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Knockdown of CLAUDIN-6 Inhibited Apoptosis and Induced Proliferation of Bovine Cumulus Cells. Int J Mol Sci 2022; 23:ijms232113222. [PMID: 36362009 PMCID: PMC9656489 DOI: 10.3390/ijms232113222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/19/2022] [Accepted: 10/21/2022] [Indexed: 11/17/2022] Open
Abstract
This study aims to investigate the effects of CLAUDIN-6 (CLDN6) on cell apoptosis and proliferation of bovine cumulus cells (CCs). Immunofluorescence staining was used to localize CLDN6 protein in CCs. Three pairs of siRNA targeting CLDN6 and one pair of siRNA universal negative sequence as control were transfected into bovine CCs. Then, the effective siRNA was screened by real-time quantitative PCR (RT-qPCR) and Western blotting. The mRNA expression levels of apoptosis related genes (CASPASE-3, BAX and BCL-2) and proliferation related genes (PCNA, CDC42 and CCND2) were evaluated by RT-qPCR in CCs with CLDN6 knockdown. Cell proliferation, apoptosis and cell cycle were detected by flow cytometry with CCK-8 staining, Annexin V-FITC staining and propidium iodide staining, respectively. Results showed that the CLDN6 gene was expressed in bovine CCs and the protein was localized in cell membranes and cytoplasms. After CLDN6 was knocked down in CCs, the cell apoptosis rate significantly decreased and the pro-apoptotic genes BAX and CASPASE-3 were down-regulated significantly, whereas the anti-apoptotic gene BCL-2 was markedly up-regulated (p < 0.05). Additionally, CLDN6 knockdown significantly enhanced cell proliferation of CCs at 72 h after siRNA transfection. The mRNA levels of proliferation-related genes PCNA, CCND2 and CDC42 increased obviously in CCs with CLDN6 knockdown (p < 0.05). After CLDN6 was down-regulated, the percentage of CCs at S phase was significantly increased (p < 0.05). However, there was no remarkable difference in the percentages of cells at the G0/G1 phase and G2/M phase between CCs with or without CLDN6 knockdown (p > 0.05). Therefore, the expression of CLDN6 and its effects on cell proliferation, apoptosis and cell cycle of bovine CCs were first studied. CLDN6 low expression inhibited cell apoptosis, induced cell proliferation and cell cycle arrest of bovine CCs.
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Qu H, Jin Q, Quan C. CLDN6: From Traditional Barrier Function to Emerging Roles in Cancers. Int J Mol Sci 2021; 22:ijms222413416. [PMID: 34948213 PMCID: PMC8705207 DOI: 10.3390/ijms222413416] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/06/2021] [Accepted: 12/12/2021] [Indexed: 02/07/2023] Open
Abstract
Claudins (CLDNs) are the most important tight junction proteins, which are mainly expressed in endothelial cells or epithelial cells in a tissue-specific manner. As a member of the CLDNs family, CLDN6 is highly expressed in fetal tissues such as the stomach, pancreas, lung, and kidney, but is not expressed in corresponding adult tissues. The expression of CLDN6 is regulated by a variety of factors, including but not limited to stimuli and transcription factors, DNA methylation, and post-translational modifications. CLDN6 has been found to have a key role in the formation of barriers, especially the lung epithelial barrier and the epidermal permeability barrier (EPB). Importantly, the roles of CLDN6 in cancers have gained focus and are being investigated in recent years. Strong evidence indicates that the altered expression of CLDN6 is linked to the development of various cancers. Malignant phenotypes of tumors affected by CLDN6 include proliferation and apoptosis, migration and invasion, and drug resistance, which are regulated by CLDN6-mediated key signaling pathways. Given the important role in tumors and its low or no expression in normal tissues, CLDN6 is an ideal target for tumor therapy. This review aims to provide an overview of the structure and regulation of CLDN6, and its traditional barrier function, with a special emphasis on its emerging roles in cancers, including its impact on the malignant phenotypes, signal-modulating effects, the prognosis of tumor patients, and clinical applications in cancers.
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Li J. Targeting claudins in cancer: diagnosis, prognosis and therapy. Am J Cancer Res 2021; 11:3406-3424. [PMID: 34354852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/18/2021] [Indexed: 11/09/2022] Open
Abstract
Increasing evidence has linked claudins to signal transduction and tumorigenesis. The expression of claudins is frequently dysregulated in the context of neoplastic transformation, suggesting their promise as biomarkers for diagnosis and prognosis or targets for treatment. Claudin binders (Clostridium perfringens enterotoxin and monoclonal antibody) have been tested in preclinical experiments, and some of them have progressed into clinical trials involving patients with certain cancers. However, the clinical development of many of these agents has not advanced to clinical applications. Herein, I review the current status of preclinical and clinical investigations of agents targeting claudins for diagnosis, prognosis and therapy. I also discuss the potential of combining claudin binders with other currently approved therapeutic agents.
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Affiliation(s)
- Jian Li
- Department of General Surgery, The Third Hospital of Mianyang, Sichuan Mental Health Center Mianyang 621000, Sichuan, China
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Du H, Yang X, Fan J, Du X. Claudin 6: Therapeutic prospects for tumours, and mechanisms of expression and regulation (Review). Mol Med Rep 2021; 24:677. [PMID: 34296304 PMCID: PMC8335585 DOI: 10.3892/mmr.2021.12316] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 06/30/2021] [Indexed: 12/13/2022] Open
Abstract
Tight junctions (TJs) are an important component of cell connectivity; they maintain cell polarity, permeability and adhesion, and participate in the regulation of cell proliferation and differentiation. The claudin (CLDN) family is integral to TJs, and CLDN6 is an important member of this family. Abnormal expression of CLDN6 can destroy the integrity of TJs through various mechanisms and can serve multiple roles in the occurrence and development of tumours. CLDN6 is widely expressed in various tumours but rarely expressed in healthy adult tissues. The aim of this review is to critically examine the recent literature on CLDN6, including its structure, expression in different tumours, regulatory mechanisms and therapeutic prospects. Although some conclusions are controversial, in certain tumours, such as liver, ovarian, endometrial and oesophageal cancer, and atypical teratoid/rhabdoid tumours, research consistently shows that CLDN6 is expressed in tumour tissues but is not expressed or is expressed at low levels in surrounding tissues. In these tumours, CLDN6 has potential as a carcinoembryonic antigen and a therapeutic target.
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Affiliation(s)
- Huan Du
- Department of Oncology, Mianyang Central Hospital, Mianyang, Sichuan 621000, P.R. China
| | - Xiyue Yang
- Department of Oncology, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China
| | - Jinjia Fan
- Department of Oncology, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China
| | - Xiaobo Du
- Department of Oncology, Mianyang Central Hospital, Mianyang, Sichuan 621000, P.R. China
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Lin Z, Zhang X, Liu Z, Liu Q, Wang L, Lu Y, Liu Y, Wang M, Yang M, Jin X, Quan C. The distinct expression patterns of claudin-2, -6, and -11 between human gastric neoplasms and adjacent non-neoplastic tissues. Diagn Pathol 2013; 8:133. [PMID: 23919729 PMCID: PMC3751254 DOI: 10.1186/1746-1596-8-133] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 06/21/2013] [Indexed: 12/13/2022] Open
Abstract
Background Cancers have a multifactorial etiology a part of which is genetic. Recent data indicate that expression of the tight junction claudin proteins is involved in the etiology and progression of cancer. Methods To explore the correlations of the tight junction proteins claudin-2,-6, and −11 in the pathogenesis and clinical behavior of gastric cancer, 40 gastric cancer tissues and 28 samples of non-neoplastic tissues adjacent to the tumors were examined for expression of claudin-2,-6, and −11 by streptavidin-perosidase immunohistochemical staining method. Results The positive expression rates of claudin-2 in gastric cancer tissues and adjacent tissues were 25% and 68% respectively (P < 0.001). The positive expression rates of claudin-6 in gastric cancer tissues and adjacent tissues were 55% and 79% respectively (P = 0.045 < 0.05). In contrast, the positive expression rates of claudin-11 in gastric cancer tissues and gastric cancer adjacent tissues were 80% and 46% (P = 0.004 < 0.01). Thus in our study, the expression of claudin-2, and claudin-6 was down regulated in gastric cancer tissue while the expression of claudin-11 was up regulated. Correlations between claudin expression and clinical behavior were not observed. Conclusion Our study provides the first evidence that claudin-2,-6, and −11 protein expression varies between human gastric cancers and adjacent non-neoplastic tissues. Virtual slides The virtual slide(s) for this article can be found here:
http://www.diagnosticpathology.diagnomx.eu/vs/5470513569630744
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Affiliation(s)
- Zhe Lin
- Department of General Surgery, The Second Hospital of Jilin University, Changchun, Jilin, China
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Hasselblatt M, Isken S, Linge A, Eikmeier K, Jeibmann A, Oyen F, Nagel I, Richter J, Bartelheim K, Kordes U, Schneppenheim R, Frühwald M, Siebert R, Paulus W. High-resolution genomic analysis suggests the absence of recurrent genomic alterations other than SMARCB1 aberrations in atypical teratoid/rhabdoid tumors. Genes Chromosomes Cancer 2012; 52:185-90. [PMID: 23074045 DOI: 10.1002/gcc.22018] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Accepted: 09/18/2012] [Indexed: 01/09/2023] Open
Abstract
Atypical teratoid/rhabdoid tumor (AT/RT) is a rare malignant pediatric brain tumor characterized by genetic alterations affecting the SMARCB1 (hSNF5/INI1) locus in chromosome band 22q11.2. To identify potential additional genetic alterations, high-resolution genome-wide analysis was performed using a molecular inversion probe single-nucleotide polymorphism (MIP SNP) assay (Affymetrix OncoScan formalin-fixed paraffin-embedded express) on DNA isolated from 18 formalin-fixed paraffin-embedded archival samples. Alterations affecting the SMARCB1 locus could be demonstrated by MIP SNP in 15 out of 16 evaluable cases (94%). These comprised five tumors with homozygous deletions, six tumors with heterozygous deletions, and four tumors with copy number neutral loss of heterozygosity (LOH) involving chromosome band 22q11.2. Remarkably, MIB SNP analysis did not yield any further recurrent chromosomal gains, losses, or copy neutral LOH. On MIP SNP screening for somatic mutations, the presence of a SMARCB1 mutation (c.472C>T p.R158X) was confirmed, but no recurrent mutations of other cancer relevant genes could be identified. Results of fluorescence in situ hybridization, multiplex ligation-dependent probe amplification, and SMARCB1 sequencing were highly congruent with that of the MIP SNP assay. In conclusion, these data further suggest the absence of recurrent genomic alterations other than SMARCB1 in AT/RT.
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Affiliation(s)
- Martin Hasselblatt
- Institute of Neuropathology, University Hospital Münster, Münster, Germany.
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Xu X, Jin H, Liu Y, Liu L, Wu Q, Guo Y, Yu L, Liu Z, Zhang T, Zhang X, Dong X, Quan C. The expression patterns and correlations of claudin-6, methy-CpG binding protein 2, DNA methyltransferase 1, histone deacetylase 1, acetyl-histone H3 and acetyl-histone H4 and their clinicopathological significance in breast invasive ductal carcinomas. Diagn Pathol 2012; 7:33. [PMID: 22455563 PMCID: PMC3349567 DOI: 10.1186/1746-1596-7-33] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 03/29/2012] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Claudin-6 is a candidate tumor suppressor gene in breast cancer, and has been shown to be regulated by DNA methylation and histone modification in breast cancer lines. However, the expression of claudin-6 in breast invasive ductal carcinomas and correlation with clinical behavior or expression of other markers is unclear. We considered that the expression pattern of claudin-6 might be related to the expression of DNA methylation associated proteins (methyl-CpG binding protein 2 (MeCP2) and DNA methyltransferase 1 (DNMT1)) and histone modification associated proteins (histone deacetylase 1 (HDAC1), acetyl-histone H3 (H3Ac) and acetyl- histone H4 (H4Ac)). METHODS We have investigated the expression of claudin-6, MeCP2, HDAC1, H3Ac and H4Ac in 100 breast invasive ductal carcinoma tissues and 22 mammary gland fibroadenoma tissues using immunohistochemistry. RESULTS Claudin-6 protein expression was reduced in breast invasive ductal carcinomas (P < 0.001). In contrast, expression of MeCP2 (P < 0.001), DNMT1 (P = 0.001), HDAC1 (P < 0.001) and H3Ac (P = 0.004) expressions was increased. Claudin-6 expression was inversely correlated with lymph node metastasis (P = 0.021). Increased expression of HDAC1 was correlated with histological grade (P < 0.001), age (P = 0.004), clinical stage (P = 0.007) and lymph node metastasis (P = 0.001). H3Ac expression was associated with tumor size (P = 0.044) and clinical stage of cancers (P = 0.034). MeCP2, DNMT1 and H4Ac expression levels did not correlate with any of the tested clinicopathological parameters (P > 0.05). We identified a positive correlation between MeCP2 protein expression and H3Ac and H4Ac protein expression. CONCLUSIONS Our results show that claudin-6 protein is significantly down-regulated in breast invasive ductal carcinomas and is an important correlate with lymphatic metastasis, but claudin-6 down-regulation was not correlated with upregulation of the methylation associated proteins (MeCP2, DNMT1) or histone modification associated proteins (HDAC1, H3Ac, H4Ac). Interestingly, the expression of MeCP2 was positively correlated with the expression of H3Ac and H3Ac protein expression was positively correlated with the expression of H4Ac in breast invasive ductal carcinoma VIRTUAL SLIDES The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/4549669866581452.
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Affiliation(s)
- Xiaoming Xu
- The Key Laboratory of Pathobiology, Ministry of Education, Bethune Medical College, Jilin University, Changchun, Jilin, China
| | - Huiying Jin
- Department of Pathology, Jilin Oil Field General Hospital, Songyuan, Jilin, China
| | - Yafang Liu
- Department of Pathology, The First Bethune Hospital of Jilin University, Changchun, Jilin, China
| | - Li Liu
- Department of Pathology, Jilin Oil Field General Hospital, Songyuan, Jilin, China
| | - Qiong Wu
- Department of Pathology, The Third Bethune Hospital of Jilin University, Changchun, Jilin, China
| | - Yaxiong Guo
- The Key Laboratory of Pathobiology, Ministry of Education, Bethune Medical College, Jilin University, Changchun, Jilin, China
| | - Lina Yu
- The Key Laboratory of Pathobiology, Ministry of Education, Bethune Medical College, Jilin University, Changchun, Jilin, China
| | - Zhijing Liu
- The Key Laboratory of Pathobiology, Ministry of Education, Bethune Medical College, Jilin University, Changchun, Jilin, China
| | - Ting Zhang
- The Key Laboratory of Pathobiology, Ministry of Education, Bethune Medical College, Jilin University, Changchun, Jilin, China
| | - Xiaowei Zhang
- The Key Laboratory of Pathobiology, Ministry of Education, Bethune Medical College, Jilin University, Changchun, Jilin, China
| | - Xueyan Dong
- The Key Laboratory of Pathobiology, Ministry of Education, Bethune Medical College, Jilin University, Changchun, Jilin, China
| | - Chengshi Quan
- The Key Laboratory of Pathobiology, Ministry of Education, Bethune Medical College, Jilin University, Changchun, Jilin, China
- The Key Laboratory of Pathobiology, Ministry of Education, Bethune Medical College, Jilin University, 126 Xinmin street, Changchun, Jilin 130021, People's Republic of China
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Fleming AJ, Hukin J, Rassekh R, Fryer C, Kim J, Stemmer-Rachamimov A, Birks DK, Huang A, Yip S, Dunham C. Atypical teratoid rhabdoid tumors (ATRTs): the British Columbia's Children's Hospital's experience, 1986-2006. Brain Pathol 2012; 22:625-35. [PMID: 22188464 DOI: 10.1111/j.1750-3639.2011.00561.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
As "atypical teratoid rhabdoid tumors" (ATRTs) may mimic "small round blue cell tumors" (SRBCT), we reexamined our ATRT experience focusing upon INI-1 immunohistochemistry (IHC). All high-grade pediatric brain tumors occurring from 1986-2006 at our institution underwent INI-1 IHC. Clinicopathologic data from each INI-1 immunonegative case were reviewed. Additional genetic, epigenetic and IHC analyses (including interrogation of INI-1 and CLDN6) were performed on a subset of the INI-1 immunonegative cases. Twelve INI-1 IHC negative tumors were identified retrospectively, of which only two previously carried the diagnosis of ATRT. Overall, the clinicopathologic and genetic data supported the assertion that all 12 cases represented ATRT. Unexpectedly, three long-term survivors (4.2, 7.0 and 8.5 years) were identified. As hypothesized, "teratoid" and "rhabdoid" histologic features were relatively infrequent despite gross total resections in some cases. Methylation specific polymer chain reaction (PCR) (MSP) revealed a uniform methylation pattern across all cases and gene promoters tested (ie, MGMT, HIC1, MLH3 and RASSF1); notably, all cases demonstrated unmethylated MGMT promoters. Our data demonstate that a primitive non-rhabdoid histophenotype is common among ATRTs and highlights the diagnostic importance of INI-1 IHC. Epigenetically, the MGMT promoter is usually unmethylated in ATRT, suggesting that potential temozolomide-based chemotherapy may be of limited efficacy.
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Affiliation(s)
- Adam J Fleming
- Division of Hematology, Oncology and Bone Marrow Transplantation, British Columbia Children's Hospital, Vancouver, British Columbia, Canada
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Abstract
Claudins are tight junction proteins with claudin-6 (CLDN6) expression mostly restricted to embryonic and fetal life. Previously reported gene expression microarray analysis showed an increased level of CLDN6 in atypical teratoid rhabdoid tumors (AT/RT) compared with other central nervous system (CNS) tumors and sarcomas. However, there exist conflicting data on expression of CLDN6 as assessed by immunohistochemistry in CNS tumors. We established membranous staining as a specific and reproducible method for evaluating CLDN6 expression based on fetal and adolescent controls. We then evaluated a large group (257) of pediatric tumors using tissue microarrays, including: 47 malignant rhabdoid tumors (MRTs), (31 AT/RTs and 16 non-CNS MRTs); 67 small, round, blue cell tumors (10 Wilms tumors, 10 embryonal rhabdomyosarcomas, 10 neuroblastomas (NBs), 10 synovial sarcomas (SSs), 9 hepatoblastomas (HBs), 9 alveolar rhabdomyosarcomas, and 9 Ewings sarcomas); and 143 CNS tumors (24 medulloblastomas, 21 pilocytic astrocytomas, 14 astrocytomas grade II/III, 13 gangliogliomas, 12 glioblastomas, 12 ependymal tumors, 11 choroid plexus tumors, 10 meningiomas, 8 dysembryoplastic neuroepithelial tumors, 8 oligodendrogliomas, 4 craniopharyngiomas, 2 germinomas, 2 primitive neuroectodermal tumors (PNET), and 2 central neurocytomas). CLDN6 expression was seen in 12 of 31 (39%) AT/RTs, 7 of 16 (44%) non-CNS MRTs, 5 of 10 (50%) Wilms tumors, 1 of 9 (11%) HBs, 2 of 2 (100%) germinomas, 1 of 2 (50%) CNS PNETs, 1 of 24 (4%) medulloblastomas, and 1 of 10 (10%) meningiomas. Ten of 11 (91%) choroid plexus tumors showed apical staining but no concentric membranous staining. Although CLDN6 is expressed in both AT/RTs and MRTs, it is not a specific biomarker as it is expressed in a variety of other pediatric CNS and soft tissue tumors.
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