Green Tea Extract (Camellia sinensis) as a Potential Antitumoral Agent on Breast Cancer Cells (FS13-04-19)

Abstract

We aimed to obtain a catechin-rich green tea extract (GTE) from Camellia sinensis and to evaluate its antitumor potential on human breast cancer. Green tea (GT) has been extensively studied for its antioxidant property, which is mainly attributed to catechins. These phenolic compounds regulate many cellular targets involved in cancer signaling pathways, including those mediated by p53 tumor suppressor protein.Tea infusion was prepared on a ratio of 1 g:40 mL of boiling distilled water using a combination of temperature and time (70, 75, 80, 85, 90, 95 and 100 ºC/5, 10, 15 min). Infusions were evaluated by polyphenols content (Folin–Ciocalteu's reagent) and antioxidant potential (FRAP). Breast cancer cells (MDA-MB-231 and MCF-7) and non-tumoral cells (MCF-10A), were exposed to different concentrations of GTE (31.5 μg/mL to 1.0 mg/mL) during 24 h-48 h, and cell viability was assessed by Alamar Blue® and Trypan Blue assays. Viability was also acessed in the presence of a p53 protein inibitor, pifithrin-α. Immunocytochemistry and Western blotting analysis were performed to access the expression of p53.Our results demonstrated no influence of extraction condition in the total content of polyphenols and antioxidant potential of GT, and a new extract was obtained at 80 ºC/5 min, then freeze dried to be used in cell culture. After exposure for 24 h, GTE already promoted a cytotoxic effect, reducing viability of both breast cancer cell lines (IC50 MDA-MB-231 = 138,8 μg/mL; IC50 MCF-7 = 324,5 μg/mL) without cytotoxic effect on non-tumoral cells (IC50 MCF-10A = 10,097 μg/mL). In addition, GTE promotes an increase of p53 levels on treated MCF-7 cells, which express the wild-type form of the protein. Interestingly, an opposite phenomenon was evidenced in MDA-MB-231 cells, that express the mutated form of p53, in which protein levels seem to be lower in the presence of the extract.Our data suggests that GTE has anticarcinogenic potential on breast cancer and it is possible that this capacity might be related with the modulation of p53 tumor suppressor protein.FAPERJ, FUNDAÇÃO DO CÂNCER, CAPES, CNPq.