Expressions of Cell Junction Regulatory Proteins and Their Association With Clinicopathologic Parameters in Benign and Malignant Gallbladder Lesions

Reduced occludin expression is related to unfavorable tumor phenotype and poor prognosis in many different tumor types: A tissue microarray study on 16,870 tumors

Occludin is a key component of tight junctions. Reduced occludin expression has been linked to cancer progression in individual tumor types, but a comprehensive and standardized analysis across human tumor types is lacking. To study the prevalence and clinical relevance of occludin expression in cancer, a tissue microarray containing 16,870 samples from 148 different tumor types and 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. Occludin immunostaining was observed in 10,746 (76.6%) of 14,017 analyzable tumors, including 18.9% with weak, 16.2% with moderate, and 41.6% with strong staining intensity. Occludin positivity was found in 134 of 148 tumor categories and was most frequent in adenocarcinomas (37.5-100%) and neuroendocrine neoplasms (67.9-100%), less common in squamous cell carcinomas (23.8-93%) and in malignant mesotheliomas (up to 48.1%), and rare in Non-Hodgkin's lymphomas (1-2%) and most mesenchymal tumors. Reduced occludin staining was linked to adverse tumor features in several tumor types, including colorectal adenocarcinoma (advanced pT stage, p < 0.0001; L1 status, p = 0.0384; absence of microsatellite instability, p < 0.0001), pancreatic adenocarcinoma (advanced pT stage, p = 0.005), clear cell renal cell carcinoma (high ISUP grade, p < 0.0001; advanced pT stage, p < 0.0001; high UICC stage, p < 0.0001; distant metastasis, p = 0.0422; shortened overall or recurrence-free survival, p ≤ 0.0116), papillary renal cell carcinoma (high pT stage, p < 0.0001; high UICC stage, p = 0.0228; distant metastasis, p = 0.0338; shortened recurrence-free survival, p = 0.006), and serous high-grade ovarian cancer (advanced pT stage, p = 0.0133). Occludin staining was unrelated to parameters of tumor aggressiveness in breast, gastric, endometrial, and thyroidal cancer. Our data demonstrate significant levels of occludin expression in many different tumor entities and identify reduced occludin expression as a potentially useful prognostic feature in several tumor entities.

Claudins: from gatekeepers of epithelial integrity to potential targets in hepato-pancreato-biliary cancers

Claudins, a family of tetraspan transmembrane proteins, are critical to the integrity of tight junctions in epithelia and endothelia, influencing cellular processes such as development, differentiation, and apoptosis. Abnormal claudin expression is associated with various malignancies, particularly affecting tissue architecture and potentially facilitating tumor invasion and metastasis. In this comprehensive review, we explore the multifaceted functions of claudins: their expression, specific roles in cancer with a focus on hepato-pancreato-biliary malignancies and highlight their potential as therapeutic targets. We discuss current claudin-targeted therapies, including monoclonal antibodies, antibody-drug conjugates, bispecific T-cell engager and chimeric antigen receptor T-cell therapies. These approaches show promise in pre-clinical and clinical studies, particularly in hepato-pancreato-biliary cancers with large unmet needs. Despite these early signs of efficacy, challenges remain in effectively targeting these proteins due to their structural resemblance and overlapping functions.

Expression and Targeted Application of Claudins Family in Hepatobiliary and Pancreatic Diseases

Hepatobiliary and pancreatic diseases are becoming increasingly common worldwide and associated cancers are prone to recurrence and metastasis. For a more accurate treatment, new therapeutic strategies are urgently needed. The claudins (CLDN) family comprises a class of membrane proteins that are the main components of tight junctions, and are essential for forming intercellular barriers and maintaining cellular polarity. In mammals, the claudin family contains at least 27 transmembrane proteins and plays a major role in mediating cell adhesion and paracellular permeability. Multiple claudin proteins are altered in various cancers, including gastric cancer (GC), esophageal cancer (EC), hepatocellular carcinoma (HCC), pancreatic cancer (PC), colorectal cancer (CRC) and breast cancer (BC). An increasing number of studies have shown that claudins are closely associated with the occurrence and development of hepatobiliary and pancreatic diseases. Interestingly, claudin proteins exhibit different effects on cancer progression in different tumor tissues, including tumor suppression and promotion. In addition, various claudin proteins are currently being studied as potential diagnostic and therapeutic targets, including claudin-3, claudin-4, claudin-18.2, etc. In this article, the functional phenotype, molecular mechanism, and targeted application of the claudin family in hepatobiliary and pancreatic diseases are reviewed, with an emphasis on claudin-1, claudin-4, claudin-7 and claudin-18.2, and the current situation and future prospects are proposed.

Low Expression of Occludin in the Melanoma Patient

BACKGROUND & OBJECTIVE

Malignant melanoma is the fatal cutaneous neoplasm which is curable by the early diagnosis. The expression of occludin protein which is an integral membrane protein is altered in an epithelial-to-mesenchymal transition. Although, recent studies provide sufficient evidence supporting the functional importance of occludin in cancer, the prognostic significance of occludin expression levels in melanoma remains obscure. The aim of this study was to determine occludin expression level and its correlation with clinicopathological features of the patients with melanoma.

METHODS

The occludin mRNA level was compared between paraffin-embedded tissues of 40 patients with melanoma and 10 subjects with normal skin. The quality and quantity of the RNA was determined and occludin expression level was measured using Real-time PCR and ∆∆CT computational technique.

RESULTS

The occludin mRNA level reduced five-fold in the melanoma patients compared to the control group (P=0.000). No significant difference was observed between male and female cases (P=0.533). No significant correlation was observed between occludin mRNA level, mitotic count (P=0.252), and Breslow levels (P=0.171).

CONCLUSION

We can conclude that down-regulation of occludin expression in the patients with melanoma is a hallmark of cancer progression and it might be used as a prognostic factor. No significant correlation was found between occludin gene expression and clinicopathological characteristics including Clark level, Breslow staging, mitotic count, age and gender (P<0.05).

Prognostic Role of Claudin-1 Immunohistochemistry in Malignant Solid Tumors: A Meta-Analysis

Background

Although the correlation between low claudin-1 expression and worse prognosis has been reported, details on the prognostic implications of claudin-1 expression in various malignant tumors remain unclear. The present study aimed to elucidate the prognostic roles of claudin- 1 immunohistochemistry (IHC) in various malignant tumors through a meta-analysis.

Methods

The study included 2,792 patients from 22 eligible studies for assessment of the correlation between claudin-1 expression and survival rate in various malignant tumors. A subgroup analysis based on the specific tumor and evaluation criteria of claudin-1 IHC was conducted.

Results

Low claudin-1 expression was significantly correlated with worse overall survival (OS) (hazard ratio [HR], 1.851; 95% confidence interval [CI], 1.506 to 2.274) and disease-free survival (DFS) (HR, 2.028; 95% CI, 1.313 to 3.134) compared to high claudin-1 expression. Breast, colorectal, esophageal, gallbladder, head and neck, and lung cancers, but not cervical, liver or stomach cancers, were significantly correlated with worse OS. Breast, colorectal, esophageal, and thyroid cancers with low claudin-1 expression were associated with poorer DFS. In the lower cut-off subgroup (< 25.0%) with respect to claudin-1 IHC, low claudin-1 expression was significantly correlated with worse OS and DFS.

Conclusions

Taken together, low claudin-1 IHC expression is significantly correlated with worse survival in various malignant tumors. More detailed criteria for claudin-1 IHC expression in various malignant tumors are needed for application in daily practice.

Effects of claudin-1 downregulation on the physiological processes of gallbladder cancer SGC996 cells

Gallbladder cancer has a high recurrence and mortality rate, with limited treatment options. Therefore, elucidating the underlying molecular mechanisms of this disease would be beneficial to achieve an earlier diagnosis and potentially identify novel treatment targets. Claudin-1 is a tight junction protein associated with the development and prognosis of several types of cancer, and our preliminary studies have demonstrated that claudin-1 expression is elevated in gallbladder cancer tissues. Therefore, the aim of the present study was to investigate the effects of downregulating claudin-1 on the physiological processes of gallbladder cancer cells. The gallbladder cancer SGC996 cell line was transfected with claudin-1-RNA interference lentivirus (LV-CLDN1-RNAi) to downregulate claudin-1 expression, and the downstream effects on cell proliferation, the cell cycle, apoptosis and cell invasion were investigated. Following transfection with LV-CLDN1-RNAi, the results of an MTT assay revealed that downregulating claudin-1 did not affect the proliferation of the SGC996 cells. However, flow cytometry analysis demonstrated that the number of cells arrested in the G₁ phase increased significantly, whereas the amount of cells arrested in the S phase was significantly reduced. Annexin V-APC single-color staining demonstrated that downregulating claudin-1 expression increased the ratio of cell apoptosis, which was confirmed by the results of western blot analysis, in which levels of the pro-apoptotic B-cell lymphoma 2 (Bcl-2)-associated X protein and anti-apoptotic Bcl-2 protein were increased and decreased, respectively. Finally, a Transwell assay indicated that claudin-1 downregulation inhibited cell invasion. Overall, the results from the present study indicated that downregulating claudin-1 expression promoted the apoptosis of gallbladder cancer cells and inhibited cell invasion, indicating that claudin-1 may be involved in the recurrence and metastasis of gallbladder cancer. These insights provide theoretical and experimental foundations for considering claudin-1 as a novel target for the treatment of gallbladder cancer.

Epithelial-to-mesenchymal transition in gallbladder cancer: from clinical evidence to cellular regulatory networks

Gallbladder cancer (GBC), with late diagnosis, rapid disease progression and early metastasis, is a highly aggressive malignant tumor found worldwide. Patients with GBC have poor survival, low curative resection rates and early recurrence. For such a lethal tumor, uncovering the mechanisms and exploring new strategies to prevent tumor progression and metastasis are critically important. Epithelial-to-mesenchymal transition (EMT) has a prominent role in the early steps of tumor progression and metastasis by initiating polarized epithelial cell transition into motile mesenchymal cells. Accumulating evidence suggests that EMT can be modulated by the cooperation of multiple mechanisms affecting common targets. Signaling pathways, transcriptional and post-transcriptional regulation and epigenetic alterations are involved in the stepwise EMT regulatory network in GBC. Loss of epithelial markers, acquisition of mesenchymal markers and dysregulation of EMT-inducing transcription factors (EMT-TFs) have been observed and are associated with the clinicopathology and prognosis of GBC patients. Therefore, EMT may be a detectable and predictable event for predicting GBC progression and metastasis in the clinic. In this review, we will provide an overview of EMT from the clinical evidence to cellular regulatory networks that have been studied thus far in clinical and basic GBC studies.

Alterations in Tumor DNA Are Related to Short Postoperative Survival in Patients Resected for Pancreatic Carcinoma Aimed at Cure

OBJECTIVES

Pancreatic ductal adenocarcinomas (PDACs) are found in more than 85% of patients with pancreatic cancer and with 5-year survival of less than 10%. Effective treatment may be radical surgery, which is hampered by rapid relapse. Therefore, our aim was to compare DNA sequence alterations in patients with short and long survival to evaluate if confirmed DNA alterations predict short postoperative survival.

METHODS

DNA was extracted from tumor tissue from 59 PDAC patients, analyzed for KRAS mutations, and hybridized to 180 K CGH + SNP microarrays and 450 K methylation arrays. Analyses were based on postoperative survival where less than 12 months was considered to be short survival and more than 18 months was considered long survival.

RESULTS

Ninety-three percent of the patients had KRAS mutations in tumor DNA. Great heterogeneity of whole genome DNA sequence alterations were observed among chromosomes within the patient materials. Specific DNA sequence alterations did not directly predict postoperative survival, although short survivors had significantly more and larger DNA amplifications (P < 0.006). Amplifications on chromosome 11 and 21 and deletions on chromosome 2 predicted short postoperative survival (P < 0.03). DNA methylation was not related to survival.

CONCLUSIONS

Highly variable genetic differences among DNA regions in PDAC tumors were demonstrated. Postoperative short survival was related to tumor sequence DNA alterations on chromosome 2, 11, and 21.

Prognostic role of Twist or Snail in various carcinomas: a systematic review and meta-analysis

BACKGROUND

Twist and Snail are considered as key transcriptional repressors of E-cadherin tightly related to epithelial-to-mesenchymal transition (EMT) and cancer progression. Numerous studies have investigated the prognostic value of Twist and Snail. However, the published results were controversial or even opposite. Our article aimed to evaluate the prognostic role of Twist and Snail in patients with cancer.

DESIGN

A comprehensive literature search of PubMed, Embase and Web of Science was conducted. Pooled hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) were assessed to quantify the prognostic role.

RESULTS

The pooled HR with 38 studies for Twist was 2·18 (95% CI: 1·77-2·68, I(2) = 69·8%, P = 0·000) and for Snail with 40 studies was 1·58 (95% CI: 1·33-1·87, I(2) = 70·0%, P = 0·000), suggesting high Twist/Snail expression predicted poor prognosis related to all clinical outcomes. For Twist, the pooled HR for overall survival (OS) was 2·07 (95% CI: 1·63-2·63, I(2) = 72·6%, P = 0·000) and for progression-free/recurrence-free/metastasis-free/disease-free/cancer-free survival (PFS/RFS/MFS/DFS/CFS) was 2·36 (95% CI: 1·76-3·17, I(2) = 65·0%, P = 0·000). For Snail, the pooled HR for OS was 1·63 (95% CI: 1·33-1·99, I(2) = 70·8%, P = 0·000) and for PFS/RFS/MFS/DFS/CFS was 1·54 (95% CI: 1·17-2·02, I(2) = 59·1%, P = 0·001). All of those results were suggesting that high Twist/Snail expression was associated with poor prognosis. Furthermore, when grouped into different types of cancers, the pooled HRs were also calculated for the subgroups. No publication bias was found except studies evaluating all clinical outcomes of Twist (P = 0·006 for Begg's test and 0·006 for Egger's test).

CONCLUSIONS

Elevated Twist or Snail expression in tumour tissue indicated poor prognosis for cancer.