Transcriptional repression of human epidermal growth factor receptor 2 by ClC‐3 Cl⁻/H⁺ transporter inhibition in human breast cancer cells

Abstract

Recent studies have indicated that the intracellular concentration of chloride ions (Cl−) regulates gene expression in several types of cells and that Cl− modulators positively or negatively regulate the PI3K/AKT/mammalian target of rapamycin (mTOR) and signal transducer and activator of transcription (STAT)3 signaling pathways. We previously reported that the Ca2+‐activated Cl− channel anoctamine (ANO)1 regulated human epidermal growth factor receptor 2 (HER2) transcription in breast cancer YMB‐1 cells. However, the mechanisms underlying ANO1‐regulated HER2 gene expression have not yet been elucidated. In the present study, we showed the involvement of intracellular organelle ClC‐3 Cl−/H+ transporter in HER2 transcription in breast cancer MDA‐MB‐453 cells. The siRNA‐mediated inhibition of ClC‐3, but not ANO1, markedly repressed HER2 transcription in MDA‐MB‐453 cells. Subsequently, treatments with the AKT inhibitor AZD 5363 and mTOR inhibitor everolimus significantly enhanced HER2 transcription in MDA‐MB‐453 cells, whereas that with the STAT3 inhibitor 5,15‐diphenylporphyrin (5,15‐DPP) inhibited it. AKT and mTOR inhibitors also significantly enhanced HER2 transcription in YMB‐1 cells. The siRNA‐mediated inhibition of ClC‐3 and ANO1 resulted in increased AKT phosphorylation and decreased STAT3 phosphorylation in MDA‐MB‐453 and YMB‐1 cells, respectively. The intracellular Cl− channel protein CLIC1 was expressed in both cells; however, its siRNA‐mediated inhibition did not elicit the transcriptional repression of HER2. Collectively, our results demonstrate that intracellular Cl− regulation by ANO1/ClC‐3 participates in HER2 transcription, mediating the PI3K/AKT/mTOR and/or STAT3 signaling pathway(s) in HER2‐positive breast cancer cells, and support the potential of ANO1/ClC‐3 blockers as therapeutic options for patients with resistance to anti‐HER2 therapies.

The Prognostic Value and Mechanisms of TMEM16A in Human Cancer

“…For example, 1) We know that there are many factors that can promote the high expression of TMEM16A. For example, transcriptional stimulation of the IL4/IL13-Jack-STAT3-STAT6 axis, activation of steroid hormones such as testosterone, histone deacetylase (HDCA), promoter hypomethylation, and downregulation of inhibitory miRNA have been shown to increase the expression of TMEM16A ( Wanitchakool et al, 2014 ; Bill and Alex Gaither, 2017 ; Qu et al, 2014 ; Fujimoto et al, 2018 ). Is it possible to prevent or treat cancer through this stimulus?…”

Contribution of Anoctamins to Cell Survival and Cell Death

“…Thus, removing the cells from their physiological environment, cellular reorganization and pro-mitotic stimulation may all contribute to upregulation of ANO1. Moreover, transcriptional stimulation via the IL4/IL13-Jack-STAT3-STAT6 axis, steroid hormones such as testosterone, activation of histone deacetylase (HDCA), promotor hypo- methylation, as well as downregulation of inhibitory micro-RNAs have been shown to upregulate ANO1 expression (reviewed in [73,74,76,121,122] (Figure 2).…”

ClC-3: A Novel Promising Therapeutic Target for Atherosclerosis

“…35 Moreover, ClC-3 may be a critical subunit or cooperative protein for the assembly of functional proteins or membrane receptors, such as NADPH oxidase 1 (NOX1), 36 protein kinase C (PKC), 37 calcium/calmodulin-dependent protein kinase II (CamKII), 21 matrix metalloproteinase-2 (MMP-2) receptors, 38 Sirtuin 1 (Sirt1), 39 SRY-box transcription factor 2 (SOX2), 40 and serumand glucocorticoid-regulated kinase 1 (SGK1). 41 Notably, angiotensin II (AngII), lipopolysaccharide (LPS), interleukin (IL), endothelin 1 (ET1), transforming growth factor-b1 (TGF-b1), and tumor necrosis factor-a (TNF-a) can promote the ClC-3 expression and stimulate the activation of multiple inflammatory signaling pathways such as nuclear factor kappa B (NF-kB), 36,42 Janus kinase (JAK)-signal transducer and activator of transcription (STAT), 43 and LPS/ Toll-like receptor 4 (TLR4). 44 ClC-3 knockout or inhibition was found to suppress these inflammatory signaling pathways, alleviating the induction of inflammation both in vitro and in vivo.…”