IOD-NaTx, a scorpion Nav channel toxin induces apoptosis and inhibits growth of highly aggressive breast cancer cells

Abstract

Abstract Metastatic breast cancer is the most lethal cancer in women that involved various molecular mechanisms. Nav1.5, a voltage-gated sodium channels, is overexpressed in high metastatic breast cancer cells, MDA-MB-231. In this study, we investigated the anti-cancer effect of a new Na+ channel blocker, IOD-NaTx toxin from scorpion. IOD-NaTx toxin contains 66 amino acids that forms three disulfide bonds, converse with other Na+ channels. It was expressed recombinantly in E.coli and purified by nickel affinity chromatography. The cancer cell cytotoxicity was investigated by MTT assay and IC50 of rIOD-NaTx was determined 8µM. Morphological properties of apoptotic cells were observed following toxin treatment. Cell cycle arrest in sub-G1 and increasing amount of p53 mRNA expression also confirmed apoptosis induction in toxin treated cells. IOD-NaTx significantly inhibited mRNA expression of several critical genes involved in breast cancer progression, AKT1, VEGF, LIF, TNF-α. The association of these genes with Nav1.5 channel and PI3K/AKT pathway suggests that IOD-NaTx may affect dufferent pathways through inhibittion of this channel. Fluorescent microscopy analysis showed IOD-NaTx interacte with cancer cells and could penetrate to cells. Therfore, recombinant IOD-NaTx can be considered as an therapeutic cell penetrating peptide for targeting breast cancer cells.