alpha O-Conotoxin GeXIVA Inhibits the Growth of Breast Cancer Cells via Interaction with alpha 9 Nicotine Acetylcholine Receptors

The alpha 9-containing nicotinic acetylcholine receptor (nAChR) is increasingly emerging as a new tumor target owing to its high expression specificity in breast cancer. alpha O-Conotoxin GeXIVA is a potent antagonist of alpha 9 alpha 10 nAChR. Nevertheless, the anti-tumor effect of GeXIVA on breast cancer cells remains unclear. Cell Counting Kit-8 assay was used to study the cell viability of breast cancer MDA-MD-157 cells and human normal breast epithelial cells, which were exposed to different doses of GeXIVA. Flow cytometry was adopted to detect the cell cycle arrest and apoptosis of GeXIVA in breast cancer cells. Migration ability was analyzed by wound healing assay. Western blot (WB), quantitative real-time PCR (QRT-PCR) and flow cytometry were used to determine expression of alpha 9-nAChR. Stable MDA-MB-157 breast cancer cell line, with the alpha 9-nAChR subunit knocked out (KO), was established using the CRISPR/Cas9 technique. GeXIVA was able to significantly inhibit the proliferation and promote apoptosis of breast cancer MDA-MB-157 cells. Furthermore, the proliferation of breast cancer MDA-MB-157 cells was inhibited by GeXIVA, which caused cell cycle arrest through downregulating alpha 9-nAChR. GeXIVA could suppress MDA-MB-157 cell migration as well. This demonstrates that GeXIVA induced a downregulation of alpha 9-nAChR expression, and the growth of MDA-MB-157 alpha 9-nAChR KO cell line was inhibited as well, due to alpha 9-nAChR deletion. GeXIVA inhibits the growth of breast cancer cell MDA-MB-157 cells in vitro and may occur in a mechanism abolishing alpha 9-nAChR.