Exopolysaccharide from Marine Bacillus velezensis MHM3 Induces Apoptosis of Human Breast Cancer MCF-7 Cells through a Mitochondrial Pathway

摘要

Objective: The production of new natural pharmaceutical agents that increase the efficiency of chemotherapywithout affecting the normal cells is the goal of all researchers. Therefore, the present study expects to evaluatethe antioxidant and anticancer studies against MCF-7 cell lines of EPS produced by novel Egyptian marine bacterialstrain. Methods: Marine bacterium was isolated, purified and identified by 16S rRNA gene amplification and sequenceanalyses. MHMEPS (the produced EPS) was analyzed by Fourier Transform Infra-red (FTIR), monosugars identificationby HPLC, molecular weight estimation and sulfur content were determined. While, in-vitro antioxidants characterswas determined using various methods and anticancer studies against MCF-7 cell lines. Results: Bacillus velezensisMHM3 produced 5.8 g/L of MHMEPS. The chemical analysis of MHMEPS showed 24% uronic acid and 18.19%sulfate and monosugars glucuronic acid, glucose, fructose and rhamnose with molar ratio of 4.00: 2.00: 1.00: 0.13,correspondingly, with an overall weight average molecular weight Mw of 1.145×104 g/mol and the number average ofmolecular weights Mn of 5.155 ×103 g/mol. The FTIR analysis and periodate oxidation indicate the existence ofα-(1–4) linkage acidic polysaccharide. MHMEPS showed antioxidant scavenging activity against DPPH?, H2O2 andMetal chelating activity, respectively. So, reducing power method give high activity at 500 μg/ml. MHMEPS hinderthe proliferation of MCF-7 cells at 5-80 μg/ml compared to the control group. Moreover, induced apoptosis wasassociated with activation of caspase-3. Also increased cytochrome C levels significantly in a dose-dependent mannercompared with the control. The Caspase-3 activity was raised in MHMEPS treated MCF-7 cells compared withthe control (p0.05) in a dose-dependent manner. Therefore, the result of DNA fragmentation was confirmed by DNAladder assay. We presume that MHMEPS has high potential at its low concentration, as a novel restorative agent forthe treatment of MCF-7 cells, with no cytotoxicity against normal cells.