Agents targeting topoisomerase I or II are active against a wide range of human tumors. Stabilization of covalent complexes, converting topoisomerases into DNA damage, is an essential aspect of cell killing by these drugs. Genetic experiments have demonstrated that enzymes that participate in the excision repair pathway are capable of interacting with the covalent complexes formed by either topoisomerase I or II. Unexpectedly, mutations in excision repair genes lead to partial resistance to topoisomerase agents, suggesting that processing of covalent complexes is related to the cytotoxicity of topoisomerase targeting drugs. The experiments in this grant will examine the consequences of mutations in various DNA repair pathways to determine how DNA repair pathways process topoisomerase-mediated DNA damage. Biochemical experiments will test which components of the excision repair machinery recognize and process topoisomerase-mediated DNA damage. Genetic approaches will be used to identify other DNA repair enzymes that influence cell killing by anti-topoisomerase agents. The processing of topoisomerase:DNA covalent complexes by DNA repair proteins may also play a role in the other cellular effects of topoisomerase targeting drugs. Recent evidence has demonstrated that etoposide and other topoisomerase II-targeting drugs can cause secondary malignancies by generating translocations that cause the overexpression and activation of proto-oncogenes. Since camptothecins also generate high levels of recombination, topoisomerase I targeting drugs may also lead to significant levels of secondary malignancies. A major aim of this project is will be to apply a yeast model system to study how DNA repair functions influence the type and frequency of genetic aberrations caused by drugs targeting topoisomerases I or H. These experiments will provide information concerning how topoisomerase inhibitors exert their cytotoxic effects against cancer cells, and how cancer cells may develop resistance to these agents. The experiments will also be important for understanding how topoisomerase targeting drugs lead to secondary malignancies.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA082313-03
Application #
6377330
Study Section
Experimental Therapeutics Subcommittee 1 (ET)
Program Officer
Warner, Huber
Project Start
1999-07-02
Project End
2004-04-30
Budget Start
2001-05-01
Budget End
2002-04-30
Support Year
3
Fiscal Year
2001
Total Cost
$230,460
Indirect Cost
Name
St. Jude Children's Research Hospital
Department
Type
DUNS #
067717892
City
Memphis
State
TN
Country
United States
Zip Code
38105
Katyal, Sachin; Lee, Youngsoo; Nitiss, Karin C et al. (2014) Aberrant topoisomerase-1 DNA lesions are pathogenic in neurodegenerative genome instability syndromes. Nat Neurosci 17:813-21
Hasinoff, Brian B; Wu, Xing; Nitiss, John L et al. (2012) The anticancer multi-kinase inhibitor dovitinib also targets topoisomerase I and topoisomerase II. Biochem Pharmacol 84:1617-26
Nitiss, John L; Soans, Eroica; Rogojina, Anna et al. (2012) Topoisomerase assays. Curr Protoc Pharmacol Chapter 3:Unit 3.3.
Bahmed, Karim; Seth, Aman; Nitiss, Karin C et al. (2011) End-processing during non-homologous end-joining: a role for exonuclease 1. Nucleic Acids Res 39:970-8
Bahmed, Karim; Nitiss, Karin C; Nitiss, John L (2010) Yeast Tdp1 regulates the fidelity of nonhomologous end joining. Proc Natl Acad Sci U S A 107:4057-62
Nitiss, John L (2009) Targeting DNA topoisomerase II in cancer chemotherapy. Nat Rev Cancer 9:338-50
Nitiss, John L (2009) DNA topoisomerase II and its growing repertoire of biological functions. Nat Rev Cancer 9:327-37
Rogojina, Anna T; Nitiss, John L (2008) Isolation and characterization of mAMSA-hypersensitive mutants. Cytotoxicity of Top2 covalent complexes containing DNA single strand breaks. J Biol Chem 283:29239-50
Stepanov, Alexander; Nitiss, Karin C; Neale, Geoffrey et al. (2008) Enhancing drug accumulation in Saccharomyces cerevisiae by repression of pleiotropic drug resistance genes with chimeric transcription repressors. Mol Pharmacol 74:423-31
He, Xiaoping; van Waardenburg, Robert C A M; Babaoglu, Kerim et al. (2007) Mutation of a conserved active site residue converts tyrosyl-DNA phosphodiesterase I into a DNA topoisomerase I-dependent poison. J Mol Biol 372:1070-81

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