Determination of in vitro Markers of Apoptosis in Breast Cancer Cells Following Chemical Treatments
Goyings, Mary A.
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There are five types of breast cancer. Triple-positive breast cancer is positive for estrogen receptors (ER), progesterone receptors, and human epidermal growth factor (HER2), and is responsive to chemical compounds. Triple-negative breast cancers lack these receptors and as a result treatment options are limited. As such, the mainstay of treatment is traditional chemotherapy. A common treatment for triple-positive breast cancer is the synthetic compound tamoxifen, which is similar to estrogen. Hydroxytamoxifen, an active metabolite of tamoxifen, binds to receptors on breast cancer cells and induces apoptosis. Tamoxifen resistance can occur in once responsive patients, and because of this, alternative treatments are currently being proposed. An emerging field in breast cancer treatment includes the use of plant-based compounds. Honokiol, extract from the Magnolia plant, is a promising new compound that has been shown to have therapeutic effects against triple-positive breast cancer by inducing apoptosis. Distinguishing how markers in this pathway are manipulated from treatment is desirable because as one marker changes, hundreds of other markers, inside and outside of the cell, could change as a result. This study focused on inducing apoptosis in both triple-positive and triple-negative breast cancer with honokiol and hydroxytamoxifen. Of interest is at what concentration both compounds induce apoptosis and how they change the in-vitro markers of apoptosis as a result. Hydroxytamoxifen induced apoptosis in both cell lines, while honokiol did not appear to induce apoptosis in either cell line. In the triple-positive cell line, one marker of apoptosis decreased in response to 12.5μM honokiol while five markers increased expression.