The role of Epithelial sodium channel (ENaC) in cell proliferation and tunneling nanotube (TnT) formation in benign mesothelial cells and malignant pleural mesothelioma (MPM) cells

Abstract

Introduction: The role of ENaC in pleural fluid turnover is important in pleural effusions, a clinical hallmark of MPM. Biochemical and functional expression of ENaC is reported both in normal and in MPM cells. ENaC activity also influences cell cycle progression thus it may influence cell proliferation and thus tumor growth. TnT was recently described as a structure favoring direct distant cell-cell communication, however ENaC contribution in TnT development has not been investigated. Aim: To assess the role of ENaC in cell proliferation and TnT formation in the context of MPM pathobiology. Methods: MeT-5A (benign mesothelial cells), M14K (epithelioid MPM cells), MSTO (biphasic MPM cells) and ZL34 (sarcomatoid MPM cells) were used in the study. Cell proliferation over 3 days and TnT formation in 1 day was tested with 10% FBS RPMI (Controls) or by ENaC inhibition with Amiloride (AM, 10-5 M in 10% FBS RPMI). Crystal violet staining was used to assess changes in cell proliferation and for visualizing TnTs. Results: Cell proliferation post AM treatments were lower in MSTO and ZL34 cell lines at day 3, (MSTO Control 1888.3±106%, AM 1610.5±115.5%, p Conclusions: MeT-5A and M14K cell proliferation was unaffected by ENaC inhibition. AM significantly lowered cell proliferation on MSTO and ZL34 cell lines. TnT formation was unaffected in all cell lines regardless of ENaC activity.