Our goal is to characterize the mutation spectra and identify potential molecular markers of low-linear energy transfer (LET) radiations (gamma-rays) and high-LET radiations (neutrons). Ionizing radiations are known to generate many kinds of DNA lesions as a result of damages to sugars, bases and sugar-phosphate backbone of DNA molecules. The lesions and processes that underlie mutation and cancer, however, remain unknown. We hypothesize that ionizing radiations will induce a wide spectrum of mutations including point mutations, deletions of various sizes and complex rearrangements and that the spectrum will be a function of radiation dose, dose-rate and quality. This hypothesis can be tested comprehensively using our newly developed polymerase chain reaction (PCR)-based procedure coupled with conventional Southern blot hybridization and molecular cytogenetic procedures to characterize mutants induced by 60-Co gamma-rays and by fission-spectrum neutrons. These procedures are capable of detecting a full range of molecular events associated with mutation. Using the unique radiation facilities at Argonne National Laboratory, capable of irradiating cells at very low dose rates, mutations will be analyzed in the Chinese hamster ovary cells(clone Kl-BH4)/hypoxanthine-guanine phosphoribosyltransferase (CHO/PRT) assay. The CHO/HPRT assay was chosen because it has been well characterized at the cellular and molecular level and we have developed a large cellular mutagenesis database for low- and high-LET radiations. Further, our PCR procedure is capable of detecting a wide spectrum of mutations in a large number of mutants. Our proposed research has three specific aims: (1) to study the effects of the dose and dose rate on gamma-ray-induced mutation spectra; (2) to determine the influence of dose and dose rate on neutron-induced mutation spectra and compare it to the gamma-ray spectra; (3) to investigate the role of DNA repair in radiation mutagenesis by studying the modulation of the mutation spectra induced by gamma-rays and by neutrons in a CHO-K1 cell derivative xrs-5, which is defective in DNA double-strand break rejoining ability.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA056434-03
Application #
2097309
Study Section
Special Emphasis Panel (SRC (40))
Project Start
1992-06-01
Project End
1996-05-31
Budget Start
1994-07-26
Budget End
1995-05-31
Support Year
3
Fiscal Year
1994
Total Cost
Indirect Cost
Name
University of Texas Medical Br Galveston
Department
Public Health & Prev Medicine
Type
Schools of Medicine
DUNS #
041367053
City
Galveston
State
TX
Country
United States
Zip Code
77555
Schwartz, J L; Jordan, R; Sun, J et al. (2000) Dose-dependent changes in the spectrum of mutations induced by ionizing radiation. Radiat Res 153:312-7
An, J; Trieff, N M; Hsie, A W (1998) PCR-directed DNA sequencing of ""nondeletion"" HPRT-mutants induced by bleomycin in CHO K1-BH4 cells. Environ Mol Mutagen 32:244-50
Schwartz, J L; Hsie, A W (1997) Genetic and cytogenetic markers of exposure to high-linear energy transfer radiation. Radiat Res 148:S87-92
Hsie, A W; Porter, R C; Xu, Z et al. (1996) Molecular markers of ionizing radiation-induced gene mutations in mammalian cells. Environ Health Perspect 104 Suppl 3:675-8
Schwartz, J L; Porter, R C; Hsie, A W (1996) The molecular nature of spontaneous mutations at the hprt locus in the radiosensitive CHO mutant xrs-5. Mutat Res 351:53-60
Xu, Z; Yu, Y; Schwartz, J L et al. (1995) Molecular nature of spontaneous mutations at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus in Chinese hamster ovary cells. Environ Mol Mutagen 26:127-38
An, J; Hsie, A W (1994) Polymerase chain reaction-directed DNA sequencing of bleomycin-induced ""nondeletion""-type, 6-thioguanine-resistant mutants in Chinese hamster ovary cell derivative AS52: effects of an inhibitor and a mimic of superoxide dismutase. Environ Mol Mutagen 23:101-9
Yu, Y; Xu, Z; Hsie, A W (1994) Adriamycin induces large deletions as a major type of mutation in CHO cells. Mutat Res 325:91-8
Schwartz, J L; Rotmensch, J; Sun, J et al. (1994) Multiplex polymerase chain reaction-based deletion analysis of spontaneous, gamma ray- and alpha-induced hprt mutants of CHO-K1 cells. Mutagenesis 9:537-40