Human neoplastic mesothelial cells express voltage-gated sodium channels involved in cell motility

The International Journal of Biochemistry & Cell Biology. Received 23 August 2005; revised 26 November 2005; accepted 8 December 2005. Available online 17 January 2006. doi:10.1016/j.biocel.2005.12.003 [Link]

Gianluca Fulgenzi^a, Laura Graciotti^{a, b}, Monica Faronato^a, Maria Virginia Soldovieri^d, Francesco Miceli^d, Salvatore Amoroso^c, Lucio Annunziato^d, Antonio Procopio^{a, b} and Maurizio Taglialatela^{d, e}

^aDepartment of Molecular Pathology and Innovative Therapies, Polytechnic University of Marche, Via Ranieri, Ancona 60131, Italy
^bCenter of Cytology, INRCA-IRCCS, Ancona, Italy
^cDepartment of Neuroscience, Polytechnic University of Marche, Ancona, Italy
^dDivision of Pharmacology, Department of Neuroscience, University Federico II, Napoli, Italy
^eDepartment of Health Sciences, University of Molise, Campobasso, Italy

Abstract

Given the pivotal role of ion channels in neoplastic transformation, the aim of the present study has been to assess possible differences in the expression patterns of voltage-gated monovalent cationic (Na+ and K+) currents between normal and neoplastic mesothelial cells (NM, MPM, respectively), and to evaluate the role of specific ion channels in mesothelioma cells proliferation, apoptosis, and motility. To achieve this aim, membrane currents expressed in NM and MPM cells derived from surgically-removed human specimens were investigated by means of patch-clamp electrophysiology. NM cells were found to express three main classes of K+ currents, which were defined as KIR, maxiKCa, and KV currents on the basis of their biophysical and pharmacological properties. Each of these K+ currents was absent in MPM cells; by contrast, MPM cells revealed the novel appearance of tetrodotoxin (TTX)-sensitive voltage-gated Na+ currents undetected in normal mesothelial cells. Reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time PCR analysis of MPM cells transcripts showed significant expression of the mRNAs encoding for NaV1.2, and NaV1.6, and NaV1.7 (and less so for NaV1.3, NaV1.4, and NaV1.5) main voltage-gated sodium channel (VGSC) α-subunit(s). Interestingly, blockade of VGSCs with TTX decreased mesothelioma cell migration in in vitro motility assays; on the other hand, TTX failed to interfere with cell viability, proliferation, and apoptosis progression triggered by UV exposure. In summary, the results of the present study suggest that VGSCs expression in MPM cells may favor the increased motility of the neoplastic cells, a phenotypic feature often associated with the malignant phenotype.

Keywords: Voltage-gated potassium channel; Voltage-gated sodium channel; Mesothelioma; Mesothelium; Patch-clamp