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

Document Type: Research Articles

Authors

1 Molecular Drug Evaluation Department, National Organization for Drug Control and Research, Giza, Egypt.

2 Department of Microbial Biotechnology, National Research Centre, Dokki, Cairo, Egypt.

Abstract

Objective: The production of new natural pharmaceutical agents that increase the efficiency of chemotherapy
without affecting the normal cells is the goal of all researchers. Therefore, the present study expects to evaluate
the antioxidant and anticancer studies against MCF-7 cell lines of EPS produced by novel Egyptian marine bacterial
strain. Methods: Marine bacterium was isolated, purified and identified by 16S rRNA gene amplification and sequence
analyses. MHMEPS (the produced EPS) was analyzed by Fourier Transform Infra-red (FTIR), monosugars identification
by HPLC, molecular weight estimation and sulfur content were determined. While, in-vitro antioxidants characters
was determined using various methods and anticancer studies against MCF-7 cell lines. Results: Bacillus velezensis
MHM3 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 of
molecular weights Mn of 5.155 ×103 g/mol. The FTIR analysis and periodate oxidation indicate the existence of
α-(1–4) linkage acidic polysaccharide. MHMEPS showed antioxidant scavenging activity against DPPH•, H2O2 and
Metal chelating activity, respectively. So, reducing power method give high activity at 500 μg/ml. MHMEPS hinder
the proliferation of MCF-7 cells at 5-80 μg/ml compared to the control group. Moreover, induced apoptosis was
associated with activation of caspase-3. Also increased cytochrome C levels significantly in a dose-dependent manner
compared with the control. The Caspase-3 activity was raised in MHMEPS treated MCF-7 cells compared with
the control (p<0.05) in a dose-dependent manner. Therefore, the result of DNA fragmentation was confirmed by DNA
ladder assay. We presume that MHMEPS has high potential at its low concentration, as a novel restorative agent for
the treatment of MCF-7 cells, with no cytotoxicity against normal cells.

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