Functional expression of voltage-gated sodium channels Nav1.5 in human breast cancer cell line MDA-MB-231.

Voltage-gated sodium channels (VGSCs) are known to be involved in the initiation and progression of many malignancies, and the different subtypes of VGSCs play important roles in the metastasis cascade of many tumors. This study investigated the functional expression of Nav1.5 and its effect on invasion behavior of human breast cancer cell line MDA-MB-231. The mRNA and protein expression of Nav1.5 was detected by real time PCR, Western Blot and immunofluorescence. The effects of Nav1.5 on cell proliferation, migration and invasion were respectively assessed by MTT and Transwell. The effects of Nav1.5 on the secretion of matrix metalloproteases (MMPs) by MDA-MB-231 were analyzed by RT-PCR. The over-expressed Nav1.5 was present on the membrane of MDA-MB-231 cells. The invasion ability in vitro and the MMP-9 mRNA expression were respectively decreased to (47.82+/-0.53)% and (43.97+/-0.64)% (P<0.05) respectively in MDA-MB-231 cells treated with VGSCs specific inhibitor tetrodotoxin (TTX) by blocking Nav1.5 activity. It was concluded that Nav1.5 functional expression potentiated the invasive behavior of human breast cancer cell line MDA-MB-231 by increasing the secretion of MMP-9.