title: Blockade of voltage-gated sodium channels inhibits invasion of endocrine-resistant breast cancer cells.
abstract: Voltage-gated Na+ channels (VGSCs) are membrane proteins which are normally expressed in excitable cells but have also been detected in cancer cells, where they are thought to be involved in malignancy progression. In this study we examined the ion current and expression profile of VGSC (Nav1.5) in estrogen receptor (ER)-positive (MCF-7) and silenced (pII) breast cancer cells and its possible influence on their proliferation, motility and invasion. VGSC currents were analysed by whole cell patch clamp recording. Nav1.5 expression and localization, in response to EGF stimulation, was examined by western blotting and immunofluorescence respectively. Cell invasion (under-agarose and Matrigel assays), motility (wound healing assay) and proliferation (MTT assay) were assessed in pII cells in response to VGSC blockers, phenytoin (PHT) and tetrodotoxin (TTX), or by siRNA knockdown of Nav1.5. The effect of PHT and TTX on modulating EGF-induced phosphorylation of Akt and ERK1/2 was determined by western blotting. Total matrix metalloproteinase (MMP) was determined using a fluorometric-based activity assay. The level of various human proteases was detected by using proteome profiler array kit. VGSC currents were detected in pII cells, but were absent in MCF-7. Nav1.5 showed cytoplasmic and perinuclear expression in both MCF-7 and pII cells, with enhanced expression upon EGF stimulation. Treatment of pII cells with PHT, TTX or siRNA significantly reduced invasion towards serum components and EGF, in part through reduction of P-ERK1/2 and proteases such as cathepsin E, kallikrein-10 and MMP-7, as well as total MMP activity. At high concentrations, PHT inhibited motility while TTX reduced cell proliferation. Pharmacological or genetic blockade of Nav1.5 may serve as a potential anti-metastatic therapy for breast cancer.
authors.affiliation: Faculty of Pharmacy, Kuwait University, Safat 13110, Kuwait.
authors.forename: Fatima H
authors.initials: FH
authors.lastname: Mohammed
authors.affiliation: Faculty of Pharmacy, Kuwait University, Safat 13110, Kuwait.
authors.forename: Maitham A
authors.initials: MA
authors.lastname: Khajah
authors.affiliation: Department of Biology, University of York, Heslington, York, YO10 5DD, UK.
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department of Biology, University of York, Heslington, York, YO10 5DD, UK.
authors.forename: William J
authors.initials: WJ
authors.lastname: Brackenbury
authors.affiliation: Faculty of Pharmacy, Kuwait University, Safat 13110, Kuwait.
authors.forename: Yunus A
authors.initials: YA
authors.lastname: Luqmani
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D047628:Estrogen Receptor alpha / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D061986:MCF-7 Cells; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000187:drug effects / Q000235:genetics*; D009361:Neoplasm Invasiveness / Q000235:genetics*; D018408:Patch-Clamp Techniques; D010672:Phenytoin / Q000008:administration & dosage; D013779:Tetrodotoxin / Q000008:administration & dosage
chemical_list: D047628:Estrogen Receptor alpha; D062554:NAV1.5 Voltage-Gated Sodium Channel; C568320:SCN5A protein, human; D013779:Tetrodotoxin; D010672:Phenytoin