Several cancer chemotherapeutic agents, including radiomimetic drugs and topoisomerase inhibitors induce specific types of terminally blocked DNA double-strand breaks, and these lesions have been implicated in both cytotoxic and mutagenic effects of these compounds. In addition, the radiomimetic compounds, like ionizing radiation itself, induce a global genomic instability in a fraction of the progeny of treated cells. The first major goal of the proposed studies is to determine the stringency and the nature of an apparent linkage between specific double-strand break misrepair events and the acquisition of genomic instability. Toward this end, genomic instability, as judged by chromosome rearrangements as well as other criteria, will be quantitatively assessed in various classes of mutants induced in CHO cells by the radiomimetic agents bleomycin and neocarzinostatin, and by the topoisomerase II inhibitor amsacrine. The second major goal of the studies is to determine the possible role of DNA-PK in the repair of double-strand breaks induced by these three agents, with particular emphasis on whether DNA-PK play an active role in enforcing the fidelity of the repair. To this end, mutations induced by bleomycin in CHO cell sublines deficient in this kinase will be compared to existing mutants generated in parental CHO cells, mutants which apparently arise by inaccurate end-joining of double-strand breaks. Repair by end-joining will also be examined in vitro, using a system based on Xenopus egg extracts and synthetic substrates bearing defined, chemically modified DNA ends, again with emphasis on defining the biochemical role of DNA-PK in the end-joining process, particularly as it relates to repair fidelity. The relationship between double- strand break repair, repair fidelity, and acquired genomic instability should have important implications for the overall response of normal and tumor cells to double-strand cleaving agents, and may in the long term aid in efforts to manipulate cellular responses so as to increase the efficacy and reduce the carcinogenicity of these agents.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA040615-16
Application #
6172041
Study Section
Chemical Pathology Study Section (CPA)
Program Officer
Forry, Suzanne L
Project Start
1985-08-01
Project End
2003-05-31
Budget Start
2000-06-01
Budget End
2001-05-31
Support Year
16
Fiscal Year
2000
Total Cost
$189,773
Indirect Cost
Name
Virginia Commonwealth University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
City
Richmond
State
VA
Country
United States
Zip Code
23298
Chalasani, Sri Lakshmi; Kawale, Ajinkya S; Akopiants, Konstantin et al. (2018) Persistent 3'-phosphate termini and increased cytotoxicity of radiomimetic DNA double-strand breaks in cells lacking polynucleotide kinase/phosphatase despite presence of an alternative 3'-phosphatase. DNA Repair (Amst) 68:12-24
Menon, Vijay; Povirk, Lawrence F (2016) End-processing nucleases and phosphodiesterases: An elite supporting cast for the non-homologous end joining pathway of DNA double-strand break repair. DNA Repair (Amst) 43:57-68
Alotaibi, Moureq; Sharma, Khushboo; Saleh, Tareq et al. (2016) Radiosensitization by PARP Inhibition in DNA Repair Proficient and Deficient Tumor Cells: Proliferative Recovery in Senescent Cells. Radiat Res 185:229-45
Gewirtz, David A; Alotaibi, Moureq; Yakovlev, Vasily A et al. (2016) Tumor Cell Recovery from Senescence Induced by Radiation with PARP Inhibition. Radiat Res 186:327-332
Almohaini, Mohammed; Chalasani, Sri Lakshmi; Bafail, Duaa et al. (2016) Nonhomologous end joining of complex DNA double-strand breaks with proximal thymine glycol and interplay with base excision repair. DNA Repair (Amst) 41:16-26
Beckta, Jason M; Dever, Seth M; Gnawali, Nisha et al. (2015) Mutation of the BRCA1 SQ-cluster results in aberrant mitosis, reduced homologous recombination, and a compensatory increase in non-homologous end joining. Oncotarget 6:27674-87
Menon, Vijay; Povirk, Lawrence (2014) Involvement of p53 in the repair of DNA double strand breaks: multifaceted Roles of p53 in homologous recombination repair (HRR) and non-homologous end joining (NHEJ). Subcell Biochem 85:321-36
Akopiants, Konstantin; Mohapatra, Susovan; Menon, Vijay et al. (2014) Tracking the processing of damaged DNA double-strand break ends by ligation-mediated PCR: increased persistence of 3'-phosphoglycolate termini in SCAN1 cells. Nucleic Acids Res 42:3125-37
Mohapatra, Susovan; Yannone, Steven M; Lee, Suk-Hee et al. (2013) Trimming of damaged 3' overhangs of DNA double-strand breaks by the Metnase and Artemis endonucleases. DNA Repair (Amst) 12:422-32
Menon, Vijay R; Peterson, Erica J; Valerie, Kristoffer et al. (2013) Ligand modulation of a dinuclear platinum compound leads to mechanistic differences in cell cycle progression and arrest. Biochem Pharmacol 86:1708-20

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