Microenvironmental factors such as hypoxia, nutrient availability, blood flow, and pH are important in determining the effects of chemotherapy and radiotherapy on malignant cells in solid tumors. In vitro, the environmental pH (pHe) and the intracellular pH (pHi) have been shown to influence cell proliferation and to modulate the response of cells to drugs. The overall goal of this project is to assess the role of microenvironmental heterogeneity in determining the efficacy of chemotherapy and to devise strategies which use the abnormal pH in solid tumors to improve the outcome of cancer therapy. The experiments proposed in this application will assess the interrelationship between pHe and pHi in vitro and the effects of pHe and pHi on the sensitivity of cells in vitro to cancer therapeutic agents (POR, cis-Pt). The majority of the proposed studies will be performed using EMT6 mouse mammary tumor cells in vitro. The pHi will be examined using interactive laser fluorescence cytometry. The effects of regional variations in pHo on the sensitivity of the cells to drugs will be assessed using measurements of cell survival (colony formation) and DNA damage (alkaline elution techniques). Pharmacological manipulation of the cellular mechanisms controlling pHi will be used to modulate the effects of drugs on EMT6 tumor cells. Finally, possible mechanisms by which pHe and pHi alter drug activity will be examined; these include alterations in drug uptake, the repair of drug-induced lesions, alterations in cell proliferation, and changes in drug activation. These studies may result in new information which will lead to the design of new drugs and/or combinations specifically formulated to attack those tumor cell subpopulations which are situated in microenvironments that render potentially sensitive cells resistant to standard cancer therapeutic agents.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA041239-04A2
Application #
3181521
Study Section
Experimental Therapeutics Subcommittee 1 (ET)
Project Start
1987-07-01
Project End
1995-11-30
Budget Start
1992-12-29
Budget End
1993-11-30
Support Year
4
Fiscal Year
1993
Total Cost
Indirect Cost
Name
George Washington University
Department
Type
Schools of Medicine
DUNS #
City
Washington
State
DC
Country
United States
Zip Code
20052
Lin, Z P; Boller, Y C; Amer, S M et al. (1998) Prevention of brefeldin A-induced resistance to teniposide by the proteasome inhibitor MG-132: involvement of NF-kappaB activation in drug resistance. Cancer Res 58:3059-65
Laurencot, C M; Kennedy, K A (1995) Influence of pH on the cytotoxicity of cisplatin in EMT6 mouse mammary tumor cells. Oncol Res 7:371-9
Laurencot, C M; Andrews, P A; Kennedy, K A (1995) Inhibitors of intracellular pH regulation induce cisplatin resistance in EMT6 mouse mammary tumor cells. Oncol Res 7:363-9
Rockwell, S; Hughes, C S; Keyes, S R et al. (1993) Porfiromycin as an adjunct to radiotherapy in young and old mice. Exp Gerontol 28:281-93
Rockwell, S; Sartorelli, A C; Tomasz, M et al. (1993) Cellular pharmacology of quinone bioreductive alkylating agents. Cancer Metastasis Rev 12:165-76
Keyes, S R; Rockwell, S; Kennedy, K A et al. (1991) Distribution of porfiromycin in EMT6 solid tumors and normal tissues of BALB/c mice. J Natl Cancer Inst 83:632-7
Rockwell, S; Hughes, C S; Kennedy, K A (1991) Effect of host age on microenvironmental heterogeneity and efficacy of combined modality therapy in solid tumors. Int J Radiat Oncol Biol Phys 20:259-63
Sostman, H D; Charles, H C; Rockwell, S et al. (1990) Soft-tissue sarcomas: detection of metabolic heterogeneity with P-31 MR spectroscopy. Radiology 176:837-43
Sostman, D; Rockwell, S; Smith, G J et al. (1988) Magnetic resonance, pathology and physiology of the BA1112 rhabdomyosarcoma in vivo. Invest Radiol 23:277-88