Claudin 1 in Breast Cancer: New Insights

Claudins in Cancer: A Current and Future Therapeutic Target

Claudins are a family of 27 proteins that have an important role in the formation of tight junctions. They also have an important function in ion exchange, cell mobility, and the epithelial-to-mesenchymal transition, the latter being very important in cancer invasion and metastasis. Therapeutic targeting of claudins has been investigated to improve cancer outcomes. Recent evidence shows improved outcomes when combining monoclonal antibodies against claudin 18.2 with chemotherapy for patients with gastroesophageal junction cancer. Currently, chimeric antigen receptor T-cells targeting claudin 18 are under investigation. In this review, we will discuss the major functions of claudins, their distribution in the normal as well as cancerous tissues, and their effect in cancer metastasis, with a special focus on the therapeutic targeting of claudins to improve cancer outcomes.

Brain metastasis-associated fibroblasts secrete fucosylated PVR/CD155 that induces breast cancer invasion

Brain metastasis cancer-associated fibroblasts (bmCAFs) are emerging as crucial players in the development of breast cancer brain metastasis (BCBM), but our understanding of the underlying molecular mechanisms is limited. In this study, we aim to elucidate the pathological contributions of fucosylation (the post-translational modification of proteins by the dietary sugar L-fucose) to tumor-stromal interactions that drive the development of BCBM. Here, we report that patient-derived bmCAFs secrete high levels of polio virus receptor (PVR), which enhance the invasive capacity of BC cells. Mechanistically, we find that HIF1α transcriptionally upregulates fucosyltransferase 11, which fucosylates PVR, triggering its secretion from bmCAFs. Global phosphoproteomic analysis of BC cells followed by functional verification identifies cell-cell junction and actin cytoskeletal signaling as modulated by bmCAF-secreted, -fucosylated PVR. Our findings delineate a hypoxia- and fucosylation-regulated mechanism by which bmCAFs contribute to the invasiveness of BCBM in the brain.

Upregulated LAMA3 modulates proliferation, adhesion, migration and epithelial‑to‑mesenchymal transition of cholangiocarcinoma cells

A poor outcome for cholangiocarcinoma (CCA) patients is still a clinical challenge. CCA is typically recognized by the desmoplastic nature, which accounts for its malignancy. Among various extracellular matrix proteins, laminin is the most potent inducer for CCA migration. Herein, we accessed the expression profiles of laminin gene family and explored the significance of the key laminin subunit on CCA aggressiveness. Of all 11 laminin genes, LAMA3, LAMA5, LAMB3 and LAMC2 were concordantly upregulated based on the analysis of multiple public transcriptomic datasets and also overexpressed in Thai CCA cell lines and patient tissues in which LAMA3A upregulated in the highest frequency (97%) of the cases. Differential expression genes (DEGs) analysis of low and high laminin signature groups revealed LAMA3 as the sole common DEG in all investigated datasets. Restratifying CCA samples according to LAMA3 expression indicated the association of LAMA3 in the focal adhesion pathway. Silencing LAMA3 revealed that it plays important roles in CCA cell proliferation, adhesion, migration and epithelial-to-mesenchymal transition. Taken together, this research signifies the roles of dysregulated ECM homeostasis in CCA malignancy and highlights, for the first time, the potential usage of LAMA3 as the diagnostic biomarker and the therapeutic target to tackle the CCA stromal.

Stem Cell Protein PIWIL2 Promotes EMT Process and Stem Cell-Like Properties in MCF7 Breast Cancer Cell Line

Background

Piwi-like RNA-mediated gene silencing 2 (PIWIL2) is a member of AGO/PIWI gene family, which is enriched in cancer stem cells (CSCs). The purpose of this research was to investigate the overexpression of PIWIL2 and its role in the induction of EMT and CSC properties in MCF7 breast cancer cell line.

Materials and Methods

MCF7 cells were transfected with the human gene PIWIL2 (Hili) under the control of CMV promoter utilizing the neon electroporation method. Subsequently, the selection was conducted using G418, and doubling time was calculated in the transformed and control cells. RT and real-time PCR were also performed to analyze the expression of epithelial and mesenchymal genes and those related to CSCs.

Results

According to the observations from this study, transfecting MCF7 cells with PIWIL2 triggered the conversion of epithelial cells to mesenchymal cells and induced the genes specific for breast CSCs, which was coincident with 9-h reduction in the doubling time of the transfected cells. Furthermore, the molecular analyses revealed a significant reduction in the expression of epithelial markers, while a significant increase was detected in the expression of mesenchymal genes and many CSC biomarkers.

Conclusion

PIWIL2 protein acts as a master regulatory protein that is able to manipulate the transcription through specific signaling pathways, which allow the cells to gain stem cell-like properties.

Navigating the Blood-Brain Barrier: Challenges and Therapeutic Strategies in Breast Cancer Brain Metastases

Breast cancer (BC) is the most common cancer in women, with metastatic BC being responsible for the highest number of deaths. A frequent site for BC metastasis is the brain. Brain metastasis derived from BC involves the cooperation of multiple genetic, epigenetic, angiogenic, and tumor-stroma interactions. Most of these interactions provide a unique opportunity for development of new therapeutic targets. Potentially targetable signaling pathways are Notch, Wnt, and the epidermal growth factor receptors signaling pathways, all of which are linked to driving BC brain metastasis (BCBM). However, a major challenge in treating brain metastasis remains the blood-brain barrier (BBB). This barrier restricts the access of unwanted molecules, cells, and targeted therapies to the brain parenchyma. Moreover, current therapies to treat brain metastases, such as stereotactic radiosurgery and whole-brain radiotherapy, have limited efficacy. Promising new drugs like phosphatase and kinase modulators, as well as BBB disruptors and immunotherapeutic strategies, have shown the potential to ease the disease in preclinical studies, but remain limited by multiple resistance mechanisms. This review summarizes some of the current understanding of the mechanisms involved in BC brain metastasis and highlights current challenges as well as opportunities in strategic designs of potentially successful future therapies.

Detection of Increased Expression of Claudin-1 in Triple-Negative Breast Cancer: Analysis and Clinical-Pathological Correlation

Background Triple-negative breast cancer (TNBC) is a highly aggressive disease that lacks therapeutic targets and prognostic biomarkers. Claudin-1 is a well-described tight junction protein with prognostic value in many human cancers. Aims The need for the discovery of biomarkers of TNBC disease was a major reason for this study. Claudin-1 is a tight junction protein that has shown promising results in the prognosis and management of cancer in general. In the breast, claudin-1 expression and significance have shown variable results, especially in TNBC patients. Our study assessed expression of claudin-1 in a group of TNBC patients, and correlated this expression with clinical-pathological parameters, and with the expression of β-catenin. Materials and methods Tissues from a group of 52 TNBC patients were retrieved from the archives of the community hospital. All related information including demographical, pathologic and clinical data were retrieved. Immunohistochemistry assays of a rabbit polyclonal antibody anti-human claudin-1 were applied using the avidin-biotin peroxidase methodology. Results A statistically significant majority of TNBC cases positively expressed claudin-1 (81%, χ2=13.705; p<0.001). Most TNBC cases had grade 2 β-catenin expression (77.5%; p<0.001), and positive expression for claudin-1 correlated with that of β-catenin (χ2= 23.757; p<0.001). Claudin-1 and β-catenin expressions within tumour cells shared several features including absent or weakness of membranous expression, and redistribution of both proteins to the cytoplasm of tumour cells, and in some cases to the nuclei of these cells. Claudin-1 expression also correlates with adverse survival outcomes, where only four of 20 claudin-1-positive patients who received neo-adjuvant chemotherapy (NAC) achieved pathological complete response (pCR). Conclusions The above presents a complex role of claudin-1 in TNBC patients. In this study, claudin-1 expression was associated with poor prognostic features including invasion, metastases and adverse clinical outcomes. Claudin-1 expression in TNBC correlated with the expression of β-catenin, an important oncogene and a major contributor to the epithelial mesenchymal transition (EMT) phenomenon. Overall, the above results may serve as an impetus for further mechanistic studies to assess the exact role of claudin-1 in TNBC and its possible use in the management of this subset of breast cancer.

Claudins: The Newly Emerging Targets in Breast Cancer

Claudin-low breast cancers are recently described entities showing low expression of certain claudins and cell adhesion molecules. Claudins constitute the backbone of tight junctions (TJs) formed between 2 cells. Their dysregulation plays a vital role in tumorigenesis. First part of the article focuses on the role of claudins in the TJ organization, their structural-functional characteristics, and post-transcriptional and translational modifications. The latter part of the review attempts to summarize existing knowledge regarding the status of claudins in breast cancer. The article also provides an overview of the effect of claudins on tumor progression, metastasis, stemness, chemotherapy resistance, and their crosstalk with relevant signaling pathways in breast cancer. Claudins can act as 2-edged swords in tumors. Some claudins have either tumor-suppressive/ promoting action, while others work as both in a context-dependent manner. Claudins regulate many important events in breast cancer. However, the intricacies involved in their activity are poorly understood. Post-translational modifications in claudins and their impact on TJ integrity, function, and tumor behavior are still unclear. Although their role in adverse events in breast cancer is recognized, their potential to serve as relevant targets for future therapeutics, especially for difficult-to-treat subtypes of the above malignancy, remains to be explored.

CLDN1 Sensitizes Triple-Negative Breast Cancer Cells to Chemotherapy

Simple Summary

Triple-negative breast cancer (TNBC) treatment represents a major challenge in oncology. TNBC evolves into chemotherapy resistance for 60 to 70% of the patients. About 77% of the TNBC displays a lack of claudin-1 (CLDN1), a major tight junction component. We demonstrated that CLDN1 increased the sensitivity of TNBC cell lines to the main chemotherapeutic agents commonly used for breast cancer treatment. Our data support the idea that CLDN1 may be a good predictive chemotherapy response marker to help therapeutic management of TNBC patients. In longer terms, this study could allow new treatment protocols creation aimed to induce CLDN1 expression in TNBCs to increase their sensitivity to chemotherapy.

Abstract

Triple-negative breast cancer (TNBC) is an aggressive subtype that constitutes 15–20% of breast cancer cases worldwide. Current therapies often evolve into chemoresistance and lead to treatment failure. About 77% of the TNBC lacks claudin-1 (CLDN1) expression, a major tight junction component, and this absence is correlated with poorer prognostic. Little is known about CLDN1 role on the chemosensitivity of breast cancer. Our clinical data analysis reveals that CLDN1 low expression is correlated to a poor prognostic in TNBC patients. Next, the sensitivity of various TNBC “claudin-1-high” or “claudin-1-low” cells to three compounds belonging to the main class of chemotherapeutic agents commonly used for the treatment of TNBC patients: 5-fluorouracil (5-FU), paclitaxel (PTX) and doxorubicin (DOX). Using RNA interference and stable overexpressing models, we demonstrated that CLDN1 expression increased the sensitivity of TNBC cell lines to these chemotherapeutic agents. Taken together, our data established the important role of CLDN1 in TNBC cells chemosensitivity and supported the hypothesis that CLDN1 could be a chemotherapy response predictive marker for TNBC patients. This study could allow new treatment protocols creation aimed to induce CLDN1 expression in TNBCs to increase their sensitivity to chemotherapy.

The heparan sulphate proteoglycan Syndecan-1 (CD138) regulates tumour progression in a 3D model of ductal carcinoma in situ of the breast

Ductal carcinoma in situ (DCIS) is a form of breast cancer that is restricted to the lactiferous ducts and has not yet invaded the surrounding breast tissue. Dysregulation of the transmembrane heparan sulphate proteoglycan Syndecan-1 (Sdc-1) plays a role in tumour progression of invasive breast cancer (IBC). In DCIS, Sdc-1, c-Met and E-cadherin are part of a proangiogenic expression signature. In this study, we employed a siRNA knockdown approach in the DCIS model cell line MCF10A DCIS.com to investigate a potential connection between Sdc-1 and epithelial mesenchymal transition (EMT), proteolysis and the Rho kinase pathway. Analysis of gene expression data of the TNMplot.com database revealed that Sdc-1 expression was higher in primary breast tumours compared to metastases. The impact of Sdc-1-depletion on the cellular phenotype was investigated in a Matrigel-based three-dimensional cell culture model. Sdc-1 depletion resulted in the formation of larger spheroids and the formation of invasive protrusions. Application of matrix metalloproteinase (MMP) and Rho kinase inhibitors could block the Sdc-1-induced phenotype. qPCR analysis of Sdc-1-depleted cells in two-dimensional culture revealed upregulated expression of the EMT-markers CDH1, FN-1, CLDN1, the proteolysis markers MMP3, and MMP9, and HPSE, while MMP2, VIM and ROCK-2 were downregulated. Immunocytochemistry confirmed upregulation of MMP9 and fibronectin, the latter being particular prominent after ROCK inhibition. STRING analysis confirmed an interaction of the investigated gene products at the protein level. Our results suggest that diminished Sdc-1 expression plays a role in DCIS progression to IBC through deregulation of proteolytic factors and a partial EMT.

Cadherin‑16 inhibits thyroid carcinoma cell proliferation and invasion

Cadherin-16 (CDH16), a member of the cadherin family of adhesion molecules, serves an important role in the formation and maintenance of the thyroid follicular lumen. Decreased expression of CDH16 has been reported to be associated with tumor stage in papillary thyroid cancer (PTC); however, previous analyses have been limited and the biological role of CDH16 in different subtypes of TC is unknown. To investigate the role of CDH16 in the occurrence and development of TC, bioinformatic analysis of three TC subtypes (PTC, follicular cell-derived TC and anaplastic TC) was performed using an extended data set from the Gene Expression Omnibus database, with additional confirmation using data from The Cancer Genome Atlas, as well as biopsies from 35 patients with PTC and TC or follicular cell lines. According to the dataset analysis, CDH16 was downregulated in PTC and follicular cell-derived and anaplastic TC; the downregulation in PTC was independent of DNA copy number variation. Furthermore, low expression levels of CDH16 were significantly correlated with tumor size, lymph node metastasis status and disease stage in 35 patients with PTC. Gene Set Enrichment Analysis suggested that CDH16 participated in DNA replication and cell adhesion pathways. To evaluate CDH16 activity, CDH16 was overexpressed in TC-derived BCPAP cells. CDH16 overexpression inhibited cell proliferation, migration and invasion and induced apoptosis by downregulating proteins associated with DNA replication and cell adhesion. These results support the identification of CDH16 as a valuable target for TC prognosis and therapy and, to the best of our knowledge, represent the first direct demonstration of its mechanistic role in TC.

Expression of tight junction transmembrane protein Claudin-1 in gastric carcinoma and effects on tumor cell proliferation, invasion and migration

Background: Claudin-1 is involved in various cancers, but its expression and role in gastric carcinoma remain unclear.

Materials and Methods: Gastric carcinoma and adjacent normal tissues were harvested from 60 patients. Claudin-1 expression was detected by RT-qPCR. The expressions in human gastric carcinoma MKN45, SGC7901 and MKN28 cells and immortalized human gastric epithelium GES-1 cells were determined by RT-qPCR and Western blotting. Claudin-1 was overexpressed in SGC7901 cells by lentiviral transfection, and they were divided into Control (untransfected), normal control (NC) (transfected with lentiviral vector) and Claudin-1 (transfected with Claudin-1 overexpression lentivirus) groups. The proliferation, invasion and migration of gastric carcinoma cells were detected through cell counting kit-8, Transwell and wound healing assays, respectively. The effects of Claudin-1 on the expressions of epithelial-mesenchymal transition (EMT) marker proteins E-cadherin and N-cadherin were detected by Western blotting. Ten 4-week-old male BALB/c nude mice were subcutaneously injected with lentivirus-treated SGC7901 cells to establish the transplanted tumor model, and the effect of overexpression of Claudin-1 was explored.

Results: The expression of Claudin-1 in gastric carcinoma tissues was significantly lower than that in adjacent tissues (P<0.05). Overexpression of Claudin-1 significantly inhibited the proliferation, invasion and migration of SGC7901 cells, increased the expression of E-cadherin, and decreased that of N-cadherin (P<0.05). Overexpression of Claudin-1 in the mouse model significantly inhibited the growth of subcutaneous transplanted tumors (P<0.05).

Conclusion: Claudin-1 has low expression in gastric carcinoma tissues. Overexpression of Claudin-1 inhibits the proliferation, invasion, migration, and EMT of gastric carcinoma cells, and subcutaneous tumorigenesis in nude mice.

Comparison of Fixation Methods for the Detection of Claudin 1 and E-Cadherin in Breast Cancer Cell Lines by Immunofluorescence

The tight junction membrane protein claudin 1 and the adherens junction protein E-cadherin play critical roles in cell-cell communication and in cell signaling. As a result, their protein levels and distribution in cancer have been a focus of cancer researchers in recent years. The loss of sensitivity to contact inhibition and the establishment of invasive properties in cancer are thought to be a result of the mislocalization of these membrane proteins to the cytoplasm. However, reports on their distribution and levels have been inconsistent. It is therefore critical that the techniques used to determine the cellular localization of these proteins be both consistent and reliable. This study was undertaken to determine the optimal fixation method, methanol or formalin, for the detection of claudin 1 and E-cadherin by immunofluorescence in five different human breast cancer cell lines. Both methods exhibited staining of the cell membrane and cytoplasm, but the strongest and most distinct signals were obtained using methanol fixation. Interestingly, cell-specific differences were also observed that appeared to be associated with levels of claudin 1 and E-cadherin as seen by Western blotting. Therefore, when evaluating cellular localization of the junction proteins claudin 1 and E-cadherin, expression level and cell type differences must be considered.

Bioactive glass promotes the barrier functional behaviors of keratinocytes and improves the Re-epithelialization in wound healing in diabetic rats

Upon skin injury, re-epithelialization must be triggered promptly to restore the integrity and barrier function of the epidermis. However, this process is often delayed or interrupted in chronic wounds like diabetic foot ulcers. Considering that BG particles can activate multiple genes in various cells, herein, we hypothesized that bioactive glass (BG) might be able to modulate the barrier functional behaviors of keratinocytes. By measuring the transepithelial electrical resistance (TEER) and the paracellular tracer flux, we found the 58S-BG extracts substantially enhanced the barrier function of keratinocyte monolayers. The BG extracts might exert such effects by promoting the keratinocyte differentiation and the formation of tight junctions, as evidenced by the increased expression of critical differentiation markers (K10 and involucrin) and TJ protein claudin-1, as well as the altered subcellular location of four major TJ proteins (claudin-1, occludin, JAM-A, and ZO-1). Besides, the cell scratch assay showed that BG extracts induced the collective migration of keratinocytes, though they did not accelerate the migration rate compared to the control. The in vivo study using a diabetic rat wound model demonstrated that the BG extracts accelerated the process of re-epithelialization, stimulated keratinocyte differentiation, and promoted the formation of tight junctions in the newly regenerated epidermis. Our findings revealed the crucial effects of BGs on keratinocytes and highlighted its potential application for chronic wound healing by restoring the barrier function of the wounded skin effectively.

The Breast Tumor Microenvironment: A Key Player in Metastatic Spread

The tumor microenvironment plays a pivotal role in the tumorigenesis, progression, and metastatic spread of many cancers including breast. There is now increasing evidence to support the observations that a bidirectional interplay between breast cancer cells and stromal cells exists within the tumor and the tumor microenvironment both at the primary tumor site and at the metastatic site. This interaction occurs through direct cell to cell contact, or by the release of autocrine or paracrine factors which can activate pro-tumor signaling pathways and modulate tumor behavior. In this review, we will highlight recent advances in our current knowledge about the multiple interactions between breast cancer cells and neighboring cells (fibroblasts, endothelial cells, adipocytes, innate and adaptive immune cells) in the tumor microenvironment that coordinate to regulate metastasis. We also highlight the role of exosomes and circulating tumor cells in facilitating breast cancer metastasis. We discuss some key markers associated with stromal cells in the breast tumor environment and their potential to predict patient survival and guide treatment. Finally, we will provide some brief perspectives on how current technologies may lead to the development of more effective therapies for the clinical management of breast cancer patients.

Cell polarity and cell adhesion associated gene expression differences between invasive micropapillary and no special type breast carcinomas and their prognostic significance

Invasive micropapillary carcinoma of the breast (IMPC) has been in the focus of several studies given its specific histology and clinicopathological course. We analysed mRNA expression profiles and the prognostic value of 43 genes involved in cell polarity, cell-adhesion and epithelial-mesenchymal transition (EMT) in IMPC tumors and compared them to invasive breast carcinomas of no special type (IBC-NST). IMPCs (36 cases), IBC-NSTs (36 cases) and mixed IMPC-IBC NSTs (8 cases) were investigated. mRNA expression level of selected genes were analysed using the NanoString nCounter Analysis System. Distant metastases free survival (DMFS) intervals were determined. Statistical analysis was performed using Statistica 13.5 software. Twelve genes showed significantly different expression in the IMPC group. There was no difference in DMFS according to histological type (IBC-NST vs. IMPC). High CLDN3, PALS1 and low PAR6 expression levels in the entire cohort were associated with shorter DMFS, and PALS1 was proven to be grade independent prognostic factor. Positive lymph node status was associated with higher levels of AKT1 expression. Differences in gene expression in IMPC versus IBC-NST may contribute to the unique histological appearance of IMPCs. No marked differences were observed in DMFS of the two groups. Altered gene expression in the mTOR signaling pathway in both tumor subtypes highlights the potential benefit from AKT/mTOR inhibitors in IMPCs similarly to IBC-NSTs.

Context-Dependent Roles of Claudins in Tumorigenesis

The barrier and fence functions of the claudin protein family are fundamental to tissue integrity and human health. Increasing evidence has linked claudins to signal transduction and tumorigenesis. The expression of claudins is frequently dysregulated in the context of neoplastic transformation. Studies have uncovered that claudins engage in nearly all aspects of tumor biology and steps of tumor development, suggesting their promise as targets for treatment or biomarkers for diagnosis and prognosis. However, claudins can be either tumor promoters or tumor suppressors depending on the context, which emphasizes the importance of taking various factors, including organ type, environmental context and genetic confounders, into account when studying the biological functions and targeting of claudins in cancer. This review discusses the complicated roles and intrinsic and extrinsic determinants of the context-specific effects of claudins in cancer.

Dysregulated expression of claudins in cancer

Claudins are adhesion molecules located at the tight junctions between epithelial cells. A series of studies have now reported aberrant expression of claudin proteins in the context of neoplastic transformation, suggesting its role in tumorigenesis. However, the precise mechanisms are still not well understood. Studies on expression alterations of claudins have revealed a range of outcomes that reflect the complexity of claudins in terms of spatial localization, tumor type and stage of disease. The diverse and dynamic expression patterns of claudins in cancer are tightly controlled by a wide range of regulatory mechanisms, which are commonly modulated by oncogenic signaling pathways. The present review summarizes the recent knowledge describing the dysregulation of claudin expression in cancer and discusses the intrinsic and extrinsic determinants of the context-specific expression patterns of claudins.

Expression of Claudin-1 in laryngeal squamous cell carcinomas (LSCCs) and its significance

BACKGROUND

A large body of scientific evidence points to the important roles of tight junction proteins in tumor development, progression and dissemination. The larynx has only a few studies, analyzing the role of this group of junctional proteins in its oncogenesis. In this study, the author sheds some light on the expression and possible role of claudin-1 in laryngeal squamous cell carcinomas.

MATERIALS AND METHODS

This study analyzed the expression of claudin-1, using immunohistochemistry, in a tissue microarray of 80 cases of laryngeal squamous cell cancers. Clinicopathological parameters were analyzed according to claudin-1 expression in the tissue microarray. Furthermore, the expression of slug/snail1, an Epithelial-Mesenchymal Transition (EMT) linked protein, was analyzed by immunohistochemistry in the same microarray, and the expressions of the two proteins were assessed for correlation.

RESULTS

A significant majority of laryngeal squamous cell cancers exhibited positive expression of claudin-1 proteins. The majority of those tumors expressed claudin-1 in their cytoplasm. The overall majority of those same tumors also exhibited a cytoplasmic shift of the slug-snail-1 protein from the nuclei to the cytoplasm. There was also evidence of correlation of the two proteins' expressions in the cytoplasm of laryngeal tumors.

CONCLUSION

The above may suggest a role for claudin-1 in the development and progression of laryngeal squamous cell carcinoma. Overall, claudin-1's aberrant expression in laryngeal cancer is in line with evidence seen in other head and neck cancers. Its co-expression with slug/snail-1 in LSCC patients should be investigated further to understand the nature of the relationship of the two proteins in LSCC and their possible contribution to its development and progression.

CD9, a tetraspanin target for cancer therapy?

In the present minireview, we intend to provide a brief history of the field of CD9 involvement in oncogenesis and in the metastatic process of cancer, considering its potential value as a tumor-associated antigenic target. Over the years, CD9 has been identified as a favorable prognostic marker or predictor of metastatic potential depending on the cancer type. To understand its implications in cancer beside its use as an antigenic biomarker, it is essential to know its physiological functions, including its molecular partners in a given cell system. Moreover, the discovery that CD9 is one of the most specific and broadly expressed markers of extracellular membrane vesicles, nanometer-sized entities that are released into extracellular space and various physiological body fluids and play a role in intercellular communication under physiological and pathological conditions, notably the establishment of cancer metastases, has added a new dimension to our knowledge of CD9 function in cancer. Here, we will discuss these issues as well as the possible cancer therapeutic implications of CD9, their limitations, and pitfalls.

Nanodiamonds inhibit scratch-wound repair in lung epithelial cell monolayers by blocking cell migration and inhibiting cell proliferation

Proliferation and migration of lung epithelial cells following the injury to the epithelial lining of alveoli and airways in the lung are pivotal for remodeling and repair of the wound to restore normal lung function. In the present study, we examined the modulatory effect of carboxylated nanodiamonds (cNDs) on the cell division, migration, and adhesion of epithelial cells in the well-established in vitro model of wound repair and cell migration. Flow cytometry and confocal microscopy results indicated that both LA4 and A549 cells effectively internalized fluorescent carboxylated nanodiamonds (cFNDs) and the internalized nanodiamonds were essentially localized in the cytoplasmic region. Treatment with cNDs blocked the division and migration of cells to fill the scratch wound. Live cell imaging and time-lapse videography of the wound healing process indicated a significant inhibition of cell proliferation activity in cND-treated cells and blocked the wound repair process. Trans-well cell-migration assay results further support the inhibitory effect of cNDs on the cell migration process. Western blotting and immunofluorescence staining indicated that the crucial proteins involved in epithelial-mesenchymal transition (EMT) and cell migration i.e. β-catenin, Vimentin, NM-myosin, and Focal Adhesion Kinase (FAK) were downregulated after treatment with cNDs, while the expression of E-cadherin and Claudin-1, major cell adhesion markers remained unaltered. Taken together, our results indicate that the decline in cell proliferation activity, downregulation in the expression of various crucial protein like β-Catenin, NM-myosin, FAK, and Vimentin involved in the cell migration and unaltered expression of cell adhesion molecules E-cadherin and Claudin-1, may be the factors that contribute to the cND-mediated inhibition of EMT during the wound repair process in the monolayers of lung epithelial cells.

Claudin 1 inhibits cell migration and increases intercellular adhesion in triple-negative breast cancer cell line

Triple-negative "claudin 1 low" subtype represents around 15% of breast cancer and displays poor prognosis. The loss of claudin 1 is correlated with increased invasiveness and higher recurrence of the disease. Claudin 1 constitutes the backbone of the tight junction and is involved in cell-cell adhesion and migration processes. However, studies showed a controversial role of claudin 1 in cell migration. In this study, we aimed to clarify the effect of claudin 1 on migration of mesenchymal triple-negative breast cancer cells (TNBC). We reported that transient over expression of claudin 1 in MDA-MB-231 and Hs578T "claudin 1 low" TNBC cells inhibited cell migration using wound healing and transwell migration assays. In order to investigate more specifically the involvement of claudin 1, we generated stable MDA-MB-231 clones overexpressing claudin 1. Interestingly, the level of claudin 1 was correlated to the inhibition of cell migration and to the increase of cell-cell aggregation associated with enhanced formation of β-catenin adherens junction and occludin tight junction. Finally, we reported for the first time the key role of claudin 1 in the inhibition of cell migration process associated with the disappearance of stress fibers. These data suggest that re-expression of claudin 1 could be a promising strategy for regulating the migration of TNBC which no longer express claudin 1.

All Benign and Malignant Apocrine Breast Lesions Over-Express Claudin 1 and 3 and Are Negative for Claudin 4

Invasive apocrine carcinoma of the breast is an uncommon triple negative tumour that lacks a specific therapeutic target. Apocrine metaplasia of the breast shares common morphological features with apocrine carcinoma, and was previously found to consistently over-express claudin 1 and to lack claudin 4. This study was aimed at finding whether apocrine carcinoma, and other related apocrine breast lesions, have similar claudin profile. The immunohistochemical expression of claudin 1, 3 and 4 was studied in 11 cases of in situ and invasive apocrine breast carcinoma, 7 benign apocrine lesions and 45 consecutive morphologically non-apocrine triple negative breast carcinomas. All cases were also immunostained for Gross Cystic Disease Fluid Protein-15 (GCDFP-15), a marker for apocrine differentiation. Apocrine breast lesions maintained their expression pattern from benign through DCIS to invasive carcinoma; all showing strong expression of claudin 1 and 3 and absence of claudin 4. The same pattern of expression was seen in 2 out of the 45 morphologically non-apocrine tumours, but both showed strong positive staining for GCDFP-15. It is concluded that all benign and malignant apocrine lesions of the breast have a consistent pattern of claudin 1, 3 and 4 expression, suggesting the presence of a specific pathway for the development of invasive apocrine carcinoma. The over-expression of claudin 1 and 3 may have therapeutic implications as targets for managing apocrine cancers.

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.

Claudin-1, A Double-Edged Sword in Cancer

Claudins, a group of membrane proteins involved in the formation of tight junctions, are mainly found in endothelial or epithelial cells. These proteins have attracted much attention in recent years and have been implicated and studied in a multitude of diseases. Claudins not only regulate paracellular transepithelial/transendothelial transport but are also critical for cell growth and differentiation. Not only tissue-specific but the differential expression in malignant tumors is also the focus of claudin-related research. In addition to up- or down-regulation, claudin proteins also undergo delocalization, which plays a vital role in tumor invasion and aggressiveness. Claudin (CLDN)-1 is the most-studied claudin in cancers and to date, its role as either a tumor promoter or suppressor (or both) is not established. In some cancers, lower expression of CLDN-1 is shown to be associated with cancer progression and invasion, while in others, loss of CLDN-1 improves the patient survival. Another topic of discussion regarding the significance of CLDN-1 is its localization (nuclear or cytoplasmic vs perijunctional) in diseased states. This article reviews the evidence regarding CLDN-1 in cancers either as a tumor promoter or suppressor from the literature and we also review the literature regarding the pattern of CLDN-1 distribution in different cancers, focusing on whether this localization is associated with tumor aggressiveness. Furthermore, we utilized expression data from The Cancer Genome Atlas (TCGA) to investigate the association between CLDN-1 expression and overall survival (OS) in different cancer types. We also used TCGA data to compare CLDN-1 expression in normal and tumor tissues. Additionally, a pathway interaction analysis was performed to investigate the interaction of CLDN-1 with other proteins and as a future therapeutic target.

Sulforaphane Modulates Cell Migration and Expression of β-Catenin and Epithelial Mesenchymal Transition Markers in Breast Cancer Cells

BACKGROUND

We aimed to assess the effect of sulforaphane (SFN) on breast cancer cell migration and also its effect on the expression of epithelial mesenchymal transition (EMT) markers and β-catenin.

METHODS

This study was performed in Shahroud University of Medical Sciences, Shahroud, Iran from 2017-2018. In this experimental study, MDA-MB-231 cells were treated with different concentrations of SFN (5, 10, 20, 30 and 40 μM) at different time points of 24, 48, and 72 h. The control group was untreated cells. The inhibitory effects of different concentrations of SFN on cell migration at different time points were evaluated using scratch assay. Moreover, apoptosis was assessed by using flow cytometric analysis. The expression of β-catenin and EMT markers of ZEB1, fibronectin, and claudin-1 were determined by real-time PCR. Western blotting analysis of β-catenin was applied to determine its changes after SFN treatment.

RESULTS

SFN markedly inhibited the migration of cells at concentrations of 10, 20, 30, and 40μM after 24, 48, and 72 h. At relatively, high concentrations (30, 40μM), SFN induced apoptosis. Moreover, SFN reduced the gene expression of ZEB1, fibronectin, and claudin-1 after 72 h. The expression of β-catenin revealed a time-dependent decrease at the concentration of 40 μM SFN.

CONCLUSION

Downregulation of EMT markers and β-catenin showed accordance with the inhibition of migration. SFN could be a promising drug candidate to reduce metastasis in breast cancer.

Role of Claudin Proteins in Regulating Cancer Stem Cells and Chemoresistance-Potential Implication in Disease Prognosis and Therapy

Claudins are cell–cell adhesion proteins, which are expressed in tight junctions (TJs), the most common apical cell-cell adhesion. Claudin proteins help to regulate defense and barrier functions, as well as differentiation and polarity in epithelial and endothelial cells. A series of studies have now reported dysregulation of claudin proteins in cancers. However, the precise mechanisms are still not well understood. Nonetheless, studies have clearly demonstrated a causal role of multiple claudins in the regulation of epithelial to mesenchymal transition (EMT), a key feature in the acquisition of a cancer stem cell phenotype in cancer cells. In addition, claudin proteins are known to modulate therapy resistance in cancer cells, a feature associated with cancer stem cells. In this review, we have focused primarily on highlighting the causal link between claudins, cancer stem cells, and therapy resistance. We have also contemplated the significance of claudins as novel targets in improving the efficacy of cancer therapy. Overall, this review provides a much-needed understanding of the emerging role of claudin proteins in cancer malignancy and therapeutic management.

DHEAS prevents pro-metastatic and proliferative effects of 17ß-estradiol on MCF-7 breast cancer cells

It is generally assumed that circulating dehydroepiandrosterone sulfate (DHEAS) can be desulfated and further metabolized to estrogen, which is of concern for all patients with estrogen-responsive breast cancer. We addressed this issue by comparing the effects of DHEAS, its desulfated form DHEA, and 17ß-estradiol on human metastatic, estrogen-responsive MCF-7 breast cancer cells. Physiological concentrations of DHEAS promoted phosphorylation of Erk1/2, whereas DHEA and 17ß-estradiol failed to stimulate Erk1/2 phosphorylation, indicating that the sulfated steroid acts as an autonomous hormone. Exposure of MCF-7 cells to 17ß-estradiol stimulated cell proliferation and the expression of pro-metastatic and pro-invasive elements such as claudin-1, matrix metalloproteinase 9 (MMP9), and the CC chemokine ligand 2 (CCL2). In contrast, treatment with DHEAS did not stimulate these responses but prevented all of the actions of 17ß-estradiol, and as a consequence cell migration and invasion were completely inhibited. The results of this study not only challenge the assumption that DHEAS poses a danger as an endogenous source of estrogen, they rather favor the idea that keeping DHEAS levels within a physiological range might be supportive in treating estrogen-responsive breast cancer.

Differential Expression Pattern of Epithelial Mesenchymal Transition Gens: AXL, GAS6, Claudin-1, and Cofilin-1, in Different Stages of Epithelial Ovarian Cancer

BACKGROUND

Epithelial ovarian cancer (EOC), is the fatal form of gynecological cancer. Almost 70% of ovarian cancer patients are detected at an advanced stage (III-IV) with metastases. Epithelial-mesenchymal transition (EMT) is a critical process associated with metastasis. This study investigated the expression levels of AXL, GAS6, Claudin-1, and Cofilin-1, as genes involved in EMT in relation to clinicopathologic features in ovarian cancer patients.

METHODS

In this descriptive study, 78 ovarian epithelial cancer patients were enrolled. Samples were provided by the Iran National Tumor Bank, founded by the Cancer Institute of Tehran University of Medical Sciences in 2017. The expression levels of AXL, GAS6, Claudin-1, and Cofilin-1 genes were investigated in a fresh, frozen tumor sample and normal adjacent tissue by real-time PCR (RT-PCR).

RESULTS

Findings showed a significant relationship between the overexpression of AXL and TNM staging (P=0.03). The expression level of GAS6 decreased in more advanced stages (P=0.01). There is a negative relationship between Cofilin-1 expression level and TNM staging (P=0.002). Claudin-1 expression level was higher in low stages compared with that in high stages (P=0.01). There was no relationship between gene expression levels of target genes with size and grade of the tumor.

CONCLUSION

Given the importance of these genes in EMT, alteration in their expression pattern can contribute to the progression of the disease and distant metastasis of cancer cells. Additionally, knowing the alteration pattern of these genes expression can help to better understanding and prediction of the prognosis of EOC.

Impact of chemotherapy on the expression of claudins and cadherins in invasive breast cancer

The importance of the expression profile of claudins in the molecular classification of breast cancer (BC) is currently under investigation. Claudins, together with cadherins, serve an important role in the epithelial-mesenchymal transition and influence the chemosensitivity of cancer cells. Adjuvant chemotherapy is administered following surgical resection in selected cases of BC. Previous neoadjuvant chemotherapy may change the molecular profile of a tumour and subsequently also its chemosensitivity. In the current study, the expression of claudin-1, −3 and −4, E- and N-cadherin and the standard BC biomarkers [oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and marker of proliferation Ki-67 (Ki-67)] in formalin-fixed, paraffin-embedded sections from 62 patients with invasive BC was analysed using immunohistochemistry prior to and following neoadjuvant chemotherapy. The results revealed increased expression of claudin-1 (P=0.03) and decreased expression of claudin-3 (P=0.005), PR (P<0.001) and Ki-67 (P=0.01) following the neoadjuvant therapy. No significant changes in the expression of ER, claudin-4 or E- and N-cadherin were observed following therapy. Furthermore, an association between the expression of claudin-1 and the standard BC markers (P<0.05) was identified. A high expression of claudin-1 was more frequently observed in the triple-negative BC cohort than in the cohort with positive ER, PR and/or HER2 before (P=0.04) and after chemotherapy (P=0.02). The expression of N-cadherin was associated with the expression of ER, PR, HER2 and tumour grade (P<0.05). A positive association between the expression of claudin-3 and E-cadherin (P=0.005) was observed. No association was found between the expression of E- and N-cadherin. In conclusion, significant changes in the expression of claudin-1 and −3 but not in the expression of claudin-4, E- and N-cadherin were observed in samples taken from patients with BC following chemotherapy. These findings indicate that claudins-1 and −3 serve a role in the response of BC to chemotherapy.

Jorunnamycin A from Xestospongia sp. Suppresses Epithelial to Mesenchymal Transition and Sensitizes Anoikis in Human Lung Cancer Cells

Metastasis is a key driving force behind the high mortality rate associated with lung cancer. Herein, we report the first study revealing the antimetastasis activity of jorunnamycin A, a bistetrahydroisoquinolinequinone isolated from a Thai blue sponge Xestospongia sp. evidenced by its inhibition of epithelial to mesenchymal transition (EMT), sensitization of anoikis, and suppression of anchorage-independent survival in human lung cancer cells. Treatment with jorunnamycin A (0.05-0.5 μM) altered the expression of p53 and Bcl-2 family proteins, particularly causing the down-regulation of antiapoptosis Bcl-2 and Mcl-1 proteins. Under detachment conditions for 12 h, jorunnamycin A-treated cells exhibited diminution of pro-survival proteins p-Akt and p-Erk as well as the survival-promoting factor caveolin-1. Corresponding with the inhibition on the Akt and Erk pathway as well as activation of p53, there was an increase in the epithelial marker E-cadherin and a remarkable decrease of EMT markers and associated proteins including vimentin, snail, and claudin-1. As the loss of anchorage dependence is an important barrier to metastasis, the observed inhibitory effects of jorunnamycin A on the coordinating networks of EMT and anchorage-independent growth emphasize the potential development of jorunnamycin A as an effective agent against lung cancer metastasis.

Polymorphisms in CLDN1 are associated with age and differentiation of triple-negative breast cancer patients

Purpose: Triple-negative breast cancer (TNBC) is a highly heterogeneous disease. It is very important to explore novel biomarkers to better clarify the characteristics of TNBC. It has been reported that polymorphisms in claudin 1 (CLDN1) are associated with risk of several cancers. But till now, there is no report about these polymorphisms and TNBC. Patients and methods: Between January 2004 and December 2013, 267 patients with stage I-III primary TNBC were included in our study. We investigated the association between polymorphisms in CLDN1 gene and clinicopathological characteristics or survival of these patients. We used Haploview 4.2 software to identify Tag single nucleotide polymorphisms (SNPs). MassARRAY MALDI-TOF System was used for genotyping. Results: We found that rs10513846 GA genotype was associated with older age [P=0.013, hazard ratios (HR) = 2.231, 95% confidence interval (CI): 1.186-4.195]. Rs10513846 AA genotype carriers were more likely to develop grade 3 tumors (P=0.005, HR = 2.889, 95% CI: 1.389-6.007). And rs9283658 genotypes were also related to grade, more patients with grade 3 tumors were rs9283658 CC genotype carriers (P=0.023, HR = 0.446, 95% CI: 0.222-0.894). There was no association between polymorphisms in CLDN1 and survival of TNBC patients. After multivariate analysis, tumor size (P=0.021, HR = 3.146, 95% CI: 1.185-8.354) and lymph node status (P<0.001, HR = 10.930, 95% CI: 3.276-36.470) were demonstrated to be independent prognostic factors. Conclusion: We first demonstrated that polymorphisms in CLDN1 gene were associated with age and differentiation of TNBC patients.

Estrogen/GPR30 Signaling Contributes to the Malignant Potentials of ER-Negative Cervical Adenocarcinoma via Regulation of Claudin-1 Expression

Cervical adenocarcinomas are believed to lose estrogen response on the basis of no expression of a nuclear estrogen receptor such as ERα in clinical pathology. Here, we demonstrated that cervical adenocarcinoma cells respond to a physiological concentration of estrogen to upregulate claudin-1, a cell surface molecule highly expressed in cervical adenocarcinomas. Knockout of claudin-1 induced apoptosis and significantly inhibited proliferation, migration, and invasion of cervical adenocarcinoma cells and tumorigenicity in vivo. Importantly, all of the cervical adenocarcinoma cell lines examined expressed a membrane-bound type estrogen receptor, G protein–coupled receptor 30 (GPR30/GPER1), but not ERα. Estrogen-dependent induction of claudin-1 expression was mediated by GPR30 via ERK and/or Akt signaling. In surgical specimens, there was a positive correlation between claudin-1 expression and GPR30 expression. Double high expression of claudin-1 and GPR30 predicts poor prognosis in patients with cervical adenocarcinomas. Mechanism-based targeting of estrogen/GPR30 signaling and claudin-1 may be effective for cervical adenocarcinoma therapy.

Impairment of the Gnα11-controlled expression of claudin-1 and MMP-9 and collective migration of human breast cancer MCF-7 cells by DHEAS

Although dehydroepiandrosterone sulfate (DHEAS) constitutes the most abundant steroid in humans, in-depth investigations of its effects are rather scarce. We address here DHEAS effects on the estrogen receptor-positive metastatic human breast cancer cell line MCF-7. We focus on DHEAS-mediated signaling that might influence expression of claudin-1 and matrix metalloproteinase-9 (MMP-9), both known to be critical factors for migration and invasiveness of various cancers, including breast cancer cells. Physiological concentrations of DHEAS trigger persistent phosphorylation of Erk1/2 in MCF-7 cells. Exposure of these cells for 24 h to 1 μM DHEAS also leads to a significant reduction of claudin-1 expression that cannot be prevented by high concentrations of the steroid sulfatase inhibitor STX64, indicating that desulfation and further conversion of DHEAS to some other steroid hormone is not required for this action. In addition, exposure of MCF-7 cells to the same concentration of DHEAS completely abolishes MMP-9 expression and considerably impairs cell migratory behavior. Abrogation of Gnα11 expression by siRNA prevents the stimulatory effect of DHEAS on Erk1/2 phosphorylation, consistent with a G-protein-coupled receptor being involved in the DHEAS-induced signaling. Nevertheless, Gnα11 also has direct effects that do not depend on DHEAS; thus, when Gnα11 expression is suppressed, expression of claudin-1 and MMP-9 as well as cell migration are significantly reduced. This is the first report demonstrating direct involvement of DHEAS and Gnα11 in the regulation of claudin-1 and MMP-9 expression and migration of MCF-7 cells.

Antrodia camphorata inhibits metastasis and epithelial-to-mesenchymal transition via the modulation of claudin-1 and Wnt/β-catenin signaling pathways in human colon cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Antrodia camphorata (AC) is a well known traditional Chinese medicinal mushroom in Taiwan, has been used to treat various diseases including cancer.

MATERIALS AND METHODS

In this study, we investigated the anti-metastatic and anti-EMT properties of a fermented culture broth of AC in human colon SW480^claudin-1- and metastatic SW620^claudin-1+ cancer cells in vitro.

RESULTS

AC down-regulates claudin-1 and inhibits the proliferation and colony-formation abilities of both SW620^claudin-1+ and SW480^claudin-1- cells. In highly metastatic SW620^claudin-1+ cells, non-cytotoxic concentrations of AC significantly inhibited migration/invasion, accompanied by the down-regulation of MMP-2 and MMP-9 proteins. AC decreased nuclear translocation of Wnt/β-catenin through a GSK3β-dependent pathway. AC consistently inhibited EMT by up-regulating the epithelial and downregulating the mesenchymal marker proteins. In SW480^claudin-1- cells, AC suppressed migration/invasion potentially through the inhibition of the PI3K/AKT/NFκB signaling pathways without altering the expression levels of β-catenin and GSK3β proteins.

CONCLUSION

Altogether, this study demonstrates the anti-metastatic and anti-EMT activities of AC, which may contribute to the development of a chemopreventive agent for colon cancer.

The nucleocytoplasmic translocation and up-regulation of ING5 protein in breast cancer: a potential target for gene therapy

Here, we found that ING5 overexpression resulted in a lower proliferation, reduced glucose metabolism, S arrest, decreased migration and invasion, apoptotic induction, fat accumulation, autophagy, senescence and mesenchymal-epithelial–transition of breast cancer cells. It also suppressed the tumor growth of breast cancer cells by inhibiting proliferation, inducing apoptosis and autophagy. ING5-mediated chemoresistance was positively linked to Akt and NF-κB activation, MRP1 and GST-π overexpression, and FBXW7 hypoexpression. ING5 expression was higher in breast cancer than normal tissue at both mRNA and protein levels. ING5 mRNA expression was positively correlated with relapse- and distant metastasis-free survival rates. Nuclear ING5 expression showed gradual decrease from breast normal tissue, fibroadenoma, adenomatosis, primary to metastatic cancers, while versa for cytoplasmic ING5. Nuclear ING5 expression was negatively correlated with distant metastasis and p53 hypoexpression, while cytoplasmic ING5 expression was positively correlated with tumor size and ER expression. These data suggested that up-regulated expression and nucleocytoplasmic translocation of ING5 protein were observed in breast cancer. The higher expression of nuclear ING5 was inversely linked to worse clinicopathological behaviors of breast cancer by in vivo and vitro reversing aggressive phenotypes. Therefore, it should be employed as a biomarker to indicate the tumorigenesis and aggressiveness of breast cancer, and as a potential target for gene therapy.

The roles of ING5 in gliomas: a good marker for tumorigenesis and a potential target for gene therapy

To elucidate the anti-tumor effects and molecular mechanisms of ING5 on glioma cells, we overexpressed it in U87 cells, and examined the phenotypes and their relevant molecules. It was found that ING5 overexpression suppressed proliferation, energy metabolism, migration, invasion, and induced G₂/M arrest, apoptosis, dedifferentiation, senescence, mesenchymal- epithelial transition and chemoresistance to cisplatin, MG132, paclitaxel and SAHA in U87 cells. There appeared a lower expression of N-cadherin, Twist, Slug, Zeb1, Zeb2, Snail, Ac-H3, Ac-H4, Cdc2, Cdk4 and XIAP, but a higher expression of Claudin 1, Histones 3 and 4, p21, p53, Bax, β-catenin, PI₃K, Akt, and p-Akt in ING5 transfectants. ING5 overexpression suppressed tumor growth of U87 cells in nude mice by inhibiting proliferation and inducing apoptosis. Down-regulated ING5 expression was closely linked to the tumorigenesis and histogenesis of glioma. These data indicated that ING5 expression might be considered as a good marker for the tumorigenesis and histogenesis of gliomas. It might be employed as a potential target for gene therapy of glioma. PI₃K/Akt or β-catenin/TCF-4 activation might be positively linked to chemotherapeutic resistance, mediated by ING5.

The expression of Nectin-4 on the surface of ovarian cancer cells alters their ability to adhere, migrate, aggregate, and proliferate

The cell adhesion molecule Nectin-4 is overexpressed in epithelial cancers, including ovarian cancer. The objective of this study was to determine the biological significance of Nectin-4 in the adhesion, aggregation, migration, and proliferation of ovarian cancer cells. Nectin-4 and its binding partner Nectin-1 were detected in patients' primary tumors, omental metastases, and ascites cells. The human cell lines NIH:OVCAR5 and CAOV3 were genetically modified to alter Nectin-4 expression. Cells that overexpressed Nectin-4 adhered to Nectin-1 in a concentration and time-dependent manner, and adhesion was inhibited by antibodies to Nectin-4 and Nectin-1, as well as synthetic Nectin peptides. In functional assays, CAOV3 cells with Nectin-4 knock-down were unable to form spheroids and migrated more slowly than CAOV3 parental cells expressing Nectin-4. NIH:OVCAR5 parental cells proliferated more rapidly, migrated faster, and formed larger spheroids than either the Nectin-4 knock-down or over-expressing cells. Parental cell lines expressed higher levels of epithelial markers and lower levels of mesenchymal markers compared to Nectin-4 knock-down cells, suggesting a role for Nectin-4 in epithelial-mesenchymal transition. Our results demonstrate that Nectin-4 promotes cell-cell adhesion, migration, and proliferation. Understanding the biology of Nectin-4 in ovarian cancer progression is critical to facilitate its development as a novel therapeutic target.

Expression of ERβ gene in breast carcinoma and the relevance in neoadjuvant therapy

In the present study, we examined the expression of the estrogen receptor β (ERβ) gene in breast cancer and its relevance in neoadjuvant therapy. In total, 120 breast cancer patients who were hospitalized in the Departments of Breast Disease and Medical Oncology served as the subjects of this study. The subjects were diagnosed with breast cancer phase II to phase IIIA, as confirmed by aspiration biopsy and iconography. The patients were divided into two groups in a randomized control manner, with 60 patients in each group. The experimental group was administered the taxotere + epirubicin + cyclophosphamide (TEC) plan for 3–4 cycles of chemotherapy before the modified radical operation of breast cancer. In the control group, no TEC chemotherapy was carried out prior to operation. Instead, the breast lesion was removed directly by operation. After the operation, the IHC method was used to stain the ERβ protein in the lesion tissue. The patients were classified according to whether the basement membrane was broken through; 5 cases had non-infiltrative carcinoma and 115 cases had infiltrative carcinoma. According to the pathology of the lesion, 114 cases had breast ductal carcinoma, 2 cases had mucinous breast carcinoma (of which there were 2 cases combined with ductal carcinoma), and 4 cases had breast lobular carcinoma. The ERβ gene was found to be expressed in normal and breast cancer tissues. When ERβ gene expression was compared before and after the chemotherapy, its expression was significantly increased in breast cancer tissues, which shows a significant statistical difference (P<0.05). In the experimental group, the expression of ERβ gene in carcinoma tissue was significantly lower than that in the control group, and differences were statistically significant (P<0.05). Therefore, expression of the ERβ gene in breast carcinoma tissues was high. The application of adjuvant chemotherapy before the modified radical operation for breast carcinoma can significantly lower the level of ERβ expression. The expression levels of ERβ gene in the carcinoma tissue of the patients can be treated as the evaluation index for neoadjuvant chemotherapy. Regarding targeted therapy and corresponding drug development for breast carcinoma, ERβ can act as one of the specific drug targets.

[The expression of claudins in colonic neoplasms]

AIM

the evaluation of localization claudin-1, -3 and -4 types of cancer and colon polyps.

MATERIAL AND METHODS

The study included 32 colon adenocarcinoma and 86 polyps. Antibody claudin-1; -3 and -4 were used as immunohistochemical markers in this study.

RESULTS

84/118, 64/118, 52/118 reaction with claudin-1, claudin-3 and claudin-4 in cancer and colon polyps had a membrane localization, respectively. In 33 (27.9%) cases was found paradoxical reaction claudin-1; in 50 (42.4%) - a paradoxical reaction claudin-3 in 66 (55.9%) - a paradoxical reaction claudin-4. Among the paradoxical claudin reaction nuclear localization of marker was observed relatively rarely: claudin-3 in 2.5% cases of colon cancer; claudin-4 in 8.5% of colon polyps.

CONCLUSION

Mislocalization claudin-3 to nucleus in colon cancer and mislocalization claudin-4 to nucleus in adenomas of the colon were detected for the first time. The potential reasons for the paradoxical expression are discussed and a review of the literature, related all the alleged mechanisms of this mislocalization is provided.

Claudins in cancer: bench to bedside

The claudin family, in mammals, encoded by at least 27 members of a single ancestral gene, CLDN, is the main constituent as integral membrane proteins of tight junctions. It has been shown that the expression levels of claudins are often decreased or that their expressions are absent in human neoplasias. These findings are consistent with the well-accepted concept that carcinogenesis is accompanied by the disruption or loss of functional tight junctions. In contrast, accumulating data have showed elevated or aberrant expression of claudins in various cancers, indicating specific roles of claudins in tumorigenesis. Importantly, dysregulated claudins play an oncogenic role or conversely have a tumor-suppressive effect depending on target tissues or cell types, and thus, they contribute to tumor development and progression. Although tight junctions are intercellular structures in epithelial cells, specific roles of claudins in cancer are supported by the evidence that TJs are not simple static constituents for establishing cell adhesion structures but are also cell signaling components that have functions in receiving environmental cues and transmitting signals inside cells. Since the expression profile of claudins is associated with patients' outcome and prognosis in several cancer types, an understanding of the expression pattern and subcellular localization of claudins in various pathologies will lead to the establishment of claudins as useful biomarkers for the detection and diagnosis of cancers.

Generation and characterization of a human-mouse chimeric antibody against the extracellular domain of claudin-1 for cancer therapy using a mouse model

Claudin-1 (CLDN-1), an integral transmembrane protein, is an attractive target for drug absorption, prevention of infection, and cancer therapy. Previously, we generated mouse anti-CLDN-1 monoclonal antibodies (mAbs) and found that they enhanced epidermal absorption of a drug and prevented hepatitis C virus infection in human hepatocytes. Here, we investigated anti-tumor activity of a human-mouse chimeric IgG1, xi-3A2, from one of the anti-CLDN-1 mAbs, clone 3A2. Xi-3A2 accumulated in the tumor tissues in mice bearing with human CLDN-1-expressing tumor cells. Xi-3A2 activated Fcγ receptor IIIa-expressing reporter cells in the presence of human CLDN-1-expressing cells, suggesting xi-3A2 has a potential to exhibit antibody-dependent cellular cytotoxicity against CLDN-1 expressing tumor cells. We also constructed a mutant xi-3A2 antibody with Gly, Ser, and Ile substituted with Ala, Asp, and Arg at positions 236, 239, and 332 of the Fc domain. This mutant antibody showed greater activation of Fcγ receptor IIIa and in vivo anti-tumor activity in mice bearing human CLDN-1-expressing tumors than xi-3A2 did. These findings indicate that the G236A/S239D/I332E mutant of xi-3A2 might be a promising lead for tumor therapy.

Homeostatic Signaling by Cell-Cell Junctions and Its Dysregulation during Cancer Progression

The transition of sessile epithelial cells to a migratory, mesenchymal phenotype is essential for metazoan development and tissue repair, but this program is exploited by tumor cells in order to escape the confines of the primary organ site, evade immunosurveillance, and resist chemo-radiation. In addition, epithelial-to-mesenchymal transition (EMT) confers stem-like properties that increase efficiency of colonization of distant organs. This review evaluates the role of cell–cell junctions in suppressing EMT and maintaining a quiescent epithelium. We discuss the conflicting data on junctional signaling in cancer and recent developments that resolve some of these conflicts. We focus on evidence from breast cancer, but include other organ sites where appropriate. Current and potential strategies for inhibition of EMT are discussed.