Treatment of human tumors with ionizing radiation has been an effective treatment of cancer for over 50 years. However, the continued limitation of this therapy is the inherent radiation resistance of some tumor types compared with others. The molecular basis of this difference in resistance is unknown. Throughout evolution, organisms have evolved a conserved mechanism of resistance. Induction of DNA damage signals a surveillance mechanism which arrests cells in the G2 phase of the cell cycle before entering mitosis where residual DNA breaks result in chromosome aberrations. During arrest in G2, DNA breaks are repaired and when repair is completed, the cells resume cycling. Two of the genes, Rad9 and Mec1, which control this arrest have been isolated in the budding yeast S. cerevisiae. This group of genes has been named checkpoints. We propose to isolate human homologues of these checkpoint genes and study their role radiation resistance. A simple genetic strategy has been developed to select for inhuman clones able to complement mutations in the yeast checkpoint genes. Human cDNAs which are obtained will be expressed in radiosensitive mammalian cell lines and increases in resistance determined. A survey of expression at the RNA and protein level in clinical specimens from categories of radiation sensitive and resistant tumors will be undertaken. In addition, a method to select for cDNA clones which interfere with Rad9 function in yeast has been developed. The selection will be used onto screen mutagenized Rad9 cDNAs and human cDNA libraries for dominant negative clones of Rad9. These clones will be expressed in mammalian cells and increases in radiation sensitivity monitored. cDNAs which can decrease the radiation resistance of tumors would be an unique resource and have potential clinical benefit in the future.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
1R01CA058954-01
Application #
3203050
Study Section
Special Emphasis Panel (SRC (56))
Project Start
1992-09-30
Project End
1995-09-29
Budget Start
1992-09-30
Budget End
1993-09-29
Support Year
1
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Washington
Department
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195
Schwartz, J L; Jordan, R; Kaufmann, W K et al. (2000) Evidence for the expression of radiation-induced potentially lethal damage being a p53-dependent process. Int J Radiat Biol 76:1037-43
Schwartz, J L; Russell, K J (1999) The effect of functional inactivation of TP53 by HPV-E6 transformation on the induction of chromosome aberrations by gamma rays in human tumor cells. Radiat Res 151:385-90
Schwartz, J L; Rasey, J; Wiens, L et al. (1999) Functional inactivation of p53 by HPV-E6 transformation is associated with a reduced expression of radiation-induced potentially lethal damage. Int J Radiat Biol 75:285-91
Banker, D E; Groudine, M; Norwood, T et al. (1997) Measurement of spontaneous and therapeutic agent-induced apoptosis with BCL-2 protein expression in acute myeloid leukemia. Blood 89:243-55
Patel, B K; Ray, S; Whiteside, T L et al. (1997) Correlation of constitutive activation of raf-1 with morphological transformation and abrogation of tyrosine phosphorylation of distinct sets of proteins in human squamous carcinoma cells. Mol Carcinog 18:1-6
Pati, D; Keller, C; Groudine, M et al. (1997) Reconstitution of a MEC1-independent checkpoint in yeast by expression of a novel human fork head cDNA. Mol Cell Biol 17:3037-46
Russell, K J; Wiens, L W; Demers, G W et al. (1996) Preferential radiosensitization of G1 checkpoint-deficient cells by methylxanthines. Int J Radiat Oncol Biol Phys 36:1099-106
Field, L L; Tobias, R; Thomson, G et al. (1996) Susceptibility to insulin-dependent diabetes mellitus maps to a locus (IDDM11) on human chromosome 14q24.3-q31. Genomics 33:1-8
Russell, K J; Wiens, L W; Demers, G W et al. (1995) Abrogation of the G2 checkpoint results in differential radiosensitization of G1 checkpoint-deficient and G1 checkpoint-competent cells. Cancer Res 55:1639-42