CYTOTOXICITY EFFECT OF BACTERIOCIN LIKE INHIBITORY SUBSTANCE (BLIS) PRODUCED BY PROBIOTIC LACTOBACILLUS CASEI TA0021 ON COLORECTAL CANCER CELL LINES (HT-29

Background and Aim:Colorectal cancer (CRC) is known as the third most common form of cancer. Diverse therapies such as chemotherapy, immunotherapy and radiation have shown beneficial effects, but are limited due to their adverse effects on the target. Probiotic bacteria and their metabolites are long known to have significant role in decreasing the viability of colorectal cancer cells. This study provided evidence for the anti-cancer effect of a bacteriocin like inhibitory substance produced by a locally isolated L.casei TA0021 strain on colorectal cancer cells HT-29 cell lines invitro.Methods:The supernatant fluid of L.casei TA0021 showing inhibitory effects towards Salmonella typhimurium, S.enteriditis and E.coli K99, were subjected to catalase and proteolytic enzymes. The inhibitory proteins in the supernatant fluids were precipitated by 60% ammonium sulphate, dialyzed and ultra-filtered using 10KDA filter membranes. The inhibitory proteins accumulated in the filtrate were concentrated using PEG(6000) and saved recorded as BLIS.Results: Non- denaturing gel indicated a band of approximately 9 KDa to be responsible for the activity. Confluently grown HT-29 cell lines were treated for 72 h with 1%,3%,5%,10% (v/v) of BLIS, incubated at 37˚C under 5% CO2 condition. Cell growth inhibition was measured by MTT assay kit and IC50 values calculated.Conclusion: Based on the results, the supernatant fluids of L.casei possessed inhibitory actions towards the indicator strains, sensitive to the action of proteolytic enzymes, while unaffected by acidic pH and catalase enzyme. IC50 valve of BLIS against HT-29 cells was 5%(v/v), and significant (86%) cytotoxicity levels on the cancer cells were recorded.

Keywords:

bacteriocin , Lactobacillus casei , colorectal cancer (CRC) , cytotoxicity , HT-29 cell line