CLIC1 overexpression is associated with poor prognosis in gallbladder cancer

Research progress on prognostic factors of gallbladder carcinoma

BACKGROUND

Gallbladder carcinoma is the most common malignant tumor of the biliary system, and has a poor overall prognosis. Poor prognosis in patients with gallbladder carcinoma is associated with the aggressive nature of the tumor, subtle clinical symptoms, ineffective adjuvant treatment, and lack of reliable biomarkers.

PURPOSE

Therefore, evaluating the prognostic factors of patients with gallbladder carcinoma can help improve diagnostic and treatment methods, allowing for tailored therapies that could benefit patient survival.

METHODS

This article systematically reviews the factors affecting the prognosis of gallbladder carcinoma, with the aim of evaluating prognostic risk in patients.

CONCLUSION

A comprehensive and in-depth understanding of prognostic indicators affecting patient survival is helpful for assessing patient survival risk and formulating personalized treatment plans.

Chloride intracellular channels in oncology as potential novel biomarkers and personalized therapy targets: a systematic review

Background

The chloride intracellular channels (CLICs) family includes six ion channels (CLIC1-CLIC6) expressed on the cellular level and secreted into interstitial fluid and blood. They are involved in the physiological functioning of multiple systems as well as the pathogenetic processes of cancer. CLICs play essential roles in the tumor microenvironment. The current systematic review aimed at identifying and summarizing the research of CLICs in oncology on clinical material to assess CLICs' potential as novel biomarkers and personalized therapy targets.

Materials and methods

The authors systematically searched the PubMed database for original articles concerning CLIC research on clinical material of all types of cancer - fluids and tissues.

Results

Fifty-three articles investigating in summary 3944 clinical samples were qualified for the current review. Studied material included 3438 tumor samples (87%), 437 blood samples (11%), and 69 interstitial fluid samples (2%). Studies investigated 21 cancer types, mostly hepatocellular carcinoma, colorectal, ovarian, and gastric cancer. Importantly, CLIC1, CLIC2, CLIC3, CLIC4, and CLIC5 were differently expressed in cancerous tissues and patients' blood compared to healthy controls. Moreover, CLICs were found to be involved in several cancer-associated signaling pathways, such as PI3K/AKT, MAPK/ERK, and MAPK/p38.

Conclusion

CLIC family members may be candidates for potential novel cancer biomarkers due to the contrast in their expression between cancerous and healthy tissues and secretion to the interstitial fluid and blood. CLICs are investigated as potential therapeutic targets because of their involvement in cancer pathogenesis and tumor microenvironment.

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

Introduction

Bladder cancer (BC) is a significant carcinoma of the urinary system that has a high incidence of morbidity and death owing to the challenges in accurately identifying people with early-stage BC and the lack of effective treatment options for those with advanced BC. Thus, there is a need to define new markers of prognosis and prediction.

Methods

In this study, we have performed a comprehensive proteomics experiment by label-free quantitative proteomics to compare the proteome changes in the serum of normal people and bladder cancer patients-the successful quantification of 2064 Quantifiable proteins in total. A quantitative analysis was conducted to determine the extent of changes in protein species' relative intensity and reproducibility. There were 43 upregulated proteins and 36 downregulated proteins discovered in non-muscle invasive bladder cancer and normal individuals. Sixty-four of these proteins were elevated, and 51 were downregulated in muscle-invasive and non-muscle-invasive bladder cancer, respectively. Functional roles of differentially expressed proteins were annotated using Gene Ontology (GO) and Clusters of Orthologous Groups of Proteins (COG). To analyze the functions and pathways enriched by differentially expressed proteins, GO enrichment analysis, protein domain analysis, and KEGG pathway analysis were performed. The proteome differences were examined and visualized using radar plots, heat maps, bubble plots, and Venn diagrams.

Results

As a result of combining the Venn diagram with protein-protein interactions (PPIs), Chloride intracellular channel 1 (CLIC1) was identified as the primary protein. Using the Gene Set Cancer Analysis (GSCA) website, the influence of CLIC1 on immune infiltration was analyzed. A negative correlation between CD8 naive and CLIC1 levels was found. For validation, immunohistochemical (IHC), qPCR, and western blotting (WB) were performed.Further, we found that CLIC1 was associated with a poor prognosis of bladder cancer in survival analysis.

Discussion

Our research screened CLIC1 as a tumor-promoting protein in bladder cancer for the first time using serum mass spectrometry. And CLIC1 associated with tumor stage, and immune infiltrate. The prognostic biomarker and therapeutic target CLIC1 may be new for bladder cancer patients.

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.

Comprehensive analysis of clinical prognosis and CLIC1 immune invasion in lung adenocarcinoma

BACKGROUND

Chloride intracellular channel 1 (CLIC1) plays an important role in the process of cell epithelial transport, and is also involved in tumor invasion and metastasis. Due to its aberrant expression in cancer, the mechanism of action of CLIC1 in cancer has been carefully studied. In this study, we tried to investigate the relationship between CLIC1 and lung adenocarcinoma (LUAD).

METHODS

The RNA-sequencing data and clinical information of CLIC1 in lung adenocarcinoma were collected from the the cancer genome altas (TCGA) database and analyzed with R software. Paired t test and Mann-Whitney U test were used to detect differences between LUAD tissue and adjacent normal tissue, and the pROC software package performed reactive oxygen species (ROC) curves to detect cutoff values for CLIC1. The expression of CLIC1 in normal human tissues was extracted from the human protein altas (HPA) database, and analyzed clinical proteomic tumor analysis consortium by using UALCAN programme. The relationship between CLIC1 and LUAD was explored by enrichment analysis using gene oncology and Kyoto encyclopedia of genes and genomes. The tumor immunity estimation resource (TIMER) and integrated repository portal for tumor-immune system interactions (TISIDB) databases were used to analyze the correlation between CLIC1 and LUAD immune cell infiltration. Survival analysis of CLIC1 in LUAD was assessed by the PrognoScan database.

RESULTS

Compared with normal tissues, both mRNA (messenger Ribose Nucleic Acid) and protein of CLIC1 were overexpressed in LUAD, which was associated with shorter overall survial (OS). In addition, CLIC1 expression was in connection with some clinical-pathological characteristics like tumor node metatasis stages and lymph node metastases. What's more, CLIC1 may play a role in the immune infiltration of LUAD.

CONCLUSION

In summary, CLIC1 is up-regulated in LUAD and is associated with tumor metastasis, tumor staging, and OS. It may be regarded as a novel marker for prognostic judgement in LUAD.

Chloride Channels and Transporters: Roles beyond Classical Cellular Homeostatic pH or Ion Balance in Cancers

Simple Summary

Roles of chloride-associated transporters have been raised in various cancers. Although complicated ion movements, crosstalk among channels/transporters through homeostatic electric regulation, difficulties with experimental implementation such as activity measurement of intracellular location were disturbed to verify the precise modulation of channels/transporters, recently defined cancerous function and communication with tumor microenvironment of chloride channels/transporters should be highlighted beyond classical homeostatic ion balance. Chloride-associated transporters as membrane-associated components of chloride movement, regulations of transmembrane member 16A, calcium-activated chloride channel regulators, transmembrane member 206, chloride intracellular channels, voltage-gated chloride channels, cystic fibrosis transmembrane conductance regulator, voltage-dependent anion channel, volume-regulated anion channel, and chloride-bicarbonate exchangers are discussed.

Abstract

The canonical roles of chloride channels and chloride-associated transporters have been physiologically determined; these roles include the maintenance of membrane potential, pH balance, and volume regulation and subsequent cellular functions such as autophagy and cellular proliferative processes. However, chloride channels/transporters also play other roles, beyond these classical function, in cancerous tissues and under specific conditions. Here, we focused on the chloride channel-associated cancers and present recent advances in understanding the environments of various types of cancer caused by the participation of many chloride channel or transporters families and discuss the challenges and potential targets for cancer treatment. The modulation of chloride channels/transporters might promote new aspect of cancer treatment strategies.

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.

Specific binding-induced modulation of the XCL1 metamorphic equilibrium

The metamorphic protein XCL1 switches between two distinct native structures with different functions in the human immune system. This structural interconversion requires complete rearrangement of all hydrogen bonding networks, yet fold-switching occurs spontaneously and reversibly in solution. One structure occupies the canonical α-β chemokine fold and binds XCL1's cognate G-protein coupled receptor, while the other structure occupies a dimeric, all-β fold that binds glycosaminoglycans and has antimicrobial activity. Both of these functions are important for the biologic role of XCL1 in the immune system, and each structure is approximately equally populated under near-physiologic conditions. Recent work has begun to illuminate XCL1's role in combatting infection and cancer. However, without a way to control XCL1's dynamic structural interconversion, it is difficult to study the role of XCL1 fold-switching in human health and disease. Thus, a molecular tool that can regulate the fractional population of the two XCL1 structures is needed. Here, we find by heparin affinity chromatography and NMR that an engineered XCL1 variant called CC5 can trigger a dose-dependent shift in XCL1's metamorphic equilibrium such that the receptor binding structure is depleted, and the antimicrobial structure is more heavily populated. This shift likely occurs due to formation of XCL1-CC5 heterodimers in which both protomers occupy the β-sheet structure. These findings lay the groundwork for future studies seeking to understand the functional role of XCL1 metamorphosis, as well as studies screening for a drug-like molecule that can therapeutically target XCL1 by tuning its metamorphic equilibrium. Moreover, the proof of concept presented here suggests that protein metamorphosis is druggable, opening numerous avenues for controlling biological function of metamorphic proteins by altering the population of their multiple native states.

Chloride intracellular channels as novel biomarkers for digestive system tumors (Review)

Digestive system malignant tumors are common tumors, and the traditional treatment methods for these tumors include surgical resection, radiotherapy, chemotherapy, and molecularly targeted drugs. However, diagnosis remains challenging, and the early detection of postoperative recurrence is complicated. Therefore, it is necessary to explore novel biomarkers to facilitate clinical diagnosis and treatment. Accumulating evidence supports the crucial role of chloride channels in the development of multiple types of cancers. Given that chloride channels are widely expressed and involved in cell proliferation, apoptosis and cell cycle, among other processes, they may serve as a promising diagnostic and therapeutic target. Chloride intracellular channels (CLICs) are a class of chloride channels that are upregulated or downregulated in certain types of cancer. Furthermore, in certain cases, during cell cycle progression, the localization and function of the cytosolic form of the transmembrane proteins of CLICs are also altered, which may provide a key target for cancer therapy. The aim of the present review was to focus on CLICs as biomarkers for digestive system tumors.

Transmembrane Chloride Intracellular Channel 1 (tmCLIC1) as a Potential Biomarker for Personalized Medicine

Identification of potential pathological biomarkers has proved to be essential for understanding complex and fatal diseases, such as cancer and neurodegenerative diseases. Ion channels are involved in the maintenance of cellular homeostasis. Moreover, loss of function and aberrant expression of ion channels and transporters have been linked to various cancers, and to neurodegeneration. The Chloride Intracellular Channel 1 (CLIC1), CLIC1 is a metamorphic protein belonging to a partially unexplored protein superfamily, the CLICs. In homeostatic conditions, CLIC1 protein is expressed in cells as a cytosolic monomer. In pathological states, CLIC1 is specifically expressed as transmembrane chloride channel. In the following review, we trace the involvement of CLIC1 protein functions in physiological and in pathological conditions and assess its functionally active isoform as a potential target for future therapeutic strategies.

Acetylation-stabilized chloride intracellular channel 1 exerts a tumor-promoting effect on cervical cancer cells by activating NF-κB

PURPOSE

Cervical cancer remains a major cause of cancer-related death in women, especially in developing countries. Previously, we found that the acetylation levels of chloride intracellular channel 1 (CLIC1) at lysine 131 were increased in cervical cancer tissues using a label-free proteomics approach. The aim of this study was to further determine the role of CLIC1 expression and its acetylation in cervical cancer.

METHODS

CLIC1 expression and its implications for the prognosis of cervical cancer were analyzed using primary patient samples and cells, and the Gene Expression Profiling Interactive Analysis (GEPIA) database (gepia.cancer-pku.cn). The effect of CLIC1 on cervical cancer cells was evaluated using Cell Counting Kit (CCK)-8, flow cytometry, scratch wound healing, transwell, Western blotting and co-immunoprecipitation (Co-IP) assays. In vivo tumor growth was assessed using mouse xenograft models.

RESULTS

We found that CLIC1 expression was increased in cervical cancer tissues and cells and that patients with a high CLIC1 expression tended to have a shorter overall survival time. Knockdown of CLIC1 significantly reduced in vitro cervical cancer cell proliferation, migration and invasion, and in vivo tumorigenesis. At the molecular level, we found that nuclear factor kappa B (NF-κB) activity was positively regulated by CLIC1. Pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB, attenuated the tumor-promoting effect of CLIC1. Moreover, we found that CLIC1 acetylation at K131 was upregulated in cervical cancer cells, which stabilized CLIC1 by inhibiting its ubiquitynation. Substitution of K131 inhibited CLIC1 ubiquitynation and promoted in vitro cervical cancer cell proliferation, migration and invasion, and in vivo tumor growth. In addition, we found that acetyltransferase HAT1 was responsible for CLIC1 acetylation at K131.

CONCLUSION

Our data indicate that CLIC1 acts as a tumor promoter in cervical cancer, suggesting a potential treatment strategy for cervical cancer by regulating CLIC1 expression and/or acetylation.

CLIC1 recruits PIP5K1A/C to induce cell-matrix adhesions for tumor metastasis

Membrane protrusion and adhesion to the extracellular matrix, which involves the extension of actin filaments and formation of adhesion complexes, are the fundamental processes for cell migration, tumor invasion, and metastasis. How cancer cells efficiently coordinate these processes remains unclear. Here, we showed that membrane-targeted chloride intracellular channel 1 (CLIC1) spatiotemporally regulates the formation of cell-matrix adhesions and membrane protrusions through the recruitment of PIP5Ks to the plasma membrane. Comparative proteomics identified CLIC1 upregulated in human hepatocellular carcinoma (HCC) and associated with tumor invasiveness, metastasis, and poor prognosis. In response to migration-related stimuli, CLIC1 recruited PIP5K1A and PIP5K1C from the cytoplasm to the leading edge of the plasma membrane, where PIP5Ks generate a phosphatidylinositol 4,5-bisphosphate-rich (PIP2-rich) microdomain to induce the formation of integrin-mediated cell-matrix adhesions and the signaling for cytoskeleon extension. CLIC1 silencing inhibited the attachment of tumor cells to culture plates and the adherence and extravasation in the lung alveoli, resulting in suppressed lung metastasis in mice. This study reveals what we believe is an unrecognized mechanism that spatiotemporally coordinates the formation of both lamellipodium/invadopodia and nascent cell-matrix adhesions for directional migration and tumor invasion/metastasis. The unique traits of upregulation and membrane targeting of CLIC1 in cancer cells make it an excellent therapeutic target for tumor metastasis.

Chloride intracellular channel 1 cooperates with potassium channel EAG2 to promote medulloblastoma growth

Ion channels represent a large class of drug targets, but their role in brain cancer is underexplored. Here, we identify that chloride intracellular channel 1 (CLIC1) is overexpressed in human central nervous system malignancies, including medulloblastoma, a common pediatric brain cancer. While global knockout does not overtly affect mouse development, genetic deletion of CLIC1 suppresses medulloblastoma growth in xenograft and genetically engineered mouse models. Mechanistically, CLIC1 enriches to the plasma membrane during mitosis and cooperates with potassium channel EAG2 at lipid rafts to regulate cell volume homeostasis. CLIC1 deficiency is associated with elevation of cell/nuclear volume ratio, uncoupling between RNA biosynthesis and cell size increase, and activation of the p38 MAPK pathway that suppresses proliferation. Concurrent knockdown of CLIC1/EAG2 and their evolutionarily conserved channels synergistically suppressed the growth of human medulloblastoma cells and Drosophila melanogaster brain tumors, respectively. These findings establish CLIC1 as a molecular dependency in rapidly dividing medulloblastoma cells, provide insights into the mechanism by which CLIC1 regulates tumorigenesis, and reveal that targeting CLIC1 and its functionally cooperative potassium channel is a disease-intervention strategy.

Ion Channels in Cancer: Orchestrators of Electrical Signaling and Cellular Crosstalk

Ion channels are pore-forming transmembrane proteins that govern ion flux to regulate a myriad of biological processes in development, physiology, and disease. Across various types of cancer, ion channel expression and activity are often dysregulated. We review the contribution of ion channels to multiple stages of tumorigenesis based on data from in vivo model systems. As intertumoral and intratumoral heterogeneities are major obstacles in developing effective therapies, we provide perspectives on how ion channels in tumor cells and their microenvironment represent targetable vulnerabilities in the areas of tumor-stromal cell interactions, cancer neuroscience, and cancer mechanobiology.

The Interplay of Dysregulated pH and Electrolyte Imbalance in Cancer

Cancer cells and tissues have an aberrant regulation of hydrogen ion dynamics driven by a combination of poor vascular perfusion, regional hypoxia, and increased the flux of carbons through fermentative glycolysis. This leads to extracellular acidosis and intracellular alkalinization. Dysregulated pH dynamics influence cancer cell biology, from cell transformation and tumorigenesis to proliferation, local growth, invasion, and metastasis. Moreover, this dysregulated intracellular pH (pHi) drives a metabolic shift to increased aerobic glycolysis and reduced mitochondrial oxidative phosphorylation, referred to as the Warburg effect, or Warburg metabolism, which is a selective feature of cancer. This metabolic reprogramming confers a thermodynamic advantage on cancer cells and tissues by protecting them against oxidative stress, enhancing their resistance to hypoxia, and allowing a rapid conversion of nutrients into biomass to enable cell proliferation. Indeed, most cancers have increased glucose uptake and lactic acid production. Furthermore, cancer cells have very dysregulated electrolyte balances, and in the interaction of the pH dynamics with electrolyte, dynamics is less well known. In this review, we highlight the interconnected roles of dysregulated pH dynamics and electrolytes imbalance in cancer initiation, progression, adaptation, and in determining the programming and reprogramming of tumor cell metabolism.

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.

CLIC1 and CLIC4 complement CA125 as a diagnostic biomarker panel for all subtypes of epithelial ovarian cancer

New plasma and tissue biomarkers of epithelial ovarian cancer (EOC) could improve early diagnosis and post-diagnosis clinical management. Here we investigated tissue staining and tissue secretion of CLIC1 and CLIC4 across EOC subtypes. CLIC1 and CLIC4 are two promising biomarkers we previously showed were elevated in EOC patient sera. Individually, CLIC1 or CLIC4 stained larger percentages of malignant tumors across all EOC subtypes compared with CA125, particularly early stage and mucinous tumors. CLIC4 also stained benign tumors but staining was limited to nuclei; whereas malignant tumors showed diffuse cellular staining of stromal and tumor cells. Both proteins were shed by all EOC subtypes tumors in short term organ culture at more consistent levels than CA125, supporting their potential as pan-subtype serum and tissue biomarkers. Elevated CLIC4 expression, but not CLIC1 expression, was a negative indicator of patient survival, and CLIC4 knockdown in cultured cells decreased cell proliferation and migration indicating a potential role in tumor progression. These results suggest CLIC1 and CLIC4 are promising serum and tissue biomarkers as well as potential therapeutic targets for all EOC subtypes. This justifies development of high throughput serum/plasma biomarker assays to evaluate utility of a biomarker panel consisting of CLIC1, CLIC4 and CA125.

Chloride intracellular channel 1 as a switch among tumor behaviors in human esophageal squamous cell carcinoma

Background: Recent studies have reported important roles for chloride intracellular channel 1 (CLIC1) in various cancers; however, its involvement in esophageal squamous cell carcinoma (ESCC) remains unclear. The aim of the present study was to investigate the role of CLIC1 in human ESCC. Methods: CLIC1 expression in human ESCC cell lines was analyzed by Western blotting. Knockdown experiments were conducted with CLIC1 siRNA, and their effects on cell proliferation, the cell cycle, apoptosis, migration, and invasion were analyzed. The gene expression profiles of cells were analyzed using a microarray analysis. An immunohistochemical analysis was performed on 61 primary tumor samples obtained from ESCC patients who underwent esophagectomy. Results: ESCC cells strongly expressed CLIC1. The depletion of CLIC1 using siRNA inhibited cell proliferation, induced apoptosis, and promoted cell migration and invasion. The results of the microarray analysis revealed that the depletion of CLIC1 regulated apoptosis via the TLR2/JNK pathway. Immunohistochemistry showed that CLIC1 was present in the cytoplasm of carcinoma cells, and that the very strong or very weak expression of CLIC1 was an independent poor prognostic factor. Conclusions: The present results suggest that the very strong expression of CLIC1 enhances tumor survival, while its very weak expression promotes cellular movement. The present study provides an insight into the role of CLIC1 as a switch among tumor behaviors in ESCC.

Identification and validation of differentially expressed proteins in epithelial ovarian cancers using quantitative proteomics

Ovarian cancer is the most lethal gynecological malignant tumor because of its high recurrence rate. In the present work, in order to find new therapeutic targets, we identified 8480 proteins in thirteen pairs of ovarian cancer tissues and normal ovary tissues through quantitative proteomics. 498 proteins were found to be differentially expressed in ovarian cancer, which involved in various cellular processes, including metabolism, response to stimulus and biosynthetic process. The expression levels of chloride intracellular channel protein 1 (CLIC1) and lectin galactoside-binding soluble 3 binding protein (LGALS3BP) in epithelial ovarian cancer tissues were significantly higher than those in normal ovary tissues as confirmed by western blotting and immunohistochemistry. The knockdown of CLIC1 in A2780 cell line downregulated expression of CTPS1, leading to the decrease of CTP and an arrest of cell cycle G1 phase, which results into a slower proliferation. CLIC1-knockdown can also slow down the tumor growth in vivo. Besides, CLIC1-knockdown cells showed an increased sensitivity to hydrogen peroxide and cisplatin, suggesting that CLIC1 was involved in regulation of redox and drug resistance in ovarian cancer cells. These results indicate CLIC1 promotes tumorgenesis, and is a potential therapeutic target in epithelial ovarian cancer treatment.

Decreased expression of hsa‑miR‑372 predicts poor prognosis in patients with gallbladder cancer by affecting chloride intracellular channel 1

It has been reported that hsa‑microRNA (miRNA/miR)‑372 functions as a tumor suppressor or oncogene in various digestive system tumors, however, its roles in gallbladder cancer (GBC) are yet to be established. The present study aimed to determine the expression and clinical relevance of hsa‑miR‑372 in GBC. The expression of hsa‑miR‑372 in 80 pairs of human GBC tissues and adjacent normal gallbladder tissues was measured by reverse transcription‑quantitative polymerase chain reaction. Subsequently, the associations between hsa‑miR‑372 expression levels and the clinicopathological characteristics of patients with GBC were determined using χ2 test. Furthermore, Kaplan‑Meier method and Cox regression analysis were performed to evaluate the association between hsa‑miR‑372 expression and the prognosis of patients with GBC. Furthermore, a dual‑luciferase reporter assay and western blot analysis were performed to predict and verify the target gene of hsa‑miR‑372. The results demonstrated that markedly lower hsa‑miR‑372 expression was observed in GBC tissues, which was associated with poor prognosis in patients with GBC. Downregulated expression of hsa‑miR‑372 was negatively associated with tumor histological grade, tumor‑node‑metastasis stage, lymph node metastasis and distant metastasis, however, no association was observed between reduced hsa‑miR‑372 expression and patient gender, age, tumor size and gallbladder stones. Multivariate Cox regression analysis revealed that hsa‑miR‑372 expression, histological grade and lymph node metastasis were independent prognostic factors for overall survival in patients with GBC. Chloride intracellular channel 1 (CLIC1) was previously reported to be an effective biomarker for predicting the prognosis of GBC. Notably, the results of the present study indicated that CLIC1 may be a direct target gene of hsa‑miR‑372. In conclusion, the current study provides the first statistically convincing evidence that downregulation of hsa‑miR‑372 may occur in GBC tissues, which may be associated with aggressive and progressive tumor behavior by affecting CLIC1 expression.

Differential expression pattern of protein markers for predicting chemosensitivity of dexamethasone-based chemotherapy of B cell acute lymphoblastic leukemia

Dexamethasone is considered as a direct chemotherapeutic agent in the treatment of pediatric acute lymphoblastic leukemia (ALL). Beside the advantages of the drug, some problems arising from the dose-related side effects are challenging issues during the treatment. Accordingly, the classification of patients to dexamethasone sensitive and resistance groups can help to select optimizing the therapeutic dose with the lowest adverse effects particularly in sensitive cases. For this purpose, we investigated inhibited proliferation and induced cytotoxicity in NALM-6 cells, as sensitive cells, after dexamethasone treatment. In addition, comparative protein expression analysis using the 2DE-MALDI-TOF MS technique was performed to identify the specific altered proteins. In addition, we evaluated mRNA expression levels of the identified proteins in bone-marrow samples from pediatric ALL patients using the real-time q-PCR method. Eventually, proteomic analysis revealed a combination of biomarkers, including capping proteins (CAPZA1 and CAPZB), chloride channel (CLIC1), purine nucleoside phosphorylase (PNP), and proteasome activator (PSME1), in response to the dexamethasone treatment. In addition, our results indicated low expression of identified proteins at both the mRNA and protein expression levels after drug treatment. Moreover, quantitative real-time PCR data analysis indicated that independent of the molecular subtypes of the leukemia, CAPZA1, CAPZB, CLIC1, and PNP expression levels were lower in ALL samples than normal samples, although PSME1 expression level was higher in ALL samples than normal samples. Furthermore, the expression level of all proteins (except PSME1) was different between high-risk and standard-risk patients that suggesting the prognostic value of them. In conclusion, our study suggests a panel of biomarkers comprising CAPZA1, CAPZB, CLIC1, PNP, and PSME1 as early diagnosis and treatment evaluation markers that may differentiate cancer cells which are presumably to benefit from dexamethasone-based chemotherapy and may facilitate the prediction of clinical outcome.

Chloride intracellular channel 1 regulates the antineoplastic effects of metformin in gallbladder cancer cells

Metformin is the most commonly used drug for type 2 diabetes and has potential benefit in treating and preventing cancer. Previous studies indicated that membrane proteins can affect the antineoplastic effects of metformin and may be crucial in the field of cancer research. However, the antineoplastic effects of metformin and its mechanism in gallbladder cancer (GBC) remain largely unknown. In this study, the effects of metformin on GBC cell proliferation and viability were evaluated using the Cell Counting Kit‐8 (CCK‐8) assay and an apoptosis assay. Western blotting was performed to investigate related signaling pathways. Of note, inhibition, knockdown and upregulation of the membrane protein Chloride intracellular channel 1 (CLIC1) can affect GBC resistance in the presence of metformin. Our data demonstrated that metformin apparently inhibits the proliferation and viability of GBC cells. Metformin promoted cell apoptosis and increased the number of early apoptotic cells. We found that metformin can exert growth‐suppressive effects on these cell lines via inhibition of p‐Akt activity and the Bcl‐2 family. Notably, either dysfunction or downregulation of CLIC1 can partially decrease the antineoplastic effects of metformin while upregulation of CLIC1 can increase drug sensitivity. Our findings provide experimental evidence for using metformin as an antitumor treatment for gallbladder carcinoma.

The role of microRNAs in gallbladder cancer

MicroRNAs (also referred to as miRNAs or miRs) play a crucial role in post-transcriptional gene regulation and serve as negative gene regulators by controlling a variety of target genes and regulating diverse biological processes, such as cell proliferation, invasion, migration and apoptosis. Aberrant expression of miRNAs is associated with the development and progression of cancer. Recent studies have reported that miRNAs may repress or promote the expression of cancer-related genes via several different signaling pathways in gallbladder cancer (GBC) patients and may function as tumor suppressors or oncogenes, thus providing a promising tool for the diagnosis and therapeutics of GBCs. In this review, we summarize the role of dysregulawted miRNA expression in the signaling pathways implicated in GBC and discuss the significant role of circulating miRNAs in GBC. Therefore, miRNAs may serve as novel therapeutic targets as well as diagnostic or prognostic markers in GBC.

CLIC1 antibody conjugated nanoscale contrast agent as a sensitive and targeted molecular imaging probe for gallbladder cancer diagnosis

CLIC1 antibody-conjugated nano-scale contrast agents exhibit a fast and sensitive detection of gallbladder tumors and may be used in the future as powerful targeted molecular imaging probes for gallbladder cancer diagnosis.

Chloride intracellular channel 1 (CLIC1) is activated and functions as an oncogene in pancreatic cancer

Chloride intracellular channel 1 (CLIC1), a newly discovered member of the chloride channel protein family, has been implicated in multiple human cancers. However, little is known with regard to its expression and biological functions in pancreatic cancer. In this study, we focused on the clinical significance and biological functions of CLIC1 in pancreatic cancer and found that this protein was overexpressed in pancreatic cancer tissues. Patients with CLIC1-positive tumours had worse overall survival than those with CLIC1-negative tumours. Furthermore, the treatment of pancreatic cancer cell lines with CLIC1-targeting siRNA oligonucleotides significantly reduced cell proliferation and diminished anchorage-independent growth on both soft agar and cell migration. These data indicate that CLIC1 acts as a putative oncogene in pancreatic cancer and may represent a novel diagnostic and therapeutic target for pancreatic cancer.

CLIC1 a novel biomarker of intraperitoneal metastasis in serous epithelial ovarian cancer

Early diagnosis of intraperitoneal metastasis is a pivot for survival of patients with serous epithelial ovarian cancers (SEOC). However, to date, there is lack of efficient molecular biomarker for early metastasis of SEOC. Here, we found that the expression of chloride intracellular channel 1 (CLIC1) is highly correlative with intraperitoneal metastasis. There is very low expression of CLIC1 in normal ovaries (NO), benign ovarian tumor (BOT), and primary ovarian cancer without metastasis (POCNM); but its expression is remarkably high in primary ovarian cancer with metastasis (POCM) omentum and peritoneal metastasis. Furthermore, for clinic prediction of intraperitoneal metastasis of SEOC, the sensitivity and specificity of CLIC1 overexpression were 97.4 and 88.1 %, respectively. Collectively, CLIC1 may be a potential sensitive and specific molecular biomarker for early diagnose for SEOC metastasis.