Differential effects of phenolic extracts from red-fleshed apple peels and flesh induced G1 cell cycle arrest and apoptosis in human breast cancer MDA-MB-231 cells.

Red-fleshedapples are preferredbecause of their high content of phenolics and antioxidants in peel and pulp. Herein, we evaluated the mechanisms of apple peel polyphenolic extracts (APP) and apple flesh polyphenolic extracts (AFP) from the new red-fleshed apple in inhibiting cell proliferation and inducing apoptosis on human breast cancer MDA-MB-231 cells. The antiproliferative activities were determined by the CCK8 assay. The expression of proteins was determined using Western blot. We found that the content of polyphenols and flavonoids in APP was significantly higher than that in AFP, and 14 main phenolic compounds in APP and AFP were quantified using UPLC-MS/MS techniques. Besides, the significant inhibition effects of APP and AFP were achieved through Akt pathway by inducing apoptosis (significantly upregulating reactive oxygen species [ROS] levels, and downregulating expression of pAkt, pBad, Bcl-2, promoting Cytochrome c release, activating Cle-Caspase 9, and inducing expressions of Cle-Caspase 3 and Cle-PARP), and inducing G0/G1 cell cycle arrest (increased expressions of p-p53 and p21 and decreased expressions of PCNA and Cyclin D1). And the inhibition effect of APP was stronger than that of AFP. These results suggest that AFP and APP may be excellent sources of natural chemicals for treating triple-negative breast cancer MDA-MB-231 cells. PRACTICAL APPLICATION: The effects of antiproliferation of phenolic extracts from red-fleshed apple peels and flesh on human breast cancer MDA-MB-231 cells were evaluated. The data may clarify the functional parts of red-fleshed apple and provide some basis for scientific researchers and consumers to recognize and exploit red-fleshed apple.