Roles of E- and P-cadherin in the human skin

Altering Cell Junctional Tension in Spheroids through E-Cadherin Engagement Modulation

Cadherin-mediated tension at adherens junctions (AJs) is fundamental for cell-cell adhesion and maintaining epithelial integrity. Despite the importance of manipulating AJs to dissect cell-cell interactions, existing three-dimensional (3D) multicellular models have not adequately addressed the precise manipulation of these junctions. To fill this gap, we introduce E-cadherin-modified tension gauge tethers (TGTs) at the junctions within spheroids. The system enables both quantification and modulation of junctional tension with specific DNA triggers. Using rupture-induced fluorescence, we successfully measure mechanical forces in 3D spheroids. Furthermore, mechanically strong TGTs can maintain normal E-cadherin-mediated adhesion. Employing toehold-mediated strand displacement allowed us to disrupt E-cadherin-specific cell-cell adhesion, consequently altering intracellular tension within the spheroids. Our methodology offers a robust and precise way to manipulate cell-cell adhesion and intracellular mechanics in spheroid models.

MARCH family E3 ubiquitin ligases selectively target and degrade cadherin family proteins

Cadherin family proteins play a central role in epithelial and endothelial cell-cell adhesion. The dynamic regulation of cell adhesion is achieved in part through endocytic membrane trafficking pathways that modulate cadherin cell surface levels. Here, we define the role for various MARCH family ubiquitin ligases in the regulation of cadherin degradation. We find that MARCH2 selectively downregulates VE-cadherin, resulting in loss of adherens junction proteins at cell borders and a loss of endothelial barrier function. Interestingly, N-cadherin is refractory to MARCH ligase expression, demonstrating that different classical cadherin family proteins are differentially regulated by MARCH family ligases. Using chimeric cadherins, we find that the specificity of different MARCH family ligases for different cadherins is conferred by the cadherin transmembrane domain. Further, juxta-membrane lysine residues are required for cadherin degradation by MARCH proteins. These findings expand our understanding of cadherin regulation and highlight a new role for mammalian MARCH family ubiquitin ligases in differentially regulating cadherin turnover.

A sustainable strategy for generating highly stable human skin equivalents based on fish collagen

Tissue engineered skin equivalents are increasingly recognized as potential alternatives to traditional skin models such as human ex vivo skin or animal skin models. However, most of the currently investigated human skin equivalents (HSEs) are constructed using mammalian collagen which can be expensive and difficult to extract. Fish skin is a waste product produced by fish processing industries and identified as a cost-efficient and sustainable source of type I collagen. In this work, we describe a method for generating highly stable HSEs based on fibrin fortified tilapia fish collagen. The fortified fish collagen (FFC) formulation is optimized to enable reproducible fabrication of full-thickness HSEs that undergo limited contraction, facilitating the incorporation of human donor-derived skin cells and formation of biomimetic dermal and epidermal layers. The morphology and barrier function of the FFC HSEs are compared with a commercial skin model and validated with immunohistochemical staining and transepithelial electrical resistance testing. Finally, the potential of a high throughput screening platform with FFC HSE is explored by scaling down its fabrication to 96-well format.

Light Sheet-Based Laser Patterning Bioprinting Produces Long-Term Viable Full-Thickness Skin Constructs

Tissue engineering holds great promise for biomedical research and healthcare, offering alternatives to animal models and enabling tissue regeneration and organ transplantation. 3D bioprinting stands out for its design flexibility and reproducibility. Here, an integrated fluorescent light sheet bioprinting and imaging system is presented that combines high printing speed (0.66 mm3 /s) and resolution (9 µm) with light sheet-based imaging. This approach employs direct laser patterning and a static light sheet for confined voxel crosslinking in photocrosslinkable materials. The developed bioprinter enables real-time monitoring of hydrogel crosslinking using fluorescent recovery after photobleaching (FRAP) and brightfield imaging as well as in situ light sheet imaging of cells. Human fibroblasts encapsulated in a thiol-ene click chemistry-based hydrogel exhibited high viability (83% ± 4.34%) and functionality. Furthermore, full-thickness skin constructs displayed characteristics of both epidermal and dermal layers and remained viable for 41 days. The integrated approach demonstrates the capabilities of light sheet bioprinting, offering high speed, resolution, and real-time characterization. Future enhancements involving solid-state laser scanning devices such as acousto-optic deflectors and modulators will further enhance resolution and speed, opening new opportunities in light-based bioprinting and advancing tissue engineering.

E-Cadherin Is Expressed in Epithelial Cells of the Choroid Plexus in Human and Mouse Brains

Evidence showing the functional significance of the choroid plexus is accumulating. Epithelial cells with tight and adherens junctions of the choroid plexus play important roles in cerebrospinal fluid production and circadian rhythm formation. Although specific types of cadherin expressed in adherens junctions of choroid plexus epithelium (CPE) have been examined, they remained uncertain. Recent mass spectrometry and immunolocalization analysis revealed that non-epithelial cadherins, P- and N-cadherins, are expressed in the lateral membrane of CPE, whereas E-cadherin expression has not been confirmed in CPE of humans or mice. In this study, we examined E-cadherin expression in CPE of mice and humans by RT-PCR, immunohistochemical-, and Western blotting analyses. We confirmed, by using RT-PCR analysis, the mRNA expression of E-cadherin in the choroid plexus of mice. The immunohistochemical expression of E-cadherin was noted in the lateral membrane of CPE of mice and humans. We further confirmed, in Western blotting, the specific immunoreactivity for E-cadherin. Immunohistochemically, the expression of E- and N-cadherins or vimentin was unevenly distributed in some CPE, whereas that of E- and P-cadherins or β-catenin frequently co-existed in other CPE. These findings indicate that E-cadherin is expressed in the lateral membrane of CPE, possibly correlated with the expression of other cadherins and cytoplasmic proteins.

MARCH family E3 ubiquitin ligases selectively target and degrade cadherin family proteins

Cadherin family proteins play a central role in epithelial and endothelial cell-cell adhesion. The dynamic regulation of cell adhesion is achieved in part through endocytic membrane trafficking pathways that modulate cadherin cell surface levels. Here, we define the role for various MARCH family ubiquitin ligases in the regulation of cadherin degradation. We find that MARCH2 selectively downregulates VE-cadherin, resulting in loss of adherens junction proteins at cell borders and a loss of endothelial barrier function. Interestingly, N-cadherin is refractory to MARCH ligase expression, demonstrating that different classical cadherin family proteins are differentially regulated by MARCH family ligases. Using chimeric cadherins, we find that the specificity of different MARCH family ligases for different cadherins is conferred by the cadherin transmembrane domain. Further, juxta-membrane lysine residues are required for cadherin degradation by MARCH proteins. These findings expand our understanding of cadherin regulation and highlight a new role for mammalian MARCH family ubiquitin ligases in differentially regulating cadherin turnover.

Expression of β-Catenin, E-Cadherin, and α-Smooth Muscle Actin in Basal Cell Carcinoma Before Photodynamic Therapy in Non-recurrent and Recurrent Tumors: Exploring the Ability of Predicting Photodynamic Therapy Outcome

Photodynamic therapy (PDT) is an effective and cosmetically beneficial treatment of low-risk basal cell carcinomas (BCCs). To optimize PDT response, it is important to correctly select tumors. We sought to find markers that could identify such tumors beyond contributions from clinical and histological examination. Studies have shown that β-catenin, E-cadherin, and α-smooth muscle actin (SMA) expression can indicate BCC aggressiveness/BCC invasiveness. We wanted to use these markers in an explorative study to investigate whether they were differently expressed among non-recurring compared with recurring BCCs, to evaluate their ability of predicting PDT outcome. Fifty-two BCCs were stained with antibodies against β-catenin, E-cadherin, and α-SMA, and evaluated using immunoreactive score (IRS), subcellular localization, and stromal protein expression. Results showed that IRS of E-cadherin was significantly different among recurring compared with non-recurring BCCs and with area under a receiver operating characteristic curve of 0.71 (95% confidence interval: 0.56-0.86, p=0.025). Stromal β-catenin expression significantly increased among recurring BCCs. Some recurring BCCs had intense expression in the deep invading tumor edge. In conclusion, E-cadherin, and stromal and deep edge β-catenin expression were most prominent in BCCs that recurred post-PDT, suggesting they could potentially predict PDT outcome. Further studies are needed to investigate whether these results are of clinical value.

Breast cancer prognosis and P-cadherin expression: systematic review and study-level meta-analysis

OBJECTIVE

P-cadherin can act both as a tumour suppressor and an oncogene. The clinical prognostic value of P-cadherin overexpression in breast cancer (BC) remains unclear. We conducted a study-level meta-analysis to determine whether P-cadherin expression can help predict prognosis in BC.

METHODS

A systematic literature search was performed to review eligible studies and clarify the relationship between P-cadherin overexpression and overall survival (OS), disease-free survival (DFS), pathological features, molecular subtypes and molecular phenotypes in BC.

RESULTS

Thirty-one studies including 12 332 patients were included. P-cadherin overexpression was correlated with significantly worse OS (HR=1.77, p<0.00001) and DFS (HR=1.96, p<0.00001) than P-cadherin-negative. P-cadherin overexpression could lead to high histological grade (OR=3.33, p<0.00001) and lymph node metastasis (OR=1.62, p<0.00001). Moreover, P-cadherin overexpression was associated with low odds of the luminal A subtype and high odds of the human epidermal growth factor receptor-2 (HER2)-positive and triple-negative subtypes. P-cadherin expression led to low expression of oestrogen and progesterone receptor (OR=0.37 and OR=0.36, respectively, both p<0.00001) and high expression of HER2 (OR=2.31, p<0.00001), Ki-67 (OR=2.79, p<0.00001), epidermal growth factor receptor (OR=5.85, p<0.00001) and cytokeratin 5/6 (OR=6.79, p<0.00001).

CONCLUSIONS

P-cadherin was found to be associated with invasiveness and metastasis. P-cadherin expression can probably be a useful biomarker for predicting poor survival and may act as an independent prognostic predictor.

Immune milieu and microbiome of the distal urethra in Ugandan men: impact of penile circumcision and implications for HIV susceptibility

BACKGROUND

Coronal sulcus (CS) anaerobe abundance and IL-8 levels are linked to HIV acquisition, and are dramatically reduced after penile circumcision (PC). The distal urethra may be the site of some HIV acquisition before PC, and presumably most acquisition post PC. We describe the immune milieu and microbiome of the distal urethra in uncircumcised Ugandan men, and define the impact of PC. Participants consisted of HIV-negative, genital symptom-free adult Ugandan men undergoing PC (n = 51). Urethral and coronal sulcus swabs were collected at baseline and at 6- and 12-months post-PC. Soluble immune factors were quantified by multiplex ELISA, and bacterial abundance assessed by 16S rRNA qPCR and sequencing.

RESULTS

At baseline, the urethra was enriched compared to the CS for most cytokines (including IL-8 and MIP-1β) and soluble E-cadherin (sE-cadherin, an epithelial disruption marker), although CS levels of IL-1α and IL-1β were higher. Baseline total bacterial abundance was ≥ 20-fold higher in the CS than the urethra (median 27,100 vs. 1200 gene copies/swab, p = 0.001), and anaerobes comprised 58% of CS bacteria vs. 42% of urethral bacteria. PC did not alter urethral IL-8 (median 806 at baseline vs. 1130 pg/ml at 12 months; p = 0.062) and urethral sE-cadherin increased (113,223 vs. 158,385 pg/ml, p = 0.009), despite five- and sevenfold drops in total bacterial and anaerobe abundance after PC, respectively. However, PC dramatically reduced CS levels of sE-cadherin (15,843 vs. 837 pg/ml, p < 0.001) and most cytokines (IL-8; 34 vs. 3 pg/ml, p < 0.001), while reducing total bacterial and anaerobe abundance by 13-fold and 60-fold, respectively (both P ≤ 0.004).

CONCLUSIONS

The urethra is immunologically rich with characteristics of an HIV-susceptible tissue site. However, PC had no impact on urethral immunology and may have reduced epithelial integrity, despite modest reductions in total bacteria and anaerobes, suggesting that HIV protection from PC is not mediated via immune or microbiome alterations in the urethra. Video abstract.

Cadherin Expression and EMT: A Focus on Gliomas

Cadherins are calcium-binding proteins with a pivotal role in cell adhesion and tissue homeostasis. The cadherin-dependent mechanisms of cell adhesion and migration are exploited by cancer cells, contributing to tumor invasiveness and dissemination. In particular, cadherin switch is a hallmark of epithelial to mesenchymal transition, a complex development process vastly described in the progression of most epithelial cancers. This is characterized by drastic changes in cell polarity, adhesion, and motility, which lead from an E-cadherin positive differentiated epithelial state into a dedifferentiated mesenchymal-like state, prone to metastization and defined by N-cadherin expression. Although vastly explored in epithelial cancers, how these mechanisms contribute to the pathogenesis of other non-epithelial tumor types is poorly understood. Herein, the current knowledge on cadherin expression in normal development in parallel to tumor pathogenesis is reviewed, focusing on epithelial to mesenchymal transition. Emphasis is taken in the unascertained cadherin expression in CNS tumors, particularly in gliomas, where the potential contribution of an epithelial-to-mesenchymal-like process to glioma genesis and how this may be associated with changes in cadherin expression is discussed.

Weak immunohistochemical expression of galectin-3 near blisters in Hailey-Hailey disease

BACKGROUND

Hailey-Hailey disease (HHD) is an uncommon hereditary and benign skin condition characterized by blisters and erosions on intertriginous areas. It is related to a mutation of the ATP2C1 gene, which encodes a Ca²⁺ pump. It is characterized by multiple foci of skin acantholysis in the epidermis, with dyskeratosis and suprabasilar clefting. Galectin-3 is a beta-galactoside-binding protein that has an essential role in cell-to-cell and cell-to-matrix adhesion. We assessed galectin-3 immunohistochemical expression in HHD to explore its impact on the pathogenesis of this hereditary blistering disorder.

METHOD

In a retrospective study, seven specimens from seven patients diagnosed with HHD were stained with antibodies to galectin-3. We evaluated the nuclear and cytoplasmic expression of galectin-3, as well as the staining intensity around blisters and distant normal skin.

RESULTS

We observed a significant decrease in cytoplasmic and nuclear expression of galectin-3 as well as stain intensity around blisters compared with distant normal skin.

CONCLUSIONS

While the acantholysis process in HHD is related to abnormality in cadherin expression caused by altered Ca²⁺ pump concentration, lower expression of galectin-3 may cause the extension of blisters by initiating cell-to-cell disassembly in the epidermis.

Adhesion Molecules in Non-melanoma Skin Cancers: A Comprehensive Review

Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the most frequently diagnosed cancers, generating significant medical and financial problems. Cutaneous carcinogenesis is a very complex process characterized by genetic and molecular alterations, and mediated by various proteins and pathways. Cell adhesion molecules (CAMs) are transmembrane proteins responsible for cell-to-cell and cell-to-extracellular matrix adhesion, engaged in all steps of tumor progression. Based on their structures they are divided into five major groups: cadherins, integrins, selectins, immunoglobulins and CD44 family. Cadherins, integrins and CD44 are the most studied in the context of non-melanoma skin cancers. The differences in expression of adhesion molecules may be related to the invasiveness of these tumors, through the loss of tissue integrity, neovascularization and alterations in intercellular signaling processes. In this article, each group of CAMs is briefly described and the present knowledge on their role in the development of non-melanoma skin cancers is summarized.

Immunoexpression of adhesion molecules during human fetal hair development

INTRODUCTION

Hair follicles are produced in a cyclical manner and the machinery involved in the reproduction of these follicles is present since the fetal stage. Although extensive research has been done on the human hair follicle, very little is known about the importance of adhesion molecules in its development.

MATERIAL AND METHODS

We analyzed here, the immunoexpression of beta-1 integrin, p-cadherin, e-cadherin, and beta-catenin in hair follicles from 26 formalin-fixed and paraffin-embedded skin samples from human embryos and fetus between 12-23 weeks of gestational age.

RESULTS

The adhesion molecules beta-1 integrin and e-cadherin/p-cadherin were expressed from 12 weeks and seemed to play a role in regulating epidermis invagination. Beta-catenin immunostaining was negative in all cases; down regulation of this protein may be necessary for fetal hair development and thus facilitating hair follicle down growth.

DISCUSSION/CONCLUSION

Adhesion molecules are essential for hair follicle down growth and proliferation; integrins and cadherins play a major role in this process. More studies are needed to describe hair follicle development.

The cell-cell junctions of mammalian testes: II. The lamellar smooth muscle monolayer cells of the peritubular wall are laterally connected by vertical adherens junctions-a novel architectonic cell-cell junction system

The testes of sexually mature males of six mammalian species (men, bulls, boars, rats, mice, guinea pigs) have been studied using biochemical as well as light and electron microscopical techniques, in particular immunolocalizations. In these tissues, the peritubular walls represent lamellar encasement structures wrapped around the seminiferous tubules as a bandage system of extracellular matrix layers, alternating with monolayers of very flat polyhedral "lamellar smooth muscle cells" (LSMCs), the number of which varies in different species from 1 to 5 or 6. These LSMCs are complete SMCs containing smooth muscle α-actin (SMA), myosin light and heavy chains, α-actinin, tropomyosin, smoothelin, intermediate-sized filament proteins desmin and/or vimentin, filamin, talin, dystrophin, caldesmon, calponin, and protein SM22α, often also cytokeratins 8 and 18. In the monolayers, the LSMCs are connected by adherens junctions (AJs) based on cadherin-11, in some species also with P-cadherin and/or E-cadherin, which are anchored in cytoplasmic plaques containing β-catenin and other armadillo proteins, in some species also striatin family proteins, protein myozap and/or LUMA. The LSMC cytoplasm is rich in myofilament bundles, which in many regions are packed in paracrystalline arrays, as well as in "dense bodies," "focal adhesions," and caveolae. In addition to some AJ-like end-on-end contacts, the LSMCs are laterally connected by numerous vertical AJ-like junctions located in variously sized and variously shaped, overlapping (alter super alterum) lamelliform cell protrusions. Consequently, the LSMCs of the peritubular wall monolayers are SMCs sensu stricto which are laterally connected by a novel architectonic system of arrays of vertical AJs located in overlapping cell protrusions.

P-cadherin and the journey to cancer metastasis

P-cadherin is a classical cell-to-cell adhesion molecule with a homeostatic function in several normal tissues. However, its behaviour in the malignant setting is notably dependent on the cellular context. In some tumour models, such as melanoma and oral squamous cell carcinoma, P-cadherin acts as a tumour suppressor, since its absence is associated with a more aggressive cancer cell phenotype; nevertheless, the overexpression of this molecule is linked to significant tumour promoting effects in the breast, ovarian, prostate, endometrial, skin, gastric, pancreas and colon neoplasms. Herein, we review the role of P-cadherin in cancer cell invasion, as well as in loco-regional and distant metastatic dissemination. We focus in P-cadherin signalling pathways that are activated to induce invasion and metastasis, as well as cancer stem cell properties. The signalling network downstream of P-cadherin is notably dependent on the cellular and tissue context and includes the activation of integrin molecules, receptor tyrosine kinases, small molecule GTPases, EMT transcription factors, and crosstalk with other cadherin family members. As new oncogenic molecular pathways mediated by P-cadherin are uncovered, putative therapeutic options can be tested, which will allow for the targeting of invasion or metastatic disease, depending on the tumour model.

Low-grade cylindromatous adnexal carcinoma with unusual histopathological features: report of a case with comparative immunohistochemical study and meta-analysis of the literature

We present an extremely rare case of low-grade cylindromatous adnexal carcinoma (CAC) on the right chest wall of a 77-year-old man. Histopathologically, the neoplasm was initially diagnosed as a cylindroma that developed over the course of 13 years. A diagnosis of low-grade CAC was rendered after the documentation of a local recurrence and histopathology of the recurrent tumor. To further assess the evolution of low-grade CAC over time, we compared the morphology, mitotic account, proliferative markers and adhesion molecule immunoreactivity among paired primary and recurrent tumors. Unlike those earlier reported, our case showed the maintenance of tumor morphology after a recurrence without areas of obvious malignant transformation or metaplastic change. We showed here for the first time the expression of adhesion molecules of CAC/spiradenoma and a comparison of proliferation indices between a primary tumor and its local recurrence. This peculiar tumor differs from previously reported cases and harbors a malignant potential although the histopathological features of malignancy are subtle. Our meta-analysis of the literature provided background information regarding this rare entity. Alterations of E-cadherin and GCDFP-15 expression may provide additional helpful clues in differential diagnosis and determining the clinical behavior of this unusual neoplasm. Further studies are warranted to confirm the potential discriminative role of these markers.

Insights into protein interaction networks reveal non-receptor kinases as significant druggable targets for psoriasis

Psoriasis is a chronic disease of the skin characterized by hyper proliferation and inflammation of the epidermis and dermal components of the skin. T-cell-dependent inflammatory process in skin governs the pathogenesis of psoriasis. An in-silico search strategy was utilized to identify psoriatic therapeutic drug targets. The gene expression profiling of psoriatic skin identified a total of 427 differentially expressed genes (DEGs). Gene ontology investigation of DEGs identified genes involved in calcium binding, apoptosis, keratinisation, lipid transportation and homeostasis apart from immune mediated processes. The protein interaction networks identified proteins involved in various signaling mechanisms with high degree of interconnections. The gene modules derived from the main network were enriched with rich kinome. These sub-networks were dominated by the presence of non-receptor kinase family members which are major signal transmitters in immune response. The computational approach has aided in the identification of non-receptor kinases as potential targets for psoriasis drug development.

The role of P-cadherin in skin biology and skin pathology: lessons from the hair follicle

Adherens junctions (AJs) are one of the major intercellular junctions in various epithelia including the epidermis and the follicular epithelium. AJs connect the cell surface to the actin cytoskeleton and comprise classic transmembrane cadherins, such as P-cadherin, armadillo family proteins, and actin microfilaments. Loss-of-function mutations in CDH3, which encodes P-cadherin, result in two allelic autosomal recessive disorders: hypotrichosis with juvenile macular dystrophy (HJMD) and ectodermal dysplasia, ectrodactyly, and macular dystrophy (EEM) syndromes. Both syndromes feature sparse hair heralding progressive macular dystrophy. EEM syndrome is characterized in addition by ectodermal and limb defects. Recent studies have demonstrated that, together with its involvement in cell-cell adhesion, P-cadherin plays a crucial role in regulating cell signaling, malignant transformation, and other major intercellular processes. Here, we review the roles of P-cadherin in skin and hair biology, with emphasize on human hair growth, cycling and pigmentation.

Role of the calcium-sensing receptor in calcium regulation of epidermal differentiation and function

The epidermis is a stratified squamous epithelium composed of proliferating basal and differentiated suprabasal keratinocytes. It serves as the body's major physical and chemical barrier against infection and harsh environmental insults, as well as preventing excess water loss from the body into the atmosphere. Calcium is a key regulator of the proliferation and differentiation in keratinocytes. Elevated extracellular Ca(2+) concentration ([Ca(2+)]o) raises the levels of intracellular free calcium ([Ca(2+)]i), promotes cell-cell adhesion, and activates differentiation-related genes. Keratinocytes deficient in the calcium-sensing receptor fail to respond to [Ca(2+)]o stimulation and to differentiate, indicating a role for the calcium-sensing receptor in transducing the [Ca(2+)]o signal during differentiation. The concepts derived from in vitro gene knockdown experiments have been evaluated and confirmed in three mouse models in vivo.

Topobiology of human pigmentation: P-cadherin selectively stimulates hair follicle melanogenesis

P-cadherin serves as a major topobiological cue in mammalian epithelium. In human hair follicles (HFs), it is prominently expressed in the inner hair matrix that harbors the HF pigmentary unit. However, the role of P-cadherin in normal human pigmentation remains unknown. As patients with mutations in the gene that encodes P-cadherin show hypotrichosis and fair hair, we explored the hypothesis that P-cadherin may control HF pigmentation. When P-cadherin was silenced in melanogenically active organ-cultured human scalp HFs, this significantly reduced HF melanogenesis and tyrosinase activity as well as gene and/or protein expression of gp100, stem cell factor, c-Kit, and microphthalmia-associated transcription factor (MITF), both in situ and in isolated human HF melanocytes. Instead, epidermal pigmentation was unaffected by P-cadherin knockdown in organ-cultured human skin. In hair matrix keratinocytes, P-cadherin silencing reduced plasma membrane β-catenin, whereas glycogen synthase kinase 3 beta (GSK3β) and phospho-β-catenin expression were significantly upregulated. This suggests that P-cadherin-GSK3β/Wnt signaling is required for maintaining the expression of MITF to sustain intrafollicular melanogenesis. Thus, P-cadherin-mediated signaling is a melanocyte subtype-specific topobiological regulator of normal human pigmentation, possibly via GSK3β-mediated canonical Wnt signaling.

Calcium regulation of keratinocyte differentiation

Calcium is the major regulator of keratinocyte differentiation in vivo and in vitro. A calcium gradient within the epidermis promotes the sequential differentiation of keratinocytes as they traverse the different layers of the epidermis to form the permeability barrier of the stratum corneum. Calcium promotes differentiation by both outside-in and inside-out signaling. A number of signaling pathways involved with differentiation are regulated by calcium, including the formation of desmosomes, adherens junctions and tight junctions, which maintain cell-cell adhesion and play an important intracellular signaling role through their activation of various kinases and phospholipases that produce second messengers that regulate intracellular free calcium and PKC activity, critical for the differentiation process. The calcium receptor plays a central role by initiating the intracellular signaling events that drive differentiation in response to extracellular calcium. This review will discuss these mechanisms.

The calcium-sensing receptor-dependent regulation of cell-cell adhesion and keratinocyte differentiation requires Rho and filamin A

Extracellular Ca(2+) (Ca(2+)(o)) functioning through the calcium-sensing receptor (CaR) induces E-cadherin-mediated cell-cell adhesion and cellular signals mediating cell differentiation in epidermal keratinocytes. Previous studies indicate that CaR regulates cell-cell adhesion through Fyn/Src tyrosine kinases. In this study, we investigate whether Rho GTPase is a part of the CaR-mediated signaling cascade regulating cell adhesion and differentiation. Suppressing endogenous Rho A expression by small interfering RNA (siRNA)-mediated gene silencing blocked the Ca(2+)(o)-induced association of Fyn with E-cadherin and suppressed the Ca(2+)(o)-induced tyrosine phosphorylation of β-, γ-, and p120-catenin and formation of intercellular adherens junctions. Rho A silencing also decreased the Ca(2+)(o)-stimulated expression of terminal differentiation markers. Elevating the Ca(2+)(o) level induced interactions among CaR, Rho A, E-cadherin, and the scaffolding protein filamin A at the cell membrane. Inactivation of CaR expression by adenoviral expression of a CaR antisense complementary DNA inhibited Ca(2+)(o)-induced activation of endogenous Rho. Ca(2+)(o) activation of Rho required a direct interaction between CaR and filamin A. Interference of CaR-filamin interaction inhibited Ca(2+)(o)-induced Rho activation and the formation of cell-cell junctions. These results indicate that Rho is a downstream mediator of CaR in the regulation of Ca(2+)(o)-induced E-cadherin-mediated cell-cell adhesion and keratinocyte differentiation.

P-cadherin expression as a prognostic biomarker in a 3992 case tissue microarray series of breast cancer

P-cadherin is a calcium-dependent cell-cell adhesion glycoprotein. P-cadherin expression is restricted to the myoepithelial cells in normal breast tissue, and aberrant staining has also been described in invasive tumors. Several small studies have reported P-cadherin as a marker of poor outcome in breast cancer patients but its prognostic significance in relation to other variables has not been established in a large series of breast cancers. A tissue microarray was constructed from 3992 cases of invasive breast carcinoma, and P-cadherin expression was evaluated using immunohistochemistry. Median follow-up was 12.5 years. The immunohistochemistry-based definitions of cancer subtypes were luminal (ER+ or PR+/HER2-), luminal/HER2+ (ER+ or PR+/HER2+), HER2+ (ER-/PR-/HER2+), and basal (ER-/PR-/HER2-/CK5/6+ or EGFR+). Clinical covariate and biomarker associations were assessed using contingency tables, and Pearson's χ(2) or Fisher's exact test. Survival associations were assessed using Kaplan-Meier plots, logrank and Breslow tests, and Cox proportional hazards regression analysis. P-cadherin was expressed in 34.8% (1290/3710, 50% cut point) of cases. P-cadherin staining was strongly associated with HER2+ and basal carcinoma subtypes (P<0.0005). P-cadherin-positive patients showed significantly poorer short-term (0-10 years) overall survival, disease-specific survival, distant relapse-free interval, and locoregional relapse-free interval in univariable models (P<0.05). In multivariable Cox models containing standard clinical covariates and cancer subtypes, P-cadherin did not show independent prognostic value. P-cadherin expression was positively associated with histological grade, chemotherapy, Ki-67, EGFR, CK5/6, p53, YB-1, and HER2 expression (P<0.002), and negatively associated with age at diagnosis, ER, PR, and Bcl-2 expression (P<0.0005). This study shows the value of P-cadherin as a marker of poor prognosis. The large sample size of this series clarifies contradictory findings of many smaller studies. P-cadherin positivity is associated with high-grade tumor subtypes and well-established markers of poor prognosis, and may represent a promising antibody therapeutic target.

Post-transcriptional regulation controlled by E-cadherin is important for c-Jun activity in melanoma

A central event in the development of malignant melanoma is the loss of the tumor-suppressor protein E-cadherin. Here, we report that this loss is linked to the activation of the proto-oncogene c-Jun, a key player in tumorigenesis. In vivo, malignant melanomas show strong expression of the c-Jun protein in contrast to melanocytes. Interestingly, c-Jun mRNA levels did not differ in the melanoma cell lines when compared to melanocytes, suggesting that c-Jun could be regulated at the post-transcriptional level. To uncover the link between E-cadherin and c-Jun, we re-expressed E-cadherin in melanoma cells and detected decreased protein expression and activity of c-Jun. Furthermore, c-Jun accumulation is dependent on active E-cadherin-mediated cell-cell adhesion and regulated via the cytoskeleton. Additionally, we determined that, with respect to c-Jun regulation, there are two melanoma subgroups. One subgroup regulates c-Jun expression via the newly discovered E-cadherin-dependent signaling pathway, whereas the other subgroup uses the MAPKinases to regulate its expression. In summary, our data provide novel insights into the tumor-suppressor function of E-cadherin, which contributes to the suppression of c-Jun protein translation and transcriptional activity independent of MAPKinases.

Active Notch1 confers a transformed phenotype to primary human melanocytes

The importance of mitogen-activated protein kinase signaling in melanoma is underscored by the prevalence of activating mutations in N-Ras and B-Raf, yet clinical development of inhibitors of this pathway has been largely ineffective, suggesting that alternative oncogenes may also promote melanoma. Notch is an interesting candidate that has only been correlated with melanoma development and progression; a thorough assessment of tumor-initiating effects of activated Notch on human melanocytes would clarify the mounting correlative evidence and perhaps identify a novel target for an otherwise untreatable disease. Analysis of a substantial panel of cell lines and patient lesions showed that Notch activity is significantly higher in melanomas than their nontransformed counterparts. The use of a constitutively active, truncated Notch transgene construct (N(IC)) was exploited to determine if Notch activation is a "driving" event in melanocytic transformation or instead a "passenger" event associated with melanoma progression. N(IC)-infected melanocytes displayed increased proliferative capacity and biological features more reminiscent of melanoma, such as dysregulated cell adhesion and migration. Gene expression analyses supported these observations and aided in the identification of MCAM, an adhesion molecule associated with acquisition of the malignant phenotype, as a direct target of Notch transactivation. N(IC)-positive melanocytes grew at clonal density, proliferated in limiting media conditions, and also exhibited anchorage-independent growth, suggesting that Notch alone is a transforming oncogene in human melanocytes, a phenomenon not previously described for any melanoma oncogene. This new information yields valuable insight into the basic epidemiology of melanoma and launches a realm of possibilities for drug intervention in this deadly disease.

Relationship of adhesion molecules expression with epithelial differentiation markers during fetal skin development

BACKGROUND

Cadherins and integrins are important for maintenance of tissue integrity and in signal transduction during skin development. Distribution of these molecules in human skin development was investigated and associated with markers of differentiation, cytokeratins (CK) and involucrin (INV).

METHODS

Using immunohistochemistry expression of E- and P-cadherins, integrins beta-1 and -4, CK10, CK14 and INV was assessed in skin fragments of 10 human fetuses (gestational weeks ranged from 4 to 24, all weighing up to 500 g).

RESULTS

At initial phases of development, integrins beta-1 and -4 and E- and P-cadherins were present on epithelial cell membranes in all layers. CK14 and CK10 were expressed in all epithelial layers and INV weakly detected in the superficial layer. In more advanced stages, integrins were detected in all layers, but a marked polarized expression was seen in basal layer. E-cadherin was detected in all layers, but the cornified stratum and P-cadherin were observed in the lower layers. CK14 was expressed in basal layer, CK10 in suprabasal stratum and INV was observed in cornified layer.

CONCLUSIONS

Cadherins and integrins are essential for skin development, being spatially and temporally regulated. Their expression is related with the expression of maturation markers of the epidermis.

Transformation-specific matrix metalloproteinases (MMP)-7 and MMP-13 are expressed by tumour cells in epidermolysis bullosa-associated squamous cell carcinomas

BACKGROUND

Patients with recessive dystrophic epidermolysis bullosa (RDEB) have an increased risk of developing rapidly progressive and metastatic cutaneous squamous cell carcinomas (SCC). It is unclear why these SCC behave more aggressively than sporadic SCC. Matrix metalloproteinases (MMP) are a family of endopeptidases that contribute to growth, invasion and metastasis of SCC. The role of MMP in RDEB-associated SCC is not known.

OBJECTIVES

To investigate the expression of MMP-7, MMP-13 and MMP-9 in RDEB-associated SCC in comparison with sporadic SCC and Bowen's disease.

METHODS

Immunohistochemical analysis of 25 RDEB-associated SCC, 61 sporadic SCC and 28 sporadic lesions of Bowen's disease was carried out using monoclonal antibodies for MMP-7, MMP-9, MMP-13 and E-cadherin and syndecan-1.

RESULTS

MMP-7 was detected in all RDEB-associated SCC, in tumour cells within the invasive edge, where E-cadherin and syndecan-1 were markedly diminished or absent. MMP-7 expression was also observed in 98% of sporadic SCC and in 68% of Bowen's diseases. MMP-7 staining was significantly stronger in RDEB-associated SCC than in sporadic SCC, and was most abundant in poorly differentiated tumours. MMP-13 was detected in tumour cells in 96% of RDEB-associated SCC and in all sporadic cutaneous SCC. MMP-9 was detected in the inflammatory cells in all SCC examined.

CONCLUSIONS

These results identify MMP-7 and MMP-13 as tumour cell-specific markers for SCC progression and as potential therapeutic targets in RDEB-associated SCC. The pattern of immunolabelling suggests that MMP-7 may shed E-cadherin and syndecan-1 from the SCC cell surface.

ADAM10-mediated E-cadherin release is regulated by proinflammatory cytokines and modulates keratinocyte cohesion in eczematous dermatitis

Acute eczema is an inflammatory skin disease characterized by the formation of small intraepidermal blisters, reduction of the adhesion molecule E-cadherin from the keratinocyte surface, and impaired keratinocyte cohesion. Here, we reveal that the disintegrin and metalloprotease ADAM10 is critically involved in regulating E-cadherin cell-surface expression in cultured primary human keratinocytes and in diseased human skin. Proinflammatory cytokines, transforming growth factor-beta, and lipopolysaccharide led to increased release of soluble E-cadherin by activating mitogen-activated protein kinase signaling in cultured keratinocytes. Moreover, these stimuli decreased the amount of pro-ADAM10 and increased the level of the active protease, leading to loss of E-cadherin from the cell surface and decreased keratinocyte cohesion. In situ examination and immunoblot analyses of E-cadherin and ADAM10 expression in lesional skin of eczema revealed that the reduction of E-cadherin expression in areas of blister formation closely correlated with increased level of ADAM10 expression and elevated E-cadherin shedding. Our data suggest that ADAM10-mediated E-cadherin proteolysis leads to the impaired cohesion of keratinocytes observed in eczematous dermatitis and provide previously unreported insights into the understanding of the molecular mechanisms involved in inflammatory diseases with loss in epithelial integrity.

Inactivation of the calcium sensing receptor inhibits E-cadherin-mediated cell-cell adhesion and calcium-induced differentiation in human epidermal keratinocytes

Extracellular Ca(2+) (Ca(2+)(o)) is a critical regulator that promotes differentiation in epidermal keratinocytes. The calcium sensing receptor (CaR) is essential for mediating Ca(2+) signaling during Ca(2+)(o)-induced differentiation. Inactivation of the endogenous CaR-encoding gene CASR by adenoviral expression of a CaR antisense cDNA inhibited the Ca(2+)(o)-induced increase in intracellular free calcium (Ca(2+)(i)) and expression of terminal differentiation genes, while promoting apoptosis. Ca(2+)(o) also instigates E-cadherin-mediated cell-cell adhesion, which plays a critical role in orchestrating cellular signals mediating cell survival and differentiation. Raising Ca(2+)(o) concentration ([Ca(2+)](o)) from 0.03 to 2 mm rapidly induced the co-localization of alpha-, beta-, and p120-catenin with E-cadherin in the intercellular adherens junctions (AJs). To assess whether CaR is required for the Ca(2+)(o)-induced activation of E-cadherin signaling, we examined the impact of CaR inactivation on AJ formation. Decreased CaR expression suppressed the Ca(2+)(o)-induced AJ formation, membrane translocation, and the complex formation of E-cadherin, catenins, and the phosphatidylinositol 3-kinase (PI3K), although the expression of these proteins was not affected. The assembly of the E-cadherin-catenin-PI3K complex was sensitive to the pharmacologic inhibition of Src family tyrosine kinases but was not affected by inhibition of Ca(2+)(o)-induced rise in Ca(2+)(i). Inhibition of CaR expression blocked the Ca(2+)(o)-induced tyrosine phosphorylation of beta-, gamma-, and p120-catenin, PI3K, and the tyrosine kinase Fyn and the association of Fyn with E-cadherin and PI3K. Our results indicate that the CaR regulates cell survival and Ca(2+)(o)-induced differentiation in keratinocytes at least in part by activating the E-cadherin/PI3K pathway through a Src family tyrosine kinase-mediated signaling.

Laminin alpha5 is essential for the formation of the zebrafish fins

The vertebrate fin fold, the presumptive evolutionary antecedent of the paired fins, consists of two layers of epidermal cells extending dorsally and ventrally over the trunk and tail of the embryo, facilitating swimming during the embryonic and larval stages. Development of the fin fold requires dramatic changes in cell shape and adhesion during early development, but the proteins involved in this process are completely unknown. In a screen of mutants defective in fin fold morphogenesis, we identified a mutant with a severe fin fold defect, which also displays malformed pectoral fins. We find that the cause of the defect is a non-sense mutation in the zebrafish lama5 gene that truncates laminin alpha5 before the C-terminal laminin LG domains, thereby preventing laminin alpha5 from interacting with its cell surface receptors. Laminin is mislocalized in this mutant, as are the membrane-associated proteins, actin and beta-catenin, that normally form foci within the fin fold. Ultrastructural analysis revealed severe morphological abnormalities and defects in cell-cell adhesion within the epidermis of the developing fin fold at 36 hpf, resulting in an epidermal sheet that can not extend away from the body. Examining the pectoral fins, we find that the lama5 mutant is the first zebrafish mutant identified in which the pectoral fins fail to make the transition from an apical epidermal ridge to an apical fold, a transformation that is essential for pectoral fin morphogenesis. We propose that laminin alpha5, which is concentrated at the distal ends of the fins, organizes the distal cells of the fin fold and pectoral fins in order to promote the morphogenesis of the epidermis. The lama5 mutant provides novel insight into the role of laminins in the zebrafish epidermis, and the molecular mechanisms driving fin formation in vertebrates.

Dynamics of cell interactions and communications during melanoma development

Melanoma development not only involves genetic and epigenetic changes that take place within the cell, but also involves processes determined collectively by micro-environmental factors, including cell-cell interactions and communications. During the transition from normal cells to benign and malignant lesions, and subsequently to metastatic cancer, stepwise changes in intercellular communications provide tumor cells with the ability to overcome cell-cell adhesion and micro-environmental controls from the host and to invade surrounding tissues and disperse to distant locations. Cadherins are major cell-cell adhesion molecules involved in the development and maintenance of skin. E-cadherin expressed in normal melanocytes mediates growth and invasion control by keratinocytes. Progressive loss of E-cadherin and gain of N-cadherin during melanoma development not only free melanoma cells from control by keratinocytes, but also provide new adhesion properties, resulting in switched partnerships with fibroblasts and vascular endothelial cells. The cadherin subtype switching also dictates gap junctional specificity in melanocytic cells during tumor development. This selective intercellular communication may contribute to the regulation of cell growth, differentiation, apoptosis, and migration of melanocytic cells in both physiologic and pathologic conditions. Abnormal up-regulation of the immunoglobin repeat-containing cell adhesion molecules Mel-CAM and L1-CAM potentiates invasion and migration of melanoma. Thus, abnormal expression of intercellular adhesion receptors and dysregulated intercellular communication underlies melanoma development and progression.

Expression pattern of adhesion molecules in junctional epithelium differs from that in other gingival epithelia

BACKGROUND AND OBJECTIVE

The gingival epithelium is the physiologically important interface between the bacterially colonized gingival sulcus and periodontal soft and mineralized connective tissues, requiring protection from exposure to bacteria and their products. However, of the three epithelia comprising the gingival epithelium, the junctional epithelium has much wider intercellular spaces than the sulcular epithelium and oral gingival epithelium. Hence, the aim of the present study was to characterize the cell adhesion structure in the junctional epithelium compared with the other two epithelia.

MATERIAL AND METHODS

Gingival epithelia excised at therapeutic flap surgery from patients with periodontitis were examined for expression of adhesion molecules by immunofluorescence.

RESULTS

In the oral gingival epithelium and sulcular epithelium, but not in the junctional epithelium, desmoglein 1 and 2 in cell-cell contact sites were more abundant in the upper than the suprabasal layers. E-cadherin, the main transmembranous molecule of adherens junctions, was present in spinous layers of the oral gingival epithelium and sulcular epithelium, but was scarce in the junctional epithelium. In contrast, desmoglein 3 and P-cadherin were present in all layers of the junctional epithelium as well as the oral gingival epithelium and sulcular epithelium. Connexin 43 was clearly localized to spinous layers of the oral gingival epithelium, sulcular epithelium and parts of the junctional epithelium. Claudin-1 and occludin were expressed in the cell membranes of a few superficial layers of the oral gingival epithelium.

CONCLUSION

These findings indicated that the junctional epithelium contains only a few desmosomes, composed of only desmoglein 3; adherens junctions are probably absent because of defective E-cadherin. Thus, the anchoring junctions connecting junctional epithelium cells are lax, causing widened intercellular spaces. In contrast, the oral gingival epithelium, which has a few tight junctions, functions as a barrier.

E-cadherin and its downstream catenins are proteolytically cleaved in human HaCaT keratinocytes exposed to UVB

It has been reported that ultraviolet B (UVB) irradiation causes the loss of E-cadherin of melanocytes, leading them to escape from neighboring keratinocytes during melanoma development. However, little has been paid on its effect on E-cadherin of keratinocytes. In the present study we therefore focus on whether UVB affects expression of E-cadherin-catenin complex in human HaCaT keratinocytes. We found that E-cadherin, beta-, and gamma-catenin but not alpha-catenin were proteolytically cleaved in UVB-irradiated HaCaT keratinocytes. The effect was only observed in keratinocyte undergoing apoptosis. Cleavage of beta- and gamma-catenin was fully abolished by caspase-3 and caspase-8 inhibitors, whereas cleavage of E-cadherin was inhibited by neither caspase nor metalloproteinase inhibitors. Functional analysis showed that the cleavage resulted in the disruption of the physical association between E-cadherin and catenins, indicating that E-cadherin signaling was compromised in UVB-irradiated HaCaT keratinocytes. Because E-cadherin in keratinocytes plays important roles in mediating cell-cell adhesion in epidermis of skin, the loss of E-cadherin and signaling components in keratinocytes may lead to the disruption of skin integrity after UVB exposure.

Importance of P-cadherin, beta-catenin, and Wnt5a/frizzled for progression of melanocytic tumors and prognosis in cutaneous melanoma

PURPOSE

It has been proposed that melanoma cells shift from E-cadherin to N-cadherin expression during tumor development, and recent gene profiling has shown increased expression of Wnt5a/Frizzled in aggressive melanomas possibly by interactions with beta-catenin. We therefore wanted to investigate the role of cadherin subtypes, beta-catenin, and Wnt5a/Frizzled in melanocytic tumors, with focus on prognosis in nodular melanomas.

EXPERIMENTAL DESIGN

The immunohistochemical expression of E-cadherin, N-cadherin, P-cadherin, beta-catenin, and Wnt5a/Frizzled was examined using tissue microarrays of 312 melanocytic tumors.

RESULTS

Cytoplasmic expression of P-cadherin was associated with increasing tumor thickness (P=0.005) and level of invasion (P=0.019), whereas membranous staining was associated with thinner (P=0.012) and more superficial (P=0.018) tumors. Increased cytoplasmic P-cadherin was associated with reduced survival (P=0.047). Lack of nuclear beta-catenin expression was related to increased tumor thickness (P=0.002) and poor patient survival in univariate (P=0.0072) and multivariate (P=0.004) analyses. Membranous expression of N-cadherin was significantly increased from primary tumors to metastatic lesions, whereas E-cadherin staining tended to be decreased. Wnt5a and its receptor Frizzled were highly coexpressed, and nuclear expression of both markers was significantly reduced from benign nevi to melanomas, with a shift from nuclear to cytoplasmic expression in malignant tumors. In addition, Wnt5a expression was significantly associated with nuclear beta-catenin expression.

CONCLUSIONS

Alterations in the expression and subcellular localization of cell adhesion markers are important in the development and progression of melanocytic tumors, and strong cytoplasmic P-cadherin expression and loss of nuclear beta-catenin staining were associated with aggressive melanoma behavior and reduced patient survival.

Influence of the cytoplasmic domain of E-cadherin on endogenous N-cadherin expression in malignant melanoma

E-cadherin is known to be an important molecule in epithelial-mesenchymal transition (EMT). Malignant transformation of melanocytes frequently attends with loss of E-cadherin expression and induction of expression of mesenchymal molecules like N-cadherin. The switch of the cadherin class is an interesting phenomenon of melanoma cells and in EMT in general. Therefore, we analysed the capacity of E-cadherin to regulate expression of N-cadherin in melanocytic cells. Our experiments revealed that melanoma cells downregulate endogenous N-cadherin expression after transient transfection of full-length E-cadherin, but also of the cytoplasmic domain of E-cadherin. Therefore, we concluded that the extracellular domain of E-cadherin and cell-cell contacts are not necessary for negative regulation of N-cadherin. Melanoma cells re-expressing full-length or cytoplasmatic E-cadherin have reduced NFkappaB activity in comparison to mock-transfected cells. Downregulation of NFkappaB activity, either directly or by re-expression of E-cadherin, led to a suppression of N-cadherin promoter activity and N-cadherin expression. Consequently, an NFkappaB-binding site in the N-cadherin promoter was characterized. In summary, our results suggest that N-cadherin is directly regulated by E-cadherin. Loss of E-cadherin induces NFkappaB activity and N-cadherin expression in tumorigenic EMT.

T-cadherin negatively regulates the proliferation of cutaneous squamous carcinoma cells

T-cadherin is a unique member of the cadherin superfamily that lacks the transmembrane and cytoplasmic domains, and is instead linked to the cell membrane via a glycosyl-phosphatidylinositol anchor. We previously reported that T-cadherin was specifically expressed on the basal keratinocytes of the epidermis, and the expression of T-cadherin was significantly reduced in invasive cutaneous squamous cell carcinoma (SCC) and in the lesional skin of psoriasis vulgaris. In this study, to obtain an insight into the role of T-cadherin in keratinocytes, we used transfection methods and examined the effect of overexpression or knockdown of T-cadherin in immortalized keratinocyte cell lines derived from SCC. T-cadherin overexpressed cells showed clearly reduced cell proliferation, but the influence of cell-cell adhesiveness and cell mobility was not detected. Using a tetracycline-regulated expression system, we also confirmed that the suppression of cell proliferation was dependent on the expression level of T-cadherin. Cell cycle analysis demonstrated that over expression of T-cadherin induced a delay in the G(2)/M phase. Our findings suggest that T-cadherin acts as an endogenous negative regulator of keratinocyte proliferation and its inactivation is the cause for keratinocyte hyperproliferation in SCC or in psoriasis vulgaris.

Endometriotic Cells Exhibit Metaplastic Change and Oxidative DNA Damage as Well as Decreased Function, Compared to Normal Endometrium

A widely accepted theory of the etiology of endometriosis is that it originates from the implantation and invasion of cells from retrograde menstruation to various sites in the body particularly the pelvic peritoneal cavity. Little is known of the function of these cells in ectopic sites. Normal endometrium was compared with endometriotic tissue using an antibody to Placental Cadherin (P Cadherin), a recently studied cadherin that is implicated in metaplasia and early neoplasia and also 8-hydroxyguanine, an indicator of oxidative DNA damage. Comparisons of endometrial tissue function were made using expression of transforming growth factor beta-1 (TGFbeta-1) and insulin-like growth factor-I (IGF-I). There was no labelling for anti-P Cadherin or anti-8-hydroxydeoxyguanosine in normal endometrium but marked labelling for both on the apical surface of the endometriotic epithelium. Studies of markers of normal endometrial function were all de-expressed in endometriosis. This study indicates that endometriosis cells are abnormal and exhibit oxidative DNA damage, metaplasia and markedly reduced function compared to normal endometrium.

Expression of e-cadherin and beta-catenin in cutaneous squamous cell carcinoma and its precursors

The E-cadherin-beta-catenin complex regulates the architectural integrity of epithelia by mediating intercellular adhesion. Down-regulation of its expression may contribute to invasion and metastatic behavior of carcinoma cells. Several studies demonstrated an abnormal expression of E-cadherin, beta-catenin, or both in various carcinomas, including non-melanoma skin cancer. The aim of the present study was to investigate the involvement of E-cadherin-catenin adhesion system in the progression of human cutaneous squamous cell carcinoma (SCC). For that purpose, sections from normal skin, skin showing solar elastosis (SE), solar keratosis (SK), and SCC were stained with monoclonal antibodies against E-cadherin and beta-catenin. Evaluation of the staining results was performed using a semi-quantitative method in which pattern and intensity of staining, percentage of positive cells, and cytoplasmic staining were evaluated. Normal skin and skin showing mild and moderate solar elastosis strongly expressed membranous E-cadherin and beta-catenin. E-cadherin expression was progressively reduced in the epidermis of skin with severe solar elastosis through solar keratosis to SCC. The same phenomenon was observed for beta-catenin starting from solar keratosis. In some cases of SCC, additional cytoplasmic staining was observed. We found no correlation between E-cadherin and beta-catenin expression and tumor differentiation or between SCC from sun-exposed and sun-protected skin. Statistical analysis revealed correlation between expression of both E-cadherin and beta-catenin and the morphology of the lesion. These results support a gradual evolution from severely sun-damaged skin to SCC, not only on a morphologic level, but also at the molecular level.

Reversal of melanocytic malignancy by keratinocytes is an E-cadherin-mediated process overriding beta-catenin signaling

Loss of E-cadherin in melanoma cells frees them from keratinocytes-mediated proliferation and phenotypic control, which can be restored by forced E-cadherin expression. In this study, E-cadherin and its derivatives were introduced into metastatic melanoma line 1205Lu. E-cadherin and E-cadherin-alpha-catenin fusion protein were functional in mediating cell adhesion, downregulating MCAM(4) in coculture, and inhibiting proliferation regardless of beta-catenin expression levels and activation status. In contrast, cytoplasmic domain-deleted (E-cadDeltaCYT) derivative was not able to reverse malignancy. The results indicate that E-cadherin-mediated cell adhesion is required for keratinocyte-mediated control of melanocytic cells, which can override proliferative activity of beta-catenin.

Junctional complex revisited by high-resolution scanning electron microscopy

The present study correlates the ultrastructural morphology of junctional complexes as revealed by transmission electron microscopy (TEM) with that observed by high-resolution scanning electron microscopy (HRSEM), thanks to a new modification of the osmium tetroxide maceration technique. The removal of all cytoplasmic organelles by this technique allows the inspection of the inner side of the plasmalemma. With this treatment, a continuous band of tightly packed particles is observed at the most apical portion of lateral membranes. Just below this band, irregular clusters of apparently identical particles are placed all around the cellular contour. The topographical correspondence among these clusters and spot desmosomes seen by TEM identifies them as desmosomes. The continuous band seems to represent the combination of both zonulae, occludens and adherens. Regarding the nature of the particles, we suppose that they probably consist of peripheral membrane proteins clustered at the cytoplasmic surface of intercellular junctions and involved in the linkage between cytoskeleton and plasmalemma.

Reciprocal altered expression of T-cadherin and P-cadherin in psoriasis vulgaris

BACKGROUND

The most characteristic change in psoriasis vulgaris is markedly increased, persistent keratinocyte proliferation. The underlying mechanism of excessive epidermal growth is controversial. We previously found and reported that T-cadherin was expressed in keratinocytes and confined to the basal layer of mouse and human skin. Invasive cutaneous squamous cell carcinoma showed a loss of T-cadherin expression. Another study showed that T-cadherin was a negative growth regulator of epidermal growth factor in T-cadherin transfectant neuroblastoma cells.

OBJECTIVES

To obtain insight into the role of T-cadherin in keratinocyte proliferation and to investigate further the pathogenesis of psoriasis vulgaris, we examined the expression of T-cadherin, as well as E- and P-cadherin, in psoriasis vulgaris.

METHODS

Four untreated active psoriatic skin samples from psoriasis vulgaris patients and four normal human skin samples from plastic surgery were collected, cryosectioned and immunohistochemically stained by antihuman T-, P- and E-cadherin antibodies. Further, the immunofluorescence intensities of T- and P-cadherin on the basal layer of the epidermis were quantitatively measured by the histogram function of LSM 510 software installed in a Zeiss laser scanning confocal microscope. The data were statistically analysed by Student's t-test.

RESULTS

It was observed that T-cadherin was weakly and discontinuously expressed on the basal layer of psoriatic skin, while it was intensively expressed on all basal keratinocytes in normal human skin. In contrast, P-cadherin was strongly expressed throughout the entire epidermal layer in psoriatic skin samples, although its expression is restricted to the basal cell layer in normal human skin. There were no obvious differences in E-cadherin expression between normal human skin and psoriatic skin. Statistical analyses showed that the immunofluorescence intensity of T-cadherin in the basal cell layer of psoriatic skin (35 +/- 9.08) was significantly decreased compared with that in normal human skin (131.75 +/- 3.49, P = 2.46 x 10(-6)). There was a significant increase (P = 0.00139) in the immunofluorescence intensity of P-cadherin in the basal layer of psoriatic skin (68.25 +/- 12.13) compared with normal human skin (26 +/- 4.90).

CONCLUSIONS

The present study demonstrates that there is downregulation of T-cadherin expression and upregulation of P-cadherin expression in psoriatic skin, which are considered to be involved in the hyperproliferation of keratinocytes in psoriasis vulgaris.

Intramuscular metastasis of cutaneous squamous cell carcinoma: a case report

Cutaneous squamous cell carcinoma (SCC) is a common cancer. Although most patients with primary cutaneous SCC have an excellent prognosis, for those with metastatic disease, the long-term prognosis is poor. The most common sites of metastasis are regional lymph nodes, lung, liver, brain, skin, and bone. However, metastatic soft tissue SCC from cutaneous lesions is extremely rare, with only two reported cases. We report a case in which the patient had a primary SCC lesion on his left palm in 1986. A second primary SCC on his left forearm was confirmed in 2001, with subsequent metastasis to the proximal muscles and bone invasion in spite of the initial wide excision.

Calcium: a potential central regulator in wound healing in the skin

Calcium has an established role in the normal homeostasis of mammalian skin and serves as a modulator in keratinocyte proliferation and differentiation. Gradients of calcium concentration increasing from 0.5 mM in the basal layer to > 1.4 mM in the stratum granulosum are consistent with migration patterns in response to minor abrasion (normal wear). Dermal fibroblasts require calcium but are approximately 100 times less sensitive than keratinocytes. Normal calcium metabolism in the skin is dependent on cell membrane and cytosolic calcium binding proteins (calmodulin, cadherins, etc.), but their modulation through parathyroid hormone, vitamin D or growth factors in normal or damaged tissue is not well documented. In wound repair, calcium is predominantly involved as Factor IV in the hemostatic phase, but it is expected to be required in epidermal cell migration and regeneration patterns in later stages of healing. Calcium alginate dressings are designed to liberate calcium early in the acute phase to promote hemostasis, but it is presently unclear whether the supplementary calcium influences the intracellular environment at later stages of wound repair, notably during the remodeling phase. Although experimental studies suggest that control of calcium is obligatory in wound management, we know very little as to how calcium in the wound bed is modulated through hormones, vitamin D, or various growth factors. Also, there is limited information as to how calcium released either from dressings, platelets, or from the circulation through the action of parathyroid hormone, growth factors or other modulators influences cell migration and remodeling in skin wounds, although experimental models suggest that management of calcium is essential in wound management.

Upregulation of P-cadherin expression in the lesional skin of pemphigus, Hailey-Hailey disease and Darier's disease

BACKGROUND

Autoimmune blistering diseases, pemphigus vulgaris (PV) and pemphigus foliaceus (PF), are known to be caused by binding of autoantibodies to the desmosomal cadherins, desmoglein 3 and desmoglein 1, respectively. Recently, mutations in the genes coding Ca2+ pumps leads to inherited blistering diseases, Hailey-Hailey disease (HHD) and Darier's disease (DD). Cadherins are a family of Ca2+-dependent cell adhesion molecules and P-cadherin is one of the major cadherins expressed in the epidermis. Although detailed mechanisms of acantholysis of these blistering diseases have not been fully clarified, abnormal expression of cadherins caused by altered Ca2+ concentration due to the binding of autoantibodies to cell surface or by mutations in Ca2+ pumps is suggested to be involved in mechanisms of acantholysis of these autoimmune and inherited blistering diseases. The purpose of the present study was to determine whether altered P-cadherin expression is present in these diseases.

METHOD

Distribution patterns of P-cadherin in skin specimens from patients with PV (n=2), PF (n=2), HHD (n=4) and DD (n=3), were examined with confocal laser scanning microscopy using two anti-P-cadherin antibodies, 6A9 and NCC-CAD-299.

RESULTS

In normal control skin, P-cadherin expression was restricted to the basal layer. In contrast, positive immunostaining of P-cadherin was observed not only in the basal cells, but also in the suprabasal cells in lesional skin of all the acantholytic diseases.

CONCLUSIONS

The present results clearly demonstrated that upregulation of P-cadherin expression occurs in the acantholysis in all the four blistering diseases PV, PF, HHD and DD. Upregulation of P-cadherin may be involved in the pathomechanism of both the autoimmune blistering diseases and the inherited blistering diseases.