Cytotoxicity and Subcellular Distribution of Sea Anemone Equinatoxin II S105-P142 Fragment in Cancer Cells

Abstract

Actinoporin Equinatoxin II (EqtII), a sea anemone cytolysin, has been well known to lyse cells through forming pores on the cell membrane. We show here that an exogenous expression of the EqtII (S105-P142) fragment through gene transferring significantly induced apoptosis in human hepatocellular carcinoma cell line BEL-7404. The EqtII (S105-P142) expression did not alter the cleavage of PARP, as well as levels of Bcl-2 and Bax. Furthermore, the observation under a confocal laser scanning microscope showed that EqtII (S105-P142) colocalized with mitochondria, but not with endoplasmic reticulum and Golgi apparatus. Therefore, the EqtII (S105-P142) fragment was dramatically different from previously reported full length EqtII, which specifically colocalized with Golgi apparatus. The cytotoxicity of EqtII (S105-P142) reported here may provide insights into the utilization of EqtII (S105-P142) as an anticancer agent in future cancer gene therapy.