The Effects of Black Cohosh (BC) on Progesterone Receptor (PR) and BRCA1 in T-47D Breast Cancer Cells

Presentation Number: FRI 125
Date of Presentation: April 1st, 2016

Kelly Marie Hallman*1, Katie Marie Aleck1, Brigitte Dwyer1, Tonya Darghali2, Meghan Quigley1 and Sumi Dinda1
1Oakland University, Rochester, MI, 2Oakland University

Abstract

Black cohosh (BC), isolated from the rhizomes of the North American plant Cimicifuga Racemosa, is an herbal remedy used by menopausal women to alleviate hot flashes and other symptoms associated with menopause.  This flavonoid is becoming more common as a menopausal treatment rather than hormone replacement therapy (HRT), due to the increased risk of cancer with HRT usage.    Research has shown that the molecular activity of BC is associated with the regulation of estrogen receptor alpha (ERα) in breast cancer cells.  Mutations in the BRCA1 gene are known to be responsible for about 40-45% of hereditary breast cancers.  Therefore, it is important to verify the anticancer/anti-estrogenic effects of BC through its interaction with ERα, progesterone receptor (PR), and BRCA1.  Previous studies in our laboratory have demonstrated that ERα, PR, and BRCA1 may be possible molecular targets of BC.   In this study, the effects of BC (2.5% triterpene glycosides) alone and in combination with hormones and anti-hormones are studied on cell viability as well as the expression and cytolocalization of ERα, PR, and BRCA1 in ER (+) and PR (+) T-47D breast cancer cells.  To ensure treatment conditions without the presence of endogenous steroids or growth factors, the T-47D cells were cultured in a medium containing 5% charcoal-stripped fetal bovine serum (FBS) for a duration of six days.   The cells were then treated with BC in varying concentrations or in combination with hormones and anti-hormones.  Western blot analysis displayed significant alterations on ERα, PR, and BRCA1 protein levels after 24 hours of treatment with varying BC concentrations (80 μM – 500 μM).   BC displayed a concentration-dependent decrease on ERα and BRCA1 expression, with an 87% reduction of ERα expression and a 43% reduction of BRCA1 expression after treatment with 400 μM BC as compared to control.  The same concentration-dependent trend occurred with the expression of PR.  In order to examine the effects of BC on the growth of the T-47D breast cancer cells, image cytometric analysis with propidium iodide staining was performed to quantify modifications in cell number and viability.  After six days of treatment with 80 μM to 500 μM BC, a 2 – 80% decrease in cell proliferation was observed.  The ideal concentration of BC (400 μM) was combined with hormones and anti-hormones in order to compare this compound with other effectors of ERα, PR, and BRCA1.  Following 24 hours of treatment with a combination of 400 μM BC and 10 nM E2, ERα was downregulated by 90% compared to control and BRCA1 expression was reduced by 70% compared to control.  Once again, the expression of PR following the same treatment exhibited similar effects.  The proliferative effect of E2 was reduced in the presence of BC.  This study may significantly aid in the understanding of the molecular effects of BC on steroid receptors and tumor suppressor genes in breast cancer cells.

 

Nothing to Disclose: KMH, KMA, BD, TD, MQ, SD