Zonula occludens-1, occludin, and E-cadherin protein expression in biliary tract cancers

N-Cadherin Distinguishes Intrahepatic Cholangiocarcinoma from Liver Metastases of Ductal Adenocarcinoma of the Pancreas

Carcinomas of the pancreatobiliary system confer an especially unfavorable prognosis. The differential diagnosis of intrahepatic cholangiocarcinoma (iCCA) and its subtypes versus liver metastasis of ductal adenocarcinoma of the pancreas (PDAC) is clinically important to allow the best possible therapy. We could previously show that E-cadherin and N-cadherin, transmembrane glycoproteins of adherens junctions, are characteristic features of hepatocytes and cholangiocytes. We therefore analyzed E-cadherin and N-cadherin in the embryonally related epithelia of the bile duct and pancreas, as well as in 312 iCCAs, 513 carcinomas of the extrahepatic bile ducts, 228 gallbladder carcinomas, 131 PDACs, and precursor lesions, with immunohistochemistry combined with image analysis, fluorescence microscopy, and immunoblots. In the physiological liver, N-cadherin colocalizes with E-cadherin in small intrahepatic bile ducts, whereas larger bile ducts and pancreatic ducts are positive for E-cadherin but contain decreasing amounts of N-cadherin. N-cadherin was highly expressed in most iCCAs, whereas in PDACs, N-cadherin was negative or only faintly expressed. E- and N-cadherin expression in tumors of the pancreaticobiliary tract recapitulate their expression in their normal tissue counterparts. N-cadherin is a helpful marker for the differential diagnosis between iCCA and PDAC, with a specificity of 96% and a sensitivity of 67% for small duct iCCAs and 50% for large duct iCCAs.

Angiotensin II type 1 receptor localizes at the blood-bile barrier in humans and pigs

Animal models and clinical studies suggest an influence of angiotensin II (AngII) on the pathogenesis of liver diseases via the renin–angiotensin system. AngII application increases portal blood pressure, reduces bile flow, and increases permeability of liver tight junctions. Establishing the subcellular localization of angiotensin II receptor type 1 (AT1R), the main AngII receptor, helps to understand the effects of AngII on the liver. We localized AT1R in situ in human and porcine liver and porcine gallbladder by immunohistochemistry. In order to do so, we characterized commercial anti-AT1R antibodies regarding their capability to recognize heterologous human AT1R in immunocytochemistry and on western blots, and to detect AT1R using overlap studies and AT1R-specific blocking peptides. In hepatocytes and canals of Hering, AT1R displayed a tram-track-like distribution, while in cholangiocytes AT1R appeared in a honeycomb-like pattern; i.e., in liver epithelia, AT1R showed an equivalent distribution to that in the apical junctional network, which seals bile canaliculi and bile ducts along the blood–bile barrier. In intrahepatic blood vessels, AT1R was most prominent in the tunica media. We confirmed AT1R localization in situ to the plasma membrane domain, particularly between tight and adherens junctions in both human and porcine hepatocytes, cholangiocytes, and gallbladder epithelial cells using different anti-AT1R antibodies. Localization of AT1R at the junctional complex could explain previously reported AngII effects and predestines AT1R as a transmitter of tight junction permeability.

IL-13 as Target to Reduce Cholestasis and Dysbiosis in Abcb4 Knockout Mice

The Th2 cytokine IL-13 is involved in biliary epithelial injury and liver fibrosis in patients as well as in animal models. The aim of this study was to investigate IL-13 as a therapeutic target during short term and chronic intrahepatic cholestasis in an Abcb4-knockout mouse model (Abcb4^-/-). Lack of IL-13 protected Abcb4^-/- mice transiently from cholestasis. This decrease in serum bile acids was accompanied by an enhanced excretion of bile acids and a normalization of fecal bile acid composition. In Abcb4^-/-/IL-13^-/- double knockout mice, bacterial translocation to the liver was significantly reduced and the intestinal microbiome resembled the commensal composition in wild type animals. In addition, 52-week-old Abcb4^-/-IL-13^-/- mice showed significantly reduced hepatic fibrosis. Abcb4^-/- mice devoid of IL-13 transiently improved cholestasis and converted the composition of the gut microbiota towards healthy conditions. This highlights IL-13 as a potential therapeutic target in biliary diseases.

Tight Junction Proteins and the Biology of Hepatobiliary Disease

Tight junctions (TJ) are intercellular adhesion complexes on epithelial cells and composed of integral membrane proteins as well as cytosolic adaptor proteins. Tight junction proteins have been recognized to play a key role in health and disease. In the liver, TJ proteins have several functions: they contribute as gatekeepers for paracellular diffusion between adherent hepatocytes or cholangiocytes to shape the blood-biliary barrier (BBIB) and maintain tissue homeostasis. At non-junctional localizations, TJ proteins are involved in key regulatory cell functions such as differentiation, proliferation, and migration by recruiting signaling proteins in response to extracellular stimuli. Moreover, TJ proteins are hepatocyte entry factors for the hepatitis C virus (HCV)—a major cause of liver disease and cancer worldwide. Perturbation of TJ protein expression has been reported in chronic HCV infection, cholestatic liver diseases as well as hepatobiliary carcinoma. Here we review the physiological function of TJ proteins in the liver and their implications in hepatobiliary diseases.

Vasoactive Intestinal Peptide Derived From Liver Mesenchymal Cells Mediates Tight Junction Assembly in Mouse Intrahepatic Bile Ducts

Formation of intrahepatic bile ducts (IHBDs) proceeds in accordance with their microenvironment. Particularly, mesenchymal cells around portal veins regulate the differentiation and ductular morphogenesis of cholangiocytes in the developing liver; however, further studies are needed to fully understand the arrangement of IHBDs into a continuous hierarchical network. This study aims to clarify the interaction between biliary and liver mesenchymal cells during IHBD formation. To identify candidate factors contributing to this cell–cell interaction, mesenchymal cells were isolated from embryonic day 16.5 matrix metalloproteinase 14 (MMP14)‐deficient (knockout [KO]) mice livers, in which IHBD formation is retarded, and compared with those of the wild type (WT). WT mesenchymal cells significantly facilitated the formation of luminal structures comprised of hepatoblast‐derived cholangiocytes (cholangiocytic cysts), whereas MMP14‐KO mesenchymal cells failed to promote cyst formation. Comprehensive analysis revealed that expression of vasoactive intestinal peptide (VIP) was significantly suppressed in MMP14‐KO mesenchymal cells. VIP and VIP receptor 1 (VIPR1) were mainly expressed in periportal mesenchymal cells and cholangiocytic progenitors during IHBD development, respectively, in vivo. VIP/VIPR1 signaling significantly encouraged cholangiocytic cyst formation and up‐regulated tight junction protein 1, cystic fibrosis transmembrane conductance regulator, and aquaporin 1, in vitro. VIP antagonist significantly suppressed the tight junction assembly and the up‐regulation of ion/water transporters during IHBD development in vivo. In a cholestatic injury model of adult mice, exogenous VIP administration promoted the restoration of damaged tight junctions in bile ducts and improved hyperbilirubinemia. Conclusion: VIP is produced by periportal mesenchymal cells during the perinatal stage. It supports bile duct development by establishing tight junctions and up‐regulating ion/water transporters in cholangiocytes. VIP contributes to prompt recovery from cholestatic damage through the establishment of tight junctions in the bile ducts.

Low Expression of Occludin in the Melanoma Patient

BACKGROUND & OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Decreased expression of ZO-1 is associated with tumor metastases in liver cancer

Certain types of cancer exhibit downregulated expression of zonula occludens-1 (ZO-1), which serves an important function in tumor progression; however, the underlying molecular mechanisms that lead to this downregulation in cancer remain unclear. In the present study, the expression of ZO-1 in liver cancer (LC) tissues was investigated. Western blot and reverse transcription-quantitative polymerase chain reaction assays were used to detect the expression of ZO-1 protein and mRNA in LC tissues and paired adjacent non-tumorous tissues. The results indicated that, compared with non-tumorous tissues, the expression of ZO-1 was significantly downregulated at the protein (P<0.001) and mRNA (P=0.006) levels in LC tissue samples. In addition, various cellular and molecular methods were applied, including MTT, colony formation, flow cytometry and Transwell assays. The results indicated that overexpression of ZO-1 inhibited cell viability, proliferation and migration, and induced G₀/G₁ phase arrest in vitro.

Cholangiocarcinoma: Classification, Histopathology and Molecular Carcinogenesis

Cholangiocarcinoma (CC) is the second most common tumor of the liver, originating from the biliary system with increasing incidence and mortality worldwide. Several new classifications review the significance of tumor localization, site of origin, proliferation and biomarkers in the intrahepatic, perihilar and distal forms of the lesion. Based on growth pattern mass-forming, periductal-infiltrating, intraductal, undefined and mixed types are differentiated. There are further subclassifications which are applied for the histological features, in particular for intrahepatic CC. Recognition of the precursors and early lesions of CC including biliary intraepithelial neoplasia (BilIN), intraductal papillary neoplasm of the bile ducts (IPNB), biliary mucinous cystic neoplasm (MCNB) and the candidate precursors, such as bile duct adenoma and von Meyenburg complex is of increasing significance. In addition to the previously used biliary markers detected by immunohistochemistry, several new markers have been added to the differentiation of both the benign and malignant lesions, which can be used to aid in the subclassification in association with the outcome of CC. Major aspects of biliary carcinogenesis have been revealed, yet, the exact way of this diverse process is still unclear. The factors contributing to molecular cholangiocarcinogenesis include various risk factors, different anatomical localizations, multiple cellular origins, genetic and epigenetic alterations, tumor microenvironment, heterogeneity and clonal evolution. Driver mutations have been identified, implying that they are optimal candidates for targeted therapy. The most promising therapeutic candidates have entered clinical trials.

Abnormally expressed JunB transactivated by IL-6/STAT3 signaling promotes uveal melanoma aggressiveness via epithelial-mesenchymal transition

Uveal melanoma (UM) is the most common primary intraocular tumor in adults, and it carries a high risk of metastasis and mortality. Various proinflammatory cytokines have been found to be significantly increased in the aqueous humor or vitreous fluid of UM patients; however, the role of these cytokines in UM metastasis remains elusive. In the present study, we found that long-term interleukin (IL)-6 exposure promoted the migration and invasion of UM cells, diminished cell–cell adhesion, and enhanced focal adhesion. Moreover, IL-6 treatment decreased the membranous epithelial marker TJP1 and increased the cytoplasmic mesenchymal marker Vimentin. Further investigation demonstrated that JunB played a critical role in IL-6-induced UM epithelial–mesenchymal transition (EMT). In UM cells, the expression of JunB was significantly up-regulated during the IL-6-driven EMT process. Additionally, JunB induction occurred at the transcriptional level in a manner dependent on phosphorylated STAT3, during which activated STAT3 directly bound to the JunB promoter. Importantly, the knockdown of STAT3 prevented the IL-6-induced EMT phenotype as well as cell migration and invasion, whereas JunB overexpression recovered the attenuated aggressiveness of UM cells. Similarly, with IL-6 stimulation, the stable overexpression of JunB strengthened the migratory and invasive capabilities of UM cells and induced the EMT-promoting factors (Snail, Twist1, matrix metalloproteinase (MMP)-2, MMP-14, and MMP-19). Analysis of The Cancer Genome Atlas (TCGA) database indicated that JunB was positively correlated with IL-6 and STAT3 in UM tissues. The present study proposes an IL-6/STAT3/JunB axis leading to UM aggressiveness by EMT, which illustrates the negative side of inflammatory response in UM metastasis.

MicroRNA‑103 regulates tumorigenesis in colorectal cancer by targeting ZO‑1

Given the emerging role of microRNAs (miRs) in cancer progression, the present study investigated the role and underlying mechanism of miR-103 in colorectal cancer (CRC). Reverse transcription-quantitative polymerase chain reaction was conducted to quantify the expression levels of miR-103 in clinical specimens and cell lines. The role of miR-103 in CRC was examined using MTT, colony formation and transwell assays. In addition, a luciferase reporter assay was used to confirm an associated between the 3′ untranslated region of zonula occuldens-1 (ZO-1) and miR-103. The results demonstrated that miR-103 was upregulated in CRC. Overexpression of miR-103 promoted CRC cell proliferation and migration in vitro, whereas downregulation of miR-103 inhibited cell proliferation and migration. ZO-1 was identified as a direct target of miR-103, revealing its expression to be inversely correlated with miR-103 expression in CRC samples. In conclusion, the present study revealed that miR-103 has strong tumor-promoting effects via of targeting ZO-1 in CRC and has potential development of miRNA-based targeted approaches for the treatment of CRC.

Epithelial-mesenchymal transition in cholangiocarcinoma: From clinical evidence to regulatory networks

Cholangiocarcinoma (CCA) is an aggressive tumor with a poor prognosis due to its late clinical presentation and the lack of effective non-surgical therapies. Unfortunately, most of the patients are not eligible for curative surgery owing to the presence of metastases at the time of diagnosis. Therefore, it is important to understand the steps leading to cell dissemination in patients with CCA. To metastasize from the primary site, cancer cells must acquire migratory and invasive properties by a cell plasticity-promoting phenomenon known as epithelial-mesenchymal transition (EMT). EMT is a reversible dynamic process by which epithelial cells gradually adopt structural and functional characteristics of mesenchymal cells, and has lately become a centre of attention in the field of metastatic dissemination. In the present review, we aim to provide an extensive overview of the current clinical data and the prognostic value of different EMT markers that have been analysed in CCA. We summarize all the regulatory networks implicated in EMT from the membrane receptors to the main EMT-inducing transcription factors (SNAIL, TWIST and ZEB). Furthermore, since a tumor is a complex structure not exclusively formed by tumor cells, we also address the prominent role of the main cell types of the desmoplastic stroma that characterizes CCA in the regulation of EMT. Finally, we discuss the therapeutic considerations and difficulties faced to develop an effective anti-EMT treatment due to the redundancies and bypasses among the pathways regulating EMT.

Reversed cellular polarity in primary cutaneous mucinous carcinoma: A study on tight junction protein expression in sweat gland tumors

Primary cutaneous mucinous carcinoma (PCMC) is a rare sweat gland tumor characterized by the presence of abundant mucin around the tumor islands, but the molecular mechanisms for this structure are not well elucidated. Because mucin is epithelial in nature, it is likely to be produced by epithelial tumor cells, not by surrounding stromal cells. We hypothesized that the abundant mucin is a result of reversed cellular polarity of the tumor. To test this hypothesis, we conducted an immunohistological study to investigate expression of tight junction (TJ) proteins occludin and ZO-1 in PCMC, as well as in normal sweat glands and other sweat gland tumors. Dot-like or linear expression of TJ proteins was observed at ductal structures of sweat glands, and ductal or cystic structures of related tumors. In PCMC, however, TJ protein expression was clearly visible at the edges of tumor cell islands. This study provides evidence to show that the characteristic histological structure of PCMC is caused by inverse polarization of the tumor cells, and that TJ proteins are useful markers of ductal differentiation in sweat gland tumors.

[High frequency of ancestral allele of the TJP1 polymorphism rs2291166 in Mexican population, conformational effect and applications in surgery and medicine]

BACKGROUND

TJP1 gene encodes a ZO-1 protein that is required for the recruitment of occludins and claudins in tight junction, and is involved in cell polarisation. It has different variations, the frequency of which has been studied in different populations. In Mexico there are no studies of this gene. These are required because their polymorphisms can be used in studies associated with medicine and surgery. Therefore, the aim of this study was to estimate the frequency of alleles and genotypes of rs2291166 gene polymorphism TJP1 in Mexico Mestizos population, and to estimate the conformational effect of an amino acid change.

MATERIAL AND METHODS

A total of 473 individuals were included. The rs2291166 polymorphism was identified PASA PCR-7% PAGE, and stained with silver nitrate. The conformational effect of amino acid change was performed in silico, and was carried out with servers ProtPraram Tool and Search Database with Fasta.

RESULTS

The most frequent allele in the two populations is the ancestral allele (T). A genotype distribution similar to other populations was found. The polymorphism is in Hardy-Weinberg, p>0.05. Changing aspartate to alanine produced a conformational change.

CONCLUSIONS

The study reveals a high frequency of the ancestral allele at rs2291166 polymorphism in the Mexican population.

RNA sequencing supports distinct reactive oxygen species-mediated pathways of apoptosis by high and low size mass fractions of Bay leaf (Lauris nobilis) in HT-29 cells

Anti-proliferative and pro-apoptotic effects of Bay leaf (Laurus nobilis) in mammalian cancer and HT-29 adenocarcinoma cells have been previously attributed to effects of polyphenolic and essential oil chemical species. Recently, we demonstrated differentiated growth-regulating effects of high (HFBL) versus low molecular mass (LFBL) aqueous fractions of bay leaf and now confirm by comparative effects on gene expression, that HFBL and LFBL suppress HT-29 growth by distinct mechanisms. Induction of intra-cellular lesions including DNA strand breakage by extra-cellular HFBL, invoked the hypothesis that iron-mediated reactive oxygen species with capacity to penetrate cell membrane, were responsible for HFBL-mediated effects, supported by equivalent effects of HFBL in combination with γ radiation. Activities of HFBL and LFBL were interpreted to reflect differentiated responses to iron-mediated reactive oxygen species (ROS), occurring either outside or inside cells. In the presence of LFBL, apoptotic death was relatively delayed compared with HFBL. ROS production by LFBL mediated p53-dependent apoptosis and recovery was suppressed by promoting G1/S phase arrest and failure of cellular tight junctions. In comparison, intra-cellular anti-oxidant protection exerted by LFBL was absent for extra-cellular HFBL (likely polysaccharide-rich), which potentiated more rapid apoptosis by producing DNA double strand breaks. Differentiated effects on expression of genes regulating ROS defense and chromatic condensation by LFBL versus HFBL, were observed. The results support ferrous iron in cell culture systems and potentially in vivo, can invoke different extra-cellular versus intra-cellular ROS-mediated chemistries, that may be regulated by exogenous, including dietary species.

Bile duct epithelial tight junctions and barrier function

Bile ducts play a crucial role in the formation and secretion of bile as well as excretion of circulating xenobiotic substances. In addition to its secretory and excretory functions, bile duct epithelium plays an important role in the formation of a barrier to the diffusion of toxic substances from bile into the hepatic interstitial tissue. Disruption of barrier function and toxic injury to liver cells appear to be involved in the pathogenesis of a variety of liver diseases such as primary sclerosing cholangitis, primary biliary cirrhosis and cholangiocarcinoma. Although the investigations into understanding the structure and regulation of tight junctions in gut, renal and endothelial tissues have expanded rapidly, very little is known about the structure and regulation of tight junctions in the bile duct epithelium. In this article we summarize the current understanding of physiology and pathophysiology of bile duct epithelium, the structure and regulation of tight junctions in canaliculi and bile duct epithelia and different mechanisms involved in the regulation of disruption and protection of bile duct epithelial tight junctions. This article will make a case for the need of future investigations toward our understanding of molecular organization and regulation of canalicular and bile duct epithelial tight junctions.

Upregulated ZO-1 correlates with favorable survival of gastrointestinal stromal tumor

Zonula occludens-1 (ZO-1) is a membrane-scaffolding protein that plays an important role in maintaining tight-junction integrity, which is disrupted in many invasive cancers and intestinal diseases. However, the expression of ZO-1 in gastrointestinal stromal tumor (GIST) and its relationship with clinical characteristics of this disease remain poorly understood. In this study, immunohistochemical analysis using tissue microarray was employed to evaluate the expression of ZO-1 in GIST and to investigate the relationship between its expression and GIST prognosis. High ZO-1 expression was displayed in 71.8 % of GIST patients, which was related to tumor diameter (p < 0.05). The Kaplan-Meier method and log-rank test indicated that high ZO-1 expression, small tumor diameter, tumor position in the esophagus, and a borderline-to-intermediate tumor grade displayed significant correlations with longer survival of GIST patients. The data suggest that ZO-1 expression is correlated with malignant phenotypes of GIST and it may serve as a favorable prognostic factor for GIST. These results also support a role for ZO-1 as a tumor-suppressor gene in GIST.

Clinicopathological features and CCT2 and PDIA2 expression in gallbladder squamous/adenosquamous carcinoma and gallbladder adenocarcinoma

Background

Gallbladder cancer (GBC) is a relatively uncommon carcinoma among gastrointestinal cancers and usually has a rather poor prognosis. The most common subtype of GBC is adenocarcinoma (AC), which accounts for about 90% of GBC. Squamous carcinoma/adenosquamous carcinoma (SC/ASC) are comparatively rare histopathological subtypes of GBC. The clinicopathological features and biological behaviors of SC/ASC have not been well-characterized. No molecular biomarkers are currently available for predicting the progression, metastasis, and prognosis of the SC/ASC subtype of GBC.

Methods

We examined the expression levels of CCT2 and PDIA3 by immunohistochemistry (IHC) staining in human GBC tissue samples collected from 46 patients with SC/ASC and evaluated the clinicopathological significance of both CCT2 and PDIA3 expression in the SC/ASC subtypes of GBC by Kaplan-Meier analysis and multivariate Cox regression analysis. For comparison, we included specimens from 80 AC patients in our study to investigate the specificity of CCT2 and PDIA3 expression in GBC subtypes.

Results

We found that the positive expression of CCT2 and PDIA3 was significantly associated with clinicopathological features of both SC/ASC and AC specimens, including high TNM stage and lymph node metastasis. Univariate analysis revealed that the two-year survival rate was significantly lower for patients with positive expression of CCT2 and PDIA3 than for those with negative expression. Multivariate analysis also indicated that the positive expression of CCT2 and PDIA3 was negatively correlated with poor postoperative patient survival and positively correlated with high mortality.

Conclusions

Our study suggests that positive expression of CCT2 or PDIA3 is associated with tumor progression and the clinical behavior of gallbladder carcinoma. Therefore, CCT2 and PDIA3 could be potentially important diagnostic and prognostic biomarkers for both SC/ASC and AC subtypes of GBC.

Occludin is involved in adhesion, apoptosis, differentiation and Ca2+-homeostasis of human keratinocytes: implications for tumorigenesis

Tight junction (TJ) proteins are involved in a number of cellular functions, including paracellular barrier formation, cell polarization, differentiation, and proliferation. Altered expression of TJ proteins was reported in various epithelial tumors. Here, we used tissue samples of human cutaneous squamous cell carcinoma (SCC), its precursor tumors, as well as sun-exposed and non-sun-exposed skin as a model system to investigate TJ protein alteration at various stages of tumorigenesis. We identified that a broader localization of zonula occludens protein (ZO)-1 and claudin-4 (Cldn-4) as well as downregulation of Cldn-1 in deeper epidermal layers is a frequent event in all the tumor entities as well as in sun-exposed skin, suggesting that these changes result from chronic UV irradiation. In contrast, SCC could be distinguished from the precursor tumors and sun-exposed skin by a frequent complete loss of occludin (Ocln). To elucidate the impact of down-regulation of Ocln, we performed Ocln siRNA experiments in human keratinocytes and uncovered that Ocln downregulation results in decreased epithelial cell-cell adhesion and reduced susceptibility to apoptosis induction by UVB or TNF-related apoptosis-inducing ligand (TRAIL), cellular characteristics for tumorigenesis. Furthermore, an influence on epidermal differentiation was observed, while there was no change of E-cadherin and vimentin, markers for epithelial-mesenchymal transition. Ocln knock-down altered Ca²⁺-homeostasis which may contribute to alterations of cell-cell adhesion and differentiation. As downregulation of Ocln is also seen in SCC derived from other tissues, as well as in other carcinomas, we suggest this as a common principle in tumor pathogenesis, which may be used as a target for therapeutic intervention.

Mucinous carcinomas of the gallbladder: clinicopathologic analysis of 15 cases identified in 606 carcinomas

CONTEXT

There are virtually no data in the literature regarding the incidence, patterns, and clinicopathologic characteristics of mucinous carcinomas (MCs) of the gallbladder (GB).

OBJECTIVE

To determine the incidence of mucinous differentiation in invasive GB carcinomas and the clinicopathologic characteristics of those that qualify as MC.

DESIGN

Primary invasive GB carcinomas (n  =  606) were reviewed for mucinous differentiation. Some degree of mucin production was identified in 40 cases (6.6%); however, only 15 (2.5%) were qualified for the World Health Organization definition of MC (stromal mucin deposition constituting >50% of the tumor).

RESULTS

The mean age was 65 years, and the female to male ratio was 1.1 (versus 3.9 for conventional pancreatobiliary-type GB adenocarcinomas; P  =  .04). A significant proportion of the cases (8 of 12, 67%) presented with the clinical picture and intraoperative findings that were interpreted as acute cholecystitis. Mean and median tumor sizes were larger than those of conventional adenocarcinomas (4.8 and 3.4 cm versus 2.9 and 2.5 cm, respectively; P  =  .01). Most (13 of 15, 87%) cases presented with pT3 tumors (versus 48% for ordinary GB carcinomas; P  =  .01). Two cases had almost an exclusive colloid pattern (>90% composed of well-defined stromal mucin nodules that contained scanty carcinoma cells, most of which were floating within the mucin). Eight cases were of mixed-mucinous type, showing a mixture of colloid and noncolloid patterns. Five others had prominent signet-ring cells, both floating within the mucin (which constituted >50% of the tumor by definition) and infiltrating into the stroma as individual signet-ring cells in some areas. Immunohistochemical analysis performed on the 7 cases that had available tissue revealed CK7 in 4 of 7 (57%), CK20 in 2 of 7 (29%), MUC1 in 4 of 7 (57%), MUC2 in 6 of 7 (86%), CDX2 in 1 of 7 (14%), MUC5AC in 6 of 7 (86%), MUC6 in 0 of 7 (0%), and loss of E-cadherin in 6 of 7 (86%). The MLH1 and MSH2 were retained in 6 of 7 cases (100%). Follow-up information was available for 13 cases: 11 (85%) died of disease (1-37 months) and 2 (15%) were alive (23 months and 1 month). Overall survival of MCs was significantly worse than that of conventional adenocarcinomas (13 versus 26 months; P  =  .01); however, that did not seem to be independent of stage.

CONCLUSIONS

Mucinous carcinomas constitute 2.5% of GB carcinomas. They present with an acute cholecystitis-type picture. Most MCs are a mixed-mucinous, not pure colloid, type. They are typically large and advanced tumors at the time of diagnosis and thus exhibit more-aggressive behavior than do ordinary GB carcinomas. Immunophenotypically, they differ from conventional GB adenocarcinomas by MUC2 positivity, from intestinal carcinomas by an often inverse CK7/20 profile, from pancreatic mucinous carcinomas by CDX2 negativity, and from mammary colloid carcinomas by a lack of MUC6. Unlike gastrointestinal MCs, they appear to be microsatellite stable.

Biomarkers of epithelial-mesenchymal transition in squamous cell carcinoma

An understanding of the process by which tumor cells destroy the basement membrane of the surface epithelium, invade, and metastasize is essential to the development of novel treatment of head and neck squamous cell carcinoma (HNSCC). In recent years, there has been increased interest in the role of epithelial-mesenchymal transition (EMT) in invasion. EMT is a process that describes the development of motile, mesenchymal-like cells from non-motile parent epithelial cells. There are 3 known types of EMT that mediate development, wound healing, and carcinogenesis. This review summarizes studies of known EMT biomarkers in the context of HNSCC progression. The biomarkers discussed come from a wide range of proteins, including cell-surface proteins (E-cadherin, N-cadherin, and Integrins), cytoskeletal proteins (α-Smooth Muscle Actin, Vimentin, and β-catenin), extracellular matrix proteins (Collagens, Fibronectin, and Laminin), and transcription factors (SNAIL1, SNAIL2, TWIST, and LEF-1). Overall, the findings of these studies suggest that EMT mediates HNSCC progression. The mechanistic role of the EMT markers that have been associated with HNSCC should be more clearly defined if new anti-HNSCC therapies to block EMT progression are to be developed.

Differential expression of PDZ domain-containing proteins in human diseases - challenging topics and novel issues

The general features of the PDZ domain structure and functions have been extensively studied during the last decade. PDZ domains are generally present in proteins that are involved in multiple interactions to assemble functional protein complexes that control key cellular processes. One of the best characterized functions of PDZ domain-containing proteins is control of epithelial cell polarity and cell-cell contacts. In the present review, we summarize the current knowledge on regulation of expression of certain PDZ polarity proteins localized at the intercellular junctions. In addition, we provide a critical overview of recent findings regarding the role of these proteins during development of human diseases. Complete understanding of these issues is valuable for the design of novel therapeutic intervention for common pathologies, such as cancer.

MTDH and EphA7 are markers for metastasis and poor prognosis of gallbladder adenocarcinoma

Gallbladder cancer is an aggressive cancer with extremely poor prognosis. Over 90% of patients are diagnosed at an advanced, inoperable stage with metastasis and invasion to other organs. In this study, the expression of metadherin (MTDH) and erythropoietin-producing hepatoma-amplified sequence (Eph) receptor A7 (EphA7) in 96 benign and 108 malignant lesions of gallbladder was determined by immunohistochemistry, and their correlations with pathological features and prognosis were analyzed. Positive expression of EphA7 and MTDH was significantly higher in gallbladder adenocarcinoma than in benign lesions. In adenocarcinoma, the positive expression of EphA7 and MTDH was significantly associated with differentiation, tumor mass, lymphnode metastasis, invasion, and overall survival. Multivariate Cox regression analysis suggested that positive expression of EphA7 and MTDH was an independent poor-prognostic predictor in gallbladder adenocarcinoma. The elevated expression of EphA7 and/or MTDH is closely related to carcinogenesis, progression, clinical biological behaviors, and prognosis of gallbladder adenocarcinoma.

Hypertonic stress promotes the upregulation and phosphorylation of zonula occludens 1

Tight junction molecules form a barrier between adjacent cells and mediate the cells' ability to develop membranes that constitute boundaries of different compartments within the body. Membranes with selective ion and water passage are important for the electrolyte and water homeostasis in the kidney. Due to their role in the urinary concentration process, renal medullary cells are exposed to hyperosmotic stress. Therefore, we were interested in the question of how mouse inner medullary collecting duct cells (mIMCD3) manage to maintain their cell-cell contacts, despite hypertonicity-induced cell shrinkage. Employing mRNA expression analysis, we found that the zonula occludens type 1 (Zo-1), multi-PDZ domain protein 1 (MUPP1) and cortactin mRNA levels were upregulated in a tonicity-dependent manner. Using Western blot analysis, immunoprecipitation and immunofluorescence, we show that the Zo-1 protein is upregulated, phosphorylated and linked to the actin cytoskeleton in response to hypertonic stress. After cell exposure to hypertonicity, rearrangement of the actin cytoskeleton resulted in a stronger colocalization of actin fibres with Zo-1. Urea, which generates hyperosmolality, but no transcellular gradient, did not induce changes in Zo-1 protein expression or actin rearrangement. This data indicates that Zo-1 is a response protein to inner medullary tonicity and that extracellular stressors can promote Zo-1 protein expression, tyrosine phosphorylation and cytoskeleton association.

Epithelial cell polarity and tumorigenesis: new perspectives for cancer detection and treatment

Loss of cell-cell adhesion and cell polarity is commonly observed in tumors of epithelial origin and correlates with their invasion into adjacent tissues and formation of metastases. Growing evidence indicates that loss of cell polarity and cell-cell adhesion may also be important in early stage of cancer. In first part of this review, we delineate the current understanding of the mechanisms that establish and maintain the polarity of epithelial tissues and discuss the involvement of cell polarity and apical junctional complex components in tumor pathogenesis. In the second part we address the clinical significance of cell polarity and junctional complex components in cancer diagnosis and prognosis. Finally, we explore their potential use as therapeutic targets in the treatment of cancer.

Identification of PEG10 and TSG101 as carcinogenesis, progression, and poor-prognosis related biomarkers for gallbladder adenocarcinoma

PEG10 is a transcriptional factor while TSG101 is involved in numerous cellular processes, including apoptotic resistance. Overexpression of PEG10 and TSG101 were observed in a variety of human cancers. However, their expression and clinical significance in gallbladder cancer (GBC) have not yet been identified. To understand the tumor biology of GBC at the molecular level, we examined PEG10 and TSG101 expression in 108 adenocarcinomas, 15 gallbladder polyps, 35 chronic cholecystitis tissues, and 46 peritumoral tissues by using immunohistochemistry. Overexpression of PEG10 and TSG101 was detected in gallbladder adenocarcinoma (48.1% and 47.2%, respectively). Conversely, there was less expression detected in the peritumoral tissues (19.6%), adenomatous polyps (13.3%), and gallbladder epithelium with chronic cholecystitis (5.1%) (p < 0.01, p < 0.05, and p < 0.01, respectively). Notably, the benign lesions with positive PEG10 and/or TSG101 expression showed moderately or severely atypical hyperplasia in gallbladder epithelium. The overexpression of PEG10 and TSG101 was significantly associated with differentiation, tumor mass, lymph node metastasis and invasion of adenocarcinoma. Univariate Kaplan-Meier analysis showed that overexpression of PEG10 (p = 0.041) and TSG101 (p = 0.025) was closely associated with decreased overall survival. Multivariate Cox regression analysis revealed that positive expression of PEG10 (p = 0.036) or TSG101 (p = 0.022) is a predictor of poor prognosis in gallbladder adenocarcinoma. Our study suggested that overexpression of PEG10 and TSG101 might be closely related to the carcinogenesis, progression, clinical biological behaviors, and prognosis of gallbladder adenocarcinoma.

Tight junction-associated signaling pathways modulate cell proliferation in uveal melanoma

PURPOSE

To investigate the role of tight junction (TJ)-associated signaling pathways in the proliferation of uveal melanoma.

METHODS

Human uveal melanoma cell lines overexpressing the TJ molecule blood vessel epicardial substance (Bves) were generated. The effects of Bves overexpression on TJ protein expression, cell proliferation, and cell cycle distribution were quantified. In addition, localization and transcription activity of the TJ-associated protein ZO-1-associated nucleic acid binding protein (ZONAB) were evaluated using immunofluorescence and bioluminescence reporter assays to study the involvement of Bves signaling in cell proliferation-associated pathways.

RESULTS

Bves overexpression in uveal melanoma cell lines resulted in increased expression of the TJ proteins occludin and ZO-1, reduced cell proliferation, and increased sequestration of ZONAB at TJs and reduced ZONAB transcriptional activity.

CONCLUSIONS

TJ proteins are present in uveal melanoma, and TJ-associated signaling pathways modulate cell signaling pathways relevant to proliferation in uveal melanoma.

Estrogen-dependent gallbladder carcinogenesis in LXRbeta-/- female mice

Gallbladder cancer is a highly aggressive disease with poor prognosis that is two to six times more frequent in women than men. The development of gallbladder cancer occurs over a long time (more than 15 y) and evolves from chronic inflammation to dysplasia/metaplasia, carcinoma in situ, and invasive carcinoma. In the present study we found that, in female mice in which the oxysterol receptor liver X receptor-beta (LXRbeta) has been inactivated, preneoplastic lesions of the gallbladder developed and evolved to cancer in old animals. LXRbeta is a nuclear receptor involved in the control of lipid homeostasis, glucose metabolism, inflammation, proliferation, and CNS development. LXRbeta(-/-) female gallbladders were severely inflamed, with regions of dysplasia and high cell density, hyperchromasia, metaplasia, and adenomas. No abnormalities were evident in male mice, nor in LXRalpha(-/-) or LXRalpha(-/-)beta(-/-) animals of either sex. Interestingly, the elimination of estrogens with ovariectomy prevented development of preneoplastic lesions in LXRbeta(-/-) mice. The etiopathological mechanism seems to involve TGF-beta signaling, as the precancerous lesions were characterized by strong nuclear reactivity of phospho-SMAD-2 and SMAD-4 and loss of E-cadherin expression. Upon ovariectomy, E-cadherin was reexpressed on the cell membranes and immunoreactivity of pSMAD-2 in the nuclei was reduced. These findings suggest that LXRbeta in a complex interplay with estrogens and TGF-beta could play a crucial role in the malignant transformation of the gallbladder epithelium.

[Study of claudins and prognostic factors in some gastrointestinal diseases]

Gastrointestinal tumors are highly ranked regarding tumoral mortality worldwide. The development and progression of gastrointestinal (GI) diseases go hand in hand with the changes of tight junctions (TJ). Claudins (CLDN) are the main TJ proteins, showing different expression by the different tissues, with the expressed CLDN profile being representative. I. We explored the changes of CLDN expression in Barrett's esophagus and related adenocarcinoma. CLDN2 and -3 expression in Barrett's esophagus was higher than in normal foveolar epithelium. Adenocarcinoma showed higher CLDN2 and -3 expression compared with normal and Barrett's epithelia. The similar CLDN expression profile of Barrett's esophagus and adenocarcinoma supports their sequential development. II. Gastric intestinal metaplasia showed higher expression of CLDN2, -3 and -4 as compared with normal antral foveolar mucosa. Tumors of small and large bowels exhibited higher CLDN2 expression when compared with normal epithelia. Colorectal adenoma and adenocarcinoma could not be differentiated according to their CLDN profile. Intestinal metaplasias of Barrett's esophagus and stomach show similar CLDN profile to small bowel epithelium. III. Studies on duodenal mucosa in celiac disease in childhood demonstrated CLDN2 and -3 expression to be higher than in normal mucosa. The expression was significantly higher in the distal part of the duodenum samples. This and the serious histological findings suggest that the distal duodenum is more adequate for biopsy testing. IV. Beside the epithelial cells, mesenchymal tumors express intercellular junctional proteins. Expression of claudins in gastrointestinal stromal tumors (GIST) and other mesenchymal neoplasia was also studied. The CLDN profile was found to be representative to the individual tumor. GIST, angiosarcoma, hemangioma, leiomyosarcoma and leiomyoma showed expression of various CLDNs. CLDN2 was detected in all entities. CLDN1, however, was found positive in leiomyosarcoma only. Leiomyoma, on the other hand, expressed only CLDN2. GISTs and leiomyosarcomas showed CLDN2, -3, -4, -5 and -7-expression. The angiogenic tumors revealed CLDN2 and -5 expression. The similar CLDN profile observable in GIST and leiomyosarcoma is suggestive of a histogenetic relationship. Smooth muscle and vessel tumors of different dignity could also be separated from each other based on CLDN profile.