Loss of membrane localization and aberrant nuclear E-cadherin expression correlates with invasion in pancreatic endocrine tumors

Tumor biomarkers for diagnosis, prognosis and targeted therapy

Tumor biomarkers, the substances which are produced by tumors or the body's responses to tumors during tumorigenesis and progression, have been demonstrated to possess critical and encouraging value in screening and early diagnosis, prognosis prediction, recurrence detection, and therapeutic efficacy monitoring of cancers. Over the past decades, continuous progress has been made in exploring and discovering novel, sensitive, specific, and accurate tumor biomarkers, which has significantly promoted personalized medicine and improved the outcomes of cancer patients, especially advances in molecular biology technologies developed for the detection of tumor biomarkers. Herein, we summarize the discovery and development of tumor biomarkers, including the history of tumor biomarkers, the conventional and innovative technologies used for biomarker discovery and detection, the classification of tumor biomarkers based on tissue origins, and the application of tumor biomarkers in clinical cancer management. In particular, we highlight the recent advancements in biomarker-based anticancer-targeted therapies which are emerging as breakthroughs and promising cancer therapeutic strategies. We also discuss limitations and challenges that need to be addressed and provide insights and perspectives to turn challenges into opportunities in this field. Collectively, the discovery and application of multiple tumor biomarkers emphasized in this review may provide guidance on improved precision medicine, broaden horizons in future research directions, and expedite the clinical classification of cancer patients according to their molecular biomarkers rather than organs of origin.

Distribution of E- and N-cadherin in subgroups of non-functioning pituitary neuroendocrine tumours

PURPOSE

Clinically non-functioning pituitary neuroendocrine tumours (NF-PitNETs) present a varying degree of aggressiveness, and reliable prognostic markers are lacking. We aimed to characterise the distribution of E- and N-cadherin in corticotroph, PIT1 and null-cell NF-PitNETs, and link it to the course of the tumours.

METHODS

The distribution of E- and N-cadherin was investigated by immunohistochemistry in a retrospective cohort of 30 tumours of the less common NF-PitNETs (corticotroph (N = 18), PIT1 (N = 8) and null-cell PitNETs (N = 4)). Immunoreactive scores (IRS) were compared to previously presented cohorts of gonadotroph NF-PitNETs (N = 105) and corticotroph functioning PitNETs (N = 17).

RESULTS

We found a low IRS for the extra-cellular domain of E-cadherin (median 0 (IQR 0-0, N = 135)), a medium to high IRS for the intra-cellular domain of E-cadherin (median 6 (IQR 4-9)) and a high IRS for N-cadherin (median 12 (IQR 10.5-12)) throughout the cohort of NF-PitNETs. The corticotroph NF-PitNETs presented a higher IRS for both the extra- and intra-cellular domain of E-cadherin (median 0 (IQR 0-1) and median 9 (IQR 6-12), respectively) than the gonadotroph NF-PitNETs (p < 0.001 for both comparisons). Presence of nuclear E-cadherin was associated with a weaker staining for the intra-cellular domain of E-cadherin (median 4 (IQR 0.5-6) and median 9 (IQR 9-12), for tumours with and without nuclear E-cadherin, respectively), and with a lower rate of re-intervention (p = 0.03).

CONCLUSIONS

Considering our results and the benign course of NF-PitNETs, we suggest that a high N-cadherin and downregulation of membranous E-cadherin are not associated with a more aggressive tumour behaviour in these subgroups of NF-PitNETs.

Wnt Signaling Pathway Is among the Drivers of Liver Metastasis

Liver metastasis, originating either from a primary liver or other cancer types, represent a large cancer-related burden. Therefore, studies that add to better understanding of its molecular basis are needed. Herein, the role of the Wnt signaling pathway in liver metastasis is outlined. Its role in hepatocellular carcinoma (HCC) epithelial-mesenchymal transition (EMT), motility, migration, metastasis formation, and other steps of the metastatic cascade are presented. Additionally, the roles of the Wnt signaling pathway in the liver metastasis formation of colorectal, breast, gastric, lung, melanoma, pancreatic, and prostate cancer are explored. The special emphasis is given to the role of the Wnt signaling pathway in the communication between the many of the components of the primary and secondary cancer microenvironment that contribute to the metastatic outgrowth in the liver. The data presented herein are a review of the most recent publications and advances in the field that add to the idea that the Wnt pathway is among the drivers of liver metastasis and that its targeting could potentially relieve liver metastasis–related complications.

FSH Levels Are Related to E-cadherin Expression and Subcellular Location in Nonfunctioning Pituitary Tumors

CONTEXT

Gonadotroph pituitary neuroendocrine tumors (PitNETs) can express follicle-stimulating hormone (FSH) and luteinizing hormone (LH) or be hormone negative, but they rarely secrete hormones. During tumor development, epithelial cells develop a mesenchymal phenotype. This process is characterized by decreased membranous E-cadherin and translocation of E-cadherin to the nucleus. Estrogen receptors (ERs) regulate both E-cadherin and FSH expression and secretion. Whether the hormone status of patients with gonadotroph PitNETs is regulated by epithelial-to-mesenchymal transition (EMT) and ERs is unknown.

OBJECTIVES

To study the effect of EMT on hormone expression in gonadotroph nonfunctioning (NF)-PitNETs.

DESIGN

Molecular and clinical analyses of 105 gonadotroph PitNETs. Immunohistochemical studies and real-time quantitative polymerase chain reaction were performed for FSH, LH, E-cadherin, and ERα. Further analyses included blood samples, clinical data, and radiological images.

SETTING

All patients were operated on in the same tertiary referral center.

RESULTS

NF-PitNET with high FSH expression had decreased immunohistochemical staining for membranous E-cadherin (P < .0001) and increased staining for nuclear E-cadherin (P < .0001). Furthermore, high FSH expression was associated with increased ERα staining (P = .0002) and ERα mRNA (P = .0039). Circulating levels of plasma-FSH (P-FSH) correlated with FSH staining in gonadotroph NF-PitNET (P = .0025). Tumor size and invasiveness was not related to FSH staining, E-cadherin, or ERα. LH expression was not associated with E-cadherin or ERα.

CONCLUSION

In gonadotroph PitNETs, FSH staining is related to E-cadherin, ERα expression, and circulating levels of P-FSH. There was no association between FSH staining and invasiveness. The clinical significance of these findings will be investigated in ongoing prospective studies.

SNAIL expression correlates with the translocation of syndecan‑1 intracellular domain into the nucleus in prostate cancer cell lines

Zinc finger protein SNAI1 (SNAIL) and zinc finger protein SNAI2 (SLUG) transcription factors promote epithelial-mesenchymal transition, a process through which epithelial cells acquire a mesenchymal phenotype, increasing their migratory and invasive properties. In prostate cancer (PCa) progression, increased expression levels of SNAIL and SLUG have been described. In advanced PCa, a decrease in the cell surface proteoglycan syndecan-1 (SDC-1), which has a role in cell-to-extracellular matrix adhesion, has been observed. Notably, SDC-1 nuclear location has been observed in mesenchymal cancers. The present study aimed to determine if SNAIL and SLUG may be associated with the nuclear location of SDC-1 in PCa. To determine the location of SDC-1, antibodies against its intracellular domain (ID) or extracellular domain (ED) were used in benign prostatic hyperplasia (BPH) and PCa samples with high Gleason scores. Only ID-SDC-1 was located in the cell nuclei in advanced PCa samples, but not in the BPH samples. ED-SDC-1 was located in the cell membrane and cytoplasm, exhibiting decreased levels in PCa in comparison with those in BPH. Furthermore, LNCaP and PC3 PCa cell lines with ectopic SNAIL expression exhibited nuclear ID-SDC-1. No change was observed in the ED-SDC-1 levels, and maintained its location in the cell membrane and cytoplasm. SLUG induced no change in ID-SDC-1 location. At the protein level, an association between SNAIL and nuclear ID-SDC-1 was observed. In conclusion, the results of the present study demonstrated that nuclear ID-SDC-1 localization was associated with SNAIL expression in PCa cell lines.

The Syk Kinase Promotes Mammary Epithelial Integrity and Inhibits Breast Cancer Invasion by Stabilizing the E-Cadherin/Catenin Complex

While first discovered in immunoreceptor signaling, the Syk protein kinase behaves as a tumor and metastasis suppressor in epithelial cells. Its reduced expression in breast and other carcinomas is correlated with decreased survival and increased metastasis risk, but its action mechanism remains largely unknown. Using phosphoproteomics we found that Syk phosphorylated E-cadherin and α-, β-, and p120-catenins on multiple tyrosine residues that concentrate at intercellular junctions. Increased Syk expression and activation enhanced E-cadherin/catenin phosphorylation, promoting their association and complex stability. In human breast cancer cells, Syk stimulated intercellular aggregation, E-cadherin recruitment and retention at adherens junctions, and promoted epithelial integrity, whereas it inhibited cell migration and invasion. Opposite effects were obtained with Syk knockdown or non-phosphorylatable mutant E-cadherin expression. Mechanistically, Syk stimulated the interaction of the E-cadherin/catenin complex with zonula occludens proteins and the actin cytoskeleton. Conditional Syk knockout in the lactating mouse mammary gland perturbed alveologenesis and disrupted E-cadherin localization at adherens junctions, corroborating the observations in cells. Hence, Syk is involved in the maintenance of the epithelial integrity of the mammary gland via the phosphorylation and stabilization of the E-cadherin/catenin adherens junction complex, thereby inhibiting cell migration and malignant tumor invasion.

KLF4, A Gene Regulating Prostate Stem Cell Homeostasis, Is a Barrier to Malignant Progression and Predictor of Good Prognosis in Prostate Cancer

There is a considerable need to identify those individuals with prostate cancer who have indolent disease. We propose that genes that control adult stem cell homeostasis in organs with slow turnover, such as the prostate, control cancer fate. One such gene, KLF4, overexpressed in murine prostate stem cells, regulates their homeostasis, blocks malignant transformation, and controls the self-renewal of tumor-initiating cells. KLF4 loss induces the molecular features of aggressive cancer and converts PIN lesions to invasive sarcomatoid carcinomas; its re-expression in vivo reverses this process. Bioinformatic analysis links these changes to human cancer. KLF4 and its downstream targets make up a gene signature that identifies indolent tumors and predicts recurrence-free survival. This approach may improve prognosis and identify therapeutic targets for advanced cancer.

Available criteria for segregating prostate cancer patients into those requiring therapeutic intervention and those who can be followed are inadequate. Xiong et al. show that KLF4 and its downstream targets make up a gene signature that identifies indolent tumors. This approach may improve prognosis and identify therapeutic targets for advanced cancer.

E-cadherin clone 36 nuclear staining dictates adverse disease outcome in lobular breast cancer patients

Breast cancer is a heterogeneous disease and additional biomarkers for individually predicting patient outcomes are needed. Aberrant membrane E-cadherin immunoexpression has been demonstrated in lobular breast cancer. Also, E-cadherin nuclear staining has been reported, associating with prognosis in various tumors. Here, we explore whether membrane or nuclear staining of E-cadherin has the potential to dictate prognosis of patients with lobular breast cancer. We selected a cohort of 285 consecutively diagnosed lobular breast cancer patients and performed immunohistochemistry for E-cadherin (clones 36, EP700Y, and NCH38) and P-cadherin (clone 56C1) in representative formalin-fixed paraffin-embedded blocks. All patients were female, HER2-negative and surgically treated in a single institution. Survival curves were computed by Kaplan-Meier analysis. Hazard ratios and respective 95% confidence intervals were estimated using Cox regression models. Statistical significance was set at p < 0.05. Nuclear staining for E-cadherin clone 36 was frequent (35%), contrarily to other antibodies tested. Negative correlation was found between nuclear and membrane E-cadherin clone 36 immunostaining (r_s = -0.30, p < 0.001), whereas positive correlation was found between membrane immunoexpression of E-cadherin clone 36 and P-cadherin (r_s = 0.31, p < 0.001). Patients with any evidence of E-cadherin clone 36 nuclear immunostaining disclosed significantly worse overall survival, disease-specific-survival and disease/progression-free survival (hazard ratio = 2.059, 95% confidence interval 1.313-3.230; hazard ratio = 1.980, 95% confidence interval 1.121-3.495; and hazard ratio = 2.341, 95% confidence interval 1.403-3.905, respectively). Differences in survival were more remarkable when considering nuclear E-cadherin immunoexpression in ≥50% tumor cells. Poorer survival was maintained in multivariable analysis, after adjusting for age, menopausal and PR status, treatment course, vascular invasion, tumor grade and stage. Our results support the use of antibodies against the cytoplasmic domain of E-cadherin, such as clone 36, which may reveal nuclear immunostaining and indicate more aggressive clinical course in patients with lobular breast cancer. We hypothesize that E-cadherin is cleaved and translocated to nucleus functioning as transcription factor.

Nuclear E-Cadherin Acetylation Promotes Colorectal Tumorigenesis via Enhancing β-Catenin Activity

The E-cadherin/β-catenin signaling pathway plays a critical role in the maintenance of epithelial architecture and regulation of tumor progression. Normally, E-cadherin locates on the cell surface with its cytosolic domain linking to the actin cytoskeleton through interaction with catenins. Although the nuclear localization of E-cadherin has been frequently observed in various types of cancers, little is known regarding the functional consequences of its nuclear translocation. Here, we showed that in colorectal cancer samples and cell lines, E-cadherin localized in the nucleus; and the nuclear localization was mediated through protein interaction with CTNND1. In the nucleus, E-cadherin was acetylated by CREB-binding protein at Lysine⁸⁷⁰ and Lysine⁸⁷¹ in its β-catenin-binding domain, and the acetylation can be reversed by SIRT2. Acetylation of nuclear E-cadherin attenuated its interaction with β-catenin, which therefore released β-catenin from the complex, resulting in increased expression of its downstream genes and accelerated tumor growth and migration. Further study showed that acetylation level of nuclear E-cadherin had high prognostic significance in clinical colorectal samples. Taken together, our findings reveal a novel mechanism of tumor progression through posttranslational modification of E-cadherin, which may serve as a potential drug target of tumor therapy. IMPLICATIONS: This finding that acetylation of nuclear E-cadherin regulates β-catenin activity expands our understanding of the acetylation of E-cadherin promotes colorectal cancer cell growth and suggests novel therapeutic approaches of targeting acetylation in tumors.

Upregulation of the BDNF/TrKB pathway promotes epithelial-mesenchymal transition, as well as the migration and invasion of cervical cancer

Brain-derived neurotrophic factor (BDNF) has previously been demonstrated to be associated with several types of cancer. In addition, its receptor, tropomyosin related kinase B (TrkB) is involved in tumor invasion and metastasis. Epithelial-mesenchymal transition (EMT) is associated with metastasis in cancers. Thus, The aim of the present study was to examine whether BDNF/TrKB expression is linked to a poor survival and the acquisition of the EMT phenotype in cervical cancer. We found that a high positive expression of BDNF/TrKB was associated with poor survival in cervical cancer. Our results revealed that high expression levels of BDNF/TrKB were observed in cervical cancer compared to normal cells. Importantly, we demonstrated that the silencing of TrKB suppressed the activation of EMT via the downregulation of N-cadherin, vimentin, matrix metalloproteinase (MMP)2 and MMP9, and the upregulation of E-cadherin and tissue inhibitor of metalloproteinases (TIMP)2, which resulted in suppressed cell proliferation, migration and invasion. Furthermore, high phosphorylation levels of ERK and Akt were observed in the cervical cancer cells, while these levels were decreased in the cells in which TrKB was knocked down. On the whole, these findings suggest that the BDNF/TrKB pathway is a promising target for the prevention of tumor proliferation, invasion, metastasis and EMT in cervical cancer cells.

Role of microRNAs in endocrine cancer metastasis

The deregulation of transcription and processing of microRNAs (miRNAs), as well as their function, has been involved in the pathogenesis of several human diseases, including cancer. Despite advances in therapeutic approaches, cancer still represents one of the major health problems worldwide. Cancer metastasis is an aggravating factor in tumor progression, related to increased treatment complexity and a worse prognosis. After more than one decade of extensive studies of miRNAs, the fundamental role of these molecules in cancer progression and metastasis is beginning to be elucidated. Recent evidences have demonstrated a significant role of miRNAs on the metastatic cascade, acting either as pro-metastatic or anti-metastatic. They are involved in distinct steps of metastasis including epithelial-to-mesenchymal transition, migration/invasion, anoikis survival, and distant organ colonization. Studies on the roles of miRNAs in cancer have focused mainly on two fronts: the establishment of a miRNA signature for different tumors, which may aid in early diagnosis using these miRNAs as markers, and functional studies of specific miRNAs, determining their targets, function and regulation. Functional miRNA studies on endocrine cancers are still scarce and represent an important area of research, since some tumors, although not frequent, present a high mortality rate. Among the endocrine tumors, thyroid cancer is the most common and best studied. Several miRNAs show lowered expression in endocrine cancers (i.e. miR-200s, miR-126, miR-7, miR-29a, miR-30a, miR-137, miR-206, miR-101, miR-613, miR-539, miR-205, miR-9, miR-195), while others are commonly overexpressed (i.e. miR-21, miR-183, miR-31, miR-let7b, miR-584, miR-146b, miR-221, miR-222, miR-25, miR-595). Additionally, some miRNAs were found in serum exosomes (miR-151, miR-145, miR-31), potentially serving as diagnostic tools. In this review, we summarize studies concerning the discovery and functions of miRNAs and their regulatory roles in endocrine cancer metastasis, which may contribute for the finding of novel therapeutic targets. The review focus on miRNAs with at least some identified targets, with established functions and, if possible, upstream regulation.

Nuclear localization of tricellulin promotes the oncogenic property of pancreatic cancer

Accumulating evidence has shown that dysregulation of tight junctions (TJs) is involved in tumor development and progression. In this study, we investigated the expression and subcellular distribution of tricellulin, which constitutes tricellular TJs, using human pancreatic adenocarcinomas. In well-differentiated pancreatic adenocarcinoma tissues, tricellulin immunostaining was prominent in the cytoplasm and the plasma membrane. In contrast, in poorly differentiated tissues, its immunostaining was predominantly observed in the nuclei and was almost absent in the plasma membrane. The distinct immunostaining of tricellulin successfully distinguished poorly differentiated adenocarcinoma from moderately and well-differentiated adenocarcinomas with high levels of sensitivity and specificity. Nuclear tricellulin expression significantly correlated with lymph node metastasis, lymphatic invasion and poor survival. In pancreatic cancer cell lines, tricellulin localization shifted from the membrane to nucleus with decreasing differentiation status. Nuclear localization of tricellulin promoted cell proliferation and invasiveness possibly in association with MAPK and PKC pathways in pancreatic cancers. Our results provide new insights into the function of tricellulin, and its nuclear localization may become a new prognostic factor for pancreatic cancers.

Ki-67 prognostic and therapeutic decision driven marker for pancreatic neuroendocrine neoplasms (PNENs): A systematic review

BACKGROUND

We systematically evaluate the current evidence regarding Ki-67 as a prognostic factor in pancreatic neuroendocrine neoplasms to evaluate the differences of this marker in primary tumors and in distant metastases as well as the values of Ki-67 obtained by fine needle aspiration and by histology.

METHODS

The literature search was carried out using the MEDLINE/PubMed database, and only papers published in the last 10 years were selected.

RESULTS

The pancreatic tissue suitable for Ki-67 evaluation was obtained from surgical specimens in the majority of the studies. There was a concordance of 83% between preoperative and postoperative Ki-67 evaluation. Pooling the data of the studies which compared the Ki-67 values obtained in both cytological and surgical specimens, we found that they were not related. The assessment of Ki-67 was manual in the majority of the papers considered for this review. In order to eliminate manual counting, several imaging methods have been developed but none of them are routinely used at present. Twenty-two studies also explored the role of Ki-67 utilized as a prognostic marker for pancreatic neuroendocrine neoplasms and the majority of them showed that Ki-67 is a good prognostic marker of disease progression. Three studies explored the Ki-67 value in metastatic sites and one study demonstrated that, in metachronous and synchronous liver metastases, there was no significant variation in the index of proliferation.

CONCLUSIONS

Ki-67 is a reliable prognostic marker for pancreatic neuroendocrine neoplasms.

Identification of potential biomarkers to differentially diagnose solid pseudopapillary tumors and pancreatic malignancies via a gene regulatory network

Background

Solid pseudopapillary neoplasms (SPN) are pancreatic tumors with low malignant potential and good prognosis. However, differential diagnosis between SPN and pancreatic malignancies including pancreatic neuroendocrine tumor (PanNET) and ductal adenocarcinoma (PDAC) is difficult. This study tried to identify candidate biomarkers for the distinction between SPN and the two malignant pancreatic tumors by examining the gene regulatory network of SPN.

Methods

The gene regulatory network for SPN was constructed by a co-expression model. Genes that have been reported to be correlated with SPN were used as the clues to hunt more SPN-related genes in the network according to a shortest path approach. By means of the K-nearest neighbor algorithm (KNN) classifier evaluated by the jackknife test, sets of genes to distinguish SPN and malignant pancreatic tumors were determined.

Results

We took a new strategy to identify candidate biomarkers for differentiating SPN from the two malignant pancreatic tumors PanNET and PDAC by analyzing shortest paths among SPN-related genes in the gene regulatory network. 43 new SPN-relevant genes were discovered, among which, we found hsa-miR-194 and hsa-miR-7 along with 7 transcription factors (TFs) such as SOX11, SMAD3 and SOX4 etc. could correctly differentiate SPN from PanNET, while hsa-miR-204 and 4 TFs such as SOX9, TCF7 and PPARD etc. were demonstrated as the potential markers for SPN versus PDAC. 14 genes were demonstrated to serve as the candidate biomarkers for distinguishing SPN from PanNET and PDAC when considering them as malignant pancreatic tumors together.

Conclusion

This study provides new candidate genes related to SPN and the potential biomarkers to differentiate SPN from PanNET and PDAC, which may help to diagnose patients with SPN in clinical setting. Furthermore, candidate biomarkers such as SOX11 and hsa-miR-204 which could cause cell proliferation but inhibit invasion or metastasis may be of importance in understanding the molecular mechanism of pancreatic oncogenesis and could be possible therapeutic targets for malignant pancreatic tumors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0718-3) contains supplementary material, which is available to authorized users.

Moonlighting proteins in cancer

Since the 1980s, growing evidence suggested that the cellular localization of proteins determined their activity and biological functions. In a classical view, a protein is characterized by the single cellular compartment where it primarily resides and functions. It is now believed that when proteins appear in different subcellular locations, the cells surpass the expected activity of proteins given the same genomic information to fulfill complex biological behavior. Many proteins are recognized for having the potential to exist in multiple locations in cells. Dysregulation of translocation may cause cancer or contribute to poorer cancer prognosis. Thus, quantitative and comprehensive assessment of dynamic proteins and associated protein movements could be a promising indicator in determining cancer prognosis and efficiency of cancer treatment and therapy. This review will summarize these so-called moonlighting proteins, in terms of a coupled intracellular cancer signaling pathway. Determination of the detailed biological intracellular and extracellular transit and regulatory activity of moonlighting proteins permits a better understanding of cancer and identification of potential means of molecular intervention.

E-cadherin expression in obesity-associated, Kras-initiated pancreatic ductal adenocarcinoma in mice

BACKGROUND

The epithelial-mesenchymal transition (EMT) is critical in the development of invasive epithelial malignancies. EMT is accelerated by inflammation and results in decreased E-cadherin expression. Diet-induced obesity is an inflammatory state that accelerates pancreatic carcinogenesis; its effect on EMT and E-cadherin expression in the development of pancreatic ductal adenocarcinoma is unclear.

METHODS

Conditional Kras(G12D) mice were fed a control diet or a high-fat, high-calorie diet for 3 or 9 months (n = 10 each). Immunohistochemistry with anti-E-cadherin antibody was performed. E-cadherin expression was characterized by staining intensity, location, and proportion of positive cells. In vitro expression of E-cadherin and Slug in primary pancreatic intraepithelial neoplasia (PanIN) and cancer cells was determined by Western blot.

RESULTS

The HFCD led to increased weight gain in both 3- (15.8 vs 5.6 g, P < .001) and 9-month (19.8 vs 12.9 g, P = .007) mice. No differences in E-cadherin expression among various stages of preinvasive PanIN lesions were found--regardless of age or diet. In invasive cancer, E-cadherin expression was aberrant, with loss of membranous staining and prominent cytoplasmic staining, associated with strong, cytoplasmic expression of β-catenin. In vitro expression of E-cadherin was greatest in primary PanIN cells, accompanied by absent Slug expression. Cancer cell lines demonstrated significantly decreased E-cadherin expression in the presence of upregulated Slug.

CONCLUSION

Despite increased pancreatic inflammation and accelerated carcinogenesis, the high-fat, high-calorie diet did not induce changes in E-cadherin expression in PanIN lesions of all stages. Invasive lesions demonstrated aberrant cytoplasmic E-cadherin staining. Loss of normal membranous localization may reflect a functional loss of E-cadherin.

Monitoring interactions and dynamics of endogenous beta-catenin with intracellular nanobodies in living cells

β-catenin is the key component of the canonical Wnt pathway and plays a crucial role in a multitude of developmental and homeostatic processes. The different tasks of β-catenin are orchestrated by its subcellular localization and participation in multiprotein complexes. To gain a better understanding of β-catenin's role in living cells we have generated a new set of single domain antibodies, referred to as nanobodies, derived from heavy chain antibodies of camelids. We selected nanobodies recognizing the N-terminal, core or C-terminal domain of β-catenin and applied these new high-affinity binders as capture molecules in sandwich immunoassays and co-immunoprecipitations of endogenous β-catenin complexes. In addition, we engineered intracellularly functional anti-β-catenin chromobodies by combining the binding moieties of the nanobodies with fluorescent proteins. For the first time, we were able to visualize the subcellular localization and nuclear translocation of endogenous β-catenin in living cells using these chromobodies. Moreover, the chromobody signal allowed us to trace the accumulation of diffusible, hypo-phosphorylated β-catenin in response to compound treatment in real time using High Content Imaging. The anti-β-catenin nanobodies and chromobodies characterized in this study are versatile tools that enable a novel and unique approach to monitor the dynamics of subcellular β-catenin in biochemical and cell biological assays.

Statin-induced mevalonate pathway inhibition attenuates the growth of mesenchymal-like cancer cells that lack functional E-cadherin mediated cell cohesion

The cholesterol reducing drugs, statins, exhibit anti-tumor effects against cancer stem cells and various cancer cell lines, exert potent additivity or synergy with existing chemotherapeutics in animal models of cancer and may reduce cancer incidence and cancer related mortality in humans. However, not all tumor cell lines are sensitive to statins, and clinical trials have demonstrated mixed outcomes regarding statins as anticancer agents. Here, we show that statin-induced reduction in intracellular cholesterol levels correlate with the growth inhibition of cancer cell lines upon statin treatment. Moreover, statin sensitivity segregates with abundant cytosolic vimentin expression and absent cell surface E-cadherin expression, a pattern characteristic of mesenchymal-like cells. Exogenous expression of cell surface E-cadherin converts statin- sensitive cells to a partially resistant state implying that statin resistance is in part dependent on the tumor cells attaining an epithelial phenotype. As metastasizing tumor cells undergo epithelial to mesenchymal transition during the initiation of the metastatic cascade, statin therapy may represent an effective approach to targeting the cells most likely to disseminate.

Merkel cell carcinoma - recent advances in the biology, diagnostics and treatment

Merkel cell carcinoma (MCC) is an uncommon primary cutaneous carcinoma with neuroendocrine differentiation. Since recent discovery of MCCs strong association with Merkel cell polyomavirus (MCPyV), there has been a rapid increase in the understanding of the carcinomas genetics, molecular biology and pathogenesis. In our study, we reviewed recent advances and controversies concerning MCC histogenesis, epidemiology, diagnostic and prognostic markers. We analyzed the association of MCPyV with MCC and the possible new targets for therapy. We also examined English-based literature regarding MCC pathogenesis published between 2008 and 2013, which lead to a deeper understanding of the topic. Our study showed that the association of MCPyV strongly influences the course of MCC. Additionally, it has been shown that a immunological response to MCPyV may in the future give hope to identify new therapeutic strategies in treatment of this fatal malignancy. This article is part of a Directed Issue entitled: Rare Cancers.

α-Methylacyl-CoA racemase (P504S) is a useful marker for the differential diagnosis of solid pseudopapillary neoplasm of the pancreas

The differential diagnosis of solid pseudopapillary neoplasm (SPN) from some other nonductal pancreatic tumors may be difficult because of similarities in morphological features. Therefore, immunohistochemical staining is frequently necessary. α-Methylacyl-CoA racemase (AMACR) is a diagnostically useful marker for prostatic cancer and papillary renal cell carcinoma. The aim of this study was to investigate AMACR as a new immunohistochemical marker to differentiate SPNs from other nonductal pancreatic tumors. We investigated immunohistochemical staining for AMACR in 26 SPNs, 21 pancreatic neuroendocrine tumors, and 7 acinar cell carcinomas. All cases of SPN showed granular cytoplasmic expression of AMACR, whereas all cases of pancreatic neuroendocrine tumors and acinar cell carcinomas were negative for this immunohistochemical marker. Hence, our findings demonstrate for the first time that AMACR is a useful immunohistochemical marker for the differential diagnosis of SPNs.

Diagnostic role of immunohistochemistry in the evaluation of breast pathology specimens

CONTEXT

Immunohistochemistry plays a vital role in the evaluation of breast pathology specimens.

OBJECTIVE

To discuss the role of myoepithelial cell markers in the evaluation of various breast lesions. Other markers, such as E-cadherin and those used to differentiate mammary carcinoma from metastatic tumors to the breast, and markers used in the differential diagnosis of Paget disease, are also discussed.

DATA SOURCES

Data were obtained from review of the pertinent peer-reviewed literature.

CONCLUSIONS

Myoepithelial cell markers vary in their sensitivity and specificity, and one should be aware of the potential pitfalls in interpretation. Using panels of 2 or more myoepithelial cell markers is always recommended, either singly or in cocktail forms. Although negative E-cadherin staining supports the diagnosis of lobular origin, positive staining does not rule it out. Immunohistochemistry can be helpful in differentiating Paget disease from its mimics. Although metastatic tumors to the breast are rare, a triple-negative immunophenotype and absence of an in situ component should be a "red flag" for such possibility, especially in patients with clinical history of an extramammary malignancy.

Primary bladder adenocarcinoma versus metastatic colorectal adenocarcinoma: a persisting diagnostic challenge

Aim

This study attempted to distinguish primary bladder adenocarcinoma (PBA) from metastatic colonic adenocarcinomas (MCA), which is a difficult diagnostic and clinical problem.

Methods

Twenty-four cases of bladder adenocarcinomas (12 primary & 12 metastatic colorectal) were included in the study with urothelial carcinoma (UC) and colonic adenocarcinoma (CA) as controls. A panel of immunohistochemical (IHC) stains along with fluorescence in-situ hybridization (FISH), using the UroVysion probe set, was performed.

Results

The majority of the PBAs presented with advanced disease. Enteric histologic subtype was the most common morphological variant. Strong nuclear with cytoplasmic-membranous staining of β-catenin was seen in 75% of MCA and only 16.7% PBA (<10% staining cells). Although abnormal nuclear staining with E-cadherin was seen in both PBA and MCA, it was more frequent in former. CK-7, CK-20, villin and CDX-2 stains were not helpful in distinguishing the two entities. FISH did not reveal any unique differences in chromosomal abnormality between the two groups.

Conclusion

Although there was a statistically significant difference in β-catenin and E-cadherin staining between two groups, we did not find any IHC or FISH marker that was specific for PBA. Distinction between PBA and MCA remains a diagnostic problem and clinical correlation is vital before rendering a diagnosis.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1393156268152357

Molecular pathology and genetics of pancreatic endocrine tumours

Pancreatic neuroendocrine tumours (PETs) are the second most frequent pancreatic neoplasms. Their poor chemosensitivity, high rate of metastatic disease and relatively long survival make PETs an ideal field to be explored for novel therapies based on specific molecular changes. PETs are generally sporadic but can also arise within hereditary syndromes, such as multiple endocrine neoplasia type 1, von Hippel-Lindau, neurofibromatosis type 1 and tuberous sclerosis complex, which represent a model for sporadic cases too. Among allelic imbalances, main genomic changes involve gain of 17q, 7q and 20q and loss of 11q, 6q and 11p, which identify regions of putative candidate oncogenes or tumour suppressor genes (TSGs), respectively, sometime with potential prognostic significance. Overexpression of Src-like kinases and cyclin D1 (CCND1) oncogene has been described. As for TSGs, P53 (TP53), DPC4/SMAD4 and RB (RB1) are not implicated in PET tumorigenesis, while for p16INK4a (CDKN2A), TIMP3, RASSF1A and hMLH1, more data are available, suggesting a role for methylation as a silencing mechanism. In the last decade, gene expression profile studies, analysis of microRNAs and, more recently, large-scale mutational analysis have highlighted commonly altered molecular pathways in the pathology of PETs. The roles of the mammalian target of rapamycin pathway, and its connection with Src kinases, and the activity of a number of tyrosine kinase receptors seem to be pivotal, as confirmed by the results of recent clinical trials with targeted agents. Mutations of DAXX and ATRX are common and related to altered telomeres but not to prognosis.

E-cadherin in canine mast cell tumors: decreased expression and altered subcellular localization in Grade 3 tumors

Mast cell tumors (MCTs) are the most frequent round cell tumors in dogs and comprise approximately 21% of all canine cutaneous tumors. MCTs are highly invasive and metastatic corresponding to the histological grade. E-cadherin is an adhesion molecule expressed in epithelial cells and although it is an epithelial cellular marker, studies have shown expression of E-cadherin in canine round cell tumors. To better characterize the expression pattern of E-cadherin in several different histological grades of MCTs in dogs, the expression and localization of the adhesion molecule was investigated using immunohistochemistry. For this purpose, 18 cutaneous MCTs were classified into three histological grades, 1, 2 or 3. Clinical history and follow-up data were available for all of the dogs. Cytoplasmic and nuclear expressions of E-cadherin in all three types of tumors were verified by immunostaining using two different antibodies. There was decreased E-cadherin expression in the more aggressive MCTs (Grade 3), suggesting an association between E-cadherin and tumor aggressiveness. Additionally, the loss of E-cadherin expression in either the cytoplasm or nucleus in more aggressive and undifferentiated tumor types confirmed the importance of cellular adhesion in tumor behavior.

Immunohistochemical evaluation of solid pseudopapillary tumors of the pancreas: the expression pattern of CD99 is highly unique

The aim of this study was to investigate CD99 as a new marker to characterize solid pseudopapillary tumors (SPTs), and to determine a specific panel of markers to identify the disease. We analyzed the clinicopathological characteristics and immunohistochemical features of 37 patients with SPT. All 37 tumors displayed intracytoplasmic dot-like immunoreactivity of CD99 in contrast to membranous staining in all pancreatic endocrine tumors and most of acinar cell carcinomas, along with negative immunostaining in ductal carcinomas. In addition, we observed a loss of expression of E-cadherin in all SPTs as well as in some other pancreatic tumors, and aberrant nuclear expression of β-catenin in most SPTs. Our findings demonstrated for the first time that the pattern of CD99 expression was highly specific for distinguishing SPTs from other pancreatic tumors. CD99 combined with E-cadherin/β-catenin and CD10 can be used as a relatively specific expression profile of SPTs.

Current surgical management of pancreatic endocrine tumor liver metastases

BACKGROUND

The management of metastatic disease in pancreatic endocrine tumors (PETs) demands a multidisciplinary approach and the cooperation of several medical specialties. The role of surgery is critical, even when a radical excision cannot always be achieved.

DATA SOURCES

A PubMed search of relevant articles published up to February 2011 was performed to identify current information about PET liver metastases regarding diagnosis and management, with an emphasis on surgery.

RESULTS

The early diagnosis of metastases and their accurate localization, most commonly in the liver, is very important. Surgical options include radical excision, and palliative excision to relieve symptoms in case of failure of medical treatment. The goal of the radical excision is to remove the primary tumor bulk and all liver metastases at the same time, but unfortunately it is not feasible in most cases. Palliative excisions include aggressive tumor debulking surgeries in well-differentiated carcinomas, trying to remove at least 90% of the tumor mass, combined with other additional destructive techniques such as hepatic artery embolization or chemoembolization to treat metastases or chemoembolization to relieve symptoms in cases of rapidly growing tumors. The combination of chemoembolization and systemic chemotherapy results in better response and survival rates. Other local destructive techniques include ethanol injection, cryotherapy and radiofrequency ablation.

CONCLUSION

It seems that the current management of PETs can achieve important improvements, even in advanced cases.

Pancreatic endocrine tumors

The endocrine cells of the pancreas and their related cells throughout the gastrointestinal tract give rise to a variety of tumors that pose a diagnostic challenge. There has been progress in understanding their histogenesis, morphology, immunohistochemistry, molecular biology and classifications. This review will focus on nomenclature/terminology, classification, the role of immunohistochemistry, molecular advances, including genetic predisposition, and potential therapeutic targets to define the role of pathology in the application of prognostic and predictive markers for this disease.

Immunohistochemical Expression of E-cadherin Does Not Distinguish Canine Cutaneous Histiocytoma From Other Canine Round Cell Tumors

Immunohistochemistry for E-cadherin (ECAD) has been used to distinguish canine cutaneous histiocytoma from other leukocytic neoplasms (“round cell tumors”). To determine the specificity of this test, 5 types of canine cutaneous round cell tumors were evaluated for immunohistochemical expression of ECAD. Tumors of all 5 types had variable cytoplasmic, plasma membrane, and/or paranuclear ECAD expression: All 13 cutaneous histiocytomas were ECAD+; all but 1 of 14 mast cell tumors expressed ECAD; 10 of 12 epitheliotropic lymphomas reacted with E-cadherin antibody; of 72 plasmacytomas, 54 were ECAD+; and 5 of 5 histiocytic sarcomas were positive. Conclusions based on these results include the following: First, immunoreactivity for ECAD is not limited to leukocytes of cutaneous histiocytoma; second, antibody to ECAD also labels neoplastic cells in most mast cell tumors, plasmacytomas, cutaneous histiocytic sarcomas, and epitheliotropic lymphomas; third, although most histiocytomas have membranous ECAD expression, the immunoreactivity varies among round cell tumors and is frequently concurrent in different cellular compartments; fourth, the distinctively paranuclear ECAD expression pattern in epitheliotropic lymphomas might distinguish them from other round cell tumors; and, fifth, ECAD should be used with other markers (eg, MUM1 for plasmacytomas, KIT for mast cell tumors, CD3 and CD79a for lymphomas) to distinguish among canine round cell tumors.

Clinical and immunohistochemical features of 34 solid pseudopapillary tumors of the pancreas

BACKGROUND AND AIM

Clinicopathological data regarding pancreatic solid pseudopapillary tumors (SPT) in a multiethnic country are limited. The aim of the present study was to characterize pancreatic SPT in Australia.

METHODS

Clinicopathological features, treatment, immunohistochemical findings and outcome data of 34 patients (79% Caucasian, 12% Asian, 6% South Pacific Islander and 3% African) with pancreatic SPT were reviewed.

RESULTS

The most presenting complaint was abdominal pain. Median diameter of tumors was 60 mm (range: 20-220); predominantly located in the pancreatic tail (tail : body : head = 23:3:8). All tumors were resected and patients underwent surgery, including a liver resection for metastasis, all patients were alive after a median follow up of 70 months (IQR: 48-178). Two patients underwent repeated surgery for local recurrences with liver metastases after 8 and 18 months, which were successfully managed by surgical resection. Completeness of excision, perineural spread, vascular space invasion, mitotic rate and cellular atypia did not predict recurrence. In all cases, there was aberrant nuclear staining of beta-catenin and a loss of membranous expression of E-cadherin with aberrant nuclear localization of the cytoplasmic domain. Most pancreatic SPT were also strongly positive for CD10 (96%), progesterone receptor (79%), cytokeratin (28%), synapthophysin (26%) and chromogranin (15%).

CONCLUSIONS

Pancreatic SPT occur in all races and are uniformly indolent. Given complete resection of a pancreatic SPT is usually curative and recurrences can be treated with re-operation, correct diagnosis is important.

ILK expression in human basal cell carcinoma correlates with epithelial-mesenchymal transition markers and tumour invasion

AIMS

Epithelial-mesenchymal transition (EMT) has been known to play a significant role in tumour progression. Integrin-linked kinase (ILK) has been recently added to the growing list of EMT regulators that control some aspect of carcinogenesis. The aim was to study ILK expression and its relevance to EMT markers in human basal cell carcinoma (BCC).

METHODS AND RESULTS

Paraffin-embedded tissue sections from 100 human BCC cases were processed by immunohistochemistry for the expression of ILK, E-cadherin, Snail, beta-catenin and alpha-smooth muscle actin (alpha-SMA). ILK overexpression was observed in 100% of cases and strongly correlated with tumour invasion and infiltrative BCC. Loss of membranous E-cadherin was found in 71% of cases while nuclear immunoreactivity for E-cadherin was also observed in 90% of the tumours. Snail, nuclear beta-catenin and alpha-SMA expression was detected in 100%, 99% and 97% of tumours, respectively. Aberrant expression of E-cadherin, nuclear beta-catenin and alpha-SMA correlated with BCC tumour invasion. Interestingly, there was a significant correlation between ILK expression and all the EMT markers examined.

CONCLUSIONS

ILK overexpression in BCC is implicated in tumour progression probably through the induction of an EMT-related molecular profile. Nuclear localization of E-cadherin in BCC is also associated with aggressive tumour features.

The expression of E-cadherin in somatotroph pituitary adenomas is related to tumor size, invasiveness, and somatostatin analog response

CONTEXT

Appropriate cell-to-cell adhesion is fundamental for the epithelial phenotype of pituitary cells. Loss of the adhesion protein E-cadherin has been associated with invasiveness, metastasis, and poor prognosis in cancers of epithelial origin. In somatotroph adenomas, a variable and reduced expression of E-cadherin has been demonstrated. In addition, nuclear translocation of E-cadherin was found to correlate with pituitary tumor invasion.

OBJECTIVE

The objective was to examine the protein expression of E-cadherin in somatotroph pituitary adenomas in relation to adenoma size, invasiveness, and somatostatin analog (SMS) efficacy.

PATIENTS AND METHODS

Eighty-three patients were included, and 29 were treated preoperatively with SMS. Adenoma E-cadherin protein expression was analyzed by Western blot (61 patients) and immunohistochemistry (IHC) (80 patients) with antibodies directed against both extracellular and intracellular domains (IHC). The acute (direct surgery group) and long-term (preoperatively treated group) SMS responses were evaluated. Baseline tumor volume and invasiveness were measured on magnetic resonance imaging scans.

RESULTS

Membranous E-cadherin was lost in several adenomas. Nine of these were nuclear E-cadherin positive. The E-cadherin protein expression correlated negatively to tumor size and positively to acute SMS response. Low E-cadherin levels (preoperatively treated group only) and loss of membranous E-cadherin correlated to tumor invasiveness. The E-cadherin level correlated positively to tumor reduction after SMS treatment, and adenomas with nuclear E-cadherin staining had lower IGF-I reduction and tumor shrinkage. Preoperatively treated adenomas had reduced E-cadherin protein levels, but the IHC expression was unaltered.

CONCLUSION

Reduced E-cadherin expression may correlate to a dedifferentiated phenotype in the somatotroph pituitary adenomas.

Beta-catenin expression in uterine sarcomas and its relation to clinicopathological parameters

Aberrations in the Wnt/beta-catenin signalling pathway are suggested as mediators of chromosomal instability and carcinogenesis. beta-catenin acts both as a component of the membranous adhesion system, and as a transcription activator in the nucleus. beta-Catenin immunoreactivity was evaluated in 353 uterine sarcomas (US) including 231 leiomyosarcomas (LMS), 82 endometrial stromal sarcomas (ESS), 22 adenosarcomas (AS) and 18 undifferentiated uterine sarcomas (UUS). Up-regulated membranous beta-catenin was observed in 25% of the LMS (p=0.039), 21% of the ESS (p=0.072) and 39% of the UUS (p=0.025). Cytoplasmic beta-catenin was up-regulated in 36% of the LMS (p=0.008) and 33% of the UUS (p=0.028). Nuclear beta-catenin expression was observed in 23% of the LMS (p=0.051), 61% of ESS (p=0.628) and in the sarcoma component of 68% of the AS. In patients with LMS, membranous beta-catenin was associated with poor crude survival in univariate (p=0.045), but not in multivariate analyses. In patients with ESS, nuclear beta-catenin expression was related to spread of tumour (p=0.033), but not to survival. The observation of up-regulated beta-catenin expression in US might suggest a so far undocumented role for the Wnt/beta-catenin pathway in these malignancies.

Nuclear accumulation of e-cadherin correlates with loss of cytoplasmic membrane staining and invasion in pituitary adenomas

CONTEXT

Loss of the cell adhesion protein E-cadherin is associated with invasion and metastasis in a number of malignancies. Recent studies have highlighted that loss of E-cadherin cell membrane expression may be accompanied by its detection in the nucleus, suggesting cellular redistribution during neoplasia. Pituitary tumors, although typically benign, may be locally invasive, and loss of membranous E-cadherin has been reported as a marker of invasion in prolactinomas.

OBJECTIVE

Our objective was to study E-cadherin expression in pituitary adenomas, specifically whether nuclear redistribution occurs in this setting.

METHODS

Immunohistochemistry, RT-PCR, and direct sequencing were performed.

RESULTS

Strong cytoplasmic membrane staining was present in all eight normal samples but completely absent in 21 of 44 adenomas (48%) with weak staining in an additional 11 adenomas using an antibody against the extracellular domain of E-cadherin. To identify nuclear translocation of the protein, immunohistochemistry was performed using an antibody against the cytoplasmic domain. Nuclear staining was present in 38 of 44 adenomas (86%) and absent in normal tissue. Nuclear E-cadherin inversely correlated with loss of E-cadherin cytoplasmic membrane staining and was associated with tumor invasion (P = 0.009). To investigate the mechanism of nuclear redistribution of E-cadherin, we performed RT-PCR of mRNA and sequenced tumor DNA. E-cadherin mRNA expression was reduced in only one of 30 samples (3%). No mutations were detected.

CONCLUSIONS

E-cadherin was frequently lost at the cytoplasmic membrane but detected in the nucleus, suggesting that cleavage of the extracellular domain and nuclear translocation of E-cadherin is a common event that may determine local invasion in pituitary adenomas.

Endocrine neoplasms of the pancreas: pathologic and genetic features

CONTEXT

Pancreatic endocrine neoplasms (PENs) are diagnostically challenging tumors whose natural history is largely unknown. Histopathology allows the distinction of 2 categories: poorly differentiated high-grade carcinomas and well-differentiated neoplasms. The latter include more than 90% of PENs whose clinical behavior varies from indolent to malignant and cannot be predicted by their morphology.

OBJECTIVES

To review the literature and report on additional primary material about the clinicopathologic features, classification, staging, grading, and genetic features of PENs.

DATA SOURCES

Literature review of relevant articles indexed in PubMed (US National Library of Medicine) and primary material from the authors' institution.

CONCLUSIONS

The diagnosis of PEN is generally easy, but unusual features may induce misdiagnosis. Immunohistochemistry solves the issue, provided that the possibility of a PEN has been considered. Morphology allows the distinction of poorly differentiated aggressive carcinomas from well-differentiated neoplasms. The World Health Organization classification criteria allow for the discernment of the latter into neoplasms and carcinomas with either benign or uncertain behavior. The recently proposed staging and grading systems hold great promise for permitting a stratification of carcinomas into clinically significant risk categories. To date, inactivation of the MEN1 gene remains the only ascertained genetic event involved in PEN genesis. It is inactivated in roughly one-third of PENs. The degree of genomic instability correlates with the aggressiveness of the neoplasm. Gene silencing by promoter methylation has been advocated, but a formal demonstration of the involvement of specific genes is still lacking. Expression profiling studies are furnishing valuable lists of mRNAs and noncoding RNAs that may advance further the research to discover novel markers and/or therapeutic targets.

Expression of P-aPKC-iota, E-cadherin, and beta-catenin related to invasion and metastasis in hepatocellular carcinoma

OBJECTIVES

Atypical protein kinase C iota (aPKC-iota) and its associated intracellular molecules, E-cadherin and beta-catenin, are important for cell polarization in tumorigenesis and progression. Expression of aPKC-iota, P-aPKC-iota (activated aPKC-iota), E-cadherin, and beta-catenin in hepatocellular carcinoma (HCC) was measured, and correlation with clinicopathological characteristics of HCC was analyzed.

METHODS

Paraffin-embedded tumor tissue was obtained from patients with HCC after resection without preoperative radiotherapy or chemotherapy. Gene expression was detected by polymerase chain reaction (PCR), and protein expression was detected by immunohistochemistry and Western blot analysis. Expressions of aPKC-iota, P-aPKC-iota, E-cadherin, and beta-catenin were analyzed with relation to the clinicopathological data.

RESULTS

The gene and protein expression of aPKC-iota are obviously higher in HCC tissues than that in peritumoral tissues and normal tissues by semiquantitative PCR and immunohistochemistry methods. Accumulation of aPKC-iota in HCC cytoplasm and nucleolus inhibited the later formation of belt-like adherens junctions (AJs) and/or tight junctions (TJs) in cell-cell contact. E-cadherin was reduced and accumulation of cytoplasm beta-catenin was increased in HCC. The expression of aPKC-iota was closely related to pathological differentiation, tumor size, invasion, and metastasis of HCC.

CONCLUSION

Accumulation of cytoplasm aPKC-iota may reflect pathological differentiation, invasion, and metastasis potential of HCC. In this regard, our study on HCC revealed the potential usefulness of aPKC-iota, E-cadherin, and beta-catenin as a prognostic marker, closely related to pathological differentiation, invasion, metastasis, and prognosis of HCC.

E-Cadherin Expression in Endometrial Malignancies: Comparison between Endometrioid and Non-Endometrioid Carcinomas

This study examined the frequency of E-cadherin expression in endometrial biopsy or hysterectomy specimens from patients diagnosed with endometrial adenocarcinoma and in normal endometrial tissue specimens. E-cadherin expression was detected by immunohistochemistry using monoclonal antibody to E-cadherin. Specimens were classified as positive when ≥ 5% of the tumour cells showed staining for E-cadherin, irrespective of the pattern of staining. Twenty-three endometrioid carcinomas and nine non-endometrioid (four papillary serous and five clear cell) carcinomas were studied, along with 10 normal endometrial tissue specimens as controls. E-cadherin expression was significantly less frequent in non-endometrioid carcinomas compared with endometrioid carcinomas and controls. There was no statistically significant difference in the frequency of E-cadherin expression between endometrioid carcinomas and controls. In conclusion, this study demonstrated that uterine non-endometrioid (papillary serous and clear cell) carcinomas were less likely to express E-cadherin compared with endometrioid carcinomas and normal endometrial tissue. This may help to explain the more aggressive behaviour of non-endometrioid carcinomas.

HNPCC-associated synchronous early-stage signet-ring cell carcinomas of colonic origin. A comparative morphological and immunohistochemical study of an intramucosal and a submucosal example

Signet-ring cell carcinoma (SRCC) developing in the colorectum (CR) is infrequently identified at an early stage (no deeper than submucosa). Most such examples involve the submucosa. Merely 13 cases of intramucosal CR SRCC are at hand. We recently had the opportunity to study a specimen with two synchronous early-stage SRCC, developed in a 65-year-old hereditary nonpolyposis colorectal cancer male patient with a known disease-causing mutation in MLH1. A right hemicolectomy specimen comprised a 15-mm intramucosal cecal lesion, featuring zones of conventional tubular adenoma and intraepithelial SRCC as well as tumor cells multifocally permeating the lamina propria and a 12-mm submucosally expanding SRCC of the ascending colon. The intramucosal and intraepithelial as well as stromal lesional cells displayed a normal membranous expression of beta-catenin and E-cadherin; submucosally infiltrating cells featured alterations in this complex with loss of membranous expression of both proteins and a shift with nuclear accumulation of beta-catenin, suggesting a disruption of the Wingless signaling pathway taking place at the transition from the intramucosal to the submucosal level.

Revision 2: an immunohistochemical approach and evaluation of solid pseudopapillary tumour of the pancreas

Solid pseudopapillary tumours (SPT) of the pancreas are uncommon, but with widespread and increased imaging, several of these lesions are coming to light incidentally and are subject to needle biopsies. On limited material and especially the solid or clear cell, variants of SPT can morphologically mimic most notably pancreatic neuroendocrine tumours and even metastatic renal cell carcinoma or melanoma. In this context, immunohistochemistry is important and useful in helping to reach the correct diagnosis. Several antibodies have been used in the immunohistochemical evaluation of SPT. As with most tumours, no one marker is specific, but rather a core panel is advocated. Recently, both beta-catenin and E-cadherin have been shown to be of value in SPT. Nuclear and cytoplasmic decoration of tumour cells by beta-catenin is seen in almost 100% of cases. This protein relocalisation away from the cell membrane is underscored by mutations of the beta-catenin gene. Mutations of the CDH1 gene are very uncommon in SPT, but the immunohistochemically detected changes to the protein are consistent and present in 100% of cases. Using an E-cadherin antibody to the extracellular domain of the molecule results in complete membrane loss, while the antibody directed to the cytoplasmic fragment produces distinct nuclear staining of the tumour cells. In addition, there is concordance of staining abnormalities between the two antibodies. When combined with CD10 and progesterone receptor positivity, a diagnosis of SPT can be rendered with confidence even in small biopsy samples.

Nuclear E-cadherin immunoexpression: from biology to potential applications in diagnostic pathology

E-cadherin is a well-recognized molecule that is important in cell adhesion. Its abrogation has been linked to increased invasiveness in several malignancies. The normal immunohistochemical localization of E-cadherin is the cell membrane, however, both cytoplasmic and nuclear immunostaining has been reported. Loss of membrane staining and/or nuclear staining for E-cadherin is seen in 100% of cases of solid pseudopapillary tumors (SPTs) of the pancreas. In the context of SPT, E-cadherin staining is of diagnostic use. Nuclear staining has been seen in cases of pancreatic neuroendocrine tumors, Merkel cell carcinomas, clear cell renal cell carcinoma, esophageal squamous carcinoma, colorectal and gastric cancer, and synovial sarcoma. The difference in the staining patterns seen (complete loss vs. nuclear staining) is due to the type of E-cadherin antibody used. Antibodies recognizing the extracellular domain show loss of E-cadherin staining in SPT, whereas the antibody to the cytoplasmic domain results in nuclear staining in all cases of SPT. Therefore, E-cadherin staining is of diagnostic use in the immunohistochemical work-up of SPT. Nuclear E-cadherin staining of pancreatic neuroendocrine tumors identified a subset of cases with more aggressive potential, whereas nuclear staining of clear cell renal cancers identified a subset of tumors with a better prognosis. The exact mechanism by which E-cadherin enters the nucleus is not known but it is likely that it is closely related to several partner molecules such as beta-catenin, p120, and presenilin-1.