In the absence of successful new therapies for testing cancer understanding the mechanism of action of existing anticancer drugs holds the greatest promise for improving therapy and developing more selective anticancer drugs. Quinones form the largest and most active class of currently approved anticancer agents. Despite extensive study the mechanism of action of the antitumor quinones has not been elucidated. Two features are, however, clearly required for antitumor quinone activity, reductive metabolism and the formation of an alkylating species. The group of enzymes responsible for reductive metabolism of the antitumor quinones is the flavoenzymes. Our hypothesis is that key flavoenzymes both determine the extent of antitumor quinone bioactivation and can themselves be critical targets for quinone cytotoxicity. The Two mechanisms represent different aspects of the same process involving the formation of a reactive quinone species at the active site of the flavoenzyme. If the reactive species diffuses away it will affect other sensitive sites in the cell, but if it is trapped at the active site it will inhibit the enzyme. Our studies are focused on thioredoxin reductase (TR), a key flavoenzyme for ribonucleotide reductase, the first unique step in DNA synthesis and NAD(P)H:(quinone acceptor)oxidoreductase (DT- diaphorase, DT) a flavoenzyme that uniquely catalyzes the two electron reduction of quinones. We have evidence that antitumor quinones are suicide substrate inhibitors of TR and that inhibition of TR is related to quinone cytotoxicity. We also report that DT is present at very high levels in human tumors compared to normal tissue, but these high tumor levels are completely suppressed in smokers. This may affect the response of smokers to chemotherapy. The objectives of the study are: a) to measure DT an TR levels in human tissues and in cell culture models for smoking, and to relate the levels to response to cytotoxic quinones, and b) to conduct mechanistic studies of quinone bioactivation and flavoenzyme inhibition as a mechanism for the action of antitumor quinones. Our goal is to improve the treatment of cancer by understanding how antitumor quinone drugs work and to identify new molecular targets for the development of new drugs.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA048725-02
Application #
3192661
Study Section
Experimental Therapeutics Subcommittee 1 (ET)
Project Start
1990-08-01
Project End
1992-02-01
Budget Start
1991-08-01
Budget End
1992-02-01
Support Year
2
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
City
Rochester
State
MN
Country
United States
Zip Code
55905
Ihle, Nathan T; Williams, Ryan; Chow, Sherry et al. (2004) Molecular pharmacology and antitumor activity of PX-866, a novel inhibitor of phosphoinositide-3-kinase signaling. Mol Cancer Ther 3:763-72
Meuillet, Emmanuelle J; Mahadevan, Daruka; Vankayalapati, Hariprasad et al. (2003) Specific inhibition of the Akt1 pleckstrin homology domain by D-3-deoxy-phosphatidyl-myo-inositol analogues. Mol Cancer Ther 2:389-99
Husbeck, B; Berggren, M I; Powis, G (2001) DNA microarray reveals increased expression of thioredoxin peroxidase in thioredoxin-1 transfected cells and its functional consequences. Adv Exp Med Biol 500:157-68
Powis, G; Montfort, W R (2001) Properties and biological activities of thioredoxins. Annu Rev Biophys Biomol Struct 30:421-55
Kakolyris, S; Giatromanolaki, A; Koukourakis, M et al. (2001) Thioredoxin expression is associated with lymph node status and prognosis in early operable non-small cell lung cancer. Clin Cancer Res 7:3087-91
Powis, G; Montfort, W R (2001) Properties and biological activities of thioredoxins. Annu Rev Pharmacol Toxicol 41:261-95
Berggren, M M; Powis, G (2001) Alternative splicing is associated with decreased expression of the redox proto-oncogene thioredoxin-1 in human cancers. Arch Biochem Biophys 389:144-9
Berggren, M I; Husbeck, B; Samulitis, B et al. (2001) Thioredoxin peroxidase-1 (peroxiredoxin-1) is increased in thioredoxin-1 transfected cells and results in enhanced protection against apoptosis caused by hydrogen peroxide but not by other agents including dexamethasone, etoposide, and doxorubicin. Arch Biochem Biophys 392:103-9
Baker, A; Santos, B D; Powis, G (2000) Redox control of caspase-3 activity by thioredoxin and other reduced proteins. Biochem Biophys Res Commun 268:78-81
Freemerman, A J; Powis, G (2000) A redox-inactive thioredoxin reduces growth and enhances apoptosis in WEHI7.2 cells. Biochem Biophys Res Commun 274:136-41

Showing the most recent 10 out of 44 publications