Cisplatin Activates Volume-Sensitive Like Chloride Channels Via Purinergic Receptor Pathways in Nasopharyngeal Carcinoma Cells

Abstract

Cisplatin-based concomitant chemoradiotherapy is considered as the standard treatment for locally advanced nasopharyngeal carcinoma patients. However, the curative efficacy of cisplatin-based chemotherapy is limited because of the occurrence of cisplatin resistance. Some researches indicate that activating the volume-sensitive Cl(-) channel might be a new strategy for the reduction of cisplatin resistance. However, little is known about the activation pathway of the Cl(-) channels activated by cisplatin. In this study, the cisplatin-activated chloride current was investigated using the whole cell patch-clamp technique in the poorly differentiated nasopharyngeal carcinoma cells (CNE-2Z cells), and the activation pathway of the current was also discussed. The results showed that extracellular application of cisplatin activated a Cl(-) current, showing the properties of significant outward rectification, intracellular ATP dependency, and a selectivity sequence of I(-) > Br(-) > Cl(-) > gluconate, and being inhibited by the Cl(-) channel inhibitors tamoxifen and extracellular ATP. These characteristics are similar to those of the volume-sensitive Cl(-) current in CNE-2Z cells, indicating that cisplatin induces the Cl(-) current by activating the volume-sensitive like chloride channel. The cisplatin-activated current was blocked by suramin (a wide-spectrum purinergic antagonist) and RB2 (a relatively selective P2Y antagonist). In addition, the current was depressed by extracellular application of apyrase. The apoptotic volume decrease induced by cisplatin was also attenuated by RB2. P2Y receptors were expressed in CNE-2Z cells. These results suggest that cisplatin can induce a Cl(-) current by activating volume-sensitive like Cl(-) channels through the P2Y purinoceptor pathway.

Cell Volume-Activated and Volume-Correlated Anion Channels in Mammalian Cells: Their Biophysical, Molecular, and Pharmacological Properties

“…The VSOR currents were found to be voltagedependently inhibited by a tyrosine kinase inhibitor, genistein (Bryan-Sisneros et al, 2000;Shuba et al, 2000;, but not by its inactive analog daidzein . An antiestrogen, tamoxifen, which is a known inhibitor of P-glycoprotein, was found to voltage-independently inhibit VSOR activity in a number of nonexcitable cells (Zhang et al, 1994;Tominaga et al, 1995b;Meyer and Korbmacher, 1996;Wondergem et al, 2001;Chen et al, 2002;Hélix et al, 2003;Yang et al, 2015) and colonic smooth muscle cells (Dick et al, 1999). In contrast, tamoxifen was ineffective in inhibiting VSOR in neuronal (Leaney et al, 1997;Inoue et al, 2005Zhang et al, 2011) and muscular (Voets et al, 1997) cells as well as in some epithelial cells (Winpenny et al, 1996;Mitchell et al, 1997b) and neutrophils (Ahluwalia, 2008b).…”

Downregulation of LRRC8A protects human ovarian and alveolar carcinoma cells against Cisplatin-induced expression of p53, MDM2, p21Waf1/Cip1, and Caspase-9/-3 activation

“…Furthermore, we found that 18 h Cisplatin exposure resulted in a 2- to 2.5-fold increase in the LRRC8A protein content in A2780WT, whereas its expression in A2780CisR was unaffected ( 44 ). Recent studies performed by Yang and coworkers ( 55 ) have indicated that Cisplatin activates a Cl − current in nasopharyngeal CNE-2Z carcinoma cells, which exhibits properties similar to VRAC (outward rectification, ATP dependence, selectivity sequence of I − > Br − > Cl − > gluconate), and which could be inhibited by the anion channel blocker tamoxifen and extracellular ATP. Studies by Planells-Cases and coworkers ( 36 ) indicate that Cisplatin induced taurine release and the cytotoxic effects of the chemotherapeutic drugs Staurosporine, Cisplatin and Carboplatin are abolished in LRRC8A and LRRC8D knockout HEK cells ( 36 ).…”

Physiology of the volume-sensitive/regulatory anion channel VSOR/VRAC. Part 1: from its discovery and phenotype characterization to the molecular entity identification

“…For example, SITS/DIDS and glibenclamide were found to exhibit voltage-dependent blocking action on VSOR/VRAC currents originally by Kubo & Okada [ 65 ] and Liu et al [ 96 ], respectively. Suramin 6− was also shown to be an open-channel blocker of VSOR/VRAC [ 64 , 72 , 90 , 108 – 111 ]. The open-channel blocking actions are very interesting from the viewpoint of the pore size estimation.…”