Abstract
Colon cancer is one of the most common cancer around the world. Exopolysaccharides (EPSs) produced by lactobacilli as potential prebiotics have been found to have an anti-tumor effect. In this study, lyophilized EPSs of four Lactobacillus spp. for their impact on apoptosis in colon cancer cells (HT-29) was evaluated using flow cytometry. The relationship between capability of a lactobacilli-EPS to induce apoptosis and their monosaccharide composition, molecular weight (MW), and linkage type was investigated by HPLC, SEC, and NMR, respectively. Changes in apoptotic-markers were examined by qPCR and Western Blotting. EPSs were capable of inhibiting proliferation in a time-dependent manner and induced apoptosis via increasing the expression of Bax, Caspase 3 and 9 while decreasing Bcl-2 and Survivin. All EPSs contained mannose, glucose, and N-acetylglucosamine with different relative proportions. Some contained arabinose or fructose. MW ranged from 102–104Da with two or three fractions. EPS of L. delbrueckii ssp. bulgaricus B3 having the highest amount of mannose and the lowest amount of glucose, showed the highest apoptosis induction. In conclusion, lactobacilli-EPSs inhibit cell proliferation in HT-29 via apoptosis. Results suggest that a relationship exists between the ability of EPS to induce apoptosis and its mannose and glucose composition.
Highlights
Today, cancer is one of the most important health problem leading to death
EPSs produced by lactic acid bacteria (LAB) are one of the important component that have a key role in probiotic activity including anti-proliferative effect, immunomodulation, and adhesion[13,17,50]
The lactobacilli strains studied here produced in a decent amount of EPS relative to the lactobacilli EPSs studied in the literature[15,52,53]
Summary
Cancer is one of the most important health problem leading to death. Colorectal cancer is the second most common cause of cancer deaths in the world[1,2]. Li et al purified three fractions of EPS isolated from L. helveticus MB2-1 and evaluated their structure and antioxidant activities in vitro[28] They reported that the molecular weights of EPSs were similar, their sugar compositions and antioxidant effect were different as well as their anti-cancer impact on colon cancer cells[28,29]. We investigated the EPS produced by various Lactobacillus spp. and their impact on proliferation and apoptosis in colon cancer cells. We performed a chemical and structural characterization of lactobacilli EPSs including molecular weight, monosaccharide composition, and linkage type. We evaluated their structural, characteristic effects on apoptosis
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