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Introduction: Claudin-4 has been described as a highly sensitive immunocytochemical marker for detection of metastatic carcinoma cells in effusion cytology specimens. This study aims to challenge the performance of claudin-4 in different types of malignancies and low cellularity specimens, by comparison with other markers in a large cohort of carcinomatous effusion specimens., Methodology: Cell block preparations from peritoneal and pleural fluid specimens were retrieved, with malignant (carcinoma) diagnoses confirmed by review of hospital diagnosis code and pathology reports. Claudin-4, BerEP4, CEA, and MOC31 immunocytochemistry were performed and scored by expression proportion and intensity. Tumor cellularity was assessed for subgroup analysis of low cellularity specimens., Results: Totally 147 specimens (70 pleural, 77 peritoneal) of 68 lung, 62 breast, 9 gynecological, and 7 gastrointestinal carcinomas were retrieved. The average proportion expression of claudin-4 was highest (89.6%, vs. CEA 40.5%, BerEp4 18.6%, MOC31 16.8%) and the percentage of strong expression was highest for claudin-4 (72.1%). Expression levels of claudin-4 were consistently higher than other markers in subgroups of all primary sites. The difference was more significant for low cellularity specimens. High (≥50%) proportion expression was seen for 96.61% of cases for claudin-4 (vs. BerEp4 8.77%, CEA 46.55%, MOC31 8.77%, p < 0.001). These factors contributed to a low concordance between claudin-4 and BerEp4, CEA and MOC31 (K = 0.010-0.043)., Conclusion: Claudin-4 is more sensitive than CEA, BerEp4 and MOC31, suitable for low cellularity specimens of most types of metastatic carcinoma and is a robust immunocytochemical marker for carcinoma that can be used solitarily., (© 2024 The Author(s). Diagnostic Cytopathology published by Wiley Periodicals LLC.)

Background/aim: The potential of the DNA mismatch repair (MMR) system as a prognostic predictor has been evaluated in several cancer types. However, associations between MMR and the prognostic factors of ovarian cancer are poorly understood., Patients and Methods: MLH1 expression was evaluated by immunohistochemistry in patients with advanced serous ovarian cancer treated with platinum- and taxane-based chemotherapy. Associations between MLH1 expression and clinicopathological factors as well as claudin-4 expression were examined., Results: Low MLH1 expression was significantly associated with increased progression-free and overall survival, and a normalisation of CA125 levels after chemotherapy. Additionally, low claudin-4 expression was more frequently found among the group with low MLH1 expression., Conclusion: Low MLH1 expression was associated with improved prognosis and is a possible predictor of the chemosensitivity of ovarian cancer. Claudin-4 might be involved in the molecular mechanisms underlying how MLH1 influences survival and chemosensitivity in patients with ovarian cancer., (Copyright© 2019, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

The tight junction protein claudin-4 has been reported to be overexpressed in advanced ovarian cancer. We investigated the prognostic significance of claudin-4 overexpression and whether claudin-4 expression could predict platinum response in primary ovarian carcinoma (OC). Claudin-4 expression was evaluated by immunohistochemistry in a tissue microarray of 140 OCs. Multivariable Cox-regression models were used to assess the effect of claudin-4 overexpression on progression-free survival and overall survival (OS). Kaplan-Meier survival analyses and the logrank test were performed comparing claudin-4 high and low groups. The association between claudin-4 expression and platinum resistance was assessed using risk ratios and the Pearson χ test. A dataset of >1500 epithelial ovarian cancers was used to study the association between CLDN4 mRNA and survival. Of 140 evaluable cases, 71 (51%) displayed high claudin-4 expression. Claudin-4 overexpression predicted shorter 5-yr progression-free survival and OS in univariable analyses [hazard ratio (HR)=1.6 (1.1-2.5), P=0.020 and HR=1.6 (1.0-2.4), P=0.041, respectively]. Hazard of relapse was similar [HR=1.5 (1.0-2.4)] after adjustment for age, stage, type, and BRCA1/2 status in a multivariable analysis, but the evidence was slightly weaker (P=0.076). Validation in an external cohort confirmed the association between high expression of CLDN4 and poor 10-yr OS [HR=1.3 (1.1-1.5), P<0.001]. However, no confident association between claudin-4 and platinum sensitivity was found in our cohort [risk ratio=1.2 (0.7-2.0), P=0.3]. These findings suggest that high expression of claudin-4 may have a prognostic value in OC. The role of claudin-4 in the development of platinum resistance remains unclear.

Objective: To investigate the clinicopathologic and prognostic features of Claudin-low breast cancers (CLBC). Methods: Tissue microarray sections were scored semiquantitatively for the immunohistochemical expression of claudin-1, -3, -4, -7 and -8 in 233 cases of invasive breast cancers collected from Qingdao Central Hospital from January 2010 to December 2011. Results: The expression rate of Claudin-3 (72/212, 33.9%) and -4 (56/212, 45.2%) was most similar, and Claudin-4 showed the highest expression. Twenty one cases (21/212, 9.0%) were diagnosed as CLBC, with triple-negative breast cancer (TNBC) accounted for the highest proportion (11/21, 52.4%). Among the CLBC cases, the invasive carcinoma no special type (66.7%, 14/21) and metaplastic carcinoma (14.3%, 3/21) were mostly seen, while metaplastic squamous carcinoma did not show Claudin-low pattern. Compared to the non CLBC in this cohort, CLBC had higher proportion of histologic grade 3 and tumors larger than 2 cm, and the proportions were slightly lower than TNBC. Patients with CLBC had lower 5 year disease-free( P >0.05) and overall survival rates( P =0.018). Conclusion: CLBC shows distinct clinicopathologic and prognostic features comparing to other subtypes, and is associated with poor prognosis.

Claudins constitute a group of principal proteins forming the tight junctional complex. The altered expression of selected claudins has been reported in several human cancers. The purpose of this study was to investigate the expression of claudin-1 and claudin-4 in oral squamous cell carcinoma (OSCC) and examine its relationship with patient clinical-pathologic features. Forty-five OSCC cases were enrolled. Patient clinical, pathologic and follow-up data were reviewed and the claudin-1 and claudin-4 expression was analyzed immunohistochemically. Positive claudin-1 and claudin-4 immunoreactivities were noted in 86.7 and 80 % of cases, respectively. The majority of cases showed the staining in less than 25 % of cancer cells. The increased claudin-1 expression was significantly associated with the high pathologic grade, the presence of microscopic perineural invasion, vascular invasion, nodal metastasis, and advanced clinical stage. No relationship between various clinico-pathologic parameters and differential claudin-4 expression was observed. Claudin-1 may play a role in OSCC progression and could serve as a prognostic marker of advanced disease.

The high recurrence rate after surgery is the main reason for the poor prognosis of esophageal squamous cell carcinoma (ESCC) patients. Finding indicators of recurrence and taking adjuvant therapy may be useful for patients in high risk of recurrence. claudin-4 (CLDN4) is the core protein to form the tight junction, which plays an important role in cell adhesion, and its aberrant expression were detected in various cancers while its expression and functions in ESCC still remained unclear. Here, we detected the expression of CLDN4 in 114 ESCC tissue samples by real-time RT-PCR and immunohistochemistry, and the result showed that the low expression of CLDN4 correlated with a higher T staging (P = 0.010), lymphatic metastasis (P < 0.001) and recurrence status (P = 0.002). And the Cox regression analysis showed that the T classification (P = 0.005), lymph node metastasis (P = 0.003) and low CLDN4 expression (P = 0.029) were independent risk factors of recurrence. Further, we proved the CLDN4 in inhibiting growth, colony formation and invasion in vitro by establishing two stable CLDN4-silencing ESCC cell lines. In conclusion, CLDN4 played an important role in preventing metastasis and could be an effective biomarker to predict the recurrence of ESCC.

Introduction: To investigate the immunohistochemical expression of claudin-1, claudin-3, and claudin-4 in triple-negative breast carcinomas and compare it with several clinicopathologic parameters as well as their expression in luminal cancers., Materials and Methods: A total of 128 cases of breast carcinoma were included in the study. For all these cases, immunohistochemistry for estrogen and progesterone receptors, Ki-67, and Her2 had already been performed, whereas Her2 2+ cases had been further characterized as positive or negative for Her2 amplification with the chromogenic in situ hybridization technique. Seventy-six tumors were triple negative. The remaining 52 were luminal cancers. All tumors were evaluated for the expression of claudin-1, claudin-3, and claudin-4., Results: In the triple-negative group, the positive expression of claudin-3 and claudin-4 was related to unfavorable and favorable prognostic factors, respectively. Claudin-1 was not related to any parameter under evaluation. In the luminal cancer group, claudin-4 positivity was related to a shorter disease-free survival, whereas the inverse was observed for claudin-3. Moreover, all 3 claudins increased with increase of the grade and Ki-67 value in the luminal cancers., Conclusion: A distinct prognostic significance in the expression of claudin-3 and mostly of claudin-4 between triple-negative and luminal breast carcinomas was identified. Specifically, in triple-negative carcinomas, claudin-4 positivity could probably be considered as a biomarker of favorable prognosis, whereas in luminal cancers with claudin-4-positive expression, the administration of targeted therapy should eventually be part of the patients' management in the near future.

Background: Aberrant expression of claudin proteins has been reported in a variety of cancers. Previous studies have demonstrated that overexpression of claudin may promote tumorigenesis and metastasis through increased invasion and survival of tumor cells. However, the prognostic significance of claudin-4 in gastric cancer remains unclear., Methods: Immunohistochemistry was used to analyze the expression of claudin-4 in 329 clinical gastric cancer specimens and 44 normal stomach samples, 21 intestinal metaplasia samples, and 21 adjacent precursor lesions dysplasia samples. Statistical analysis methods were used to evaluate the relationship between claudin-4 expression and various clinicopathological parameters. Univariate and multivariate analyses were performed, respectively, to detect the independent predictors of survival., Results: Claudin-4 expression was present in only 7(15.9%) normal gastric samples, but expression of claudin-4 in the intestinal metaplasia lesions and dysplasia lesions was 90.5% and 95.2%, respectively. The expression of claudin-4 was significantly associated with histological differentiation (P < 0.001) and tumor growth patterns (P < 0.001) but not associated with patient survival. However, intermediate type staining of claudin-4 exhibited a trend of correlation with patients' survival (P = 0.023). The five-year survival rate with low expression of claudin-4 in intermediate type (76.4%) was similar to expanding type (64.5%), while the high expression group (46.6%) was closer to infiltrative type (50.7%)., Conclusions: The findings in this study demonstrate claudin-4 aberrant expression in gastric cancer and precursor lesions. The expression of claudin-4 could serve as a basis for identifying gastric cancer of the intermediate type.

Objectives: Novel imaging methods based on specific molecular targets to detect both established neoplasms and their precursor lesions are highly desirable in cancer medicine. Previously, we identified claudin-4, an integral constituent of tight junctions, as highly expressed in various gastrointestinal tumours including pancreatic cancer. Here, we investigate the potential of targeting claudin-4 with a naturally occurring ligand to visualise pancreatic cancer and its precursor lesions in vitro and in vivo by near-infrared imaging approaches., Design: A non-toxic C-terminal fragment of the claudin-4 ligand Clostridium perfringens enterotoxin (C-CPE) was labelled with a cyanine dye (Cy5.5). Binding of the optical tracer was analysed on claudin-4 positive and negative cells in vitro, and tumour xenografts in vivo. In addition, two genetically engineered mouse models for pancreatic intraepithelial neoplasia (PanIN) and pancreatic cancer were used for in vivo validation. Optical imaging studies were conducted using 2D planar fluorescence reflectance imaging (FRI) technology and 3D fluorescence-mediated tomography (FMT)., Results: In vitro, the peptide-dye conjugate showed high binding affinity to claudin-4 positive CAPAN1 cells, while claudin-4 negative HT1080 cells revealed little or no fluorescence. In vivo, claudin-4 positive tumour xenografts, endogenous pancreatic tumours, hepatic metastases, as well as preinvasive PanIN lesions, were visualised by FRI and FMT up to 48 h after injection showing a significantly higher average of fluorochrome concentration as compared with claudin-4 negative xenografts and normal pancreatic tissue., Conclusions: C-CPE-Cy5.5 combined with novel optical imaging methods enables non-invasive visualisation of claudin-4 positive murine pancreatic tumours and their precursor lesions, representing a promising modality for early diagnostic imaging.

Different expression of claudins and E-cadherin has been described in the pathogenesis and progression of breast cancer. Changes in the expression of these junctional molecules have also been described as being of prominent importance in other cancers as well. Thus, we aimed at exploring the potential prognostic relevance of these cell junctional molecules in breast carcinoma cases. Expression of claudin-1, -3, -4, -5, -7, -8, -10, -15, -18 and E-cadherin at mRNA level was evaluated in correlation with survival in publicly available datasets containing expression measurements of 1809 breast cancer patients. Breast cancer tissues of 636 patients were evaluated with tissue microarray technique and immunohistochemical method for claudin-1, -2, -3, -4, -5, -7 and E-cadherin protein expression. In 96 cases lymph node metastases were also subjects of the study. Claudin expression bears prognostic information in itself. Based on bioinformatic data analysis, the meta-gene of claudin-3, -4, -7 and E-cadherin has proved the most powerful in predicting survival. An immunohistochemical protein profile consisting of claudin-2, -4 and E-cadherin was able to predict outcome in the most effective manner in the training set. Combining the overlapping members of the distinct methods resulted in the CC index (consisting of claudin-4 and E-cadherin, a.k.a. CURIO), which was able to accurately predict relapse-free survival in the validation cohort (p=0.029) in a more efficient way than its components. Cox regression analysis including clinicopathological variables and the average CC score showed that in univariate analysis most of them were prognostic but most of them lost independent prognostic value in multivariate analysis except for the CC index, the subtypes defined by immunoprofiling and vascular invasion. On the other hand, the CC index was able to further refine prognosis splitting good vs. poor prognosis patients into two clusters in these subgroups. Evaluation of lymph node metastases has shown that decreased expression of claudin-1 and elevated expression of claudin-4 can predict worse prognosis in breast cancers spreading to the regional lymph nodes. The defined claudin-cadherin index provides additional prognostic information besides the routinely utilized diagnostic approaches and factors. The level of expression of certain claudins can be of prognostic significance in regional lymph node metastases.

Background: Identification of prognostic markers would be useful in the clinical management of patients with pancreatic ductal adenocarcinoma (PDAC). The clinical relevance of claudin-4 (CLDN4), recently identified as overexpressed in PDAC, is unknown., Methods: Using quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR), we analyzed CLDN4 mRNA expression in a panel of 9 pancreatic cancer cell lines and formalin-fixed paraffin-embedded (FFPE) tissues from 100 patients with PDAC. The CLDN4 expression levels were then correlated with clinicopathological variables and patient outcome. We also performed immunohistochemical analysis in 20 FFPE samples of PDAC to investigate the expression of CLDN4 protein., Results: Increased expression of CLDN4 was confirmed in all the pancreatic cancer cell lines tested compared with normal ductal epithelial cells and fibroblasts. We found that low expression of CLDN4 was significantly associated with shorter survival in patients with PDAC (hazard ratio; 1.362, 95% confidence interval; 1.011-1.873, P = 0.0419). Patients with high CLDN4 expression survived longer for a median of 63.0 months, compared with 14.7 months in patients with low CLDN4 expression (P = 0.0067). In immunohistochemical analysis, the level of CLDN4 mRNA expression was significantly correlated with the expression of CLDN4 protein (P = 0.0168)., Conclusion: Increased expression of CLDN4 mRNA predicts better prognosis in PDAC.

Claudin 4 is a cellular adhesion molecule that is frequently overexpressed in ovarian cancer and other epithelial cancers. In this study, we sought to determine whether the expression of claudin 4 is associated with outcome in ovarian cancer patients and may be involved in tumor progression. We examined claudin 4 expression in ovarian cancer tissues and cell lines, as well as by immunohistochemical staining of tissue microarrays (TMAs; n = 500), spheroids present in patients' ascites, and spheroids formed in vitro. Claudin 4 was expressed in nearly 70% of the ovarian cancer tissues examined and was differentially expressed across ovarian cancer subtypes, with the lowest expression in clear cell subtype. No association was found between claudin 4 expression and disease-specific survival in any subtype. Claudin 4 expression was also observed in multicellular spheroids obtained from patients' ascites. Using an in vitro spheroid formation assay, we found that NIH:OVCAR5 cells treated with shRNA against claudin 4 required a longer time to form compact spheroids compared to control NIH:OVCAR5 cells that expressed high levels of claudin 4. The inability of the NIH:OVCAR5 cells treated with claudin 4 shRNA to form compact spheroids was verified by FITC-dextran exclusion. These results demonstrate a role for claudin 4 and tight junctions in spheroid formation and integrity.