Effect of estrogen, tamoxifen and epidermal growth factor on the transcriptional regulation of vascular endothelial growth factor in breast cancer cells.

BACKGROUND VEGF (Vascular Endothelial Growth Factor) is a key factor of angiogenesis and high tissue VEGF levels are related to a poor prognosis in breast cancer. MATERIALS AND METHODS By semi-quantitative RT-PCR, we determined the relative expressions of VEGF mRNA in MCF-7 (both ER-alpha+ and ER-beta+ (mainly ER-alpha+), PR+, bcl-2+, EGFR-) and MB-MDA-231 (only ER-beta+, PR-, EGFR-) breast cancer cells which were treated with estrogen, tamoxifen and EGF (Epidermal Growth Factor). RESULTS In MCF-7 cell lines, estrogen induced the expression of VEGF mRNA while tamoxifen reduced its expression. Estrogen and tamoxifen did not confer any significant effect on MB-MDA-231 cells and EGF showed no significant effect on MCF-7 or MB-MDA-231. CONCLUSION Reduced VEGF mRNA expression of MCF-7 cells treated with tamoxifen may be related to the antagonistic effect of tamoxifen on ER-positive breast cancer, and this antagonistic effect may be related to ER-alpha.