Overexpression and Cytocidal Activity of Parasporin-1 from Bacillus thuringiensis against Human Cancer Cell Lines

Abstract

Parasporin (PS) is a newly discovered family of cytocidal proteins isolated from Bacillus thuringiensis (Bt). Parasporin-1 gene was subcloned into pET-30a expression vector and overexpressed in Escherichia coli under the control of the T7 RNA polymerase promoter. The parasporin-1 gene was expressed in the strain E. coli BL21 (DE3). The purified, expressed, and trypsin-activated protein exhibited cytotoxic activity against three selected cancer cell lines (Vero, HeLa and Hep G2). Noticeable phenotypic changes, including cell morphology and cell-cell adhesion were observed in the culture after the treatment with recombinant parasporin. Further evidence of apoptosis includes the shrinkage of cells, cell bleb formation and cells detachment in the culture plates. This effect is probably due to the direct effect of activated parasporin on the cell oxidation system of cancer cell (Vero, HeLa and Hep G2). In conclusion, the study demonstrates good cytocidal activity exhibited of the expressed parasporin proteins by reducing the cell viability of the three selected cancer cell lines.