The ClC-3 chloride channel associated with microtubules is a target of paclitaxel in its induced-apoptosis

Epigenetic and transcriptomic alterations in the ClC-3-deficient mice consuming a normal diet

Introduction: Metabolic disorders are an important health concern that threatens life and burdens society severely. ClC-3 is a member of the chloride voltage-gated channel family, and ClC-3 deletion improved the phenotypes of dysglycemic metabolism and the impairment of insulin sensitivity. However, the effects of a healthy diet on transcriptome and epigenetics in ClC-3^-/- mice were not explained in detail. Methods: Here, we performed transcriptome sequencing and Reduced Representation Bisulfite Sequencing for the liver of 3 weeks old WT and ClC-3^-/- mice consuming a normal diet to insight into the epigenetic and transcriptomic alterations of ClC-3 deficient mice. Results: In the present study, we found that ClC-3^-/- mice that were younger than 8 weeks old had smaller bodies compared to ClC-3^+/+ mice with ad libitum self-feeding normal diet, and ClC-3^-/- mice that were older than 10 weeks old had a similar body weight. Except for the spleen, lung, and kidney, the average weight of the heart, liver, and brain in ClC-3^-/- mice was lower than that in ClC-3^+/+ mice. TG, TC, HDL, and LDL in fasting ClC-3^-/- mice were not significantly different from those in ClC-3^+/+ mice. Fasting blood glucose in ClC-3^-/- mice was lower than that in ClC-3^+/+ mice; the glucose tolerance test indicated the response to blood glucose increasing for ClC-3^-/- mice was torpid, but the efficiency of lowering blood glucose was much higher once started. Transcriptomic sequencing and reduced representation bisulfite sequencing for the liver of unweaned mice indicated that ClC-3 deletion significantly changed transcriptional expression and DNA methylation levels of glucose metabolism-related genes. A total of 92 genes were intersected between DEGs and DMRs-targeted genes, of which Nos3, Pik3r1, Socs1, and Acly were gathered in type II diabetes mellitus, insulin resistance, and metabolic pathways. Moreover, Pik3r1 and Acly expressions were obviously correlated with DNA methylation levels, not Nos3 and Socs1. However, the transcriptional levels of these four genes were not different between ClC-3^-/- and ClC-3^+/+ mice at the age of 12 weeks. Discussion: ClC-3 influenced the methylated modification to regulate glucose metabolism, of which the gene expressions could be driven to change again by a personalized diet-style intervention.

Excess iodide-induced reactive oxygen species elicit iodide efflux via β-tubulin-associated ClC-3 in thyrocytes

Iodide (I-) is crucial to thyroid function, and its regulation in thyrocytes involves ion transporters and reactive oxygen species (ROS). However, the extent of 2Cl-/H+ exchanger (ClC-3) involvement in the iodide (I-) efflux from thyrocytes remains unclear. Therefore, we examined the effects of ClC-3 on I- efflux. ClC-3 expression was found to significantly alter the serum TT3 and TT4 concentrations in mice. We further found that excess I- stimulation affected ClC-3 expression, distribution, and I- efflux in FRTL-5 cells. Immunofluorescence analyses indicated that ClC-3 mainly accumulated in the cell membrane and co-localized with β-tubulins after 24 h of excess I- treatment, and that this process depended on ROS production. Thus, ClC-3 may be involved in I- efflux at the apical pole of thyrocytes via excess I--induced ROS production and β-tubulin polymerization. Our results reveal novel insights into the role of ClC-3 in I- transport and thyroid function.

Ion channels as key partners of cytoskeleton in cancer disease

Several processes occur during tumor development including changes in cell morphology, a reorganization of the expression and distribution of the cytoskeleton proteins as well as ion channels. If cytoskeleton proteins and ion channels have been widely investigated in understanding cancer mechanisms, the interaction between these two elements and the identification of the associated signaling pathways are only beginning to emerge. In this review, we summarize the work published over the past 15 years relating to the roles played by ion channels in these mechanisms of reorganization of the cellular morphology, essential to metastatic dissemination, both through the physical interactions with elements of the cytoskeleton and by intracellular signaling pathways involved.

5‑Nitro‑2‑(3‑phenylpropylamino) benzoic acid induces apoptosis of human lens epithelial cells via reactive oxygen species and endoplasmic reticulum stress through the mitochondrial apoptosis pathway

Cataracts have a high incidence and prevalence rate worldwide, and they are the leading cause of blindness. Lens epithelial cell (LEC) apoptosis is often analysed in cataract research since it is the pathological basis of cataracts, except for congenital cataract. Chloride channels are present in ocular tissues, such as in trabecular cells, LECs and other cells. They serve an important role in apoptosis and participate in endoplasmic reticulum (ER) stress and oxidative stress. However, their role in the apoptosis of LECs has not been discussed. The present study examined the effects of the chloride channel blocker 5‑nitro‑2‑(3‑phenylpropylamino) benzoic acid (NPPB) in human LECs (HLECs) to elucidate the role of NPPB in HLECs and investigate the role and mechanism of chloride channels in cataract formation. HLECs were exposed to NPPB. Cell survival rate was evaluated using Cell Counting Kit‑8 assays. Oxidative stress was detected as reactive oxygen species (ROS) in cells by using a ROS assay kit. Apoptosis was examined by assessing mitochondrial membrane potential and using a JC‑1 assay kit, and western blot analysis was performed to measure the expression levels of mitochondrial‑dependent apoptosis pathway‑associated proteins. ER stress was evaluated by determining the intracellular calcium ion fluorescence intensity, and western blot analysis was performed to measure ER stress‑associated protein expression. The results revealed that NPPB treatment decreased the viability of HLECs and increased apoptosis. Additionally, NPPB increased intracellular ROS levels, as well as the number of JC‑1 monomers and the protein expression levels of B‑cell lymphoma‑2 (Bcl‑2)‑associated X and cleaved caspase‑3, and decreased Bcl‑2 protein expression. NPPB increased intracellular calcium ions, the protein expression levels of activating transcription factor 6, JNK, C/EBP homologous protein and caspase‑12, and the phosphorylation of protein kinase R‑like endoplasmic reticulum kinase. N‑acetylcysteine and 4‑phenylbutyric acid inhibited NPPB‑induced oxidative stress, ER stress and apoptosis. Therefore, NPPB treatment decreased cell viability and promoted apoptosis of HLECs via the promotion of oxidative and ER stress.

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.

MicroRNA-205-5p inhibits three-dimensional spheroid proliferation of ErbB2-overexpressing breast epithelial cells through direct targeting of CLCN3

We previously reported that microRNA-205-5p (miR-205-5p) is significantly decreased in the ErbB2-overexpressing breast epithelial cell line MCF10A-ErbB2 compared with control cells. In this study, we identified a direct target of miR-205-5p, chloride voltage-gated channel 3 (CLCN3). CLCN3 expression was induced by ErbB2 overexpression; this induced expression was then reduced to control levels by the transfection of the miR-205-5p precursor. In RNA-binding protein immunoprecipitation with Ago1/2/3 antibody, CLCN3 was significantly enriched in 293T embryonic kidney cells with miR-205-5p mimic transfection compared with negative control mimic transfection. In luciferase reporter assays using CLCN3 3'-UTR constructs, the miR-205-5p mimic significantly decreased reporter activity of both wild-type and partial mutant constructs in MCF10A-ErbB2 cells. In contrast, no inhibitory effects of the miR-205-5p mimic were detected using the complete mutant constructs. Since miR-205-5p expression in exosomes derived from MCF10A-neo cells was substantially higher than in exosomes derived from MCF10A-ErbB2 cells, we next investigated whether an exosome-mediated miR-205-5p transfer could control CLCN3 expression. To this end, exosomal miR-205-5p derived from MCF10A-neo cells was functionally transferred to MCF10A-ErbB2 cells, which served to decrease the expression of CLCN3. To assess the roles of CLCN3 in breast cancer, we next performed three-dimensional (3D) spheroid proliferation analyses using MCF10A-ErbB2 cells treated with MCF10A-neo-derived exosomes or CLCN3 shRNA stably expressing SKBR3 and MDA-MB-453 breast cancer cells. Our results showed that both treatment with MCF10A-neo-derived exosome and CLCN3 shRNA expression suppressed 3D spheroid proliferation. Collectively, these novel findings suggest that CLCN3 may be a novel direct target of miR-205-5p and this CLCN3/miR-205-5p interaction may serve a pivotal role in regulating breast cancer cellular proliferation under physiological conditions.

The inhibition of chloride intracellular channel 1 enhances Ca2+ and reactive oxygen species signaling in A549 human lung cancer cells

Chloride intracellular channel 1 (CLIC1) is a promising therapeutic target in cancer due to its intrinsic characteristics; it is overexpressed in specific tumor types and its localization changes from cytosolic to surface membrane depending on activities and cell cycle progression. Ca²⁺ and reactive oxygen species (ROS) are critical signaling molecules that modulate diverse cellular functions, including cell death. In this study, we investigated the function of CLIC1 in Ca²⁺ and ROS signaling in A549 human lung cancer cells. Depletion of CLIC1 via shRNAs in A549 cells increased DNA double-strand breaks both under control conditions and under treatment with the putative anticancer agent chelerythrine, accompanied by a concomitant increase in the p-JNK level. CLIC1 knockdown greatly increased basal ROS levels, an effect prevented by BAPTA-AM, an intracellular calcium chelator. Intracellular Ca²⁺ measurements clearly showed that CLIC1 knockdown significantly increased chelerythrine-induced Ca²⁺ signaling as well as the basal Ca²⁺ level in A549 cells compared to these levels in control cells. Suppression of extracellular Ca²⁺ restored the basal Ca²⁺ level in CLIC1-knockdown A549 cells relative to that in control cells, implying that CLIC1 regulates [Ca²⁺]_i through Ca²⁺ entry across the plasma membrane. Consistent with this finding, the L-type Ca²⁺ channel (LTCC) blocker nifedipine reduced the basal Ca²⁺ level in CLIC1 knockdown cells to that in control cells. Taken together, our results demonstrate that CLIC1 knockdown induces an increase in the intracellular Ca²⁺ level via LTCC, which then triggers excessive ROS production and consequent JNK activation. Thus, CLIC1 is a key regulator of Ca²⁺ signaling in the control of cancer cell survival.

Overexpression of ClC-3 Chloride Channel in Chondrosarcoma: An In Vivo Immunohistochemical Study with Tissue Microarray

Background

Recently, ClC-3 chloride channel expression has been noted to be high in some tumors. In chondrosarcoma, which is a malignant tumor with a high incidence in the bone, there has been no previous literature regarding ClC-3 chloride channel expression. Here we evaluated the expression of ClC-3 chloride channel in chondrosarcoma and explored its clinical significance.

Material/Methods

In this study, 75 chondrosarcoma and 5 normal cartilage tissues were collected. Thereafter, tissue microarray was performed. Immunohistochemistry was also used to observe the level of ClC-3 chloride channel expression between normal and chondrosarcoma tissues.

Results

Results showed that the expression of ClC-3 chloride channel in the normal chondrocyte was thinner, since it showed distinct differentiation among chondrosarcoma specimens. Interestingly, we noticed that the moderately-differentiated chondrosarcoma (MDC) and the poorly-differentiated chondrosarcoma (PDC) exhibited 94.44% of ClC-3 chloride channel. Besides, the subcellular localization of ClC-3 chloride channel was changed in association with malignant degree changes. The subcellular localization of ClC-3 chloride channel in the MDC and PDC tissue was localized in the cytoplasm and both nucleus and cytoplasm: 83.33% (5 out of 6 cases) and 91.66% (11 out of 12 cases) respectively. On the other hand, we noticed that patient age and gender could have a relation with ClC-3 chloride channel expression; 30- to 60-year-old males showed more expression.

Conclusions

These results demonstrated a high frequency of ClC-3 chloride channel overexpression and subcellular localization differences in MDC and PDC tissue, suggesting a specific role of ClC-3 chloride channel in the pathogenesis of chondrosarcoma.

bFGF overexpression adipose derived mesenchymal stem cells improved the survival of pulmonary arterial endothelial cells via PI3k/Akt signaling pathway

Pulmonary arterial hypertension (PAH) is characterized as pulmonary arterial endothelial dysfunction and endothelial cells over proliferation, therefore, the repair of pulmonary arterial endothelial cells has been a common goal in treating PAH. In the present study, human adipose derived mesenchymal stem cells (ASCs) were transfected with bFGF lentiviral vector and co-cultured with monocrotaline pyrrole treated human pulmonary arterial endothelial cells (HPAECs). The results showed that bFGF-ASCs improved the proliferation, viability and decreased the apoptosis of HPAECs, besides, improved PAH was observed in PAH rat models. Western blot analysis showed that the PI3k and p-Akt protein expression level increased in HPAECs, suggesting the activation of the PI3k/Akt signaling pathway. With the administration of LY294002, the bFGF induced HPAECs survival and PI3k/Akt signaling activation were successfully blocked. The present study demonstrated that bFGF transfected ASCs improved the survival of HPAECs by activating the PI3k/Akt pathway.

Chloride channel-3 mediates multidrug resistance of cancer by upregulating P-glycoprotein expression

Chloride channel-3 (ClC-3), a member of the ClC family of voltage-gated Cl^- channels, is involved in the resistance of tumor cells to chemotherapeutic drugs. Here, we report a new mechanism for ClC-3 in mediating multidrug resistance (MDR). ClC-3 was highly expressed in the P-glycoprotein (P-gp)-dependent human lung adenocarcinoma cell line (A549)/paclitaxel (PTX) and the human breast carcinoma cell line (MCF-7)/doxorubicin (DOX) resistant cells. Changes in the ClC-3 expression resulted in the development of drug resistance in formerly drug-sensitive A549 or MCF-7 cells, and drug sensitivity in formerly drug-resistant A549/Taxol and MCF-7/DOX cells. Double transgenic MMTV-PyMT/CLCN3 mice with spontaneous mammary cancer and ClC-3 overexpression demonstrated drug resistance to PTX and DOX. ClC-3 expression upregulated the expression of MDR1 messenger RNA and P-gp by activating the nuclear factor-κB (NF-κB)-signaling pathway. These data suggest that ClC-3 expression in cancer cells induces MDR by upregulating NF-κB-signaling-dependent P-gp expression involving another new mechanism for ClC-3 in the development of drug resistance of cancers.

Opening of the CLC-3 chloride channel induced by dihydroartemisinin contributed to early apoptotic events in human poorly differentiated nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a specific type of head and neck cancer that is prevalent in Southeast Asia. Dihydroartemisinin (DHA), a semisynthetic derivative of artemisinin, has specific anticancer activity. Here, we aimed to investigate the role of the CLC-3 chloride channel in the anticancer effect of DHA in poorly differentiated NPC CNE-2Z cells. First, we observed that DHA could specifically inhibit the proliferation, induce apoptosis, and increase cleaved caspase-3 expression in the CNE-2Z cells. Then, we found that DHA could activate chloride channels, which led to Cl^- efflux and apoptotic volume decrease (AVD) in the early stage in the CNE-2Z cells. DHA also specifically increased CLC-3 chloride channel protein expression in the CNE-2Z cells. Silencing of the CLC-3 protein expression depleted the Cl^- currents, and decreased the AVD capacity and cell apoptosis induced by DHA. Finally, we revealed that the [Ca²⁺ ]_i increased after around 6 hours of treatment with DHA, which was also inhibited by silencing of the CLC-3 protein expression. Our data demonstrated that the selective antitumor activities of DHA in NPC may occur through the specific activation of the CLC-3 Cl^- channel, leading to Cl^- efflux, and induced AVD, then led to [Ca²⁺ ]_i accumulation and caspase-3 activation, and finally induced apoptosis. The activation of the CLC-3 chloride channel played an essential and proximal upstream role in the antitumor activities of DHA.

High expression of leucine‑rich repeat‑containing 8A is indicative of a worse outcome of colon cancer patients by enhancing cancer cell growth and metastasis

To survive, cells need to avoid excessive volume change that jeopardizes structural integrity and stability of the intracellular milieu. Searching for the molecular identity of volume‑regulated anion channel (VRAC) has yielded multiple potential candidates, but none has been confirmed. Recently, it is reported that leucine‑rich repeat‑containing 8A (LRRC8A) is a main molecular determinant of VRAC current. The biological functions of LRRC8 family proteins are poorly understood, particularly in cancer. In the present study, we investigated LRRC8A in the most common cancers of the digestive system. LRRC8A proteins were found to be abundantly expressed in the esophagus, stomach, duodenum, colon, rectum, liver and pancreas. LRRC8A was elevated in 60% of colorectal cancer patient tissues, which was higher than that in patients with cancer of the esophagus, stomach, duodenum, liver and pancreas. Colon cancer patients with high‑ expressed LRRC8A had a survival time of 54.9±5.5 months, shorter than that of patients with low‑expressed LRRC8A (77.1±3.7). Moreover, survival time (52.6±7.3 months) of patients with metastases in the lymph nodes was shorter than that of patients without positive lymph nodes (72.2±3.6); patients with positive lymph nodes and an elevated LRRC8A expression had the highest mortality rate (~80%). These rates were not observed in rectal cancer. After LRRC8A protein was knocked down in colon cancer HCT116 cells, VRAC currents, migration and tumorigenesis in nude mice were significantly inhibited. In conclusion, we propose that LRRC8A could be a novel prognostic biomarker for colon cancer patient survival, and that the elevated expression of LRRC8A may enhance cancer cell growth and metastasis, and worsen the outcome of patients.

The apoptotic effect of Zoledronic acid on the nasopharyngeal carcinoma cells via ROS mediated chloride channel activation

Zoledronic acid (ZA), a third-generation bisphosphonate, has been applied for treatment of bone metastases caused by malignant tumors. Recent studies have found its anti-cancer effects on various tumor cells. One of the mechanisms of anti-cancer effects of ZA is induction of apoptosis. However, the mechanisms of ZA-induced apoptosis in tumor cells have not been clarified clearly. In this study, we investigated the roles of chloride channels in ZA-induced apoptosis in nasopharyngeal carcinoma CNE-2Z cells. Apoptosis and chloride current were induced by ZA and suppressed by chloride channel blockers. After the knockdown of ClC-3 expression by ClC-3 siRNA, ZA-induced chloride current and apoptosis were significantly suppressed, indicating that the chloride channel participated in ZA-induced apoptosis may be ClC-3. When reactive oxygen species (ROS) generation was inhibited by the antioxidant N-acetyl-L-cysteine (L-NAC), ZA-induced apoptosis and chloride current were blocked accordingly, suggesting that ZA induces apoptosis through promoting ROS production and subsequently activating chloride channel.

A new clerodane furano diterpene glycoside from Tinospora cordifolia triggers autophagy and apoptosis in HCT-116 colon cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Tinospora cordifolia is a miraculous ayurvedic herb used in the treatment of innumerable diseases such as diabetes, gonorrhea, secondary syphilis, anaemia, rheumatoid arthritis, dermatological diseases, cancer, gout, jaundice, asthma, leprosy, in the treatment of bone fractures, liver & intestinal disorders, purifies the blood, gives new life to the whole body; (rejuvenating herb) and many more. Recent studies have revealed the anticancer potential of this plant but not much work has been done on the anticancer chemical constituents actually responsible for its amazing anticancer effects. This prompted us to investigate this plant further for new potent anticancer molecules.

AIM OF THE STUDY

The present study was designed to isolate and identify new promising anticancer candidates from the aqueous alcoholic extract of T. cordifolia using bioassay-guided fractionation.

MATERIALS AND METHODS

The structures of the isolated compounds were determined on the basis of spectroscopic data interpretation and that of new potent anticancer molecule, TC-2 was confirmed by a single-crystal X-ray crystallographic analysis of its corresponding acetate. The in vitro anti-cancer activity of TC-2 was evaluated by SRB assay and the autophagic activity was investigated by immunofluorescence microscopy. Annexin-V FITC and PI dual staining was applied for the detection of apoptosis. The studies on Mitochondrial Membrane potential and ROS (Reactive oxygen species) production were also done.

RESULTS

Bioassay guided fractionation and purification of the aqueous alcoholic stem extract of Tinospora cordifolia led to the isolation of a new clerodane furano diterpene glycoside (TC-2) along with five known compounds i.e. cordifolioside A (β-D-Glucopyranoside,4-(3-hydroxy-1-propenyl)- 2,6-dimethoxyphenyl 3-O-D-apio-β-D-furanosyl) (TC-1), β-Sitosterol(TC-3), 2β,3β:15,16-Diepoxy- 4α, 6β-dihydroxy-13(16),14-clerodadiene-17,12:18,1-diolide (TC-4), ecdysterone(TC-5) and tinosporoside(TC-6). TC-2 emerged as a potential candidate for the treatment of colon cancer.

CONCLUSION

The overall study on the bioassay guided isolation of T.cordifolia identified and isolated a new clerodane furano diterpenoid that exhibited anticancer activity via induction of mitochondria mediated apoptosis and autophagy in HCT116 cells. We have reported a promising future candidate for treating colon cancer.

NPPB modulates apoptosis, proliferation, migration and extracellular matrix synthesis of conjunctival fibroblasts by inhibiting PI3K/AKT signaling

When treating glaucoma, excessive scar tissue reactions reduce the postoperative survival rate of the filtering bleb. Accumulating evidence has demonstrated that the proliferation, migration and extracellular matrix (ECM) synthesis of fibroblasts are important molecular mechanisms underlying scar formation. Recent evidence has demonstrated that chloride channels play an important role in controlling cell proliferation, apoptosis, migration and the cell cycle process in several cell types, but the effects of chloride channels on conjunctival fibroblasts have not be studied. The aim of the present study was to investigate the effects of the chloride channel blocker 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) on cell proliferation, apoptosis, migration, cell cycle progression and ECM synthesis in human conjunctival fibroblasts (HConFs), and to further investigate the mechanism of resistance to scar formation following glaucoma filtration surgery. HConFs were exposed to NPPB or lubiprostone. Cell proliferation and viability was evaluated using the Cell Counting Kit-8. Cell migration was measured using Transwell migration and scratch‑wound assays. Flow cytometry was used to study apoptosis and cell cycle progression. Quantitative polymerase chain reaction and western blot analyses were performed to determine mRNA and protein expression levels, respectively. Following NPPB treatment, HConFs exhibited reduced proliferation and migration, along with increased apoptosis. NPPB also inhibited cell cycle progression by arresting cells in the G0̸G1 phase and reducing collagen I and fibronectin expression, as well as the phosphorylation of phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT). However, lubiprostone treatment exerted the opposite effects on HConFs. Therefore, NPPB treatment inhibited proliferation, migration, cell cycle progression and synthesis of the ECM, while promoting apoptosis in HConFs, by inhibiting the PI3K̸AKT signaling pathway.

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.

The selective cytotoxicity of DSF-Cu attributes to the biomechanical properties and cytoskeleton rearrangements in the normal and cancerous nasopharyngeal epithelial cells

Cancer initiation and progression follow complex changes of cellular architecture and biomechanical property. Cancer cells with more submissive (or "softer") than their healthy counterparts attributed to the reorganization of the complex cytoskeleton structure, may be considered as a potential anti-tumor therapeutic target. In this study, atomic force microscopy (AFM) was carried out to detect the topographical and biophysical changes of nasopharyngeal carcinoma CNE-2Z cells and normal nasopharyngeal epithelial cells NP69-SV40T by treating the Disulfiram chelated with Cu²⁺ (DSF-Cu). DSF-Cu induced the apoptotic population, ROS production and decreased the NF-κB-p65 expression of CNE-2Z cells, which was much higher than those of NP69-SV40T cells. DSF-Cu caused the obvious changes of cell morphology and membrane ultrastructure in CNE-2Z cells. The roughness decreased and stiffness increased significantly in CNE-2Z cells, which correlated with the rearrangement of intracellular F-actin, FLNa and α-tubulin structures in CNE-2Z cells. And the adhesion force of CNE-2Z cells was also increased accompanied with the increased E-cadherin expression. However, these results could not be observed in the NP69-SV40T cells even the concentration of DSF reached up to 400nM. Finally, the detection of cell wound scratch assay confirmed DSF-Cu could inhibit the migration of CNE-2Z cells, but no effect on NP69-SV40T cells. These findings demonstrated the selective cytotoxicity of DSF-Cu in CNE-2Z cells may attribute to the different mechanical properties and cytoskeleton rearrangement from the normal nasopharyngeal epithelial cells.

A novel colchicine-based microtubule inhibitor exhibits potent antitumor activity by inducing mitochondrial mediated apoptosis in MIA PaCa-2 pancreatic cancer cells

Colchicine, an antimitotic alkaloid isolated from Colchicum autumnale, is a classical drug for treatment of gout and familial Mediterranean fever. It causes antiproliferative effects through the inhibition of microtubule formation, which leads to mitotic arrest and cell death by apoptosis. Here, we report that a novel colchicine analog, 4o (N-[(7S)-1,2,3-trimethoxy-9-oxo-10-[3-(trifluoromethyl)-4-chlorophenylamino]-5,6,7,9-tetrahydrobenzo[a]heptalen-7-yl]acetamide), which exhibited potent anticancer activities both in vitro and in vivo. In this study, 4o with excellent pharmacokinetic profile and no P-gp induction liability displayed strong inhibition of proliferation against various human cancer cell lines. However, pancreatic cancer cell line MIA PaCa-2 was found to be more sensitive towards 4o and showed strong inhibition in concentration and time-dependent manner. By increasing intracellular reactive oxygen species (ROS) levels, 4o induced endoplasmic reticular stress and mitochondrial dysfunction in MIA PaCa-2 cells. Blockage of ROS production reversed 4o-induced endoplasmic reticulum (ER) stress, calcium release, and cell death. More importantly, it revealed that increased ROS generation might be an effective strategy in treating human pancreatic cancer. Further 4o treatment induced mitotic arrest, altered the expression of cell cycle-associated proteins, and disrupted the microtubules in MIA PaCa-2 cells. 4o treatment caused loss of mitochondrial membrane potential, cytochrome c release, upregulation of Bax, downregulation of Bcl-2, and cleavage of caspase-3, thereby showing activation of mitochondrial mediated apoptosis. The in vivo anticancer activity of the compound was studied using sarcoma-180 (ascitic) and leukemia (P388 lymphocytic and L1210 lymphoid) models in mice and showed promising antitumor activity with the least toxicity unlike colchicine. Such studies have hitherto not been reported. Taken together, these findings highlighted that 4o, a potent derivative of colchicine, causes tumor regression with reduced toxicity and provides a novel anticancer candidate for the therapeutic use.

Potent effects of dioscin against gastric cancer in vitro and in vivo

BACKGROUND

We previously reported the effect of dioscin on human gastric carcinoma SGC-7901 cells, but its effects on other gastric cancers are still unknown.

PURPOSE

The present paper aimed to demonstrate the activity of dioscin against human gastric carcinoma MGC-803 and MKN-45.

STUDY DESIGN

In our study, MGC-803 and MKN-45 cells were used to examine the effects of dioscin on human gastric carcinoma in vitro. The effects of dioscin against human gastric carcinoma in vivo were accomplished by the xenografts of MGC-803 cells in BALB/c nude mice.

METHODS

AO/EB and DAPI staining, TEM, single cell gel electrophoresis and flow cytometry assays were used in cell experiments. Then, an iTRAQ-based proteomics approach, DNA and siRNA transfection experiments were carried out for mechanism investigation.

RESULTS

In MGC-803 cells, dioscin caused DNA damage and mitochondrial change, induced ROS generation, Ca(2+) release and cell apoptosis, and blocked cell cycle at S phase. In vivo results showed that dioscin significantly suppressed the tumor growth of MGC-803 cell xenografts in nude mice. In addition, dioscin markedly inhibited cell migration, caused Cytochrome c release and adjusted mitochondrial signal pathway. Then, an iTRAQ-based proteomics approach was carried out and 121 differentially expressed proteins were found, in which five biomarkers associated with cell cycle, apoptosis and migration were evaluated. Dioscin significantly up-regulated the levels of GALR-2 and RBM-3, and down-regulated CAP-1, Tribbles-2 and CliC-3. Furthermore, overexpressed DNA transfection of CAP-1 enhanced cell migration and invasion, which was decreased by dioscin. SiRNA to Tribbles-2 affected the protein levels of Bcl-2, Bax and MAPKs, suggesting that dioscin decreased Tribbles-2 level leading to cell apoptosis.

CONCLUSION

Our works confirmed the activity of dioscin against gastric cancer. In addition, this work also provided that dioscin is a new potent candidate for treating gastric cancer in the future.

Fluid shear stress enhances the cell volume decrease of osteoblast cells by increasing the expression of the ClC-3 chloride channel

ClC-3 is a volume-sensitive chloride channel that is responsible for cell volume adjustment and regulatory cell volume decrease (RVD). In order to evaluate the effects of fluid shear stress (FSS) stimulation on the osteoblast ClC-3 chloride channel, MC3T3-E1 cells were stimulated by FSS in the experimental group. Fluorescence quantitative polymerase chain reaction was used to detect changes in ClC-3 mRNA expression, the chloride ion fluorescent probe N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE) was used to detect the chloride channel activity, and whole-cell patch clamping was used to monitor the changes in the volume-sensitive chloride current activated by a hypotonic environment following mechanical stimulation. The results show that the expression of the osteoblast chloride channel ClC-3 was significantly higher in the FSS group compared with the control group. MQAE fluorescence intensity was significantly reduced in the FSS group compared to the control group, suggesting that mechanical stimulation increased chloride channel activity and increased the efflux of intracellular chloride ions. Image analysis of osteoblast volume changes showed that osteoblast RVD was enhanced by mechanical stimulation. Whole-cell patch clamping showed that the osteoblast volume-sensitive chloride current was larger in the stimulated group compared to the control group, suggesting that elevated ClC-3 chloride channel expression results in an increased volume-sensitive chloride current. In conclusion, FSS stimulation enhances the RVD of osteoblast cell by increasing the expression of the ClC-3 and enhancing the chloride channel activity.

The AQP-3 water channel is a pivotal modulator of glycerol-induced chloride channel activation in nasopharyngeal carcinoma cells

Aquaporin (AQP) and chloride channels are ubiquitous in virtually all living cells, playing pivotal roles in cell proliferation, migration and apoptosis. We previously reported that AQP-3 aquaglyceroporin and ClC-3 chloride channels could form complexes to regulate cell volume in nasopharyngeal carcinoma cells. In this study, the roles of AQP-3 in their hetero-complexes were further investigated. Glycerol entered the cells via AQP-3 and induced two different Cl(-) currents through cell swelling-dependent or -independent pathways. The swelling-dependent Cl(-) current was significantly inhibited by pretreatment with CuCl2 and AQP-3-siRNA. After siRNA-induced AQP-3 knock-down, the 140 mM glycerol isoosmotic solution swelled cells by 22% (45% in AQP-3-intact cells) and induced a smaller Cl(-) current; this current was smaller than that activated by 8% cell volume swelling, which induced by the 140 mM glycerol hyperosmotic solution in AQP-3-intact cells. This suggests that the interaction between AQP-3 and ClC-3 plays an important role in cell volume regulation and that AQP-3 may be a modulator that opens volume-regulated chloride channels. The swelling-independent Cl(-) current, which was activated by extracellular glycerol, was reduced by CuCl2 and AQP-3-siRNA pretreatment. Dialyzing glycerol into cells via the pipette directly induced the swelling-independent Cl(-) current; however this current was blocked by AQP-3 down-regulation, suggesting AQP-3 is essential for the opening of chloride channels. In conclusion, AQP-3 is the pathway for water, glycerol and other small solutes to enter cells, and it may be an essential modulator for the gating of chloride channels.

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.

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."

CLC-3 channels in cancer (review)

Ion channels are involved in regulating cell proliferation and apoptosis (programed cell death). Since increased cellular proliferation and inhibition of apoptosis are characteristic features of tumorigenesis, targeting ion channels is a promising strategy for treating cancer. CLC-3 is a member of the voltage-gated chloride channel superfamily and is expressed in many cancer cells. In the plasma membrane, CLC-3 functions as a chloride channel and is associated with cell proliferation and apoptosis. CLC-3 is also located in intracellular compartments, contributing to their acidity, which increases sequestration of drugs and leads to chemotherapy drug resistance. In this review, we summarize the recent findings concerning the involvement of CLC-3 in cancer and explore its potential in cancer therapy.

B-9-3, a novel β-carboline derivative exhibits anti-cancer activity via induction of apoptosis and inhibition of cell migration in vitro

Peganum harmala L is an important medicinal plant that has been used from ancient time due to its alkaloids rich of ß-carbolines. Harmane is a naturally occurring ß-carboline extracted from Peganum harmala L, that exhibits a wide range of biological, psychopharmacological, and toxicological actions. The synthesis of novel derivatives with high anti-cancer activity and less side effects is necessary. In the present study, B-9-3-a semi-synthetic compound that is formed of two harmane molecules bound by a butyl group-showed a strong anti-cancer activity against a human lung cancer cell line, a human breast cancer cell line, and a human colorectal carcinoma cell line. B-9-3 anti-proliferative effect followed a similar pattern in the three cell lines. This pattern includes a dose-dependent induction of apoptosis, or necroptosis as confirmed by Hoechst staining, flow cytometry and western blot analyses, and the inhibition of cancer cells migration that was shown to be dependent on the drug׳s concentration as well. Moreover, B-9-3 inhibited tube formation in human umbilical vascular endothelial cell line (HUVEC), which indicates an anti-angiogenesis activity in vitro. In summary, B-9-3, a semi-synthetic derivative of ß-carboline, has an anti-proliferative effect against tumor cells via induction of apoptosis and inhibition of cell migration.