The long range objective of the proposed studies is the development of a new endocrine-based therapy for the treatment of human breast cancer. Our experiments will be performed with the hormone-responsive human breast cancer tissue culture cell line, MCF-7. The major hypothesis to be tested is that estradiol induction of human breast cancer growth is dependent upon calcium; therefore, calcium antagonism constitute a novel ode of human breast cancer endocrine therapy. Sp.
Aim 1 is to determine if calcium channel blockade by verapamil, nifedipine, calmodulin antagonism by W-7, W-13 or protein kinase C antagonism by H-7 are independent and novel mechanisms of antagonism of estrogen-induced breast cancer cell proliferation. Estrogen-induced proliferation will be monitored by induction of c-myc mRNA, 3H-thymidine incorporation, ad cell number. Sp.
Aim 2 is to determine the effects of calmodulin inhibitors, calcium channel blockers, and a protein kinase C inhibitor on MCF-7 estrogen receptor,levels and binding affinities, to determine if these drugs exert antiestrogen actions like tamoxifen by competing with estradiol for estrogen receptor binding sites. Sp.
Aim 3 is to monitor calcium ion fluxes in MCF-7 cells after exposure to estradiol using 45Ca and Fura-2 fluorescence changes to monitor changes in the free cytosolic calcium concentration [and investigate the mechanism of E2 and drug effects on Ca +2 fluxes through voltage-sensitive Ca +2 channels using voltage-patch clamp techniques.] Sp.
Aims 4 and 5 are to assess the effects of estradiol on calmodulin and protein kinase activities in MCF-7 cells and to demonstrate that the specific antiestrogenic activities of the various calmodulin and protein kinase C inhibitors are correlated with inhibition of these biochemical processes. [Particular emphasis is placed on in vivo and in vitro estradiol-stimulated protein phosphorylation in the membrane and cytosol fractions during the first 30 minutes of exposure to estradiol and whether estradiol effects on the calcium channel are mediated by phosphorylation of this channel.]

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA046350-02
Application #
3189602
Study Section
Experimental Therapeutics Subcommittee 1 (ET)
Project Start
1989-07-01
Project End
1992-06-30
Budget Start
1990-07-01
Budget End
1991-06-30
Support Year
2
Fiscal Year
1990
Total Cost
Indirect Cost
Name
West Virginia University
Department
Type
Schools of Dentistry
DUNS #
191510239
City
Morgantown
State
WV
Country
United States
Zip Code
26506
Strobl, J S; Wonderlin, W F; Flynn, D C (1995) Mitogenic signal transduction in human breast cancer cells. Gen Pharmacol 26:1643-9
Wonderlin, W F; Woodfork, K A; Strobl, J S (1995) Changes in membrane potential during the progression of MCF-7 human mammary tumor cells through the cell cycle. J Cell Physiol 165:177-85
Woodfork, K A; Wonderlin, W F; Peterson, V A et al. (1995) Inhibition of ATP-sensitive potassium channels causes reversible cell-cycle arrest of human breast cancer cells in tissue culture. J Cell Physiol 162:163-71
Strobl, J S; Peterson, V A; Woodfork, K A (1994) A survey of human breast cancer sensitivity to growth inhibition by calmodulin antagonists in tissue culture. Biochem Pharmacol 47:2157-61
Matamoros, M C; Van Dyke, K; Strobl, J S (1993) Regulation of rat growth hormone gene expression in tissue culture: influence of cell growth phase. Biochem Mol Biol Int 29:213-20
Strobl, J S; Peterson, V A (1992) Tamoxifen-resistant human breast cancer cell growth: inhibition by thioridazine, pimozide and the calmodulin antagonist, W-13. J Pharmacol Exp Ther 263:186-93
Strobl, J S; Kirkwood, K L; Lantz, T K et al. (1990) Inhibition of human breast cancer cell proliferation in tissue culture by the neuroleptic agents pimozide and thioridazine. Cancer Res 50:5399-405