¹Department of Plant Protection, Faculty of Agriculture Sciences and Technology, Sivas Science and Technology University, Turkey
²Department of Biochemistry, Faculty of Medicine, Aydin Adnan Menderes University, Aydın, Turkey DOI : 10.29228/jrp.38 Breast cancer is the most common malign tumor among women in the world and is the main lineage of cancer deaths due to its susceptibility to metastasis. Letrozole is used as an aromatase inhibitor and as anti-estrogenic, utilized to cure the breast cancer. Quercetin is a powerful antioxidant known as free radical scavenger, an important flavonoid. The current study was performed to examine the mechanism of action of the combination letrozole and quercetin in human breast cancer cells and to investigate the efficacy of letrozole and quercetin in breast cancer cells. Human breast cancer cells (MCF-7 and MDA-MB-231) were incubated with letrozole (10nM) and/or quercetin (5ng/mL). Cell proliferation of letrozole and quercetin in breast cancer cell lines was measured by MTT. Western blotting and qPCR were practiced to measure the protein and gene expression levels of ER-α, ER-β, Bax, Bcl-2, Foxo1, Foxo3, VEGF, Akt. Results from the study showed that letrozole and quercetin combination inhibited cell growth in MCF-7 and MDA-MB-231 cells and induced mitochondrial apoptosis. Letrozole and quercetin combination therapy may provide contributions to the development of new therapeutic drugs as an effective treatment approach for breast cancer patients. Keywords : Breast cancer; letrozole; quercetin; apoptosis; FOXOs; estrogen