scholarly journals CLDN6: From Traditional Barrier Function to Emerging Roles in Cancers

2021 ◽  
Vol 22 (24) ◽  
pp. 13416
Author(s):  
Huinan Qu ◽  
Qiu Jin ◽  
Chengshi Quan

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.

2019 ◽  
Author(s):  
Shannon D McClintock ◽  
Michael K Dame ◽  
Aliah Richter ◽  
Durga Attili ◽  
Sabrina S Silvestri ◽  
...  

AbstractBackground and aimsHuman colonoid cultures maintained under low-calcium (0.25 mM) conditions undergo differentiation spontaneously and, concomitantly, express a high level of tight junction proteins, but not desmosomal proteins. When calcium is included to a final concentration of 1.5 – 3.0 mM (provided either as a single agent or as a combination of calcium and minerals), there is little change in tight junction proteins but a strong up-regulation of desmosomal proteins and an increase in desmosome formation. The aim of this study was to assess functional consequences of the differences in calcium-mediated barrier protein expression.MethodsHuman colonoid-derived epithelial monolayers were interrogated in transwell culture under low- or high-calcium conditions. Ion permeability and monolayer integrity were assessed by measuring trans-epithelial electrical resistance (TEER) across the confluent monolayer. Colonoid cohesiveness was assessed in parallel.ResultsTEER values were high in the low-calcium environment and increased only modestly in response to calcium. In contrast, colonoid cohesiveness increased substantially with calcium supplementation. In both assays, the response to Aquamin was greater than the response to calcium alone. However, differences between interventions were small and only compared to the 0.25 mM calcium were they statistically significant. Consistent with these findings, occludin expression (a measure of tight junctions) was high at 0.25 mM calcium and did not increase with supplementation. Cadherin-17 and desmoglein-2 were weakly-expressed under low calcium conditions but increased with intervention.ConclusionsThese findings indicate that low ambient calcium levels are sufficient to support formation of a permeability barrier in the colonic epithelium. Higher calcium levels are necessary to promote tissue cohesion and enhance barrier function. These findings may help explain how an adequate daily intake of calcium contributes to colonic health by improving barrier function, even though there is little change in colonic histological features over a wide range of calcium intake levels.


Planta Medica ◽  
2008 ◽  
Vol 74 (09) ◽  
Author(s):  
HY Jeon ◽  
JK Kim ◽  
JE Lee ◽  
WG Kim ◽  
SJ Lee

Author(s):  
Han-Wen Chen ◽  
Xiao-Xia Zhang ◽  
Zhu-Ding Peng ◽  
Zu-Min Xing ◽  
Yi-Wen Zhang ◽  
...  

AbstractTreatment of bone cancer pain (BCP) caused by bone metastasis in advanced cancers remains a challenge in clinical oncology, and the underlying mechanisms of BCP are poorly understood. This study aimed to investigate the pathogenic roles of circular RNAs (circRNAs) in regulating cancer cell proliferation and BCP development. Eight differentially expressed circRNAs in the rat spinal cord were validated by agarose gel electrophoresis and Sanger sequencing. Expression of circRNAs and mRNAs was detected by quantitative RT-PCR. MTS assay and flow cytometry were performed to analyze cell proliferation and apoptosis, respectively. Differentially expressed mRNA profiles were characterized by deep RNA sequencing, hierarchical clustering, and functional categorization. The interactions among circRNAs, microRNAs (miRNAs), and mRNAs were predicted using TargetScan. Additionally, western blot was performed to determine the protein levels of Pax8, Isg15, and Cxcl10. Multiple circRNAs were differentially expressed in the spinal cords of BCP model rats; of these, circSlc7a11 showed the greatest increase in expression. The overexpression of circSlc7a11 significantly promoted cell proliferation and repressed apoptosis of LLC-WRC 256 and UMR-106 cells, whereas circSlc7a11 silencing produced the opposite effects. Altered expression of circSlc7a11 also induced substantial changes in the mRNA expression profiles of LLC-WRC 256 cells; these changes were linked to multiple apoptotic processes and signaling pathways, such as the chemokine signaling pathway, and formed a complex circRNA/miRNA/mRNA network. Additionally, Pax8, Isg15, and Cxc110 protein level in LLC-WRC 256 cells was consistent with the mRNA results. The circRNA circSlc7a11 regulates rat BCP development by modulating LLC-WRC 256 cell proliferation and apoptosis through multiple-signaling mechanisms.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zehua Zhang ◽  
Fei Dai ◽  
Fei Luo ◽  
Wenjie Wu ◽  
Shuai Zhang ◽  
...  

AbstractOsteosarcoma is a malignant osteoblastic tumor that can gravely endanger the lives and health of children and adolescents. Therefore, there is an urgent need to explore new biomarkers for osteosarcoma and determine new targeted therapies to improve the efficacy of osteosarcoma treatment. Diaphanous related formin 3 (DIAPH3) promotes tumorigenesis in hepatocellular carcinoma and lung adenocarcinoma, suggesting that DIAPH3 may be a target for tumor therapy. To date, there have been no reports on the function of DIAPH3 in osteosarcoma. DIAPH3 protein expression in osteosarcoma tissues and healthy bone tissues adjacent to cancer cells was examined by immunohistochemical staining. DIAPH3 mRNA expression correlates with overall survival and reduced disease-free survival. DIAPH3 protein is upregulated in osteosarcoma tissues, and its expression is significantly associated with tumor size, tumor stage, node metastasis, and distant metastasis. Functional in vitro experiments revealed that DIAPH3 knockdown suppressed cell proliferation and suppressed cell migration and invasion of osteosarcoma cell lines MG-63 and HOS. Functional experiments demonstrated that DIAPH3 knockdown inhibited subcutaneous tumor growth and lung metastasis in vivo. In conclusion, DIAPH3 expression can predict the clinical outcome of osteosarcoma. In addition, DIAPH3 is involved in the proliferation and metastasis of osteosarcoma, and as such, DIAPH3 may be a potential therapeutic target for osteosarcoma.


2021 ◽  
Vol 26 (1) ◽  
Author(s):  
Qiudan Chen ◽  
Weifeng Wang ◽  
Shuying Chen ◽  
Xiaotong Chen ◽  
Yong Lin

AbstractRecently, pivotal functions of miRNAs in regulating common tumorigenic processes and manipulating signaling pathways in brain tumors have been recognized; notably, miR‐29a is closely associated with p53 signaling, contributing to the development of glioma. However, the molecular mechanism of the interaction between miR-29a and p53 signaling is still to be revealed. Herein, a total of 30 glioma tissues and 10 non-cancerous tissues were used to investigate the expression of miR‐29a. CCK-8 assay and Transwell assay were applied to identify the effects of miR-29a altered expression on the malignant biological behaviors of glioma cells in vitro, including proliferation, apoptosis, migration and invasion. A dual-luciferase reporter assay was used to further validate the regulatory effect of p53 or miR-29a on miR-29a or MDM2, respectively, at the transcriptional level. The results showed that miR-29a expression negatively correlated with tumor grade of human gliomas; at the same time it inhibited cell proliferation, migration, and invasion and promoted apoptosis of glioma cells in vitro. Mechanistically, miR-29a expression was induced by p53, leading to aberrant expression of MDM2 targeted by miR-29a, and finally imbalanced the activity of the p53-miR-29a-MDM2 feedback loop. Moreover, miR-29a regulating p53/MDM2 signaling sensitized the response of glioma cells to temozolomide treatment. Altogether, the study demonstrated a potential molecular mechanism in the tumorigenesis of glioma, while offering a possible target for treating human glioma in the future.


2021 ◽  
Vol 9 (1) ◽  
pp. 11
Author(s):  
Clinton Rice ◽  
Oindrila De ◽  
Haifa Alhadyian ◽  
Sonia Hall ◽  
Robert E. Ward

The septate junction (SJ) provides an occluding function for epithelial tissues in invertebrate organisms. This ability to seal the paracellular route between cells allows internal tissues to create unique compartments for organ function and endows the epidermis with a barrier function to restrict the passage of pathogens. Over the past twenty-five years, numerous investigators have identified more than 30 proteins that are required for the formation or maintenance of the SJs in Drosophila melanogaster, and have determined many of the steps involved in the biogenesis of the junction. Along the way, it has become clear that SJ proteins are also required for a number of developmental events that occur throughout the life of the organism. Many of these developmental events occur prior to the formation of the occluding junction, suggesting that SJ proteins possess non-occluding functions. In this review, we will describe the composition of SJs, taking note of which proteins are core components of the junction versus resident or accessory proteins, and the steps involved in the biogenesis of the junction. We will then elaborate on the functions that core SJ proteins likely play outside of their role in forming the occluding junction and describe studies that provide some cell biological perspectives that are beginning to provide mechanistic understanding of how these proteins function in developmental contexts.


Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1820
Author(s):  
Chengcheng Hao ◽  
Yuxin Cui ◽  
Jane Lane ◽  
Shuqin Jia ◽  
Jiafu Ji ◽  
...  

Background: Osteopontin (OPN) splice variants are identified as predictors of tumour progression and therapeutic resistance in certain types of solid tumours. However, their roles in gastric cancer (GC) remain poorly characterized. The current study sought to assess the prognostic value of the three OPN splice variants (namely OPN-a, OPN-b, and OPN-c) in gastric cancer and their potential functions within gastric cancer cells. Methods: RNA extraction and reverse transcription were performed using our clinical cohort of gastric carcinomas and matched normal tissues (n = 324 matched pairs). Transcript levels were determined using real-time quantitative PCR. Three OPN splice variants overexpressed cell lines were created from the gastric cancer cell line HGC-27. Subsequently, biological functions, including cell growth, adhesion, migration, and invasion, were studied. The potential effects of OPN isoforms on cisplatin and 5-Fu were evaluated by detecting cellular reactive oxygen species (ROS) levels in the HGC-27-derived cell lines. Results: Compared with normal tissues, the expression levels of three splice variants were all elevated in gastric cancer tissues in an order of OPN-a > OPN-b > OPN-c. The OPN-a level significantly increased with increasing TNM staging and worse clinical outcome. There appeared to be a downregulation for OPN-c in increasing lymph node status (p < 0.05), increasing TNM staging, and poor differentiation. High levels of OPN-a and OPN-b were correlated with short overall survival and disease-free survival of gastric cancer patients. However, the low expression of OPN-c was significantly associated with a poor prognosis. Functional analyses further showed that ectopic expression of OPN-c suppressed in vitro proliferation, adhesiveness, migration, and invasion properties of HGC-27 cells, while the opposite role was seen for OPN-a. Cellular ROS detection indicated that OPN-a and OPN-c significantly promoted ROS production after treatment with 5-Fu comparing to OPN-vector, while only OPN-a markedly induced ROS production after treatment with cisplatin. Conclusion: Our results suggest that OPN splice variants have distinguished potential to predict the prognosis of gastric cancer. Three OPN variants exert distinctive functions in gastric cancer cells. Focusing on specific OPN isoforms could be a novel direction for developing diagnostic and therapeutic approaches in gastric cancer.


Open Medicine ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. 795-804
Author(s):  
Junjie Hang ◽  
Feifei Wei ◽  
Zhiying Yan ◽  
Xianming Zhang ◽  
Kequn Xu ◽  
...  

Abstract Purpose Colon cancer is one of the malignant tumors that threatens human health. miR-510 was demonstrated to play roles in the progression of various cancers; its dysregulation was speculated to be associated with the development of colon cancer. Methods One hundred and thirteen colon cancer patients participated in this research. With the help of RT-qPCR, the expression of miR-510 in collected tissues and cultured cells was analyzed. The association between miR-510 expression level and clinical features and prognosis of patients was evaluated. Moreover, the effects of miR-510 on cell proliferation, migration, and invasion of colon cancer were assessed by CCK8 and Transwell assay. Results miR-510 significantly upregulated in colon cancer tissues and cell lines relative to the adjacent normal tissues and colonic cells. The expression of miR-510 was significantly associated with the TNM stage and poor prognosis of patients, indicating miR-510 was involved in the disease progression and clinical prognosis of colon cancer. Additionally, the upregulation of miR-510 significantly promoted cell proliferation, migration, and invasion of colon cancer, while its knockdown significantly inhibited these cellular processes. SRCIN 1 was the direct target of miR-510 during its promoted effect on the development of colon cancer. Conclusion The upregulation of miR-510 acts as an independent prognostic indicator and a tumor promoter by targeting SRCIN 1 in colon cancer, which provides novel therapeutic strategies for colon cancer.


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