We propose to continue our investigations of four specific areas which relate to hypoxia in tumors. Three deal with overcoming the problem of the radioresistance of hypoxic cells in tumors, the fourth with exploiting hypoxia to achieve tumor-specific sensitization to chemotherapy and radiation. The four projects are: (1) In-depth studies of new radiosensitizers and other means of improving upon misonidazole (MIS) and its less toxic analog SR-2508. Included in this will be studies of depletion of glutathione (GSH) in vivo, and enhancement of sensitizer uptake by mild hyperthermia. (2) Studies of the possibility of enhancing hypoxic cell toxicity in tumors in vivo at clinical levels of radiosensitizers by depletion of intracellular GSH. (3) Investigations of acute and chronic hypoxia in a variety of experimental tumors including changing hematocrit levels and blood flow to improve tumor oxygenation. (4) Studies of the """"""""preincubation"""""""" effect by which treatment of hypoxic cells with radiosensitizers renders them more sensitive to subsequent exposure to chemotherapeutic drugs and radiation. This will include a study of the mechanism of the enhancement of melphalan-induced DNA crosslinks, and the mechanism of the removal of the shoulder of the X-ray survival curve by pretreatment of cells to MIS. We will also investigate with CHO cells in vitro the potential clinical use of this shoulder removal, by determining whether it occurs in aerobic cells adjacent to hypoxic cells, whether it occurs at clinical doses and exposure times and whether it can be enhanced by GSH depletion, and finally, whether it occurs in tumors in vivo. If it can be produced in human tumors it would substantially increase their response to conventional radiotherapy. Four tumors will be used: the EMT-6, KHT and RIF-1 sarcomas and the SCC VII carcinoma. All will be assayed initially by in vivo-in vitro excision, and some by the regrowth delay and TCD50 assays. In Project 3 the effect of hematocrit and blood flow changes on the radiation response of out, skin and spermatagonia will also be tested. The mechanism studies in Project 4 will involve measurements of DNA strand-break and crosslink formation and repair using the alkaline elution assay.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA015201-14
Application #
3164128
Study Section
Radiation Study Section (RAD)
Project Start
1978-12-01
Project End
1988-11-30
Budget Start
1986-12-01
Budget End
1987-11-30
Support Year
14
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Stanford University
Department
Type
Schools of Medicine
DUNS #
800771545
City
Stanford
State
CA
Country
United States
Zip Code
94305
Brown, Martin (2010) Henry S. Kaplan Distinguished Scientist Award Lecture 2007. The remarkable yin and yang of tumour hypoxia. Int J Radiat Biol 86:907-17
Brown, J Martin (2002) Tumor microenvironment and the response to anticancer therapy. Cancer Biol Ther 1:453-8
Peters, Katherine B; Brown, J Martin (2002) Tirapazamine: a hypoxia-activated topoisomerase II poison. Cancer Res 62:5248-53
Birrell, Geoff W; Brown, James A; Wu, H Irene et al. (2002) Transcriptional response of Saccharomyces cerevisiae to DNA-damaging agents does not identify the genes that protect against these agents. Proc Natl Acad Sci U S A 99:8778-83
Delahoussaye, Y M; Evans, J W; Brown, J M (2001) Metabolism of tirapazamine by multiple reductases in the nucleus. Biochem Pharmacol 62:1201-9
Birrell, G W; Giaever, G; Chu, A M et al. (2001) A genome-wide screen in Saccharomyces cerevisiae for genes affecting UV radiation sensitivity. Proc Natl Acad Sci U S A 98:12608-13
Brown, J M (2001) Therapeutic targets in radiotherapy. Int J Radiat Oncol Biol Phys 49:319-26
Peters, K B; Wang, H; Brown, J M et al. (2001) Inhibition of DNA replication by tirapazamine. Cancer Res 61:5425-31
Wouters, B G; Delahoussaye, Y M; Evans, J W et al. (2001) Mitochondrial dysfunction after aerobic exposure to the hypoxic cytotoxin tirapazamine. Cancer Res 61:145-52
Bernhard, E J; Mitchell, J B; Deen, D et al. (2000) Re-evaluating gadolinium(III) texaphyrin as a radiosensitizing agent. Cancer Res 60:86-91

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