Claudins and Gastric Cancer: An Overview

High expression of MARVELD3 as a potential prognostic biomarker for oral squamous cell carcinoma

Objectives: Tight junction-associated marvel proteins (TAMP) is a transmembrane protein whose members are associated with tight junctions between cells and epithelial remodeling. MARVEL domain containing 3 (MARVELD3) is one of the members of the TAMP. MARVELD3, as a novel tight junction protein involved in bicellular tight junction assembly, has attracted growing attention in the field of oncology. This study aimed to investigate the prognostic role of MARVELD3 and to determine how it functions in tumorigenesis in oral squamous cell carcinoma (OSCC), thus providing additional data to help the guidance of clinical practice.

Materials and Methods: RNA-seq data and relevant clinical information were obtained from TCGA. Bioinformatics means used in this study included differential gene expression analysis, KM survival curve analysis, univariate and multivariate Cox regression analyses, nomogram analysis, ROC curve analysis, methylation level analysis, gene function enrichment analysis, and immune cell infiltration analysis.

Results:MARVELD3 was significantly higher expressed in OSCC tissue than in normal tissue, and the overall survival of the high expression group was significantly lower than that of the normal group. Univariate and multivariate Cox regression analyses showed that MARVELD3 could serve as an independent contributing factor to poor OSCC prognosis. The nomograms and ROC curves supported the results above. Its expression was negatively correlated with DNA methylation sites. Analysis of PPI networking and gene functional enrichment showed that MARVELD3 was involved in the functional activities of DNA and RNA and was associated with immune cell infiltration.

Conclusion: The high expression of MARVELD3 is associated with poor prognosis in OSCC, and MARVELD3 could be recognized as a novel independent prognostic factor for OSCC.

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.

Claudin-6 increases SNAI1, NANOG and SOX2 gene expression in human gastric adenocarcinoma AGS cells

BACKGROUND

Gastric cancer is a heterogeneous disease associated to deregulated gastric epithelia tight junction barrier function and di novo expression of claudin-6; these changes are associated with epithelial-mesenchymal transition, enhanced invasiveness, metastatic progression, resistance to chemotherapy, and poor prognosis. Gastric cancer stem cells represent a rare population of cells within the tumor implicated in tumor growth and higher tumorigenic capacity. The possible relation between claudin-6 expression and the expression of some markers associated to epithelial mesenchymal transition and cancer stem cells in gastric cancer cells have never been explored.

METHODS AND RESULTS

CD44, CD24, Twist, Villin, DCLK1, claudin-6, NANOG, E-Cadherin, SOX2, and SNAI1 expression was evaluated by immunofluorescence and cytofluorometry in wild type and Claudin-6 transfected AGS cells. Cell migration assays were also performed. Differentially expressed genes and biological processes analysis was performed to determine gene preponderance. The results showed that claudin-6 overexpression enriched the CD44 + /CD24- subpopulation with an overall increase in the expression and the number of CD44 + cells. A significant increase in NANOG, SOX2 and SNAI1 expression and enhanced cell migration was observed in claudin-6 transfected cells. Transcriptome analysis revealed 271 genes involved in enhanced biological processes with only 31 with a significantly p value; thirteen of those genes are closely associated to epithelial mesenchymal transition processes and folding and unfolding processes of proteins in the endoplasmic reticulum.

CONCLUSIONS

The pro-tumorigenic effect of claudin-6 in gastric cancer could be associated to dedifferentiation of epithelial cells and an increase in di novo cancer stem cell genesis.

CircKIF4A promotes non-small cell lung cancer proliferation and metastasis through MiR-1238/CLDN14 axis

As the leading cause of cancer-related death worldwide, non-small-cell lung cancer (NSCLC) is still in need of improved therapeutic strategies. CircKIF4A has been found to be involved in the progression of multiple cancers while its role in NSCLC remains unclear. To investigate the functions of circKIF4A, we assessed the expression of circKIF4A in NSCLC cells and tissues and performed experiments to determine the detailed functions of circKIF4A in NSCLC, including migration and proliferation. We found CircKIF4A expressed more heavily in the cells and tissues of NSCLC patients, and functional studies showed that inhibition of circKIF4A reduced NSCLC cells metastasis and proliferation. Furthermore, we seek to identify the underlying regulatory effect of circKIF4A in NSCLC. Studies revealed that circKIF4A sponged miR-1238 to promote NSCLC progression by up-regulating claudin14 (CLDN14) expression. In conclusion, circKIF4A is a potential diagnostic and therapeutic target in the circKIF4A/miR-1238/CLDN14 axis that plays an important role in NSCLC progression.

Membranous and nuclear staining of CLDN18 in HPV-independent and HPV-associated endocervical adenocarcinomas

OBJECTIVES

A classification system for endocervical adenocarcinoma (ECA) based on high-risk human papillomavirus (HPV) status has been established; however, the immunohistochemical markers distinguishing HPV-independent and HPV-associated ECAs have not been fully described. Here, we aimed to characterize ECA immunopathological features.

METHODS

We evaluated the immunohistochemical profile of CLDN18, CDX2, PAX8, p16, p53, and CEA in 60 ECAs comprising 10 HPV-independent ECAs and 50 HPV-associated ECAs. Both the membranous and nuclear expression levels of CLDN18 were analyzed.

RESULTS

Membranous CLDN18 (CLDN18 [M]) was found to be expressed in the mucinous epithelium of all HPV-independent ECAs, including eight gastric-type ECAs (G-ECAs), one endometrioid ECA, and one clear cell ECA, but no nuclear CLDN18 (CLDN18 [N]) expression was detected in HPV-independent ECAs. Among HPV-associated ECAs, CLDN18 (M) expression levels in intestinal-type (I-ECAs) and usual-type ECAs (U-ECAs) were significantly different from those in invasive stratified mucin-producing (iSMILE) carcinomas (p = 0.036). Positive CLDN18 (M) staining was present in 55.6% (5/9) of intestinal-type and 39.4% (13/33) of usual-type ECAs and was not present in iSMILE ECAs. Silva pattern C cancers expressed higher levels of CLDN18 (M) than Silva pattern A and B cancers (p = 0.004), whereas the CLDN18 (N) expression levels in cancers showing Silva pattern A were significantly higher than those in cancers exhibiting Silva patterns B and C (p < 0.001).

CONCLUSION

Membranous CLDN18 is expressed in ECAs and is particularly frequently expressed in HPV-independent ECAs, and membranous CLDN18 expression has potential as a therapeutic target. Nuclear staining of CLDN18 is a new immunohistochemical marker for diagnosing Silva pattern A HPV-associated ECAs and is associated with a good prognosis. Further studies should investigate the therapeutic and prognostic significance of membranous and nuclear CLDN18 expression and develop a related test that can be implemented in the clinical evaluation of ECAs.

RHOA protein expression correlates with clinical features in gastric cancer: a systematic review and meta-analysis

Background

Gastric cancer (GC) is one of the most fatal cancers worldwide and is generally only detected after it has progressed to an advanced stage. Since there is a lack of comprehensive data on RHOA protein expression of patients with GC, this study utilized a systematic review and meta-analysis to address the limitation. The objective of this meta-analysis was to link GC clinical features with RHOA protein high- vs. low-expressing patients with GC.

Methods

The PubMed and Web of Science were used for a systematic literature review of GC related to RHOA. The included studies were obtained from two literature databases from past to Aug 31, 2021, by searching keywords. This meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The odds ratios (ORs) and 95% confidential intervals (CIs) for clinical features were estimated according to the high and low protein expression levels of RhoA. The mean effect sizes of ORs were obtained using the random-effects and fixed-effects models of meta-analysis. Heterogeneity of the studies was assesed by using statistics: τ², I²; and Q values. The symmetry of funnel plots were inspected for publication bias.

Results

Finally, 10 studies including 1,389 patients with GC (735 RHOA-positive and 654 RHOA-negative) were eligible for our meta-analysis to estimate associations between the protein expression and clinical features (e.g., Union for International Cancer Control [UICC] stage progression, differentiation, Lauren histological classification, and vascular invasion). In our meta-analysis, RHOA positive expression was determined to have a statistically significant association with UICC stage progression (P = 0.02) and poorly differentiated status (P = 0.02). The association between RHOA positivity and Lauren subtypes was not statistically significant (P = 0.07).

Conclusions

This meta-analysis suggested that RhoA protein expression in patients with GC was associated with clinical features: UICC stage progression and poorly differentiated status. Our findings are inconclusive but indicate that high RHOA protein expressing patients with GC could predict advanced UICC stages. A large prospective cohort study is required for validation in future.

Claudin18.2 is a novel molecular biomarker for tumor-targeted immunotherapy

The claudin18.2 (CLDN18.2) protein, an isoform of claudin18, a member of the tight junction protein family, is a highly selective biomarker with limited expression in normal tissues and often abnormal expression during the occurrence and development of various primary malignant tumors, such as gastric cancer/gastroesophageal junction (GC/GEJ) cancer, breast cancer, colon cancer, liver cancer, head and neck cancer, bronchial cancer and non-small-cell lung cancer. CLDN18.2 participates in the proliferation, differentiation and migration of tumor cells. Recent studies have identified CLDN18.2 expression as a potential specific marker for the diagnosis and treatment of these tumors. With its specific expression pattern, CLDN18.2 has become a unique molecule for targeted therapy in different cancers, especially in GC; for example, agents such as zolbetuximab (claudiximab, IMAB362), a monoclonal antibody (mAb) against CLDN18.2, have been developed. In this review, we outline recent advances in the development of immunotherapy strategies targeting CLDN18.2, including monoclonal antibodies (mAbs), bispecific antibodies (BsAbs), chimeric antigen receptor T (CAR-T) cells redirected to target CLDN18.2, and antibody–drug conjugates (ADCs).

Gastric Cancer: Mechanisms, Biomarkers, and Therapeutic Approaches

Gastric cancer (GC) remains one of the most common deadly malignancies worldwide. Recently, several targeted therapeutics for treating unresectable or metastatic GC have been developed. Comprehensive characterization of the molecular profile and of the tumor immune microenvironment of GC has allowed researchers to explore promising biomarkers for GC treatment and has enabled a new paradigm in precision-targeted immunotherapy. In this article, we review established and promising new biomarkers relevant in GC, with a focus on their clinical implications, diagnostic methods, and the efficacy of targeted agents.

Immunoexpression of E-cadherin, CD44 and Claudin 7 in gastric adenocarcinomas

Gastric adenocarcinomas represent frequent malignant tumors in the digestive tract, with a high and constant mortality rate in last decades. The disturbance of the adhesion molecules expression, which normally is essential in maintaining epithelial homeostasis, has a critical role in the initiation and progression of tumors. In this study, we analyzed the immunoexpression of E-cadherin, cluster of differentiation 44 (CD44), and Claudin 7 in 58 cases of gastric adenocarcinomas, in relation to the histopathological parameters of the lesions' aggressiveness. Increased E-cadherin immunoexpression was observed in tubular adenocarcinomas, those of low grade and in stages I-III. CD44 presented high scores in discohesive, hepatoid, tubular, and tubulopapillary adenocarcinomas, those of high grade and in advanced stages. Claudin 7 associated increased scores for tubular, tubulopapillary and micropapillary tumors, those of low grade and mainly in stage I. The markers used in the study can be useful for assessing the aggressiveness of gastric adenocarcinomas, in the context of specific adapted therapy.

Gastric cancer and genomics: review of literature

Gastric cancer (GC) is a major health concern in many countries. GC is a heterogeneous disease stratified by histopathological differences. However, these variations are not used to determine GC management. Next-generation sequencing (NGS) technologies have become widely used, and cancer genomic analysis has recently revealed the relationships between various malignant tumors and genomic information. In 2014, studies using whole-exome sequencing (WES) and whole-genome sequencing (WGS) for GC revealed the entire structure of GC genomics. Genomics with NGS has been used to identify new therapeutic targets for GC. Moreover, personalized medicine to provide specific therapy for targets based on multiplex gene panel testing of tumor tissues has become of clinical use. Recently, immune checkpoint inhibitors (ICIs) have been used for GC treatment; however, their response rates are limited. To predict the anti-tumor effects of ICIs for GC and to select patients suitable for ICI treatment, genomics also provides informative data not only of tumors but also of tumor microenvironments, such as tumor-infiltrating lymphocytes. In therapeutic strategies for unresectable or recurrent malignant tumors, the target is not only the primary lesion but also metastatic lesions, and metastatic lesions are often resistant to chemotherapy. Unlike colorectal carcinoma, there is a heterogeneous status of genetic variants between the primary and metastatic lesions in GC. Liquid biopsy analysis is also helpful for predicting the genomic status of both primary and metastatic lesions. Genomics has become an indispensable tool for GC treatment and is expected to be further developed in the future.