Volume-activated chloride channels contribute to cell-cycle-dependent regulation of HeLa cell migration

Pathophysiological role of ion channels and transporters in gastrointestinal mucosal diseases

The incidence of gastrointestinal (GI) mucosal diseases, including various types of gastritis, ulcers, inflammatory bowel disease and GI cancer, is increasing. Therefore, it is necessary to identify new therapeutic targets. Ion channels/transporters are located on cell membranes, and tight junctions (TJs) affect acid–base balance, the mucus layer, permeability, the microbiota and mucosal blood flow, which are essential for maintaining GI mucosal integrity. As ion channel/transporter dysfunction results in various GI mucosal diseases, this review focuses on understanding the contribution of ion channels/transporters to protecting the GI mucosal barrier and the relationship between GI mucosal disease and ion channels/transporters, including Cl⁻/HCO₃⁻ exchangers, Cl⁻ channels, aquaporins, Na⁺/H⁺ exchangers, and K⁺ channels. Here, we provide novel prospects for the treatment of GI mucosal diseases.

ClC-5 Downregulation Induces Osteosarcoma Cell Apoptosis by Promoting Bax and tBid Complex Formation

Osteosarcoma is the most common malignant bone tumor. Chloride (Cl^-) channels-mediated Cl^- movement plays an important role in regulating the functions of various cancer cells, but its role in osteosarcoma remains unclear. In this study, we found that ClC-5 was increased in osteosarcoma tissues compared with normal bone tissues. Patients with high ClC-5 expression showed poor overall survival relative to those patients with low ClC-5 expression. Higher ClC-5 expression and lower intracellular Cl^- concentration ([Cl^-]_i) were observed in osteosarcoma cells compared with normal osteoblasts. Lowering [Cl^-]_i increased the viability of osteosarcoma cells, which was markedly blocked by ClC-5 downregulation. Knockdown of ClC-5 significantly induced osteosarcoma cell apoptosis and increased the release of cytochrome c from mitochondria to cytosol, concomitantly with cleavage of caspase-9, caspase-3, and PARP. The effect of ClC-5 downregulation on osteosarcoma cell apoptosis and viability was abolished by caspase-3 and caspase-9 inhibitors, but not caspase-8 inhibitor. Furthermore, ClC-5 inhibition promoted Bax translocation from cytosol to mitochondria. Immunoprecipitation showed that ClC-5 interacted with Bax and ClC-5 downregulation enhanced Bax and tBid complex formation. Collectively, we demonstrate that ClC-5 downregulation induces osteosarcoma cell apoptosis via mitochondria-dependent apoptotic pathway activation by promoting Bax and tBid association and subsequent Bax translocation.

Volume-regulated chloride channel regulates cell proliferation and is involved in the possible interaction between TMEM16A and LRRC8A in human metastatic oral squamous cell carcinoma cells

OBJECTIVES

Volume-regulated anion channels (VRACs), expressed in various cells, play an important role in cell volume regulation. Despite being physiologically defined almost half a century ago, only the molecular candidates of VRAC, TMEM16A, LRRC8A, and bestrophin-1 (BEST1), are known. Here, we aimed to explore the functional significance of VRAC in, HST-1, an oral squamous cell carcinoma (OSCC) cell line.

METHODS

Cell proliferation assays, RT-PCR, Western blot, and flow cytometry were used to estimate changes in gene expression and cell proliferation. Ion channel activity was recorded using the patch-clamp technique. Specific genes were knocked-down by siRNA assays.

RESULTS

VRAC, identified as a hypotonicity-induced current, was highly functional and associated with the proliferation of HST-1 cells but not of HaCaT (a normal keratinocyte) cells. The pharmacological profile of VRAC in HST-1 was similar to that reported previously. DCPIB, a specific VRAC inhibitor, completely inhibited VRAC and proliferation of HST-1 cells, eventually leading to apoptosis. VRAC in HST-1 was attenuated by the knockdown of TMEM16A and LRRC8A, while knockdown of BEST1 affected cell proliferation. In situ proximity ligation assay showed that TMEM16A and LRRC8A co-localized under isotonic conditions (300 mOsM) but were separated under hypotonic conditions (250 mOsM) on the plasma membrane.

CONCLUSIONS

We have found that VRAC acts to regulate the proliferation of human metastatic OSCC cells and the composition of VRAC may involve in the interactions between TMEM16A and LRRC8A in HST-1 cells.

ClC-3/SGK1 regulatory axis enhances the olaparib-induced antitumor effect in human stomach adenocarcinoma

Currently, only a few available targeted drugs are considered to be effective in stomach adenocarcinoma (STAD) treatment. The PARP inhibitor olaparib is a molecularly targeted drug that continues to be investigated in BRCA-mutated tumors. However, in tumors without BRCA gene mutations, particularly in STAD, the effect and molecular mechanism of olaparib are unclear, which largely restricts the use of olaparib in STAD treatment. In this study, the in vitro results showed that olaparib specifically inhibited cell growth and migration, exerting antitumor effect in STAD cell lines. In addition, a ClC-3/SGK1 regulatory axis was identified and validated in STAD cells. We then found that the down-regulation of ClC-3/SGK1 axis attenuated olaparib-induced cell growth and migration inhibition. On the contrary, the up-regulation of ClC-3/SGK1 axis enhanced olaparib-induced cell growth and migration inhibition, and the enhancement effect could be attenuated by SGK1 knockdown. Consistently, the whole-cell recorded chloride current activated by olaparib presented the same variation trend. Next, the clinical data showed that ClC-3 and SGK1 were highly expressed in human STAD tissues and positively correlated (r = 0.276, P = 0.009). Furthermore, high protein expression of both ClC-3 (P = 0.030) and SGK1 (P = 0.006) was associated with poor survival rate in STAD patients, and positive correlations between ClC-3/SGK1 and their downstream molecules in STAD tissues were demonstrated via the GEPIA datasets. Finally, our results suggested that olaparib inhibited the PI3K/AKT pathway in STAD cells, and up-regulation of ClC-3/SGK1 axis enhanced olaparib-induced PI3K/AKT pathway inhibition. The animal experiments indicated that olaparib also exerted antitumor effect in vivo. Altogether, our findings illustrate that olaparib exerts antitumor effect in human STAD, and ClC-3/SGK1 regulatory axis enhances the olaparib-induced antitumor effect. Up-regulation of the ClC-3/SGK1 axis may provide promising therapeutic potential for the clinical application of olaparib in STAD treatment.

Icariside II suppresses cervical cancer cell migration through JNK modulated matrix metalloproteinase-2/9 inhibition in vitro and in vivo

Metastasis contributes a lot to cervical cancer high mortality rate. Icariside II is the principal component of Epimedium brevicornum Maxim and the major functional part to its therapeutic properties. However, the effects and mechanisms of Icariside II on cervical cancer metastasis remain unclear. Using female BALB/c mice with 60 mm³ tumors, we injected mice tail with 25 mg/kg body weight Icariside II or DMSO. After harvesting the tumor, immunohistochemistry and western blot were performed to detect MMP2/9 levels. Icariside II injection significantly inhibited MMP2/9 protein expression. The cell migration assays revealed that Icarisdie II inhibited the wound closure rate and the ability of Hela cell crossing the transwell chambers. Further, the key regulators in NF-κB and MAPK signaling pathway were detected in xenograft tumor and Hela cells by qPCR and western blot. JNK was screened out from several important signaling molecules, which had the same expression trend with MMP2/9. Finally, both 5 μM and 30 μM Icariside II weakened JNK-MMP2/9 signaling, despite the JNK activator Polyphyllin I and Anisomycin reversed the deficiencies. In this study, we proved that Icariside II can inhibit cervical cancer cells migration through JNK-MMP2/9 signaling pathway and is a prospective drug with high-chemopreventive effects on cervical cancer cell metastasis.

Ion Channels in The Pathogenesis of Endometriosis: A Cutting-Edge Point of View

BACKGROUND

Ion channels play a crucial role in many physiological processes. Several subtypes are expressed in the endometrium. Endometriosis is strictly correlated to estrogens and it is evident that expression and functionality of different ion channels are estrogen-dependent, fluctuating between the menstrual phases. However, their relationship with endometriosis is still unclear.

OBJECTIVE

To summarize the available literature data about the role of ion channels in the etiopathogenesis of endometriosis.

METHODS

A search on PubMed and Medline databases was performed from inception to November 2019.

RESULTS

Cystic fibrosis transmembrane conductance regulator (CFTR), transient receptor potentials (TRPs), aquaporins (AQPs), and chloride channel (ClC)-3 expression and activity were analyzed. CFTR expression changed during the menstrual phases and was enhanced in endometriosis samples; its overexpression promoted endometrial cell proliferation, migration, and invasion throughout nuclear factor kappa-light-chain-enhancer of activated B cells-urokinase plasminogen activator receptor (NFκB-uPAR) signaling pathway. No connection between TRPs and the pathogenesis of endometriosis was found. AQP5 activity was estrogen-increased and, through phosphatidylinositol-3-kinase and protein kinase B (PI3K/AKT), helped in vivo implantation of ectopic endometrium. In vitro, AQP9 participated in extracellular signal-regulated kinases/p38 mitogen-activated protein kinase (ERK/p38 MAPK) pathway and helped migration and invasion stimulating matrix metalloproteinase (MMP)2 and MMP9. ClC-3 was also overexpressed in ectopic endometrium and upregulated MMP9.

CONCLUSION

Available evidence suggests a pivotal role of CFTR, AQPs, and ClC-3 in endometriosis etiopathogenesis. However, data obtained are not sufficient to establish a direct role of ion channels in the etiology of the disease. Further studies are needed to clarify this relationship.

Antitumor effects of disulfiram/copper complex in the poorly-differentiated nasopharyngeal carcinoma cells via activating ClC-3 chloride channel

The enhancement of the anticancer activity by disulfiram (DSF) chelated with copper (DSF/Cu²⁺) has been investigated recently, while the underlying molecular mechanisms still need to be fully elucidated. Chloride channel-3 (ClC-3) is over-expressed in a variety of cancers and involves multiple tumor biological events. However, whether the over-expression of ClC-3 in tumor cells affects the sensitivity of anti-tumor drugs remains unclear. Here, we showed that the involvement of ClC-3 chloride channel in the selective cytotoxicity of DSF/Cu²⁺ in the poorly-differentiated nasopharyngeal carcinoma. The EC₅₀ of DSF alone and DSF/Cu²⁺ in activating the Cl^- channel were 95.36 μM and 0.31 μM in the CNE-2Z cells, respectively. DSF/Cu²⁺ exhibited a positive correlation between the induction of the Cl^- currents and the inhibition of cell proliferation. DSF/Cu²⁺ increased the ClC-3 protein expression and induced the cell apoptosis. Cl^- channel blockers, NPPB and DIDS, and ClC-3 siRNA partially inhibited the cell apoptosis, and depleted the Cl^- currents induced by DSF/Cu²⁺ in CNE-2Z cells. However, these effects could not be observed in the normal nasopharyngeal epithelium NP69-SV40 T cells. In vivo, the transplanted human nasopharyngeal carcinoma tumors size in the DSF/Cu²⁺ group decreased about 73.2% of those in the solvent control group. The chloride blockers partially inhibited the antitumor action of DSF/Cu²⁺. These data demonstrated that the selective cytotoxicity of DSF/Cu²⁺ may relate to its selective activation of ClC-3 Cl^- channel pathways in CNE-2Z cells. ClC-3 Cl^- channel can be viewed as a new and promising target for the treatment of nasopharyngeal carcinoma.

Overexpression of CLC-3 is regulated by XRCC5 and is a poor prognostic biomarker for gastric cancer

Background

Recently, many potential prognostic biomarkers for gastric cancer (GC) have been identified, but the prognosis of advanced GC patients remains poor. Chloride channels are promising cancer biomarkers, and their family member chloride channel-3 (CLC-3) is involved in multiple biological behaviors. However, whether CLC-3 is a prognostic biomarker for GC patients is rarely reported. The molecular mechanisms by which CLC-3 is regulated in GC are unclear.

Methods

The expression of CLC-3 and XRCC5 in human specimens was analyzed using immunohistochemistry. The primary biological functions and pathways related to CLC-3 were enriched by RNA sequencing. A 5′-biotin-labeled DNA probe with a promoter region between − 248 and + 226 was synthesized to pull down CLC-3 promoter-binding proteins. Functional studies were detected by MTS, clone formation, wound scratch, transwell, and xenograft mice model. Mechanistic studies were investigated by streptavidin-agarose-mediated DNA pull-down, mass spectrometry, ChIP, dual-luciferase reporter assay system, Co-IP, and immunofluorescence.

Results

The results showed that CLC-3 was overexpressed in human GC tissues and that overexpression of CLC-3 was a poor prognostic biomarker for GC patients (P = 0.012). Furthermore, higher expression of CLC-3 was correlated with deeper tumor invasion (P = 0.006) and increased lymph node metastasis (P = 0.016), and knockdown of CLC-3 inhibited cell proliferation and migration in vitro. In addition, X-ray repair cross-complementing 5 (XRCC5) was identified as a CLC-3 promoter-binding protein, and both CLC-3 (HR 1.671; 95% CI 1.012–2.758; P = 0.045) and XRCC5 (HR 1.795; 95% CI 1.076–2.994; P = 0.025) were prognostic factors of overall survival in GC patients. The in vitro and in vivo results showed that the expression and function of CLC-3 were inhibited after XRCC5 knockdown, and the inhibition effects were rescued by CLC-3 overexpression. Meanwhile, the expression and function of CLC-3 were promoted after XRCC5 overexpression, and the promotion effects were reversed by the CLC-3 knockdown. The mechanistic study revealed that knockdown of XRCC5 suppressed the binding of XRCC5 to the CLC-3 promoter and subsequent promoter activity, thus regulating CLC-3 expression at the transcriptional level by interacting with PARP1.

Conclusions

Our findings indicate that overexpression of CLC-3 is regulated by XRCC5 and is a poor prognostic biomarker for gastric cancer. Double targeting CLC-3 and XRCC5 may provide the promising therapeutic potential for GC treatment.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0660-y) contains supplementary material, which is available to authorized users.

CLC Chloride Channels and Transporters: Structure, Function, Physiology, and Disease

CLC anion transporters are found in all phyla and form a gene family of eight members in mammals. Two CLC proteins, each of which completely contains an ion translocation parthway, assemble to homo- or heteromeric dimers that sometimes require accessory β-subunits for function. CLC proteins come in two flavors: anion channels and anion/proton exchangers. Structures of these two CLC protein classes are surprisingly similar. Extensive structure-function analysis identified residues involved in ion permeation, anion-proton coupling and gating and led to attractive biophysical models. In mammals, ClC-1, -2, -Ka/-Kb are plasma membrane Cl−channels, whereas ClC-3 through ClC-7 are 2Cl−/H+-exchangers in endolysosomal membranes. Biological roles of CLCs were mostly studied in mammals, but also in plants and model organisms like yeast and Caenorhabditis elegans. CLC Cl−channels have roles in the control of electrical excitability, extra- and intracellular ion homeostasis, and transepithelial transport, whereas anion/proton exchangers influence vesicular ion composition and impinge on endocytosis and lysosomal function. The surprisingly diverse roles of CLCs are highlighted by human and mouse disorders elicited by mutations in their genes. These pathologies include neurodegeneration, leukodystrophy, mental retardation, deafness, blindness, myotonia, hyperaldosteronism, renal salt loss, proteinuria, kidney stones, male infertility, and osteopetrosis. In this review, emphasis is laid on biophysical structure-function analysis and on the cell biological and organismal roles of mammalian CLCs and their role in disease.

Knockdown of Chloride Channel-3 Inhibits Breast Cancer Growth In Vitro and In Vivo

Purpose

Chloride channel-3 (ClC-3) is a member of the chloride channel family and plays a critical role in a variety of cellular activities. The aim of the present study is to explore the molecular mechanisms underlying the antitumor effect of silencing ClC-3 in breast cancer.

Methods

Human breast cancer cell lines MDA-MB-231 and MCF-7 were used in the experiments. Messenger RNA and protein expression were examined by quantitative real-time polymerase chain reaction and western blot analysis. Cell proliferation was measured by the bromodeoxyuridine method, and the cell cycle was evaluated using fluorescence-activated cell sorting. Protein interaction in cells was analyzed by co-immunoprecipitation. Tumor tissues were stained with hematoxylin-eosin and tumor burden was measured using the Metamorph software.

Results

Breast cancer tissues collected from patients showed an increase in ClC-3 expression. Knockdown of ClC-3 inhibited the secretion of insulin-like growth factor (IGF)-1, cell proliferation, and G1/S transition in breast cancer cells. In the mouse xenograft model of human breast carcinoma, tumor growth was significantly slower in animals injected with ClC-3-deficient cells compared with the growth of normal human breast cancer cells. In addition, silencing of ClC-3 attenuated the expression of proliferating cell nuclear antigen, Ki-67, cyclin D1, and cyclin E, as well as the activation of extracellular signalregulated protein kinases (ERK) 1/2, both in vitro and in vivo.

Conclusion

Together, our data suggest that upregulation of ClC-3 by IGF-1 contributes to cell proliferation and tumor growth in breast cancer, and ClC-3 deficiency suppresses cell proliferation and tumor growth via the IGF/IGF receptor/ERK pathway.

Overexpression of chloride channel-3 predicts unfavorable prognosis and promotes cellular invasion in gastric cancer

BACKGROUND

Chloride channel-3 (CLC-3) has been reported to promote the proliferation and invasion in various tumors, yet little is known about its role in gastric cancer. In the present study, we investigated the clinical significance of CLC-3 and its biological role in gastric cancer.

METHODS

Bioinformatic analysis, immunohistochemical staining, quantitative real-time polymerase chain reaction and Western blot assay were used to assess the expression of CLC-3 and its clinical significance in gastric cancer. The biological role of CLC-3 and its underlying mechanism were detected through in vitro experiments.

RESULTS

CLC-3 was highly expressed in gastric cancer tissues and cell lines, and high levels of CLC-3 were significantly associated with adverse clinicopathological parameters and shorter overall survival time in patients with gastric cancer. Functional studies revealed that silencing of CLC-3 decreased, while overexpression promoted, the proliferation, migration and invasion of gastric cancer cells in vitro. Mechanistic studies suggested that canonical TGF-β/Smad signaling pathway is involved in CLC-3-induced gastric cancer cells proliferation, migration and invasion.

CONCLUSION

These findings indicate the vital role of CLC-3 in gastric cancer progression and its potential role of a therapeutic target for treatment.

Ion channel signaling influences cellular proliferation and phagocyte activity during axolotl tail regeneration

Little is known about the potential for ion channels to regulate cellular behaviors during tissue regeneration. Here, we utilized an amphibian tail regeneration assay coupled with a chemical genetic screen to identify ion channel antagonists that altered critical cellular processes during regeneration. Inhibition of multiple ion channels either partially (anoctamin1/Tmem16a, anoctamin2/Tmem16b, KV2.1, KV2.2, L-type CaV channels and H/K ATPases) or completely (GlyR, GABAAR, KV1.5 and SERCA pumps) inhibited tail regeneration. Partial inhibition of tail regeneration by blocking the calcium activated chloride channels, anoctamin1&2, was associated with a reduction of cellular proliferation in tail muscle and mesenchymal regions. Inhibition of anoctamin 1/2 also altered the post-amputation transcriptional response of p44/42 MAPK signaling pathway genes, including decreased expression of erk1/erk2. We also found that complete inhibition via voltage gated K+ channel blockade was associated with diminished phagocyte recruitment to the amputation site. The identification of H+ pumps as required for axolotl tail regeneration supports findings in Xenopus and Planaria models, and more generally, the conservation of ion channels as regulators of tissue regeneration. This study provides a preliminary framework for an in-depth investigation of the mechanistic role of ion channels and their potential involvement in regulating cellular proliferation and other processes essential to wound healing, appendage regeneration, and tissue repair.

Activation of ClC-3 chloride channel by 17β-estradiol relies on the estrogen receptor α expression in breast cancer

Although extensively studied, the mechanisms by which estrogen promotes breast cancer growth remain to be fully elucidated. Tamoxifen, an antiestrogen agent to treat ERα+ breast cancer, is also a high-affinity blocker of the chloride channels. In this study, we explored the involvement of the chloride channels in the action of estrogen in breast cancer. We found that 17β-estradiol (17β-E2) concentration-dependently activated the chloride currents in ERα+ breast cancer MCF-7 cells. Extracellular hypertonic challenge and chloride channel blockers, NPPB and DIDS inhibited the 17β-E2-activated chloride currents. Decreased the ClC-3 protein expression caused the depletion of the 17β-E2-activated chloride currents. 17β-E2-activated chloride currents which relied on the ERα expression were demonstrated by the following evidences. Firstly, 17β-E2-activated chloride currents could not be observed in ERα- breast cancer MDA-MB-231 cells. Secondly, ER antagonists, tamoxifen and ICI 182,780, and downregulation of ERα expression inhibited or abolished the 17β-E2-activated chloride currents. Thirdly, ERα expression was induced in MDA-MB-231 cells by ESR1 gene transfection, and then 17β-E2-activated chloride currents could be observed. In MCF-7 cells, ERα and ClC-3 mainly located in nucleus and translocated to cell plasma and membrane with respect to co-localization following treatment of 17β-E2. Downregulation of ERα expression could decrease the expression of ClC-3 protein. Conversely, downregulation of ClC-3 expression did not influence the ERα expression. Taken together, our findings demonstrated that ClC-3 is a potential target of 17β-E2 and is modulated by the ERα in breast cancer cell. Pharmacological modulation of ClC-3 may provide a deep understanding in antiestrogen treatment of breast cancer patients.

Dynamic properties of calcium-activated chloride currents in Xenopus laevis oocytes

Chloride is the most abundant permeable anion in the cell, and numerous studies in the last two decades highlight the great importance and broad physiological role of chloride currents mediated anion transport. They participate in a multiplicity of key processes, as for instance, the regulation of electrical excitability, apoptosis, cell cycle, epithelial secretion and neuronal excitability. In addition, dysfunction of Cl⁻ channels is involved in a variety of human diseases such as epilepsy, osteoporosis and different cancer types. Historically, chloride channels have been of less interest than the cation channels. In fact, there seems to be practically no quantitative studies of the dynamics of chloride currents. Here, for the first time, we have quantitatively studied experimental calcium-activated chloride fluxes belonging to Xenopus laevis oocytes, and the main results show that the experimental Cl⁻ currents present an informational structure characterized by highly organized data sequences, long-term memory properties and inherent “crossover” dynamics in which persistent correlations arise at short time intervals, while anti-persistent behaviors become dominant in long time intervals. Our work sheds some light on the understanding of the informational properties of ion currents, a key element to elucidate the physiological functional coupling with the integrative dynamics of metabolic processes.

Lipophilic but not hydrophilic statin functionally inhibit volume-activated chloride channels by inhibiting NADPH oxidase in monocytes

Volume-activated Cl^- channels (VACCs) can be activated by hypotonic solutions and have been identified in many cell types. Here, we investigated the effects of different statins on VACCs in monocytes. Whole-cell patch clamp recordings demonstrated that a hypotonic solution induced 5-nitro-2- (3-phenylpropylamino) benzoic acid (NPPB)- and 4,4'-diisothiocyanatostilbene-2, 2'-disulfonic acid (DIDS)-sensitive VACC currents in human peripheral monocytes and RAW 264.7 cells. The VACC currents were inhibited by the lipophilic statin (simvastatin) but not by the hydrophilic simvastatin acid and pravastatin. A low-molecular-weight superoxide anion scavenger (tiron, 1 mM) and inhibitor of NADPH oxidase (DPI 10 μM) was able to abolish the VACC currents. A hypotonic solution increased the reactive oxygen species (ROS) detected by the fluorescence of dichlorodihydrofluorescein (DCF), which was abolished by tiron and DPI. NPPB, DIDS, and simvastatin but not pravastatin decreased the fluorescence of DCF. Simvastatin could not further decrease VACC currents when pretreated with tiron or DPI, whereas exogenous H₂O₂ (100 μM), increased the VACC currents and overcame the blockade of VACC currents by simvastatin. Functionally, hypotonic solution increased the TNF-α mRNA expression, which could be decreased by tiron, DPI, NPPB, DIDS and simvastatin but not pravastatin. However, simvastatin could not decrease the TNF-α expression further when pretreatment with tiron, DPI, NPPB or DIDS. We conclude that lipophilic (simvastatin) rather than hydrophilic statin inhibit VACCs and decrease hyposmolality induced inflammation in monocytes by inhibiting NADPH oxidase.

Rinsing with Saline Promotes Human Gingival Fibroblast Wound Healing In Vitro

Rinsing the mouth with sodium chloride (NaCl) solution is believed to promote healthy gum and improve oral ulcer healing. Scientific evidence to support this assumption is, however, lacking. This study aims to investigate the effect and clarify underlying mechanisms of short-term rinsing with NaCl on human gingival fibroblast (hGFs) wound healing. Isolated primary hGFs and human normal oral keratinocytes (hNOKs) were rinsed with 0–7.2% NaCl for 2 min, 3 times a day. Scratch-tests, trans-well migration assays and MTT activity were performed. mRNA expression was assessed of type-I collagen, fibronectin and FAK. Changes in FAK and F-actin were detected by immunofluorescence. KCl, NaH₂PO₄, KH₂PO₄ were used to clarify the molecules involved. Rinsing with 0.9–1.8% NaCl significantly promoted hGFs cell migration but not proliferation. However, it had no effect on hNOKs. Rinsing with 1.8% NaCl significantly up-regulated the expression of type-I collagen and fibronectin. FAK and F-actin, molecules responsible for cytoskeleton re-organization and cell migration, were also up-regulated. Cl^- seemed to be essential since rinsing with KCl resulted in a similar effect as noted with NaCl. In conclusion, short-term rinsing with NaCl promoted hGFs migration, and increased the expression of extracellular matrix as well as cytoskeletal proteins. These data strongly support the long held belief in the benefits of using NaCl mouth-rinse.

Overexpression of chloride channel-3 is associated with the increased migration and invasion ability of ectopic endometrial cells from patients with endometriosis

STUDY QUESTION

Is chloride channel-3 (ClC-3) involved in regulating the biological behavior of endometrial stromal cells (ESCs)?

SUMMARY ANSWER

ClC-3 promotes endometriotic cell migration and invasion.

WHAT IS KNOWN ALREADY

ClC-3 plays a significant role in the migration and invasion of various kinds of cells.

STUDY DESIGN, SIZE, DURATION

An ITALIC! in vitro investigation of the effect of ClC-3 on the migration and invasion of ectopic ESCs from patients with endometriosis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The ectopic and eutopic endometrial samples from 43 female patients with endometriosis and the endometrial samples from 39 non-endometriotic female patients were collected. Primary cells from these samples were isolated and cultured. Real-time RT-PCR, immunohistochemistry and western blot were used to detect the expression of ClC-3 and matrix metalloproteinase 9 (MMP-9). Small interfering RNA (siRNA) technology was employed to knock down ClC-3 expression. The migration and invasion ability of ESCs was measured by the transwell assay with uncoated or Matrigel-coated membranes.

MAIN RESULTS AND THE ROLE OF CHANCE

The expression of ClC-3 mRNA and proteins was significantly up-regulated in the ectopic tissues from endometriotic patients, while that in the eutopic endometrial tissues of the same patients did not significantly differ from that in non-endometriotic patients. The migration and invasion ability and MMP-9 expression was increased in the ESCs from ectopic endometrial tissues. The knockdown of ClC-3 expression by ClC-3 siRNA inhibited ESC migration and invasion and attenuated the expression of MMP-9. ClC-3 expression level was well-correlated to the clinical characteristics and symptoms of endometriosis patients, including infertility, dysmenorrhea, chronic pelvic pain, dyspareunia and diameter of endometriosis lesion.

LIMITATIONS, REASONS FOR CAUTION

Further studies are needed to examine the regulatory mechanism of estrogen on ClC-3 expression of ESCs.

WIDER IMPLICATIONS OF THE FINDINGS

ClC-3 is involved in the migration and invasion processes of ESCs and can regulate MMP-9 expression. Up-regulation of ClC-3 expression may contribute to endometriosis development by regulating MMP-9 expression.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the National Natural Science Foundation of China (81173064, 81272223, 81273539), the Ministry of Education of China (20124401110009), the Natural Science Foundation of Guangdong Province (S2011010001589) and the Science and Technology Programs of Guangdong (2013B051000059), Guangzhou (2013J500015) and Dongguan (2011108102006). The authors have no conflict of interest.

Chloride channel-3 promotes tumor metastasis by regulating membrane ruffling and is associated with poor survival

The chloride channel-3 (ClC-3) protein is known to be a component of Cl⁻ channels involved in cell volume regulation or acidification of intracellular vesicles. Here, we report that ClC-3 was highly expressed in the cytoplasm of metastatic carcinomatous cells and accelerated cell migration in vitro and tumor metastasis in vivo. High-grade expression of cytoplasmic ClC-3 predicted poor survival in cancer patients. We found that independent of its volume-activated Cl⁻ channel properties, ClC-3 was able to promote cell membrane ruffling, required for tumor metastasis. ClC-3 mediated membrane ruffling by regulating keratin 18 phosphorylation to control β1 Integrin recycling. Therefore, cytoplasmic ClC-3 plays an active and key role in tumor metastasis and may be a valuable prognostic biomarker and a therapeutic target to prevent tumor spread.

Neuronal ClC-3 Splice Variants Differ in Subcellular Localizations, but Mediate Identical Transport Functions

ClC-3 is a member of the CLC family of anion channels and transporters, for which multiple functional properties and subcellular localizations have been reported. Since alternative splicing often results in proteins with diverse properties, we investigated to what extent alternative splicing might influence subcellular targeting and function of ClC-3. We identified three alternatively spliced ClC-3 isoforms, ClC-3a, ClC-3b, and ClC-3c, in mouse brain, with ClC-3c being the predominant splice variant. Whereas ClC-3a and ClC-3b are present in late endosomes/lysosomes, ClC-3c is targeted to recycling endosomes via a novel N-terminal isoleucine-proline (IP) motif. Surface membrane insertion of a fraction of ClC-3c transporters permitted electrophysiological characterization of this splice variant through whole-cell patch clamping on transfected mammalian cells. In contrast, neutralization of the N-terminal dileucine-like motifs was required for functional analysis of ClC-3a and ClC-3b. Heterologous expression of ClC-3a or ClC-3b carrying mutations in N-terminal dileucine motifs as well as WTClC-3c in HEK293T cells resulted in outwardly rectifying Cl(-) currents with significant capacitive current components. We conclude that alternative splicing of Clcn3 results in proteins with different subcellular localizations, but leaves the transport function of the proteins unaffected.

High glucose inhibits ClC-2 chloride channels and attenuates cell migration of rat keratinocytes

Background

Accumulating evidence has demonstrated that migration of keratinocytes is critical to wound epithelialization, and defects of this function result in chronic delayed-healing wounds in diabetes mellitus patients, and the migration has been proved to be associated with volume-activated chloride channels. The aim of the study is to investigate the effects of high glucose (HG, 25 mM) on ClC-2 chloride channels and cell migration of keratinocytes.

Methods

Newborn Sprague Dawley rats were used to isolate and culture the keratinocyte in this study. Immunofluorescence assay, real-time polymerase chain reaction, and Western blot assay were used to examine the expression of ClC-2 protein or mRNA. Scratch wound assay was used to measure the migratory ability of keratinocytes. Transwell cell migration assay was used to measure the invasion and migration of keratinocytes. Recombinant lentivirus vectors were established and transducted to keratinocytes. Whole-cell patch clamp was used to perform the electrophysiological studies.

Results

We found that the expression of ClC-2 was significantly inhibited when keratinocytes were exposed to a HG (25 mM) medium, accompanied by the decline of volume-activated Cl⁻ current (I_Cl,vol), migration potential, and phosphorylated PI3K as compared to control group. When knockdown of ClC-2 by RNAi or pretreatment with wortmannin, similar results were observed, including I_Cl,vol and migration keratinocytes were inhibited.

Conclusion

Our study proved that HG inhibited ClC-2 chloride channels and attenuated cell migration of rat keratinocytes via inhibiting PI3K signaling.

Does aberrant membrane transport contribute to poor outcome in adult acute myeloid leukemia?

Acute myeloid leukemia in adults is a highly heterogeneous disease. Gene expression profiling performed using unsupervised algorithms can be used to distinguish specific groups of patients within a large patient cohort. The identified gene expression signatures can offer insights into underlying physiological mechanisms of disease pathogenesis. Here, the analysis of several related gene expression clusters associated with poor outcome, worst overall survival and highest rates of resistant disease and obtained from the patients at the time of diagnosis or from previously untreated individuals is presented. Surprisingly, these gene clusters appear to be enriched for genes corresponding to proteins involved in transport across membranes (transporters, carriers and channels). Several ideas describing the possible relationship of membrane transport activity and leukemic cell biology, including the "Warburg effect," the specific role of chloride ion transport, direct "import" of metabolic energy through uptake of creatine phosphate, and modification of the bone marrow niche microenvironment are discussed.

Bioelectrical regulation of cell cycle and the planarian model system

Cell cycle regulation through the manipulation of endogenous membrane potentials offers tremendous opportunities to control cellular processes during tissue repair and cancer formation. However, the molecular mechanisms by which biophysical signals modulate the cell cycle remain underappreciated and poorly understood. Cells in complex organisms generate and maintain a constant voltage gradient across the plasma membrane known as the transmembrane potential. This potential, generated through the combined efforts of various ion transporters, pumps and channels, is known to drive a wide range of cellular processes such as cellular proliferation, migration and tissue regeneration while its deregulation can lead to tumorigenesis. These cellular regulatory events, coordinated by ionic flow, correspond to a new and exciting field termed molecular bioelectricity. We aim to present a brief discussion on the biophysical machinery involving membrane potential and the mechanisms mediating cell cycle progression and cancer transformation. Furthermore, we present the planarian Schmidtea mediterranea as a tractable model system for understanding principles behind molecular bioelectricity at both the cellular and organismal level. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

Chloride channels in cancer: Focus on chloride intracellular channel 1 and 4 (CLIC1 AND CLIC4) proteins in tumor development and as novel therapeutic targets

In recent decades, growing scientific evidence supports the role of ion channels in the development of different cancers. Both potassium selective pores and chloride permeabilities are considered the most active channels during tumorigenesis. High rate of proliferation, active migration, and invasiveness into non-neoplastic tissues are specific properties of neoplastic transformation. All these actions require partial or total involvement of chloride channel activity. In this context, this class of membrane proteins could represent valuable therapeutic targets for the treatment of resistant tumors. However, this encouraging premise has not so far produced any valid new channel-targeted antitumoral molecule for cancer treatment. Problematic for drug design targeting ion channels is their vital role in normal cells for essential physiological functions. By targeting these membrane proteins involved in pathological conditions, it is inevitable to cause relevant side effects in healthy organs. In light of this, a new protein family, the chloride intracellular channels (CLICs), could be a promising class of therapeutic targets for its intrinsic individualities: CLIC1 and CLIC4, in particular, not only are overexpressed in specific tumor types or their corresponding stroma but also change localization and function from hydrophilic cytosolic to integral transmembrane proteins as active ionic channels or signal transducers during cell cycle progression in certain cases. These changes in intracellular localization, tissue compartments, and channel function, uniquely associated with malignant transformation, may offer a unique target for cancer therapy, likely able to spare normal cells. This article is part of a special issue itled "Membrane Channels and Transporters in Cancers."

Functional expression of chloride channels and their roles in the cell cycle and cell proliferation in highly differentiated nasopharyngeal carcinoma cells

We previously demonstrated that the growth of the poorly differentiated nasopharyngeal carcinoma cells (CNE‐2Z) was more dependent on the activities of volume‐activated chloride channels than that of the normal nasopharyngeal epithelial cells (NP69‐SV40T). However, the activities and roles of such volume‐activated chloride channels in highly differentiated nasopharyngeal carcinoma cells (CNE‐1) are not clarified. In this study, it was found that a volume‐activated chloride current and a regulatory volume decrease (RVD) were induced by 47% hypotonic challenges. The current density and the capacity of RVD in the highly differentiated CNE‐1 cells were lower than those in the poorly differentiated CNE‐2Z cells, and higher than those in the normal cells (NP69‐SV40T). The chloride channel blockers, 5‐nitro‐2‐(3‐phenylpropylamino) benzoic acid (NPPB) and tamoxifen inhibited the current and RVD. Depletion of intracellular Cl⁻ abolished the RVD. The chloride channel blockers reversibly inhibited cell proliferation in a concentration‐ and time‐dependent manner, and arrested cells at the G0/G1 phases, but did not change cell viability. The sensitivity of the three cell lines to the chloride channel blockers was different, with the highest in poorly differentiated cells (CNE‐2Z) and the lowest in the normal cells (NP69‐SV40T). ClC‐3 proteins were expressed in the three cells and distributed inside the cells as well as on the cell membrane. In conclusion, the highly differentiated nasopharyngeal carcinoma CNE‐1 cells functionally expressed the volume‐activated chloride channels, which may play important roles in controlling cell proliferation through modulating the cell cycle, and may be associated with cell differentiation. Chloride channels may be a potential target of anticancer therapy.

In this paper, we demonstrated that the volume‐activated chloride channels were involved in regulating CNE‐1 cells proliferation and cell cycle progress. Thus, volume‐activated chloride channels may be a potential target of anticancer therapy.

The Ca(2+) -activated Cl(-) channel, ANO1 (TMEM16A), is a double-edged sword in cell proliferation and tumorigenesis

Since anoctamin 1 ANO1 (TMEM16A) was found to be a molecular component of Ca²⁺-activated Cl⁻ channels, its role in tumorigenesis has gained attention at a fast pace. ANO1 overexpression frequently occurs in the cancer tissues along with 11q13 chromosome amplification. Poor prognosis of many types of cancers has been closely correlated with ANO1 gene amplification and protein overexpression. ANO1 is now considered an excellent biomarker for certain cancers. Recent research suggests that it is the channel function of ANO1 that is involved in the tumorigenesis. However, how the overexpression of the functional ANO1 causes malignant transformation of tissues via signaling pathways, for example, MAPK remains to be investigated. Clarification of the reasons in future will avail to make ANO1 as a target for cancer treatment.

Roles of ion transport in control of cell motility

Cell motility is an essential feature of life. It is essential for reproduction, propagation, embryonic development, and healing processes such as wound closure and a successful immune defense. If out of control, cell motility can become life-threatening as, for example, in metastasis or autoimmune diseases. Regardless of whether ciliary/flagellar or amoeboid movement, controlled motility always requires a concerted action of ion channels and transporters, cytoskeletal elements, and signaling cascades. Ion transport across the plasma membrane contributes to cell motility by affecting the membrane potential and voltage-sensitive ion channels, by inducing local volume changes with the help of aquaporins and by modulating cytosolic Ca(2+) and H(+) concentrations. Voltage-sensitive ion channels serve as voltage detectors in electric fields thus enabling galvanotaxis; local swelling facilitates the outgrowth of protrusions at the leading edge while local shrinkage accompanies the retraction of the cell rear; the cytosolic Ca(2+) concentration exerts its main effect on cytoskeletal dynamics via motor proteins such as myosin or dynein; and both, the intracellular and the extracellular H(+) concentration modulate cell migration and adhesion by tuning the activity of enzymes and signaling molecules in the cytosol as well as the activation state of adhesion molecules at the cell surface. In addition to the actual process of ion transport, both, channels and transporters contribute to cell migration by being part of focal adhesion complexes and/or physically interacting with components of the cytoskeleton. The present article provides an overview of how the numerous ion-transport mechanisms contribute to the various modes of cell motility.

Tamoxifen inhibits migration of estrogen receptor-negative hepatocellular carcinoma cells by blocking the swelling-activated chloride current

Tamoxifen is a triphenylethylene non-steroidal antiestrogen anticancer agent. It also shows inhibitory effects on metastasis of estrogen receptor (EsR)-independent tumors, but the underlying mechanism is unclear. It was demonstrated in this study that, in EsR-negative and highly metastatic human hepatocellular carcinoma MHCC97H cells, tamoxifen-inhibited cell migration, volume-activated Cl(-) currents (I(Cl,vol)) and regulatory volume decrease (RVD) in a concentration-dependent manner with a similar IC(50). Analysis of the relationships between migration, I(Cl,vol) and RVD showed that cell migration was positively correlated with I(Cl,vol) and RVD. Knockdown of the expression of ClC-3 Cl(-) channel proteins by ClC-3 shRNA or siRNA inhibited I(Cl,vol), and cell migration, and these inhibitory effects could not be increased further by addition of tamoxifen in the medium. The results suggest that knockdown of ClC-3 expression may deplete the effects of tamoxifen; tamoxifen may inhibit cell migration by modulating I(Cl,vol) and cell volume. Moreover, tamoxifen decreased the activity of protein kinase C (PKC) and the effects were reversed by the PKC activator PMA. Activation of PKC by PMA could competitively downregulate the inhibitory effects of tamoxifen on I(Cl,vol). PMA promoted cell migration, and knockdown of ClC-3 expression by ClC-3 siRNA abolished the PMA effect on cell migration. The results suggest that tamoxifen may inhibit I(Cl,vol) by suppressing PKC activation; I(Cl,vol) may be an EsR-independent target for tamoxifen in the anti-metastatic action on cancers, especially on EsR-negative cancers. The finding may have an implication in the clinical use of tamoxifen in the treatments of both EsR-positive and EsR-negative cancers.

Role of ion channels and transporters in cell migration

Cell motility is central to tissue homeostasis in health and disease, and there is hardly any cell in the body that is not motile at a given point in its life cycle. Important physiological processes intimately related to the ability of the respective cells to migrate include embryogenesis, immune defense, angiogenesis, and wound healing. On the other side, migration is associated with life-threatening pathologies such as tumor metastases and atherosclerosis. Research from the last ≈ 15 years revealed that ion channels and transporters are indispensable components of the cellular migration apparatus. After presenting general principles by which transport proteins affect cell migration, we will discuss systematically the role of channels and transporters involved in cell migration.

ClC-3 is a candidate of the channel proteins mediating acid-activated chloride currents in nasopharyngeal carcinoma cells

Acid-activated chloride currents have been reported in several cell types and may play important roles in regulation of cell function. However, the molecular identities of the channels that mediate the currents are not defined. In this study, activation of the acid-induced chloride current and the possible candidates of the acid-activated chloride channel were investigated in human nasopharyngeal carcinoma cells (CNE-2Z). A chloride current was activated when extracellular pH was reduced to 6.6 from 7.4. However, a further decrease of extracellular pH to 5.8 inhibited the current. The current was weakly outward-rectified and was suppressed by hypertonicity-induced cell shrinkage and by the chloride channel blockers 5-nitro-2–3-phenylpropylamino benzoic acid (NPPB), tamoxifen, and 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid disodium salt hydrate (DIDS). The permeability sequence of the channel to anions was I− > Br− > Cl− > gluconate−. Among the ClC chloride channels, ClC-3 and ClC-7 were strongly expressed in CNE-2Z cells. Knockdown of ClC-3 expression with ClC-3 small interfering (si)RNA prevented the activation of the acid-induced current, but silence of ClC-7 expression with ClC-7 siRNA did not significantly affect the current. The results suggest that the chloride channel mediating the acid-induced chloride current was volume sensitive. ClC-3 is a candidate of the channel proteins that mediate or regulate the acid-activated chloride current in nasopharyngeal carcinoma cells.

Cell cycle-dependent subcellular distribution of ClC-3 in HeLa cells

Chloride channel-3 (ClC-3) is suggested to be a component and/or a regulator of the volume-activated Cl(-) channel in the plasma membrane. However, ClC-3 is predominantly located inside cells and the role of intracellular ClC-3 in tumor growth is unknown. In this study, we found that the subcellular distribution of endogenous ClC-3 varied in a cell cycle-dependent manner in HeLa cells. During interphase, ClC-3 was distributed throughout the cell and it accumulated at various positions in different stages. In early G1, ClC-3 was mainly located in the nucleus. In middle G1, ClC-3 gathered around the nuclear periphery as a ring. In late G1, ClC-3 moved back into the nucleus, where it remained throughout S phase. In G2, ClC-3 was concentrated in the cytoplasm. When cells progressed from G2 to the prophase of mitosis, ClC-3 from the cytoplasm translocated into the nucleus. During metaphase and anaphase, ClC-3 was distributed throughout the cell except for around the chromosomes and was aggregated at the spindle poles and in between two chromosomes, respectively. ClC-3 was then again concentrated in the nucleus upon the progression from telophase to cytokinesis. These results reveal a cell cycle-dependent change of the subcellular distribution of ClC-3 and strongly suggest that ClC-3 has nucleocytoplasmic shuttling dynamics that may play key regulatory roles during different stages of the cell cycle in tumor cells.

Hydrodynamic cellular volume changes enable glioma cell invasion

Malignant gliomas are highly invasive brain tumors that currently lack effective treatment. Unlike other cancers, gliomas do not metastasize via the vasculature but invade surrounding brain solely along extracellular routes, primarily moving along the vasculature and nerve tracts. This study uses several model systems to visualize and quantitatively assess cell volume changes of human glioma cells invading within the brain's extracellular space of C.B.17 severe combined immunodeficient (scid) mice and tumor cells invading in a modified Boyden chamber using three-dimensional multiphoton and confocal time-lapse microscopy. Regardless of model system used to quantitatively assess volume changes, invading glioma cells maximally decreased their volume by 30-35%, a value that was independent of barrier and cell size. Through osmotic challenges, we demonstrate that the observed cellular volume changes during invasion represent the smallest achievable cell volume and require glioma cells to release all free unbound cytoplasmic water. Water osmotically follows the release of Cl(-) through ion channels and cotransporters and blockade of Cl(-) flux inhibits both volume changes and cell invasion. Hence, invading glioma cells use hydrodynamic volume changes to meet the spatial constraints imposed within the brain, using essentially all free, unbound cytoplasmic water to maximally alter their volume as they invade.

Volume-sensitive chloride channels are involved in maintenance of basal cell volume in human acute lymphoblastic leukemia cells

Chloride channels are expressed ubiquitously in different cells. However, the activation and roles of volume-activated chloride channels under normal isotonic conditions are not clarified, especially in lymphatic cells. In this study, the activation of basal and volume-activated chloride currents and their roles in maintenance of basal cell volume under isotonic conditions were investigated in human acute lymphoblastic leukemia Molt4 cells. The patch-clamp technique and time-lapse image analysis were employed to record whole-cell currents and cell volume changes. Under isotonic conditions, a basal chloride current was recorded. The current was weakly outward-rectified and volume-sensitive and was not inactivated obviously in the observation period. A 47% hypertonic bath solution and the chloride channel blockers NPPB and tamoxifen suppressed the current. Exposure of cells to 47% hypotonic bath solution activated further the basal current. The hypotonicity-activated current possessed properties similar to those of the basal current and was inhibited by NPPB, tamoxifen, ATP and hypertonic bath solution. Furthermore, extracellular hypotonic challenges swelled the cells and induced a regulatory volume decrease (RVD). Extracellular applications of NPPB, tamoxifen and ATP swelled the cells under isotonic conditions and inhibited the RVD induced by hypotonic cell swelling. The results suggest that some volume-activated chloride channels are activated under isotonic conditions, resulting in the appearance of the basal chloride current, which plays an important role in the maintenance of basal cell volume in lymphoblastic leukemia cells. Chloride channels can be activated further to induce a regulatory volume recovery when cells are swollen.

Inhibition of the Sodium-Potassium-Chloride Cotransporter Isoform-1 reduces glioma invasion

Malignant gliomas metastasize throughout the brain by infiltrative cell migration into peritumoral areas. Invading cells undergo profound changes in cell shape and volume as they navigate extracellular spaces along blood vessels and white matter tracts. Volume changes are aided by the concerted release of osmotically active ions, most notably K(+) and Cl(-). Their efflux through ion channels along with obligated water causes rapid cell shrinkage. Suitable ionic gradients must be established and maintained through the activity of ion transport systems. Here, we show that the Sodium-Potassium-Chloride Cotransporter Isoform-1 (NKCC1) provides the major pathway for Cl(-) accumulation in glioma cells. NKCC1 localizes to the leading edge of invading processes, and pharmacologic inhibition using the loop diuretic bumetanide inhibits in vitro Transwell migration by 25% to 50%. Short hairpin RNA knockdowns of NKCC1 yielded a similar inhibition and a loss of bumetanide-sensitive cell volume regulation. A loss of NKCC1 function did not affect cell motility in two-dimensional assays lacking spatial constraints but manifested only when cells had to undergo volume changes during migration. Intracranial implantation of human gliomas into severe combined immunodeficient mice showed a marked reduction in cell invasion when NKCC1 function was disrupted genetically or by twice daily injection of the Food and Drug Administration-approved NKCC1 inhibitor Bumex. These data support the consideration of Bumex as adjuvant therapy for patients with high-grade gliomas.

Molecular interaction and functional regulation of ClC-3 by Ca2+/calmodulin-dependent protein kinase II (CaMKII) in human malignant glioma

Glioblastoma multiforme is the most common and lethal primary brain cancer in adults. Tumor cells diffusely infiltrate the brain making focal surgical and radiation treatment challenging. The invasion of glioma cells into normal brain is facilitated by the activity of ion channels aiding dynamic regulation of cell volume. Recent studies have specifically implicated ClC-3, a voltage-gated chloride channel, in this process. However, the interaction between ClC-3 activity and cell movement is poorly understood. Here, we demonstrate that ClC-3 is highly expressed on the plasma membrane of human glioma cells where its activity is regulated through phosphorylation via Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). Intracellular infusion of autoactivated CaMKII via patch pipette enhanced chloride currents 3-fold, and this regulation was inhibited by autocamtide-2 related inhibitory peptide, a CaMKII-specific inhibitor. CaMKII modulation of chloride currents was also lost upon stable small hairpin RNA knockdown of ClC-3 channels indicating a specific interaction of ClC-3 and CaMKII. In ClC-3-expressing cells, inhibition of CaMKII reduced glioma invasion to the same extent as direct inhibition of ClC-3. The importance of the molecular interaction of ClC-3 and CaMKII is further supported by our finding that CaMKII co-localizes and co-immunoprecipitates with ClC-3. ClC-3 and CaMKII also co-immunoprecipitate in tissue biopsies from patients diagnosed with grade IV glioblastoma. These tumor samples show 10-fold higher ClC-3 protein expression than nonmalignant brain. These data suggest that CaMKII is a molecular link translating intracellular calcium changes, which are intrinsically associated with glioma migration, to changes in ClC-3 conductance required for cell movement.