Claudin expression in pulmonary adenoid cystic carcinoma and mucoepidermoid carcinoma.

Background: Although the expression of tight junction protein claudins (CLDNs) is well known in common histological subtypes of lung cancer, it has not been investigated in rare lung cancers. The aim of our study was to examine the expression of different CLDNs in pulmonary salivary gland tumors. Methods: 35 rare lung cancers including pathologically confirmed 12 adenoid cystic carcinomas (ACCs) and 23 mucoepidermoid carcinomas (MECs) were collected retrospectively. Immunohistochemical (IHC) staining was performed on formalin fixed paraffin embedded (FFPE) tumor tissues, and CLDN1, -2, -3, -4, -5, -7, and -18 protein expressions were analyzed. The levels of immunopositivity were determined with H-score. Certain pathological characteristics of ACC and MEC samples (tumor grade, presence of necrosis, presence of blood vessel infiltration, and degree of lymphoid infiltration) were also analyzed. Results: CLDN overexpression was observed in both tumor types, especially in CLDN2, -7, and -18 IHC. Markedly different patterns of CLDN expression were found for ACC and MEC tumors, especially for CLDN1, -2, -4, and -7, although none of these trends remained significant after correction for multiple testing. Positive correlations between expressions of CLDN2 and -5, CLDN3 and -4, and CLDN5 and -18 were also demonstrated. Tumors of never-smokers presented lower levels of CLDN18 than tumors of current smokers (p-value: 0.003). Conclusion: This is the first study to comprehensively describe the expression of different CLDNs in lung ACC and MEC. Overexpression of certain CLDNs may pave the way for targeted anti-claudin therapy in these rare histological subtypes of lung cancer.

Dysregulated claudin expression significantly effect breast cancer disease progression.

Background: In this study, the role of claudins in cancer progression was explored among breast cancer-affected women. Methodology: Two cohorts (discovery and validated) of breast cancer-affected women were used. In discovery cohort, 90 freshly excised breast tumor tissues along with adjacent cancer free specimens were collected at the time of surgery. These specimens were processed for RNA isolation and complementary DNA synthesis. After designing primers for claudin 3, claudin 4, and claudin 7, these sequences were synthesized from Macrogen, Korea. Claudin expression in respective tumors and controls was assessed using quantitative reverse transcription polymerase chain reaction. Any probable correlation of these molecules with various clinicopathological parameters was explored. For validation, a publicly available dataset of 2088 breast cancer patients was accessed. Claudin expression of these patients was analyzed for given clinical parameters and compared with earlier findings of discovery cohort. Results: Discovery cohort comprised 17% luminal A, 63% luminal B, 8% human epidermal growth factor receptor 2 enrich, and 12% triple-negative breast cancer tumor. High claudin 3 expression was significantly correlated with tumor size >2 cm and menopausal status. Claudin 7 expression was upregulated among poorly differentiated tumor patients. Both claudins 3/4 showed significant correlation with tumor grade, stage, size, and metastasis. Claudin-low subtype was also found in 18% of the cohort. Conclusion: Claudins impart a significant role in cell differentiation and disease progression. Hence, claudin cluster can be ascertained as the disease biomarkers for breast cancer.

The prognostic impact of Claudin 6 in papillary renal cell carcinoma.

BACKGROUND: Claudins are promising biomarkers for diagnosis and prognosis or targets for treatment. They play a major role in signal transduction and are important in nearly all aspects of tumorigenesis. Claudin 6 is a member of the claudin family and is part of the tight junction molecule. It is reactivated in several cancer types and serves as prognostic marker in, for example, gastric, breast or non small cell lung cancer. The prognostic role of Claudin 6 in renal cell carcinoma (RCC), especially in papillary RCC (pRCC), is still unclear. PATIENTS AND METHODS: The patients' sample collection was a joint collaboration of the PANZAR consortium. Patients' medical history and tumor specimens were collected from n = 240 and n = 128 patients with type 1 and 2 pRCC, respectively. Expression of Claudin 6 was determined by immunohistochemistry. RESULTS: In total, Claudin 6 staining was positive in 55 of 240 type 1 and 30 of 128 type 2 pRCC cases. Kaplan-Meier analysis disclosed an overall survival of 84% for Claudin 6- compared to 78% for Claudin 6 + in pRCC type 1 tumors (p = 0.449, log-rank) and 68% for Claudin 6- compared to 65.4% for Claudin 6 + in pRCC type 2 tumors (p = 0.364, log-rank). CONCLUSION: In this study, claudin 6 expression showed no significant association regarding overall survival (OS) and therefore did not qualify as a prognostic marker in pRCC. Future studies will have to determine, whether Claudin 6 plays a prognostic role in other RCC entities. In addition, the function of Claudin 6 as a predictive marker for therapeutic approaches has to be evaluated in future studies.

Proteomic identification of tumor- and metastasis-associated galectin-1 in claudin-low breast cancer.

BACKGROUND: Metastasis and mortality remain high among breast cancer patients with the claudin-low subtype because these tumors are aggressive, chemoresistant, and lack targeted therapies. Our objective was to utilize discovery-based proteomics to identify proteins associated with claudin-low primary and metastatic tumors to gain insight into pathways and mechanisms of tumor progression. METHODS: We used nano-LC-MS/MS proteomics to analyze orthotopic and metastatic tumors from the syngeneic murine T11 tumor model, which displays gene expression profiles mirroring human claudin-low tumors. Galectin-1 identity, expression and spatial distribution were investigated by biochemical and immunochemical methods and MALDI/IMS. RNA seq data from mouse and human tumors in our study and publicly available microarray data were analyzed for differential galectin-1 expression across breast cancer subtypes. RESULTS: Galectin-1, an N-acetyllactosamine-binding protein, exhibited the highest sequence coverage and high abundance rank order among nano-LC-MS/MS-identified proteins shared by T11 claudin-low tumors but not normal tissue. Label-free quantitation, Western immunoblot and ELISA confirmed galectin-1 identity and significant differential expression. MALDI/IMS spatial mapping and immunohistochemistry detected galectin-1 in T11 metastatic lung foci. Immunohistochemistry of human claudin-low tumors demonstrated intermediate-to-high intensity galectin-1 staining of tumor and stroma. Gene expression analysis of mouse and human tumors found the highest galectin-1 levels in the claudin-low breast cancer subtype. CONCLUSIONS: Proteomics and genomics reveal high expression of galectin-1 protein and RNA in primary and metastatic claudin-low breast cancer. GENERAL SIGNIFICANCE: This work endorses proteomic approaches in cancer research and supports further investigations of the function and significance of galectin-1 overexpression in claudin-low tumor progression.

Sandwich-Type Electrochemical Paper-Based Immunosensor for Claudin 7 and CD81 Dual Determination on Extracellular Vesicles from Breast Cancer Patients.

This study is focused on identifying novel epithelial markers in circulating extracellular vesicles (EVs) through the development of a dual sandwich-type electrochemical paper-based immunosensor for Claudin 7 and CD81 determination, as well as its validation in breast cancer (BC) patients. This immunosensor allows for rapid, sensitive, and label-free detection of these two relevant BC biomarkers. Under optimum conditions, the limit of detection for Claudin 7 was 0.4 pg mL-1, with a wide linear range of 2 to 1000 pg mL-1, while for CD81, the limit of detection was 3 pg mL-1, with a wide linear range of 0.01 to 10 ng mL-1. Finally, we validated Claudin 7 and CD81 determination in EVs from 60 BC patients and 20 healthy volunteers, reporting higher diagnostic accuracy than the one observed with classical diagnostic markers. This analysis provides a low-cost, specific, versatile, and user-friendly strategy as a robust and reliable tool for early BC diagnosis.

Claudin-18 as a Marker for Identifying the Stomach and Pancreatobiliary Tract as the Primary Sites of Metastatic Adenocarcinoma.

Identification of the primary site of cancer is essential for the treatment of patients with cancer. Numerous immunohistochemical markers have been developed to determine the differentiation of tumor cells and suggest possible primary sites, but markers of gastric and pancreatic adenocarcinomas are still lacking. Claudin-18 is a tight-junction protein uniquely expressed in gastric epithelial cells and has been shown to be expressed in gastric and pancreatic adenocarcinoma. Whether claudin-18 can be used as a marker for identifying the primary site of cancer is still unclear. In this study, we used the immunohistochemical method to stain claudin-18 in tissue arrays containing 575 carcinomas from different anatomic sites and representative sections of 157 metastatic adenocarcinomas. In the group of primary tumors, claudin-18 was frequently expressed in gastric, pancreatic, and pulmonary mucinous adenocarcinomas. Half of cholangiocarcinomas and ovarian mucinous carcinomas and some colorectal and pulmonary adenocarcinomas were also positive for claudin-18. In the metastatic cohort, 15 of 17 (88%) gastric adenocarcinomas, 18 of 23 (78%) pancreatic adenocarcinomas, and 4 of 7 (57%) cholangiocarcinomas and gallbladder adenocarcinomas were positive for claudin-18. Only 4 tumors that originated outside the stomach and pancreatobiliary tract were positive for claudin-18. After normalization to the tumor frequency, the sensitivity of claudin-18 for identifying the stomach and pancreatobiliary tract as primary tumor sites was 79%, and the specificity was 93%. The positive and negative predictive values were 76% and 94%, respectively. In conclusion, claudin-18 represents a sensitive and specific marker for stomach and pancreatobiliary adenocarcinoma that may be a useful diagnostic tool in routine surgical pathology.

Circulating Ouabain Modulates Expression of Claudins in Rat Intestine and Cerebral Blood Vessels.

The ability of exogenous low ouabain concentrations to affect claudin expression and therefore epithelial barrier properties was demonstrated previously in cultured cell studies. We hypothesized that chronic elevation of circulating ouabain in vivo can affect the expression of claudins and tight junction permeability in different tissues. We tested this hypothesis in rats intraperitoneally injected with ouabain (1 µg/kg) for 4 days. Rat jejunum, colon and brain frontal lobes, which are variable in the expressed claudins and tight junction permeability, were examined. Moreover, the porcine jejunum cell line IPEC-J2 was studied. In IPEC-J2-cells, ouabain (10 nM, 19 days of incubation) stimulated epithelial barrier formation, increased transepithelial resistance and the level of cSrc-kinase activation by phosphorylation, accompanied with an increased expression of claudin-1, -5 and down-regulation of claudin-12; the expression of claudin-3, -4, -8 and tricellulin was not changed. In the jejunum, chronic ouabain increased the expression of claudin-1, -3 and -5 without an effect on claudin-2 and -4 expression. In the colon, only down-regulation of claudin-3 was observed. Chronic ouabain protected the intestine transepithelial resistance against functional injury induced by lipopolysaccharide treatment or by modeled acute microgravity; this regulation was most pronounced in the jejunum. Claudin-1 was also up-regulated in cerebral blood vessels. This was associated with reduction of claudin-3 expression while the expression of claudin-5 and occludin was not affected. Altogether, our results confirm that circulating ouabain can functionally and tissue-specifically affect barrier properties of epithelial and endothelial tissues via Na,K-ATPase-mediated modulation of claudins expression.

Heme induces rapid endothelial barrier dysfunction via the MKK3/p38MAPK axis.

Several studies demonstrate that hemolysis and free heme in circulation cause endothelial barrier dysfunction and are associated with severe pathological conditions such as acute respiratory distress syndrome, acute chest syndrome, and sepsis. However, the precise molecular mechanisms involved in the pathology of heme-induced barrier disruption remain to be elucidated. In this study, we investigated the role of free heme in the endothelial barrier integrity and mechanisms of heme-mediated intracellular signaling of human lung microvascular endothelial cells (HLMVECs). Heme, in a dose-dependent manner, induced a rapid drop in the endothelial barrier integrity of HLMVECs. An investigation into barrier proteins revealed that heme primarily affected the tight junction proteins zona occludens-1, claudin-1, and claudin-5, which were significantly reduced after heme exposure. The p38MAPK/HSP27 pathway, involved in the regulation of endothelial cytoskeleton remodeling, was also significantly altered after heme treatment, both in HLMVECs and mice. By using a knockout (KO) mouse for MKK3, a key regulator of the p38MAPK pathway, we showed that this KO effectively decreased heme-induced endothelial barrier dysfunction. Taken together, our results indicate that targeting the p38MAPK pathway may represent a crucial treatment strategy in alleviating hemolytic diseases.

Differential regulation of claudin-2 and claudin-15 expression in children and adults with malabsorptive disease.

Intestinal Na+-nutrient cotransport depends on claudin-2 and claudin-15 mediated Na+ recycling. Expression of these proteins is coordinately regulated during postnatal development. While expression of claudin-2 and claudin-15 has been studied in inflammatory bowel disease (IBD) and celiac disease (CD), it has not been assessed in other malabsorptive diseases, and no reports have compared expression in children and adults. We used quantitative immunofluorescence microscopy to assess claudin-2 and claudin-15 expression in duodenal biopsies from children and adults with malabsorptive disease and healthy controls. Consistent with previous work in rodents, claudin-2 expression in healthy children was markedly greater, and claudin-15 expression was less, than that in adults. Claudin-2 expression was increased in adults with CD and downregulated in children with graft-versus-host disease (GVHD). In contrast, claudin-15 expression was reduced in adults with GVHD and common variable immunodeficiency (CVID). These data show that one of the two Na+/water pore-forming claudins is upregulated in CD and downregulated in GVHD and CVID. The specific claudin whose expression changes, however, reflects the age of the patient (child or adult). We conclude that contributions of claudin-2 and claudin-15 to pathophysiology of and responses to diarrhea in children and adults with GVHD and CVID differ from those in CD and IBD.

The Significance of Relative Claudin Expression in Odontogenic Tumors.

Claudins are integral to the structure and function of tight junctions. Altered claudin expression has been shown to affect disease behavior and patient prognosis in various neoplasms. The objectives of this study were to analyze the claudin-1, -4 and -7 expression in odontogenic tumors and characterize their expression pattern in distinct tumor cell types in relation to the recurrence potential. Sixty-nine cases of odontogenic tumors, including 43 ameloblastomas (AM), 17 adenomatoid odontogenic tumors (AOT), 6 ameloblastic fibromas (AF) and 3 ameloblastic carcinomas (AC) were investigated for claudin-1, -4 and -7 expression immunohistochemically. The staining was analyzed semi-quantitatively and categorized into 4 levels, based on the percentage of positively stained neoplastic epithelial cells. Claudin-1 was expressed in all AOT and AF cases, whereas most AC (66.7%) showed no expression. The claudin-1 staining was moderate-to-intense in the odontogenic epithelium of AF. In contrast, its staining of ameloblast-like cells and stellate reticulum-like cells in AM was weak. Claudin-7 expression was noted in all tumor types studied, while the expression of claudin-4 was limited and mainly localized in the squamous differentiated cells of AM and AC. AM showed significantly higher claudin-4, but lower claudin-7 expression than AOT. In addition, AC showed diminished claudin-1 immunoreactivity, compared to AOT. Low claudin-1 expression in AM was significantly associated with the increased clinical recurrence. The loss of claudin-1 may underlie the locally invasive nature of AM.

Role of Claudin Proteins in Regulating Cancer Stem Cells and Chemoresistance-Potential Implication in Disease Prognosis and Therapy.

Claudins are cell-cell adhesion proteins, which are expressed in tight junctions (TJs), the most common apical cell-cell adhesion. Claudin proteins help to regulate defense and barrier functions, as well as differentiation and polarity in epithelial and endothelial cells. A series of studies have now reported dysregulation of claudin proteins in cancers. However, the precise mechanisms are still not well understood. Nonetheless, studies have clearly demonstrated a causal role of multiple claudins in the regulation of epithelial to mesenchymal transition (EMT), a key feature in the acquisition of a cancer stem cell phenotype in cancer cells. In addition, claudin proteins are known to modulate therapy resistance in cancer cells, a feature associated with cancer stem cells. In this review, we have focused primarily on highlighting the causal link between claudins, cancer stem cells, and therapy resistance. We have also contemplated the significance of claudins as novel targets in improving the efficacy of cancer therapy. Overall, this review provides a much-needed understanding of the emerging role of claudin proteins in cancer malignancy and therapeutic management.

Combined Immunohistochemistry for the "Three 7" Markers (CK7, CD117, and Claudin-7) Is Useful in the Diagnosis of Chromophobe Renal Cell Carcinoma and for the Exclusion of Mimics: Diagnostic Experience from a Single Institution.

BACKGROUND: There is a morphological overlap among renal epithelial tumors, particularly chromophobe renal cell carcinoma (CHRCC), clear cell renal cell carcinoma (CCRCC), renal oncocytoma (RO), and papillary renal cell carcinoma (PRCC). Discriminating between these tumors is important but sometimes challenging. This study is aimed at evaluating the clinical usefulness of the combined immunochemistry for the "three 7" markers (CK7, CD117, and Claudin-7) to distinguish chromophobe renal cell carcinoma from these mimics. METHODS: Immunochemical staining for CK7, CD117, and Claudin-7 was performed in 68 CHRCCs, 199 CCRCCs, 32 ROs, and 30 PRCCs. Fluorescence in situ hybridization (FISH) was performed in some cases to exclude CCRCC and PRCC. The sensitivity (SE) and specificity (SP) for CHRCC as well as the immunoreactivity of each marker and their combinations were statistically evaluated. RESULTS: High positive rates for CK7 (94%), CD117 (87%), Claudin-7 (94%), and their combinations (CK7+CD117, 79%; CK7+Claudin-7, 88%; CD117+Claudin-7, 82%; CK7+CD117+Claudin-7, 76%) were observed in CHRCC compared to those in CCRCC, RO, and PRCC, with increasingly higher SP when combinations of the "three 7" markers were applied (CK7, 0.80; CD117, 0.82; Claudin-7, 0.78; CK7+CD117, 0.95; CK7+Claudin-7, 0.97; CD117+Claudin-7, 0.97; CK7+CD117+Claudin-7, 1). CONCLUSION: CK7, CD117, and Claudin-7 are frequently expressed in CHRCC with high specificity. We recommend the routine use of these 3 markers as a routine panel when making a differential diagnosis of CHRCC and excluding other mimics.

In-Depth Bioinformatic Study of the CLDN16 Gene and Protein: Prediction of Subcellular Localization to Mitochondria.

Background and Objectives: The defects in the CLDN16 gene are a cause of primary hypomagnesemia (FHHNC), which is characterized by massive renal magnesium wasting, resulting in nephrocalcinosis and renal failure. The mutations occur throughout the gene's coding region and can impact on intracellular trafficking of the protein or its paracellular pore forming function. To gain more understanding about the mechanisms by which CLDN16 mutations can induce FHHNC, we performed an in-depth computational analysis of the CLDN16 gene and protein, focusing specifically on the prediction of the latter's subcellular localization. Materials and Methods: The complete nucleotide or amino acid sequence of CLDN16 in FASTA format was entered and processed in 14 databases. Results: One CpG island was identified. Twenty five promoters/enhancers were predicted. The CLDN16 interactome was found to consist of 20 genes, mainly involved in kidney diseases. No signal peptide cleavage site was identified. A probability of export to mitochondria equal to 0.9740 and a cleavable mitochondrial localization signal in the N terminal of the CLDN16 protein were predicted. The secondary structure prediction was visualized. Νo phosphorylation sites were identified within the CLDN16 protein region by applying DISPHOS to the functional class of transport. The KnotProt database did not predict any knot or slipknot in the protein structure of CLDN16. Seven putative miRNA binding sites within the 3'-UTR region of CLDN16 were identified. Conclusions: This is the first study to identify mitochondria as a probable cytoplasmic compartment for CLDN16 localization, thus providing new insights into the protein's intracellular transport. The results relative to the CLDN16 interactome underline its role in renal pathophysiology and highlight the functional dependence of CLDNs-10, 14, 16, 19. The predictions pertaining to the miRNAs, promoters/enhancers and CpG islands of the CLDN16 gene indicate a strict regulation of its expression both transcriptionally and post-transcriptionally.

Claudin-18 expression in oesophagogastric adenocarcinomas: a tissue microarray study of 523 molecularly profiled cases.

BACKGROUND: Claudin-18 (CLDN18) is a highly specific tight junction protein of the gastric mucosa. An isoform of CLDN18, the Claudin 18.2, has recently emerged as an innovative drug target for metastatic gastric cancer. METHODS: We investigated the immunohistochemical profile of CLDN18, p53, p16, E-cadherin, MSH2, MSH6, MLH1, PSM2, HER2, and PDL-1 in a large series of 523 primary gastric carcinomas (GCs; n = 408) and gastro-oesophageal carcinomas (GECs; n = 115) and 135 matched and synchronous nodal metastases. The status of HER2 and EBER by means of chromogenic in situ hybridisation (CISH) was also evaluated. RESULTS: High membranous CLDN18 expression was present in 150/510 (29.4%) primary cases and in 45/132 (34.1%) metastases. An abnormal expression (i.e. nuclear and/or cytoplasmic) was observed in 115 (22.5%) primary cases and in 33 (25.0%) metastases. A 38.8% of the cases showed significant CLDN18 intratumoural variability among the different tissue microarray cores obtained from the same tumour. Positive membrane CLDN18 expression was statistically associated with non-antral GCs (p = 0.016), Lauren diffuse type (p = 0.009), and with EBV-associated cancers (p < 0.001). CONCLUSIONS: CLDN18 is frequently expressed in gastric and gastro-oesophageal cancers; further studies should investigate the prognostic significance of CLDN18 heterogeneity in order to implement its test into clinical practice.

Claudins, VEGF, Nrf2, Keap1, and Nonspecific Airway Hyper-Reactivity Are Increased in Mice Co-Exposed to Allergen and Acrolein.

Acrolein, an α/ß-unsaturated aldehyde, is volatile at room temperature. It is a respiratory irritant found in environmental tobacco smoke, which can be generated during cooking or endogenously at sites of injury. An acute high concentration of uncontrolled irritant exposure can lead to an asthma-like syndrome known as reactive airways dysfunction syndrome (RADS). However, whether acrolein can induce RADS remains poorly understood. The aim of study is to develop a RADS model of acrolein inhalation in mice and to clarify the mechanism of RADS. Mice were treated with ovalbumin (OVA) and exposed to acrolein (5 ppm/10 min). Airway hyper-responsiveness (AHR) was measured on days 24 and 56, and samples were collected on days 25 and 57. Tight junction protein, antioxidant-associated protein, and vascular endothelial growth factor (VEGF) levels were estimated by Western blotting and immunohistochemical staining. Reactive oxygen species (ROS) was calculated using enzyme linked immunosorbent assays. Acrolein or OVA groups exhibited an increase in airway inflammatory cells and AHR compared to a sham group. These effects were further increased in mice in the OVA + acrolein exposure group than in the OVA exposure group and persisted in the acrolein exposure group for 8 weeks. CLDNs, carbonyls, VEGF, Nrf2, and Keap1 were observed in the lungs. Our data demonstrate that acrolein induces RADS and that ROS, angiogenesis, and tight junction proteins are involved in RADS in a mouse model.

Immunoreactivity patterns of tight junction proteins are useful for differential diagnosis of human salivary gland tumors.

The expression pattern of tight junction proteins (TJPs) varies among organs and tumor types. In this study, we examined the immunoreactivity of claudin (CLDN)-1, -4, and -7, and JAM-A in salivary gland tumors (SGTs) by histological types and cell types to estimate their usefulness as differential diagnostic markers. Immunoreactivity of CLDN1 was higher in ductal epithelium cells of SGTs than in non-tumor tissues. Conversely, immunoreactivity of CLDN1 was significantly decreased in basal/myoepithelium cells of SGTs compared with that in non-tumor tissues. There was no significant difference between the immunoreactivity of CLDN1 in benign tumors and that in malignant tumors. Immunoreactivity of CLDN4, CLDN7, and JAM-A in ductal epithelium cells was higher in many SGTs than in non-tumor tissues. There was a difference depending on the histological type of SGT in immunoreactivity of CLDN4, CLDN7, and JAM-A in basaloid/myoepithelial cells. It was possible to classify SGTs by a hierarchical clustering using immunoreactivity of TJPs. The results suggest that an immunohistochemical marker panel including these TJPs may be useful for differential diagnosis of SGTs and that CLDN1 is associated with tumorigenesis of SGTs.

High-level cytoplasmic claudin 3 expression is an independent predictor of poor survival in triple-negative breast cancer.

BACKGROUND: The subtype of claudin-low breast cancer can be reliably determined only by gene-expression profiling. Attempts have been made to develop immunohistochemical surrogates, which nearly always focus on membranous claudin expression. METHODS: We assessed the immunohistochemical expression of both membranous and cytoplasmic claudins 3, 4 and 7 in a series of 197 non-metastatic breast cancers, enriched with triple-negative breast cancers (TNBCs; 60%). The expression of epithelial-to-mesenchymal transition-regulating transcription factors Sip1, Zeb1 and vimentin had previously been determined in the same material. RESULTS: In multivariate analysis, strong cytoplasmic claudin 3 expression was associated with poor relapse-free survival (RFS), disease-free survival, distant disease-free survival, breast cancer-specific survival and overall survival among TNBC patients (for RFS, RR 5.202, 95% CI 1.210-22.369, p = 0.027, vs. T-class, RR 0.663, 95% CI 0.168-2.623, p = 0.558, and N-class, RR 3.940, 95% CI 0.933-16.631, p = 0.062). Cytoplasmic claudin 3 expression was also associated with strong nuclear Sip1 expression (p = 0.000053), TNBC phenotype (p = 0.012) and within them, non-basal-like phenotype (p = 0.026). Cytoplasmic claudin 7 was associated with dismal RFS (RR 6.328, 95% CI 1.401-28.593, p = 0.016, vs. T-class, RR 0.692, 95% CI 0.242-1.982, p = 0.493, and N-class, RR 2.981, 95% CI 1.1016-8.749, p = 0.047). Low cytoplasmic expression of claudins 3, 4 and 7 together also predicted poor RFS (RR 6.070, 95% CI 1.347-27.363, p = 0.019, vs. T-class, RR 0.677, 95% CI 0.237-1.934, p = 0.467, and N-class, RR 3.167, 95% CI 1.079-9.290, p = 0.036). CONCLUSIONS: Immunohistochemical expression levels of cytoplasmic claudins 3 and 7 appear to be novel prognostic factors in TNBC.

Development of a Quenchbody for the Detection and Imaging of the Cancer-Related Tight-Junction-Associated Membrane Protein Claudin.

Claudins (CLs) are membrane proteins found in tight junctions and play a major role in establishing the intercellular barrier. However, some CLs are abnormally overexpressed on tumor cells and are valid clinical biomarkers for cancer diagnosis. Here, we constructed antibody Fab fragment-based Quenchbodies (Q-bodies) as effective and reliable fluorescent sensors for detecting and visualizing CLs on live tumor cells. The variable region genes for anti-CL1 and anti-CL4 antibodies were used to express recombinant Fab fragments, and clones recognizing CL4 with high affinity were selected for making Q-bodies. When two fluorescent dyes were conjugated to the N-terminal tags attached to the Fab, the fluorescent signal was significantly increased after adding nanomolar-levels of purified CL4. Moreover, addition of the Q-body to CL4-expressing cells including CL4-positive cancer cells led to a clear fluorescence signal with low background, even without washing steps. Our findings suggested that such Q-bodies would serve as a potent tool for specifically illuminating membrane targets expressed on cancer cells, both in vitro and in vivo.

Expression of Oligodendrocyte Marker during Peripheral-Central Transitional Zone Formation of the Postnatal Mouse Cochlear Nerve.

Objective To better understand oligodendrocyte protein expression along the mouse cochlear nerve in postnatal mice. Study Design In vivo murine study. Setting Research laboratory. Subjects and Methods Swiss Webster mice used at multiple postnatal days (0, 1, 3, 5, 7, 8, 10, 14, 30, and 60). There were 5 replicates at each postnatal day. Cryosection was done to produce sections that included the cochlear nucleus, cochlear nerve, and cochlea in a single sample. Differential interference contrast (DIC) microscopy and immunofluorescence with antibodies specific to the oligodendrocyte protein Olig2 were used to study the cochlear nerve of Swiss Webster mice at postnatal days. Results The myelination of central nervous system projections initiates in close proximity to the peripheral nervous system-central nervous system transitional zone (PCTZ), and oligodendrocytes in neonatal mice are seen with immunohistochemistry peripheral to the DIC-PCTZ interface. Conclusions As the PCTZ migrates from the brain to the cochlea, oligodendrocytes are a part of peripheral extension of central nervous system tissue along the cochlear nerve. Expression of oligodendrocyte marker Oligo2 was observed peripherally to the formation of PCTZ, as determined by DIC microscopy.

Anti-claudin 18.2 antibody as new targeted therapy for advanced gastric cancer.

Targeted therapy and immunotherapy have revolutionized treatment of various cancers in the past decade. Despite targeted therapy with trastuzumab in Her2-positive gastric cancer patients, survival has been dismal, mostly due to disease progression and toxicity related to the treatments. One area of active development is looking for ideal monoclonal antibodies (IMAB) specific to the proteins only on the tumor and hence avoiding unnecessary side effects. Claudin proteins with isoform 2 are one such protein, specific for several cancers, particularly gastric cancer and its metastases, leading to the development of anti-claudin 18.2 specific antibody, claudiximab. This review will highlight the latest development of claudiximab as first in class IMAB for the treatment of gastric cancer.