The enzymic initiation of repair of photoalkylated bases in DNA will be investigated. An endonuclease activity that breaks such DNA will be purified from human placenta, cultured human cells and from Micrococcus luteus. These enzymes will be characterized. Detailed physical and chemical analysis of the substrate will be done to determine the precise type of DNA deformity recognized by the enzyme. The endonucleases will be assayed by measuring conversion of damaged superhelical DNA to the nicked form. The activity in normal cells will be compared to that in xeroderma pigmentosum, ataxia telangectasia and Fanconi's anemia, genetically transmitted diseases with high incidences of cancer. Deficiencies will be explored by standard biochemical techniques, including enzyme purification. Photoalkylation of DNA results in additions of alkyl groups at the 8-carbon of purines, an alteration shared with some chemical carcinogens. The effects of ultraviolet - induced pyrimidine dimers on excision of uracil from the DNA of cultured human cells will be investigated. Unrepaired damage in DNA is mutagenic and carcinogenic. Therefore these results will elucidate the mechanisms of excision-repair of DNA damage in normal cells and the defective mechanisms of human diseases that lead to the development of cancer.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA024103-07A1
Application #
3166323
Study Section
Chemical Pathology Study Section (CPA)
Project Start
1978-09-30
Project End
1990-06-30
Budget Start
1987-07-01
Budget End
1988-06-30
Support Year
7
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Temple University
Department
Type
Schools of Medicine
DUNS #
City
Philadelphia
State
PA
Country
United States
Zip Code
19122
Ganguly, T; Duker, N J (1992) Inhibition of DNA polymerase activity by thymine hydrates. Mutat Res 293:71-7
Ganguly, T; Duker, N J (1991) Stability of DNA thymine hydrates. Nucleic Acids Res 19:3319-23
Duker, N J; Weems, K M (1990) Excision of cytosine hydrates from Z-DNA. Nucleic Acids Res 18:2007-10
Ganguly, T; Weems, K M; Duker, N J (1990) Ultraviolet-induced thymine hydrates in DNA are excised by bacterial and human DNA glycosylase activities. Biochemistry 29:7222-8
Gallagher, P E; Duker, N J (1989) Formation of purine photoproducts in a defined human DNA sequence. Photochem Photobiol 49:599-605
Gallagher, P E; Weiss, R B; Brent, T P et al. (1989) A human endonuclease incises ultraviolet-irradiated DNA at cytosines and oxidized DNA at thymines. Mol Carcinog 2:188-91
Weiss, R B; Duker, N J (1987) Endonucleolytic incision of UVB-irradiated DNA. Photochem Photobiol 45:763-8
Duker, N J; Gallagher, P E (1986) Detection of DNA damage in human cells and tissue using sequencing techniques. Exp Mol Pathol 44:117-31
Weiss, R B; Duker, N J (1986) Photoalkylated DNA and ultraviolet-irradiated DNA are incised at cytosines by endonuclease III. Nucleic Acids Res 14:6621-31
Duker, N J; Jensen, D E; Hart, D M (1985) Modifications of circular DNA by photoalkylation. Radiat Res 103:114-21