Background Black cohosh (BC) is an herbal remedy often used by women to treat symptoms associated with menopause. Research has shown that the molecular activity of BC is associated with estrogen receptor alpha (ER-α) regulation. Progesterone receptor (PR) expression is found to be consistent with ER expression and mutations in the BRCA1 gene, a tumor-suppressor gene, are known to be responsible for about 40%–45% of hereditary breast cancers. Purpose The objective of this study was to determine the effects of BC alone, as well as in combination with hormones and antihormones, on cell viability and expression of ER-α, PR, and BRCA1 in both T-47D and MCF-7 cell lines. Methods Cells were cultured in charcoal-stripped serum prior to their treatment and subsequent protein extraction. Western blot analyses were performed following a Bio-Rad Bradford protein assay and SDS-PAGE gel electrophoresis, with ECL luminescence and Image Studio Lite software. Cellular viability assays were performed using propidium iodine (PI) staining, and the distribution of fluorescent structures was evaluated through confocal microscopy. RT-qPCR analysis was performed on extracted cellular RNA. All statistical analyses were performed using SPSS software, and data was subjected to Kruskal-Wallis testing, followed by post-hoc analysis using the Mann-Whitney U-test to determine the statistical significance of all findings. Results Western blot analysis displayed significant alterations of ER-α, PR, and BRCA1 protein levels after 24-hour treatment with 80–500 μM BC. BC displayed a concentration-dependent decrease on ER-α and BRCA1 expression, with an 87% reduction of ER-α expression and a 43% of BRCA1 expression in T-47D cells compared to control. After six days of treatment with 400 μM BC, a 50% decrease in cell proliferation was observed. Following 24 hours of co-treatment with 400 μM BC and 10 nM E 2 , ER-α was downregulated by 90% and BRCA1 expression was reduced by 70% compared to control. The expression of PR, following the same treatment, exhibited similar effects. The proliferative effect of E 2 was reduced in the presence of BC. Conclusion Black Cohosh demonstrates substantial anti-cancer properties, and this study may significantly aid in the understanding of the molecular effects of BC on ER-α, PR, and BRCA1 in breast cancer cells.

It has been reported that phytoestrogen epigallocatechin gallate (EGCG) suppresses cancer cell proliferation and may have antitumor properties. In this study, we analyzed the effects of EGCG on estrogen receptor α (ERα) and progesterone receptor in hormone-dependent T-47D breast cancer cells. Western blot analysis revealed EGCG induced a concentration-dependent decrease in ERα protein levels, with a 56% reduction occurring with 60 µM EGCG when compared to controls. Downregulation of ERα protein levels was observed after 24-hour co-treatment of T-47D cells with 60 µM EGCG and 10 nM 17β-estradiol (E2). The proliferative effect of E2 on cell viability was reversed when treated in combination with EGCG. In contrast, the combination of EGCG with the pure ER antagonist, ICI 182, 780, showed no further reduction in cell number as only 5% of the cells were viable after 6 days of treatment. These studies may provide further understanding of the interactions among flavonoids and steroid receptors in breast cancer cells.

The North American plant Cimicifuga racemosa, also known as black cohosh (BC), is a herb that recently has gained attention for its hormonal effects. As the usage of hormone replacement therapy is declining due to its adverse effects in women with cancer, many are turning to herbal remedies like BC to treat menopausal symptoms. It is crucial to determine whether the effects of BC involve estrogen receptor-alpha (ERα). Previous studies from our laboratory have shown ERα to be a possible molecular target for BC. In this study, we examined the effects of BC (8% triterpene glycosides) alone and in combination with hormones and antihormones on the cellular viability, expression of ERα and progesterone receptor (PR)-A/B, and cytolocalization of ERα in ER (+) and PR-A/B (+) T-47D breast cancer cells. Cells were cultured and proteins were extracted and quantified. Western blot analysis revealed alterations in the expression of ERα and PR after treatment with BC (5–100 µM). BC induced a concentration-dependent decrease in ERα and PR protein levels when compared to the control. Image cytometric analysis with propidium iodide staining was used to enumerate changes in T-47D cell number and viability. A decrease in T-47D cell viability was observed upon treatment with 5–100 µM BC. The ideal concentration of BC (100 µM) was used in combination with hormones and antihormones in an effort to further understand the possible similarities between this compound and other known effectors of ERα and PR. After a 24-hour concomitant treatment with and/or in combination of BC, estradiol, ICI 182, 780, and Tamoxifen, downregulation of ERα and PR protein levels was observed. Delineating the role of BC in the regulation of ERα, PR, as well as its mechanisms of action, may be important in understanding the influence of BC on hormone receptors in breast cancer.

Bisphenol A (BPA) is a polymerizing agent commonly found in plastics that has been linked to xenoestrogenic activity. In this study, we analyzed the estrogen-like effects of BPA on the expression of estrogen receptor (ER)α and p53 with hormonal and antihormonal treatments in T-47D and MCF-7 cells. Cells were cultured in medium containing 5% charcoal-stripped fetal bovine serum for 6 days to deplete any endogenous steroids or effectors. The cells were then treated for 24 h with 600 nM BPA, which was determined to be the optimal value by a concentration study of BPA from 1 nM to 2 μM. Extracted cellular proteins were quantified and subjected to sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE)/Western blot analysis. The cell proliferation assays were quantified upon exposure to BPA. Laser confocal microscopy was performed to determine the cytolocalization of p53 and ERα upon treatment with BPA. Western blot analysis revealed that BPA caused an increase in the cellular protein p53 in a concentration-dependent manner. While treatment with BPA did not affect the cytolocalization of p53, an increase in cell proliferation was observed. Our studies provide interesting leads to delineate the possible mechanistic relationship among BPA, ER, and tumor suppressor proteins in breast cancer cells.

The atrial natriuretic peptide (ANP) hormone is secreted by cardiac atrial myocytes and acts to regulate blood pressure homeostasis in humans. Previous research indicates ANP treatment significantly decreases the proliferation of human prostate cancer cells, pancreatic adenocarcinoma, and breast cancer cells. Minimal studies have been conducted with regard to ANP regulating tumor suppressor genes and steroid hormone receptors in breast cancer cells. Our study analyzed the effects of ANP in combination with 17β-estradiol (E2) and antiestrogen treatments on p53 and ERα levels in T-47D breast cancer cells. Preliminary studies through Western blot analysis showed that ANP treatment decreases p53 and ERα expression levels in a concentration-dependent (10–100 nM) manner. Treatment with ANP alone, at a 100 nM concentration, causes a decrease of p53 and ERα expression compared with Cs (control stripped), but with E2 and antiestrogen combinations, expression of both protein levels decreased compared with treatments without ANP. Combined treatment with E2, an estrogen antagonist, and ANP decreased cellular proliferation compared with treatments without ANP, except in the case of raloxifene (RAL). Our studies indicate that ANP has potential as a therapeutic breast cancer treatment and should inspire further studies on the molecular mechanism of ANP in T-47D breast cancer cells.