English

M A Franco Molina,C Rodr Iacute Guez Padilla,L Zapata Monsivais,R Tamez Guerra,E Mendoza Gamboa,M E Roman Calderon,P Zapata Benavides,E E Coronado Ndash Cerda,L G Rivera Morales,C A Sierra Rivera

doi:10.5897/ajmr2015.7551

Abstract

There are many studies about the antitumour effects of Bacillus toxins from different strains or subspecies in different parts of the world. Proteins that selectively kill tumor cells in vitro have potential as anticancer agents. The aim of this study was to evaluate the cytotoxic activity of soluble proteins extracts (SPE) from Mexican strains of B. thuringiensis on murine lymphoma L5178YR cell line. In vitro, L5178YR cells were treated with different concentrations of specific primers (SPE) from B. thuringiensis (0 to 39.85 ig/mL) and cellular viability was evaluated by MTT method and orange acridine/ethidium bromide staining. The mechanism of cell death was evaluated through caspase-3 activation by flow cytometry and TUNEL assays. The study results shows that SPE from B. thuringiensis (GM1-3 h, GM1-24 h, GM1-48 h, GM18-3 h, GM18-24 h, GM18-48 h, HD512-3 h, HD512-24 h, and HD512-48 h) affected the cell viability of L5178YR in a dose-dependent manner which presented higher cytotoxic effect of SPE collected at 3 h independent of the strain used; and the 7% SDS-PAGE presented an electrophoretic profile of proteins in a range of 10 to 100 kDa of the SPE B. thuringiensis. The cytotoxicity is through a mechanism of apoptosis because the caspase-3 activation and TUNEL assays corroborated this result. In conclusion, SPE derived from early culture (3 h) of B. thuringiensis (Bt) GM1, GM18 and HD-512 have in vitro cytotoxic potential on murine lymphoma L5178YR cell line through a mechanism of cell death by apoptosis. Key words: Bacillus thuringiensis, soluble protein extracts, cancer.

Highlights

The entomopathogenic Bacillus thuringiensis, a grampositive bacterium, is naturally found in the soil
We selected the soluble proteins extracts (SPE) of B. thuringiensis treatments from GM1 3h, GM-18 3h, and HD-512 3h, because were the best treatments that affected the cell viability to carry out the experiments with acridine orange/ethidium bromide staining, shown that these treatments induced cell death by apoptosis characteristic by orange color in cells (Figure 1)
In order to confirm the type of cellular death induced by SPE of B. thuringiensis, shown by TUNEL assay the presence of apoptosis (Figure 3)

Summary

Introduction

The entomopathogenic Bacillus thuringiensis, a grampositive bacterium, is naturally found in the soil. VIP were named as such because, unlike the Cry and Cyt proteins, they are mainly produced during the vegetative growth phase of -endotoxins, B. thuringiensis cultures, their secretion can be extended into the sporulation stage. Four basic types of VIP toxins (Vip I, II, III, and IV) have been described, they can be present in a variety of forms within each class (Yu et al, 1997)

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