1
|
Repair of programmed DNA lesions in antibody class switch recombination: common and unique features. ACTA ACUST UNITED AC 2021; 2:115-125. [PMID: 33817557 PMCID: PMC7996122 DOI: 10.1007/s42764-021-00035-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 02/22/2021] [Accepted: 03/04/2021] [Indexed: 01/31/2023]
Abstract
The adaptive immune system can diversify the antigen receptors to eliminate various pathogens through programmed DNA lesions at antigen receptor genes. In immune diversification, general DNA repair machineries are applied to transform the programmed DNA lesions into gene mutation or recombination events with common and unique features. Here we focus on antibody class switch recombination (CSR), and review the initiation of base damages, the conversion of damaged base to DNA double-strand break, and the ligation of broken ends. With an emphasis on the unique features in CSR, we discuss recent advances in the understanding of DNA repair/replication coordination, and ERCC6L2-mediated deletional recombination. We further elaborate the application of CSR in end-joining, resection and translesion synthesis assays. In the time of the COVID-19 pandemic, we hope it help to understand the generation of therapeutic antibodies.
Collapse
|
2
|
Wang XS, Lee BJ, Zha S. The recent advances in non-homologous end-joining through the lens of lymphocyte development. DNA Repair (Amst) 2020; 94:102874. [PMID: 32623318 DOI: 10.1016/j.dnarep.2020.102874] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/16/2020] [Accepted: 05/24/2020] [Indexed: 12/17/2022]
Abstract
Lymphocyte development requires ordered assembly and subsequent modifications of the antigen receptor genes through V(D)J recombination and Immunoglobulin class switch recombination (CSR), respectively. While the programmed DNA cleavage events are initiated by lymphocyte-specific factors, the resulting DNA double-strand break (DSB) intermediates activate the ATM kinase-mediated DNA damage response (DDR) and rely on the ubiquitously expressed classical non-homologous end-joining (cNHEJ) pathway including the DNA-dependent protein kinase (DNA-PK), and, in the case of CSR, also the alternative end-joining (Alt-EJ) pathway, for repair. Correspondingly, patients and animal models with cNHEJ or DDR defects develop distinct types of immunodeficiency reflecting their specific DNA repair deficiency. The unique end-structure, sequence context, and cell cycle regulation of V(D)J recombination and CSR also provide a valuable platform to study the mechanisms of, and the interplay between, cNHEJ and DDR. Here, we compare and contrast the genetic consequences of DNA repair defects in V(D)J recombination and CSR with a focus on the newly discovered cNHEJ factors and the kinase-dependent structural roles of ATM and DNA-PK in animal models. Throughout, we try to highlight the pending questions and emerging differences that will extend our understanding of cNHEJ and DDR in the context of primary immunodeficiency and lymphoid malignancies.
Collapse
Affiliation(s)
- Xiaobin S Wang
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY 10032, United States; Graduate Program of Pathobiology and Molecular Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY 10032, United States
| | - Brian J Lee
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY 10032, United States
| | - Shan Zha
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY 10032, United States; Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY 10032, United States; Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY 10032, United States; Department of Immunology and Microbiology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY 10032, United States.
| |
Collapse
|
3
|
Goullet de Rugy T, Bashkurov M, Datti A, Betous R, Guitton-Sert L, Cazaux C, Durocher D, Hoffmann JS. Excess Polθ functions in response to replicative stress in homologous recombination-proficient cancer cells. Biol Open 2016; 5:1485-1492. [PMID: 27612511 PMCID: PMC5087683 DOI: 10.1242/bio.018028] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
DNA polymerase theta (Polθ) is a specialized A-family DNA polymerase that functions in processes such as translesion synthesis (TLS), DNA double-strand break repair and DNA replication timing. Overexpression of POLQ, the gene encoding Polθ, is a prognostic marker for an adverse outcome in a wide range of human cancers. While increased Polθ dosage was recently suggested to promote survival of homologous recombination (HR)-deficient cancer cells, it remains unclear whether POLQ overexpression could be also beneficial to HR-proficient cancer cells. By performing a short interfering (si)RNA screen in which genes encoding druggable proteins were knocked down in Polθ-overexpressing cells as a means to uncover genetic vulnerabilities associated with POLQ overexpression, we could not identify genes that were essential for viability in Polθ-overexpressing cells in normal growth conditions. We also showed that, upon external DNA replication stress, Polθ expression promotes cell survival and limits genetic instability. Finally, we report that POLQ expression correlates with the expression of a set of HR genes in breast, lung and colorectal cancers. Collectively, our data suggest that Polθ upregulation, besides its importance for survival of HR-deficient cancer cells, may be crucial also for HR-proficient cells to better tolerate DNA replication stress, as part of a global gene deregulation response, including HR genes. Summary: Our work suggests that Polθ upregulation may be crucial for homologous recombination (HR)-proficient cells to better tolerate DNA replication stress, as part of a global gene deregulation response, including HR genes.
Collapse
Affiliation(s)
- T Goullet de Rugy
- UMR1037, Le Centre de Recherches en Cancérologie de Toulouse (CRCT), 2 Avenue Hubert, Curien CS 53717, Toulouse 31037, Cedex 1, France UMR1037, CRCT, Université Toulouse, III-Paul Sabatier, Toulouse F-31000, France Equipe Labellisée Ligue Contre le Cancer, Toulouse F-31000, France
| | - M Bashkurov
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5
| | - A Datti
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5 Department of Agricultural, Food and Environmental Sciences, University of Perugia, Perugia 06121-06135, Italy
| | - R Betous
- UMR1037, Le Centre de Recherches en Cancérologie de Toulouse (CRCT), 2 Avenue Hubert, Curien CS 53717, Toulouse 31037, Cedex 1, France UMR1037, CRCT, Université Toulouse, III-Paul Sabatier, Toulouse F-31000, France Equipe Labellisée Ligue Contre le Cancer, Toulouse F-31000, France
| | - L Guitton-Sert
- UMR1037, Le Centre de Recherches en Cancérologie de Toulouse (CRCT), 2 Avenue Hubert, Curien CS 53717, Toulouse 31037, Cedex 1, France UMR1037, CRCT, Université Toulouse, III-Paul Sabatier, Toulouse F-31000, France Equipe Labellisée Ligue Contre le Cancer, Toulouse F-31000, France
| | - C Cazaux
- UMR1037, Le Centre de Recherches en Cancérologie de Toulouse (CRCT), 2 Avenue Hubert, Curien CS 53717, Toulouse 31037, Cedex 1, France UMR1037, CRCT, Université Toulouse, III-Paul Sabatier, Toulouse F-31000, France Equipe Labellisée Ligue Contre le Cancer, Toulouse F-31000, France
| | - D Durocher
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5
| | - J S Hoffmann
- UMR1037, Le Centre de Recherches en Cancérologie de Toulouse (CRCT), 2 Avenue Hubert, Curien CS 53717, Toulouse 31037, Cedex 1, France UMR1037, CRCT, Université Toulouse, III-Paul Sabatier, Toulouse F-31000, France Equipe Labellisée Ligue Contre le Cancer, Toulouse F-31000, France
| |
Collapse
|
4
|
Dai CH, Chen P, Li J, Lan T, Chen YC, Qian H, Chen K, Li MY. Co-inhibition of pol θ and HR genes efficiently synergize with cisplatin to suppress cisplatin-resistant lung cancer cells survival. Oncotarget 2016; 7:65157-65170. [PMID: 27533083 PMCID: PMC5323145 DOI: 10.18632/oncotarget.11214] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 07/18/2016] [Indexed: 12/14/2022] Open
Abstract
Cisplatin exert its anticancer effect by creating intrastrand and interstrand DNA cross-links which block DNA replication and is a major drug used to treat lung cancer. However, the main obstacle of the efficacy of treatment is drug resistance. Here, we show that expression of translesion synthesis (TLS) polymerase Q (POLQ) was significantly elevated by exposure of lung cancer cells A549/DR (a cisplatin-resistant A549 cell line) to cisplatin. POLQ expression correlated inversely with homologous recombination (HR) activity. Co-depletion of BRCA2 and POLQ by siRNA markedly increased sensitivity of A549/DR cells to cisplatin, which was accompanied with impairment of double strand breaks (DSBs) repair reflected by prominent cell cycle checkpoint response, increased chromosomal aberrations and persistent colocalization of p-ATM and 53BP1 foci induced by cisplatin. Thus, co-knockdown of POLQ and HR can efficiently synergize with cisplatin to inhibit A549/DR cell survival by inhibiting DNA DSBs repair. Similar results were observed in A549/DR cells co-depleted of BRCA2 and POLQ following BMN673 (a PARP inhibitor) treatment. Importantly, the sensitization effects to cisplatin and BMN673 in A549/DR cells by co-depleting BRCA2 and POLQ was stronger than those by co-depleting BRCA2 and other TLS factors including POLH, REV3, or REV1. Our results indicate that there is a synthetic lethal relationship between pol θ-mediated DNA repair and HR pathways. Pol θ may be considered as a novel target for lung cancer therapy.
Collapse
Affiliation(s)
- Chun-Hua Dai
- Department of Radiation Oncology, Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Ping Chen
- Department of Pulmonary Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Jian Li
- Department of Pulmonary Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Tin Lan
- Institute of Medical Science, Jiangsu University, Zhenjiang, China
| | - Yong-Chang Chen
- Institute of Medical Science, Jiangsu University, Zhenjiang, China
| | - Hai Qian
- Institute of Medical Science, Jiangsu University, Zhenjiang, China
| | - Kang Chen
- Department of Pulmonary Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Mei-Yu Li
- Department of Pulmonary Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang, China
| |
Collapse
|
5
|
Abstract
DNA polymerase theta (pol θ) is encoded in the genomes of many eukaryotes, though not in fungi. Pol θ is encoded by the POLQ gene in mammalian cells. The C-terminal third of the protein is a family A DNA polymerase with additional insertion elements relative to prokaryotic homologs. The N-terminal third is a helicase-like domain with DNA-dependent ATPase activity. Pol θ is important in the repair of genomic double-strand breaks (DSBs) from many sources. These include breaks formed by ionizing radiation and topoisomerase inhibitors, breaks arising at stalled DNA replication forks, breaks introduced during diversification steps of the mammalian immune system, and DSB induced by CRISPR-Cas9. Pol θ participates in a route of DSB repair termed "alternative end-joining" (altEJ). AltEJ is independent of the DNA binding Ku protein complex and requires DNA end resection. Pol θ is able to mediate joining of two resected 3' ends harboring DNA sequence microhomology. "Signatures" of Pol θ action during altEJ are the frequent utilization of longer microhomologies, and the insertion of additional sequences at joining sites. The mechanism of end-joining employs the ability of Pol θ to tightly grasp a 3' terminus through unique contacts in the active site, allowing extension from minimally paired primers. Pol θ is involved in controlling the frequency of chromosome translocations and preserves genome integrity by limiting large deletions. It may also play a backup role in DNA base excision repair. POLQ is a member of a cluster of similarly upregulated genes that are strongly correlated with poor clinical outcome for breast cancer, ovarian cancer and other cancer types. Inhibition of pol θ is a compelling approach for combination therapy of radiosensitization.
Collapse
Affiliation(s)
- Richard D Wood
- Department of Epigenetics & Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, P.O. Box 389, Smithville, TX 78957, USA; Graduate School of Biomedical Sciences at Houston, USA.
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, 89 Beaumont Ave, Burlington, VT 05405, USA.
| |
Collapse
|
6
|
Brandalize APC, Schüler-Faccini L, Hoffmann JS, Caleffi M, Cazaux C, Ashton-Prolla P. A DNA repair variant in POLQ (c.-1060A > G) is associated to hereditary breast cancer patients: a case-control study. BMC Cancer 2014; 14:850. [PMID: 25409685 PMCID: PMC4246548 DOI: 10.1186/1471-2407-14-850] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 11/07/2014] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND One of the hallmarks of cancer is the occurrence of high levels of chromosomal rearrangements as a result of inaccurate repair of double-strand breaks (DSB). Germline mutations in BRCA and RAD51 genes, involved in DSB repair, are strongly associated with hereditary breast cancer. Pol θ, a translesional DNA polymerase specialized in the replication of damaged DNA, has been also shown to contribute to DNA synthesis associated to DSB repair. It is noteworthy that POLQ is highly expressed in breast tumors and this expression is able to predict patient outcome. The objective of this study was to analyze genetic variants related to POLQ as new population biomarkers of risk in hereditary (HBC) and sporadic (SBC) breast cancer. METHODS We analyzed through case-control study nine SNPs of POLQ in hereditary (HBC) and sporadic (SBC) breast cancer patients using Taqman Real Time PCR assays. Polymorphisms were systematically identified through the NCBI database and are located within exons or promoter regions. We recruited 204 breast cancer patients (101 SBC and 103 HBC) and 212 unaffected controls residing in Southern Brazil. RESULTS The rs581553 SNP located in the promoter region was strongly associated with HBC (c.-1060A > G; HBC GG = 15, Control TT = 8; OR = 5.67, CI95% = 2.26-14.20; p < 0.0001). Interestingly, 11 of 15 homozygotes for this polymorphism fulfilled criteria for Hereditary Breast and Ovarian Cancer (HBOC) syndrome. Furthermore, 12 of them developed bilateral breast cancer and one had a familial history of bilateral breast cancer. This polymorphism was also associated with bilateral breast cancer in 67 patients (OR = 9.86, CI95% = 3.81-25.54). There was no statistically significant difference of age at breast cancer diagnosis between SNP carriers and non-carriers. CONCLUSIONS Considering that Pol θ is involved in DBS repair, our results suggest that this polymorphism may contribute to the etiology of HBC, particularly in patients with bilateral breast cancer.
Collapse
Affiliation(s)
- Ana Paula Carneiro Brandalize
- />Laboratory of Medical Genomics, Experimental Research Center, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
- />Laboratory of Genomics, Proteomics and DNA Repair, University of Caxias do Sul, Caxias do Sul, Brazil
- />Instituto Nacional de Genética Médica Populacional, INAGEMP, Porto Alegre, Brazil
| | - Lavínia Schüler-Faccini
- />Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
- />Instituto Nacional de Genética Médica Populacional, INAGEMP, Porto Alegre, Brazil
| | - Jean-Sébastien Hoffmann
- />Equipe « Labellisée Ligue contre le Cancer 2013 » INSERM Unit 1037; CNRS ERL 5294, CRCT (Cancer Research Center of Toulouse), Toulouse Oncopole, France
- />University of Toulouse; UPS, F-31077 Toulouse, France
| | | | - Christophe Cazaux
- />Equipe « Labellisée Ligue contre le Cancer 2013 » INSERM Unit 1037; CNRS ERL 5294, CRCT (Cancer Research Center of Toulouse), Toulouse Oncopole, France
- />University of Toulouse; UPS, F-31077 Toulouse, France
| | - Patricia Ashton-Prolla
- />Laboratory of Medical Genomics, Experimental Research Center, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
- />Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
- />Instituto Nacional de Genética Médica Populacional, INAGEMP, Porto Alegre, Brazil
| |
Collapse
|
7
|
Yousefzadeh MJ, Wyatt DW, Takata KI, Mu Y, Hensley SC, Tomida J, Bylund GO, Doublié S, Johansson E, Ramsden DA, McBride KM, Wood RD. Mechanism of suppression of chromosomal instability by DNA polymerase POLQ. PLoS Genet 2014; 10:e1004654. [PMID: 25275444 PMCID: PMC4183433 DOI: 10.1371/journal.pgen.1004654] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 08/05/2014] [Indexed: 12/13/2022] Open
Abstract
Although a defect in the DNA polymerase POLQ leads to ionizing radiation sensitivity in mammalian cells, the relevant enzymatic pathway has not been identified. Here we define the specific mechanism by which POLQ restricts harmful DNA instability. Our experiments show that Polq-null murine cells are selectively hypersensitive to DNA strand breaking agents, and that damage resistance requires the DNA polymerase activity of POLQ. Using a DNA break end joining assay in cells, we monitored repair of DNA ends with long 3' single-stranded overhangs. End joining events retaining much of the overhang were dependent on POLQ, and independent of Ku70. To analyze the repair function in more detail, we examined immunoglobulin class switch joining between DNA segments in antibody genes. POLQ participates in end joining of a DNA break during immunoglobulin class-switching, producing insertions of base pairs at the joins with homology to IgH switch-region sequences. Biochemical experiments with purified human POLQ protein revealed the mechanism generating the insertions during DNA end joining, relying on the unique ability of POLQ to extend DNA from minimally paired primers. DNA breaks at the IgH locus can sometimes join with breaks in Myc, creating a chromosome translocation. We found a marked increase in Myc/IgH translocations in Polq-defective mice, showing that POLQ suppresses genomic instability and genome rearrangements originating at DNA double-strand breaks. This work clearly defines a role and mechanism for mammalian POLQ in an alternative end joining pathway that suppresses the formation of chromosomal translocations. Our findings depart from the prevailing view that alternative end joining processes are generically translocation-prone.
Collapse
Affiliation(s)
- Matthew J. Yousefzadeh
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, United States of America
| | - David W. Wyatt
- Lineberger Comprehensive Cancer Center, Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Kei-ichi Takata
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, United States of America
| | - Yunxiang Mu
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
| | - Sean C. Hensley
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
| | - Junya Tomida
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, United States of America
| | - Göran O. Bylund
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, The University of Vermont, Burlington, Vermont
| | - Erik Johansson
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Dale A. Ramsden
- Lineberger Comprehensive Cancer Center, Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Kevin M. McBride
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, United States of America
| | - Richard D. Wood
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, United States of America
| |
Collapse
|
8
|
Yousefzadeh MJ, Wood RD. DNA polymerase POLQ and cellular defense against DNA damage. DNA Repair (Amst) 2013; 12:1-9. [PMID: 23219161 PMCID: PMC3534860 DOI: 10.1016/j.dnarep.2012.10.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 10/15/2012] [Indexed: 12/15/2022]
Abstract
In mammalian cells, POLQ (pol θ) is an unusual specialized DNA polymerase whose in vivo function is under active investigation. POLQ has been implicated by different experiments to play a role in resistance to ionizing radiation and defense against genomic instability, in base excision repair, and in immunological diversification. The protein is formed by an N-terminal helicase-like domain, a C-terminal DNA polymerase domain, and a large central domain that spans between the two. This arrangement is also found in the Drosophila Mus308 protein, which functions in resistance to DNA interstrand crosslinking agents. Homologs of POLQ and Mus308 are found in multicellular eukaryotes, including plants, but a comparison of phenotypes suggests that not all of these genes are functional orthologs. Flies defective in Mus308 are sensitive to DNA interstrand crosslinking agents, while mammalian cells defective in POLQ are primarily sensitive to DNA double-strand breaking agents. Cells from Polq(-/-) mice are hypersensitive to radiation and peripheral blood cells display increased spontaneous and ionizing radiation-induced levels of micronuclei (a hallmark of gross chromosomal aberrations), though mice apparently develop normally. Loss of POLQ in human and mouse cells causes sensitivity to ionizing radiation and other double strand breaking agents and increased DNA damage signaling. Retrospective studies of clinical samples show that higher levels of POLQ gene expression in breast and colorectal cancer are correlated with poorer outcomes for patients. A clear understanding of the mechanism of action and physiologic function of POLQ in the cell is likely to bear clinical relevance.
Collapse
Affiliation(s)
- Matthew J Yousefzadeh
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, P.O. Box 389, Smithville, TX 78957, USA
| | | |
Collapse
|