Cadherins in cutaneous biology

A fluorescence imaging technique suggests that sweat leakage in the epidermis contributes to the pathomechanism of palmoplantar pustulosis

Sweat is an essential protection system for the body, but its failure can result in pathologic conditions, including several skin diseases, such as palmoplantar pustulosis (PPP). As reduced intraepidermal E-cadherin expression in skin lesions was confirmed in PPP skin lesions, a role for interleukin (IL)-1-rich sweat in PPP has been proposed, and IL-1 has been implicated in the altered E-cadherin expression observed in both cultured keratinocytes and mice epidermis. For further investigation, live imaging of sweat perspiration on a mouse toe-pad under two-photon excitation microscopy was performed using a novel fluorescent dye cocktail (which we named JSAC). Finally, intraepidermal vesicle formation which is the main cause of PPP pathogenesis was successfully induced using our "LASER-snipe" technique with JSAC. "LASER-snipe" is a type of laser ablation technique that uses two-photon absorption of fluorescent material to destroy a few acrosyringium cells at a pinpoint location in three-dimensional space of living tissue to cause eccrine sweat leakage. These observatory techniques and this mouse model may be useful not only in live imaging for physiological phenomena in vivo such as PPP pathomechanism investigation, but also for the field of functional physiological morphology.

Assessment of tissue E-cadherin and its proteolytic serum fragment in pemphigus vulgaris before and after remission: A case-control study

BACKGROUND

E-cadherin is a classic cadherin that mediates keratinocyte adhesion.

AIMS

To assess the tissue expression of E-cadherin and its proteolytic serum fragment (soluble E-cadherin) in pemphigus vulgaris (PV) before and after clinical remission compared with controls.

PATIENTS

Thirty-seven PV patients and thirty controls were enrolled. Pemphigus disease area index (PDAI) was calculated for patients at baseline and after remission. Punch biopsy specimens were taken from patients before, and after remission, and from controls for assessment of tissue E-cadherin by immunofluorescence. Similarly, serum samples were collected for assessment of serum soluble E-cadherin by ELISA.

RESULTS

Presence, intensity, and mean intensity of tissue E-cadherin were significantly reduced in PV patients before treatment compared with controls (p < 0.001). Detected E-cadherin showed mainly a basal and suprabasal distribution with cell surface and a cytoplasmic expression. Serum E-cadherin was significantly higher in patients before treatment compared with controls (p = 0.006). With remission, tissue E-cadherin presence, intensity, mean intensity, and serum E-cadherin showed statistically significant improvement (p = 0.003, <0.001, <0.001, and 0.003 respectively). Tissue E-cadherin presence and serum E-cadherin level reached values equivalent to the controls (p = 0.49 and 0.44, respectively).

CONCLUSIONS

Disruption of tissue E-cadherin and upregulation of serum soluble E-cadherin can contribute to the pathogenesis of PV. Clinical remission of PV is associated with normalization of tissue and serum E-cadherin.

MicroRNAs in pemphigus and pemphigoid diseases

Autoimmune blistering diseases are a heterogenous group of dermatological disorders characterized by blisters and erosions of the skin and/or mucous membranes induced by autoantibodies against structural proteins of the desmosome or the dermal-epidermal adhesion complex including the hemidesmosome. They consist of the two major disease groups, pemphigus and pemphigoid diseases (PPDs). The diagnosis is based on clinical findings, histopathology, direct immunofluorescence, and detection of circulating autoantibodies. The pathogenesis is not fully elucidated, prognostic factors are lacking, and to date, there is no cure for PPDs. MicroRNAs (miRNAs) represent small, non-coding RNAs that play a pivotal role in the posttranscriptional regulation of gene expression. Their dysfunction was highlighted to play a significant role in the pathogenesis of various diseases. Even though a link between miRNAs and autoimmune blistering diseases had been suggested, the research of their involvement in the pathogenesis of PPDs is still in its infancy. miRNAs hold promise for uncovering new layers in the pathogenesis of PPDs, in order to improve diagnosis and also to develop potential therapeutic options. In the current article, we provide an overview regarding current knowledge of miRNAs in terms of complex pathogenesis of PPDs, and, also, their potential role as biomarkers, predictive factors and therapeutic targets.

Identification of a Novel Non-desmoglein Autoantigen in Pemphigus Vulgaris

Pemphigus vulgaris (PV) is an autoimmune bullous disease of the skin and mucous membranes characterized by the presence of circulating and tissue-bound autoantibodies against keratinocyte cell surface antigens, specifically desmoglein (Dsg) 1 and 3. The pathogenic role of anti-Dsg antibodies is well-established, while the mechanism of blister formation is only partly defined. We have applied a previously developed method for the efficient immortalization of IgG+ memory B cells to identify novel target antigens in PV. A human monoclonal antibody reactive with a hitherto unreported non-Dsg antigen was isolated. Immunoprecipitation and immunoblotting studies with keratinocyte extracts indicated α-catenin as the putative antigen, then confirmed by immunoblotting on the recombinant protein. Four of ten PV sera reacted with recombinant α-catenin. Although the isolated human monoclonal antibody was per se unable to dissociate keratinocyte monolayers and also to synergize with a pathogenic antibody in vitro, further studies are warranted to assess its possible in vivo contribution in the multifactorial pathogenesis and heterogeneous manifestations of PV disease.

Signal transduction growth factors: the effective governance of transcription and cellular adhesion in cancer invasion

Giulio Bizzozero classified the tissues concerning their capacity to self-renew during the adult life in labile, stable and permanent tissues. In 1940 Viktor Hamburger and Rita Levi Montalcini exposed the possibility to induce the growth of permanent cells thanks to a specific ligand Nerve Growth Factor (NGF). Stanley Cohen purified a protein the Epidermal Growth Factor (EGF), able to induce epidermis proliferation and to elicit precocious eye disclosure and teeth eruption, establishing the “inverse” relationships between the proliferation and differentiation. These two biological effects induced by EGF were according to EGFR signaling is involved in a large array of cellular functions such as proliferation, survival, adhesion, migration and differentiation. This review is focused on the key role of growth factors signaling and their downstream effectors in physiological and in pathological phenomena, the authors highlight the governance of Growth factors during the EMT in cancer invasion.

Telomerase and N-Cadherin Differential Importance in Adrenocortical Cancers and Adenomas

Adrenocortical carcinomas (ACC) are most frequently highly aggressive tumors. We assessed the telomerase reverse transcriptase (TERT) and N-cadherin role in the biology of ACC and their potential utility as molecular biomarkers, in different types of tumoral adrenocortical tissue. A total of 48 adrenal cortex samples (39 tumoral and 9 normal adrenal glands) were studied. TERT promoter mutations were searched by PCR and Sanger sequencing in two hotspots positions (-124 and -146). Also, telomerase and N-cadherin expression were evaluated by immunohistochemistry. TERT promoter mutations were not detected in any of the samples either malignant or benign. Telomerase nuclear expression was present in 26.6% of ACC and in 45.5% of non-functioning adenomas. It was absent in benign Cushing's lesions and in normal adrenal glands. Contrarily, N-cadherin was always expressed in the cellular membranes of benign adenomas or normal adrenals but no expression was detected in the majority of ACC. Nuclear telomerase and membrane N-cadherin expression were positively correlated in ACCs. We conclude that in ACC, the loss of N-cadherin is a frequent phenomenon while the existence of TERT promoter mutations is not and nuclear telomerase expression is present in only a minority of cases. Since the loss of N-cadherin expression was identified in both high and low proliferative ACC, this marker should be considered important for diagnostic application. Our study also suggests the existence of a TERT non-canonical function in cell adhesion. J. Cell. Biochem. 118: 2064-2071, 2017. © 2017 Wiley Periodicals, Inc.

Comparative analysis of the expression of E-cadherin, β-catenin, and β1 integrin in congenital and acquired cholesteatoma

E-cadherin, β-catenin, and β1 integrin are important cell adhesion molecules to maintain epithelial structure and function. We investigated the expression of these cell adhesion molecules in cholesteatomas to understand the role of cell-cell and cell-extracellular matrix interaction in cholesteatomas. An immunohistochemical investigation was carried out on 35 cholesteatoma tissue samples (14 congenital, 21 acquired cholesteatomas) and 10 normal retroauricular skin (RAS) tissues which are obtained during middle ear surgery. The expression rate was measured to find out differences between retroauricular skin and cholesteatoma, as well as between congenital and acquired cholesteatoma. E-cadherin expression rate was significantly lower in the cholesteatoma (spinous layer 88.7 ± 17.9 %, granular layer 54.6 ± 22.6 %) than in the RAS (100 %, 74.4 ± 7.4 %) and in the acquired (83.3 ± 19.4 %, 48.1 ± 22.9 %) than in the congenital (96.7 ± 12.0 %, 64.4 ± 18.8 %). β-catenin expression rate was significantly lower in the cholesteatoma (spinous layer 84.1 ± 17.2 %, granular layer 28.7 ± 30.8 %) than in the RAS (100 %, 75.9 ± 6.1 %) and in the acquired (78.1 ± 17.0 %, 17.1 ± 22.3 %) than in the congenital (93.2 ± 13.5 %, 46.1 ± 34.2 %). The expression pattern of β-catenin is similar to that of E-cadherin. In β1 integrin, there was no significant difference of the expression rate between RAS and cholesteatoma, as well as between congenital and acquired cholesteatoma. In conclusion, the expression of E-cadherin and β-catenin is reduced in cholesteatoma, and the reduction is more pronounced in acquired cholesteatoma than in congenital cholesteatoma. Acquired cholesteatomas showed more aggressive characteristics than congenital cholesteatomas in terms of cell-cell adhesion.

E-cadherin polymorphisms and susceptibility to arsenic-related skin lesions in West Bengal, India

OBJECTIVES

Although suppression of E-cadherin gene (CDH1) expression and exposure to arsenic have separately been associated with skin lesions, the combined effects of this "gene-environment" interaction have not been explored previously.

STUDY DESIGN

A population-based cross-sectional survey.

METHOD

This study involved 100 cases with skin lesions and 100 controls who were family members with no lesions. The subjects were recruited from villages and hamlets in northern Nadia Province, West Bengal. Each participant was required to undergo a detailed face-to-face interview; provide spot urine sample; provide saliva sample; and sign a consent form. The type and severity of skin lesions were assessed during a general medical examination of each participant in the field. The following 16 single nucleotide polymorphisms (SNPs) of the CDH1 were measured using DNA extracted from saliva samples: rs16260, rs5030625, rs155364, rs155808, rs155807, rs2303646, rs2059254, rs9925923, rs12919719, rs7188750, rs9989407, rs7196495, rs7196661, rs13689, rs12599393, and rs1862748.

RESULTS

The main effects of SNPs on the risk for skin lesions were borderline for rs7196661 (p-value=0.092), rs7196495 (p-value=0.090), and rs12919719 (p-value=0.065); the strongest association was found for rs9989407 (p-value=0.058). Several SNPs, however, showed that the T>T genotype carriers are at higher relative risk for skin lesions compared to carriers of the C>C or C>T genotypes; these results need to be confirmed in a larger study. The main effects of some of the SNPs and genotype frequencies on the severity of skin lesions were found to be relatively weak.

CONCLUSIONS

This is the first study that indicates that CDH1 polymorphisms can contribute to the etiology of premalignant skin lesions in people chronically exposed to arsenic in drinking water, and that this gene may be a factor in individual susceptibility to cutaneous diseases.

Reciprocal Altered Expression of E-Cadherin and P-Cadherin in Mucous Membrane Pemphigoid

E- and P- cadherins are involved in the selective adhesion of epidermal cells. To gain insight into the role of cadherins on the acantholysis of keratinocytes and further investigate the pathogenesis of Mucous Membrane Pemphigoid, we examined the expression of P-cadherin and E-cadherin, in normal human oral mucosa, lesional and peri-lesional mucosa in MMP. Twenty-nine samples from paraffin-embedded specimens of MMP were used for the study. Five specimens of healthy oral mucosa were evaluated as control group. To evaluate the E- and P-Cadherin expression, a mean percentage of positive cells was determined from the percentage of positive cells derived from the analysis of 100 cells in ten random areas at x400 magnification. It was observed that E-cadherin was weakly and discontinuously expressed on the epithelial layers of pemphigoid mucosa, while it was intensively expressed on all keratinocytes in normal human skin. In contrast, P-cadherin was strongly expressed throughout the entire epidermal layer in MMP samples, although its expression is restricted to the basal cell layer in normal human skin. Statistical analyses showed that the percentage of E-cadherin positive cells in the epithelium of pemphigoid cases was significantly decreased compared with that in normal human mucosa. There was a significant increase in the percentage of P-cadherin positive cells in the epithelial layers of MMP compared with normal human mucosa. The present study showed that there is downregulation of E-cadherin expression and upregulation of P-cadherin expression in MMP mucosa, which may be involved in the pathogenesis of MMP.

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.

E-cadherin is an additional immunological target for pemphigus autoantibodies

Pemphigus foliaceus (PF) and pemphigus vulgaris (PV) are autoimmune blistering diseases characterized by autoantibodies against desmoglein (Dsg)1 and Dsg3, respectively. The role of classical cadherins as immunological targets of pemphigus autoantibodies is unknown. In this study, we tested the reactivity of sera from patients with PF, Fogo Selvagem (FS), and PV by immunoprecipitation coupled with immunoblotting (IP-IB) and ELISA techniques using a baculovirus-expressed ectodomain of E-cadherin. By IP-IB, anti-E-cadherin reactivity was detected in all tested sera of PF (n=13) and FS (n=15) patients, and in 79% of mucocutaneous-type PV patients (n=33), but in none of the mucosal-type PV patients (n=7). By ELISA, anti-E-cadherin IgG was detected in most pemphigus sera that produced strong E-cadherin bands by IP-IB. The immunoreactivity of PF/FS sera with E-cadherin was also demonstrated by IP-IB using human epidermal extracts. However, immunofluorescence staining of A431DE cells (E-cadherin positive, Dsg1 negative) with pemphigus sera showed negative results. Immunoadsorption and competitive ELISA analysis suggest that most of the anti-E-cadherin antibodies cross-react with Dsg1, whereas others may represent independent antibodies that do not cross-react with Dsg1. The functional relevance of these anti-E-cadherin IgG autoantibodies detected in these pemphigus sera remains to be defined.

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.

Rac1 signaling stimulates N-cadherin expression, mesenchymal condensation, and chondrogenesis

The molecular mechanisms controlling differentiation of mesenchymal precursor cells into chondrocytes (chondrogenesis) are not completely understood. We have recently shown that the small GTPase RhoA inhibits this process. Here we demonstrate that a different Rho GTPase family member, Rac1, promotes chondrogenesis. Pharmacological inhibition of Rac1 expression in micromass culture resulted in reduced mRNA levels of the chondrogenic markers collagen II and aggrecan, and decreased accumulation of glycosaminoglycans. Expression of the essential chondrogenic transcription factors Sox9, Sox5, and Sox6 was also reduced upon inhibition of Rac1 signaling. In contrast, overexpression of Rac1 in the chondrogenic ATDC5 cell line increased mRNA transcripts of Sox9, 5, and 6, collagen II, and aggrecan. Inhibition of Rac1 resulted in a reduction in the number, size, and organization of cellular condensations and decreased expression of N-cadherin. Overexpression of Rac1 resulted in an increase in N-cadherin expression levels. Furthermore, genetic ablation of Rac1 in primary micromass cultures resulted in reduced expression of chondrogenic markers. Additionally, we provide evidence that Cdc42 also promotes chondrogenesis. Overexpression of Cdc42 in ATDC5 cells resulted in increased expression of Sox5, Sox9, and collagen II but not Sox6, aggrecan, or N-cadherin. Therefore, we demonstrate that Rac1 and Cdc42 are positive regulators of chondrogenesis, but act at least in part through different cellular and molecular mechanisms.

The recruitment of phosphatidylinositol 3-kinase to the E-cadherin-catenin complex at the plasma membrane is required for calcium-induced phospholipase C-gamma1 activation and human keratinocyte differentiation

Calcium induces epidermal keratinocyte differentiation, but the mechanism is not completely understood. We have previously demonstrated that calcium-induced human keratinocyte differentiation requires an intracellular calcium rise caused by phosphatidylinositol 3-kinase (PI3K)-dependent activation of phospholipase C-gamma1. In this study we sought to identify the upstream signaling pathway necessary for calcium activation of PI3K and its subsequent activation of phospholipase C-gamma1. We found that calcium induces the recruitment of PI3K to the E-cadherin-catenin complex at the plasma membrane of human keratinocytes. Knocking-down E-cadherin, beta-catenin, or p120-catenin expression blocked calcium activation of PI3K and phospholipase C-gamma1 and calcium-induced keratinocyte differentiation. However, knocking-down gamma-catenin expression had no effect. Calcium-induced PI3K recruitment to E-cadherin stabilized by p120-catenin at the plasma membrane requires beta-catenin but not gamma-catenin. These data indicate that the recruitment of PI3K to the E-cadherin/beta-catenin/p120-catenin complex via beta-catenin at the plasma membrane is required for calcium-induced phospholipase C-gamma1 activation and, ultimately, keratinocyte differentiation.

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.

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.

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.

Cell adhesion molecules and oral cancer

Cell adhesion molecules (CAMs) are found on the surfaces of all cells, where they bind to extracellular matrix molecules or to receptors on other cells. As well as having a structural role, CAMs function as signaling receptors, transducing signals initiated by cellular interactions which regulate many diverse processes, including cell division, migration, and differentiation. Cell adhesion molecules are essential for maintaining stable tissue structure. However, cell adhesion must be dynamic to facilitate the mobility and turnover of cells. In dynamic situations, cells alter their cell-cell and cell-matrix interactions by virtue of altered expression and function of CAMs. The expression of CAMs is normally tightly regulated, thereby controlling cell proliferation, mobility, differentiation, and survival. Many of these processes are misregulated in malignant tumors, and it has been shown that many of the characteristics of tumor cells are attributable to the aberrant expression or function of CAMs. Integrins and E-cadherin are the most important CAMs expressed by stratified squamous epithelium. Altered expression of these molecules has been found in oral carcinoma, where loss of CAM expression is often seen in poorly differentiated lesions. However, up-regulation of certain integrins, such as alphavbeta6, has consistently been found in oral cancer, suggesting that it may play an active role in disease progression.

Role of integrin alphaE(CD103)beta7 for tissue-specific epidermal localization of CD8+ T lymphocytes

Tissue-specific T cell localization is crucial for immune surveillance of normal tissues and the pathogenesis of inflammatory disorders. In psoriatic skin, CD8+ lymphocytes predominantly reside within the epidermis, whereas CD4+ T cells are most abundant within the dermis. Molecular mechanisms guiding this spatial compartmentalization are not completely understood, however. Here, we demonstrate that 55% (+/-9.7%, n = 14) of the epidermal T cells, predominantly of the CD8+ phenotype, expressed the integrin alphaE(CD103)beta7. In contrast, only 5% (+/-2.0%) of the dermal T cells were alphaE(CD103)beta7+. Integrin alphaE(CD103)beta7 was not detected in normal skin (n = 10), and less than 1% of peripheral blood lymphocytes derived from normal (n = 11) or psoriatic (n = 10) donors expressed alphaE(CD103). When cultured T lymphoblasts (n = 12 donors) were stimulated with transforming growth factor beta1, expression of integrin alphaE(CD103)beta7 was induced on 52.8% (+/-16.2%) of CD8+ cells, but only on 6.1% (+/-2.3%) of CD4+ cells, suggesting selective inducibility on CD8+ lymphocytes. Whereas similar overall expression of transforming-growth-factor-beta1-specific mRNA was detected in normal and psoriatic skin by real-time quantitative polymerase chain reaction, immunohistochemistry revealed focal overexpression of transforming growth factor beta1 underneath psoriatic, but not normal, epidermis. This heterogenous transforming growth factor beta1 expression may contribute to induction of alphaE(CD103) in vivo. Adhesion of transforming-growth-factor-beta1-stimulated CD8+, but not CD4+, T cells to cultured keratinocytes and psoriatic epidermis in frozen sections could be significantly inhibited by antibodies that blocked the alphaE(CD103)/E-cadherin interaction. Co-culture of lymphoblasts and keratinocytes resulted in marginal enhancement of alphaE(CD103)beta7 expression in some cases. Overall, integrin alphaE(CD103)beta7 appears to contribute to tissue-specific epidermal localization of CD8+ T lymphocytes.

Potential role of the chemokine receptors CXCR3, CCR4, and the integrin alphaEbeta7 in the pathogenesis of psoriasis vulgaris

Various adhesion molecules have been implicated in T lymphocyte binding to dermal vascular endothelium in psoriasis vulgaris, but the chemotactic signals that promote subsequent homing into the adjacent dermis and overlying epidermis are poorly defined. We studied chemokine receptor (CCR1-CCR5, CXCR1-CXCR3), chemokine (interferon-gamma inducible protein 10 [IP-10]), monokine induced by interferon-gamma (MIG), thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), and adhesion molecule (cutaneous lymphocyte antigen [CLA], E-selectin, lymphocyte function-associated antigen-1 [LFA-1], intercellular adhesion molecule-1 [ICAM-1], very late antigen 4 [VLA-4], vascular cell adhesion molecule-1 [VCAM-1], alphaEbeta7, and E-cadherin) expression in psoriasis by immunohistology, flow cytometry, and molecular techniques. CXCR3 and CCR4 were expressed by dermal CD3+ lymphocytes, and their chemokine ligands, IP-10, MIG, TARC, and MDC, were up-regulated in psoriatic lesions. Keratinocytes stimulated with tumor necrosis factor-alpha and interferon-gamma up-regulated expression of IP-10, MIG, and MDC mRNA, whereas dermal endothelial cells, similarly stimulated, up-regulated expression of IP-10, MDC, and TARC mRNA, suggesting that these cell types were sources of the chemokines detected in biopsies. There was enhanced expression of E-selectin, CLA, LFA-1, ICAM-1, VLA-4, VCAM-1, and alphaEbeta7 in psoriatic lesions versus nonlesional skin. Finally, intra-epidermal CLA+ and alphaEbeta7+ T lymphocytes selectively expressed the chemokine receptor CXCR3. Collectively, these data suggest that CXCR3 and CCR4 may be involved in T lymphocyte trafficking to the psoriatic dermis and that CXCR3 is selectively involved in subsequent T cell homing to the overlying epidermis.

The expression of syndecan-1 is preferentially reduced compared with that of E-cadherin in acantholytic squamous cell carcinoma

BACKGROUND

Syndecan-1 and E-cadherin are cell adhesion molecules which are expressed primarily on the surface of adult epithelial cells. They appear to be co-regulated and may act in concert to stabilize the epithelium. Loss of expression of both E-cadherin and syndecan-1 is seen in malignant transformation and invasion.

METHODS

Thirteen cutaneous biopsies of acantholytic squamous cell carcinoma (SCC) were examined for coexpression of E-cadherin and syndecan-1.

RESULTS

Interestingly, immunoreactivity for E-cadherin was increased in the in situ component while immunoreactivity for syndecan-1 was similar to that seen in normal skin. Conversely, in invasive SCC the expression of these two adhesion molecules was very similar. Both diminished with decreasing cell differentiation, as well as in the acantholytic areas where both molecules exhibited increasing cytosolic staining rather than cell membrane staining.

CONCLUSIONS

Our results suggest that it is likely E-cadherin and syndecan-1 act in concert to stabilize the epithelium and that the loss or decreased expression of both of these adhesion molecules is associated with malignant transformation.

Distinct P-cadherin expression in cultured normal human keratinocytes and squamous cell carcinoma cell lines

Spatially regulated expression of E (epithelial)- and P (placental)-cadherins is crucial for maintaining normal epidermal architecture. In cutaneous squamous cell carcinomas (SCCs), aberrant P-cadherin expression is often observed in "squamoid" cancer cells, whereas E-cadherin expression in cancer cells is generally reduced. Therefore, it is plausible that SCC cells have acquired the ability to express P-cadherin and that P-cadherin plays a role in tumor progression. To address the issue, the in vitro effect of extracellular calcium on differentiation is a good model for investigating P-cadherin in normal and neoplastic skin. With elevations in extracellular calcium, human SCC cell line (DJM-1) cells initiate de novo synthesis of P-cadherin and express P-cadherin on the cell surface, whereas in normal human keratinocytes, P-cadherin expression on the cell surface is enhanced via the translocation from the cytosol to the cell membrane and/or the stabilization of P-cadherin at the cell surface. DJM-1 cells maintain P-cadherin expression on the cell surface at high levels for over 4 days after calcium elevation, whereas normal human keratinocytes cannot sustain cell surface P-cadherin when the cells are cultured in high calcium for more than 2 days. P-cadherin synthesis in DJM-1 cells is regulated at translational levels by extracellular calcium concentrations. SCC cells have the ability to produce P-cadherin by a mechanism not observed in normal keratinocytes, which might relate to the aberrant expression of P-cadherin in SCC of the skin.

Directed expression of keratin 16 to the progenitor basal cells of transgenic mouse skin delays skin maturation

We previously hypothesized that the type I keratin 16 (K16) plays a role in the process of keratinocyte activation that occurs in response to skin injury (Paladini, R.D., K. Takahashi, N.S. Bravo, and P.A. Coulombe. 1996. J. Cell Biol. 132:381-397). To further examine its properties in vivo, the human K16 cDNA was constitutively expressed in the progenitor basal layer of transgenic mouse skin using the K14 gene promoter. Mice that express approximately as much K16 protein as endogenous K14 display a dramatic postnatal phenotype that consists of skin that is hyperkeratotic, scaly, and essentially devoid of fur. Histologically, the epidermis is thickened because of hyperproliferation of transgenic basal cells, whereas the hair follicles are decreased in number, poorly developed, and hypoproliferative. Microscopically, the transgenic keratinocytes are hypertrophic and feature an altered keratin filament network and decreased cell-cell adhesion. The phenotype normalizes at approximately 5 wk after birth. In contrast, control mice expressing a K16-K14 chimeric protein to comparable levels are normal. The character and temporal evolution of the phenotype in the K16 transgenic mice are reminiscent of the activated EGF receptor- mediated signaling pathway in skin. In fact, tyrosine phosphorylation of the EGF receptor is increased in the newborn skin of K16 transgenic mice. We conclude that expression of K16 can significantly alter the response of skin keratinocytes to signaling cues, a distinctive property likely resulting from its unique COOH-terminal tail domain.

Expression of the anhidrotic ectodermal dysplasia gene is reduced in skin cancer coinciding with reduced E-cadherin

X-linked anhidrotic ectodermal dysplasia (EDA) is characterized by defects in the development of hair, teeth, and sweat glands. We have recently cloned the gene for EDA by positional cloning. The EDA gene encodes a transmembrane protein with a putative role in epithelial mesenchymal interactions. Since EDA could play a role in cell-cell or cell-matrix adhesion, acantholytic skin diseases and several types of non-invasive and invasive skin cancers were studied using in situ hybridization. Because of the observation that the promoter region of the EDA gene contains a binding site for LEF-1, which is involved in the signaling through E-cadherin/beta catenin complex, we compared the expression of EDA with immunolocalization for E-cadherin (E-CD). EDA expression during hair growth cycle, in benign adnexal tumors, and neuroectoderm-derived nevus cells was also examined. Our findings indicate that EDA expression is less abundant in malignant tumors, including basal and squamous cell carcinomas and melanoma, and in acantholytic keratinocytes compared to normal epidermis. The reduction in expression also coincides with diminished E-CD staining in all malignant cell types and in acantholytic cells. Our results suggest that EDA protein functions in the regulation of epithelial cell contacts and that it may be associated with the E-CD signaling pathway.

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

The Ca(2+)-dependent cell-cell adhesion molecules, termed cadherins, are subdivided into several subclasses. E (epithelial)- and P (placental)-cadherins are involved in the selective adhesion of epidermal cells. E-cadherin is expressed on the cell surfaces of all epidermal layers and P-cadherin is expressed only on the surfaces of basal cells. Ultrastructural studies have shown that E-cadherin is distributed on the plasma membranes of keratinocytes with a condensation in the intercellular space of the desmosomes. During human skin development P-cadherin expression is spatiotemporally controlled and closely related to the segregation of basal layers as well as to the arrangement of epidermal cells into eccrine ducts. In human skin diseases E-cadherin expression is markedly reduced on the acantholytic cells of tissues in pemphigus and Darier's disease. Cell adhesion molecules are now considered to play a significant role in the cellular connections of cancer and metastatic cells. Reduced expression of E-cadherin on invasive neoplastic cells has been demonstrated for cancers of the stomach, liver, breast, and several other organs. This reduced or unstable expression of E- and P-cadherin is observed in squamous cell carcinoma, malignant melanoma, and Paget's disease, but cadherin expression is conserved in basal cell carcinoma. Keratinocytes cultured in high calcium produce much more intense immunofluorescence of intercellular E- and P-cadherin than those cells grown in low calcium. E-cadherins on the plasma membrane of the keratinocytes are shifted to desmosomes under physiological conditions, and therein may express an adhesion function in association with other desmosomal cadherins. Soluble E-cadherins in sera are elevated in various skin diseases including bullous pemphigoid, pemphigus vulgaris, and psoriasis, but not in patients with burns. Markedly high levels in soluble E-cadherin are demonstrated in patients with metastatic cancers.

E- and P-cadherin expression in tumor tissues and soluble E-cadherin levels in sera of patients with skin cancer

The expression pattern of epithelial (E)- and placental (P)-calcium-dependent cell-cell adhesion molecules was examined immunohistochemically in various skin tumors. E- and P-cadherin expression was preserved in nodular and superficial types of basal cell carcinoma (BCC). In well-differentiated squamous cell carcinoma (SCC), E-cadherin on the cell surface of the tumor was reduced but expression of P-cadherin was preserved more frequently at the peripheral sites of the tumor than in the central sites of the tumor. Paget's cells and melanoma cells did not express E- or P-cadherins in the nest of the epidermis. Immunoreactive E-cadherin levels in sera were significantly elevated in patients with invasive Paget's disease, metastatic malignant melanoma and severe types of psoriasis and atopic dermatitis when compared with those of normal controls. Reduced or loss of cadherin in localized tumor cells may be correlated with the proliferation, and the level of soluble E-cadherin in circulation may be a marker in the extent of damaged skin by tumor and/or inflammation.