Curcumin Induces Apoptosis via the Capase‐8 Activated Extrinsic Pathway in MDA‐MB‐231 Breast Cancer Cells

AimChemotherapiesfor breast cancer are associated with resistance development, serious side effects, and morbidity. Natural compounds hold promise in both cancer prevention and therapy. Curcumin, a natural polyphenolic compound found inturmeric, has potential cancer treatment efficacy, including apoptosis‐induction in many cancer cell types. Cancer cells are characteristically anti‐apoptotic, highly proliferative and continue to live indefinitely. Control of cell cycle progression and initiation of apoptosis in breast cancer cells is considered to be a potentially effective strategy for the prevention/treatment of the disease. The triple‐negative breast cancer cell line MDA‐MB‐231 does not express progesterone, estrogen, or human epidermal growth factor receptor, is highly aggressive and difficult to treat. This study aims to elucidate the mechanism of curcumin‐induced apoptosis and its cell‐cycle effects in the MDA‐MB‐213 breast cancer cell line.MethodsApoptosis was measured by flow cytometry, fluorescence microscopy, and Western blotting. The cytotoxic activity of curcumin was determined by a sulphorhodamine B assay. Caspase cascade was studied by measuring the activities of caspase‐3, caspase‐8, and caspase‐9 using chromogenic substrates. Cell cycle arrest and cell proliferation were measured by the expression levels of p21Waf‐1 and PCNA, respectively. Mitochondrial involvement of apoptosis was investigated following the translocation of Cytochrome C by Western Blot.ResultsFlow cytometry data suggested that curcumin induced both early and late stage apoptosis in MDA‐MB‐231 cells, which was confirmed by PARP cleavage, fluorscence microscopy as well as activation of caspases. While there were no changes in the level of PCNA, a robust increase was observed in p21Waf‐1 for curcumin treated cells. These results suggest that curcumin might cause cell cycle arrest by increasing the levels of p21 Waf‐1, resulting in an accumulation of cells at G1 phase, leading to G1/S check point arrest. Our data show that curcumin significantly induces caspase‐8 and caspase‐3 activity without modulating caspase‐9 activity, indicating an extrinsic apoptotic pathway. Curcumin did not provoke Cytochrome c release from mitochondria, thus indicating no mitochondrial involvement.ConclusionIn MDA‐MB‐413 cells, curcumin induces apoptosis following an extrinsic pathway via caspase‐8 activation, and cell cycle arrest occurs at the G1 phase. Our findings will aid in the development of futureth erapeutic strategies, including curcumin as a novel treatment supplement.Support or Funding InformationNoneThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.