Nuclear localisation sequences of chloride intracellular channels 1 and 4 facilitate nuclear import via interactions with import mediator importin-α: An empirical and theoretical perspective.

Chloride intracellular channel proteins (CLICs) display ubiquitous expression, with each member exhibiting specific subcellular localisation. While all CLICs, except CLIC3, exhibit a highly conserved putative nuclear localisation sequence (NLS), only CLIC1, CLIC3 and CLIC4 exist within the nucleus. The CLIC4 NLS, 199-KVVAKKYR-206, appears crucial for nuclear entry and interacts with mouse nuclear import mediator Impα isoform 1, omitting the IBB domain (mImpα1ΔIBB). The essential nature of the basic residues in the CLIC4 NLS has been established by the fact that mutating out these residues inhibits nuclear import, which in turn is linked to cutaneous squamous cell cancer. Given the conservation of the CLIC NLS, CLIC1 likely follows a similar import pathway to CLIC4. Peptides of the CLIC1 (Pep1; Pep1_S C/S mutant) and CLIC4 (Pep4) NLSs were designed to examine binding to human Impα isoform 1, omitting the IBB domain (hImpα1ΔIBB). Molecular docking indicated that the core CLIC NLS region (KKYR) forms a similar binding pattern to both mImpα1ΔIBB and hImpα1ΔIBB. Fluorescence quenching demonstrated that Pep1_S (Kd ≈ 237 µM) and Pep4 (Kd ≈ 317 µM) bind hImpα1ΔIBB weakly. Isothermal titration calorimetry confirmed the weak binding interaction between Pep4 and hImpα1ΔIBB (Kd ≈ 130 µM) and the presence of a proton-linked effect. This weak interaction may be due to regions distal from the CLIC NLS needed to stabilise and strengthen hImpα1ΔIBB binding. Additionally, this NLS may preferentially bind another hImpα isoform with different flexibility properties.

Comparative kinetic analysis of ascorbate (Vitamin-C) recycling dehydroascorbate reductases from plants and humans.

Ascorbate is an important cellular antioxidant that gets readily oxidized to dehydroascorbate (DHA). Recycling of DHA is therefore paramount in the maintenance of cellular homeostasis and preventing oxidative stress. Dehydroascorbate reductases (DHARs), in conjunction with glutathione (GSH), carry out this vital process in eukaryotes, among which plant DHARs have garnered considerable attention. A detailed kinetic analysis of plant DHARs relative to their human counterparts is, however, lacking. Chloride intracellular channels (HsCLICs) are close homologs of plant DHARs, recently demonstrated to share their enzymatic activity. This study reports the highest turnover rate for a plant DHAR from stress adapted Pennisetum glaucum (PgDHAR). In comparison, HsCLICs 1, 3, and 4 reduced DHA at a significantly lower rate. We further show that the catalytic cysteine from both homologs was susceptible to varying degrees of oxidation, validated by crystal structures and mass-spectrometry. Our findings may have broader implications on crop improvement using pearl millet DHAR vis-à-vis discovery of cancer therapeutics targeting Vitamin-C recycling capability of human CLICs.

CLIC1 Protein Accumulates in Circulating Monocyte Membrane during Neurodegeneration.

Pathologies that lead to neurodegeneration in the central nervous system (CNS) represent a major contemporary medical challenge. Neurodegenerative processes, like those that occur in Alzheimer's disease (AD) are progressive, and at the moment, they are unstoppable. Not only is an adequate therapy missing but diagnosis is also extremely complicated. The most reliable method is the measurement of beta amyloid and tau peptides concentration in the cerebrospinal fluid (CSF). However, collecting liquid samples from the CNS is an invasive procedure, thus it is not suitable for a large-scale prevention program. Ideally, blood testing is the most manageable and appropriate diagnostic procedure for a massive population screening. Recently, a few candidates, including proteins or microRNAs present in plasma/serum have been identified. The aim of the present work is to propose the chloride intracellular channel 1 (CLIC1) protein as a potential marker of neurodegenerative processes. CLIC1 protein accumulates in peripheral blood mononuclear cells (PBMCs), and increases drastically when the CNS is in a chronic inflammatory state. In AD patients, both immunolocalization and mRNA quantification are able to show the behavior of CLIC1 during a persistent inflammatory state of the CNS. In particular, confocal microscopy analysis and electrophysiological measurements highlight the significant presence of transmembrane CLIC1 (tmCLIC1) in PBMCs from AD patients. Recent investigations suggest that tmCLIC1 has a very specific role. This provides an opportunity to use blood tests and conventional technologies to discriminate between healthy individuals and patients with ongoing neurodegenerative processes.

Exosome-mediated transfer of CLIC1 contributes to the vincristine-resistance in gastric cancer.

Our previous study shows that high Chloride intracellular channel 1 (CLIC1) expression can efficiently enhance invasion and migration of gastric cancer (GC) cells in vitro. Growing evidences have found that exosomes are involved in chemotherapy resistance in several cancers including GC. We aimed to evaluate the effect of the exosome-mediated transfer of CLIC1 in the vincristine-resistance of GC. The effect of exosome-mediated transfer of CLIC1 on the development of resistance to vincristine in GC cell line SGC-7901 and the potential underlying mechanisms were investigated by Cell Counting Kit-8 (CCK8), RT-PCR, and Western blotting. Exosomes were isolated from cell supernatants by differential ultracentrifugation. Comparing with SGC-7901, the expression level of CLIC1 is higher in vincristine­resistant cell line SGC-7901/VCR (P < 0.05). After silencing the expression of CLIC1 by RNA interference, the half inhibition concentration (IC50) to vincristine decreased significantly in SGC-7901/VCR, and the expression of CLIC1 decreased significantly in exosomes from SGC-7901/VCR. After 48 h co-culturing with exosomes from SGC-7901/VCR, the IC50 to vincristine in SGC-7901 increased significantly, and the expression of CLIC1, P-gp, and Bcl-2 were significantly up-regulated. CLIC1 was closely associated with the resistance to vincristine in GC, and exosome-mediated transfer of CLIC1 could induce the development of resistance to vincristine in vitro. The possible mechanism was related to up-regulated P-gp and Bcl-2. However, in vivo study was needed to confirm the results in future.

Effect of CLIC1 gene silencing on proliferation, migration, invasion and apoptosis of human gallbladder cancer cells.

This study aimed to explore the effects of CLIC1 gene silencing on proliferation, migration, invasion and apoptosis of human gallbladder cancer (GBC). GBC and normal gallbladder tissues were extracted for the detection of mRNA and protein expressions of CLIC1. GBC-SD and NOZ cells in the logarithmic growth phase were selected to conduct the experiment. Three different siRNA recombined expression vectors were established using CLIC1 as a target at different sites. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blotting were, respectively, used to detect the CLIC1 mRNA and protein expressions. MTT assay was performed to detect the cell proliferation. Flow cytometry was applied to measure the cell apoptosis and cell cycle distribution. The variations of cell migration and invasion were evaluated using Transwell assay. GBC tissues showed higher CLIC1 mRNA and protein expressions than normal gallbladder tissues. The CLIC1 mRNA and protein expressions in the CLIC1 siRNA group were significantly lower than those in the NC and blank groups. Compared with the NC and blank groups, the CLIC1 siRNA group showed a significant decrease in cell proliferation but an obvious increase in apoptosis rate in GBC cells. Besides, in the CLIC1 siRNA group, cell percentage in G0/G1 and G2/M phase was gradually increased but decreased in S phases. The migration and invasion abilities in GBC cells were significantly lower than those in the NC and blank groups. Our study demonstrates that CLIC1 gene silencing could promote apoptosis and inhibit proliferation migration and invasion of GBC cells.

The intracellular chloride channel proteins CLIC1 and CLIC4 induce IL-1ß transcription and activate the NLRP3 inflammasome.

The NLRP3 inflammasome is a multiprotein complex that regulates the activation of caspase-1 leading to the maturation of the proinflammatory cytokines IL-1ß and IL-18 and promoting pyroptosis. Classically, the NLRP3 inflammasome in murine macrophages is activated by the recognition of pathogen-associated molecular patterns and by many structurally unrelated factors. Understanding the precise mechanism of NLRP3 activation by such a wide array of stimuli remains elusive, but several signaling events, including cytosolic efflux and influx of select ions, have been suggested. Accordingly, several studies have indicated a role of anion channels in NLRP3 inflammasome assembly, but their direct involvement has not been shown. Here, we report that the chloride intracellular channel proteins CLIC1 and CLIC4 participate in the regulation of the NLRP3 inflammasome. Confocal microscopy and cell fractionation experiments revealed that upon LPS stimulation of macrophages, CLIC1 and CLIC4 translocated into the nucleus and cellular membrane. In LPS/ATP-stimulated bone marrow-derived macrophages (BMDMs), CLIC1 or CLIC4 siRNA transfection impaired transcription of IL-1ß, ASC speck formation, and secretion of mature IL-1ß. Collectively, our results demonstrate that CLIC1 and CLIC4 participate both in the priming signal for IL-1ß and in NLRP3 activation.

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."

CLIC1 functional expression is required for cAMP-induced neurite elongation in post-natal mouse retinal ganglion cells.

During neuronal differentiation, axonal elongation is regulated by both external and intrinsic stimuli, including neurotropic factors, cytoskeleton dynamics, second messengers such as cyclic adenosine monophosphate (cAMP), and neuronal excitability. Chloride intracellular channel 1 (CLIC1) is a cytoplasmic hydrophilic protein that, upon stimulation, dimerizes and translocates to the plasma membrane, where it contributes to increase the membrane chloride conductance. Here, we investigated the expression of CLIC1 in primary hippocampal neurons and retinal ganglion cells (RGCs) and examined how the functional expression of CLIC1 specifically modulates neurite outgrowth of neonatal murine RGCs. Using a combination of electrophysiology and immunohistochemistry, we found that CLIC1 is expressed in hippocampal neurons and RGCs and that the chloride current mediated by CLIC1 is required for maintaining growth cone morphology and sustaining cAMP-stimulated neurite elongation in dissociated immunopurified RGCs. In cultured RGCs, inhibition of CLIC1 ionic current through the pharmacological blocker IAA94 or a specific anti-CLIC1 antibody directed against its extracellular domain prevents the neurite outgrowth induced by cAMP. CLIC1-mediated chloride current, which results from an increased open probability of the channel, is detected only when cAMP is elevated. Inhibition of protein kinase A prevents such current. These results indicate that CLIC1 functional expression is regulated by cAMP via protein kinase A and is required for neurite outgrowth modulation during neuronal differentiation. Using a combination of electrophysiology and immunohistochemistry, we found that the chloride intracellular channel 1 (CLIC1) protein modulates the speed of neurite growth. The chloride current mediated by CLIC1 is essential for maintaining growth cone morphology and is required for sustaining cAMP-stimulated neurite elongation in dissociated immunopurified neurons. The presence of either the CLIC1 current blocker IAA94 or the anti-CLIC1 antibody inhibits neurite growth of Retina Ganglion Cells cultured in the presence of 10 micromolar forskolin for 24 h.

Chloride Intracellular Channel Protein 1 (CLIC1) Is a Critical Host Cellular Factor for Influenza A Virus Replication.

(1) Background: Influenza A Virus (IAV) uses host cellular proteins during replication in host cells. IAV infection causes elevated expression of chloride intracellular channel protein 1 (CLIC1) in lung epithelial cells, but the importance of this protein in IAV replication is unknown. (2) In this study, we determined the role of CLIC1 in IAV replication by investigating the effects of CLIC1 knockdown (KD) on IAV viral protein translation, genomic RNA transcription, and host cellular proteome dysregulation. (3) Results: CLIC1 KD in A549 human lung epithelial cells resulted in a significant decrease in progeny supernatant IAV, but virus protein expression was unaffected. However, a significantly larger number of viral RNAs accumulated in CLIC1 KD cells. Treatment with a CLIC1 inhibitor also caused a significant reduction in IAV replication, suggesting that CLIC1 is an important host factor in IAV replication. SomaScan®, which measures 1322 proteins, identified IAV-induced dysregulated proteins in wild-type cells and in CLIC1 KD cells. The expression of 116 and 149 proteins was significantly altered in wild-type and in CLIC1 KD cells, respectively. A large number of the dysregulated proteins in CLIC1 KD cells were associated with cellular transcription and predicted to be inhibited during IAV replication. (4) Conclusions: This study suggests that CLIC1 is involved in later stages of IAV replication. Further investigation should clarify mechanism(s) for the development of anti-IAV drugs targeting CLIC1 protein.

Retrograde AAV-mediated gene modulation reveals chloride intracellular channel proteins as potent regulators of retinal ganglion cell death.

Most projection neurons, including retinal ganglion cells (RGCs), undergo cell death after axotomy proximal to the cell body. Specific RGC subtypes, such as ON-OFF direction selective RGCs (ooDSGCs) are particularly vulnerable, whereas intrinsically photosensitive RGCs (ipRGCs) exhibit resilience to axonal injury. Through the application of RNA sequencing and fluorescent in situ hybridization, we show that the expression of chloride intracellular channel protein 1 and 4 (Clic1 and Clic4) are highly increased in the ooDSGCs after axonal injury. Toward determining a gene's role in RGCs, we optimized the utility and efficacy of adenovirus associated virus (AAV)-retro expressing short hairpin RNA (shRNA). Injection of AAV2-retro into the superior colliculus results in efficient shRNA expression in RGCs. Incorporating histone H2B gene fused with mGreenLantern results in bright nuclear reporter expression, thereby enhancing single RGC identification and cell quantitation in live retinas. Lastly, we demonstrate that AAV2-retro mediated knockdown of both Clic1 and Clic4 promotes RGC survival after injury. Our findings establish an integrated use of AAV2-retro-shRNA and real-time fundus imaging and reveal CLICs' contribution to RGC death.

Intracellular chloride channel 1 and tumor.

As the major intracellular anion, chloride plays an important role in maintaining intracellular and extracellular ion homeostasis, osmotic pressure, and cell volume. Intracellular chloride channel 1, which has the physiological role of forming membrane proteins in the lipid bilayer and playing ion channels, is a hot research topic in recent years. It has been found that CLIC1 does not only act as an ion channel but also participates in cell cycle regulation, apoptosis, and intracellular oxidation; thus, it participates in the proliferation, invasion, and migration of various tumor cells in various systems throughout the body. At the same time, CLIC1 is highly expressed in tumor cells and is associated with malignancy and a poor prognosis. This paper reviews the pathological mechanisms of CLIC1 in systemic diseases, which is important for the early diagnosis, treatment, and prognosis of systemic diseases associated with CLIC1 expression.

Chloride intracellular channel 1 promotes esophageal squamous cell carcinoma proliferation via mTOR signalling.

OBJECTIVES: To investigate the clinical significance of Chloride Intracellular Channel 1 (CLIC1) expression in esophageal squamous cell carcinoma (ESCC) and its functional contribution and molecular mechanisms to the progression of ESCC. METHODS: CLIC1 expression was analyzed by immunohistochemistry (IHC) in a cohort of 86 ESCC tissue specimens and paired normal adjacent esophageal tissues. Associations between clinicopathological features of ESCC and CLIC1 expression were determined. In vitro analyses examined CLIC1 expression in the ESCC cell lines KYSE150 and TE1 using RT-PCR and Western blotting. The downstream pathways of CLIC1 were detected by lentiviral shRNA knockdown and subsequent proteomic analyses. CLIC1 siRNA knockdown was performed in ESCC cell lines KYSE150 and TE1 and the functional effects of CLIC1 on the growth and proliferation of ESCC cells were evaluated combined with cell viability and colony formation assays; the mTOR signaling pathway-related proteins were detected by Western blotting based on the previous proteomic data. RESULTS: CLIC1 expression was significantly increased in ex vivo ESCC tissues compared with corresponding normal tissues, and the up-regulation was associated with clinical tumor node metastasis (TNM) classifications. Knockdown of CLIC1 inhibited in vitro cell proliferation of ESCC cell lines KYSE150 and TE1. CLIC1 knockdown down-regulated the protein expression of p-mTOR and the downstream targets Rictor and p-4EBP1 in both KYSE150 and TE1 cell lines. And the CLIC1 knockdown induced inhibition of cell proliferation on ESCC cells could be rescued by mTOR overexpression. CONCLUSIONS: CLIC1 expression increases during esophageal carcinogenesis and it may functionally contribute to the progression of ESCC through growth promotion effects by promoting the mTOR and downstream signaling pathway. CLIC1 therefore constitutes a candidate molecular biomarker of ESCC.

Targeting Clic1 for the treatment of obesity: A novel therapeutic strategy to reduce food intake and body weight.

OBJECTIVE: Despite great advances in obesity therapeutics in recent years, there is still a need to identify additional therapeutic targets for the treatment of this disease. We previously discovered a signature of genes, including Chloride intracellular channel 1 (Clic1), whose expression was associated with drug-induced weight gain, and in these studies, we assess the effect of Clic1 inhibition on food intake and body weight in mice. METHODS: We studied the impact of Clic1 inhibition in mouse models of binge-eating, diet-induced obese mice and genetic models of obesity (Magel2 KO mice). RESULTS: Clic1 knockout (KO) mice ate significantly less and had a lower body weight than WT littermates when either fed chow or high fat diet. Furthermore, pharmacological inhibition of Clic1 in diet-induced obese mice resulted in suppression of food intake and promoted highly efficacious weight loss. Clic1 inhibition also reduced food intake in binge-eating models and hyperphagic Magel2 KO mice. We observed that chronic obesity resulted in a significant change in subcellular localization of Clic1 with an increased ratio of Clic1 in the membrane in the obese state. These observations provide a novel therapeutic strategy to block Clic1 translocation as a potential mechanism to reduce food intake and lower body weight. CONCLUSIONS: These studies attribute a novel role of Clic1 as a driver of food intake and overconsumption. In summary, we have identified hypothalamic expression of Clic1 plays a key role in food intake, providing a novel therapeutic target to treat overconsumption that is the root cause of modern obesity.

Corrigendum: Label-free LC-MS/MS proteomics analyses reveal CLIC1 as a predictive biomarker for bladder cancer staging and prognosis.

[This corrects the article DOI: 10.3389/fonc.2022.1102392.].

CLIC1 plasma concentration is associated with lymph node metastases in oral squamous cell carcinoma.

BACKGROUND: Previous studies have shown that the chloride intracellular channel 1 (CLIC1) protein is overexpressed in oral squamous cell carcinoma (OSCC) and nasopharyngeal carcinoma. Patients with these diseases had significantly higher CLIC1 plasma levels than healthy controls. OBJECTIVES: To determine the plasma concentration of CLIC1 in patients with OSCC and laryngeal squamous cell carcinoma (LSCC). MATERIAL AND METHODS: We collected blood samples from patients diagnosed with OSCC (n = 13) and LSCC (n = 7), as well as from healthy controls (n = 8). The blood samples were centrifuged to obtain plasma and stored at -80°C. The CLIC1 plasma concentration was determined using enzyme-linked immunosorbent assay (ELISA). RESULTS: The mean CLIC1 plasma concentration was higher in the OSCC group than in the LSCC and control groups. Patients with OSCC and nodal metastases had significantly higher CLIC1 plasma concentration levels than nonmetastatic patients (p < 0.0001; Tukey's multiple comparisons test) and controls (p = 0.0004). The CLIC1 concentration correlated significantly with the presence of nodal spread (p = 0.0003; Spearman's r = 0.8613) and overall TNM staging (p = 0.0167; Spearman's r = 0.6620). No differences in CLIC1 plasma levels were observed between the LSCC and control groups. The CLIC1 plasma concentration was not associated with age, sex, tumor stage, or tumor grade. CONCLUSIONS: There were no differences in CLIC1 plasma concentration between healthy controls and patients with LSCC. However, our findings suggest that the presence of this protein in plasma may be associated with lymphatic metastasis in patients with OSCC. More research is needed to confirm this possible association.

Multi-omics analysis reveals CLIC1 as a therapeutic vulnerability of gliomas.

Introduction: Despite advances in comprehending cancer biology, malignant gliomas remain incurable. The present work conducted a multi-omics analysis for investigating the significance of chloride intracellular channel 1 (CLIC1) in gliomas. Methods: Multi-omics data of glioma covering transcriptomics, genomics, DNA methylation and single-cell transcriptomics from multiple public cohorts were enrolled for analyzing CLIC1. In vitro experiments were conducted to measure apoptosis and cell mobility in U251 and U373 glioma cells following transfection of CLIC1 siRNAs. Results: Elevated CLIC1 expression was proven to stably and independently estimate worse survival outcomes. CLIC1 expression was higher in more advanced stage, wild-type IDH and unmethylated MGMT samples. Tumorigenic and anticancer immunity pathways were remarkably enriched in CLIC1-up-regulated tumors. Additionally, CLIC1 was positively linked with cancer-immunity cycle, stromal activation, DNA damage repair and cell cycle. Suppressing CLIC1 resulted in apoptosis and attenuated cell motility of glioma cells. More frequent genomic alterations were found in CLIC1-up-regulated tumors. CLIC1 expression presented a remarkably negative connection to DNA methylation. High CLIC1 expression samples were more sensitive to camptothecin, cisplatin, doxorubicin, erlotinib, paclitaxel, rapamycin, clofarabine, tanespimycin, methotrexate, everolimus, TAK-733, trametinib and AZD8330. Tumors with upregulated CLIC1 presented abundant immune cell infiltration, higher expression of immune-checkpoints and -modulators and similar transcriptome profiling, indicative of well response to immune-checkpoint blockade (ICB). Nevertheless, due to elevated TIDE score, tumors with CLIC1 upregulation appeared to be resistant to ICB. Single-cell analysis unveiled that CLIC1 was expressed ubiquitously in tumor cells and tumor microenvironment. Conclusions: Overall, CLIC1 was a promising treatment vulnerability in glioma.

Repression of linc01555 up-regulates angiomotin-p130 via the microRNA-122-5p/clic1 axis to impact vasculogenic mimicry-mediated chemotherapy resistance in small cell lung cancer.

Long non-coding ribonucleic acid 01555 (linc01555) is a brand-new long non-coding RNA (lncRNA) that acts a carcinogenic function in various cancers. However, its role in small cell lung cancer (SCLC) is uncertain. This research was to figure out the role of linc01555 in cisplatin (DDP) resistance of SCLC cells and its possible latent mechanism. After establishment of the resistant sub-strain H446/DDP or DMS-53/DDP, detection of linc01555, microRNA (miR)-122-5p and CLICl was done in the H446/DDP or DMS-53/DDP cell line. After intervention, cell biological functions were determined, as well as tube formation ability. The detection of angiomotin (Amot)-p130 and the validation of the regulatory mechanism were performed. Furthermore, tumor xenografts were applied in nude mice to evaluate the effect of linc01555 on DDP resistance in SCLC in vivo. Linc01555 was elevated in SCLC tissues and cells, and in H446/DDP cells or DMS-53/DDP vs. its parental cells; Restraining linc01555 or elevating miR-122-5p repressed the proliferation and metastasis of H446/DDP or DMS-53/DDP cells and vasculogenic mimicry (VM) formation. CLIC1 mediated miR-122-5p to influence the occurrence and development of SCLC. Linc01555 competitively combined with miR-122-5p, which targeted CLIC1. Refrained linc01555 elevated Amot-p130 via the miR-122-5p/CLIC1 axis. Reduced linc01555 refrained tumor growth and DDP resistance in vivo.In short, linc01555 may cause changes in DDP resistance via miR-122-5p/CLIC1 in SCLC. The finding may offer drug targets for SCLC resistance.

Inhibition of chloride intracellular channel protein 1 (CLIC1) ameliorates liver fibrosis phenotype by activating the Ca2+-dependent Nrf2 pathway.

Persistent damage to liver cells leads to liver fibrosis, which is characterized by the accumulation of scar tissue in the liver, ultimately leading to cirrhosis and serious complications. Because it is difficult to reverse cirrhosis once it has progressed, the primary focus has been on preventing the progression of liver fibrosis. However, studies on therapeutic agents for liver fibrosis are still lacking. Here, we investigated that the natural dipeptide cyclic histidine-proline (CHP, also known as diketopiperazine) shows promising potential as a therapeutic agent in models of liver injury by inhibiting the progression of fibrosis through activation of the Nrf2 pathway. To elucidate the underlying biological mechanism of CHP, we used the Cellular Thermal Shift Assay (CETSA)-LC-MS/MS, a label-free compound-based target identification platform. Chloride intracellular channel protein 1 (CLIC1) was identified as a target whose thermal stability is increased by CHP treatment. We analyzed the direct interaction of CHP with CLIC1 which revealed a potential interaction between CHP and the E228 residue of CLIC1. Biological validation experiments showed that knockdown of CLIC1 mimicked the antioxidant effect of CHP. Further investigation using a mouse model of CCl4-induced liver fibrosis in wild-type and CLIC1 KO mice revealed the critical involvement of CLIC1 in mediating the effects of CHP. Taken together, our results provide evidence that CHP exerts its anti-fibrotic effects through specific binding to CLIC1. These insights into the mechanism of action of CHP may pave the way for the development of novel therapeutic strategies for fibrosis-related diseases.

CLIC1 Drives Angiogenesis in Hepatocellular Carcinoma by Modulating VEGFA.

Background: Chloride intracellular channel 1 (CLIC1) is upregulated in hepatocellular carcinoma (HCC). The present study aimed to investigate the role of CLIC1 in HCC angiogenesis. Materials and Methods: Immunohistochemistry (IHC) was used to test the expression of CLIC1 and CD34 in 67 pairs of HCC and paracarcinoma tissues. The prognosis data of the patients were used to analyze the clinical relevance of CLIC1. We built a coculture system of HCC cells and endothelial cells to explore the migration of endothelial cells. Conditioned media (CMs) from HCC cells was then collected to assess endothelial cell migration. Experiments were then conducted to confirm the relationship between CLIC1 and angiogenesis in a subcutaneous tumor model. Results: CLIC1 expression was higher in HCC tumor tissues than in paracarcinoma tissues. Patients with increased CLIC1 expression showed a higher microvascular density (MVD; P = .013). Kaplan-Meier curves indicated that patients with lower expression of CLIC1 had better overall survival (P < .001) and recurrence-free survival (P = .046). Vascular endothelial growth factor A (VEGFA) in CMs from CLIC1-knockdown cells was lower than in the control group, while VEGFA in CMs from CLIC1 overexpression cells was higher than in the control group. CMs from CLIC1 overexpression cell lines promote the in vitro migration of EA.hy926 cells. Meanwhile, adding Bevacizumab to CMs from CLIC1 overexpression cells significantly inhibited this migration. The growth of xenograft tumors derived from CLIC1-knockdown Huh7 cells was restrained compared with the control group (P < .001). IHC staining showed MVD was higher in tumors with CLIC1 overexpression. Conclusion: CLIC1 is a promising biomarker for predicting the prognosis of HCC patients, and expression of CLIC1 correlates with angiogenesis in HCC through regulating VEGFA.

Chloride Intracellular Channel 1 is a Potential Biomarker for Breast Cancer.

Purpose: Multiple reports have demonstrated that highly expressed chloride intracellular channel 1 (CLIC1) exists in a range of malignant tumors and is involved in proliferation, invasion, and migration of cancer cells. There are few studies on CLIC1 and breast cancer (BC). The purpose of this research was to evaluate the expression level of CLIC1 in BC and its impact on prognosis of BC patients. Patients and Methods: Differences in CLIC1 expression levels in 25 pairs of BC and corresponding paracancerous specimens were tested by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot (WB). Immunohistochemistry (IHC) was performed to discuss the relevance between CLIC1 expression in BC tissue chips and clinicopathological parameters of BC patients. The effect of CLIC1 expression on patient prognosis was evaluated by Kaplan-Meier survival curve and Cox regression analysis. Receiver operating characteristic (ROC) curve assessed the diagnostic performance of CLIC1 for BC. Results: The experimental results of qRT-PCR and WB demonstrated that CLIC1 was highly expressed in BC tissues. IHC results showed that overexpression of CLIC1 was strictly correlated with tumor size, TNM classification, pathological grade, lymph node metastasis and Ki67. Patients with lower CLIC1 expression had longer overall survival (OS) and progression-free survival (PFS). Cox regression analysis and ROC curve confirmed that CLIC1 could independently influence the prognosis of BC patients and might have diagnostic efficiency. Conclusion: Overexpressed CLIC1 is closely related to the progression of BC and the poor prognosis of the patients, suggesting that it may act as a potential biological diagnostic index for BC.