Claudin 18.2 expression profile in primary tumors and their ovarian metastases: implications for targeted therapy

BACKGROUND

Claudin 18.2 (CLDN18.2), a tight junction protein predominantly expressed in the normal gastric epithelium, has recently emerged as a potential therapeutic target in various solid tumors. Despite growing interest, comprehensive data on CLDN18.2 expression across primary tumors from different organs and their corresponding metastatic lesions remain limited.

METHODS

This study analyzed CLDN18.2 expression in 102 patients with primary adenocarcinomas from various organs and their corresponding ovarian metastatic carcinomas and in 81 cases of primary ovarian mucinous tumors using immunohistochemistry. We evaluated the association of CLDN18.2 expression with clinicopathologic features and survival outcomes.

RESULTS

The highest CLDN18.2 positivity rate was observed in gastric adenocarcinomas (40%, 12/30), followed by cervical adenocarcinomas (20%, 1/5) and colorectal adenocarcinomas (4%, 2/50). Notably, primary ovarian mucinous tumors showed remarkably high expression rates, reaching 77% overall and 100% in mucinous borderline tumors. In contrast, adenocarcinomas of the appendix and breast lacked CLDN18 expression. While CLDN18.2 expression was generally maintained during metastasis, some variations in expression patterns were observed, particularly in gastric cancers (13%, 4/30). Our analysis found no significant correlation between CLDN18.2 expression and overall survival in the patient cohort.

CONCLUSION

The preserved expression of CLDN18.2 in metastatic tumors underscores its potential utility as a target for therapeutic approaches. Our findings emphasize the importance of evaluating CLDN18.2 status in both primary and metastatic tumors to refine therapeutic strategies.

Claudin-1 mediates progression by regulating EMT through AMPK/TGF-β signaling in head and neck squamous cell carcinoma

Claudin-1 (CLDN1), a major component of tight junction complexes in the epithelium, maintains cellular polarity, and plays a critical role in cell-to-cell communication as well as epithelial cell homeostasis. Although the role of CLDN1 has been widely studied in cancer, its role in the progression and the exact regulatory mechanisms, remain controversial. Using next-generation sequencing, we first analyzed the expression profiles of tumor/non-tumor paired tissue in patients with head and neck squamous cell carcinoma (HNSC) from public and local cohorts and found out that CLDN1 is upregulated in tumors compared to normal tissues. Next, its correlation with lymph node metastasis and poor prognosis was validated in the retrospective cohort, which collectively suggests CLDN1 as an oncogene in HNSC. As expected, the knockdown of CLDN1 inhibited invasive phenotypes by downregulating epithelial-to-mesenchymal transition (EMT) in vitro. To ascertain the regulatory mechanism of CLDN1 in HNSC analysis of GO term enrichment, KEGG pathways, and curated gene sets were used. As a result, CLDN1 was negatively associated with AMP-activated protein kinase (AMPK) and positively associated with transforming growth factor-β (TGF-β) signaling. In vitro mechanistic assay showed that CLDN1 inhibited AMPK phosphorylation by regulating AMPK upstream phosphatases, which led to inhibition of Smad2 activity. Intriguingly, the invasive phenotype of cancer cells increased by CLDN1 overexpression was rescued by AMPK activation, indicating a role of the CLDN1/AMPK/TGF-β/EMT cascade in HNSC. Consistently in vivo, CLDN1 suppression significantly inhibited the tumor growth, with elevated AMPK expression, suggesting the novel observation of oncogenic CLDN1-AMPK signaling in HNSC.

Association of β-Catenin, APC, SMAD3/4, Tp53, and Cyclin D1 Genes in Colorectal Cancer: A Systematic Review and Meta-Analysis

Objectives

Accumulating evidence indicates that the expression and/or variants of several genes play an essential role in the progress of colorectal cancer (CRC). The current study is a meta-analysis undertaken to estimate the prognosis and survival associated with CTNNB1/β-catenin, APC, Wnt, SMAD3/4, TP53, and Cyclin D1 genes among CRC patients.

Methods

The authors searched PubMed, EMBASE, and Science Direct for relevant reports published between 2000 and 2020 and analyzed them to determine any relationship between the (immunohistochemically/sequencing-detected) gene expression and variants of the selected genes and the survival of CRC patients.

Results

The analysis included 34,074 patients from 64 studies. To evaluate association, hazard ratios (HRs) were estimated for overall survival (OS) or disease-free survival (DFS), with a 95% confidence interval (CIs). Pooled results showed that β-catenin overexpression, APC mutation, SMAD-3 or 4 loss of expression, TP53 mutations, and Cyclin D1 expression were associated with shorter OS. β-Catenin overexpression (HR: 0.137 (95% CI: 0.131–0.406)), loss of expression of SMAD3 or 4 (HR: 0.449 (95% CI: 0.146–0.753)), the mutations of TP53 (HR: 0.179 (95% CI: 0.126–0.485)), and Cyclin D1 expression (HR: 0.485 (95% CI: 0.772–0.198)) also presented risk for shorter DFS.

Conclusions

The present meta-analysis indicates that overexpression or underexpression and variants of CTNNB1/β-catenin, APC, SMAD3/4, TP53, and Cyclin D1 genes potentially acted as unfavorable biomarkers for the prognosis of CRC. The Wnt gene was not associated with prognosis.

Effect of E-cadherin on Prognosis of Colorectal Cancer: A Meta-Analysis Update

PURPOSE

The effect of E-cadherin on colorectal cancer is still controversial. In order to clarify the effect of E-cadherin on the prognosis and clinicopathological features of colorectal cancer, a meta-analysis was conducted.

METHODS

PubMed, Embase and Cochrane Library were used to collect all relevant literature published before November 2021, and the corresponding data was extracted to analyze the correlation between the expression of E-cadherin and the prognosis and clinicopathological features of colorectal cancer. In addition, the Gene Expression Profiling Interactive Analysis (GEPIA) was used to validate our results.

RESULTS

Fifty-two studies, including 9591 patients, were included in this meta-analysis. According to the meta-analysis, low expression of E-cadherin was significantly associated with shorter overall survival (OS) (hazard ratio [HR] 2.09, 95% confidence interval [CI]1.67-2.62; Z = 6.42, p = 0.000) and disease-free survival (DFS) (HR 2.03, 95% CI 1.71-2.42; Z = 7.95, p = 0.000). In addition, low expression of E-cadherin resulted in higher risk of low differentiation (odds ratio [OR] 0.35, 95% CI 0.25-0.50; p = 0.000), high risk of distant metastasis (OR 0.45, 95% CI 0.35-0.58; p = 0.000), high risk of vascular invasion (OR 0.61, 95% CI 0.45-0.83; p = 0.002), higher risk of lymph node metastasis (OR 0.54, 95% CI 0.42-0.69; p = 0.000), high risk of lymphatic invasion (OR 0.56, 95% CI 0.40-0.80; p = 0.001), high risk of deep infiltration (OR 0.63, 95% CI 0.50-0.80; p = 0.000), later TNM stage (OR 0.60, 95% CI 0.46-0.78; p = 0.000) and late Dukes' stage (OR 0.35,95% CI 0.25-0.49; p = 0.000), but wasn't associated with tumor size (OR 0.90, 95% CI 0.71-1.15; p = 0.406).The results of GEPIA showed that E-cadherin mRNA expression in colorectal cancer tumor tissues and normal tissues had no difference, and had no effect on OS and DFS.

CONCLUSION

Although not supported by GEPIA, our meta-analysis provided abundant data to suggest that low expression of E-cadherin is associated with poor prognosis in colorectal cancer patients and is an important factor influencing adverse clinicopathological features. Therefore, E-cadherin may be used to predict the prognosis of colorectal cancer and provide guidance for clinical treatment.

Effects of 1,2-Dimethylhydrazine on Barrier Properties of Rat Large Intestine and IPEC-J2 Cells

Colon cancer is accompanied by a decrease of epithelial barrier properties, which are determined by tight junction (TJ) proteins between adjacent epithelial cells. The aim of the current study was to analyze the expression of TJ proteins in a rat model of 1,2-dimethylhydrazine (DMH)-induced colorectal cancer, as well as the barrier properties and TJ protein expression of IPEC-J2 cell monolayers after incubation with DMH. Transepithelial electrical resistance and paracellular permeability for sodium fluorescein of IPEC-J2 were examined by an epithelial volt/ohm meter and spectrophotometry. The expression and localization of TJ proteins were analyzed by immunoblotting and immunohistochemistry. In the colonic tumors of rats with DMH-induced carcinogenesis, the expression of claudin-3 and -4 was significantly increased compared to controls. The transepithelial electrical resistance of IPEC-J2 cells increased, while paracellular permeability for sodium fluorescein decreased, accompanied by an increased expression of claudin-4. The increase of claudin-4 in rat colon after chronic DMH exposure was consistent with the acute effect of DMH on IPEC-J2 cells, which may indicate an essential role of this protein in colorectal cancer development.

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.

The relationship between β-catenin and patient survival in colorectal cancer systematic review and meta-analysis

β-catenin is a key component of Wnt signalling, which plays a crucial role in CRC progression. Therefore, a meta-analysis was performed to assess the prognostic value of β-catenin expression in CRC patients. PubMed and Web of Science were searched for relevant publications referring to the association between β-catenin expression and outcome of CRC patients. Review Manager version 5.4 was employed to analysis data from 28 eligible studies (containing 5475 patients). Of these, 6 provided data on DFS, 6 provided data on CSS and 18 reports provided data on OS. High nuclear β-catenin expression was significantly associated with poorer DFS, CSS and OS in patients with CRC whereas, low membranous β-catenin expression was associated to poor OS. In conclusion, β-catenin has prognostic value and potential as a biomarker to stratify patients with CRC. However, further work with high quantity tissue cohorts and patient data is required to confirm this conclusion.

Salivary Duct Carcinoma With Rhabdoid Features-No or Aberrant Expression of E-cadherin and Genetic Changes in CDH1: Immunohistochemical and Genetic Analyses of 17 Cases

Salivary duct carcinoma is a relatively uncommon malignancy of the salivary glands; however, it frequently occurs as a carcinomatous component of carcinoma ex pleomorphic adenoma. We previously reported salivary duct carcinoma with rhabdoid features (SDCRF) as an extremely rare subtype of salivary duct carcinoma, and that it occurred as a salivary counterpart of pleomorphic lobular carcinoma of the breast (PLCB). We collected new cases of SDCRF for this study, in which we examined a total of 17 cases immunohistochemically and genetically. As it is known that PLCB exhibits loss of or aberrant E-cadherin expression and carries nonsense/missense mutations in or deletion of the CDH1 gene, we examined the CDH1 gene status of our SDCRF cases. All of the examined SDCRF cases involved the diffuse proliferation of large ovoid cells with eosinophilic cytoplasm and eccentric nuclei, which displayed reduced cell-cell adhesion. Most cases were positive for pan-cytokeratin, androgen receptor, gross cystic disease fluid protein-15, SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1, and WI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A member 4, whereas they were negative for vimentin. No and decreased/cytoplasmic E-cadherin expression was observed in 11 and 4 of 17 cases, respectively, whereas no and decreased/cytoplasmic β-catenin expression were observed in 10 and 5 of 17 cases, respectively. Among the 11 cases that could be genetically analyzed, a nonsense mutation (1 case), missense mutations (6 cases), and insertions (1 case) were detected in the CDH1 gene. In conclusion, we propose that SDCRF is the salivary counterpart of PLCB due to its morphology and immunophenotype, and the genetic status of CDH1.

Claudin-1 Is a Valuable Prognostic Biomarker in Colorectal Cancer: A Meta-Analysis

Background

Claudin-1 plays an important part in maintaining the mucosal structures and physiological functions. Several studies showed a relationship between claudin-1 and colorectal cancer (CRC), but its prognostic significance is inconsistent. This meta-analysis assessed the prognostic value and clinical significance of claudin-1 in CRC.

Materials and Methods

We retrieved eligible studies from PubMed, Cochrane Library, Embase, and Web of Science databases before February 10, 2020. The hazard ratio (HR) with 95% confidence interval (CI) was applied to assess the correlation between claudin-1 and prognosis and clinical features. Heterogeneity was assessed by the Cochran Q test and I-square (I²), while publication bias was evaluated by the Begg test and Egger test. Test sequence analysis (TSA) was used to estimate whether the included studies' number is sufficient. The stability of the results was judged by sensitivity analysis. Metaregression was utilized to explore the possible covariance which may impact on heterogeneity among studies.

Results

Eight studies incorporating 1704 patients met the inclusion criteria. Meta-analysis showed that the high expression of claudin-1 was associated with better overall survival (HR, 0.46; 95% CI, 0.28–0.76; P = 0.002) and disease-free survival (HR, 0.44; 95% CI, 0.29–0.65; P = 0.003) in CRC. In addition, we found that claudin-1 was related to the better tumor type (n = 6; RR, 0.60; 95% CI, 0.49–0.73; P < 0.00001), negative venous invasion (n = 4; RR, 0.81; 95% CI, 0.70–0.95; P = 0.001), and negative lymphatic invasion (n = 4; RR, 0.83; 95% CI, 0.74–0.92; P = 0.0009).

Conclusion

The increased claudin-1 expression in CRC is associated with better prognosis. In addition, claudin-1 was related to the better tumor type and the less venous invasion and lymphatic invasion.

Effects of supplemental calcium and vitamin D on tight-junction proteins and mucin-12 expression in the normal rectal mucosa of colorectal adenoma patients

The physical gut barrier, comprised of a thick mucus layer and the epithelium, plays an important role in defense against microbes and foreign antigens. Calcium and vitamin D may be involved in maintaining the integrity of the intestinal mucosal barrier, the dysfunction of which may lead to endotoxemia and inflammation, and contribute to colorectal carcinogenesis. We investigated supplemental calcium (1200 mg, daily) and/or vitamin D₃ (1000 IU daily) effects on intestinal barrier function-related biomarkers in a subset of 105 participants from a large colorectal adenoma recurrence chemoprevention clinical trial. We assessed expression of the tight junction proteins claudin-1 (CLDN1), occludin (OCLD), and mucin-12 (MUC12) in the normal-appearing colorectal mucosa using standardized, automated immunohistochemistry and quantitative image analysis. Following 1 year of treatment, in the calcium relative to the no calcium group, the CLDN1, OCLD, and MUC12 expression increased by 14% (P = 0.17), 23% (P = 0.11), and 22% (P = 0.07), respectively. In secondary analyses, the estimated calcium treatment effects were greater among participants with baseline serum 25-OH-vitamin D concentrations below the median value of 22.69 ng/mL (CLDN1: 29%, P = 0.04; OCLD: 36%, P = 0.06; MUC12: 35%, P = 0.05). There were no biomarker expression changes in the vitamin D₃ alone group; however, modest increases were found in the combined calcium/vitamin D₃ group. At baseline, obesity, history of a sessile-serrated adenoma, colorectal MIB-1/Ki-67 expression, and a family history of colorectal cancer were associated with CLDN1, OCLD, and MUC12 expression. Our study supports continued investigation of factors that could affect intestinal mucosal barrier integrity relevant to colorectal carcinogenesis.

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.

Loss of claudin-1 expression induces epithelial-mesenchymal transition through nuclear factor-κB activation in colorectal cancer

OBJECTIVE

The aim of this study was to elucidate the clinicopathological significance and prognostic role of loss of claudin-1 in colorectal cancer (CRC).

METHODS

The correlations between claudin-1 expression and clinicopathological characteristics, including survival rates, were assessed using immunohistochemistry on 260 archival, paraffin-embedded CRC tissues. In addition, the correlations between cludin-1 and nuclear factor-kappa B (NF-κB), epithelial-mesenchymal transition markers and tumor-infiltrating lymphocytes were investigated.

RESULTS

Claudin-1 expression was markedly lost in 42.7% of the 260 CRCs analyzed. Loss of claudin-1 expression significantly correlated with larger tumor size, vascular invasion, higher pT stage, and high metastatic lymph node ratio. In addition, loss of claudin-1 expression significantly correlated with NF-κB activation (P < 0.001), high SNAI (P < 0.001), and low E-cadherin (P < 0.001) expressions. Patients with high immunoscores showed significantly lower rates of claudin-1 expression loss (P = 0.020). In detail, loss of claudin-1 expression were frequently found in CRCs low CD3- and CD8-positive lymphocytes. There were significant correlations between claudin-1 expression loss and poor overall and recurrence-free survivals (P < 0.001 and P < 0.001, respectively).

CONCLUSION

Taken together, our results suggest that the loss of claudin-1 expression significantly correlates with aggressive tumor behaviors, high SNAI expression, lower immunoscore, and poor prognoses.

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.

A novel tumor-based epithelial-to-mesenchymal transition score that associates with prognosis and metastasis in patients with Stage II/III colorectal cancer

It is increasingly appreciated that host factors within the tumor center and microenvironment play a key role in dictating colorectal cancer (CRC) outcomes. As a result, the metastatic process has now been defined as a result of epithelial-mesenchymal transition (EMT). Establishment of the role of EMT within the tumor center and its effect on the tumor microenvironment would be beneficial for prognosis and therapeutic intervention in CRC. The present study assessed five immunohistochemical EMT markers within the tumor center on a 185 Stage II/III CRC patient tissue microarray. In 185 patients with CRC, cytoplasmic snail (HR 1.94 95% confidence interval [CI] 1.15-3.29, p = 0.012) and a novel combined EMT score (HR 3.86 95% CI 2.17-6.86, p < 0.001) were associated with decreased cancer-specific survival. The combined EMT score was also associated with increased tumor budding (p = 0.046), and systemic inflammation (p = 0.007), as well as decreased memory T-cells within the stroma (p = 0.030) and at the invasive margin (p = 0.035). Furthermore, the combined EMT score was associated with cancer-specific survival independent of TNM-stage (HR 4.12 95% CI 2.30-7.39, p < 0.001). In conclusion, a novel combined EMT score stratifies patient's survival in Stage II/III CRC and associates with key factors of tumor metastasis. Therefore, the combined EMT score could be used to identify patients at risk of micrometastases and who may benefit from standard adjuvant therapy, potentially in combination with EMT blockade.

CHIP functions as an oncogene by promoting colorectal cancer metastasis via activation of MAPK and AKT signaling and suppression of E-cadherin

BACKGROUND

The carboxyl terminus of Hsc70-interacting protein (CHIP) is an E3 ubiquitin ligase that plays a controversial role in different cancers, either as a tumor suppressor or a tumor promoter. To date, the exact function and underlying mechanism of CHIP in colorectal cancer (CRC) is not yet clear. Here we aimed to determine whether CHIP could affect the biological behaviors of CRC cells and its underlying mechanisms.

METHODS

Stably transfected CHIP overexpression and depletion DLD-1 and HT-29 cells were established using Lipofectamine 2000. Cell growth was monitored by x-Celligence system. Cell proliferation was detected using CCK-8 and Brdu proliferation assay. Cell apoptosis and cell cycle were detected by flow cytometry analysis. Cell migration and invasion abilities were monitored by x-Celligence system, wound healing assay and transwell assay. In vivo intraperitoneal metastasis assay was performed to investigate the influence of CHIP on the tumor metastasis of CRC cells in nude mice. The expression of ERK, AKT, NF-кB signaling subunits and EMT related proteins were detected by Western blotting. The influence and function of CHIP on the protein expression of CRC cells were also elucidated by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. CRC microarray tissue was analyzed to investigate the CHIP expression and its clinical significance.

RESULTS

CHIP depletion inhibited cell growth, migration and invasion potential of CRC cells, accompanied by downregulation of MAPK and AKT signaling activities and upregulation of E-cadherin. CHIP overexpression dramatically enhanced the migration and invasion abilities, due to the upregulation of MAPK and AKT signaling and downregulation of E-cadherin. The proteomic analysis confirmed that E-cadherin was decreased in CHIP-overexpressing CRC cells. Furthermore, clinical tissue data revealed that CHIP expression was upregulated in CRC samples and was significantly correlated with poor survival of CRC patients. Mechanically, CHIP probably activated the MAPK and AKT signaling, which inactivated GSK-3β. The GSK-3β inactivation, in turn, upregulated Slug and led to E-cadherin downregulation and EMT initiation.

CONCLUSIONS

Our finding suggested that CHIP functions as an oncogene in the migration and metastasis of CRC, and is a potential unfavorable independent predictive biomarker for CRC. CHIP activates the AKT pathway to promote EMT and metastasis in CRC through the CHIP-MAPK/AKT-GSK-3β-Slug-E-cadherin pathways.

Expression of claudin 1, claudin 4, and claudin 7 in colorectal cancer and its relation with CLDN DNA methylation patterns

Altered claudin expression has been described in colon, prostatic, ovarian, and breast carcinoma. However, the role of epigenetic modifications in these genes and their role in colorectal cancer is unknown. We aimed our study to investigate whether claudin protein expression and methylation of CLDN can influence the tumorigenesis of colorectal cancer. A total of 31 patients diagnosed with colorectal carcinoma was used in this study. Immunohistochemical staining was used to study protein expression in both tumor and the adjacent nonneoplastic mucosa of claudin 1, 4, and 7. To detect the DNA methylation pattern of CLDN1, 4, and 7, genomic DNA was extracted from both the tumor and the adjacent nonneoplastic mucosa. Methylation analysis was carried out using bisulfite pyrosequencing. Cell membrane staining intensity of all claudins was found significantly lower in colorectal cancer tissues when compared to paired normal mucosa (p ≤ 0.001). For claudin 4, the percentage of cells staining positively was also significantly reduced (p = 0.04). In normal mucosa, cytoplasm showed no staining for claudins in any patient, whereas in paired colorectal cancer tissues, significant cytoplasmic staining appeared both for claudin 1 (p = 0.04) and claudin 4 (p = 0.01). Tumor samples were significantly hypomethylated in CLDN1 (p < 0.05). In conclusion, our results show that CLDN1 is significantly hypomethylated in tumor samples and that the membrane staining intensity for claudin 1, 4, and 7 is significantly lower in colorectal cancer tissues than in adjacent nonneoplastic tissue. Colorectal cancer cells showed dystopic cytoplasmic location of claudins.

Prognostic and clinical significance of claudin-1 in colorectal cancer: A systemic review and meta-analysis

BACKGROUND

The current reports on the association of claudin-1 expression with colorectal cancer (CRC) result were controversial. Thus, we conducted a meta-analysis to assess the correlation between claudin-1 expression and the clinical parameters and assess the prognostic value of claudin-1 in CRC.

METHODS

Systematic searches on PubMed, Embase, Elsevier, CNKI (China National Knowledge Infrastructure), Wanfang data and Cochrane Library prior to August 2016 were performed. The pooled odds ratio (OR) with its 95% confidence interval (95 %CI) was used to assess association between claudin-1 expression and clinical parameters of CRC patients, and to assess association between claudin-1 expression and the prognostic value of CRC patients.

RESULTS

Eight studies with a total of 1146 CRC patients were included. Overall, the pooled results showed that low expression of claudin-1 was associated with TNM III-IV stage of CRC patients (OR: 1.714, 95%CI: 1.215-2.418, P = 0.002). Low expression of claudin-1 was also associated with a poor survival in CRC patients (one year survival rate: OR: 2.112, 95%CI: 1.028-4.339, P = 0.042; three years survival rate: OR: 1.501, 95%CI: 1.030-2.186, P = 0.035; five years survival rate: OR: 1.794, 95%CI: 1.139-2.439, P = 0.000). Whereas, low expression of claudin-1 is not associated with gender (OR: 1.259, 95%CI: 0.957-1.657, P = 0.100), tumors' differentiation (OR: 1.317, 95%CI: 0.916-1.892, P = 0.137), depth of invasion (OR: 1.016, 95 %CI: 0.701-1.472, P = 0.935) and lymph node metastasis group (OR: 1.286, 95% CI: 0.982-1.684, P = 0.06) of CRC.

CONCLUSIONS

Low expression of claudin-1 is associated with TNM III-IV stage and poor prognosis of CRC patients. Low expression of claudin-1 is not associated with gender, tumors' differentiation depth of invasion and lymph node involvement of CRC patients.

Nuclear expression and/or reduced membranous expression of β-catenin correlate with poor prognosis in colorectal carcinoma: A meta-analysis

BACKGROUND

The differential subcellular localizations of β-catenin (including membrane, cytoplasm, and nucleus) play different roles in the progression of colorectal cancer (CRC). However, the correlation between each subcellular localization of β-catenin and the prognosis of CRC patients remains undetermined.

METHODS

Systematic strategies were applied to search for eligible published studies in the PubMed, Embase, and Web of Science databases. The correlation between each subcellular localizations of β-catenin expression and patients' clinicopathological features or prognosis was analyzed.

RESULTS

Finally, this meta-analysis, including 6238 cases from 34 studies, revealed that β-catenin overexpression in the nucleus (HR: 1.50[95% CI: 1.08-2.10]) or reduced expression of β-catenin in the membrane (HR: 1.33[95% CI: 1.15-1.54]) significantly correlated with lower 5-year overall survival (OS). Conversely, overexpression of β-catenin in the cytoplasm (HR: 1.00[95% CI: 0.85-1.18]) did not show significant association with 5-year OS.

CONCLUSION

This study suggested that β-catenin overexpression in the nucleus or reduced expression in the membrane, but not its overexpression in cytoplasm, could serve as a valuable prognostic predictor for CRC. However, additional large and well-designed prospective studies are required to verify our results.

Salivary duct carcinoma with rhabdoid features: a salivary counterpart of pleomorphic lobular carcinoma of the breast

AIM

To analyse the clinicopathological features and immunohistochemical characteristics of nine cases of salivary duct carcinoma (SDC) with rhabdoid features (SDCRF), representing a new, extremely rare type of salivary gland malignancy.

METHODS AND RESULTS

We analysed 2511 cases of salivary gland tumour, clinicopathologically and immunohistochemically. The incidence of SDCRF was 0.4%. Eight patients were male. The age of patients ranged from 36 years to 85 years (mean, 61 years). SDC arose from the parotid glands and submandibular gland in six and three cases, respectively. Seven cases appeared as a carcinoma component of carcinoma ex pleomorphic adenoma cases. Six patients died of disease. Histologically, diffuse proliferations of non-coherent large ovoid or polygonal carcinoma cells with eosinophilic cytoplasm and eccentric nuclei were observed in all cases; such cytological characteristics were defined as 'rhabdoid features'. Immunohistochemically, all cases were positive for cytokeratin, gross cystic disease fluid protein-15, androgen receptor, and SMARCB1, seven cases were positive for HER2, and two cases were positive for epidermal growth factor receptor. However, all cases were negative for vimentin and myoepithelial markers. Eight cases showed no or aberrant expression of E-cadherin and β-catenin. The results suggest that SDCRF is an extremely rare subtype of SDC, and not a sarcomatoid variant of SDC. SDCRF is histologically unique, and is positive for SDC markers but negative for vimentin, unlike rhabdoid-type carcinomas arising from other organs.

CONCLUSIONS

The morphogenesis of SDCRF is related to no or aberrant expression of cell-cell adhesion molecules. Therefore, SDCRF could be a salivary counterpart to pleomorphic lobular breast carcinoma.

[Еxpression of claudin-1, 3, and 4 in colorectal cancer and polyps]

Claudins are a family of transmembrane tight junctions proteins. It is proven that claudins undergo structural and functional alteration in malignant cells. However, very few researches are pursued on this topic, the data provided by different researchers are controversial. The aim of this study was to evaluate expression of tight junction proteins in cancer and benign polyps of the colon and rectum.

MATERIAL AND METHODS

Specimens of 32 colorectal adenocarcinomas and biopsy specimens of 86 polypoid lesions of the colon and rectum were selected from diagnostic material. Polyps were divided into 6 groups following the 2010 WHO classification of premalignant lesions of the colon and rectum. Immunohistochemical labeling with claudin-1, claudin-3 and claudin-4 antibodies was performed in all cases. We used G. Sheehan et al. (2007) method to evaluate the expression of claudins in neoplasm as well as in adjacent normal mucosa in each slide.

RESULTS

Immunohistochemical staining with claudins antibodies had membranous pattern; claudins expression in adjacent normal mucosa was uniformly close to maximum. Serrated lesions showed the lowest level of expression of claudin-1 among other groups (p<0,05). In the group of adenocarcinomas we found moderate negative correlation between claudin-1 expression level and grade of adenocarcinoma. Claudin-3 expression level was significantly higher in adenocarcinomas compared to serrated lesions (p=0,025) and in conventional adenomas compared to serrated lesions (p=0,034). Expression of claudin-4 was strong in most cases, except for tubular adenomas that showed moderate expression in most cases.

CONCLUSION

We found no statistically significant difference between levels of expression of claudin-1, claudin-3 and claudin-4 expression levels among adenocarcinomas, hyperplastic polyps, sessile serrated adenomas, traditional serrated adenomas, tubular and tubular-villous adenomas. But we detected significant difference after enlargement of the groups. This fact may argue for general development pathway of hyperplastic polyps and sessile serrated adenomas, and of tubular and tubular-villous adenomas. Expression of claudin-1 and claudin-3 revealed difference of serrated lesions from conventional adenomas and adenocarcinomas, that confirms conception of independent «serrated» pathway of cancerogenesis.

[Impact of preoperative drug therapy on adhesion molecule expression in colorectal cancer liver metastases]

OBJECTIVE

To study E-cadherin and β-catenin expression in colorectal cancer (CRC) liver metastases in order to assess the impact of different drug therapy regimens on the adhesive properties of tumor cells.

MATERIAL AND METHODS

Intraoperative metastatic CRC samples from patients who had received preoperative cytotoxic chemotherapy or combined cytotoxic and targeted anti-VEGF (vascular endothelial growth factor) therapy were immunohistochemically examined using antibodies to E-cadherin and β-catenin. A comparison group consisted of patients who had not received drug therapy.

RESULTS

Combined therapy with cytotoxic and anti-VEGF agents was shown to result in a significant increase in the number of cases of normal membrane localization of E-cadherin as compared with control (p = 0.00043) and cytotoxic therapy-alone (p = 0.01) groups. A comparison of β-catenin levels in three patient groups revealed no significant differences, but addition of an anti-VEGF agent caused some decrease in the number of cases of abnormal nuclear localization of the protein as compared to both the control group and the cytotoxic therapy groups. The comparison of E-cadherin and β-catenin localization in tumor cells showed that a combination of normal E-cadherin membrane localization and β-catenin membrane-cytoplasmic expression prevailed in the combined therapy group compared to the control (p = 0.009) and cytotoxic therapy (p = 0.04) groups.

CONCLUSION

The addition of a targeted anti-VEGF agent to the drug therapy of metastatic CRC has a positive impact on the cadherin-catenin complex, leading to increased intercellular contacts and suppressed β-catenin functioning as a transcription factor that enhances tumor cell proliferation.

B-cell lymphoma 2 and β-catenin expression in colorectal cancer and their prognostic role following surgery

The prognosis of colorectal cancer depends on the stage of the disease. However, even within the same stage there may be different outcomes in terms of recurrence and survival. Therefore, it is clear that as well as pathological stage, novel biomarkers that are capable of improving risk stratification and therapeutic decision-making are required. The present study aimed to evaluate the potential roles of two previously proposed biomarkers of tumour status: B-cell lymphoma 2 (Bcl-2) and β-catenin. A total of 412 patients undergoing surgery for primary colorectal cancer were studied. Tumour specimens of the patients were collected, fixed and processed for immunohistochemical detection of Bcl-2 and β-catenin. The data were then analyzed in relation to disease-free survival and overall survival. Pathological stage was the only variable that was significantly correlated with both disease-free and overall survival. The expression levels of neither Bcl-2 nor β-catenin were able to accurately predict prognosis. However, there was a clear association between nuclear β-catenin expression levels and disease-free survival in the three tumour stages. There was an increased hazard ratio in stage I and II nuclear β-catenin positive tumours, whereas there was a marked decrease in risk in stage III positive tumours. A similar effect was also observed with regards to overall survival, however this finding was not significant. The results of the present study suggest that conventional pathological tumour staging is the only accurate prognostic method. Neither Bcl-2 or β-catenin were shown to be useful biomarkers for the prognosis of colorectal cancer. However, the heterogeneous behaviour of nuclear β-catenin expression in the various tumour stages may indicate a possible role in predicting the response of patients to chemotherapy. Therefore, nuclear β-catenin expression may be a biomarker for the prediction of improved responses to chemotherapy.

Loss of tight junction proteins (Claudin 1, 4, and 7) correlates with aggressive behavior in colorectal carcinoma

BACKGROUND

Tight junction proteins in the cell organize paracellular permeability and they play a critical role in apical cell-to-cell adhesion and epithelial polarity. Claudins are major integral membrane proteins of tight junctions, especially Claudin 1, 4, and 7, which are known as the impermeability Claudins. In this study, we investigated the importance of loss of Claudin 1, 4, and 7 expression, and their relation to tumor progression in colorectal cancer patients.

MATERIAL/METHODS

Loss of Claudin 1, 4, and 7 expression was examined by immunohistochemical method in 70 patients diagnosed with colorectal cancer. Cases with loss of Claudin expression in <1/3 of tumor cells were classified as mild loss, whereas cases with loss of Claudin expression ³1/3 of tumor cells were classified as moderate-to-marked loss in order to evaluate the relation between loss of Claudin 1, 4, and 7 expression and clinicopathologic data.

RESULTS

The severe suppression of Claudin 1, 4, and 7 expression was found to be significantly related to the depth of tumor invasion, positive regional lymph nodes, histological grade, lymphovascular invasion, perineural invasion, and lymphocytic response. Additionally, severity of loss in Claudin 4 expression was found to have a relation with distant metastasis.

CONCLUSIONS

Claudin 1, 4, and 7 are important building blocks of paracellular adhesion molecules. Their decreased expression in colorectal cancer seems to have critical effects on cell proliferation, motility, invasion, and immune response against the tumor.

Prognostic Significance of β-Catenin, E-Cadherin, and SOX9 in Colorectal Cancer: Results from a Large Population-Representative Series

Robust biomarkers that can precisely stratify patients according to treatment needs are in great demand. The literature is inconclusive for most reported prognostic markers for colorectal cancer (CRC). Hence, adequately reported studies in large representative series are necessary to determine their clinical potential. We investigated the prognostic value of three Wnt signaling-associated proteins, β-catenin, E-cadherin, and SOX9, in a population-representative single-hospital series of 1290 Norwegian CRC patients by performing immunohistochemical analyses of each marker using the tissue microarray technology. Loss of membranous or cytosolic β-catenin and loss of cytosolic E-cadherin protein expression were significantly associated with reduced 5-year survival in 903 patients who underwent major resection (722 evaluable tissue cores) independently of standard clinicopathological high-risk parameters. Pre-specified subgroup analyses demonstrated particular effect for stage IV patients for β-catenin membrane staining (P = 0.018; formal interaction test P = 0.025). Among those who underwent complete resection (714 patients, 568 evaluable), 5-year time-to-recurrence analyses were performed, and stage II patients with loss of cytosolic E-cadherin were identified as an independent high-risk subgroup (P = 0.020, formal interaction test was not significant). Nuclear β-catenin and SOX9 protein, regardless of intracellular location, were not associated with prognosis. In conclusion, the protein expression level of membranous or cytosolic β-catenin and E-cadherin predicts CRC patient subgroups with inferior prognosis.

Expression of claudin-7 and loss of claudin-18 correlate with poor prognosis in gastric cancer

BACKGROUND

The purpose of this study was to evaluate the expression of claudin-3, claudin-7, and claudin-18 in gastric cancer and to determine the significance of these proteins for patient outcome.

MATERIALS AND METHODS

A total of 134 samples were obtained from surgically resected specimens from patients who were diagnosed with gastric carcinoma at a single institution. Paraffin tissue sections from tissue microarray blocks were examined with immunohistochemistry for the expression of claudin-3, claudin-7, and claudin-18.

RESULTS

In normal gastric tissues, positive immunoreactivity was detected for claudin-18 but not for claudin-3 or claudin-7. Claudin-3 and claudin-7 were expressed in 25.4% and 29.9% of the gastric cancer tissues, respectively. However, 51.5% of gastric cancer tissues exhibited reduced expression of claudin-18. Claudin-7 expression was significantly lower in cases with diffuse histologic type and positive lymphatic invasion. There was a significant inverse correlation between claudin-18 expression and perineural invasion. In the survival analysis, the overall survival time was shorter in patients with claudin-7 expression than in those without claudin-7 expression. However, the overall survival was longer in patients with claudin-18 expression than in those without claudin-18 expression.

CONCLUSIONS

Our data suggest that the up-regulation of claudin-3 and claudin-7 and the down-regulation of claudin-18 may play a role in the carcinogenesis of gastric cancer. Furthermore, the expression of claudin-7 and the loss of claudin-18 may be independent indicators of a poor prognosis in patients with gastric cancer.

Emerging roles of claudins in human cancer

Claudins are major integral membrane proteins of tight junctions. Altered expression of several claudin proteins, in particular claudin-1, -3, -4 and -7, has been linked to the development of various cancers. Although their dysregulation in cancer suggests that claudins play a role in tumorigenesis, the exact underlying mechanism remains unclear. The involvement of claudins in tumor progression was suggested by their important role in the migration, invasion and metastasis of cancer cells in a tissue-dependent manner. Recent studies have shown that they play a role in epithelial to mesenchymal transition (EMT), the formation of cancer stem cells or tumor-initiating cells (CSCs/TICs), and chemoresistance, suggesting that claudins are promising targets for the treatment of chemoresistant and recurrent tumors. A recently identified claudin-low breast cancer subtype that is characterized by the enrichment of EMT and stem cell-like features is significantly associated with disease recurrence, underscoring the importance of claudins as predictors of tumor recurrence. The critical role of epigenetic mechanisms in the regulation of claudin expression indicates the possible application of epigenetic therapy to target claudins. A better understanding of the emerging role of claudins in CSC/TICs and chemoresistance may help to develop therapies against recurrent cancers.

Regulation of the Epithelial-Mesenchymal Transition by Claudin-3 and Claudin-4

The mechanisms that control intracellular adhesion are central to the process of invasion and metastasis. Claudin-3 (CLDN3) and claudin-4 (CLDN4) are major structural molecules of the tight junctions that link epithelial cells. Our prior work has demonstrated that knockdown of the expression of either CLDN3 or CLDN4 produces marked changes in the phenotype of ovarian carcinoma cells including increases in growth rate in vivo, migration, invasion, metastasis, and drug resistance, similar to those produced by the epithelial-to-mesenchymal transition (EMT). We postulated that these changes may result from the ability of CLDN3 or CLDN4 to suppress EMT. In this study we found that knockdown of either CLDN3 or CLDN4 increased cell size and resulted in flattened morphology. While knockdown of CLDN3 or CLDN4 did not alter the expression of vimentin, it significantly down-regulated the level of E-cadherin and up-regulated N-cadherin expression. Conversely, over-expression of CLDN3 or CLDN4 in a cell line that does not express endogenous CLDN3 or CLDN4 decreased N-cadherin expression. Re-expression of E-cadherin in the CLDN3 or CLDN4 knockdown cells reduced migration, invasion and tumor growth in vivo. Loss of either CLDN3 or CLDN4 resulted in activation of the PI3K pathway as evidenced by increased Akt phosphorylation, elevated cellular PIP3 content and PI3K activity as well as up-regulation of the mRNA and protein levels of the transcription factor Twist. Taken together, these findings suggest that CLDN3 and CLDN4 function to sustain an epithelial phenotype and that their loss promotes EMT.

β-catenin overexpression in the nucleus predicts progress disease and unfavourable survival in colorectal cancer: a meta-analysis

BACKGROUND

β-catenin plays a key role in the progression of colorectal cancer (CRC). However, its prognostic significance for patients with CRC remains controversial.

METHODOLOGY

Identical search strategies were used to search relevant literatures in the PubMed, Embase and Web of Science databases. The correlation between β-catenin expression and clinicopathological features and prognosis was analyzed.

PRINCIPAL FINDINGS

A total of 18 studies met the inclusion criteria, which comprised 3665 cases. Meta-analysis suggested that β-catenin overexpression in the nucleus was significantly associated with disease free survival (DFS) (n = 541 in 3 studies; HR = 1.87, 95% CI: 1.28-2.71; Z = 3.26; P = 0.001) and overall survival (OS) for CRC patients (n = 2630 in 10 studies; HR = 1.55, 95% CI: 1.12-2.14; Z = 2.62; P = 0.009). However, there was no significant association between β-catenin expression in the cytoplasm and OS (n = 1327 in 3 studies; HR = 1.04, 95% CI: 0.88-1.24, Z = 0.46, P = 0.643). The combined odds ratio (OR) of β-catenin in the nucleus indicated that β-catenin overexpression was associated with advanced stage CRC (n = 950 in 7 studies; OR = 0.71, 95% CI: 0.53-0.94; Z = 2.35; P = 0.019) and metastasis of CRC (n = 628 in 5 studies; OR = 0.49, 95% CI: 0.25-0.96, Z = 2.06, P = 0.039). β-catenin overexpression in the nucleus had no correlation with the tumor site (colon or rectum), differentiation grade, lymph node status or depth of invasion. The pooled ORs were 1.09 (95% CI: 0.41-2.91, Z = 0.18, P = 0.856), 1.27(95% CI: 0.76-2.10, Z = 0.92, P = 0.357), 0.71(95% CI: 0.46-1.09, Z = 1.58, P = 0.115) and 0.82(95% CI: 0.4-1.68, Z = 0.53, P = 0.594).

CONCLUSIONS

This study showed that β-catenin overexpression in the nucleus, rather than in the cytoplasm, appeared to be associated with progress disease and a worse prognosis for CRC patients.

Tight junction proteins claudin-3 and claudin-4 control tumor growth and metastases

The extent of tight junction (TJ) formation is one of many factors that regulate motility, invasion, and metastasis. Claudins are required for the formation and maintenance of TJs. Claudin-3 (CLDN3) and claudin-4 (CLDN4) are highly expressed in the majority of ovarian cancers. We report here that CLDN3 and CLDN4 each serve to constrain the growth of human 2008 cancer xenografts and limit metastatic potential. Knockdown of CLDN3 increased in vivo growth rate by 2.3-fold and knockdown of CLDN4 by 3.7-fold in the absence of significant change in in vitro growth rate. Both types of tumors exhibited increase in birth rate as measured by Ki67 staining and decrease in death rate as reflected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. Knockdown of either claudin did not alter expression of other TJ protein but did reduce TJ formation as measured by transepithelial resistance and paracellular flux of dextran, enhance migration and invasion in in vitro assays, and increase lung colonization following intravenous injection. Knockdown of CLDN3 and CLDN4 increased total lung metastatic burden by 1.7-fold and 2.4-fold, respectively. Loss of either CLDN3 or CLDN4 resulted in down-regulation of E-cadherin mRNA and protein, increased inhibitory phosphorylation of glycogen synthase kinase-3β (GSK-3β), and activation of β-catenin pathway signaling as evidenced by increases in nuclear β-catenin, the dephosphorylated form of the protein, and transcriptional activity of β-catenin/T-cell factor (TCF). We conclude that both CLDN3 and CLDN4 mediate interactions with other cells in vivo that restrain growth and metastatic potential by sustaining expression of E-cadherin and limiting β-catenin signaling.

Alteration of the E-Cadherin/β-Catenin Complex Is an Independent Poor Prognostic Factor in Lung Adenocarcinoma

Background

Epithelial-mesenchymal transition (EMT) is an important step in the invasion and progression of cancer and in the development of chemoresistance by cancer cells.

Methods

To address the clinical significance of the EMT pathway in lung adenocarcinoma and the association of the pathway with histological subtype, we examined 193 surgically resected lung adenocarcinoma samples for the expression of representative EMT-related proteins (E-cadherin, β-catenin, and vimentin) by immunohistochemistry. Histological subtypes were classified according to the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification. The results for EMT-related protein expression were analyzed for correlation with clinicopathological features and with survival.

Results

The loss of E-cadherin expression and aberrant β-catenin expression were significantly associated with larger tumor size, pleural invasion, lymphatic/vascular invasion, and advanced pathological stage (p<0.05). The alteration of the E-cadherin/β-catenin complex was least frequently observed in the lepidic-predominant group, but these associations were not statistically significant. In the multivariate analysis, altered E-cadherin/β-catenin complex expression was found to be an independent poor prognostic factor (p=0.017; hazard ratio, 1.926; 95% confidence interval, 1.119 to 3.314).

Conclusions

The alteration of the expression of the E-cadherin/β-catenin complex was associated with aggressive tumor behavior in lung adenocarcinoma.

Expression of β-catenin and E- and N-cadherin in human brainstem gliomas and clinicopathological correlations

Brainstem gliomas are usually associated with serious dysfunction and poor prognosis especially for diffuse intrinsic brainstem gliomas; however, the reasons are still unclear. Some clinical studies have suggested that the invasive ability may be different among brainstem gliomas, and the dysfunction of β-catenin and E- and N-cadherin appears to be connected with tumor invasion and progression. In this study, the expression of β-catenin and E- and N-cadherin was detected in 40 brainstem glioma samples using immunochemistry and was further analyzed in 18 samples using reverse transcription-polymerase chain reaction. The clinicopathological characteristics were also analyzed. The results show that there was no obvious staining for E-cadherin, but weak expression at the messenger RNA (mRNA) level could be seen in a few samples. The protein and mRNA expression levels of β-catenin and N-cadherin were significantly associated with the pathological grades of brainstem gliomas. No significant differences in the expression levels of β-catenin and N-cadherin were observed for age, sex, location or diffuse growing pattern. The overall survival of patients with low β-catenin expression was longer than that with high β-catenin expression, and there was a trend toward increased expression of N-cadherin with shorter survival; however, both of them had no statistical differences. These results demonstrate that expression of β-catenin and N-cadherin is associated with the malignant progression of brainstem gliomas but not correlated with the diffuse and invasive growing pattern. β-catenin and N-cadherin are potential therapeutic targets and prognostic markers for brainstem glioma, which need to be validated in a larger patient cohort.

Combined loss of E-cadherin and aberrant β-catenin protein expression correlates with a poor prognosis for small intestinal adenocarcinomas

Small intestinal adenocarcinomas (SIACs) are rare, and their molecular pathogenesis is largely unknown. To define the roles of E-cadherin and β-catenin, we performed immunohistochemistry for E-cadherin and β-catenin in 194 surgically resected SIACs with tissue microarrays and compared the data with clinicopathologic factors, including survival rates of patients with SIAC. Loss of E-cadherin expression and aberrant β-catenin expression were observed in 41.8% (81/194 cases) and 40.7% (79/194 cases) of SIACs, respectively. Combined loss of E-cadherin and aberrant β-catenin expression was observed in 24.2% (47/194 cases) of SIACs, and this feature was most frequently observed in mucinous adenocarcinomas and signet ring cell carcinomas (P < .001), poorly differentiated and undifferentiated carcinomas (P < .001), and tumors with advanced pT classification (P = .03). Survival times for patients with SIAC with both loss of E-cadherin and aberrant β-catenin expression (median, 13.9 months) were significantly shorter than those for patients without aberrant expression of both proteins (49.9 months), as determined by univariate (P < .001) and multivariate (P = .01) analyses. In conclusion, loss of E-cadherin and aberrant β-catenin expression correlate with poorly differentiated tumors, advanced T classification, and decreased patient survival time; therefore, it could be a prognostic factor in patients with SIAC.

Claudin-3 and claudin-4 regulate sensitivity to cisplatin by controlling expression of the copper and cisplatin influx transporter CTR1

Claudin-3 (CLDN3) and claudin-4 (CLDN4) are the major structural molecules that form tight junctions (TJs) between epithelial cells. We found that knockdown of the expression of either CLDN3 or CLDN4 produced marked changes in the phenotype of ovarian cancer cells, including an increase in resistance to cisplatin (cDDP). The effect of CLND3 and CLDN4 on cDDP cytotoxicity, cDDP cellular accumulation, and DNA adduct formation was compared in the CLDN3- and CLDN4-expressing parental human ovarian carcinoma 2008 cells and CLDN3 and CLDN4 knockdown sublines (CLDN3KD and CLDN4KD, respectively). Knockdown of CLDN3 or CLDN4 rendered human ovarian carcinoma 2008 cells resistant to cDDP in both in vitro culture and in vivo xenograft model. The net accumulation of platinum (Pt) and the Pt-DNA adduct levels were reduced in CLDN3KD and CLDN4KD cells. The endogenous mRNA levels of copper influx transporter CTR1 were found to be significantly reduced in the knockdown cells, and exogenous expression of CTR1 restored their sensitivity to cDDP. Reexpression of an shRNAi-resistant CLDN3 or CLDN4 up-regulated CTR1 levels, reversed the cDDP resistance, and enhanced TJ formation in the knockdown cells. Baseline copper (Cu) level, Cu uptake, and Cu cytotoxicity were also reduced in CLDN3KD and CLDN4KD cells. Cu-dependent tyrosinase activity was also markedly reduced in both types of CLDN knockdown cells when incubated with the substrate l-DOPA. These results indicate that CLDN3 and CLDN4 affect sensitivity of the ovarian cancer cells to the cytotoxic effect of cDDP by regulating expression of the Cu transporter CTR1.

Predictive value of immunohistochemical expression of claudin-1 in colonic carcinoma

OBJECTIVE

Colonic carcinoma is one of the most common cancers worldwide. Recently, the possible involvement of claudin-1, one of the major tight junction proteins, in the process of tumorigenesis has been suggested. Also, claudin-1 has emerged as a potential prognostic factor in different types of tumors. The aim of this study was to detect caludin-1 expression in colonic carcinoma and to correlate its expression with clinicopathological variables in an attempt to delineate its role as a potential new prognostic marker.

MATERIAL AND METHODS

Immunohistochemical expression of claudin-1 was assessed in 50 Egyptian patients with colonic adenocarcinoma. The predictive performance of claudin-1 expression was statistically evaluated.

RESULTS

Decreased claudin-1 expression was found in 62% of colonic adenocarcinoma cases while similar expression was found in 38% of the cases. Statistical analysis showed a statistically significant inverse correlation between claudin-1 expression and tumor grade, depth of invasion, lymph node involvement, and tumor stage. Regression analysis showed that claudin-1 decreased expression significantly predicts that the tumor is of a high grade, high stage, and is associated with lymph node involvement. ROC curve analysis showed that claudin-1 had a sensitivity of 88.24% and a specificity of 81.25% for the prediction of tumor stage and a sensitivity of 73.33% and a specificity of 82.86% for the prediction of lymph node involvement.

CONCLUSIONS

Claudin-1 decreased expression in colonic carcinoma contributes to tumor dedifferentiation, invasion and metastasis. Claudin-1 expression could be used as a predictor of colonic carcinoma stage and lymph node status with a high sensitivity and specificity.

Current and emerging concepts in tumour metastasis

Disseminated cancer accounts for most deaths due to malignancy. Despite this, research has focused predominantly on tumour development and progression at the primary site. Recently, attention has shifted towards the field of tumour metastasis. Several new and exciting concepts that have emerged in the past few years may shed light on this complex area. The established canonical theory of tumour metastasis, as a process emerging from a stepwise accumulation of genetic events fuelled by clonal evolution, has been challenged. New evidence suggests that malignant cells can disseminate at a much earlier stage than previously recognized in tumourigenesis. These findings have direct relevance to clinical practice and shed new light on tumour biology. Gene-profiling studies support this theory, suggesting that metastatic ability may be an innate property shared by the bulk of cells present early in a developing tumour mass. There is a growing recognition of the importance of host factors outside the primary site in the development of metastatic disease. The role of the 'pre-metastatic niche' is being defined and with this comes a new understanding of the function of bone marrow-derived progenitor cells in directing the dissemination of malignant cells to distant sites. Current research has highlighted the crucial roles played by non-neoplastic host cells within the tumour microenvironment in regulating metastasis. These new concepts have wide-ranging implications for our overall understanding of tumour metastasis and for the development of cancer therapeutics.