We propose a combined basic and clinical investigation on the contribution of reactive oxygen species (ROS) to DNA damage, mutations and cancer. We hypothesize that an important source of the multiple mutations found in cancer cells is the extensive ROS-induced damage generated by endogenous processes and by numerous environmental agents. We have established new approaches for quantitating ROS-induced DNA damage and mutations. Firstly, we have evolved RNA molecules that bind with high affinity and specificity to the well characterized ROS-generated lesion in DNA, 8-oxo-deoxyguanosine. Secondly, we have established an assay for frameshift mutations in repetitive nucleotide (microsatellite) sequences, which we find to be preferentially damaged by ROS. We will use these approaches to study human cells exposed to agents that induce ROS and to conditions that alter proliferation, such as might occur during tumor growth and invasion. In addition, we will analyze breast and prostatic adenocarcinoma cells for microsatellite instability and for ROS-induced DNA damage. The RNA binders will allow us to study the heterogeneity of DNA damage in histological and cytological preparations of tumors. By the time a tumor is detected, it contains multiple mutations, some of which may be required for growth, invasion and metastasis. Delaying the rate of accumulation of mutations provides a new approach for the prevention of cancer deaths. Our goal is to determine if oxygen-induced DNA damage is a significant contributor to the multiple mutations that occur during tumorigenesis. If so, we might be able to diminish the levels of ROS in cells and thus slow the rate of tumor progression. Even a modest, 2-fold, decrease could increase the latent period before disease is manifested clinically and thus reduce cancer mortality.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
1R01CA080993-01
Application #
2826904
Study Section
Chemical Pathology Study Section (CPA)
Program Officer
Okano, Paul
Project Start
1999-07-06
Project End
2004-04-30
Budget Start
1999-07-06
Budget End
2000-04-30
Support Year
1
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of Washington
Department
Pathology
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195
Camps, Manel; Loeb, Lawrence A (2005) Critical role of R-loops in processing replication blocks. Front Biosci 10:689-98
Guo, Haiwei H; Choe, Juno; Loeb, Lawrence A (2004) Protein tolerance to random amino acid change. Proc Natl Acad Sci U S A 101:9205-10
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Bobola, Michael S; Emond, Mary J; Blank, A et al. (2004) Apurinic endonuclease activity in adult gliomas and time to tumor progression after alkylating agent-based chemotherapy and after radiotherapy. Clin Cancer Res 10:7875-83
Shen, Jiang-Cheng; Loeb, Lawrence A (2003) Mutations in the alpha8 loop of human APE1 alter binding and cleavage of DNA containing an abasic site. J Biol Chem 278:46994-7001
Davidson, John F; Fox, Richard; Harris, Dawn D et al. (2003) Insertion of the T3 DNA polymerase thioredoxin binding domain enhances the processivity and fidelity of Taq DNA polymerase. Nucleic Acids Res 31:4702-9
Silber, John R; Bobola, Michael S; Blank, A et al. (2002) The apurinic/apyrimidinic endonuclease activity of Ape1/Ref-1 contributes to human glioma cell resistance to alkylating agents and is elevated by oxidative stress. Clin Cancer Res 8:3008-18
Davidson, John F; Guo, Haiwei H; Loeb, Lawrence A (2002) Endogenous mutagenesis and cancer. Mutat Res 509:17-21
Loeb, L A (2001) A mutator phenotype in cancer. Cancer Res 61:3230-9
Jackson, A L; Loeb, L A (2001) The contribution of endogenous sources of DNA damage to the multiple mutations in cancer. Mutat Res 477:7-21

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