 2020;15:3817–26.
Hariharasudhan G, Jeong SY, Kim MJ, Jung SM, Seo G, Moon JR, et al. TOPORS-mediated RAD51 SUMOylation facilitates homologous recombination repair. Nucleic Acids Res. 2022;50:1501–16.
Shen J, Zhao Y, Pham NT, Li Y, Zhang Y, Trinidad J, et al. Deciphering the mechanism of processive ssDNA digestion by the Dna2-RPA ensemble. Nat Commun. 2022;13:359.
Bartek J Jr., Merchut-Maya JM, Maya-Mendoza A, Fornara O, Rahbar A, Brochner CB, et al. Cancer cell stemness, responses to experimental genotoxic treatments, cytomegalovirus protein expression and DNA replication stress in pediatric medulloblastomas. Cell Cycle. 2020;19:727–41.
Chen G, Chen J, Qiao Y, Shi Y, Liu W, Zeng Q, et al. ZNF830 mediates cancer chemoresistance through promoting homologous-recombination repair. Nucleic Acids Res. 2018;46:1266–79.
Lafranchi L, de Boer HR, de Vries EG, Ong SE, Sartori AA, van Vugt MA. APC/C(Cdh1) controls CtIP stability during the cell cycle and in response to DNA damage. EMBO J. 2014;33:2860–79.
Qu J, Sun W, Zhong J, Lv H, Zhu M, Xu J, et al. Phosphoglycerate mutase 1 regulates dNTP pool and promotes homologous recombination repair in cancer cells. J Cell Biol. 2017;216:409–24.
Zhao X, Wei Y, Chu YY, Li Y, Hsu JM, Jiang Z, et al. Phosphorylation and stabilization of PD-L1 by CK2 suppresses dendritic cell function. Cancer Res. 2022;82:2185–95.
Loizou JI, El-Khamisy SF, Zlatanou A, Moore DJ, Chan DW, Qin J, et al. The protein kinase CK2 facilitates repair of chromosomal DNA single-strand breaks. Cell. 2004;117:17–28.
Tian L, Chen C, Guo Y, Zhang F, Mi J, Feng Q, et al. mTORC2 regulates ribonucleotide reductase to promote DNA replication and gemcitabine resistance in non-small cell lung cancer. Neoplasia. 2021;23:643–52.
Chen SH, Yu X. Targeting dePARylation selectively suppresses DNA repair-defective and PARP inhibitor-resistant malignancies. Sci Adv. 2019;5:eaav4340.
Salvi M, Borgo C, Pinna LA, Ruzzene M. Targeting CK2 in cancer: a valuable strategy or a waste of time? Cell Death Discov. 2021;7:325.
Kamel D, Gray C, Walia JS, Kumar V. PARP Inhibitor Drugs in the Treatment of Breast, Ovarian, Prostate and Pancreatic Cancers: An Update of Clinical Trials. Curr Drug Targets. 2018;19:21–37.
Lee A, Moon BI, Kim TH. BRCA1/BRCA2 Pathogenic Variant Breast Cancer: Treatment and Prevention Strategies. Ann Lab Med. 2020;40:114–21.
Shah S, Rachmat R, Enyioma S, Ghose A, Revythis A, Boussios S. BRCA Mutations in Prostate Cancer: Assessment, Implications and Treatment Considerations. Int J Mol Sci. 2021;22:12628.
Wong W, Raufi AG, Safyan RA, Bates SE, Manji GA. BRCA Mutations in Pancreas Cancer: Spectrum, Current Management, Challenges and Future Prospects. Cancer Manag Res. 2020;12:2731–42.
Foskolou IP, Jorgensen C, Leszczynska KB, Olcina MM, Tarhonskaya H, Haisma B, et al. Ribonucleotide Reductase Requires Subunit Switching in Hypoxia to Maintain DNA Replication. Mol Cell. 2017;66:206–220 e209.
Spies J, Polasek-Sedlackova H, Lukas J, Somyajit K. Homologous Recombination as a Fundamental Genome Surveillance Mechanism during DNA Replication. Genes (Basel). 2021;12:1960.
Schwarz R, Richter A, Ito ERD, Murua Escobar H, Junghanss C, Hinz B. Validation of an LC-MS/MS Method for the Quantification of the CK2 Inhibitor Silmitasertib (CX-4945) in Human Plasma. Molecules. 2022;27:2394.
Dodson GE, Limbo O, Nieto D, Russell P. Phosphorylation-regulated binding of Ctp1 to Nbs1 is critical for repair of DNA double-strand breaks. Cell Cycle. 2010;9:1516–22.
Olsen BB, Wang SY, Svenstrup TH, Chen BP, Guerra B. Protein kinase CK2 localizes to sites of DNA double-strand break regulating the cellular response to DNA damage. BMC Mol Biol. 2012;13:7.
Strom CE, Mortusewicz O, Finch D, Parsons JL, Lagerqvist A, Johansson F, et al. CK2 phosphorylation of XRCC1 facilitates dissociation from DNA and single-strand break formation during base excision repair. DNA Repair (Amst). 2011;10:961–9.
von Morgen P, Burdova K, Flower TG, O’Reilly NJ, Boulton SJ, Smerdon SJ, et al. MRE11 stability is regulated by CK2-dependent interaction with R2TP complex. Oncogene. 2017;36:4943–50.
Becherel OJ, Jakob B, Cherry AL, Gueven N, Fusser M, Kijas AW, et al. CK2 phosphorylation-dependent interaction between aprataxin and MDC1 in the DNA damage response. Nucleic Acids Res. 2010;38:1489–503.
Feng H, Lu J, Song X, Thongkum A, Zhang F, Lou L, et al. CK2 kinase-mediated PHF8 phosphorylation controls TopBP1 stability to regulate DNA replication. Nucleic Acids Res. 2020;48:10940–52.
Guerra B, Iwabuchi K, Issinger OG. Protein kinase CK2 is required for the recruitment of 53BP1 to sites of DNA double-strand break induced by radiomimetic drugs. Cancer Lett. 2014;345:115–23.
We would like to thank to Dr. Congcong Chen (Jinan University) and Mr. Yanguan Guo (Jinan University) for their technique supports.
This work is supported by National Natural Science Foundation of China (82073042 to GC; 82272692 to DK. Li), Guangdong Basic and Applied Basic Research Foundation (2022B1515020105 to GC) and Natural Science Foundation of Zhejiang Province (LY21H160025 to YQ).
The authors declare no competing interests.
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Wang, C., Tian, L., He, Q. et al. Targeting CK2-mediated phosphorylation of p53R2 sensitizes BRCA-proficient cancer cells to PARP inhibitors. Oncogene 42, 2971–2984 (2023). https://doi.org/10.1038/s41388-023-02812-5