In vitro evaluation of anticancer properties of exopolysaccharides from Lactobacillus acidophilus in colon cancer cell lines

The present work aims at studying the effect of exopolysaccharides (EPS) from Lactobacillus acidophilus on the colon cancer cell lines in vitro. Initial analysis showed that EPS has antioxidative properties. EPS was also found to induce cytotoxicity in two colon cancer cell lines, viz. HCT15 and CaCo2 under normoxia and hypoxia. The membrane integrity was also found to be affected in EPS-treated cells. Once the toxic concentration was determined (5 mg/ml), the effect of EPS on the messenger RNA (mRNA) expression of various genes was studied by quantitative real-time (RT)-PCR under both normoxic and hypoxic conditions. The results suggest that EPS downregulated the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1 alpha (HIF-1 alpha) and upregulated the expression of tissue inhibitor of metalloproteinases-3 (TIMP-3), hypoxia-inducible factor-2 alpha (HIF-2 alpha), and hemeoxygenase-1 (HO-1). An increase in plasminogen activator inhibitor-1 (PAI-1) was also observed. These results show that EPS may inhibit the expressions of genes involved in tumor angiogenesis and survival. Increase in the expression of HO-1 also shows that EPS have antioxidative properties.