IN VITRO SCREENING OF HERBAL MEDICINE FOR SYNERGISTIC EFFECT WITH TAMOXIFEN ON MCF-7 BREAST CANCER CELLS

Breast cancer stands as the most prevalent form of malignancy and is the second leading cause of death among women. Despite tamoxifen (TAM) continuing to be a primary choice for the prevention and treatment of estrogen-receptor (ER) positive breast tumors, resistance to TAM poses a significant clinical hurdle in breast cancer therapy. Consequently, there has been a rising interest in discovering new agents, particularly those derived from plants, that can augment TAM sensitivity in breast cancer cells. This study aims to explore herbal medicines capable of enhancing the anticancer effects of TAM in ER-positive breast cancer cells, specifically MCF-7 cells, utilizing conventional bioassays such as MTT, colony formation assay, and immunocytochemistry. Among 25 samples tested, Polygala chinensis L. extract (PCE) showed strong synergism with TAM against MCF-7 cell survival, evidenced by the combination of Bliss analysis and Chou-Talalay analysis. Additionally, co-treatment of MCF-7 cells with PCE and TAM more significantly suppressed colony formation and the nuclear expression of proliferative marker Ki67 compared to TAM alone. These findings imply that PCE potentiates the anti-proliferative effect of TAM in MCF-7 breast cancer cells and may become a promising candidate in the treatment of breast cancer.