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Koch A, Hofschröer V, Schwab A. Na + /H + exchanger NHE1 is active at cell-cell contacts and facilitates cell dissemination during collective migration of melanoma cells. Exp Dermatol 2024; 33:e14983. [PMID: 38009253 DOI: 10.1111/exd.14983] [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: 07/03/2023] [Revised: 11/07/2023] [Accepted: 11/13/2023] [Indexed: 11/28/2023]
Abstract
Tumour cell detachment from the primary tumour is an early and crucial step of the metastatic cascade. At the single cell level, it was already shown that migrating melanoma cells establish both intra- and extracellular pH gradients and that the Na+ /H+ exchanger NHE1 accumulates at the leading edges to strengthen cell-matrix interactions. However, less is known about the role of NHE1 in collective cell migration and the specific pH microenvironment at tumour cell-cell contacts. We used MV3 melanoma cells transfected with a NHE1-expressing vector or a control vector. NHE1 localization at cell-cell contacts was assessed via immunofluorescence imaging. Collective migration was analysed by live-cell imaging. The NHE1 activity and the perimembranous pH were measured both intra- and extracellularly by ratiometric fluorescence microscopy. NHE1 clearly localizes at cell-cell contacts. Its overexpression further increases migratory speed and translocation in multidirectional pathway analyses. NHE1 overexpressing MV3 cells also move further away from their neighbouring cells during wound closure assays. pH measurements revealed that the NHE1 is highly active at cell-cell contacts of melanoma cells. NHE1-mediated pH dynamics at such contact sites are more prominent in NHE1-overexpressing melanoma cells. Our findings highlight the contribution of the NHE1 towards modulation and plasticity of melanoma cell-cell contacts. We propose that its localization and functional activity at cell-cell contacts promotes evasion of single melanoma cells from the primary tumour.
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Affiliation(s)
- Alexander Koch
- Institute of Physiology II, University of Münster, Münster, Germany
| | | | - Albrecht Schwab
- Institute of Physiology II, University of Münster, Münster, Germany
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2
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Fujita T, Seist R, Kao SY, Soares V, Panano L, Khetani RS, Landegger LD, Batts S, Stankovic KM. miR-431 secreted by human vestibular schwannomas increases the mammalian inner ear's vulnerability to noise trauma. Front Neurol 2023; 14:1268359. [PMID: 37885485 PMCID: PMC10598552 DOI: 10.3389/fneur.2023.1268359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/20/2023] [Indexed: 10/28/2023] Open
Abstract
Introduction Vestibular schwannoma (VS) is an intracranial tumor that arises on the vestibular branch of cranial nerve VIII and typically presents with sensorineural hearing loss (SNHL). The mechanisms of this SNHL are postulated to involve alterations in the inner ear's microenvironment mediated by the genetic cargo of VS-secreted extracellular vesicles (EVs). We aimed to identify the EV cargo associated with poor hearing and determine whether its delivery caused hearing loss and cochlear damage in a mouse model in vivo. Methods VS tissue was collected from routinely resected tumors of patients with good (VS-GH) or poor (VS-PH) pre-surgical hearing measured via pure-tone average and word recognition scores. Next-generation sequencing was performed on RNA isolated from cultured primary human VS cells and EVs from VS-conditioned media, stratified by patients' hearing ability. microRNA expression levels were compared between VS-PH and VS-GH samples to identify differentially expressed candidates for packaging into a synthetic adeno-associated viral vector (Anc80L65). Viral vectors containing candidate microRNA were infused to the semicircular canals of mice to evaluate the effects on hearing, including after noise exposure. Results Differentially expressed microRNAs included hsa-miR-431-5p (enriched in VS-PH) and hsa-miR-192-5p (enriched in VS-GH). Newborn mice receiving intracochlear injection of viral vectors over-expressing hsa-miR-431-GFP, hsa-miR-192-GFP, or GFP only (control) had similar hearing 6 weeks post-injection. However, after acoustic trauma, the miR-431 group displayed significantly worse hearing, and greater loss of synaptic ribbons per inner hair cell in the acoustically traumatized cochlear region than the control group. Conclusion Our results suggest that miR-431 contributes to VS-associated hearing loss following cochlear stress. Further investigation is needed to determine whether miR-431 is a potential therapeutic target for SNHL.
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Affiliation(s)
- Takeshi Fujita
- Department of Otolaryngology – Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, United States
| | - Richard Seist
- Department of Otolaryngology – Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, United States
| | - Shyan-Yuan Kao
- Department of Otolaryngology – Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, United States
| | - Vitor Soares
- Department of Otolaryngology – Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, United States
| | - Lorena Panano
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, United States
| | - Radhika S. Khetani
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, United States
| | - Lukas D. Landegger
- Department of Otolaryngology – Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, United States
| | - Shelley Batts
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Konstantina M. Stankovic
- Department of Otolaryngology – Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, United States
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
- Wu Tsai Neuroscience Institute, Stanford University, Stanford, CA, United States
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3
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Pethő Z, Najder K, Beel S, Fels B, Neumann I, Schimmelpfennig S, Sargin S, Wolters M, Grantins K, Wardelmann E, Mitkovski M, Oeckinghaus A, Schwab A. Acid-base homeostasis orchestrated by NHE1 defines the pancreatic stellate cell phenotype in pancreatic cancer. JCI Insight 2023; 8:e170928. [PMID: 37643024 PMCID: PMC10619433 DOI: 10.1172/jci.insight.170928] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 08/24/2023] [Indexed: 08/31/2023] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) progresses in an organ with a unique pH landscape, where the stroma acidifies after each meal. We hypothesized that disrupting this pH landscape during PDAC progression triggers pancreatic stellate cells (PSCs) and cancer-associated fibroblasts (CAFs) to induce PDAC fibrosis. We revealed that alkaline environmental pH was sufficient to induce PSC differentiation to a myofibroblastic phenotype. We then mechanistically dissected this finding, focusing on the involvement of the Na+/H+ exchanger NHE1. Perturbing cellular pH homeostasis by inhibiting NHE1 with cariporide partially altered the myofibroblastic PSC phenotype. To show the relevance of this finding in vivo, we targeted NHE1 in murine PDAC (KPfC). Indeed, tumor fibrosis decreased when mice received the NHE1-inhibitor cariporide in addition to gemcitabine treatment. Moreover, the tumor immune infiltrate shifted from granulocyte rich to more lymphocytic. Taken together, our study provides mechanistic evidence on how the pancreatic pH landscape shapes pancreatic cancer through tuning PSC differentiation.
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Affiliation(s)
| | | | - Stephanie Beel
- Institute of Molecular Tumor Biology, University of Münster, Münster, Germany
| | - Benedikt Fels
- Institute of Physiology II and
- Institute of Physiology, University of Lübeck, Lübeck, Germany
| | | | | | | | - Maria Wolters
- Gerhard-Domagk-Institute of Pathology, University of Münster, Münster, Germany
| | - Klavs Grantins
- Gerhard-Domagk-Institute of Pathology, University of Münster, Münster, Germany
| | - Eva Wardelmann
- Gerhard-Domagk-Institute of Pathology, University of Münster, Münster, Germany
| | - Miso Mitkovski
- City Campus Light Microscopy Facility, Max Planck Institute for Multidisciplinary Sciences, Goettingen, Germany
| | - Andrea Oeckinghaus
- Institute of Molecular Tumor Biology, University of Münster, Münster, Germany
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Buenaventura RGM, Merlino G, Yu Y. Ez-Metastasizing: The Crucial Roles of Ezrin in Metastasis. Cells 2023; 12:1620. [PMID: 37371090 DOI: 10.3390/cells12121620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/08/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
Ezrin is the cytoskeletal organizer and functions in the modulation of membrane-cytoskeleton interaction, maintenance of cell shape and structure, and regulation of cell-cell adhesion and movement, as well as cell survival. Ezrin plays a critical role in regulating tumor metastasis through interaction with other binding proteins. Notably, Ezrin has been reported to interact with immune cells, allowing tumor cells to escape immune attack in metastasis. Here, we review the main functions of Ezrin, the mechanisms through which it acts, its role in tumor metastasis, and its potential as a therapeutic target.
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Affiliation(s)
- Rand Gabriel M Buenaventura
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Glenn Merlino
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yanlin Yu
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Yang J, Huang T, Zhang J, Bai G, Wang W, Yao J, Chen Z, Tu C. Sulphur dioxide and fluoride co-exposure cause enamel damage by disrupting the Cl -/HCO 3- ion transport. J Trace Elem Med Biol 2023; 77:127131. [PMID: 36630759 DOI: 10.1016/j.jtemb.2023.127131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 11/21/2022] [Accepted: 01/04/2023] [Indexed: 01/07/2023]
Abstract
OBJECTIVE Although there is growing evidence linking the exposure to sulphur dioxide (SO2) and fluoride to human diseases, there is little data on the co-exposure of SO2 and fluoride. Moreover, literature on SO2 and fluoride co-exposure to enamel damage is insufficient. In this work, we concentrate on the concurrent environmental issues of excessive SO2 and fluoride in several coal-consuming regions. METHOD To identify the toxicity of SO2 and fluoride exposure either separately or together, we used both ICR mice and LS8 cells, and factorial design was employed to assess the type of potential combined action. RESULT In this study, co-exposure to SO2 and fluoride exacerbated enamel damage, resulting in more severe enamel defects of incisor and the damage occurred earlier. Cl-/HCO3- exchanger expression is increased by SO2 and fluoride in mouse incisor. Consistent with in vivo results, co-exposure of SO2 and fluoride decreased pHi and increased [Cl-]i level by increasing the expression of the Cl-/HCO3- exchanger in LS8 cells. Furthermore, SO2 and F may increase merlin protein expression, and merlin deficiency causes AE2 expression to decrease in vitro. CONCLUSION Overall, these results indicate that co-exposure to SO2 and fluoride may result in more toxicity both in vitro and in vivo than a single exposure to SO2 and fluoride, suggesting that residents in areas contaminated with SO2 and fluoride may be more likely to suffer enamel damage.
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Affiliation(s)
- Junlin Yang
- School of Public Health, Guizhou Medical University, Guian New Region, China; The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Tongtong Huang
- School of Public Health, Guizhou Medical University, Guian New Region, China
| | - Jianghui Zhang
- School of Public Health, Guizhou Medical University, Guian New Region, China
| | - Guohui Bai
- Key Laboratory of Oral Disease Research, School of Stomatology, Zunyi Medical University, Zunyi, China
| | - Wentai Wang
- School of Public Health, Guizhou Medical University, Guian New Region, China
| | - Jie Yao
- School of Public Health, Guizhou Medical University, Guian New Region, China
| | - Zheng Chen
- School of Public Health, Guizhou Medical University, Guian New Region, China
| | - Chenglong Tu
- Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guian New Region, China; Toxicity Testing Center of Guizhou Medical University, Guiyang, China.
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Malinda RR, Zeeberg K, Sharku PC, Ludwig MQ, Pedersen LB, Christensen ST, Pedersen SF. TGFβ Signaling Increases Net Acid Extrusion, Proliferation and Invasion in Panc-1 Pancreatic Cancer Cells: SMAD4 Dependence and Link to Merlin/NF2 Signaling. Front Oncol 2020; 10:687. [PMID: 32457840 PMCID: PMC7221161 DOI: 10.3389/fonc.2020.00687] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 04/14/2020] [Indexed: 12/14/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is a major cause of cancer-related death, with a 5-year survival of <10% and severely limited treatment options. PDAC hallmarks include profound metabolic acid production and aggressive local proliferation and invasiveness. This phenotype is supported by upregulated net acid extrusion and epithelial-to-mesenchymal transition (EMT), the latter typically induced by aberrant transforming growth factor-β (TGFβ) signaling. It is, however, unknown whether TGFβ-induced EMT and upregulation of acid extrusion are causally related. Here, we show that mRNA and protein expression of the net acid extruding transporters Na+/H+ exchanger 1 (NHE1, SLC9A1) and Na+, HCO3- cotransporter 1 (NBCn1, SLC4A7) are increased in a panel of human PDAC cell lines compared to immortalized human pancreatic ductal epithelial (HPDE) cells. Treatment of Panc-1 cells (which express SMAD4, required for canonical TGFβ signaling) with TGFβ-1 for 48 h elicited classical EMT with down- and upregulation of epithelial and mesenchymal markers, respectively, in a manner inhibited by SMAD4 knockdown. Accordingly, less pronounced EMT was induced in BxPC-3 cells, which do not express SMAD4. TGFβ-1 treatment elicited a SMAD4-dependent increase in NHE1 expression, and a smaller, SMAD4-independent increase in NBCn1 in Panc-1 cells. Consistent with this, TGFβ-1 treatment led to elevated intracellular pH and increased net acid extrusion capacity in Panc-1 cells, but not in BxPC-3 cells, in an NHE1-dependent manner. Proliferation was increased in Panc-1 cells and decreased in BxPC-3 cells, upon TGFβ-1 treatment, and this, as well as EMT per se, was unaffected by NHE1- or NBCn1 inhibition. TGFβ-1-induced EMT was associated with a 4-fold increase in Panc-1 cell invasiveness, which further increased ~10-fold upon knockdown of the tumor suppressor Merlin (Neurofibromatosis type 2). Knockdown of NHE1 or NBCn1 abolished Merlin-induced invasiveness, but not that induced by TGFβ-1 alone. In conclusion, NHE1 and NBCn1 expression and NHE-dependent acid extrusion are upregulated during TGFβ-1-induced EMT of Panc-1 cells. NHE1 upregulation is SMAD4-dependent, and SMAD4-deficient BxPC-3 cells show no change in pHi regulation. NHE1 and NBCn1 are not required for EMT per se or EMT-associated proliferation changes, but are essential for the potentiation of invasiveness induced by Merlin knockdown.
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Affiliation(s)
- Raj R Malinda
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Katrine Zeeberg
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Patricia C Sharku
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Mette Q Ludwig
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Lotte B Pedersen
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Søren T Christensen
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Stine F Pedersen
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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7
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Keurhorst D, Liashkovich I, Frontzek F, Nitzlaff S, Hofschröer V, Dreier R, Stock C. MMP3 activity rather than cortical stiffness determines NHE1-dependent invasiveness of melanoma cells. Cancer Cell Int 2019; 19:285. [PMID: 31728131 PMCID: PMC6842528 DOI: 10.1186/s12935-019-1015-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 11/01/2019] [Indexed: 12/31/2022] Open
Abstract
Background Both cell adhesion and matrix metalloproteinase (MMP) activity depend on pH at the cell surface. By regulating extracellular juxtamembrane pH, the Na+/H+ exchanger NHE1 plays a significant part in human melanoma (MV3) cell migration and invasion. Because NHE1, besides its pH-regulatory transport function, also serves as a structural element tying the cortical actin cytoskeleton to the plasma membrane, we investigated whether NHE1 affects cortical stiffness of MV3 cells, and how this makes an impact on their invasiveness. Methods NHE1 overexpressing MV3 cells were compared to the corresponding mock-transfected control cells. NHE1 expression was verified by Western blotting, cariporide (HOE642) was used to inhibit NHE1 activity, cell stiffness was determined by atomic force microscopy, and F-actin was visualized by phalloidin-staining. Migration on, and invasion of, native and glutaraldehyde-fixed collagen I substrates were analyzed using time-lapse video microscopy and Boyden-chamber assays, respectively. MMP secretion and activity were detected by Western blot and zymography, respectively. MMP activity was inhibited with NNGH. Results The cortical, but not the bulk stiffness, was significantly higher in NHE1 overexpressing cells. This increase in cortical stiffness was accompanied by a reorganization of the cortical cytoskeleton, i.e. a condensation of F-actin underneath and along the plasma membrane. However, it was not affected by NHE1 inhibition. Nevertheless, actin dynamics is required for cell invasion as demonstrated with the application of cytochalasin D. NHE1 overexpression was associated with an elevated MMP3 secretion and an increase in the invasion of a native matrix. This increase in invasiveness could be antagonized by the MMP inhibitor NNGH. Transmigration through a glutaraldehyde-fixed, indigestible substrate was not affected by NHE1 overexpression. Conclusion NHE1, as a structural element and independently of its transport activity, contributes to the organization of the cortical F-actin meshwork and thus impacts cortical stiffness. Since NHE1 overexpression stimulates MMP3 secretion but does not change transmigration through a fixed substrate, MV3 cell invasion of a native substrate depends on MMP activity rather than on a modifiable cortical stiffness.
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Affiliation(s)
- Dennis Keurhorst
- 1Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, 48149 Münster, Germany
| | - Ivan Liashkovich
- 1Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, 48149 Münster, Germany
| | - Fabian Frontzek
- 2Department of Oncology and Hematology, University Hospital of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany
| | - Svenja Nitzlaff
- 3Institute of Animal Physiology, University of Münster, Schlossplatz 8, 48143 Münster, Germany
| | - Verena Hofschröer
- 1Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, 48149 Münster, Germany
| | - Rita Dreier
- 4Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Waldeyer-Str. 15, 48149 Münster, Germany
| | - Christian Stock
- 1Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, 48149 Münster, Germany.,5Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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Hofschröer V, Koch KA, Ludwig FT, Friedl P, Oberleithner H, Stock C, Schwab A. Extracellular protonation modulates cell-cell interaction mechanics and tissue invasion in human melanoma cells. Sci Rep 2017; 7:42369. [PMID: 28205573 PMCID: PMC5304230 DOI: 10.1038/srep42369] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 01/10/2017] [Indexed: 12/25/2022] Open
Abstract
Detachment of cells from the primary tumour precedes metastatic progression by
facilitating cell release into the tissue. Solid tumours exhibit altered pH
homeostasis with extracellular acidification. In human melanoma, the
Na+/H+ exchanger NHE1 is an important modifier of
the tumour nanoenvironment. Here we tested the modulation of cell-cell-adhesion by
extracellular pH and NHE1. MV3 tumour spheroids embedded in a collagen matrix
unravelled the efficacy of cell-cell contact loosening and 3D emigration into an
environment mimicking physiological confinement. Adhesive interaction strength
between individual MV3 cells was quantified using atomic force microscopy and
validated by multicellular aggregation assays. Extracellular acidification from
pHe7.4 to 6.4 decreases cell migration and invasion but increases
single cell detachment from the spheroids. Acidification and NHE1 overexpression
both reduce cell-cell adhesion strength, indicated by reduced maximum pulling forces
and adhesion energies. Multicellular aggregation and spheroid formation are strongly
impaired under acidification or NHE1 overexpression. We show a clear dependence of
melanoma cell-cell adhesion on pHe and NHE1 as a modulator. These effects
are opposite to cell-matrix interactions that are strengthened by protons extruded
via NHE1. We conclude that these opposite effects of NHE1 act synergistically during
the metastatic cascade.
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Affiliation(s)
| | | | | | - Peter Friedl
- Radboud University Medical Centre, Radboud Institute for Molecular Life Sciences, Department of Cell Biology, Nijmegen, The Netherlands.,David H. Koch Center for Applied Research of Genitourinary Cancers, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States.,Cancer Genomics Center, CG Utrecht, The Netherlands
| | | | - Christian Stock
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Albrecht Schwab
- Institute of Physiology II, University of Münster, Münster, Germany
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Stock C, Pedersen SF. Roles of pH and the Na +/H + exchanger NHE1 in cancer: From cell biology and animal models to an emerging translational perspective? Semin Cancer Biol 2016; 43:5-16. [PMID: 28007556 DOI: 10.1016/j.semcancer.2016.12.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 12/10/2016] [Indexed: 01/30/2023]
Abstract
Acidosis is characteristic of the solid tumor microenvironment. Tumor cells, because they are highly proliferative and anabolic, have greatly elevated metabolic acid production. To sustain a normal cytosolic pH homeostasis they therefore need to either extrude excess protons or to neutralize them by importing HCO3-, in both cases causing extracellular acidification in the poorly perfused tissue microenvironment. The Na+/H+ exchanger isoform 1 (NHE1) is a ubiquitously expressed acid-extruding membrane transport protein, and upregulation of its expression and/or activity is commonly correlated with tumor malignancy. The present review discusses current evidence on how altered pH homeostasis, and in particular NHE1, contributes to tumor cell motility, invasion, proliferation, and growth and facilitates evasion of chemotherapeutic cell death. We summarize data from in vitro studies, 2D-, 3D- and organotypic cell culture, animal models and human tissue, which collectively point to pH-regulation in general, and NHE1 in particular, as potential targets in combination chemotherapy. Finally, we discuss the possible pitfalls, side effects and cellular escape mechanisms that need to be considered in the process of translating the plethora of basic research data into a clinical setting.
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Affiliation(s)
- Christian Stock
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
| | - Stine Falsig Pedersen
- Department of Biology, Section for Cell Biology and Physiology, University of Copenhagen, Universitetsparken 13, 2100 Copenhagen, Denmark.
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Petrilli AM, Fernández-Valle C. Role of Merlin/NF2 inactivation in tumor biology. Oncogene 2016; 35:537-48. [PMID: 25893302 PMCID: PMC4615258 DOI: 10.1038/onc.2015.125] [Citation(s) in RCA: 271] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 02/20/2015] [Accepted: 03/16/2015] [Indexed: 01/13/2023]
Abstract
Merlin (Moesin-ezrin-radixin-like protein, also known as schwannomin) is a tumor suppressor protein encoded by the neurofibromatosis type 2 gene NF2. Loss of function mutations or deletions in NF2 cause neurofibromatosis type 2 (NF2), a multiple tumor forming disease of the nervous system. NF2 is characterized by the development of bilateral vestibular schwannomas. Patients with NF2 can also develop schwannomas on other cranial and peripheral nerves, as well as meningiomas and ependymomas. The only potential treatment is surgery/radiosurgery, which often results in loss of function of the involved nerve. There is an urgent need for chemotherapies that slow or eliminate tumors and prevent their formation in NF2 patients. Interestingly NF2 mutations and merlin inactivation also occur in spontaneous schwannomas and meningiomas, as well as other types of cancer including mesothelioma, glioma multiforme, breast, colorectal, skin, clear cell renal cell carcinoma, hepatic and prostate cancer. Except for malignant mesotheliomas, the role of NF2 mutation or inactivation has not received much attention in cancer, and NF2 might be relevant for prognosis and future chemotherapeutic approaches. This review discusses the influence of merlin loss of function in NF2-related tumors and common human cancers. We also discuss the NF2 gene status and merlin signaling pathways affected in the different tumor types and the molecular mechanisms that lead to tumorigenesis, progression and pharmacological resistance.
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Affiliation(s)
- Alejandra M. Petrilli
- Department of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, USA
| | - Cristina Fernández-Valle
- Department of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, USA
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