The overall objective of this proposal is to determine the combined effect(s) of hyperthermia (40 to 48 degree) and radiation (0 to 100 Gy) exposure on DNA replication in mammalian cells, and the role of lesions in DNA replication in heat-, or combined heat and radiation-induced S phase cell cytotoxicity. The capacity of heated and/or irradiated S phase cells: to redistribute DNA being polymerized at the nuclear matrix into bulk DNA, to process this nascent DNA into higher- order (solenoid) chromatin structure, and ultimately to ligate this DNA fully into chromosome-sized DNA will be determined. The model we will test in heated cells is that long-term damage to the nuclear matrix, or its associated structures or macromolecules, results in residual lesions in DNA being replicated during hyperthermic exposure. A similar model will be tested to determine whether S phase cell sensitivity in the radiation sensitive ataxia telangiectasia human cells, the xrs CHO double strand break repair mutants or """"""""wild-type"""""""" cells exposed caffeine during X irradiation results from the failure of these cells to ligate replicating DNA fully into chromosomes. The nuclear alterations being examined in heated cells are the thermal denaturation of nuclear matrix protein(s), the precipitation of nuclear protein and RNA onto the nuclear matrix and the potentially irreversible association of the topoisomerase enzymes onto DNA adjacent to the nuclear matrix. We will determine whether these lesions in the DNA replicative process in heated cells result in the long-term presence of DNA strand breaks in DNA replicated during cell heating and thus ultimately to chromosome aberration formation and cytotoxicity.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA025957-09
Application #
3167102
Study Section
Radiation Study Section (RAD)
Project Start
1983-08-01
Project End
1993-05-31
Budget Start
1988-08-01
Budget End
1989-05-31
Support Year
9
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Utah
Department
Type
Schools of Medicine
DUNS #
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
Warters, R L; Barrows, L R; Chen, D J (1995) DNA double-strand break repair in two radiation-sensitive mouse mammary carcinoma cell lines. Mutat Res 336:1-7
Warters, R L; Barrows, L R (1994) Heat sensitivity of HeLa S3 cell DNA topoisomerase II. J Cell Physiol 159:468-74
Warters, R L; Chu, G L; Wong, R S et al. (1993) Nuclear protein redistribution in heat-shocked cells. J Cell Physiol 154:402-9
Warters, R L; Lyons, B W; Chen, D J et al. (1993) DNA-damage processing in a radiation-sensitive mouse cell line. Mutat Res 293:91-8
Warters, R L (1993) Persistence of radiation-induced double-strand breaks in the DNA of heated CHO cells. Int J Radiat Biol 64:669-76
Warters, R L; Lyons, B W (1992) Variation in radiation-induced formation of DNA double-strand breaks as a function of chromatin structure. Radiat Res 130:309-18
Warters, R L; Lyons, B W (1990) Inhibition of replicon cluster ligation into chromosomal DNA at elevated temperatures. J Cell Physiol 142:365-71
Warters, R L; Lyons, B W (1990) Detection of ionizing radiation-induced DNA double-strand breaks by filter elution is affected by nuclear chromatin structure. Radiat Res 124:309-16
Warters, R L; Lyons, B W; Kennedy, K et al. (1989) Topoisomerase activity in irradiated mammalian cells. Mutat Res 216:43-55
Warters, R L (1988) Hyperthermia blocks DNA processing at the nuclear matrix. Radiat Res 115:258-72

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