Effect of EGCG on the expression and activity of P‐glycoprotein in breast cancer cells.

Abstract

Globally breast cancer is the most common cancer in women. The chemotherapy treatment is successful in many instances, however, some patients do not respond satisfactorily. The multi‐drug resistance is considered the principal cause of failure of chemotherapy. There are different mechanisms by which originates multidrug resistance. It has been found that resistance is associated with ABC transporters, mainly P‐glycoprotein (P‐gp). Displayed can be modulated by compounds of natural origin, such as green tea and its polyphenols, including (−)‐Epigallocatechin‐3‐gallate (EGCG). The aim of this study is to observe the effect of EGCG on expression and activity of P‐glycoprotein in cell lines of breast cancer. We use the cell line MCF‐7. We evaluated the effect of EGCG on viability by MTT assay and fluorescence. Also we evaluated the effect on the expression of P‐gp by western blot and immunofluorescence. The activity was measured by the technique of Rhodamine123 accumulation. We found that EGCG does not cause cell death at concentrations below 100 μM. However, concentrations greater than 100 μM produces two types of cell death concentration dependent, EGCG 250 μM produces death by apoptosis and concentrations greater than 500 μM produces death by necrosis. EGCG decreases the expression and activity of Pg‐p in a dose dependent. We conclude that EGCG can reverse drug resistance associated with P‐gp in vitro assays.