Vacuolar ATPase driven potassium transport in highly metastatic breast cancer cells

Abstract

Breast cancer is the second leading cause of death in women and thus has received a great deal of attention by researchers. Recent studies suggested decreased occurrence of cancer in patients treated with cardiac glycosides (CGs) for heart conditions. Because CGs induce their cellular effects via the Na(+), K(+) ATPase (Na-K), we treated four breast cancer cell lines (MCF-7, T47D, MDA-MB453, and MDA-MB231) and a non-cancerous breast ductal epithelial cell line (MCF-10A) with ouabain, a well-characterized CG, and measured cell proliferation by measuring bromodeoxyuridine incorporation. Ouabain (1μM) decreased cell proliferation in all cell lines studied except MDA-MB453 cells. Western blot of Na-K α and β subunits showed α1, α3, and β1 expression in all cell lines except MDA-MB453 cells where Na-K protein and mRNA were absent. Potassium uptake, measured as rubidium ((86)Rb) flux, and intracellular potassium were both significantly higher in MDA-MB453 cells compared to MCF-10A cells. RT-qPCR suggested a 7 fold increase in voltage-gated potassium channel (KCNQ2) expression in MDA-MB453 cells compared to MCF-10A cells. Inhibition of KCNQ2 prevented cell growth and (86)Rb uptake in MDA-MB453 cells but not in MCF-10A cells. All cancer cells had significantly higher vacuolar H-ATPase (V-ATPase) activity than MCF-10A cells. Inhibition of V-ATPase decreased (86)Rb uptake and intracellular potassium in MDA-MB453 cells but not in MCF-10A cells. The findings point to the absence of Na-K, high hERG and KCNQ2 expression, elevated V-ATPase activity and sensitivity to V-ATPase inhibitors in MDA-MB453. We conclude that cancer cells exhibit fundamentally different metabolic pathways for maintenance of intracellular ion homeostasis.

Anticancer redox activity of gallium nanoparticles accompanied with low dose of gamma radiation in female mice

“…36,37,45 More studies to investigate the mechanistic anticancer effect of GaNPs are required Cancer cells exhibit fundamentally different metabolic pathways for maintenance of intracellular ion homeostasis concerning Na+/K+-ATPase activity markedly depends on tumor cell or cancer type. 58 In this regard, the obtained data showed a significant decrease of Na+/K+-ATPase activity in cancerbearing mice (EC group) in comparison with other treated groups (EC+R and EC+GaNPs+R). This finding is consistent with others 59,60 who reported that hepatic Na+/K+-ATPase activity concentration was significantly decreased in tumor-bearing mice when compared to control.…”

Bioelectrical regulation of cell cycle and the planarian model system

“…For example, in many breast cancer cell lines, there is an upregulation in the expression of V-ATPases in the cell membrane whereas overexpression in normal cells confers a neoplastic phenotype [85, 86]. Another voltage-gated proton pump Hv1, critical for proton transfer, is overexpressed in high-grade metastatic human breast cancer cell lines such as MCF-7, but shows minimal expression in low-grade metastatic breast tumors [87].…”

Regulation of Na+,K+-ATPase isoforms and phospholemman (FXYD1) in skeletal muscle fibre types by exercise training and cold-water immersion in men

“…The monoclonal NKA β 1 antibody (#MA3-930) has been used previously in this journal to quantify β 1 protein in human muscle samples despite no clear evaluation of specificity of the lot used (Murphy et al , 2004). As β 1 protein is heavily glycosylated (Vagin et al , 2006), and highly expressed in human cancer cell lines (Salyer et al , 2013), we tested the specificity of our β 1 antibody lot using deglycosylated (PNGase treated for 3 h) and control human crude skeletal muscle samples and two human breast cancer (MDA-MB-231 and MCF10.Ca1d) and control (HEKs, human embryonic kidney) cell lines (Fig. 2D).…”