Apoptotic Activity of Lactobacillus plantarum DGK-17-Fermented Soybean Seed Extract in Human Colon Cancer Cells via ROS-JNK Signaling Pathway.

Fermented food has been always possesses upper hand compared to normal food due to its antibacterial, antioxidant, and anticancer properties. Soybeans, which have high nutritional value, are widely consumed in Korea. In this study, soybean seed powder fermented with Lactobacillus plantarum DGK-17, which was previously isolated from kimchi, showed anticancer potential. Fermented soybean extract (FSE) resulted in morphological changes, reduction of cancer cell colony formation and apoptotic cell death of HCT-116 colon cancer cells in a dose-dependent manner, and IC50 value of 111 μg. FSE treatment caused reduction of cell growth in a dose-dependent manner via release of lactate dehydrogenase. FSE treatment induced HCT-116 apoptotic cell death as confirmed by the presence of fragmented nuclei, oxidative burst, and reduced mitochondrial membrane potential (ΔΨm ). Further, FSE treatment sensitized cells to ER stress via IRE1-α induction. FSE treatment also resulted in JNK activation, subsequently causing activation of Bax and downregulation of BCl2. Weakened mitochondrial membrane potential (ΔΨm ) also caused release of Cyto C, further activating caspase-mediated cell death. Therefore, this study reveals the apoptotic role of DGK-17-fermented soybean seed extract in human colon cancer HCT-116 cells.