1
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Gründer S, Vanek J, Pissas KP. Acid-sensing ion channels and downstream signalling in cancer cells: is there a mechanistic link? Pflugers Arch 2024; 476:659-672. [PMID: 38175291 PMCID: PMC11006730 DOI: 10.1007/s00424-023-02902-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/05/2024]
Abstract
It is increasingly appreciated that the acidic microenvironment of a tumour contributes to its evolution and clinical outcomes. However, our understanding of the mechanisms by which tumour cells detect acidosis and the signalling cascades that it induces is still limited. Acid-sensing ion channels (ASICs) are sensitive receptors for protons; therefore, they are also candidates for proton sensors in tumour cells. Although in non-transformed tissue, their expression is mainly restricted to neurons, an increasing number of studies have reported ectopic expression of ASICs not only in brain cancer but also in different carcinomas, such as breast and pancreatic cancer. However, because ASICs are best known as desensitizing ionotropic receptors that mediate rapid but transient signalling, how they trigger intracellular signalling cascades is not well understood. In this review, we introduce the acidic microenvironment of tumours and the functional properties of ASICs, point out some conceptual problems, summarize reported roles of ASICs in different cancers, and highlight open questions on the mechanisms of their action in cancer cells. Finally, we propose guidelines to keep ASIC research in cancer on solid ground.
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Affiliation(s)
- Stefan Gründer
- Institute of Physiology, RWTH Aachen University, Pauwelsstraße 30, 52074, Aachen, Germany.
| | - Jakob Vanek
- Institute of Physiology, RWTH Aachen University, Pauwelsstraße 30, 52074, Aachen, Germany
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2
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Zhang Z, Chen M, Zhan W, Chen Y, Wang T, Chen Z, Fu Y, Zhao G, Mao D, Ruan J, Yuan FL. Acid-sensing ion channel 1a modulation of apoptosis in acidosis-related diseases: implications for therapeutic intervention. Cell Death Discov 2023; 9:330. [PMID: 37666823 PMCID: PMC10477349 DOI: 10.1038/s41420-023-01624-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/28/2023] [Accepted: 08/22/2023] [Indexed: 09/06/2023] Open
Abstract
Acid-sensing ion channel 1a (ASIC1a), a prominent member of the acid-sensing ion channel (ASIC) superfamily activated by extracellular protons, is ubiquitously expressed throughout the human body, including the nervous system and peripheral tissues. Excessive accumulation of Ca2+ ions via ASIC1a activation may occur in the acidified microenvironment of blood or local tissues. ASIC1a-mediated Ca2+‑induced apoptosis has been implicated in numerous pathologies, including neurological disorders, cancer, and rheumatoid arthritis. This review summarizes the role of ASIC1a in the modulation of apoptosis via various signaling pathways across different disease states to provide insights for future studies on the underlying mechanisms and development of therapeutic strategies.
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Affiliation(s)
- Zhenyu Zhang
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Minnan Chen
- Nantong First People's Hospital, Nantong, 226001, China
| | - Wenjing Zhan
- The Key Laboratory of Anti-Inflammatory and Immune Medicine, Anhui Medical University, Hefei, 230032, China
| | - Yuechun Chen
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Tongtong Wang
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Zhonghua Chen
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Yifei Fu
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Gang Zhao
- Orthopaedic Institute, Wuxi 9th People's Hospital Affiliated to Soochow University, Wuxi, 214062, China
| | - Dong Mao
- Orthopaedic Institute, Wuxi 9th People's Hospital Affiliated to Soochow University, Wuxi, 214062, China.
| | - Jingjing Ruan
- Nantong First People's Hospital, Nantong, 226001, China.
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, People's Republic of China.
| | - Feng-Lai Yuan
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China.
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3
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Acid-sensing ion channel 1: potential therapeutic target for tumor. Biomed Pharmacother 2022; 155:113835. [DOI: 10.1016/j.biopha.2022.113835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/25/2022] [Accepted: 10/06/2022] [Indexed: 11/20/2022] Open
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4
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King P, Wan J, Guo AA, Guo S, Jiang Y, Liu M. Regulation of gliomagenesis and stemness through acid sensor ASIC1a. Int J Oncol 2021; 59:82. [PMID: 34515325 PMCID: PMC8448544 DOI: 10.3892/ijo.2021.5262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/28/2021] [Indexed: 01/29/2023] Open
Abstract
Glioblastoma multiforme (GBM) is the most prevalent and aggressive type of adult gliomas. Despite intensive therapy including surgery, radiation, and chemotherapy, invariable tumor recurrence occurs, which suggests that glioblastoma stem cells (GSCs) render these tumors persistent. Recently, the induction of GSC differentiation has emerged as an alternative method to treat GBM, and most of the current studies aim to convert GSCs to neurons by a combination of transcriptional factors. As the tumor microenvironment is typically acidic due to increased glycolysis and consequently leads to an increased production of lactic acid in tumor cells, in the present study, the role of acid‑sensing ion channel 1a (ASIC1a), an acid sensor, was explored as a tumor suppressor in gliomagenesis and stemness. The bioinformatics data from The Cancer Genome Atlas revealed that ASIC1 expression levels in GBM tumor tissues were lower than those in normal brain, and glioma patients with high ASIC1 expression had longer survival than those with low ASIC1 expression. Our immunohistochemistry data from tissue microarray revealed that ASIC1a expression was negatively associated with glioma grading. Functional studies revealed that the downregulation of ASIC1a promoted glioma cell proliferation and invasion, while upregulation of ASIC1a inhibited their proliferation and invasion. Furthermore, ASIC1a suppressed growth and proliferation of glioma cells through G1/S arrest and apoptosis induction. Mechanistically, ASIC1a negatively modulated glioma stemness via inhibition of the Notch signaling pathway and GSC markers CD133 and aldehyde dehydrogenase 1. ASIC1a is a tumor suppressor in gliomagenesis and stemness and may serve as a promising prognostic biomarker and target for GBM patients.
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Affiliation(s)
- Pendelton King
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - Jingwei Wan
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, GA 30310, USA
- Department of Neurosurgery, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Alyssa Aihui Guo
- Department of Biomedical Sciences, School of Medicine Greenville, University of South Carolina, Greenville, SC 29605, USA
| | - Shanchun Guo
- Department of Chemistry, Xavier University, New Orleans, LA 70125, USA
| | - Yugang Jiang
- Department of Neurosurgery, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Mingli Liu
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, GA 30310, USA
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5
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Abstract
The microenvironment of solid tumors is often acidic due to poor vascular perfusion, regional hypoxia, and increased glycolytic activity of tumor cells. Although acidosis is harmful to most types of cells, tumor cells seem well adapted to such harsh conditions. Moreover, overwhelming evidence indicates that tumor cells are more invasive and more aggressive in acidic conditions by a cascade of cell signaling and upregulation of oncogenic gene expression. Therefore, how extracellular acidic signals are transduced to the cytoplasm and then into the nucleus is an interesting topic to many cancer researchers. In this review, we update on the recent advances in acidosis-induced tumorigenesis through the acid-sensing ion channels (ASICs) and activation of cell signaling.
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Affiliation(s)
- Liu Yang
- Key Laboratory of Tumor Molecular Diagnosis and Individualized Medicine of Zhejiang Province, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, 310014, Zhejiang, P.R. China
| | - Xiaoge Hu
- Key Laboratory of Tumor Molecular Diagnosis and Individualized Medicine of Zhejiang Province, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, 310014, Zhejiang, P.R. China.,Cancer Institute and Department of Pharmacology/Toxicology, University of Mississippi Medical Center, Jackson, MS, USA
| | - Yin-Yuan Mo
- Cancer Institute and Department of Pharmacology/Toxicology, University of Mississippi Medical Center, Jackson, MS, USA.
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6
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Glitsch M. Mechano- and pH-sensing convergence on Ca 2+-mobilising proteins - A recipe for cancer? Cell Calcium 2019; 80:38-45. [PMID: 30952068 DOI: 10.1016/j.ceca.2019.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 03/27/2019] [Accepted: 03/27/2019] [Indexed: 02/06/2023]
Abstract
Alterations in the (bio)chemical and physical microenvironment of cells accompany and often promote disease formation and progression. This is particularly well established for solid cancers, which are typically stiffer than the healthy tissue in which they arise, and often display profound acidification of their interstitial fluid. Cell surface receptors can sense changes in the mechanical and (bio)chemical properties of the surrounding extracellular matrix and fluid, and signalling through these receptors is thought to play a key role in disease development and advancement. This review will look at ion channels and G protein coupled receptors that are activated by mechanical cues and extracellular acidosis, and stimulation of which results in increases in intracellular Ca2+ concentrations. Cellular Ca2+ levels are dysregulated in cancer as well as cancer-associated cells, and mechano- and proton-sensing proteins likely contribute to these aberrant intracellular Ca2+ signals, making them attractive targets for therapeutic intervention.
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Affiliation(s)
- Maike Glitsch
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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7
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Tian Y, Bresenitz P, Reska A, El Moussaoui L, Beier CP, Gründer S. Glioblastoma cancer stem cell lines express functional acid sensing ion channels ASIC1a and ASIC3. Sci Rep 2017; 7:13674. [PMID: 29057936 PMCID: PMC5651884 DOI: 10.1038/s41598-017-13666-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 09/29/2017] [Indexed: 12/18/2022] Open
Abstract
Acidic microenvironment is commonly observed in tumour tissues, including glioblastoma (GBM), the most aggressive and lethal brain tumour in adults. Acid sensing ion channels (ASICs) are neuronal voltage-insensitive sodium channels, which are sensors of extracellular protons. Here we studied and functionally characterized ASICs in two primary glioblastoma stem cell lines as cell culture models. We detected transcripts of the ACCN2 and ACCN3 genes, coding for ASIC1 and ASIC3, respectively, but not transcripts of ACCN1 (coding for ASIC2). Available microarray data confirmed that ACCN1 is downregulated in glioma. Western blotting confirmed expression of ASIC1 and ASIC3, the most proton-sensitive ASICs, in both GBM cell lines. We characterized ASICs functionally using whole-cell patch clamp and detected different types of acid-sensitive currents. Some of these currents had kinetics typical for ASICs and were sensitive to specific toxin inhibitors of ASIC1a or ASIC3, demonstrating that the GBM cell lines express functional ASIC1a and ASIC3 that may enable GBM cells to sensitively detect extracellular pH in a tumour tissue. Microarray data revealed that expression of ACCN2 and ACCN3 is associated with improved survival of patients suffering from gliomas, suggesting that preserved susceptibility to extracellular pH may impair tumour growth.
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Affiliation(s)
- Yuemin Tian
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, D-52074, Aachen, Germany
| | - Pia Bresenitz
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, D-52074, Aachen, Germany
| | - Anna Reska
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, D-52074, Aachen, Germany
| | - Laila El Moussaoui
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, D-52074, Aachen, Germany
| | - Christoph Patrick Beier
- Department of Neurology, RWTH Aachen University, Pauwelsstrasse 30, D-52074, Aachen, Germany.,Department of Neurology and Department of Clinical Research, Odense University Hospital and University of Southern Denmark, Sdr. Boulevard 20, 5000 Odense C, Denmark
| | - Stefan Gründer
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, D-52074, Aachen, Germany.
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8
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Chen B, Liu J, Ho TT, Ding X, Mo YY. ERK-mediated NF-κB activation through ASIC1 in response to acidosis. Oncogenesis 2016; 5:e279. [PMID: 27941930 PMCID: PMC5177778 DOI: 10.1038/oncsis.2016.81] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 10/30/2016] [Accepted: 11/03/2016] [Indexed: 12/16/2022] Open
Abstract
Acidic microenvironment is a common feature of solid tumors. We have previously shown that neuron specific acid-sensing ion channel 1 (ASIC1) is expressed in breast cancer, and it is responsible for acidosis-induced cellular signaling through AKT, leading to nuclear factor-κB (NF-κB) activation, and cell invasion and metastasis. However, AKT is frequently activated in cancer. Thus, a key question is whether ASIC1-mediated cell signaling still takes place in the cancer cells carrying constitutively active AKT. In the present study, we show that among four prostate cancer cell lines tested, 22Rv1 cells express the highest level of phosphorylated AKT that is not impacted by acidosis. However, acidosis can still induce NF-κB activation during which extracellular signal-regulated kinase (ERK) serves as an alternative pathway for ASIC-mediated cell signaling. Inhibition of ERK by chemical inhibitors or small interfering RNAs suppresses the acidosis-induced NF-κB activity through regulation of the inhibitory subunit IκBα phosphorylation. Furthermore, suppression of ASIC1-mediated generation of reactive oxygen species (ROS) by ROS scavengers, such as glutathione or N-acetyl-cysteine causes a decrease in ERK phosphorylation and degradation of IκBα. Finally, ASIC1 is upregulated in a subset of prostate cancer cases and ASIC1 knockout by CRISPR/Cas9 significantly suppresses cell invasion, and castration resistance both in vitro and in vivo. Together, these results support the significance of ASIC1-ROS-ERK-IκBα-NF-κB axis in prostate tumorigenesis, especially in the constitutively active AKT background.
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Affiliation(s)
- B Chen
- Department of Urology, Affiliated Hospital of Jiangsu University, Zhenjiang, China.,Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA
| | - J Liu
- Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Emergency Medicine, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - T-T Ho
- Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Radiation Oncology, University of Mississippi Medical Center, Jackson, MS, USA
| | - X Ding
- Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA.,College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, China
| | - Y-Y Mo
- Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Pharmacology/Toxicology, University of Mississippi Medical Center, Jackson, MS, USA
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9
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Gupta SC, Singh R, Asters M, Liu J, Zhang X, Pabbidi MR, Watabe K, Mo YY. Regulation of breast tumorigenesis through acid sensors. Oncogene 2016; 35:4102-11. [PMID: 26686084 PMCID: PMC6450404 DOI: 10.1038/onc.2015.477] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 10/01/2015] [Accepted: 11/06/2015] [Indexed: 12/18/2022]
Abstract
The low extracellular pH in the microenvironment has been shown to promote tumor growth and metastasis; however, the underlying mechanism is poorly understood. Particularly, little is known how the tumor cell senses the acidic signal to activate the acidosis-mediated signaling. In this study, we show that breast cancer cells express acid-sensing ion channel 1 (ASIC1), a proton-gated cation channel primarily expressed in the nervous system. RNA interference, knockout and rescue experiments demonstrate a critical role for ASIC1 in acidosis-induced reactive oxidative species and NF-κB activation, two key events for tumorigenesis. Mechanistically, ASIC1 is required for acidosis-mediated signaling through calcium influx. We show that as a cytoplasmic membrane protein, ASIC1 is also associated with mitochondria, suggesting that ASIC1 may regulate mitochondrial calcium influx. Importantly, interrogation of the Cancer Genome Atlas breast invasive carcinoma data set indicates that alterations of ASIC1 alone or combined with other 4 ASIC genes are significantly correlated with poor patient survival. Furthermore, ASIC1 inhibitors cause a significant reduction of tumor growth and tumor load. Together, these results suggest that ASIC1 contributes to breast cancer pathogenesis in response to acidic tumor microenvironments, and ASIC1 may serve as a prognostic marker and a therapeutic target for breast cancer.
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Affiliation(s)
- S C Gupta
- Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, MS, USA
| | - R Singh
- Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, MS, USA
| | - M Asters
- Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA
| | - J Liu
- Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA
| | - X Zhang
- Center of Biostatistics and Bioinformatics, University of Mississippi Medical Center, Jackson, MS, USA
| | - M R Pabbidi
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, USA
| | - K Watabe
- Department of Cancer Biology, Wake Forest University School of Medicine, Winston Salem, NC, USA
| | - Y-Y Mo
- Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, USA
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10
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Boursi B, Han HJ, Haynes K, Mamtani R, Yang YX. Ion channel blockers and glioblastoma risk and outcome: a nested case-control and retrospective cohort studies. Pharmacoepidemiol Drug Saf 2016; 25:1179-1185. [PMID: 27384764 DOI: 10.1002/pds.4054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 05/16/2016] [Accepted: 05/30/2016] [Indexed: 11/08/2022]
Abstract
PURPOSE Mutations in ion channels are common among patients with glioblastoma multiforme (GBM) and promote cell migration and invasion. We sought to evaluate the association between the use of specific ion channel blockers such as digoxin, amiodarone, diltiazem and verapamil and GBM risk and survival. METHODS We conducted a nested case-control study in a large primary care database from the UK. Cases were defined as all individuals with incident diagnosis of GBM during follow-up. For each case, up to four controls were selected using incidence density sampling. The primary exposure of interest was active treatment with each of the four ion channel blockers. We used conditional logistic regression to estimate odds ratios and 95% confidence interval (CI) for the association between ion channel blocker use and GBM risk. We then performed a Cox regression analysis among those diagnosed with GBM in order to evaluate the association between use of ion channel blockers and overall survival. Both analyses were adjusted to common confounders. RESULTS The study included 1076 cases and 4253 matched controls. There was no statistically significant difference between cases and controls in cardiac and metabolic risk factors. There was no change in GBM risk in active users of ion channel blockers compared with non-users. Among patients with GBM, active users of amiodarone had worse survival compared with never users with an HR of 4.41 (95%CI 1.95-9.96). There was no statistically significant change in survival among diltiazem, verapamil or digoxin users. CONCLUSION Treatment with specific ion channel blockers was not associated with the risk of GBM but was associated with worse survival in patients with GBM. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Ben Boursi
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA.,Tel-Aviv University, Tel-Aviv, Israel
| | - Harry J Han
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kevin Haynes
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ronac Mamtani
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
| | - Yu-Xiao Yang
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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11
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Simon OJ, Müntefering T, Grauer OM, Meuth SG. The role of ion channels in malignant brain tumors. J Neurooncol 2015; 125:225-35. [PMID: 26334315 DOI: 10.1007/s11060-015-1896-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Accepted: 08/14/2015] [Indexed: 12/15/2022]
Abstract
Malignant gliomas are the most common primary brain tumors and have poor clinical prognosis, despite multimodal therapeutic strategies. In recent years, ion channels have emerged as major players in tumor pathophysiology regarding all hallmarks of cancer. Since ion channels are easily accessible structures, they may prove to be effective targets for canner therapy, although their broad expression pattern and role in physiological processes should be taken into consideration. This review summarizes the current knowledge on the role of ion channels in the pathophysiology of malignant gliomas, especially glioblastoma, and evaluates their potential role in targeted antiglioma therapy.
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Affiliation(s)
- Ole J Simon
- Department of Neurology, University of Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany.
| | - Thomas Müntefering
- Department of Neurology, University of Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany
| | - Oliver M Grauer
- Department of Neurology, University of Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany
| | - Sven G Meuth
- Department of Neurology, University of Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany
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12
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Rooj AK, Liu Z, McNicholas CM, Fuller CM. Physical and functional interactions between a glioma cation channel and integrin-β1 require α-actinin. Am J Physiol Cell Physiol 2015; 309:C308-19. [PMID: 26108662 DOI: 10.1152/ajpcell.00036.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 06/17/2015] [Indexed: 11/22/2022]
Abstract
Major plasma membrane components of the tumor cell, ion channels, and integrins play crucial roles in metastasis. Glioma cells express an amiloride-sensitive nonselective cation channel composed of acid-sensing ion channel (ASIC)-1 and epithelial Na(+) channel (ENaC) α- and γ-subunits. Inhibition of this channel is associated with reduced cell migration and proliferation. Using the ASIC-1 subunit as a reporter for the channel complex, we found a physical and functional interaction between this channel and integrin-β1. Short hairpin RNA knockdown of integrin-β1 attenuated the amiloride-sensitive current, which was due to loss of surface expression of ASIC-1. In contrast, upregulation of membrane expression of integrin-β1 increased the surface expression of ASIC-1. The link between the amiloride-sensitive channel and integrin-β1 was mediated by α-actinin. Downregulation of α-actinin-1 or -4 attenuated the amiloride-sensitive current. Mutation of the putative binding site for α-actinin on the COOH terminus of ASIC-1 reduced the membrane localization of ASIC-1 and also resulted in attenuation of the amiloride-sensitive current. Our data suggest a novel interaction between the amiloride-sensitive glioma cation channel and integrin-β1, mediated by α-actinin. This interaction may form a mechanism by which channel activity can regulate glioma cell proliferation and migration.
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Affiliation(s)
- Arun K Rooj
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Zhiyong Liu
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Carmel M McNicholas
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Catherine M Fuller
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
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13
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Ouadid-Ahidouch H, Rodat-Despoix L, Matifat F, Morin G, Ahidouch A. DNA methylation of channel-related genes in cancers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2621-8. [PMID: 25703813 DOI: 10.1016/j.bbamem.2015.02.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 02/04/2015] [Accepted: 02/12/2015] [Indexed: 12/31/2022]
Abstract
DNA methylation at CpG sites is an epigenetic mechanism that regulates cellular gene expression. In cancer cells, aberrant methylation is correlated with the abnormalities in expression of genes that are known to be involved in the particular characteristics of cancer cells such as proliferation, apoptosis, migration or invasion. During the past 30 years, accumulating data have definitely convinced the scientific community that ion channels are involved in cancerogenesis and cancer properties. As they are situated at the cell surface, they might be prime targets in the development of new therapeutic strategies besides their potential use as prognostic factors. Despite the progress in our understanding of the remodeling of ion channels in cancer cells, the molecular mechanisms underlying their over- or down-expression remained enigmatic. In this review, we aimed to summarize the available data on gene promoter methylation of ion channels and to investigate their clinical significance as novel biomarkers in cancer. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.
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Affiliation(s)
- Halima Ouadid-Ahidouch
- UFR Sciences, EA 4667, Laboratory of Cell and Molecular Physiology, University of Picardie Jules Verne, SFR CAP-SANTE (FED 4231), Amiens, France.
| | - Lise Rodat-Despoix
- UFR Sciences, EA 4667, Laboratory of Cell and Molecular Physiology, University of Picardie Jules Verne, SFR CAP-SANTE (FED 4231), Amiens, France
| | - Fabrice Matifat
- UFR Sciences, EA 4667, Laboratory of Cell and Molecular Physiology, University of Picardie Jules Verne, SFR CAP-SANTE (FED 4231), Amiens, France
| | - Gilles Morin
- EA 4666 and Department of Molecular and Clinical Genetics, Amiens University Hospital, University of Picardie Jules Verne, Amiens, France
| | - Ahmed Ahidouch
- UFR Sciences, EA 4667, Laboratory of Cell and Molecular Physiology, University of Picardie Jules Verne, SFR CAP-SANTE (FED 4231), Amiens, France; Department of Biology, Faculty of Sciences, Ibn Zohr University, Agadir Morocco
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14
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SUN XU, ZHAO DAN, LI YONGLI, SUN YING, LEI XUHUI, ZHANG JIANING, WU MINGMING, LI RUIYAN, ZHAO ZHEFENG, ZHANG ZHIREN, JIANG CHUANLU. Regulation of ASIC1 by Ca2+/calmodulin-dependent protein kinase II in human glioblastoma multiforme. Oncol Rep 2013; 30:2852-8. [DOI: 10.3892/or.2013.2777] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 09/13/2013] [Indexed: 11/06/2022] Open
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15
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Abstract
Hypoxia represents the lack of oxygen below the basic level, and the range of known channels related to hypoxia is continually increasing. Since abnormal hypoxia initiates pathological processes in numerous diseases via, to a great degree, producing acidic microenvironment, the significance of these channels in this environment has, until now, remained completely unknown. However, recent discovery of acid-sensing ion channels (ASICs) have enhanced our understanding of the hypoxic channelome. They belong to the degenerin/epithelial Na (+) channel family and function once extracellular pH decreases to a certain level. So does the ratiocination emerge that ASICs participate in many hypoxia-induced pathological processes, including pain, apoptosis, malignancy, which all appear to involve them. Since evidence suggests that activity of ASICs is altered under pathological hypoxia, future studies are needed to deeply explore the relationship between ASICs and hypoxia, which may provide a progressive understanding of hypoxic effects in cancer, arthritis, intervertebral disc degeneration, ischemic brain injury and so on.
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Affiliation(s)
- Guo Yingjun
- Department of Basic Medicine; Qilu Hospital; Shandong University; Ji'nan, Shandong Province, PR China
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16
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Zha XM. Acid-sensing ion channels: trafficking and synaptic function. Mol Brain 2013; 6:1. [PMID: 23281934 PMCID: PMC3562204 DOI: 10.1186/1756-6606-6-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 12/20/2012] [Indexed: 01/05/2023] Open
Abstract
Extracellular acidification occurs in the brain with elevated neural activity, increased metabolism, and neuronal injury. This reduction in pH can have profound effects on brain function because pH regulates essentially every single biochemical reaction. Therefore, it is not surprising to see that Nature evolves a family of proteins, the acid-sensing ion channels (ASICs), to sense extracellular pH reduction. ASICs are proton-gated cation channels that are mainly expressed in the nervous system. In recent years, a growing body of literature has shown that acidosis, through activating ASICs, contributes to multiple diseases, including ischemia, multiple sclerosis, and seizures. In addition, ASICs play a key role in fear and anxiety related psychiatric disorders. Several recent reviews have summarized the importance and therapeutic potential of ASICs in neurological diseases, as well as the structure-function relationship of ASICs. However, there is little focused coverage on either the basic biology of ASICs or their contribution to neural plasticity. This review will center on these topics, with an emphasis on the synaptic role of ASICs and molecular mechanisms regulating the spatial distribution and function of these ion channels.
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Affiliation(s)
- Xiang-ming Zha
- Department of Cell Biology and Neuroscience, College of Medicine, University of South Alabama, 307 University Blvd, MSB1201, Mobile, AL 36688, USA.
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17
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Ruggieri P, Mangino G, Fioretti B, Catacuzzeno L, Puca R, Ponti D, Miscusi M, Franciolini F, Ragona G, Calogero A. The inhibition of KCa3.1 channels activity reduces cell motility in glioblastoma derived cancer stem cells. PLoS One 2012; 7:e47825. [PMID: 23110108 PMCID: PMC3478269 DOI: 10.1371/journal.pone.0047825] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 09/17/2012] [Indexed: 02/04/2023] Open
Abstract
In the present study we evaluated the expression of the intermediate conductance calcium-activated potassium (KCa3.1) channel in human glioblastoma stem-like cells (CSCs) and investigated its role in cell motility. While the KCa3.1 channel is not expressed in neuronal- and glial-derived tissues of healthy individuals, both the KCa3.1 mRNA and protein are present in the glioblastoma tumor population, and are significantly enhanced in CSCs derived from both established cell line U87MG and a primary cell line, FCN9. Consistent with these data, voltage-independent and TRAM-34 sensitive potassium currents imputable to the KCa3.1 channel were recorded in the murine GL261 cell line and several primary human glioblastoma cells lines. Moreover, a significantly higher KCa3.1 current was recorded in U87MG-CD133 positive cells as compared to the U87MG-CD133 negative subpopulation. Further, we found that the tumor cell motility is strongly associated with KCa3.1 channel expression. Blockade of the KCa3.1 channel with the specific inhibitor TRAM-34 has in fact a greater impact on the motility of CSCs (reduction of 75%), which express a high level of KCa3.1 channel, than on the FCN9 parental population (reduction of 32%), where the KCa3.1 channel is expressed at lower level. Similar results were also observed with the CSCs derived from U87MG. Because invasion of surrounding tissues is one of the main causes of treatment failure in glioblastoma, these findings can be relevant for future development of novel cancer therapeutic drugs.
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Affiliation(s)
- Paola Ruggieri
- Department of Medical-surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy
| | - Giorgio Mangino
- Department of Medical-surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy
| | - Bernard Fioretti
- Department of Cellular and Environmental Biology, University of Perugia, Perugia, Italy
| | - Luigi Catacuzzeno
- Department of Cellular and Environmental Biology, University of Perugia, Perugia, Italy
| | - Rosa Puca
- Department of Medical-surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy
| | - Donatella Ponti
- Department of Medical-surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy
| | - Massimo Miscusi
- Department of Medical-surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy
| | - Fabio Franciolini
- Department of Cellular and Environmental Biology, University of Perugia, Perugia, Italy
| | - Giuseppe Ragona
- Department of Medical-surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy
| | - Antonella Calogero
- Department of Medical-surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy
- * E-mail:
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18
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Rooj AK, McNicholas CM, Bartoszewski R, Bebok Z, Benos DJ, Fuller CM. Glioma-specific cation conductance regulates migration and cell cycle progression. J Biol Chem 2011; 287:4053-65. [PMID: 22130665 DOI: 10.1074/jbc.m111.311688] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we have investigated the role of a glioma-specific cation channel assembled from subunits of the Deg/epithelial sodium channel (ENaC) superfamily, in the regulation of migration and cell cycle progression in glioma cells. Channel inhibition by psalmotoxin-1 (PcTX-1) significantly inhibited migration and proliferation of D54-MG glioma cells. Both PcTX-1 and benzamil, an amiloride analog, caused cell cycle arrest of D54-MG cells in G(0)/G(1) phases (by 30 and 40%, respectively) and reduced cell accumulation in S and G(2)/M phases after 24 h of incubation. Both PcTX-1 and benzamil up-regulated expression of cyclin-dependent kinase inhibitor proteins p21(Cip1) and p27(Kip1). Similar results were obtained in U87MG and primary glioblastoma multiforme cells maintained in primary culture and following knockdown of one of the component subunits, ASIC1. In contrast, knocking down δENaC, which is not a component of the glioma cation channel complex, had no effect on cyclin-dependent kinase inhibitor expression. Phosphorylation of ERK1/2 was also inhibited by PcTX-1, benzamil, and knockdown of ASIC1 but not δENaC in D54MG cells. Our data suggest that a specific cation conductance composed of acid-sensing ion channels and ENaC subunits regulates migration and cell cycle progression in gliomas.
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Affiliation(s)
- Arun K Rooj
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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19
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Molenaar RJ. Ion channels in glioblastoma. ISRN NEUROLOGY 2011; 2011:590249. [PMID: 22389824 PMCID: PMC3263536 DOI: 10.5402/2011/590249] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 09/19/2011] [Indexed: 11/23/2022]
Abstract
Glioblastoma is the most common primary brain tumor with the most dismal prognosis. It is characterized by extensive invasion, migration, and angiogenesis. Median survival is only 15 months due to this behavior, rendering focal surgical resection ineffective and adequate radiotherapy impossible. At this moment, several ion channels have been implicated in glioblastoma proliferation, migration, and invasion. This paper summarizes studies on potassium, sodium, chloride, and calcium channels of glioblastoma. It provides an up-to-date overview of the literature that could ultimately lead to new therapeutic targets.
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Affiliation(s)
- Remco J Molenaar
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
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20
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Zhao Y, Cai X, Ye T, Huo J, Liu C, Zhang S, Cao P. Analgesic-antitumor peptide inhibits proliferation and migration of SHG-44 human malignant glioma cells. J Cell Biochem 2011; 112:2424-34. [DOI: 10.1002/jcb.23166] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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21
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Arvind S, Arivazhagan A, Santosh V, Chandramouli BA. Differential expression of a novel voltage gated potassium channel – Kv 1.5 in astrocytomas and its impact on prognosis in glioblastoma. Br J Neurosurg 2011; 26:16-20. [DOI: 10.3109/02688697.2011.583365] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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22
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Cuddapah VA, Sontheimer H. Ion channels and transporters [corrected] in cancer. 2. Ion channels and the control of cancer cell migration. Am J Physiol Cell Physiol 2011; 301:C541-9. [PMID: 21543740 DOI: 10.1152/ajpcell.00102.2011] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A hallmark of high-grade cancers is the ability of malignant cells to invade unaffected tissue and spread disease. This is particularly apparent in gliomas, the most common and lethal type of primary brain cancer affecting adults. Migrating cells encounter restricted spaces and appear able to adjust their shape to accommodate to narrow extracellular spaces. A growing body of work suggests that cell migration/invasion is facilitated by ion channels and transporters. The emerging concept is that K(+) and Cl(-) function as osmotically active ions, which cross the plasma membrane in concert with obligated water thereby adjusting a cell's shape and volume. In glioma cells Na(+)-K(+)-Cl(-) cotransporters (NKCC1) actively accumulate K(+) and Cl(-), establishing a gradient for KCl efflux. Ca(2+)-activated K(+) channels and voltage-gated Cl(-) channels are largely responsible for effluxing KCl promoting hydrodynamic volume changes. In other cancers, different K(+) or even Na(+) channels may function in concert with a variety of Cl(-) channels to support similar volume changes. Channels involved in migration are frequently regulated by Ca(2+) signaling, most likely coupling extracellular stimuli to cell migration. Importantly, the inhibition of ion channels and transporters appears to be clinically relevant for the treatment of cancer. Recent preclinical data indicates that inhibition of NKCC1 with an FDA-approved drug decreases neoplastic migration. Additionally, ongoing clinical trials demonstrate that an inhibitor of chloride channels may be a therapy for the treatment of gliomas. Data reviewed here strongly indicate that ion channels are a promising target for the development of novel therapeutics to combat cancer.
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Affiliation(s)
- Vishnu Anand Cuddapah
- Department of Neurobiology and Center for Glial Biology in Medicine, University of Alabama at Birmingham, USA
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23
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Clark EB, Jovov B, Rooj AK, Fuller CM, Benos DJ. Proteolytic cleavage of human acid-sensing ion channel 1 by the serine protease matriptase. J Biol Chem 2010; 285:27130-27143. [PMID: 20601429 DOI: 10.1074/jbc.m110.153213] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Acid-sensing ion channel 1 (ASIC1) is a H(+)-gated channel of the amiloride-sensitive epithelial Na(+) channel (ENaC)/degenerin family. ASIC1 is expressed mostly in the central and peripheral nervous system neurons. ENaC and ASIC function is regulated by several serine proteases. The type II transmembrane serine protease matriptase activates the prototypical alphabetagammaENaC channel, but we found that matriptase is expressed in glioma cells and its expression is higher in glioma compared with normal astrocytes. Therefore, the goal of this study was to test the hypothesis that matriptase regulates ASIC1 function. Matriptase decreased the acid-activated ASIC1 current as measured by two-electrode voltage clamp in Xenopus oocytes and cleaved ASIC1 expressed in oocytes or CHO K1 cells. Inactive S805A matriptase had no effect on either the current or the cleavage of ASIC1. The effect of matriptase on ASIC1 was specific, because it did not affect the function of ASIC2 and no matriptase-specific ASIC2 fragments were detected in oocytes or in CHO cells. Three matriptase recognition sites were identified in ASIC1 (Arg-145, Lys-185, and Lys-384). Site-directed mutagenesis of these sites prevented matriptase cleavage of ASIC1. Our results show that matriptase is expressed in glioma cells and that matriptase specifically cleaves ASIC1 in heterologous expression systems.
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Affiliation(s)
- Edlira B Clark
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Biljana Jovov
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Arun K Rooj
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Catherine M Fuller
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Dale J Benos
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294.
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24
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Liu F, Zhang M, Tang ZQ, Lu YG, Chen L. Inhibitory effects of amiloride on the current mediated by native GABA(A) receptors in cultured neurons of rat inferior colliculus. Clin Exp Pharmacol Physiol 2009; 37:435-40. [PMID: 19878215 DOI: 10.1111/j.1440-1681.2009.05325.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. The diuretic amiloride is known to modulate the activity of several types of ion channels and membrane receptors in addition to its inhibitory effects on many ion transport systems. However, the effects of amiloride on some important ion channels and receptors, such as GABA(A) receptors, in the central nervous system have not been characterized. 2. In the present study, we investigated the functional action of amiloride on native GABA(A) receptors in cultured neurons of rat inferior colliculus using whole-cell patch-clamp recordings. 3. Amiloride reversibly inhibited the amplitude of the GABA-induced current (I(GABA)) in a concentration-dependent manner (IC(50) 454 +/- 24 micromol/L) under conditions of voltage-clamp with a holding potential at -60 mV. The inhibition depended on drug application mode and was independent of membrane potential. Amiloride did not change the reversal potential of I(GABA). Moreover, amiloride induced a parallel right-ward shift in the concentration-response curve for I(GABA) without altering the maximal value and Hill coefficient. 4. The present study shows that amiloride competitively inhibits the current mediated by native GABA(A) receptors in the brain region, probably via a direct action on GABA-binding sites on the receptor. The findings suggest that the functional actions of amiloride on GABA(A) receptors may result in possible side-effects on the central nervous system in the case of direct application of this drug into the cerebrospinal fluid for treatment of diseases such as brain tumours.
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Affiliation(s)
- Feng Liu
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, China
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25
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Shamji MF, Fric-Shamji EC, Benoit BG. Brain tumors and epilepsy: pathophysiology of peritumoral changes. Neurosurg Rev 2009; 32:275-84; discussion 284-6. [PMID: 19205766 DOI: 10.1007/s10143-009-0191-7] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 10/15/2008] [Accepted: 12/18/2008] [Indexed: 02/07/2023]
Abstract
Epilepsy commonly develops among patients with brain tumors, frequently even as the presenting symptom, and such patients consequently experience substantial morbidity from both the seizures and the underlying disease. At clinical presentation, these seizures are most commonly focal with secondary generalization and conventional medical management is often met with less efficacy. The molecular pathophysiology of these seizures is being elucidated with findings that both the tumoral and peritumoral microenvironments may exhibit epileptogenic phenotypes owing to disordered neuronal connectivity and regulation, impaired glial cell function, and the presence of altered vascular supply and permeability. Neoplastic tissue can itself be the initiation site of seizure activity, particularly for tumors arising from neuronal cell lines, such as gangliogliomas or dysembryoblastic neuroepithelial tumors. Conversely, a growing intracranial lesion can both structurally and functionally alter the surrounding brain tissue with edema, vascular insufficiency, inflammation, and release of metabolically active molecules, hence also promoting seizure activity. The involved mechanisms are certain to be multifactorial and depend on specific tumor histology, integrity of the blood brain barrier, and characteristics of the peritumoral environment. Understanding these changes that underlie tumor-related epilepsy may have roles in both optimal medical management for the seizure symptom and optimal surgical objective and management of the underlying disease.
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Affiliation(s)
- Mohammed F Shamji
- Division of Neurosurgery, The Ottawa Hospital, Civic Campus, C2, 1053 Carling Avenue, Ottawa, ON K1Y4E9, Canada.
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26
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Bashari E, Qadri YJ, Zhou ZH, Kapoor N, Anderson SJ, Meltzer RH, Fuller CM, Benos DJ. Two PKC consensus sites on human acid-sensing ion channel 1b differentially regulate its function. Am J Physiol Cell Physiol 2008; 296:C372-84. [PMID: 19091960 DOI: 10.1152/ajpcell.00200.2008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Human acid-sensing ion channel 1b (hASIC1b) is a H(+)-gated amiloride-sensitive cation channel. We have previously shown that glioma cells exhibit an amiloride-sensitive cation conductance. Amiloride and the ASIC1 blocker psalmotoxin-1 decrease the migration and proliferation of glioma cells. PKC also abolishes the amiloride-sensitive conductance of glioma cells and inhibits hASIC1b open probability in planar lipid bilayers. In addition, hASIC1b's COOH terminus has been shown to interact with protein interacting with C kinase (PICK)1, which targets PKC to the plasma membrane. Therefore, we tested the hypothesis that PKC regulation of hASIC1b at specific PKC consensus sites inhibits hASIC1b function. We mutated three consensus PKC phosphorylation sites (T26, S40, and S499) in hASIC1b to alanine, to prevent phosphorylation, and to glutamic acid or aspartic acid, to mimic phosphorylation. Our data suggest that S40 and S499 are critical sites mediating the modulation of hASIC1b by PKC. We expressed mutant hASIC1b constructs in Xenopus oocytes and measured acid-activated currents by two-electrode voltage clamp. T26A and T26E did not exhibit acid-activated currents. S40A was indistinguishable from wild type (WT), whereas S40E, S499A, and S499D currents were decreased. The PKC activators PMA and phorbol 12,13-dibutyrate inhibited WT hASIC1b and S499A, and PMA had no effect on S40A or on WT hASIC1b in oocytes pretreated with the PKC inhibitor chelerythrine. Chelerythrine inhibited WT hASIC1b and S40A but had no effect on S499A or S40A/S499A. PKC activators or the inhibitor did not affect the surface expression of WT hASIC1b. These data show that the two PKC consensus sites S40 and S499 differentially regulate hASIC1b and mediate the effects of PKC activation or PKC inhibition on hASIC1b. This will result in a deeper understanding of PKC regulation of this channel in glioma cells, information that may help in designing potentially beneficial therapies in their treatment.
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Affiliation(s)
- Edlira Bashari
- Dept. of Physiology and Biophysics, Univ. of Alabama at Birmingham, Birmingham, AL 35294, USA
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27
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Ross SB, Fuller CM, Bubien JK, Benos DJ. Amiloride-sensitive Na+ channels contribute to regulatory volume increases in human glioma cells. Am J Physiol Cell Physiol 2007; 293:C1181-5. [PMID: 17615161 DOI: 10.1152/ajpcell.00066.2007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite intensive research, brain tumors remain among the most difficult type of malignancies to treat, due largely to their diffusely invasive nature and the associated difficulty of adequate surgical resection. To migrate through the brain parenchyma and to proliferate, glioma cells must be capable of significant changes in shape and volume. We have previously reported that glioma cells express an amiloride- and psalmotoxin-sensitive cation conductance that is not found in normal human astrocytes. In the present study, we investigated the potential role of this ion channel to mediate regulatory volume increase in glioma cells. We found that the ability of the cells to volume regulate subsequent to cell shrinkage by hyperosmolar solutions was abolished by both amiloride and psalmotoxin 1. This toxin is thought to be a specific peptide inhibitor of acid-sensing ion channel (ASIC1), a member of the Deg/ENaC superfamily of cation channels. We have previously shown this toxin to be an effective blocker of the glioma cation conductance. Our data suggest that one potential role for this conductance may be to restore cell volume during the cell's progression thorough the cell cycle and while the tumor cell migrates within the interstices of the brain.
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Affiliation(s)
- Sandra B Ross
- Dept. Physiology and Biophysics, Univ. of Alabama at Birmingham, 1918 University Blvd., MCLM 704, Birmingham, AL 35294-0005, USA.
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28
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Grifoni SC, Jernigan NL, Hamilton G, Drummond HA. ASIC proteins regulate smooth muscle cell migration. Microvasc Res 2007; 75:202-10. [PMID: 17936312 DOI: 10.1016/j.mvr.2007.08.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 05/08/2007] [Accepted: 08/02/2007] [Indexed: 11/27/2022]
Abstract
The purpose of the present study was to investigate Acid Sensing Ion Channel (ASIC) protein expression and importance in cellular migration. We recently demonstrated that Epithelial Na(+)Channel (ENaC) proteins are required for vascular smooth muscle cell (VSMC) migration; however, the role of the closely related ASIC proteins has not been addressed. We used RT-PCR and immunolabeling to determine expression of ASIC1, ASIC2, ASIC3 and ASIC4 in A10 cells. We used small interference RNA to silence individual ASIC expression and determine the importance of ASIC proteins in wound healing and chemotaxis (PDGF-bb)-initiated migration. We found ASIC1, ASIC2, and ASIC3, but not ASIC4, expression in A10 cells. ASIC1, ASIC2, and ASIC3 siRNA molecules significantly suppressed expression of their respective proteins compared to non-targeting siRNA (RISC) transfected controls by 63%, 44%, and 55%, respectively. Wound healing was inhibited by 10, 20, and 26% compared to RISC controls following suppression of ASIC1, ASIC2, and ASIC3, respectively. Chemotactic migration was inhibited by 30% and 45%, respectively, following suppression of ASIC1 and ASIC3. ASIC2 suppression produced a small, but significant, increase in chemotactic migration (4%). Our data indicate that ASIC expression is required for normal migration and may suggest a novel role for ASIC proteins in cellular migration.
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Affiliation(s)
- Samira C Grifoni
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216, USA
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29
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Meltzer RH, Kapoor N, Qadri YJ, Anderson SJ, Fuller CM, Benos DJ. Heteromeric Assembly of Acid-sensitive Ion Channel and Epithelial Sodium Channel Subunits. J Biol Chem 2007; 282:25548-59. [PMID: 17613525 DOI: 10.1074/jbc.m703825200] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Amiloride-sensitive ion channels are formed from homo- or heteromeric combinations of subunits from the epithelial Na+ channel (ENaC)/degenerin superfamily, which also includes the acid-sensitive ion channel (ASIC) family. These channel subunits share sequence homology and topology. In this study, we have demonstrated, using confocal fluorescence resonance energy transfer microscopy and co-immunoprecipitation, that ASIC and ENaC subunits are capable of forming cross-clade intermolecular interactions. We have also shown that combinations of ASIC1 with ENaC subunits exhibit novel electrophysiological characteristics compared with ASIC1 alone. The results of this study suggest that heteromeric complexes of ASIC and ENaC subunits may underlie the diversity of amiloride-sensitive cation conductances observed in a wide variety of tissues and cell types where co-expression of ASIC and ENaC subunits has been observed.
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Affiliation(s)
- Robert H Meltzer
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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30
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Tang ZQ, Lu YG, Zhou KQ, Xu TL, Chen L. Amiloride attenuates glycine-induced currents in cultured neurons of rat inferior colliculus. Biochem Biophys Res Commun 2006; 350:900-4. [PMID: 17034762 DOI: 10.1016/j.bbrc.2006.09.110] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2006] [Accepted: 09/22/2006] [Indexed: 10/24/2022]
Abstract
Amiloride, a potassium sparing diuretic, is well known to interact with many ion transport systems and modulate the activity of several membrane receptors. However, relatively little information is available as to how amiloride affects membrane receptors of neurons in the brain areas. In the present study, we investigated the effects of amiloride on glycine-induced currents (I(Gly)) in cultured neurons of rat inferior colliculus with whole-cell patch-clamp recordings. Amiloride itself did not activate any current across the neuronal membrane but it reversibly inhibited the amplitude of the I(Gly) in a reversible and concentration-dependent manner, with an IC(50) of 487.4+/-25.3microM (n=5). Amiloride shifted the concentration-response relationship to the right without changing Hill coefficient and without changing the maximum response of the I(Gly). The pre-perfusion of amiloride produced an inhibitory effect on the I(Gly). In addition, amiloride was shown with a voltage ramp protocol to significantly reduce the conductance induced by glycine but not to change the reversal potential of the I(Gly). These results demonstrate that amiloride competitively inhibits the I(Gly) in rat inferior colliculus neurons by decreasing the affinity of glycine to its receptor. Our finding suggests that attention should be paid to the possible side effects of amiloride used as a drug on brain functions in the case of a defective blood-brain barrier and in the case of direct application of this drug into the cerebrospinal fluid for treatment of brain tumors.
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Affiliation(s)
- Zheng-Quan Tang
- Auditory Research Laboratory, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
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31
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Fioretti B, Castigli E, Micheli MR, Bova R, Sciaccaluga M, Harper A, Franciolini F, Catacuzzeno L. Expression and modulation of the intermediate- conductance Ca2+-activated K+ channel in glioblastoma GL-15 cells. Cell Physiol Biochem 2006; 18:47-56. [PMID: 16914889 DOI: 10.1159/000095135] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We report here the expression and properties of the intermediate-conductance Ca(2+)-activated K(+) (IK(Ca)) channel in the GL-15 human glioblastoma cell line. Macroscopic IK(Ca) currents on GL-15 cells displayed a mean amplitude of 7.2+/-0.8 pA/pF at 0 mV, at day 1 after plating. The current was inhibited by clotrimazole (CTL, IC(50)=257 nM), TRAM-34 (IC(50)=55 nM), and charybdotoxin (CTX, IC(50)=10.3 nM). RT-PCR analysis demonstrated the expression of mRNA encoding the IK(Ca) channel in GL-15 cells. Unitary currents recorded using the inside-out configuration had a conductance of 25 pS, a K(D) for Ca(2+) of 188 nM at -100 mV, and no voltage dependence. We tested whether the IKCa channel expression in GL-15 cells could be the result of an increased ERK activity. Inhibition of the ERK pathway with the MEK antagonist PD98059 (25 muM, for 5 days) virtually suppressed the IK(Ca) current in GL-15 cells. PD98059 treatment also increased the length of cellular processes and up-regulated the astrocytic differentiative marker GFAP. A significant reduction of the IKCa current amplitude was also observed with time in culture, with mean currents of 7.17+/-0.75 pA/pF at 1-2 days, and 3.11+/-1.35 pA/pF at 5-6 days after plating. This time-dependent downregulation of the IK(Ca) current was not accompanied by changes in the ERK activity, as assessed by immunoblot analysis. Semiquantitative RT-PCR analysis demonstrated a ~35% reduction of the IK(Ca) channel mRNA resulting from ERK inhibition and a approximately 50% reduction with time in culture.
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Affiliation(s)
- Bernard Fioretti
- Dipartimento di Biologia Cellulare e Ambientale, Universita' di Perugia, CEMIN, Centro di Eccellenza "Materiali Innovativi Nanostrutturati", Universita' di Perugia, Italy.
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Wu WKK, Li GR, Wong HPS, Hui MKC, Tai EKK, Lam EKY, Shin VY, Ye YN, Li P, Yang YH, Luo JC, Cho CH. Involvement of Kv1.1 and Nav1.5 in proliferation of gastric epithelial cells. J Cell Physiol 2006; 207:437-44. [PMID: 16331678 DOI: 10.1002/jcp.20576] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In the present study, patch clamp experiments demonstrated the expression of multiple ionic currents, including a Ba2+-sensitive inward rectifier K+ current (IKir), a 4-aminopyridine- (4-AP) sensitive delayed rectifier K+ current (IKDR), and a nifedipine-sensitive, tetrodotoxin-resistant inward Na+ current (INa.TTXR) in the non-transformed rat gastric epithelial cell line RGM-1. RT-PCR revealed molecular identities of mRNAs for the functional ionic currents, including Kir1.2 for IKir, Kv1.1, Kv1.6, and Kv2.1 for IKDR, and Nav1.5 for INa.TTXR. Pharmacologic blockade of Kv and Nav, but not Kir, suppressed RGM-1 cell proliferation. To further elucidate which subtypes of the ion channels were involved in cell proliferation, RNA interference was employed to knockdown specific gene expression. Downregulation of Kv1.1 or Nav1.5 by RNA interference suppressed RGM-1 cell proliferation. To conclude, our study is the first to delineate the expression of ion channels and their functions as growth modulators in gastric epithelial cells.
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Affiliation(s)
- William Ka Kei Wu
- Department of Pharmacology, Faculty of Medicine, The University of Hong Kong, Hong Kong, China
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Vila-Carriles WH, Kovacs GG, Jovov B, Zhou ZH, Pahwa AK, Colby G, Esimai O, Gillespie GY, Mapstone TB, Markert JM, Fuller CM, Bubien JK, Benos DJ. Surface expression of ASIC2 inhibits the amiloride-sensitive current and migration of glioma cells. J Biol Chem 2006; 281:19220-32. [PMID: 16704974 DOI: 10.1074/jbc.m603100200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gliomas are primary brain tumors with a complex biology characterized by antigenic and genomic heterogeneity and a propensity for invasion into normal brain tissue. High grade glioma cells possess a voltage-independent, amiloride-inhibitable, inward Na+ current. This current does not exist in normal astrocytes or low grade tumor cells. Inhibition of this conductance decreases glioma growth and cell migration making it a potential therapeutic target. Our previous results have shown that the acid-sensing ion channels (ASICs), members of the epithelial Na+ channel (ENaC)/degenerin (DEG) family of ion channels are part of this current pathway. We hypothesized that one member of the ENaC/DEG family, ASIC2, is retained intracellularly and that it is the lack of functional expression of ASIC2 at the cell surface that results in hyperactivity of this conductance in high grade gliomas. In this study we show that the chemical chaperone, glycerol, and the transcriptional regulator, sodium 4-phenylbutyrate, inhibit the constitutively activated inward current and reduce cell growth and migration in glioblastoma multiforme. The results suggest that these compounds induce the movement of ASIC2 to the plasma membrane, and once there, the basally active inward current characteristic of glioma cells is abolished by inherent negative regulatory mechanisms. This in turn compromises the ability of the glioma cell to migrate and proliferate. These results support the hypothesis that the conductance pathway in high grade glioma cells is comprised of ENaC/DEG subunits and that abolishing this channel activity promotes a reversion of a high grade glioma cell to a phenotype resembling that of normal astrocytes.
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Affiliation(s)
- Wanda H Vila-Carriles
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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Lingueglia E, Deval E, Lazdunski M. FMRFamide-gated sodium channel and ASIC channels: a new class of ionotropic receptors for FMRFamide and related peptides. Peptides 2006; 27:1138-52. [PMID: 16516345 DOI: 10.1016/j.peptides.2005.06.037] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Accepted: 06/22/2005] [Indexed: 12/13/2022]
Abstract
FMRFamide and related peptides typically exert their action through G-protein coupled receptors. However, two ionotropic receptors for these peptides have recently been identified. They are both members of the epithelial amiloride-sensitive Na+ channel and degenerin (ENaC/DEG) family of ion channels. The invertebrate FMRFamide-gated Na+ channel (FaNaC) is a neuronal Na+-selective channel which is directly gated by micromolar concentrations of FMRFamide and related tetrapeptides. Its response is fast and partially desensitizing, and FaNaC has been proposed to participate in peptidergic neurotransmission. On the other hand, mammalian acid-sensing ion channels (ASICs) are not gated but are directly modulated by FMRFamide and related mammalian peptides like NPFF and NPSF. ASICs are activated by external protons and are therefore extracellular pH sensors. They are expressed both in the central and peripheral nervous system and appear to be involved in many physiological and pathophysiological processes such as hippocampal long-term potentiation and defects in learning and memory, acquired fear-related behavior, retinal function, brain ischemia, pain sensation in ischemia and inflammation, taste perception, hearing functions, and mechanoperception. The potentiation of ASIC activity by endogenous RFamide neuropeptides probably participates in the response to noxious acidosis in sensory and central neurons. Available data also raises the possibility of the existence of still unknown FMRFamide related endogenous peptides acting as direct agonists for ASICs.
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Affiliation(s)
- Eric Lingueglia
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS-Université de Nice-Sophia Antipolis UMR 6097, 660 route des Lucioles, Sophia Antipolis, 06560 Valbonne, France.
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35
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Masi A, Becchetti A, Restano-Cassulini R, Polvani S, Hofmann G, Buccoliero AM, Paglierani M, Pollo B, Taddei GL, Gallina P, Di Lorenzo N, Franceschetti S, Wanke E, Arcangeli A. hERG1 channels are overexpressed in glioblastoma multiforme and modulate VEGF secretion in glioblastoma cell lines. Br J Cancer 2005; 93:781-92. [PMID: 16175187 PMCID: PMC2361632 DOI: 10.1038/sj.bjc.6602775] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Recent studies have led to considerable advancement in our understanding of the molecular mechanisms that underlie the relentless cell growth and invasiveness of human gliomas. Partial understanding of these mechanisms has (1) improved the classification for gliomas, by identifying prognostic subgroups, and (2) pointed to novel potential therapeutic targets. Some classes of ion channels have turned out to be involved in the pathogenesis and malignancy of gliomas. We studied the expression and properties of K+ channels in primary cultures obtained from surgical specimens: human ether a gò-gò related (hERG)1 voltage-dependent K+ channels, which have been found to be overexpressed in various human cancers, and human ether a gò-gò-like 2 channels, that share many of hERG1's biophysical features. The expression pattern of these two channels was compared to that of the classical inward rectifying K+ channels, IRK, that are widely expressed in astrocytic cells and classically considered a marker of astrocytic differentiation. In our study, hERG1 was found to be specifically overexpressed in high-grade astrocytomas, that is, glioblastoma multiforme (GBM). In addition, we present evidence that, in GBM cell lines, hERG1 channel activity actively contributes to malignancy by promoting vascular endothelial growth factor secretion, thus stimulating the neoangiogenesis typical of high-grade gliomas. Our data provide important confirmation for studies proposing the hERG1 channel as a molecular marker of tumour progression and a possible target for novel anticancer therapies.
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Affiliation(s)
- A Masi
- Department of Experimental Pathology and Oncology, University of Firenze, Viale GB Morgagni, 50, 50134 Firenze, Italy
| | - A Becchetti
- Department of Biotechnology and Biosciences, University of Milano Bicocca, Piazza della Scienza, 2, 20126 Milano, Italy
| | - R Restano-Cassulini
- Department of Biotechnology and Biosciences, University of Milano Bicocca, Piazza della Scienza, 2, 20126 Milano, Italy
| | - S Polvani
- Department of Experimental Pathology and Oncology, University of Firenze, Viale GB Morgagni, 50, 50134 Firenze, Italy
| | - G Hofmann
- Department of Experimental Pathology and Oncology, University of Firenze, Viale GB Morgagni, 50, 50134 Firenze, Italy
| | - A M Buccoliero
- Department of Human Pathology and Oncology, University of Firenze, Viale GB Morgagni, 88, 50134 Firenze, Italy
| | - M Paglierani
- Department of Human Pathology and Oncology, University of Firenze, Viale GB Morgagni, 88, 50134 Firenze, Italy
| | - B Pollo
- Istituto Neurologico Besta, Via Celoria, 11, 20133 Milano, Italy
| | - G L Taddei
- Department of Human Pathology and Oncology, University of Firenze, Viale GB Morgagni, 88, 50134 Firenze, Italy
| | - P Gallina
- Department of Neurosurgery, University of Firenze, Largo P Palagi 1, 50139, Firenze, Italy
| | - N Di Lorenzo
- Department of Neurosurgery, University of Firenze, Largo P Palagi 1, 50139, Firenze, Italy
| | - S Franceschetti
- Istituto Neurologico Besta, Via Celoria, 11, 20133 Milano, Italy
| | - E Wanke
- Department of Biotechnology and Biosciences, University of Milano Bicocca, Piazza della Scienza, 2, 20126 Milano, Italy
| | - A Arcangeli
- Department of Experimental Pathology and Oncology, University of Firenze, Viale GB Morgagni, 50, 50134 Firenze, Italy
- Department of Experimental Pathology and Oncology, University of Firenze, Viale GB Morgagni, 50, 50134 Firenze, Italy. E-mail:
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Abstract
Membrane ion channels are essential for cell proliferation and appear to have a role in the development of cancer. This has initially been demonstrated for potassium channels and is meanwhile also suggested for other cation channels and Cl- channels. For some of these channels, like voltage-gated ether à go-go and Ca2+-dependent potassium channels as well as calcium and chloride channels, a cell cycle-dependent function has been demonstrated. Along with other membrane conductances, these channels control the membrane voltage and Ca2+ signaling in proliferating cells. Homeostatic parameters, such as the intracellular ion concentration, cytosolic pH and cell volume, are also governed by the activity of ion channels. Thus it will be an essential task for future studies to unravel cell cycle-specific effects of ion channels and non-specific homeostatic functions. When studying the role of ion channels in cancer cells, it is indispensable to choose experimental conditions that come close to the in vivo situation. Thus, environmental parameters, such as low oxygen pressure, acidosis and exposure to serum proteins, have to be taken into account. In order to achieve clinical application, more studies on the original cancer tissue are required, and improved animal models. Finally, it will be essential to generate more potent and specific inhibitors of ion channels to overcome the shortcomings of some of the current approaches.
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Affiliation(s)
- Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstrasse 31, Regensburg, D-93053, Germany.
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Li Y, Li YF, Xu TL. Amiloride inhibition of glycinergic miniature IPSCs in mechanically dissociated rat spinal neurons. Neurosci Lett 2003; 349:17-20. [PMID: 12946576 DOI: 10.1016/s0304-3940(03)00672-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The effect of amiloride on glycinergic transmission in mechanically dissociated rat spinal dorsal horn neurons was examined with the use of whole-cell patch-clamp recording. Amiloride reversibly reduced both the frequency and amplitude of spontaneous glycinergic miniature IPSCs (mIPSCs) and its inhibitory effect on glycinergic mIPSCs persisted in either Ca2+-free or Na+-free external solutions while it disappeared in K+-free external solution. Analysis of the relationship between mIPSCs amplitude and frequency at various holding potentials shows that amiloride inhibition of glycinergic mIPSC frequency could result indirectly from its inhibition of amplitude.
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Affiliation(s)
- Yong Li
- Department of Neurobiology and Biophysics, University of Science and Technology of China, Hefei 230027, China
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Xia J, Zhou ZH, Bubien JK, Fuller CM, Markert JM, Mapstone TB, Gillespie GY, Benos DJ. Molecular cloning and characterization of human acid sensing ion channel (ASIC)2 gene promoter. Gene 2003; 313:91-101. [PMID: 12957380 DOI: 10.1016/s0378-1119(03)00633-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Acid sensing ion channel (ASIC)2 belongs to the amiloride-sensitive Na(+)-channel/ degenerin family. Our previous studies suggested that differential regulation of ASIC2 expression occurs between high-grade glial-derived tumor cells and normal astrocytes. To investigate the mechanisms involved in the regulation of ASIC2 gene expression, the human ASIC2 promoter region (-1551 to +117) was cloned and characterized. The ASIC2 promoter lacked a canonical TATA box, but contained one putative CCAAT box. Nucleotide sequencing of the promoter revealed the presence of a number of transcription factor-binding sites and a 404 bp CpG island upstream the transcription start site. Nested deletion mutants and transfection results showed that the construct between -133 and +117 base pairs conferred basal transcription specific activity. Mutation of Sp1 and CP2 sites in this region resulted in a 70 and 95% decrease in promoter activity, respectively. Gel shift assays demonstrated the existence of specific protein binding to the SP1 and CP2 elements. There was no mutation in the CpG island in six glioma cell lines, but methylation-specific PCR showed methylation in some of glioma cell lines and tumor tissues, and treatment with the methylation inhibitor 5-Aza-2'-deoxycytidine could partially restore ASIC2 expression in cell lines, suggesting that epigenetic mechanisms may contribute to dysregulated ASIC2 expression.
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Affiliation(s)
- Jiazeng Xia
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, AL 35294-0005, USA
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39
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Abstract
The modulatory effect of amiloride on glycine-activated current (I(Gly)) was investigated in acutely dissociated rat spinal dorsal horn neurons using the whole-cell patch clamp technique. Amiloride inhibited I(Gly) reversibly in a concentration-dependent manner. It shifted the concentration-response relationship to the right without altering the maximum response and Hill coefficient of the I(Gly). Amiloride did not change the ion selectivity of glycine receptor either. In addition, Na(+) - or Ca(2+) -free extracellular solutions and intracellular application of amiloride did not alter the amiloride inhibition of I(Gly). These results indicate that amiloride directly inhibited the glycine receptor response by decreasing the affinity of glycine to its receptor.
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Affiliation(s)
- Yan-Fang Li
- Department of Neurobiology and Biophysics, University of Science and Technology of China, Hefei 230027, China
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40
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Berdiev BK, Xia J, McLean LA, Markert JM, Gillespie GY, Mapstone TB, Naren AP, Jovov B, Bubien JK, Ji HL, Fuller CM, Kirk KL, Benos DJ. Acid-sensing ion channels in malignant gliomas. J Biol Chem 2003; 278:15023-34. [PMID: 12584187 DOI: 10.1074/jbc.m300991200] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
High grade glioma cells derived from patient biopsies express an amiloride-sensitive sodium conductance that has properties attributed to the human brain sodium channel family, also known as acid-sensing ion channels (ASICs). This amiloride-sensitive conductance was not detected in cells obtained from normal brain tissue or low grade or benign tumors. Differential gene profiling data showed that ASIC1 and ASIC2 mRNA were present in normal and low grade tumor cells. Although ASIC1 was present in all of the high grade glial cells examined, ASIC2 mRNA was detected in less than half. The main purpose of our work was to examine the molecular mechanisms that may underlie the constitutively activated sodium currents present in high grade glioma cells. Our results show that 1) gain-of-function mutations of ASIC1 were not present in a number of freshly resected and cultured high grade gliomas, 2) syntaxin 1A inhibited ASIC currents only when ASIC1 and ASIC2 were co-expressed, and 3) the inhibition of ASIC currents by syntaxin 1A had an absolute requirement for either gamma- or delta-hENaC. Transfection of cultured cells originally derived from high grade gliomas (U87-MG and SK-MG1) with ASIC2 abolished basal amiloride-sensitive sodium conductance; this inhibition was reversed by dialysis of the cell interior with Munc-18, a syntaxin-binding protein that typically blocks the interaction of syntaxin with other proteins. Thus, syntaxin 1A cannot inhibit Na(+) permeability in the absence of adequate plasma membrane ASIC2 expression, accounting for the observed functional expression of amiloride-sensitive currents in high grade glioma cells.
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Affiliation(s)
- Bakhrom K Berdiev
- Department of Physiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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41
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Berdiev BK, Xia J, Jovov B, Markert JM, Mapstone TB, Gillespie GY, Fuller CM, Bubien JK, Benos DJ. Protein kinase C isoform antagonism controls BNaC2 (ASIC1) function. J Biol Chem 2002; 277:45734-40. [PMID: 12244121 DOI: 10.1074/jbc.m208995200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
We explored the involvement of protein kinase C (PKC) and its isoforms in the regulation of BNaC2. Reverse transcriptase PCR evaluation of PKC isoform expression at the level of mRNA revealed the presence of alpha and epsilon/epsilon' in all glioma cell lines analyzed; most, but not all cell lines expressed delta and zeta. No messages were found for the betaI and betaII isotypes of PKC in the tumor cells. Normal astrocytes expressed beta but not gamma. The essential features of these results were confirmed at the protein level by Western analysis. This disproportionate pattern of PKC isoform expression in glioma cell lines was further echoed in the functional effects of these PKC isoforms on BNaC2 activity in bilayers. PKC holoenzyme or the combination of PKCbetaI and PKCbetaII isoforms inhibited BNaC2. Neither PKCepsilon nor PKCzeta or their combination had any effect on BNaC2 activity in bilayers. The inhibitory effect of the PKCbetaI and PKCbetaII mixture on BNaC2 activity was abolished by a 5-fold excess of a PKCepsilon and PKCzeta combination. PKC holoenzymes, PKCbetaI, PKCbetaII, PKCdelta, PKCepsilon, and PKCzeta phosphorylated BNaC2 in vitro. In patch clamp experiments, the combination of PKCbetaI and PKCbetaII inhibited the basally activated inward Na(+) conductance. The variable expression of the PKC isotypes and their functional antagonism in regulating BNaC2 activity support the idea that the participation of multiple PKC isotypes contributes to the overall activity of BNaC2.
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Affiliation(s)
- Bakhrom K Berdiev
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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42
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Fisher JL. Amiloride inhibition of gamma-aminobutyric acid(A) receptors depends upon the alpha subunit subtype. Mol Pharmacol 2002; 61:1322-8. [PMID: 12021393 DOI: 10.1124/mol.61.6.1322] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
gamma-Aminobutyric acid(A) (GABA(A)) receptors (GABARs) are responsible for most fast inhibitory neurotransmission in the mammalian brain. The GABARs contain several allosteric modulatory sites, many of which are useful clinically. The activity of most of these modulators depends upon the subunit composition of the receptor. The diuretic amiloride was previously reported to inhibit GABARs in frog sensory neurons. We measured its effects on recombinant GABARs to determine its mechanism of action at mammalian receptors and to examine the effect of subunit composition. Amiloride acted primarily as a competitive antagonist, reducing the sensitivity of the receptor to GABA without affecting the maximal current amplitude. Receptors containing an alpha6 subunit were about 10-fold more sensitive to amiloride than those containing other alpha subunits. In contrast, the identity of the beta or gamma subtype had little effect on amiloride sensitivity. Although several other modulators have specific effects at alpha6-containing receptors, amiloride is the first inhibitor to be reported with no additional dependence on the identity of the beta or gamma subunit. Therefore, it probably represents a unique modulatory site on the GABAR, which could be useful for developing drugs targeting these receptors. The selective activity of amiloride could also be helpful for isolating the contribution of receptors composed of alpha6 subtypes in heterogeneous native GABAR populations.
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Affiliation(s)
- Janet L Fisher
- Department of Pharmacology and Physiology, University of South Carolina School of Medicine, Columbia, South Carolina 29208, USA.
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Berdiev BK, Mapstone TB, Markert JM, Gillespie GY, Lockhart J, Fuller CM, Benos DJ. pH alterations "reset" Ca2+ sensitivity of brain Na+ channel 2, a degenerin/epithelial Na+ ion channel, in planar lipid bilayers. J Biol Chem 2001; 276:38755-61. [PMID: 11514582 DOI: 10.1074/jbc.m107266200] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the degenerin/epithelial Na(+) channel superfamily of ion channels subserve many functions, ranging from whole body sodium handling to mechanoelectrical transduction. We studied brain Na(+) channel 2 (BNaC-2) in planar lipid bilayers to examine its single channel properties and regulation by Ca(2+). Upon incorporation of vesicles made from membranes of oocytes expressing either wild-type (WT) BNaC-2 or BNaC-2 with a gain-of-function (GF) point mutation (G433F), functional channels with different properties were obtained. WT BNaC-2 resided in a closed state with short openings, whereas GF BNaC-2 was constitutively activated; a decrease in the pH in the trans compartment of the bilayer activated WT BNaC-2 and decreased its permeability for Na(+) over K(+). Moreover, these maneuvers made the WT channel more resistant to amiloride. In contrast, GF BNaC-2 did not respond to a decrease in pH, and its amiloride sensitivity and selectivity for Na(+) over K(+) were unaffected by this pH change. Buffering the bathing solutions with EGTA to reduce the free [Ca(2+)] to <10 nm increased WT single channel open probability 10-fold, but not that of GF BNaC-2. Ca(2+) blocked both WT and GF BNaC-2 in a dose- and voltage-dependent fashion; single channel conductances were unchanged. A drop in pH reduced the ability of Ca(2+) to inhibit these channels. These results show that BNaC-2 is an amiloride-sensitive sodium channel and suggest that pH activation of these channels could be, in part, a consequence of H(+) "interference" with channel regulation by Ca(2+).
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Affiliation(s)
- B K Berdiev
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294-0005, USA
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Gomez-Sanchez CE, Gomez-Sanchez EP. Role of central mineralocorticoid receptors in cardiovascular disease. Curr Hypertens Rep 2001; 3:263-9. [PMID: 11353578 DOI: 10.1007/s11906-001-0049-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Mineralocorticoids act directly through their receptors in specific centers in the central nervous system, kidneys, heart, and vascular smooth muscle to mediate hemodynamic homeostasis. These steroids also modulate renal and cardiovascular function indirectly through the autonomic nervous system. Complex homeostatic mechanisms under normal hormonal control become pathogenic when there is an excess of regulatory hormone. Experiments in which mineralocorticoid receptor antagonists or antisense oligodeoxynucleotides were administered centrally have clearly shown that centrally mediated effects on salt appetite, baroreceptor function, and autonomic drive to the renal and cardiovascular systems are crucial to the pathogenesis of hypertension and cardiovascular disease of hyperaldosteronism, and certain forms of genetic hypertension.
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Affiliation(s)
- C E Gomez-Sanchez
- Division of Endocrinology, The University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.
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45
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Bubien JK, Watson B, Khan MA, Langloh AL, Fuller CM, Berdiev B, Tousson A, Benos DJ. Expression and regulation of normal and polymorphic epithelial sodium channel by human lymphocytes. J Biol Chem 2001; 276:8557-66. [PMID: 11113130 DOI: 10.1074/jbc.m008886200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gene expression, protein expression, and function of amiloride-sensitive sodium channels were examined in human lymphocytes from normal individuals and individuals with Liddle's disease. Using reverse transcriptase polymerase chain reactions, expression of all three cloned epithelial sodium channel (ENaC) subunits was detected in lymphocytes. Polyclonal antibodies to bovine alpha-ENaC bound to the plasma membrane of normal and Liddle's lymphocytes. A quantitative analysis of fluorescence-tagged ENaC antibodies indicated a 2.5-fold greater surface binding of the antibodies to Liddle's lymphocytes compared with normal lymphocytes. The relative binding intensity increased significantly (25%; p < 0.001) for both normal and Liddle's cells after treatment with 40 microM 8-CPT-cAMP. Amiloride-sensitive whole cell currents were recorded under basal and cAMP-treated conditions for both cell types. Liddle's cells had a 4.5-fold larger inward sodium conductance compared with normal cells. A specific 25% increase in the inward sodium current was observed in normal cells in response to cAMP treatment. Outside-out patches from both cell types under both treatment conditions revealed no obvious differences in the single channel conductance. The P(open) was 4.2 +/- 3.9% for patches from non-Liddle's cells, and 27.7 +/- 5.4% in patches from Liddle's lymphocytes. Biochemical purification of a protein complex, using the same antibodies used for the immunohistochemistry, yielded a functional sodium channel complex that was inhibited by amiloride when reconstituted into lipid vesicles and incorporated into planar lipid bilayers. These four independent methodologies yielded findings consistent with the hypotheses that human lymphocytes express functional, regulatable ENaC and that the mutation responsible for Liddle's disease induces excessive channel expression.
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Affiliation(s)
- J K Bubien
- Departments of Physiology and Biophysics, Cell Biology, and Gerentology and Geriatric Medicine, University of Alabama, Birmingham, Alabama 35294, USA.
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Markert JM, Fuller CM, Gillespie GY, Bubien JK, McLean LA, Hong RL, Lee K, Gullans SR, Mapstone TB, Benos DJ. Differential gene expression profiling in human brain tumors. Physiol Genomics 2001; 5:21-33. [PMID: 11161003 DOI: 10.1152/physiolgenomics.2001.5.1.21] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Gene expression profiling of three human temporal lobe brain tissue samples (normal) and four primary glioblastoma multiforme (GBM) tumors using oligonucleotide microarrays was done. Moreover, confirmation of altered expression was performed by whole cell patch clamp, immunohistochemical staining, and RT-PCR. Our results identified several ion and solute transport-related genes, such as N-methyl-d-aspartate (NMDA) receptors, alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)-2 receptors, GABA(A) receptor subunits alpha3, beta1, beta2, and beta3, the glutamate transporter, the glutamate/aspartate transporter II, the potassium channel K(V)2.1, hK(V)beta3, and the sodium/proton exchanger 1 (NHE-1), that are all downregulated in the tumors compared with the normal tissues. In contrast, aquaporin-1, possibly aquaporins-3 and -5, and GLUT-3 message appeared upregulated in the tumors. Our results also confirmed previous work showing that osteopontin, nicotinamide N-methyltransferase, murine double minute 2 (MDM2), and epithelin (granulin) are upregulated in GBMs. We also demonstrate for the first time that the cytokine and p53 binding protein, macrophage migration inhibitory factor (MIF), appears upregulated in GBMs. These results indicate that the modulation of ion and solute transport genes and heretofore unsuspected cytokines (i.e., MIF) may have profound implications for brain tumor cell biology and thus may identify potential useful therapeutic targets in GBMs.
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Affiliation(s)
- J M Markert
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama 35294-0005, USA
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Benos DJ, Stanton BA. Functional domains within the degenerin/epithelial sodium channel (Deg/ENaC) superfamily of ion channels. J Physiol 1999; 520 Pt 3:631-44. [PMID: 10545131 PMCID: PMC2269617 DOI: 10.1111/j.1469-7793.1999.00631.x] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Application of recombinant DNA technology and electrophysiology to the study of amiloride-sensitive Na+ channels has resulted in an enormous increase in the understanding of the structure-function relationships of these channels. Moreover, this knowledge has permitted the elucidation of the physiological roles of these ion channels in cellular processes as diverse as transepithelial salt and water movement, taste perception, volume regulation, nociception, neuronal function, mechanosensation, and even defaecation. Although members of this ever-growing superfamily of ion channels (the Deg/ENaC superfamily) share little amino acid identity, they are all organized similarly, namely, two short N- and C-termini, two short membrane-spanning segments, and a very large extracellular loop domain. In this brief Topical Review, we discuss the structural features of each domain of this Deg/ENaC superfamily and, using ENaC as a model, show how each domain relates to overall channel function.
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Affiliation(s)
- D J Benos
- Department of Physiology and Biophysics, University of Alabama at Birmingham, 1918 University Boulevard, Birmingham, AL 35294-0005, USA.
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