Lactobacillus Plantarum and its Derived Bacteriocin Exhibits Potent Antitumor Activity against Esophageal Cancer Cells.

Esophageal cancer presents a challenge in gastroenterology and traditional chemotherapy and radiation therapy have less therapeutic activity with severe side effects. Thus, there is need for effective and safer alternatives. Probiotics, particularly Lactobacillus plantarum (L. plantarum) and its bacteriocins, might prevent or treat esophageal tumors. We aimed to investigate the use of L. plantarum and its bacteriocin as esophageal cancer therapy. First, we obtained 100 isolates of Lactobacillus spp. from dairy product samples. They screened for bacteriocin production and identified by PCR and gel electrophoresis for 16S ribosomal RNA gene. Bacteriocin was partially purified and tested against two different pathogens. Both L. plantarum and its bacteriocin were examined for cytotoxicity in vitro against esophageal cancer cell line (SK-GT4) and normal rat embryo fibroblast (REF) cells by MTT assay. Apoptosis was determined using an acridine orange /propidium iodide assay. The results showed that the isolate gives a high bacteriocin production about (2000AU/ml). In addition to antimicrobial activity, there was significant anticancer activity. L. plantarum had an IC₅₀ of 51.01 CFU/ml and bacteriocin IC₅₀ of 281.9 AU/ml against cancer cells. Both showed no cytotoxicity towards normal REF cells. Furthermore, there was a significant increase in apoptosis induction and in caspase-3 activity in cancer cells treated with L. plantarum and bacteriocin compared to untreated cells. In conclusion, L. plantarum and its bacteriocin show potent killing effect against esophageal cancer cells with no effect against normal cells indicating safety and selectivity with activation of apoptosis via caspase-3 induction suggesting potential clinical advantage.