Author(s)

Alvin J. O. Almodovar¹, Xiang Zhu¹, Sally A. Litherland¹, David A. Decker^1,2*

¹Florida Hospital Cancer Institute, Research & Development Division, Orlando, FL, USA.
²University of Central Florida, College of Medicine, Orlando, FL, USA.

Promestriene (3-propyl ethyl, 17B-methyl estradiol) is a synthetic estrogen analogue with reported minimal systemic absorption which has been suggested for topical treatment of vaginal atrophy. Promestriene’s ability to stimulate proliferation and estrogen responsive gene expression was analyzed in estrogen receptor (ER+) positive breast cancer cell lines MCF-7, T-47D, and BT-474 using CFSE flow cytometric analysis, and quantitative RT-PCR analysis of GREB1 RNA expression, an estrogen responsive gene involved in estrogen receptor alpha expression. In estrogen replete conditions, Promestriene did not stimulate proliferation even at high concentrations (100,000 pg/ml). However, anti-estradiol depletion allowed low dose Promestriene (2 - 10 pg/ml) to stimulate GREB1 expression in all three cell lines at levels equal to that induced by estradiol (BT-474) or significantly higher than estradiol (MCF7 and T-47D). These findings suggest that Promestriene has the potential to support estrogen like cell signaling, a possible contraindication for use in treatment of vaginal atrophy associated with breast cancer aromatase inhibitor therapy.

Breast Cancer, Survivor, Estrogen Receptor Positive, Hormone Therapy, Side Effects, Promestriene

Almodovar, A. , Zhu, X. , Litherland, S. and Decker, D. (2015) Promestriene Affects GREB1 Expression in Estrogen Sensitive Breast Cancer Cells. Journal of Cancer Therapy, 6, 767-772. doi: 10.4236/jct.2015.69084.