Anti-tumor activity of Escherichia coli Shiga toxin A subunit delivered by SF9 insect cells

Cancer remains a major health problem around the world. A Shiga toxin is a bacterial toxin often produced by Shigella dysenteriae and Escherichia coli. A subunit of the Shiga toxin (StxA) is a cytotoxic agent which could be used to induce death in cancer cells. StxA expressed from baculovirus was evaluated in a pTriEx™ expression vector. The baculovirus vector was used for the A subunit delivery of StxA. StxA cell cytotoxicity was induced by the virus and assessed in the MCF7 and HeLa cell lines. In addition, the breast cancer cytotoxicity of the expressed StxA was also assessed in a cancer induced in mice. The cytotoxicity of the recombinant StxA baculovirus with different multiplicities of infection (MOI) was measured. The results showed that significant cytotoxicity can be induced on the mammalian epithelial breast cancer cell lines, MCF7 and HeLa cells with MOI ≥ 2. The results also showed that a malignant tumor induced by MCF7 could be inhibited in a mouse cancer model. Therefore, it can be concluded that StxA, expressed by baculovirus, could be used for in vitro and in vivo gene delivery. In this study StxA, delivered by the baculovirus inhibited cell proliferation, and eliminated HeLa and MCF7 cells, in vitro. In conclusion, this method can be used as a safe alternative for anticancer drug delivery inside cancer cells.