Overexpression of claudin-4 may be involved in endometrial tumorigenesis

Finding the junction between claudins and endometrial carcinoma

Endometrial carcinoma (EC) defines a heterogeneous group of neoplastic diseases originating from the transformation of endometrial cells that constitute the internal lining of the uterus. To date several molecular targets have been analysed to describe the natural course of the disease, claudins being among these. Claudins are the main components of tight junctions (TJs), and their main functions are ascribed to the compartmentalization of tissues and cell-cell communication by means of intracellular ions diffusion: these features are typical of epithelial cells. Their overexpression, mis-localization or loss contribute to the malignancy of EC cells. This review collected all available data regarding the expression, regulation and claudin-related signaling pathways to provide a comprehensive view on the influence of claudin in EC progression. Further, the translational potential of claudin differential expression was explored, indicating that their role in personalized medicine could also contribute to EC therapy besides their employment for diagnosis and prognosis.

IL-22 regulates endometrial regeneration by enhancing tight junctions and orchestrating extracellular matrix

The uterine endometrium uniquely regenerates after menses, postpartum, or after breaks in the uterine layer integrity throughout women’s lives. Direct cell–cell contacts ensured by tight and adherens junctions play an important role in endometrial integrity. Any changes in these junctions can alter the endometrial permeability of the uterus and have an impact on the regeneration of uterine layers. Interleukin 22 (IL-22) is a cytokine that is recognized for its role in epithelial regeneration. Moreover, it is crucial in controlling the inflammatory response in mucosal tissues. Here, we studied the role of IL-22 in endometrial recovery after inflammation-triggered abortion. Fecundity of mice was studied in consecutive matings of the same animals after lipopolysaccharide (LPS) (10 µg per mouse)-triggered abortion. The fecundity rate after the second mating was substantially different between IL-22 knockout (IL-22^−/−) (9.1%) and wild-type (WT) (71.4%) mice (p < 0.05), while there was no difference between the groups in the initial mating, suggesting that IL-22 deficiency might be associated with secondary infertility. A considerable difference was observed between IL-22^−/− and WT mice in the uterine clearance following LPS-triggered abortion. Gross examination of the uteri of IL-22^−/− mice revealed non-viable fetuses retained inside the horns (delayed clearance). In contrast, all WT mice had completed abortion with total clearance after LPS exposure. We also discovered that IL-22 deficiency is associated with a decreased expression of tight junctions (claudin-2 and claudin-10) and cell surface pathogen protectors (mucin-1). Moreover, IL-22 has a role in the remodeling of the uterine tissue in the inflammatory environment by regulating epithelial–mesenchymal transition markers called E- and N-cadherin. Therefore, IL-22 contributes to the proper regeneration of endometrial layers after inflammation-triggered abortion. Thus, it might have a practical significance to be utilized as a treatment option postpartum (enhanced regeneration function) and in secondary infertility caused by inflammation (enhanced barrier/protector function).

LSR antibody promotes apoptosis and disrupts epithelial barriers via signal pathways in endometrial cancer

Lipolysis-stimulated lipoprotein receptor (LSR), a lipid metabolism-related factor localized in tricellular tight junctions (tTJs), plays an important role in maintaining the epithelial barrier. LSR is highly expressed in well-differentiated endometrial endometrioid carcinoma (EEC), and its expression decreases during malignancy. Angubindin-1, a novel LSR ligand peptide, regulates tTJs without cytotoxicity, enhances paracellular permeability, and regulates epithelial barrier via c-Jun N-terminal kinase (JNK)/cofilin. In this study, we investigated the immune-modulatory roles of an anti-LSR antibody in the treatment of EEC in vitro compared to those of angubindin-1. We prepared an antibody against the extracellular N-terminal domain of human LSR (LSR-N-ab) and angubindin-1. EEC cell-line Sawano cells in 2D and 2.5D cultures were treated with 100 μg/ml LSR-N-ab or 2.5 μg/ml angubindin-1 with or without protein tyrosine kinase 2β inhibitor PF431396 (PF43) and JNK inhibitor SP600125 (SP60) at 10 μM. Treatment with LSR-N-ab and angubindin-1 decreased LSR at the membranes of tTJs and the activity of phosphorylated LSR and phosphorylated cofilin in 2D culture. Treatment with LSR-N-ab and angubindin-1 decreased the epithelial barrier measured as TEER values in 2D culture and enhanced the epithelial permeability of FD-4 in 2.5D culture. Treatment with LSR-N-ab, but not angubindin-1, induced apoptosis in 2D culture. Pretreatment with PF43 and SP60 prevented all the changes induced by treatment with LSR-N-ab and angubindin-1. Treatment with LSR-N-ab and angubindin-1 enhanced the cell metabolism measured as the mitochondrial respiration levels in 2D culture. LSR-N-ab and angubindin-1 may be useful for therapy of human EEC via enhanced apoptosis or drug absorption.

The Roles of Tricellular Tight Junction Protein Angulin-1/Lipolysis-Stimulated Lipoprotein Receptor (LSR) in Endometriosis and Endometrioid-Endometrial Carcinoma

Tight junction proteins play roles beyond permeability barriers functions and control cell proliferation and differentiation. The relation between tight junctions and the signal transduction pathways affects cell growth, invasion and migration. Abnormality of tight junction proteins closely contributes to epithelial mesenchymal transition (EMT) and malignancy of various cancers. Angulin-1/lipolysis-stimulated lipoprotein receptor (LSR) forms tricellular contacts that has a barrier function. Downregulation of angulin-1/LSR correlates with the malignancy in various cancers, including endometrioid-endometrial carcinoma (EEC). These alterations have been shown to link to not only multiple signaling pathways such as Hippo/YAP, HDAC, AMPK, but also cell metabolism in ECC cell line Sawano. Moreover, loss of angulin-1/LSR upregulates claudin-1, and loss of apoptosis stimulating p53 protein 2 (ASPP2) downregulates angulin-1/LSR. Angulin-1/LSR and ASPP2 concentrate at both midbody and centrosome in cytokinesis. In EEC tissues, angulin-1/LSR and ASPP2 are reduced and claudin-2 is overexpressed during malignancy, while in the tissues of endometriosis changes in localization of angulin-1/LSR and claudin-2 are seen. This review highlights how downregulation of angulin-1/LSR promotes development of endometriosis and EEC and discusses about the roles of angulin-1/LSR and its related proteins, including claudins and ASPP2.

Claudins: New Players in Human Fertility and Reproductive System Cancers

Claudins are major integral proteins of tight junctions (TJs), the apical cell-cell adhesions that enable maintaining polarity of epithelial cells, their differentiation, and cell signaling. A number of studies have indicated that claudins might play a crucial role in both physiology and pathogenesis. Their tissue-specific expression was originally linked to the development of different types of cancer and triggered a hope to use them as diagnostic or prognostic markers. However, it seems that their expression is more complex than that, and undoubtedly, claudins participate in one of the most important molecular events in cells. This review summarizes the recent research evaluating the role of claudins in fertility and the most common endocrine-dependent cancers in the reproductive system and highlights the crucial role of claudins both in human fertility and the most common cancers.

Targeting claudin-3 suppresses stem cell-like phenotype in nonsquamous non-small-cell lung carcinoma

AIM

To determine the role of claudin-3 in cancer stemness in nonsquamous non-small-cell lung carcinoma (NSCLC).

MATERIALS & METHODS

In vitro/vivo extreme limiting dilution analysis and the side population assay were used to investigate the role of claudin-3 in regulating cancer stemness in nonsquamous NSCLC.

RESULTS & CONCLUSION

Claudin-3 depletion decreased the formation rates of spheres and tumors and increased cisplatin sensitivity. Claudin-3 was also identified as one downstream target of estrogen receptor-α in regulating cancer stemness. Moreover, targeting CLDN-3 transcription by small molecules including withaferin A, estradiol and fulvestrant suppressed cancer stemness and reversed chemoresistance. These results demonstrated claudin-3 is one positive regulator of cancer stemness in nonsuqamous NSCLC.

Immunohistochemical expression of hormone receptors, Ki-67, endoglin (CD105), claudins 3 and 4, MMP-2 and -9 in endometrial polyps and endometrial cancer type I

Objective

The aim of this study was to investigate the malignant potential of endometrial polyps (EP) by assessing the immunoexpressions of both estrogen receptor (ER) and progesterone receptor (PR), Ki-67 cell proliferation index, neovascularization network (endoglin – CD105), cellular adhesion molecules (claudins 3 and 4), and extracellular matrix proteins (MMP-2 and -9) in both EP and endometrioid adenocarcinoma (type I) in comparison with the normal endometrium.

Study design

This is a cross-sectional comparative study. Patients were identified from the database of Botucatu Medical School, São Paulo State University (BMS-UNESP) Clinical Pathology Laboratory.

Setting

The study was conducted using a convenience sample of patients attending the Sectors of Gynecologic Endoscopy and Family Planning and Gynecologic Oncology of the Department of Gynecology and Obstetrics of BMS-UNESP, Brazil.

Patients

A total of 90 women were allocated into the following three groups: EP without atypia (EP, n=30), endometrioid endometrial cancer (EC, n=30), and normal endometrium (control, n=30).

Methods

Epidemiological and clinical data were obtained by reviewing medical records. Adenocarcinoma and control cases were assessed using the tissue microarray technique. The immunoexpressions of ER, PR, Ki-67, CD105, claudins 3 and 4, and MMP-2 and -9 were assessed in paraffin blocks containing sections of the largest polyploid lesion fragment and tissue microarray recipient blocks.

Major results

Compared to the control group, significant differences in the expression of ER (P<0.001), PR (P<0.05), Ki-67 (P<0.001), CD105 (P<0.001), and claudin 3 (P<0.001) were observed in EP and EC. No significant differences were found between EP and EC (P≥0.05). MMP-2 and -9 expression were nearly absent in all groups.

Conclusion

The malignant potential of EP could not be determined through the immunohistochemical parameters used in this study. No MMP-2 or -9 expression was observed in any endometrial tissue sample. Further studies are necessary for a better understanding of the biomolecular mechanisms underlying endometrial carcinogenesis.

Imaging of Claudin-4 in Pancreatic Ductal Adenocarcinoma Using a Radiolabelled Anti-Claudin-4 Monoclonal Antibody

PURPOSE

Despite its widespread use, the positron emission tomography (PET) radiotracer 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) has been shown in clinical settings to be ineffective for improving early diagnosis of pancreatic ductal adenocarcinoma (PDAC). A promising biomarker for PDAC detection is the tight junction protein claudin-4. The purpose of this study was to evaluate a new single-photon emission computed tomography (SPECT) imaging agent, [111In]anti-claudin-4 mAb, with regard to its ability to allow visualisation of claudin-4 in a xenograft and a genetically engineered mouse model of PDAC.

PROCEDURES

The ability of [111In]anti-claudin-4 mAb to selectively target claudin-4 was assessed using two human xenograft tumour models with differential claudin-4 status in mice. [111In]anti-claudin-4 mAb was also used to detect PDAC development in genetically engineered KPC mice. The PDAC status of these mice was confirmed with [18F]FDG-PET, magnetic resonance imaging (MRI), histology, and immunofluorescence microscopy.

RESULTS

High uptake of [111In]anti-claudin-4 mAb was observed in PDAC xenografts in mice, reaching 16.9 ± 4.5 % of injected dose per gram (% ID/g) at 72 h post-injection. This uptake was mediated specifically by the expression of claudin-4. Uptake of [111In]anti-claudin-4 mAb also enabled clear visualisation of spontaneous PDAC formation in KPC mice.

CONCLUSIONS

[111In]anti-claudin-4 mAb allows non-invasive detection of claudin-4 upregulation during development of PDAC and could potentially be used to aid in the early detection and characterisation of this malignancy.

Quantitative PCR marker genes for endometrial adenocarcinoma

Endometrial adenocarcinoma is a common malignancy in women worldwide, with formation of remote metastasis occurring following oncological treatment. Circulating tumor cells (CTCs) are regarded to be the origin of haematogenous metastasis formation. The present study aimed to identify suitable marker genes using a quantitative polymerase chain reaction (qPCR) approach to detect CTCs from blood samples of patients with endometrial carcinoma. Therefore, RNA was isolated from endometrial adenocarcinoma cell lines and from healthy endometrial tissue and reverse transcribed to cDNA, which was then used in qPCR on a number of marker genes. Cytokeratin 19 and claudin 4 were identified as suitable marker genes for CTCs in endometrial adenocarcinoma, due to their high expression in the majority of the cell lines investigated. The expression values of the genes examined varied widely between the different cell lines, which is similar to the variation in the patient samples. Therefore, the necessity for a set of genes for CTC detection and not one single marker gene is demonstrated. qPCR is a fast, cost‑efficient and easy to perform technique, which may be used in the detection of CTCs. Investigation of the occurrence of CTCs in cancer patients would aid in the prevention of metastasis and thereby refine treatment.

Overexpression of Claudin-1 is Associated with Advanced Clinical Stage and Invasive Pathologic Characteristics of Oral Squamous Cell Carcinoma

Claudins constitute a group of principal proteins forming the tight junctional complex. The altered expression of selected claudins has been reported in several human cancers. The purpose of this study was to investigate the expression of claudin-1 and claudin-4 in oral squamous cell carcinoma (OSCC) and examine its relationship with patient clinical-pathologic features. Forty-five OSCC cases were enrolled. Patient clinical, pathologic and follow-up data were reviewed and the claudin-1 and claudin-4 expression was analyzed immunohistochemically. Positive claudin-1 and claudin-4 immunoreactivities were noted in 86.7 and 80 % of cases, respectively. The majority of cases showed the staining in less than 25 % of cancer cells. The increased claudin-1 expression was significantly associated with the high pathologic grade, the presence of microscopic perineural invasion, vascular invasion, nodal metastasis, and advanced clinical stage. No relationship between various clinico-pathologic parameters and differential claudin-4 expression was observed. Claudin-1 may play a role in OSCC progression and could serve as a prognostic marker of advanced disease.