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-1α (HIF-1α) and upregulated the expression of tissue inhibitor of metalloproteinases-3 (TIMP-3), hypoxia-inducible factor-2α (HIF-2α), 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.

Optimization of anticancer exopolysaccharide production from probiotic Lactobacillus acidophilus by response surface methodology.

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths in the Western world. Recently, much attention has been focused on decreasing the risk of CRC by consuming probiotics. In the present study, exopolysaccharide (EPS) extracted from Lactobacillus acidophilus was found to inhibit the growth of CaCo2 colon cancer cell line in a dose-dependent manner. The experiment was performed in both normoxic and hypoxic conditions, and EPS was found to reduce the survival of CaCo2 cell line in both the conditions. Quantitative polymerase chain reaction (qPCR) studies demonstrated that EPS treatment upregulated the expression of peroxisome proliferator activator receptor-γ (PPAR-γ) in both normoxia and hypoxia conditions, whereas it upregulated the expression of erythropoietin (EPO) in the normoxic condition, but there was no significant expression under hypoxic conditions. Hence, the EPS production was optimized by Plackett-Burman design followed by central composite rotatory design. The optimized production of EPS at 24 hr was found to be 400 mg/L. During batch cultivation the production peaked at 21 hr, resulting in an EPS concentration of 597 mg/L.

PEG-PHB-glutaminase nanoparticle inhibits cancer cell proliferation in vitro through glutamine deprivation.

In this study, we demonstrate that L-glutaminase, a marine bacterial enzyme with a molecular weight of 37 kDa, inhibits cancer cell proliferation in vitro through glutamine deprivation. The concentration of the enzyme reducing the viability of HeLa cells to 50% was determined to be 12.5 µg/mL; the function of L-glutaminase in controlling cell proliferation was further analysed by BrdU assays. To increase its stability and bioavailability, the enzyme was immobilized on polyethyleneglycol (PEG)-polyhydroxybutyrate (PHB) nanoparticles. A dented anatomy of the HeLa cells was observed under fluorescence and confocal microscopy when they were incubated with L-glutaminase and in glutamine-free medium, as also a 3-fold increase in caspase-3 activity was observed under the same conditions. Blebbed cytoplasm and shrunken nuclei were observed in treated cells under transmission electron microscopy (TEM). Finally, the influence of the enzyme on cell cycle and DNA damage was evaluated using flow cytometry and DNA fragmentation assays. The results confirmed significant damage to the DNA of HeLa cells incubated with L-glutaminase and in glutamine-free medium. These studies attest to the significant role played by L-glutaminase against proliferation in cancer cells through glutamine deprivation.