P-195: Thymoquinone Increases Efficacy of Tamoxifen Induced Apoptosis in Human Breast Cancer MCF-7 Cells: In Vitro

Background: The objective of this study is to evaluate combined effect of Thymoquinone (The main active component of black seeds) with Tamoxifen drug on apoptosis of human breast cancer MCF-7 cells (Noninvasive human breast cancer cell line, estrogen receptor positive). Materials and Methods: The human breast cancer MCF- 7 cells were treated with Tamoxifen (2 μM) alone or in combination with Thymoquinone (150 μM). Morphological conformation of cell death in MCF-7 cells treated by Tamoxifen, Thymoquinone and combination after 48h were studied by Acridine orange/ethidium bromide staining and TUNEL assay. Statistical analysis was conducted using One-Way ANOVA and Tukey&#039;s test. All statistical analysis was done by using SPSS software (version19.0). In all cases, p values<0.05 was significantly considered. Results: The data of TUNEL assay and Acridine orange/ethidium bromide staining in MCF-7 cells after 48h treatment were indicated that Tamoxifen and the Thymoquinone alone or in combination significantly increased apoptotic index (p<0.001). Also, TUNEL staining showed an increased number of apoptotic cells in synergic group. It is indicated that higher doses of Thymoquinone in combination with lower dose of Tamoxifen (2 μM) induces apoptosis in MCF-7 cells. Herein, we showed that high doses of Thymoquinone in normal cells could be free of side effects of this natural component. Conclusion: This study indicates that high doses of Thymoquinone acts for lowering the dose of Tamoxifen and shortening the time course of Tamoxifen exposure in estrogen receptor positive breast cancer cells in a safe and non-hazardous manner. These data could bring a new light for the treatment of breast cancer and also for other types of cancer patients.