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Margot Zoller - One of the best experts on this subject based on the ideXlab platform.
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The importance of Claudin-7 palmitoylation on membrane subdomain localization and metastasis-promoting activities
Cell communication and signaling : CCS, 2015Co-Authors: Sarah Heiler, Margot Zoller, Florian ThumaAbstract:Background Claudin-7 (cld7), a tight junction (TJ) component, is also found basolaterally and in the cytoplasm. Basolaterally located cld7 is enriched in glycolipid-enriched membrane domains (GEM), where it associates with EpCAM (EpC). The conditions driving cld7 out of TJ into GEM, which is associated with a striking change in function, were not defined. Thus, we asked whether cld7 serines or palmitoylation affect cld7 location and protein, particularly EpCAM, associations.
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Claudin-7 promotes the epithelial-mesenchymal transition in human colorectal cancer.
Oncotarget, 2014Co-Authors: Rahel Philip, Margot Zoller, Sarah Heiler, Markus W. Büchler, Florian ThumaAbstract:// Rahel Philip 1 , Sarah Heiler 1 , Wei Mu 1 , Markus W. Buchler 2 , Margot Zoller 1 and Florian Thuma 1 1 Department of Tumor Cell Biology, University Hospital of Surgery, Heidelberg 2 University Hospital of General Surgery, Heidelberg Correspondence: Florian Thuma, email: // Margot Zoller, email: // Keywords : Colorectal cancer, Claudin 7, EpCAM, cancer initiating cells, metastasis Received : September 15, 2014 Accepted : December 02, 2014 Published : December 03, 2014 Abstract In colorectal cancer (CoCa) EpCAM is frequently associated with Claudin-7. There is evidence that tumor-promoting EpCAM activities are modulated by the association with Claudin-7. To support this hypothesis, Claudin-7 was knocked-down (kd) in HT29 and SW948 cells. HT29-cld7 kd and SW948-cld7 kd cells display decreased anchorage-independent growth and the capacity for holoclone-, respectively, sphere-formation is reduced. Tumor growth is delayed and cld7 kd cells poorly metastasize. In line with this, migratory and invasive potential of cld7 kd clones is strongly impaired, migration being inhibited by anti-CD49c, but not anti-EpCAM, although motility is reduced in EpCAM siRNA-treated cells. This is due to Claudin-7 recruiting EpCAM in glycolipid-enriched membrane fractions towards Claudin-7-associated TACE and presenilin2, which cleave EpCAM. The cleaved intracellular domain, EpIC, promotes epithelial-mesenchymal transition (EMT)-associated transcription factor expression, which together with fibronectin and vimentin are reduced in Claudin-7 kd cells. But, uptake of HT29 wt and SW948 wt exosomes by the Claudin-7 kd lines sufficed for transcription factor upregulation and for restoring motility. Thus, Claudin-7 contributes to motility and invasion and is required for recruiting EpCAM towards TACE/presenilin2. EpIC generation further supports motility by promoting a shift towards EMT. Notably, EMT features of cld7-competent metastatic CoCa cells can be transferred via exosomes to poorly metastatic cells.
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epcam associated Claudin 7 supports lymphatic spread and drug resistance in rat pancreatic cancer
International Journal of Cancer, 2013Co-Authors: Florian Thuma, Margot ZollerAbstract:Pancreatic cancer has a dismal prognosis because of early metastatic spread, a suggested feature of cancer-initiating cells (CIC). To control for a functional contribution of the pancreatic CIC-marker EpCAM, we explored metastasis formation by a stable EpCAM-knockdown (ASML-EpCkd) of the rat pancreatic adenocarcinoma line BSp73ASML (ASMLwt). As EpCAM associates with Claudin-7, an ASML-Claudin-7-knockdown (ASML-cld7kd) was included to differentiate between EpC- and EpC-cld7-mediated effects. The metastatic capacity of ASML-EpCkd and more pronounced ASML-cld7kd cells is strikingly reduced. EpC-associated cld7 interferes with EpC-mediated cell–cell adhesion and supports migration. This requires cld7 phosphorylation and formation of an EpC-cld7-tetraspanin-alpha6beta4 complex in glycolipid-enriched membrane domains (GEM), where cld7 associates via the tetraspanin-alpha6beta4 complex with phosphorylated ezrin. The association of cld7 with alpha6beta4 and cytoskeleton strongly stimulates tumor cell migration. However, EpC does not actively contribute. Instead, GEM-located cld7 associates with presenilin-2, which facilitates EpC cleavage and thereby tumor cell proliferation. Finally, the EpC-cld7 complex promotes drug resistance. Both EpC and cld7 support MAPK and JNK activation, such that in ASML-EpCkd and ASML-cld7kd cells an undue expansion of proapoptotic molecules is observed. Only cld7 promotes activation of the PI3K/Akt pathway by a strong downregulation of Pten. Accordingly, cisplatin treatment prolongs the survival time of ASML-cld7kd-bearing rats. Taken together, cld7 supports tumorigenic features of EpC by provoking EpC cleavage and thereby its cotranscription factor activity. On the other hand, only cld7 is directly engaged in motility and apoptosis resistance. Thus, at least in concern of migrating CIC, it is cld7 that acts as a CIC biomarker.
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EpCAM‐associated Claudin‐7 supports lymphatic spread and drug resistance in rat pancreatic cancer
International journal of cancer, 2013Co-Authors: Florian Thuma, Margot ZollerAbstract:Pancreatic cancer has a dismal prognosis because of early metastatic spread, a suggested feature of cancer-initiating cells (CIC). To control for a functional contribution of the pancreatic CIC-marker EpCAM, we explored metastasis formation by a stable EpCAM-knockdown (ASML-EpCkd) of the rat pancreatic adenocarcinoma line BSp73ASML (ASMLwt). As EpCAM associates with Claudin-7, an ASML-Claudin-7-knockdown (ASML-cld7kd) was included to differentiate between EpC- and EpC-cld7-mediated effects. The metastatic capacity of ASML-EpCkd and more pronounced ASML-cld7kd cells is strikingly reduced. EpC-associated cld7 interferes with EpC-mediated cell–cell adhesion and supports migration. This requires cld7 phosphorylation and formation of an EpC-cld7-tetraspanin-alpha6beta4 complex in glycolipid-enriched membrane domains (GEM), where cld7 associates via the tetraspanin-alpha6beta4 complex with phosphorylated ezrin. The association of cld7 with alpha6beta4 and cytoskeleton strongly stimulates tumor cell migration. However, EpC does not actively contribute. Instead, GEM-located cld7 associates with presenilin-2, which facilitates EpC cleavage and thereby tumor cell proliferation. Finally, the EpC-cld7 complex promotes drug resistance. Both EpC and cld7 support MAPK and JNK activation, such that in ASML-EpCkd and ASML-cld7kd cells an undue expansion of proapoptotic molecules is observed. Only cld7 promotes activation of the PI3K/Akt pathway by a strong downregulation of Pten. Accordingly, cisplatin treatment prolongs the survival time of ASML-cld7kd-bearing rats. Taken together, cld7 supports tumorigenic features of EpC by provoking EpC cleavage and thereby its cotranscription factor activity. On the other hand, only cld7 is directly engaged in motility and apoptosis resistance. Thus, at least in concern of migrating CIC, it is cld7 that acts as a CIC biomarker.
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Claudin-7 regulates EpCAM-mediated functions in tumor progression.
Molecular cancer research : MCR, 2009Co-Authors: Tobias Nübel, Markus Ladwein, Lutz Langbein, Julia Preobraschenski, Hüseyin Tuncay, Tobias Weiss, Sebastian Kuhn, Margot ZollerAbstract:EpCAM has been described as a therapeutically relevant tumor marker. We noted an interaction between EpCAM and the tight junction protein Claudin-7 and here explored the nature of this interaction and its effect on EpCAM-mediated functions. The interaction between EpCAM and Claudin-7 was defined in HEK293 cells transfected with rat Claudin-7 and EpCAM cDNA. Deletions of the epidermal growth factor-like and the thyroglobin repeat domains of EpCAM or the cytoplasmic domain of EpCAM or Claudin-7 did not prevent the EpCAM-Claudin-7 association. A chimeric EpCAM molecule with an exchange of the cytoplasmic and transmembrane domains and an EpCAM molecule with point mutations in an AxxxG motif in the transmembrane region do not associate with Claudin-7. HEK cells and the rat pancreatic tumor line BSp73AS, transfected with (mutated) EpCAM and Claudin-7 cDNA, revealed that the association of both molecules severely alters the functional activity of EpCAM. Claudin-7-associated EpCAM is recruited into tetraspanin-enriched membrane microdomains (TEM). The TEM-located Claudin-7-EpCAM complex supports proliferation accompanied by sustained extracellular signal-regulated kinase-1/2 phosphorylation, up-regulation of antiapoptotic proteins, and drug resistance, but not EpCAM-mediated cell-cell adhesion. Enhanced motility may be supported by colocalization of Claudin-7 with actin bundles, which is only seen in EpCAM-Claudin-7-expressing cells. The EpCAM-Claudin-7 complex strongly promotes tumorigenicity, accelerates tumor growth, and supports ascites production and thymic metastasis formation. High expression of the tumor marker EpCAM is frequently associated with poor prognosis, which could well rely on the EpCAM-Claudin-7 association that prohibits EpCAM-mediated cell-cell adhesion but promotes migration, proliferation, apoptosis resistance, and tumorigenicity.
Yan-hua Chen - One of the best experts on this subject based on the ideXlab platform.
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Claudin-7 modulates cell-matrix adhesion that controls cell migration, invasion and attachment of human HCC827 lung cancer cells
Oncology letters, 2019Co-Authors: Hyung Kim, Yan-hua ChenAbstract:Claudins are a family of tight junction proteins, and serve important roles in epithelial barrier, selective ion transports and cancer metastasis. Although the exact role of Claudin-7 in human lung cancer has not been completely elucidated, recent clinical studies have demonstrated that Claudin-7 is associated with the survival of patients with lung cancer. Our previous studies have demonstrated that Claudin-7 forms a protein complex with integrin β1 in human lung cancer cells. The knockdown (KD) of Claudin-7 by short hairpin RNA (shRNA) reduced integrin β1 expression and increased the cell proliferative rate, whereas Claudin-7 re-expression in the KD cells decreased the cell proliferation. It is unknown as to whether Claudin-7 and integrin β1 regulate cell proliferation and invasion synergistically or independently. In the present study, it was observed that ectopic expression of integrin β1 in Claudin-7 KD lung cancer cells did not reduce the cell proliferation. However, integrin β1-transfected cells migrated more effectively in wound healing and cell invasion assays and were more adhesive in a cell attachment assay when compared with those of Claudin-7 KD cells. This indicates that Claudin-7 controls cell proliferation, while cell attachment and motility were regulated partially through integrin β1. Additionally, Claudin-7 overexpression in Claudin-7 KD cells resulted in an improved ability to attach to the surface of cell culture plates and a higher expression of focal adhesion proteins when compared with Claudin-7 non-KD control cells, which supports the role of Claudin-7 in cell adhesion and motility. Taken together, these data suggest that Claudin-7 regulates cell motility through integrin β1, providing additional insight into the roles of Claudins in carcinogenesis and cancer cell metastasis.
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Severe Intestinal Inflammation in the Small Intestine of Mice Induced by Controllable Deletion of Claudin-7.
Digestive diseases and sciences, 2018Co-Authors: Kun Wang, Yan-hua Chen, Xiaonan Wang, Hui Yang, Tiaosi Xing, Hong GaoAbstract:Background As a potential tumor suppressor gene, Claudin-7 (Cldn7), which is a component of tight junctions, may play an important role in colorectal cancer occurrence and development.
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Immunohistochemical quantification of expression of a tight junction protein, Claudin-7, in human lung cancer samples using digital image analysis method.
Computer methods and programs in biomedicine, 2017Co-Authors: Yi Liu, Yan-hua Chen, Hongping Yin, Haiying Yuan, Liyun Shi, Dan Chen, Bin XieAbstract:Abstract Background and objectives Tight junction proteins are correlated with cancer development. As the pivotal proteins in epithelial cells, altered expression and distribution of different Claudins have been reported in a wide variety of human malignancies. We have previously reported that Claudin-7 was strongly expressed in benign bronchial epithelial cells at the cell-cell junction while expression of Claudin-7 was either altered with discontinued weak expression or completely absent in lung cancers. Based on these results, we continued working on the expression pattern of Claudin-7 and its relationship with lung cancer development. We herein proposed a new Digital Image Classification, Fragmentation index, Morphological analysis (DICFM) method for differentiating the normal lung tissues and lung cancer tissues based on the Claudin-7 immunohistochemical staining. Methods Seventy-seven lung cancer samples were obtained from the Second Affiliated Hospital of Zhejiang University and Claudin-7 immunohistochemical staining was performed. Based on C++ and Open Source Computer Vision Library (OpenCV, version 2.4.4), the DICFM processing module was developed. Intensity and fragmentation of Claudin-7 expression, as well as the morphological parameters of nuclei were calculated. Evaluation of results was performed using Receiver Operator Characteristic (ROC) analysis. Results Agreement between these computational results and the results obtained by two pathologists was demonstrated. The intensity of Claudin-7 expression was significantly decreased while the fragmentation was significantly increased in the lung cancer tissues compared to the normal lung tissues and the intensity was strongly positively associated with the differentiation of lung cancer cells. Moreover, the perimeters of the nuclei of lung cancer cells were significantly greater than that of the normal lung cells, while the parameters of area and circularity revealed no statistical significance. Conclusions Taken together, our DICFM approach may be applied as an appropriate approach to quantify the immunohistochemical staining of Claudin-7 on the cell membrane and Claudin-7 may serve as a marker for identification of lung cancer.
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A non-tight junction function of Claudin-7-Interaction with integrin signaling in suppressing lung cancer cell proliferation and detachment.
Molecular cancer, 2015Co-Authors: Hyung Kim, Lei Ding, Randall H. Renegar, Junming Fan, Kathryn M. Verbanac, Yan-hua ChenAbstract:Background Claudins are a family of tight junction (TJ) membrane proteins involved in a broad spectrum of human diseases including cancer. Claudin-7 is a unique TJ membrane protein in that it has a strong basolateral membrane distribution in epithelial cells and in tissues. Therefore, this study aims to investigate the functional significance of this non-TJ localization of Claudin-7 in human lung cancer cells.
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Claudin-7, -16, and -19 during mouse kidney development.
Tissue barriers, 2014Co-Authors: Halim Khairallah, Yan-hua Chen, Jasmine El Andalousi, Annie Simard, Nicholas Haddad, Jianghui Hou, Aimee K. Ryan, Indra R. GuptaAbstract:Members of the Claudin family of tight junction proteins are critical for establishing epithelial barriers and for the regulation of paracellular transport. To understand their roles during kidney development, we first performed RT-PCR analyses and determined that 23 Claudin family members were expressed in embryonic day (E) 13.5 mouse kidneys. Based on their developmental expression and phenotypes in mouse models, we hypothesized that 3 Claudin members could affect nephron formation during kidney development. Using whole mount in situ hybridization and immunohistochemistry, we demonstrated that Claudin-7 (Cldn7) was expressed in the nephric duct, the emerging ureteric bud, and in tubules derived from ureteric bud branching morphogenesis. In contrast, Claudin-16 (Cldn16) and Claudin-19 (Cldn19) were expressed at later stages of kidney development in immature renal tubules that become the Loop of Henle. To determine if a loss of these Claudins would perturb kidney development, we examined newborn kidneys from mutant mouse models lacking Cldn7 or Cldn16. In both models, we noted no evidence for any congenital renal malformation and quantification of nephron number did not reveal a decrease in nephron number when compared to wildtype littermates. In summary, Cldn7, Cldn16, and Cldn19 are expressed in different epithelial lineages during kidney development. Mice lacking Cldn7 or Cldn16 do not have defects in de novo nephron formation, and this suggests that these Claudins primarily function to regulate paracellular transport in the mature nephron.
Lei Ding - One of the best experts on this subject based on the ideXlab platform.
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Non-tight junction-related function of Claudin-7 in interacting with integrinβ1 to suppress colorectal cancer cell proliferation and migration.
Cancer management and research, 2019Co-Authors: Kun Wang, Yuhan Ding, Lei DingAbstract:Purpose We conducted a preliminarily exploration of the role and possible mechanism of the non-tight junction-related function of Claudin-7 in the occurrence and development of colorectal cancer. Methods We selected the colorectal cancer cell line HCT116, constructed a stably transfected Claudin-7 knockdown cell line via RNAi and lentiviral infection, and determined the Claudin-7 knockdown efficiency. We assessed the biological behavior changes (cell viability, apoptosis, and migration) in the stably transfected HCT116 cells and observed structural changes in the tight junction by transmission electron microscopy. We used a subcutaneous tumor formation model to assess the tumorigenicity of HCT116 cells after Claudin-7 knockdown. We assessed the expression and localization of integrinβ1 in the stably transfected cell line by immunofluorescence staining and investigated the interaction between integrinβ1 and Claudin-7 by co-immunoprecipitation. Results After the knockdown of Claudin-7 the expression, the viability and migration ability of HCT116 cells increased and apoptosis decreased. Transmission electron microscopy indicated that the intercellular tight junction structure did not change substantially. Furthermore, the tumor growth in nude mice was enhanced. Immunofluorescence staining showed that integrinβ1 and Claudin-7 were co-expressed and co-localized on the cell membrane, and immunoprecipitation suggested that Claudin-7 interacts with integrinβ1. Conclusion Claudin-7 may inhibit the proliferation and migration of tumor cells by interacting with integrinβ1, subsequently participating in the development of colorectal cancer.
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Claudin-7 gene knockout causes destruction of intestinal structure and animal death in mice
World journal of gastroenterology, 2019Co-Authors: Kun Wang, Yuhan Ding, Lei DingAbstract:Background Claudin-7, one of the important components of cellular tight junctions, is currently considered to be expressed abnormally in colorectal inflammation and colorectal cancer. However, there is currently no effective animal model to study its specific mechanism. Therefore, we constructed three lines of Claudin-7 knockout mice using the Cre/LoxP system. Aim To determine the function of the tumor suppressor gene Claudin-7 by generating three lines of Claudin-7 gene knockout mice. Methods We crossed Claudin-7-floxed mice with CMV-Cre, vil1-Cre, and villin-CreERT2 transgenic mice, and the offspring were self-crossed to obtain conventional Claudin-7 knockout mice, conditional (intestinal specific) Claudin-7 knockout mice, and inducible conditional Claudin-7 knockout mice. Intraperitoneal injection of tamoxifen into the inducible conditional Claudin-7 knockout mice can induce the knockout of Claudin-7. PCR and agarose gel electrophoresis were used to identify mouse genotypes, and Western blot was used to confirm the knockout of Claudin-7. The mental state, body length, and survival time of these mice were observed. The dying mice were sacrificed, and hematoxylin-eosin (HE) staining and immunohistochemical staining were performed to observe changes in intestinal structure and proliferation markers. Results We generated Claudin-7-floxed mice and three lines of Claudin-7 gene knockout mice using the Cre/LoxP system successfully. Conventional and intestinal specific Claudin-7 knockout mice were stunted and died during the perinatal period, and intestinal HE staining in these mice revealed mucosal gland structure disappearance and connective tissue hyperplasia with extensive inflammatory cell infiltration. The inducible conditional Claudin-7 knockout mice had a normal phenotype at birth, but after the induction with tamoxifen, they exhibited a dying state. Intestinal HE staining showed significant inflammatory cell infiltration, and atypical hyperplasia and adenoma were also observed. Intestinal immunohistochemistry analysis showed abnormal expression and distribution of Ki67, and the normal intestinal proliferation balance was disrupted. The intestinal crypt size in inducible conditional Claudin-7 knockout mice was increased compared with control mice (small intestine: 54.1 ± 2.96 vs 38.4 ± 1.63; large intestine: 44.7 ± 1.93 vs 27.4 ± 0.60; P Conclusion The knockout of Claudin-7 in vivo causes extensive inflammation, atypical hyperplasia, and adenoma in intestinal tissue as well as animal death in mice. Claudin-7 may act as a tumor suppressor gene in the development of colorectal cancer.
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Expression and Clinical Significance of Claudin-7 in Patients With Colorectal Cancer:
Technology in Cancer Research & Treatment, 2018Co-Authors: Xiaonan Wang, Kun Wang, Lei DingAbstract:Background and Objective:Claudin-7 is a component of tight junctions and plays important roles in maintaining cell polarity and tightly connecting the barriers between cells. Abnormal Claudin-7 pro...
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Claudin-7 downregulation induces metastasis and invasion in colorectal cancer via the promotion of epithelial-mesenchymal transition.
Biochemical and biophysical research communications, 2018Co-Authors: Kun Wang, Yuhan Ding, Lei DingAbstract:Abstract The dysregulation of the tight junctions (TJs) protein Claudin-7 is closely related to the development and metastasis of colorectal cancer (CRC). The aim of this study was to investigate the expression of Claudin-7 and characterize the relationship between Claudin-7 expression and epithelial-mesenchymal transition (EMT) in CRC. In this study, the expression of Claudin-7, E-cadherin, vimentin and snail-1 was detected by immunohistochemistry (IHC) in a set of 80 CRC specimens comprising 20 specimens each of well-differentiated, moderately differentiated, poorly differentiated and liver metastases tissues. The correlation between Claudin-7 and EMT-related proteins in the stably transfected Claudin-7 knockdown HCT116 cell line was analyzed by IHC, immunofluorescence (IF), Western blotting (WB) and nude mouse xenograft models. The results revealed that the expression of Claudin-7 was downregulated as CRC tissue differentiation grade decreased, and that low Claudin-7 expression corresponded to the downregulation of E-cadherin (r = 0.725, p
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Emerging clinical significance of Claudin-7 in colorectal cancer: a review.
Cancer management and research, 2018Co-Authors: Kun Wang, Lei DingAbstract:Tight junctions (TJs) play an important role in maintaining cell polarity and regulating cell permeability. In recent years, many studies have shown that TJ proteins, especially Claudin-7, are closely related to inflammation and the development of various malignant tumors. Claudin-7 plays a significant role in maintaining the physiological functions and pathological conditions of the TJ barrier. The dysregulation of Claudin-7 plays a tumor suppressor role or conversely has carcinogenic effects in different target tissues or cells, but the exact underlying mechanism is still unclear. In this review, we will summarize the expression pattern of Claudin-7 in tumors, focusing on the expression and regulation of Claudin-7 in colorectal cancer and discussing the correlation between Claudin-7 and invasion, metastasis and epithelial-mesenchymal transition (EMT) in colorectal cancer. The construction of Cldn7-/- mice and conventional Claudin-7 knockout mouse models has helped determine the mechanisms by which Claudin-7 promotes tumorigenesis. Elucidation of the expression and subcellular localization of Claudin-7 under pathological conditions will help develop Claudin-7 as a useful biomarker for detecting and diagnosing cancer, and thus may help combat the occurrence, development, and invasion of cancers.
Andrew N. Young - One of the best experts on this subject based on the ideXlab platform.
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Claudin 7 and Claudin 8 immunohistochemical markers for the differential diagnosis of chromophobe renal cell carcinoma and renal oncocytoma
Human Pathology, 2009Co-Authors: Adeboye O. Osunkoya, Diane Lawson, Maria M Picken, Mahul B. Amin, Cynthia Cohen, Andrew N. YoungAbstract:Summary Claudin-7 and Claudin-8 code for tight junction proteins expressed in distal nephron epithelium. In a recent oligonucleotide microarray study, we identified Claudin-7 and Claudin-8 as candidate markers to distinguish chromophobe renal cell carcinoma from other renal tumors, including oncocytoma. Distinction of these lesions can be difficult by light microscopy but is clinically important because chromophobe renal cell carcinoma has malignant biological potential, whereas renal oncocytoma is benign. Claudin-7 and Claudin-8 expression was studied by immunohistochemistry in 11 chromophobe renal cell carcinomas and 17 oncocytomas using formalin-fixed paraffin-embedded tissue sections of tumor with adjacent nonneoplastic kidney. Steam antigen retrieval was performed before immunohistochemistry. Specificity was verified by negative control reactions without primary antibody and appropriate membranous staining patterns in positive control tissues (colon carcinoma and adjacent nonneoplastic kidney). Claudin-7 protein was expressed in a membranous pattern in 10 of 11 chromophobe renal cell carcinomas and 4 of 17 oncocytomas ( P P
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Claudin-7 and Claudin-8: immunohistochemical markers for the differential diagnosis of chromophobe renal cell carcinoma and renal oncocytoma.
Human pathology, 2008Co-Authors: Adeboye O. Osunkoya, Diane Lawson, Maria M Picken, Mahul B. Amin, Cynthia Cohen, Andrew N. YoungAbstract:Claudin-7 and Claudin-8 code for tight junction proteins expressed in distal nephron epithelium. In a recent oligonucleotide microarray study, we identified Claudin-7 and Claudin-8 as candidate markers to distinguish chromophobe renal cell carcinoma from other renal tumors, including oncocytoma. Distinction of these lesions can be difficult by light microscopy but is clinically important because chromophobe renal cell carcinoma has malignant biological potential, whereas renal oncocytoma is benign. Claudin-7 and Claudin-8 expression was studied by immunohistochemistry in 11 chromophobe renal cell carcinomas and 17 oncocytomas using formalin-fixed paraffin-embedded tissue sections of tumor with adjacent nonneoplastic kidney. Steam antigen retrieval was performed before immunohistochemistry. Specificity was verified by negative control reactions without primary antibody and appropriate membranous staining patterns in positive control tissues (colon carcinoma and adjacent nonneoplastic kidney). Claudin-7 protein was expressed in a membranous pattern in 10 of 11 chromophobe renal cell carcinomas and 4 of 17 oncocytomas (P < .01). Claudin-8 was expressed in multiple patterns: In oncocytoma, 11 of 17 cases showed cytoplasmic, 4 of 17 membranous, and 2 of 17 negative reactions. In chromophobe renal cell carcinoma, 0 of 11 cases showed cytoplasmic, 3 of 11 membranous, and 8 of 11 negative reactions (P < .01). The immunohistochemical pattern of membranous Claudin-7 and negative Claudin-8 was seen in 7 of 11 chromophobe renal cell carcinomas and 1 of 17 oncocytomas (63% sensitivity, 84% specificity, 88% positive predictive value for chromophobe renal cell carcinoma). Negative Claudin-7 and cytoplasmic Claudin-8 were observed in 10 of 17 oncocytomas and 0 of 11 chromophobe renal cell carcinomas (59% sensitivity, 100% specificity and positive predictive value for oncocytoma). The distal nephron proteins Claudin-7 and Claudin-8 have potential use as immunohistochemical biomarkers in the differential diagnosis of chromophobe renal cell carcinoma and oncocytoma. Expression of Claudin-7 and Claudin-8 may reflect the relationship of chromophobe renal cell carcinoma and oncocytoma to intercalated cells of the cortical collecting duct. It may be necessary to identify additional biomarkers to include with Claudin-7 and Claudin-8 in a larger immunohistochemical panel to improve diagnostic sensitivity and specificity.
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Claudin-7 immunohistochemistry in renal tumors: a candidate marker for chromophobe renal cell carcinoma identified by gene expression profiling.
Archives of pathology & laboratory medicine, 2007Co-Authors: Christopher D. Hornsby, Diane Lawson, Maria M Picken, Mahul B. Amin, Cynthia Cohen, Qiqin Yin-goen, Andrew N. YoungAbstract:Abstract Context.—The differential diagnosis of eosinophilic renal tumors can be difficult by light microscopy. In particular, chromophobe renal cell carcinoma (RCC) is difficult to distinguish from oncocytoma. This differential diagnosis is important because chromophobe RCC is malignant, whereas oncocytoma is benign. Furthermore, chromophobe RCC has distinct malignant potential and prognosis compared with eosinophilic variants of other RCC subtypes. Immunohistochemistry is useful for distinguishing chromophobe RCC from other subtypes of renal carcinoma, but no expression marker reliably separates chromophobe RCC from oncocytoma. Objective.—In a previous gene expression microarray analysis of renal tumor subtypes, we found the distal nephron markers Claudin-7 and Claudin-8 to be overexpressed in chromophobe RCC versus oncocytoma and other tumor subtypes. We have confirmed similar findings in independent microarray data and validated differential Claudin-7 protein expression by immunohistochemistry. Design...
Florian Thuma - One of the best experts on this subject based on the ideXlab platform.
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The importance of Claudin-7 palmitoylation on membrane subdomain localization and metastasis-promoting activities
Cell communication and signaling : CCS, 2015Co-Authors: Sarah Heiler, Margot Zoller, Florian ThumaAbstract:Background Claudin-7 (cld7), a tight junction (TJ) component, is also found basolaterally and in the cytoplasm. Basolaterally located cld7 is enriched in glycolipid-enriched membrane domains (GEM), where it associates with EpCAM (EpC). The conditions driving cld7 out of TJ into GEM, which is associated with a striking change in function, were not defined. Thus, we asked whether cld7 serines or palmitoylation affect cld7 location and protein, particularly EpCAM, associations.
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Claudin-7 promotes the epithelial-mesenchymal transition in human colorectal cancer.
Oncotarget, 2014Co-Authors: Rahel Philip, Margot Zoller, Sarah Heiler, Markus W. Büchler, Florian ThumaAbstract:// Rahel Philip 1 , Sarah Heiler 1 , Wei Mu 1 , Markus W. Buchler 2 , Margot Zoller 1 and Florian Thuma 1 1 Department of Tumor Cell Biology, University Hospital of Surgery, Heidelberg 2 University Hospital of General Surgery, Heidelberg Correspondence: Florian Thuma, email: // Margot Zoller, email: // Keywords : Colorectal cancer, Claudin 7, EpCAM, cancer initiating cells, metastasis Received : September 15, 2014 Accepted : December 02, 2014 Published : December 03, 2014 Abstract In colorectal cancer (CoCa) EpCAM is frequently associated with Claudin-7. There is evidence that tumor-promoting EpCAM activities are modulated by the association with Claudin-7. To support this hypothesis, Claudin-7 was knocked-down (kd) in HT29 and SW948 cells. HT29-cld7 kd and SW948-cld7 kd cells display decreased anchorage-independent growth and the capacity for holoclone-, respectively, sphere-formation is reduced. Tumor growth is delayed and cld7 kd cells poorly metastasize. In line with this, migratory and invasive potential of cld7 kd clones is strongly impaired, migration being inhibited by anti-CD49c, but not anti-EpCAM, although motility is reduced in EpCAM siRNA-treated cells. This is due to Claudin-7 recruiting EpCAM in glycolipid-enriched membrane fractions towards Claudin-7-associated TACE and presenilin2, which cleave EpCAM. The cleaved intracellular domain, EpIC, promotes epithelial-mesenchymal transition (EMT)-associated transcription factor expression, which together with fibronectin and vimentin are reduced in Claudin-7 kd cells. But, uptake of HT29 wt and SW948 wt exosomes by the Claudin-7 kd lines sufficed for transcription factor upregulation and for restoring motility. Thus, Claudin-7 contributes to motility and invasion and is required for recruiting EpCAM towards TACE/presenilin2. EpIC generation further supports motility by promoting a shift towards EMT. Notably, EMT features of cld7-competent metastatic CoCa cells can be transferred via exosomes to poorly metastatic cells.
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epcam associated Claudin 7 supports lymphatic spread and drug resistance in rat pancreatic cancer
International Journal of Cancer, 2013Co-Authors: Florian Thuma, Margot ZollerAbstract:Pancreatic cancer has a dismal prognosis because of early metastatic spread, a suggested feature of cancer-initiating cells (CIC). To control for a functional contribution of the pancreatic CIC-marker EpCAM, we explored metastasis formation by a stable EpCAM-knockdown (ASML-EpCkd) of the rat pancreatic adenocarcinoma line BSp73ASML (ASMLwt). As EpCAM associates with Claudin-7, an ASML-Claudin-7-knockdown (ASML-cld7kd) was included to differentiate between EpC- and EpC-cld7-mediated effects. The metastatic capacity of ASML-EpCkd and more pronounced ASML-cld7kd cells is strikingly reduced. EpC-associated cld7 interferes with EpC-mediated cell–cell adhesion and supports migration. This requires cld7 phosphorylation and formation of an EpC-cld7-tetraspanin-alpha6beta4 complex in glycolipid-enriched membrane domains (GEM), where cld7 associates via the tetraspanin-alpha6beta4 complex with phosphorylated ezrin. The association of cld7 with alpha6beta4 and cytoskeleton strongly stimulates tumor cell migration. However, EpC does not actively contribute. Instead, GEM-located cld7 associates with presenilin-2, which facilitates EpC cleavage and thereby tumor cell proliferation. Finally, the EpC-cld7 complex promotes drug resistance. Both EpC and cld7 support MAPK and JNK activation, such that in ASML-EpCkd and ASML-cld7kd cells an undue expansion of proapoptotic molecules is observed. Only cld7 promotes activation of the PI3K/Akt pathway by a strong downregulation of Pten. Accordingly, cisplatin treatment prolongs the survival time of ASML-cld7kd-bearing rats. Taken together, cld7 supports tumorigenic features of EpC by provoking EpC cleavage and thereby its cotranscription factor activity. On the other hand, only cld7 is directly engaged in motility and apoptosis resistance. Thus, at least in concern of migrating CIC, it is cld7 that acts as a CIC biomarker.
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EpCAM‐associated Claudin‐7 supports lymphatic spread and drug resistance in rat pancreatic cancer
International journal of cancer, 2013Co-Authors: Florian Thuma, Margot ZollerAbstract:Pancreatic cancer has a dismal prognosis because of early metastatic spread, a suggested feature of cancer-initiating cells (CIC). To control for a functional contribution of the pancreatic CIC-marker EpCAM, we explored metastasis formation by a stable EpCAM-knockdown (ASML-EpCkd) of the rat pancreatic adenocarcinoma line BSp73ASML (ASMLwt). As EpCAM associates with Claudin-7, an ASML-Claudin-7-knockdown (ASML-cld7kd) was included to differentiate between EpC- and EpC-cld7-mediated effects. The metastatic capacity of ASML-EpCkd and more pronounced ASML-cld7kd cells is strikingly reduced. EpC-associated cld7 interferes with EpC-mediated cell–cell adhesion and supports migration. This requires cld7 phosphorylation and formation of an EpC-cld7-tetraspanin-alpha6beta4 complex in glycolipid-enriched membrane domains (GEM), where cld7 associates via the tetraspanin-alpha6beta4 complex with phosphorylated ezrin. The association of cld7 with alpha6beta4 and cytoskeleton strongly stimulates tumor cell migration. However, EpC does not actively contribute. Instead, GEM-located cld7 associates with presenilin-2, which facilitates EpC cleavage and thereby tumor cell proliferation. Finally, the EpC-cld7 complex promotes drug resistance. Both EpC and cld7 support MAPK and JNK activation, such that in ASML-EpCkd and ASML-cld7kd cells an undue expansion of proapoptotic molecules is observed. Only cld7 promotes activation of the PI3K/Akt pathway by a strong downregulation of Pten. Accordingly, cisplatin treatment prolongs the survival time of ASML-cld7kd-bearing rats. Taken together, cld7 supports tumorigenic features of EpC by provoking EpC cleavage and thereby its cotranscription factor activity. On the other hand, only cld7 is directly engaged in motility and apoptosis resistance. Thus, at least in concern of migrating CIC, it is cld7 that acts as a CIC biomarker.