Anticancer potential of exopolysaccharide from Lactobacillus helveticus MB2-1 on human colon cancer HT-29 cell via apoptosis induction
This study aimed at investigating the anticancer activity of the exopolysaccharide (EPS) isolated from Lactobacillus helveticus MB2-1. The crude EPS from L. helveticus MB2-1 (LHEPS) was fractionated into three fractions, namely LHEPS-1, LHEPS-2 and LHEPS-3. LHEPS-1 exhibited the most effective anti-proliferative activity, which was associated with a stronger inhibition rate and increased lactate dehydrogenase leakage of human colon cancer HT-29 cells. Flow cytometry analyses and colorimetric assay revealed that LHEPS-1 induced the cell cycle arrest by preventing G1 to S transmission and increased apoptosis rate. Furthermore, LHEPS-1 enhanced the production of intracellular reactive oxygen species (ROS) and the activity of caspase-8/9/3, increased the levels of pro-apoptotic (Bax) and mitochondrial cytochrome c, while decreased the anti-apoptotic (Bcl-2) level, indicating that LHEPS-1 might induce apoptosis of HT-29 cells through a ROS-dependent pathway and a mitochondria-dependent pathway. These findings suggest that LHEPS-1 may be developed as an effective food and/or drug for prevention and therapeutics of cancer, especially for human colon cancer.