Claudin-4 expression is associated with tumor invasion, MMP-2 and MMP-9 expression in gastric cancer

Claudins-Promising Biomarkers for Selected Gastrointestinal (GI) Malignancies?

Despite recent() improvements in diagnostic ability() and treatment() strategies for patients() with neoplastic disease(), gastrointestinal (GI) cancers(), such() as colorectal, gastric, pancreatic, and oesophageal cancers(), are still common() malignancies and the leading() cause() of cancer() deaths worldwide(), with a high frequency of recurrence and metastasis as well as poor patient() prognosis. There is a link() between the secretion of proteolytic enzymes that degrade the extracellular matrix and the pathogenesis of GI tumours. Recent() findings have focused() on the potential() significance() of selected claudins (CLDNs) in the pathogenesis and prognosis of GI cancers(). Tight junctions (TJs) have been proven to play an important role() in maintaining cell() polarity and permeability. A number of authors have recently() revealed that TJ proteins, particularly() selected CLDNs, are related() to inflammation and the development() of various tumours, including GI malignancies. This review() presents general() characteristics and the involvement() of selected CLDNs in the progression() of GI malignancies, with a focus() on the potential() application() of these proteins in the diagnosis() and prognosis of colorectal cancer() (CRC), gastric cancer() (GC), pancreatic cancer() (PC), and oesophageal cancer() (EC). Our review() indicates that selected CLDNs, particularly() CLDN1, 2, 4, 7, and 18, play a significant() role() in the development() of GI tumours and in patient() prognosis. Furthermore, selected CLDNs may be of value() in the design() of therapeutic() strategies for the treatment() of recurrent tumours.

Twist1‑mediated transcriptional activation of Claudin‑4 promotes cervical cancer cell migration and invasion

Claudin-4, a member of the claudin multigene family, participates in events associated with mesenchymal-like activity of cancerous cells. Claudin-4 expression is upregulated in cervical cancer tissue compared with that in adjoining non-neoplastic tissue. However, the mechanisms that regulate Claudin-4 expression in cervical cancer are poorly understood. Moreover, whether Claudin-4 contributes to the migration and invasion of cervical cancer cells remains unclear. By western blotting, reverse transcription-qPCR, bioinformatics analysis, dual-luciferase reporter assay, chromatin immunoprecipitation assay, wound healing assay and Transwell migration/invasion assay, the present study confirmed that Claudin-4 was a downstream target of Twist1, a helix-loop-helix transcriptional factor, the activity of which has a positive correlation with Claudin-4 expression. Mechanistically, Twist1 directly binds to Claudin-4 promoter, resulting in the transactivation of expression. The depletion of the Twist1-binding E-Box1 domain on Claudin-4 promoter via CRISPR-Cas9 knockout system downregulates Claudin-4 expression and suppresses the ability of cervical cancer cells to migrate and invade by elevating E-cadherin levels and lowering N-cadherin levels. Following activation by transforming growth factor-β, Twist1 induces Claudin-4 expression, thus enhancing migration and invasion of cervical cancer cells. In summary, the present data suggested that Claudin-4 was a direct downstream target of Twist1 and served a critical role in promoting Twist1-mediated cervical cancer cell migration and invasion.

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.

Short-term and bystander effects of radiation on murine submandibular glands

Many patients treated for head and neck cancers experience salivary gland hypofunction due to radiation damage. Understanding the mechanisms of cellular damage induced by radiation treatment is important in order to design methods of radioprotection. In addition, it is crucial to recognize the indirect effects of irradiation and the systemic responses that may alter saliva secretion. In this study, radiation was delivered to murine submandibular glands (SMGs) bilaterally, using a 137Cs gamma ray irradiator, or unilaterally, using a small-animal radiation research platform (SARRP). Analysis at 3, 24 and 48 h showed dynamic changes in mRNA and protein expression in SMGs irradiated bilaterally. Unilateral irradiation using the SARRP caused similar changes in the irradiated SMGs, as well as significant off-target, bystander effects in the non-irradiated contralateral SMGs.

Immunoexpression of Claudin 4 in Gastric Adenocarcinomas

Disturbance of the intercellular adhesion system represents a basic biomolecular mechanism in gastric carcinogenesis. Claudin 4 is member of a protein family involved in maintaining homeostasis and epithelial integrity. In this study, we analyzed the immunoexpression of Claudin 4 in 58 cases of gastric adenocarcinomas, in relation to the main histopathological parameters of aggressiveness, the reactions obtained being evaluated through the intensity of the reactions and the number of positive cells. Positive membranous reactions of Claudin 4 were observed in all cases, in tumor cells and some stromal elements, but in some high grade gastric adenocarcinomas also cytoplasmic immunostaining was present. Claudin 4 high scores were associated with tubular, tubulopapillary and hepatoid adenocarcinomas, of low grade and in early stages, aspects that suggest the usefulness of the marker in evaluating the aggressiveness of gastric epithelial tumors.

Comparison between Heat-Clearing Medicine and Antirheumatic Medicine in Treatment of Gastric Cancer Based on Network Pharmacology, Molecular Docking, and Tumor Immune Infiltration Analysis

Background

Clinical research found that TCM is therapeutic in treating gastric cancer. Clearing heat is the most common method, while some antirheumatic medicines are widely used in treatment as well. To explore the pharmacological mechanism, we researched the comparison between heat-clearing medicine and antirheumatic medicine in treating gastric cancer.

Methods

First, related ingredients and targets were searched, respectively, and are shown in an active ingredient-target network. Combining the relevant targets of gastric cancer, we constructed a PPI network and MCODE network. Then, GO and KEGG enrichment analyses were conducted. Molecular docking experiments were performed to verify the affinity of targets and ligands. Finally, we analyzed the tumor immune infiltration on gene expression, somatic CNA, and clinical outcome.

Results

A total of 31 ingredients and 90 targets of heat-clearing medicine, 31 ingredients and 186 targets of antirheumatic medicine, and 12,155 targets of gastric cancer were collected. Antirheumatic medicine ranked the top in all the enrichment analyses. In the KEGG pathway, both types of medicines were related to pathways in cancer. In the KEGG map, AR, MMP2, ERBB2, and TP53 were the most crucial targets. Key targets and ligands were docked with low binding energy. Analysis of tumor immune infiltration showed that the expressions of AR and ERBB2 were correlated with the abundance of immune infiltration and made a difference in clinical outcomes.

Conclusions

Quercetin is an important ingredient in both heat-clearing medicine and antirheumatic medicine. AR signaling pathway exists in both types of medicines. The mechanism of the antitumor effect in antirheumatic medicine was similar to trastuzumab, a targeted drug aimed at ERBB2. Both types of medicines were significant in tumor immune infiltration. The immunology of gastric tumor deserves further research.

Claudins and Gastric Cancer: An Overview

Simple Summary

Gastric cancer (GC) is one of the most common cancers and the third leading cause of cancer deaths worldwide, with a high frequency of recurrence and metastasis, and a poor prognosis. This review presents novel biological and clinical significance of claudin (CLDN) expression in GC, especially CLDN18, and clinical trials centered around CLDN18.2. It also presents new findings for other CLDNs.

Abstract

Despite recent improvements in diagnostic ability and treatment strategies, advanced gastric cancer (GC) has a high frequency of recurrence and metastasis, with poor prognosis. To improve the treatment results of GC, the search for new treatment targets from proteins related to epithelial–mesenchymal transition (EMT) and cell–cell adhesion is currently being conducted. EMT plays an important role in cancer metastasis and is initiated by the loss of cell–cell adhesion, such as tight junctions (TJs), adherens junctions, desmosomes, and gap junctions. Among these, claudins (CLDNs) are highly expressed in some cancers, including GC. Abnormal expression of CLDN1, CLDN2, CLDN3, CLDN4, CLDN6, CLDN7, CLDN10, CLDN11, CLDN14, CLDN17, CLDN18, and CLDN23 have been reported. Among these, CLDN18 is of particular interest. In The Cancer Genome Atlas, GC was classified into four new molecular subtypes, and CLDN18–ARHGAP fusion was observed in the genomically stable type. An anti-CLDN18.2 antibody drug was recently developed as a therapeutic drug for GC, and the results of clinical trials are highly predictable. Thus, CLDNs are highly expressed in GC as TJs and are expected targets for new antibody drugs. Herein, we review the literature on CLDNs, focusing on CLDN18 in GC.

Effect of KLF17 overexpression on epithelial-mesenchymal transition of gastric cancer cells

Objective

To investigate Krüppel-like factor 17 (KLF17) expression in normal and gastric cancer tissues and cell lines.

Methods

Levels of KLF17 mRNA and protein in GES-1 normal gastric mucosal cells, and NCI-N87, SGC-7901, BGC-823 and HGC-27 gastric cancer cells were analysed by quantitative polymerase chain reaction (qPCR) and western blot. Differences in KLF17 expression between gastric cancer and adjacent tissues were analysed by qPCR and immunohistochemistry. Invasion/migration effects of KLF17 overexpression in BGC-823 and HGC-27 cells were analysed by wound-healing and Transwell chamber assays. Changes in expression of KLF17 and epithelial–mesenchymal transition (EMT)-related genes (matrix metalloproteinase [MMP]-9, vimentin and E-cadherin) were analysed in BGC-823 and HGC-27 cells before and after transfection using qPCR and western blot. Transforming growth factor (TGF)-β1, Smad family member (Smad)2/3 and phosphorylated-Smad2/3 levels in BGC-823 and HGC-27 cells were assessed by qPCR and western blot.

Results

KLF17 expression was lower in gastric cancer versus adjacent tissues, and in gastric cancer cell lines versus GES-1 normal gastric mucosal cells, and was positively correlated with degree of cancer-cell differentiation. Wound-healing and Transwell assays showed decreased migration and invasion ability of BGC-823 and HGC-27 cells transfected to overexpress KLF17. KLF17 overexpression was associated with decreased MMP-9 and vimentin in BGC-823 and HGC-27 cancer cells, and increased KLF17 and E-cadherin. KLF17 overexpression also resulted in decreased levels of TGF-β1 and p-Smad2/3 in BGC-823 and HGC-27 cancer cells.

Conclusion

KLF17 is poorly expressed in gastric cancer tissues and cell lines. KLF17 overexpression might inhibit EMT via the TGF-β/Smad pathway, thereby reducing gastric cancer cell invasion and migration. Therefore, KLF17 may become a novel target for treating gastric cancer.

Intestinal Barrier, Claudins and Mycotoxins

The intestinal barrier is the main barrier against all of the substances that enter the body. Proper functioning of this barrier guarantees maintained balance in the organism. Mycotoxins are toxic, secondary fungi metabolites, that have a negative impact both on human and animal health. It was postulated that various mycotoxins may affect homeostasis by disturbing the intestinal barrier. Claudins are proteins that are involved in creating tight junctions between epithelial cells. A growing body of evidence underlines their role in molecular response to mycotoxin-induced cytotoxicity. This review summarizes the information connected with claudins, their association with an intestinal barrier, physiological conditions in general, and with gastrointestinal cancers. Moreover, this review also includes information about the changes in claudin expression upon exposition to various mycotoxins.

Claudins as biomarkers of differential diagnosis and prognosis of tumors

Claudins are a superfamily of transmembrane proteins, the optimal expression and localization of which are important for the normal physiological function of the epithelium and any imbalance may have pathological consequences. Not only insufficient but also excessive production of claudins in cancer cells, as well as their aberrant localization, equally manifest the formation of a malignant phenotype. Many works are distinguished by contradictory data, which demonstrate the action of the same claudins both in the role of tumor-growth suppressors and promoters in the same cancers. The most important possible causes of significant discrepancies in the results of the works are a considerable variability of sampling and the absence of a consistent approach both to the assessment of the immune reactivity of claudins and to the differential analysis of their subcellular localization. Combined, these drawbacks hinder the histological assessment of the link between claudins and tumor progression. In particular, ambiguous expression of claudins in breast cancer subtypes, revealed by various authors in immunohistochemical analysis, not only fails to facilitate the identification of the claudin-low molecular subtype but rather complicates these efforts. Research into the role of claudins in carcinogenesis has undoubtedly confirmed the potential value of this class of proteins as significant biomarkers in some cancer types; however, the immunohistochemical approach to the assessment of claudins still has limitations, needs standardization, and, to date, has not reached a diagnostic or a prognostic value.

HPV16 infection promotes an M2 macrophage phenotype to promote the invasion and metastasis of esophageal squamous cell carcinoma

OBJECTIVES

High-risk human papillomavirus (HR-HPV) is an important risk factor for esophageal cancer. Macrophages constitute a crucial immune medium for regulating HPV-related tumors; however, the specific regulatory mechanisms remain unknown. Therefore, the purpose of our current study was to investigate the mechanism by which HPV16E6 regulates macrophages to promote the invasion and metastasis of esophageal cancer.

METHODS

HPV16E6 infection was detected by polymerase chain reaction. Immunohistochemistry was used to verify the distribution of tumor-associated macrophages (TAMs) and MMP-9 expression in esophageal squamous cell carcinoma tissues (ESCCs), and cancer adjacent normal tissues (CANs) from Kazakh patients. ESCC cells were transfected with a plasmid over-expressing HPV16E6 and non-contact cocultured with macrophages.

RESULTS

The infection rate of HPV16E6 in Kazakh ESCCs was clearly higher than that in CANs (P < 0.05). The density of CD163-positive TAMs was significantly positively correlated with HPV16E6 infection in ESCCs (P < 0.05). After coculturing macrophages and EC9706 cells transfected with the HPV16E6 plasmid, the phenotype of macrophages transformed into M2 macrophages. The migration and invasion ability of ESCC cells were higher in the HPV16E6-transfected and coculture group than in the HPV16E6 empty vector-transfected and non-cocultured HPV16E6-transfected groups (all P < 0.05). The density of M2-like TAMs in ESCCs was positively correlated with the level of MMP-9 expression. MMP-9 expression in the HPV16E6-ESCC coculture macrophages group was substantially higher than that in controls (all P < 0.05).

CONCLUSIONS

HPV16 infection mediates tumor-associated macrophages to promote ESCC invasion and migration.

Study of the Relationship between MMP-2 and MMP-9 and Her2/neu Overexpression in Gastric Cancer: Clinico- Pathological Correlations

Background:

The relationship between the expressions of matrix metalloproteinases with clinico-pathological data on gastric cancer has been investigated in many countries, but this relationship remains unexplored in Iranian patients. Also, the correlation of the MMPs and the HER-2/neu proto-oncogene with other clinic-pathological variables has been evaluated for several other malignancies, but little effort has been made to shed light on the relationship with gastric cancer.

Methods:

We investigated MMP-2 and MMP-9 expression and HERE-2/neu overexpression in 48 gastric cancer patients referred to Afzalipour Hospital, associated with Kerman Medical University. Immunohistochemistry staining with rabbit polyclonal antibodies was used. Data statistical analysis was done by SPSS software (Version 20.0).

Results:

The mean age was 59, most of the patients were male (79.2%), and the average tumor size was larger than 5 centimeters in its greatest diameter. The majority of tumors were of the intestinal subtype and were located in the pyloric and antrum regions (43.8%). Invasion to muscularis properia was seen in 87.5% of the tumors (T3). MMP-2 and MMP-9 were highly expressed in 58.3% and 50% of cases, respectively, and Her-2/neu positivity was 10.4%. MMP-2, MMP-9 and HER-2 were found to have no relation with any clinicopathological parameters.

Conclusion:

According to the results of this study, MMP-2 and MMP-9 were highly expressed in gastric cancer, but there was no significant association with other clinicopathological variables.

CLDN4 silencing promotes proliferation and reduces chemotherapy sensitivity of gastric cancer cells through activation of the PI3K/Akt signalling pathway

NEW FINDINGS

What is the central question of this study? What is the influence of the interaction between the matrix protein CLDN4 and the PI3K/Akt signalling pathway on tumour progression and chemotherapy sensitivity in gastric cancer? What is the main finding and its importance? Silencing of CLDN4 can promote the growth and proliferation of gastric cancer cells by activating the PI3K/Akt signalling pathway, and thus reduce the sensitivity of gastric cancer cells to chemotherapy.

ABSTRACT

Gastric cancer (GC) is one of the most common cancers worldwide and has a high mortality rate, accompanied by metastasis. Claudins (CLDNs) are major tight-junction proteins that mediate cellular polarity and differentiation. In the present study, we investigated the role of claudin 4 (CLDN4) in modulating cell proliferation and chemotherapeutic sensitivity in GC. Immunohistochemistry and RT-qPCR were initially used to detect the expression of CLDN4 in cancer tissues and adjacent normal tissues collected from GC patients. GC cell lines with the highest and the lowest CLDN4 expression were selected for subsequent experiments. The effects of CLDN4 on GC cell chemosensitivity, proliferation, invasion, migration, apoptosis and tumourigenic capacity were evaluated by conducting gain- and loss-of-function studies of CLDN4. Expression of CLDN4 was significantly decreased in GC tissues and cell lines compared to adjacent normal tissues or gastric epithelial cells. Silencing of CLDN4 increased the extent of PI3K and Akt phosphorylation, and also the proliferation, migration, invasion and tumourigenesis of GC cells; at the same time apoptosis and the sensitivity of GC cells to chemotherapy were reduced. In conclusion, CLDN4 may play a pivotal role in attenuating GC cell proliferation and enhancing sensitivity of GC cells to chemotherapy by inactivating the PI3K/Akt signalling pathway.

Role of extra cellular proteins in gastric cancer progression and metastasis: an update

Background

Gastric cancer (GC) is one of the most common cancers in the world with a high ratio of mortality. Regarding the late diagnosis, there is a high ratio of distant metastasis among GC cases. Despite the recent progresses in therapeutic modalities, there is not still an efficient therapeutic method to increase survival rate of metastatic GC cases.

Main body

Apart from the various intracellular signaling pathways which are involved in tumor cell migration and metastasis, the local microenvironment is also a critical regulator of tumor cell migration. Indeed, the intracellular signaling pathways also exert their final metastatic roles through regulation of extra cellular matrix (ECM). Therefore, it is required to assess the role of extra cellular components in biology of GC.

Conclusion

In the present review, we summarize 48 of the significant ECM components including 17 ECM modifying enzymes, seven extracellular angiogenic factors, 13 cell adhesion and cytoskeletal organizers, seven matricellular proteins and growth factors, and four proteoglycans and extra cellular glycoproteins. This review paves the way of determination of a specific extra cellular diagnostic and prognostic panel marker for the GC patients.

Inhibitory effect of siRNA-Annexin A7 on growth, migration, and invasion in BGC823 cells and gastric cancer xenograftsin nude mice

OBJECTIVE

To explore the inhibitory effect of siRNA-Annexin A7 on growth, migration, and invasion of transplanted gastric cancer in nude mice.

METHODS

The siRNA sequence targeting to human Annexin A7 gene was designed, and based on that a pair of complementary oligonucleotides were synthesized, annealed, and cloned into plasmid pGenesil-1.1 to construct recombinant plasmid siRNA-Annexin A7. Transplanted gastric cancer model was established by injecting s.c. nude mice with human gastric cancer BGC823 cells, and siRNA-Annexin A7 was injected into the tumors formed. The nude mice were observed for clinical manifestation relying on the size and weight of transplanted tumors. The tumor tissue and angiogenesis were examined by pathologic sections. Flow cytometry was used to detect the changes of cell cycle. Western blot and qRT-PCR were used to analyze the expression of PCNA, P27, MMP-2, and TIMP-2.

RESULTS

Both the size and weight of transplanted tumors of nude mice injected with siRNA-Annexin A7 were less than those of control groups (P<0.05). The examination of pathologic sections showed that, compared with in the control group, obvious necrosis of tumor cells was observed in siRNA-Annexin A7 group. The cells in stage S were fewer in siRNA-Annexin A7 group than those in the other two groups, while the cells in stage G0/G1 were much more in siRNA-Annexin A7 group. The results of western blot and qRT-PCR confirmed that the expression of PCNA and MMP-2 was down-regulated, whereas the expression of p27 was up-regulated.

CONCLUSION

Gastric cancer xenografts were established in nude mice with human gastric cancer BGC823 cells. The volume and weight of tumor were decreased after inhibition of Annexin A7 expression in BGC823 cells. Tumor cells were arranged sparsely after inhibition of Annexin A7 expression in BGC823 cells. The siRNA-Annexin A7 inhibits Annexin A7 expression in transplanted gastric cancer of nude mice, and influences the growth, migration, and invasion of tumors by down-regulating the expression of PCNA and MMP-2, as well as up-regulating the expression of p27.

Downregulation of annexin A7 decreases proliferation, migration, and invasion of gastric cancer cells by reducing matrix metalloproteinase 1 and 9 expression

High annexin A7 expression is a potential indicator of lymphatic metastasis and poor prognosis in patients with gastric cancer (GC). The mechanism underlying the effects of annexin A7 on GC cells remains unclear. In patients with GC, primary adenocarcinoma tissues had higher annexin A7 expression than adjacent non-cancerous tissues (P < 0.05). Among three human GC cell lines with high, moderate, and low levels of differentiation, respectively, the cell line with the lowest level of differentiation displayed the highest level of annexin A7 expression. We transfected cells of the human GC cell line BGC823 with short interfering RNAs (siRNAs) targeting annexin A7 and investigated the effects on signaling pathways related to cancer progression by quantitative real-time PCR and western blot. The silencing of endogenous annexin A7 suppressed the proliferation, migration, and invasion abilities of the BGC823 cells. In the cells treated with annexin A7 siRNA, the expression of p16, p21, and p27 was significantly upregulated while that of proliferating cell nuclear antigen (PCNA), cyclin A, cyclin D1, cyclin E1, matrix metalloproteinase-2 (MMP-2), MMP-9, and intercellular cell-adhesion molecule-1 (ICAM-1) was significantly downregulated compared with that in control cells. Our results suggest that the downregulation of endogenous annexin A7 inhibits GC cell proliferation, migration, and invasion by impacting cell cycle regulators and the expression of MMP-1, MMP-2, and ICAM-1. Targeting annexin A7 may represent a valuable strategy for the diagnosis and clinical treatment of GC.

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.

Emodin inhibits the proliferation and invasion of bladder cancer cells via down-regulating Notch1

Emodin exhibits anti-proliferative effects in numerous cancer cell lines via different mechanisms. The present study aimed to study the effects and underlying molecular mechanisms of emodin on bladder cancer cells. We treated two bladder cancer cell lines, T24 and 5637, with different concentrations of emodin (20, 40 and 80 µmol/L) or DMSO (Control). We analyzed the biological effects of emodin on cell growth, invasion, as well as the mRNA and protein expression of Notch1, Jagged1, VEGF, VEGFR2 and MMP2 using Cell Counting Kit-8, transwell, reverse transcription-quantitative PCR and western blot assays. Emodin repressed cell growth, invasion and Notch1 expression in a concentration-dependent fashion. And Notch1 over-expression assay showed that the anti-proliferative and anti-invasive roles of emodin, along with the down-regulated effects on the expression of Notch1, Jagged1, VEGF, VEGFR2 and MMP2 were partially rescued by Notch1 over-expression. In conclusion, Emodin might suppress the progression of bladder cancer via inhibiting the expression of Notch1.

Non-coding RNAs participate in the regulatory network of CLDN4 via ceRNA mediated miRNA evasion

Thousands of genes have been well demonstrated to play important roles in cancer progression. As genes do not function in isolation, they can be grouped into "networks" based on their interactions. In this study, we discover a network regulating Claudin-4 in gastric cancer. We observe that Claudin-4 is up-regulated in gastric cancer and is associated with poor prognosis. Claudin-4 reinforce proliferation, invasion, and EMT in AGS, HGC-27, and SGC-7901 cells, which could be reversed by miR-596 and miR-3620-3p. In addition, lncRNA-KRTAP5-AS1 and lncRNA-TUBB2A could act as competing endogenous RNAs to affect the function of Claudin-4. Our results suggest that non-coding RNAs play important roles in the regulatory network of Claudin-4. As such, non-coding RNAs should be considered as potential biomarkers and therapeutic targets against gastric cancer.Non-coding RNAs can modify the expression of proteins in cancer networks. Here the authors reveal a regulatory network in gastric cancer whereby claudin-4 expression is reduced by specific miRNAs, which are in turn bound by specific lncRNAs acting as competing endogenous RNAs (ceRNAs), resulting in increased claudin-4 expression.

Matrix-metalloproteinases as targets for controlled delivery in cancer: An analysis of upregulation and expression

While commonly known for degradation of the extracellular matrix, matrix metalloproteinases (MMPs) exhibit broad potential for use in targeting of bioactive and imaging agents in cancer treatment. MMPs are upregulated at all stages of expression in cancers. A comprehensive analysis of published literature on expression of all MMP subtypes at the genetic, protein, and activity levels in normal and diseased tissues indicate targeting applicability in a variety of cancers. This expression significantly increases at advanced cancer stages, providing an improved opportunity for controlled release in higher-stage patients. Since MMPs are integral at every stage of metastasis, MMP roles in cancer are discussed with a focus on MMP distribution and mobility within cells and tumors for cancer targeting applications. Several strategies for MMP utilization in targeting - such as matrix degradation, MMP cleavage, MMP binding, and MMP-induced environmental changes - are addressed.

The role of claudins in cancer metastasis

TJs are large intercellular adhesion complexes that maintain cell polarity in normal epithelia and endothelia. During the metastatic process, TJs must be 'loosened' or dismantled in cancer cells to enable migration and dissemination. Diminished TJ integrity must also occur within endothelial cells to allow intravasation and extravasation of cancer cells across endothelial barriers. Claudins are critical components of TJs, forming homo- and heteromeric interactions between the adjacent cells, which have been implicated as key modulators of carcinogenesis and metastasis. Numerous epithelial-derived cancers display altered claudin expression patterns and certain claudins can now be used as biomarkers to predict patient prognosis. Moreover, claudins have been functionally implicated in numerous steps of the metastatic cascade. The distinct roles played by claudins during the cancer progression to metastatic disease are just starting to be elucidated. A more complete understanding of the mechanisms through which claudins augment cancer metastasis is required to develop new therapeutic agents against this family of proteins. In this review, we will summarize the relationship between the claudin expression and clinical outcomes in diverse cancers, discuss tumor intrinisic roles through which claudins regulate metastasis and explore claudin-mediated functions within stromal cells that influence the metastatic process. Finally, we will consider possible strategies for targeting claudins that have the potential to improve the management of metastatic cancer.

Clinicopathological significance of claudin 4 expression in gastric carcinoma: a systematic review and meta-analysis

Background

The prognostic significance of claudin 4 (CLDN4) in patients with gastric cancer (GC) is controversial. This meta-analysis aims to assess the correlation between CLDN4 expression and clinicopathological characteristics and assess the prognostic significance of CLDN4 in GC.

Methods

We searched the PubMed and Embase databases. We performed the meta-analysis with odds ratio (OR), hazard ratio (HR), and 95% confidence interval (CI) as effect values.

Results

Fourteen studies containing 2,106 patients with GC were analyzed. The overall analysis showed that CLDN4 expression was associated with increasing pT category, tumor size, and lymph node metastasis in patients with GC (pT3–T4 vs pT1–T2: OR =1.56, 95% CI =1.13–2.16; P<0.01; large tumor size vs small tumor size: OR =1.64, 95% CI =1.15–2.34; P<0.01; positive lymph node metastasis vs negative lymph node metastasis: OR =1.49, 95% CI =1.12–1.97; P<0.01). CLDN4 expression was associated with histological differentiation (differentiated type vs undifferentiated type: OR =2.90, 95% CI =1.32–6.37; P=0.01; Lauren intestinal type vs diffuse type: OR =3.51, 95% CI =1.48–8.28; P<0.01). CLDN4 expression was also strongly associated with sex and age. This meta-analysis found no significant association between CLDN4 expression and prognosis for overall survival in patients with GC (HR =0.74, 95% CI =0.43–1.27; P=0.28).

Conclusion

Present study indicates that aberrant CLDN4 expression plays an important role in the clinicopathological characteristics of GC.

DDR1 enhances invasion and metastasis of gastric cancer via epithelial-mesenchymal transition

In this study, we investigated the effects of DDR1 on the invasion and metastasis in gastric cancer (GC) via epithelial-mesenchymal transition (EMT). Immunohistochemistry analysis was used to detect DDR1, E-cadherin, and Vimentin expression in GC tissues as well as DDR1 expression in GC cell lines and normal gastric epithelial cells. The relationship between DDR1 expression and EMT in GC cell lines was explored by down and upregulating DDR1 and examining corresponding changes in the expression of EMT-related proteins and in biological characteristics. Furthermore, a nude mice model with a transplantation tumor generating from stably transfected GC cells with DDR1 overexpression was established and performed to further reveal the effects of DDR1 expression on cellular morphology and growth of GC. Our results showed that DDR1 was highly expressed in GC tissues and cell lines compared with adjacent tissues and normal cell line, and its expression was significantly higher in GC having poor differentiation (p < 0.01), advanced depth of wall invasion (p = 0.020), lymph node metastasis (p = 0.0001), liver metastasis (p < 0.01), and high TNM stage (p < 0.01). Western blot analyses revealed that DDR1 overexpression resulted in a significant decrease in the expression of E-cadherin (p < 0.01) and an increase in the expression of Vimentin and Snail (p < 0.01), while knockdown of DDR1 led to opposite outcomes. We further demonstrated that DDR1 overexpression promoted GC cell proliferation (p < 0.05), migration (p < 0.01), and invasion (p < 0.01), and accelerated the growth (p < 0.05) as well as the microvessel formation (p < 0.01) of transplantation tumor in nude mice. Our study establishes that DDR1 enhances invasion and metastasis of gastric cancer via EMT.

Prognostic and clinical significance of claudin-4 in gastric cancer: a meta-analysis

BACKGROUND

The current reports on the association of claudin-4 expression with gastric cancer outcome were inconsistent. Thus, we conducted a meta-analysis to assess the association of claudin-4 expression with the prognosis and clinical parameters more precisely.

METHODS

Systematic searches on PubMed, Embase, and Cochrane Library prior to December 2014 were performed. The pooled hazard ratio (HR) with its 95 % confidence interval (95 %CI) was used to assess the prognostic value of claudin-4 expression with gastric cancer patients, and the pooled odds ratio (OR) with its 95 %CI was used to assess the association with clinical parameters.

RESULTS

Nine studies with a total of 1265 gastric cancer patients were included. Overall, the pooled results showed that over-expression of claudin-4 was associated with a poor survival in gastric cancer patients (HR: 2.01, 95 % CI: 1.62-2.50). Over-expression of claudin-4 was also associated with advanced stage (OR: 1.96, 95 % CI: 1.08-3.56) and lymphoid node metastasis (OR: 1.72, 95 % CI: 1.05-2.81) of gastric cancer patients. No significant publication bias was found among the studies (P > 0.05).

CONCLUSIONS

This meta-analysis shows that over-expression of claudin-4 is associated with progress of gastric cancer and poor prognosis of gastric cancer patients.

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.

Claudin-4 expression in gastric cancer cells enhances the invasion and is associated with the increased level of matrix metalloproteinase-2 and -9 expression

Claudin-4 is a member of a large family of transmembrane proteins known as claudins, which are essential for the formation and maintenance of tight junctions. Our previous studies have revealed that claudin-4 proteins are overexpressed in metastatic gastric cancer. To clarify the roles of claudin-4 in gastric cancer metastasis, human gastric adenocarcinoma (AGS) cells constitutively expressing wild-type claudin-4 were generated. Expression of claudin-4 in AGS cells was found to increase cell invasion and migration, as measured by Boyden invasion chamber assays. Moreover, the claudin-4-expressing AGS cells were found to have increased matrix metalloproteinase (MMP)-2 and -9 expression, indicating that claudin-mediated increased invasion may be mediated through the activation of the MMP protein. Overall, the results suggest that claudin-4 overexpression may promote gastric cancer metastasis through the increased invasion of gastric cancer cells.

Immunoexpression of metalloproteinases 2 and 14 and TIMP-2 inhibitor in main types of primary gastric carcinomas and lymph node metastasis

Metalloproteinase-2 (MMP-2) and -14 (MMP-14) and the tissue inhibitor of metalloproteinases type 2 (TIMP-2) participate in epithelial-mesenchymal transition and tumor progression in many cancers. However, the correlation between these enzymes in gastric cancer and the metastatic potential to their respective lymph node needs to be determined. Here, we evaluated the expression of these enzymes in gastric carcinoma and lymph node metastases and their possible involvement in tumor progression. Histological samples from 83 patients with gastric cancer and their respective lymph nodes were used. MMP-2, MMP-14 and TIMP-2 immunoexpression was scored. TIMP-2 expression in tumor-associated macrophages occurred more frequently than in normal mucosa (P = 0.0128). Female tumor samples presented higher MMP-2 expression (P = 0.0248), while TIMP-2 occurred mainly in patients over 50 years old (P = 0.0034). MMP-2 was higher expressed in primary tumor macrophages than in neoplastic cells (P = 0.0118), and was also seen in macrophages from metastatic-affected lymph nodes of intestinal and diffuse histotypes (P = 0.0006). MMP-2, MMP-14 and TIMP-2 expression in mononuclear cells might be correlated with progression of gastric cancer. MMP-14 production by macrophages appears to be more involved in diffuse gastric cancer progression.

Relationships between abnormal MMP2 expression and prognosis in gastric cancer: a meta-analysis of cohort studies

We carried out this current meta-analysis of relevant cohort studies in an attempt to investigate the relationships between abnormal matrix metalloproteinases-2 (MMP2) expression and gastric cancer (GC) prognosis. A range of electronic databases were searched for relevant articles without any language restrictions: Web of Science (1945-2013), the Cochrane Library Database (Issue 12, 2013), PubMed (1966-2013), EMBASE (1980-2013), CINAHL (1982-2013), and the Chinese Biomedical Database (CBM) (1982-2013). Meta-analysis was conducted using the STATA 12.0 software. Crude hazard ratios (HRs), with 95% confidence intervals (95% CIs), were calculated. Ten clinical cohort studies with a total of 1669 GC patients were included in this meta-analysis. The results of our meta-analysis suggested that MMP2-positive patients display a shorter overall survival (OS) than MMP2-negative patients (HR=1.31, 95% CI=0.98-1.63, p<0.001). Subgroup analysis based on ethnicity revealed that abnormal MMP2 expression was associated with significantly worse OS in patients with GC among both Caucasian and Asian populations (all p<0.05). Our meta-analysis indicated that abnormal MMP2 expression may be strongly correlated with poor prognosis in patients with GC. Thus, MMP2 expression may serve as an independent prognostic factor for GC.

The prognostic role of matrix metalloproteinase 2 in gastric cancer: a systematic review with meta-analysis

PURPOSE

The prognostic role of matrix metalloproteinase 2 (MMP-2) in gastric cancer remains controversial. We systematically reviewed the evidence for assessment of MMP-2 expression in gastric cancer to elucidate this issue.

METHOD

Pubmed, Embase and Web of Science were searched to identify eligible studies to evaluate the association of MMP-2 expression and overall survival and clinicopathological features of gastric cancer.

RESULTS

MMP-2 overexpression was significantly correlated with poor OS of gastric cancer patients (HR 1.92, 95 % CI 1.48-2.48). Subgroup analysis indicated that MMP-2 overexpression had an unfavorable impact on OS in Asian countries (HR 2.23, 95 % CI 1.57-3.17) and European countries (HR 1.43, 95 % CI 1.13-1.80). Furthermore, MMP-2 overexpression was significantly associated with TNM stage (TIII/TIV vs TI/TII: OR 2.17, 95 % CI 1.64-2.87), the depth of invasion (T3/T4 vs T1/T2: OR 2.59, 95 % CI 1.63-4.12), lymph node metastasis (positive vs negative: OR 2.21, 95 % CI 1.69-2.88), and distant metastasis (positive vs negative: OR 4.44, 95 % CI 1.24-15.94).

CONCLUSION

This meta-analysis indicated that MMP-2 overexpression might be a predictive factor for poor prognosis for gastric cancer.

Effect of cyclopamine on expression of VEGF, MMP-2 and MMP-9 in gastric cancer cell line MKN45

AIM: To investigate the effect of cyclopamine on cell apoptosis and expression of vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in gastric cancer cell line MKN45.

METHODS: After MKN45 cells were treated with different concentrations of cyclopamine (7.5, 15, 30, 60, 90, 120 μmol/L) for different durations, cell proliferation was assessed by MTT assay, cell apoptosis and cell cycle progression were determined by flow cytometry, and expression of VEGF, MMP-2 and MMP-9 mRNAs was detected by RT-PCR.

RESULTS: Cyclopamine inhibited the growth of MKN45 cells in a time- and dose-dependent manner. The apoptosis rates of MKN45 cells treated with 30, 60, 90 μmol/L of cyclopamine for 24 h were significantly higher than that of non-treated cells (18.45% ± 0.57%, 39.77% ± 0.61%, 68.52% ± 0.89% vs 2.08% ± 0.49%, all P < 0.05). The percentage of cells in G₀/G₁ phase was increased while that in S phase was decreased in cyclopamine-treated cells, and cell cycle was arrested in G₀/G₁ phase. Treatment with cyclopamine for 24 h decreased the expression levels of VEGF, MMP-2 and MMP-9 mRNA in a dose-dependent manner (all P < 0.05).

CONCLUSION: Cyclopamine inhibits cell proliferation and induces apoptosis in gastric cancer cell line MKN45 via mechanisms possibly associated with down-regulating the expression of tumor invasion-related genes VEGF, MMP-2 and MMP-9.