P-cadherin Expression Research Articles

P-cadherin controls the differentiation of oral keratinocytes by regulating cytokeratin 1/10 expression via C/EBP-beta-mediated signaling

P-cadherin belongs to the family of Ca2+-dependent homophilic glycosylated cell adhesion molecules. In the normal oral epithelium it shows a strong expression in the basal cell layer which gradually decreases in the suprabasal cell layers. The exact role of P-cadherin during the development and homeostasis of the oral epithelium has not been elucidated, yet. Here, we show for the first time that P-cadherin controls differentiation by regulating cytokeratin (CK) 1/10 expression in primary oral keratinocytes (POK) from normal, but interestingly not in POKs from oral squamous cell carcinoma (OSCC) tissue. SiRNA knockdown of P-cadherin in normal POKs revealed a strong upregulation of CK1/10 expression on mRNA and protein level. In contrast, E-cadherin knockdown in normal oral keratinocytes did not show any influence on CK1/10 expression. Moreover, in comparison with normal control keratinocytes normal oral keratinocytes with reduced P-cadherin expression displayed an enhanced expression and a stronger nuclear staining of C/EBP-beta, a well-known regulator of CK1/10 expression in keratinocytes. Furthermore, after P-cadherin knockdown in normal POKs the promoter activity of a C/EBP-responsive luciferase construct was significantly higher than in normal POKs with regular P-cadherin expression. Additionally, we noticed a proliferation advantage in normal oral keratinocytes in contrast to keratinocytes with diminished P-cadherin expression. However, the inverted effect was seen in tumor derived primary oral keratinocytes. In summary, we show that P-cadherin contributes to the keratinocyte differentiation in the oral epithelium by influencing the CK1 and CK10 expression via C/EBP-beta-mediated signaling in normal but not in tumor derived oral keratinocytes from OSCC patients.

Mimicking Hair Disorders by Genetic Manipulation of Organ-Cultured Human Hair Follicles

Human hair follicles can be dissected out of scalp skin and cultured in vitro in defined growth medium. Hair follicle organ cultures have previously been used to investigate the molecular and cellular mechanisms through which various factors regulate the maintenance and cycling of adult hair follicles. In this issue, Samuelov et al. transfected organ-cultured human hair follicles with siRNA nucleotides and suppressed the expression of the endogenous P-cadherin gene in follicular keratinocytes. Knocking down the expression of P-cadherin in hair follicles in vitro recapitulated the hair follicle phenotype observed in patients with hypotrichosis with juvenile macular dystrophy (HJMD) and enabled the authors to establish a cause-effect relationship between loss of P-cadherin and suppression of the canonical Wnt signaling pathway and upregulation of TGFβ2 during development of the hair abnormalities observed in HJMD patients.

Prognostic role of P-cadherin and periostin expression and nuclear morphometry in prostatic intraepithelial neoplasia and prostatic adenocarcinoma

Prognostic role of P-cadherin and periostin expression and nuclear morphometry in prostatic intraepithelial neoplasia and prostatic adenocarcinoma

P-cadherin as prognostic factor for loco-regional relapse in breast cancer.

Breast cancer is the most frequent malignant tumor and the leading cause of cancer death in women in Portugal. Due to its relation to an increase in distant metastasis and subsequent death, loco-regional relapse is one major concern in breast cancer women. Several classic prognostic factors as tumour size, nodal stage, histological grade, HER2 status and hormonal receptors have been identified as the most important factors for determining loco-regional relapse, disease free and overall survival. However, there is heterogeneity in prognosis and tumor behaviour in patients with identical disease staging and a similar pattern of expression of known molecular markers, hence the need to discover new prognostic factors. One of the possibilities is P-cadherin, already described by researchers as a possible independent marker of prognosis in breast cancer. The aim of this work was to study in a retrospective series of patients the correlation of P-cadherin expression with loco-regional recurrence in breast cancer women. We analyzed the clinical records of 1432 consecutive patients with breast cancer and treated in a University Hospital over a 10 year period. Patients with loco-regional relapse (n=101) without prior or simultaneous distant disease were selected as case group. Control group consisted of patients with more than 10 years follow-up and without disease progression. For both groups demographic, clinical, pathological and molecular markers were analyzed. Tissue micro-arrays were constructed to study P-cadherin expression from 86 tumors with available paraffin embedded blocks. Mean time to recurrence was 41 months and mean survival time after recurrence was 33 months, with a 5-year survival rate of 55%. Tumour size, nodal status and histological grade were identified as independent markers of prognosis. P-cadherin was associated with higher histological grades and hormone negative tumours. P-cadherin was identified as an independent prognostic marker for disease free survival, but not for overall survival. P-cadherin was related to other known factors of worse prognosis and had an independent relation to disease-free survival. P-cadherin might constitute a novel therapeutic target, but its real biological value is yet to be determined. Doubt persists whether it is an independent marker of tumour behaviour or only a surrogate marker of a set of clinical and molecular features related with worse prognosis.

P-cadherin is a direct PAX3–FOXO1A target involved in alveolar rhabdomyosarcoma aggressiveness

Alveolar rhabdomyosarcoma (ARMS) is an aggressive childhood cancer of striated muscle characterized by the presence of the PAX3-FOXO1A or PAX7-FOXO1A chimeric oncogenic transcription factor. Identification of their targets is essential for understanding ARMS pathogenesis. To this aim, we analyzed transcriptomic data from rhabdomyosarcoma samples and found that P-cadherin expression is correlated with PAX3/7-FOXO1A presence. We then show that expression of a PAX3 dominant negative variant inhibits P-cadherin expression in ARMS cells. Using mouse models carrying modified Pax3 alleles, we demonstrate that P-cadherin is expressed in the dermomyotome and lies genetically downstream from the myogenic factor Pax3. Moreover, in vitro gel shift analysis and chromatin immunoprecipitation indicate that the P-cadherin gene is a direct transcriptional target for PAX3/7-FOXO1A. Finally, P-cadherin expression in normal myoblasts inhibits myogenesis and induces myoblast transformation, migration and invasion. Conversely, P-cadherin downregulation by small hairpin RNA decreases the transformation, migration and invasive potential of ARMS cells. P-cadherin also favors cadherin switching, which is a hallmark of metastatic progression, by controlling N- and M-cadherin expression and/or localization. Our findings demonstrate that P-cadherin is a direct PAX3-FOXO1A transcriptional target involved in ARMS aggressiveness. Therefore, P-cadherin emerges as a new and attractive target for therapeutic intervention in ARMS.

P‐cadherin expression in Merkel cell carcinomas is associated with prolonged recurrence‐free survival

Merkel cell carcinoma (MCC) is a highly aggressive skin cancer, associated with advanced age, immunosuppression and Merkel cell polyomavirus (MCV) infections. As development and progression of cancer can be promoted by changes in cell adhesion proteins, we have previously analysed homo- and heterotypic cell-cell contacts of normal Merkel cells and MCCs and obtained indications for cadherin switching. To examine the prevalence and prognostic relevance of E-, N- and P-cadherin in MCCs. Paraffin-embedded MCC samples (n = 148) from 106 different patients were analysed by double-label immunostaining and immunofluorescence microscopy. MCV status was determined by real-time polymerase chain reaction. The cadherin repertoire and MCV status were correlated to clinical data, including tumour stage and recurrence-free survival. Ninety-one per cent of all MCC were positive for N-cadherin whereas only 61·6% and 70·3% expressed E- and P-cadherin, respectively. P-cadherin was significantly more frequent in primary tumours than in lymph node metastases (81·9% vs. 40·9%, P = 0·0002). Patients with P-cadherin-positive primary tumours were in earlier tumour stages at initial diagnosis (P = 0·0046). Both in log-rank tests (P = 0·0474) and in multiple Cox regression analysis including age, sex, immunosuppression, stage at initial diagnosis and MCV status (hazard ratio 0·193, P = 0·0373), patients with P-cadherin-positive primary MCCs had significantly prolonged recurrence-free survival (mean 25·2 vs. 10·6 months; median 9·0 vs. 4·0 months). MCV DNA was detected in 78·2% of all MCC, more frequently in P-cadherin-positive MCC (P = 0·0008). P-cadherin expression in MCCs predicts prolonged recurrence-free survival and may therefore indicate favourable prognosis.

P‐Cadherin Is Coexpressed with CD44 and CD49f and Mediates Stem Cell Properties in Basal‐like Breast Cancer

Although the luminal progenitor cell of the normal mammary gland hierarchy has been proposed as the cell-of-origin for basal-like breast cancers, finding the cancer stem cell (CSC) phenotype for this malignancy has proven a difficult task, mostly due to the lack of specific markers. Recently, basal-like sporadic and familial cases of breast cancer have been linked to BRCA1 gene inactivation, which enables the upregulation of the target-repressed CDH3/P-cadherin gene, an important biomarker of basal-like breast carcinomas. Previously, we demonstrated that P-cadherin overexpression can mediate aggressive behavior in these tumors. Thus, our aim was to test whether P-cadherin mediates stem cell properties in basal-like breast carcinomas. Using a series of breast cancer cell lines and primary tumors, we showed that P-cadherin was directly associated with the expression of the breast stem markers CD44, CD49f, and aldehyde dehydrogenase 1 in the basal subtype. Moreover, cell population enriched for P-cadherin expression comprised increased in vitro mammosphere-forming efficiency and capacity to grow colonies in three-dimensional cultures as well as greater tumorigenicity. Importantly, an association was found with stem-/progenitor-like phenotypes of the breast, including the luminal progenitor population, CD49f(+) CD24(+). Additionally, P-cadherin expression conferred resistance to x-ray-induced cell death, sustaining a role for this molecule in another stem cell property. In summary, we demonstrated, for the first time, that P-cadherin mediates stem cell properties, which could be explored in order to better define the CSC phenotype of basal-like breast tumors and the cell-of-origin of this malignancy.

P-cadherin expression and basal-like subtype in breast cancers

Breast cancer is considered as one of the multifactorial diseases. The aim of the current study is to investigate the association between P-cadherin and molecular subtypes of breast cancer, especially the basal-like subtype. Two hundred and thirteen breast-invasive ductal carcinomas were involved in this study. The expressions of P-cadherin were detected via immunohistochemistry. The 213 cases were divided into luminal A, luminal B, HER2 overexpression subtype, and normal breast-like and basal-like subtypes according to the standard of molecular breast cancer subtypes. In addition, the expressions of CK5/6 and CK14 were detected to distinguish between the normal breast-like and the basal-like subtypes. P-cadherin expression was found in 91 cases of 213 breast-invasive ductal carcinomas, with a positive rate of 42.7%. P-cadherin correlated negatively with estrogen receptor (ER) (p=0.001) and progesterone receptor (p=0.001), whereas it positively correlated with histologic grade (p=0.003), NPI (p=0.005), p53 (p=0.038), and Ki67 (p=0.022). P-cadherin expression showed a strong correlation with recurrence and distant metastasis (p=0.009), and invasion of the vascular and soft tissues (p=0.004). Moreover, P-cadherin expression existed in the basal-like and non-basal-like subtypes. During prognosis, P-cadherin expression was associated with decreased disease-free survival in patients (p=0.009) and overall survival (OS) (p=0.005). In addition, multivariate analysis showed that tumor grade (p=0.021), ER (p=0.015), clinical stage (p=0.001), and P-cadherin (p=0.033) were significant predictors of OS. The current data suggest that P-cadherin may be used to distinguish the basal-like subtype and to predict the outcome in view of the relationship with DFS and OS. Furthermore, P-cadherin expression may be useful in making treatment decisions.

The adult retinal stem cell is a rare cell in the ciliary epithelium whose progeny can differentiate into photoreceptors

SummarySelf-renewing, multipotential retinal stem cells (RSCs) reside in the pigmented ciliary epithelium of the peripheral retina in adult mammals. RSCs can give rise to rhodopsin positive-cells, which can integrate into early postnatal retina, and represent a potentially useful option for cellular therapy. The ability to purify a stem cell population and direct the differentiation toward a particular cell lineage is a challenge facing the application of stem cells in regenerative medicine. Here we use cell sorting to prospectively enrich mouse RSCs based on size, granularity and low expression of P-cadherin and demonstrate that only rare cells with defined properties proliferate to form colonies. We show that clonally-derived mouse and human RSC progeny are multipotent and can differentiate into mature rhodopsin-positive cells with high efficiency using combinations of exogenous culture additives known to influence neural retinal development, including taurine and retinoic acid. This directed RSC differentiation follows the temporal sequence of photoreceptor differentiation in vivo, and the cells exhibit morphology, protein and gene expression consistent with primary cultures of rods in vitro. These results demonstrate that the RSC, an adult stem cell, can be enriched and directed to produce photoreceptors as a first step toward a targeted cell replacement strategy to treat retinal degenerative disease.

High-risk human papillomavirus infections in colorectal cancer in the Syrian population and their association with Fascin, Id-1 and P-cadherin expressions: A tissue microarray study

Background: High-risk human papillomaviruses (HPVs) can be regarded as important risk factors for colorectal carcinogenesis and metastasis. Alternatively, earlier studies have reported that Fascin, Id-1 and P-cadherin genes are important regulators of cell invasion and metastasis in several human carcinomas, including colorectal. In order to investigate the correlation between the presence of high-risk HPVs and Fascin, Id-1, and P-cadherin genes in human colorectal cancer (CRC) in the Syrian population, we examined the incidence of high-risk HPV types (16, 18, 31, 33 and 35) and their association with Fascin, Id-1 and P-cadherin expression. Materials and Methods: A total of 78 blocks from CRC Syrian patients were used in this study. These blocks were analyzed using polymerase chain reaction (PCR) and tissue microarray (TMA) analyses for the presence of high-risk HPVs and Fascin, Id-1 as well as P-cadherin expression, respectively. Results: We found that high-risk HPVs were present in 42 samples (53.84%), which represent the majority of invasive CRC cases; the most frequent high-risk HPV types in the Syrian population are 16, 33, 18, 35 and 31 respectively. Furthermore, the expression of E6 onco-protein of high-risk HPVs was found to be correlated with Fascin, Id-1 and P-cadherin expression/over-expression in the majority of CRC tissue samples. Conclusion : These data reveal that high-risk HPVs are present in human CRCs in the Syrian population, and their presence is associated with invasive and metastatic phenotype.

P-Cadherin Expression in Feline Mammary Tissues

The search for molecular markers in the feline mammary gland, namely, the adhesion molecules belonging to the cadherin family, is useful in the understanding of the development of mammary carcinomas in felines and humans. To study P-cadherin expression in the feline mammary gland, 61 samples of normal (n = 4), hyperplastic (n = 12), and neoplastic (n = 45) feline mammary tissues were examined. In both normal and hyperplastic mammary tissues as well as in benign tumours, P-cadherin immunolabelling was restricted to myoepithelial cells. In malignant tumours, however, there was an aberrant epithelial P-cadherin immunoexpression in 64.1% (n = 25) of cases, with a membranous and/or cytoplasmic pattern of distribution. A statistically significant relationship was seen between epithelial P-cadherin expression and malignant mammary lesions (P = 0.0001). In malignant mammary tumours, there was likewise a statistically significant relationship between aberrant P-cadherin immunoexpression and histological grade (P = 0.0132). Aberrant epithelial P-cadherin expression seems to be related to malignancy in the feline mammary gland. To confirm the results of this investigation, further studies with larger samples and follow-up studies are warranted.

Mesangial Medium from IgA Nephropathy Patients Induces Podocyte Epithelial-to-mesenchymal Transition through Activation of the Phosphatidyl Inositol-3-kinase/Akt Signaling Pathway

Background: Podocyte injury plays an important role in glomerulosclerosis in IgA nephropathy (IgAN). Eepithelial-to-mesenchymal transition (EMT) caused by different factors is the main reason for podocyte damage. This study hypothesized that conditioned mesangial medium may induced EMT process of podocytes and thereby lead to glomerular injury or sclerosis. Materials and Methods: Podocytes were incubated in medium from mesangial cells incubated with aggregated IgA1(aIgA1) isolated from IgAN patients. Wortmannin were used to inhibit phosphatidylinositol-3-kinase (PI3-K) in podocytes. Results: Western blot analysis, real-time PCR and confocal fluorescent microscopy demonstrated that reduced expression of P-Cadherin, Zonula occludens-1 (ZO-1) and podocin, increased expression of fibroblast –specific protein (FSP-1), α-smooth muscle action(α-SMA) and desmin in podocytes exposed to medium from mesangial cells incubated with aIgA1 isolated from IgAN patients compared with podocytes cultured in RPMI 1640 medium containing 0.5% fetal bovine serum ( FBS) (p<0.05). Mesangial medium resulted in a greater albumin influx across the podocyte monolayer (p<0.05). Phosphorylation of Akt increased with this medium, as indicated by an increase in the p-Akt/Akt ratio. Treatment with wortmannin partly restored the changes in epithelial and mesenchymal markers and albumin influx. IgAN patients with massive proteinuria showed remarkable α-SMA and FSP-1 expression in podocytes. Conclusion: Our findings indicated that mesangial medium from cells incubated with aIgA1 isolated from IgAN patients induced EMT in podocytes and the PI3-K/ Akt-signaling pathway was involved in the process.

Podocyte Wnt/ß-catenin pathway is activated by integrin-linked kinase in clinical and experimental focal segmental glomerulosclerosis

Changes in podocyte phenotype and function are characteristic of proteinuric glomerular diseases. Integrin-linked kinase (ILK) functions as a common downstream effector in proteinuric diseases. In addition, ILK was shown to interact with the Wnt signaling pathway. Here, we investigated ILK expression as well as its involvement with the Wnt signaling pathway in renal biopsies of patients with primary focal segmental glomerulosclerosis (FSGS), and in a correspondent in vivo model of podocyte lesion. Biopsies from 37 patients with primary FSGS were evaluated by immunohistochemistry for ILK, phosphorylated GSK-3ß (pGSK-3ß) and ß-catenin expression. As experimental model, male Wistar rats received 5 injections of puromycin aminonucleoside (PAN) at 2-week intervals, and their kidneys were evaluated for ILK, P-cadherin and pAkt expression as well as ß-catenin and LEF-1 colocalization. Patients presented de novo ILK expression and pGSK-3ß in podocytes. In animals, there was an increase in gene and protein expression of ILK, mainly detected in the podocytes, as well as increased protein expression of pAkt compared with controls. ß-Catenin translocated to the nuclei of podocytes in animals and patients. ß-Catenin colocalized with LEF-1 in the nuclei of podocytes of animals. Gene expression of ß-catenin and P-cadherin in PAN rats was lower compared with controls. Our findings suggest that activation of ILK activated the Wnt signaling pathway in damaged podocytes. This phenomenon could have an important role in development and/or progression of clinical and experimental FSGS.

Epithelial-to-mesenchymal transition in podocytes mediated by activation of NADPH oxidase in hyperhomocysteinemia

The present study tested the hypothesis that hyperhomocysteinemia (hHcys) induces podocytes to undergo epithelial-to-mesenchymal transition (EMT) through the activation of NADPH oxidase (Nox). It was found that increased homocysteine (Hcys) level suppressed the expression of slit diaphragm-associated proteins, P-cadherin and zonula occludens-1 (ZO-1), in conditionally immortalized mouse podocytes, indicating the loss of their epithelial features. Meanwhile, Hcys remarkably increased the abundance of mesenchymal markers, such as fibroblast specific protein-1 (FSP-1) and α-smooth muscle actin (α-SMA). These phenotype changes in podocytes induced by Hcys were accompanied by enhanced superoxide (O⁻₂) production, which was substantially suppressed by inhibition of Nox activity. Functionally, Hcys significantly enhanced the permeability of the podocyte monolayer coupled with increased EMT, and this EMT-related increase in cell permeability could be restored by Nox inhibitors. In mice lacking gp91( phox ) (gp91(-/-)), an essential Nox subunit gene, hHcys-enhanced podocyte EMT and consequent glomerular injury were examined. In wild-type (gp91(+/+)) mice, hHcys induced by a folate-free diet markedly enhanced expression of mesenchymal markers (FSP-1 and α-SMA) but decreased expression of epithelial markers of podocytes in glomeruli, which were not observed in gp91(-/-) mouse glomeruli. Podocyte injury, glomerular sclerotic pathology, and marked albuminuria observed in gp91(+/+) mice with hHcys were all significantly attenuated in gp91(-/-) mice. These results suggest that hHcys induces EMT of podocytes through activation of Nox, which represents a novel mechanism of hHcys-associated podocyte injury.

P-Cadherin Promotes Liver Metastasis and Is Associated with Poor Prognosis in Colon Cancer

P-cadherin belongs to the family of classic cadherins, which is important for maintaining cellular localization and tissue integrity. Recently, it has become evident that P-cadherin contributes to the oncogenesis of many tumor types, including melanoma, prostate, breast, and colon carcinomas. Although cadherin switching is a crucial step in metastasis, the role of P-cadherin in colon cancer metastasis to the liver is unknown. In this study, we performed gene expression analysis and found that the level of P-cadherin was higher in tissue from liver metastases of colon cancer than in the corresponding primary colon cancer tissues. IHC analysis also showed that P-cadherin expression was significantly higher in liver metastases than in paired primary colorectal cancer tumors. Knockdown of P-cadherin in colon cancer cells inhibited wound healing, proliferation, and colony formation and resulted in developing fewer liver metastatic foci and reducing the tumor burden in vivo. Inhibition of P-cadherin expression also induced the up-regulation of E-cadherin and the down-regulation of β-catenin and its downstream target molecules, including survivin and c-Myc. In summary, these results uncover a novel function of P-cadherin in the regulation of colon cancer metastasis to the liver, suggesting that blocking the activity of P-cadherin or its associated signaling may be a valuable target for the treatment of hepatic metastases of colon carcinomas.

P-cadherin expression reduces melanoma growth, invasion, and responsiveness to growth factors in nude mice

The prognostic discrepancy between localized melanoma and metastatic disease demands a better understanding of melanoma progression. The role of E-cadherin and N-cadherin in melanoma has been widely studied; however, the function of P-cadherin remains to be elucidated. We wanted to assess the effects of P-cadherin overexpression in BLM melanoma cells with regard to xenograft growth, invasion, and survival of mice in our model to mimic micrometastatic spread. Swiss nu/nu mice were subcutaneously injected with control (BLM LIE) and P-cadherin overexpressing (BLM P-cad) melanoma cells alone and in combination with myofibroblasts, and intracardially injected with BLM LIE and BLM P-cad cells. Tumor volumes and survival of mice were assessed and analyzed. In-vitro assays were used to further investigate the influence, and identify the target receptors of growth factors secreted by myofibroblasts in melanoma cells. In-vivo experiments point out that P-cadherin reduces xenograft growth (1621 mm ± 107 vs. 329 mm ± 71) and invasion, and prolongs overall survival (34.1 ± 0.84 vs. 51.1 ± 1.8 days) of mice in our model to mimic micrometastatic spread. Coinjection with myofibroblasts resulted in increased tumor growth in BLM LIE (3896 mm ± 64 vs. 1621 mm ± 107) in contrast to BLM P-cad (417 mm ± 47 vs. 329 ± 71). P-cadherin reduces melanoma growth and invasion, prolongs the survival of mice intracardially injected, and induces a state of decreased responsiveness to myofibroblast-derived growth factors. Therefore, P-cadherin can be considered as a potential therapeutic target in the treatment of melanoma.

The cadherin switch in ovarian high-grade serous carcinoma is associated with disease progression

Ovarian high-grade serous carcinoma (HGSC) often has a poor prognosis because of late presentation, lack of sensitivity and specificity of screening modalities and the development of chemoresistance. New targeted therapy is required if survival in these cases is to improve. The profile of E-, P- and N-cadherins in ovarian cancer and its association with survival remain poorly understood. Reduced expression of E-cadherin in prostate cancer associated with increase in the expression of N- and P-cadherins is described as cadherin switch. We hypothesised that there is a switch in the expression of cadherins that regulates the behaviour of HGSC and possibly its outcome. To identify the stages of the cadherin switch in HGSC, we studied the immunoexpression of E-, P- and N-cadherins in a cohort of 177 cases of HGSC. High expression of P-cadherin was associated with poor patient survival and was significantly higher in stage 2 disease when compared with stage 1 and stage 3 disease (P = 0.033). In contrast, loss of E-cadherin was observed in stage 3 HGSC when compared with other stages (P = 0.050). E-, P- and N- cadherin expressions were significantly associated with disease outcome when assessed individually and in various combinations with an interesting profile. Our results indicate that the cadherin switch alters through progression of HGSC. The profile of combined cadherin expressions in association with survival raises expectations in targeted therapy.

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.

Slit-2 facilitates interaction of P-cadherin with Robo-3 and inhibits cell migration in an oral squamous cell carcinoma cell line

Slits are a group of secreted glycoproteins that act as molecular guidance cues in cellular migration. Recently, several studies demonstrated that Slit-2 can operate as candidate tumour suppressor protein in various tissues. In this study, we show Slit-2 expression in basal cell layers of normal oral mucosa colocalized with P-cadherin expression. In contrast, there is a loss of Slit-2 and P-cadherin expression in mucosa of oral squamous cell carcinoma (OSCC). Our in vitro investigations reveal a correlation of P-cadherin and Slit-2 expression: OSCC cells with induced P-cadherin expression (PCI52_PC) display an increased Slit-2 expression. However, abrogating P-cadherin function with a function-blocking antibody decreases Slit-2 secretion confirming a direct link between P-cadherin and Slit-2. Moreover, experiments with OSCC cells show that Slit-2 interferes with a Wnt related signalling pathway, which in turn affects Slit-2 expression in a feedback loop. Functionally, transwell migration assays demonstrate a Slit-2 dose-dependent decrease of PCI52_PC cell migration. However, there is no influence on migration in mock control cells. Responsible for this migration block might be an interaction of P-cadherin with Roundabout (Robo)-3, a high affinity receptor of Slit-2. Indeed, proximity ligation assays exhibit P-cadherin/Robo-3 interactions on PCI52_PC cells. Additionally, we detect a modulation of this interaction by addition of recombinant Slit-2. Down-regulation of Robo-3 expression via small interfering RNA neutralizes Slit-2 induced migration block in PCI52_PC cells. In summary, our experiments show antitumorigenic effects of Slit-2 on P-cadherin expressing OSCC cells supposedly via modulation of Robo-3 interaction.

P-cadherin cooperates with insulin-like growth factor-1 receptor to promote metastatic signaling of gonadotropin-releasing hormone in ovarian cancer via p120 catenin

Gonadotropin-releasing hormone (GnRH) is a potent prometastatic factor in ovarian cancer, but the intracellular signaling events are not well understood. The classical Gα(q)-phospholipase C signal transduction pathway known to operate in the pituitary is not involved in GnRH actions at non-pituitary targets. Here we showed that GnRH treatment of ovarian cancer cells led to a rapid and remarkable tyrosine phosphorylation of p120 catenin (p120(ctn)), which was mediated by P-cadherin. The use of P-cadherin small interfering RNA or neutralizing antibodies to inhibit P-cadherin expression and function resulted in diminished p120(ctn) activation, confirming that the effect was P-cadherin specific. On exploring how P-cadherin, which lacks intrinsic kinase activity, might regulate the activation of p120(ctn), we found that P-cadherin could induce the ligand-independent activation of insulin-like growth factor-1 receptor (IGF-1R). Inhibition of IGF-1R expression or its activity significantly inhibited GnRH-induced p120(ctn) activation, and the subsequent cell migration and invasion. In addition, we showed that IGF-1R regulation by P-cadherin was associated with complex formation between IGF-1R and P-cadherin, and this regulation was also observed to be in vivo correlated with metastasis. Furthermore, using a mouse model of ovarian cancer metastasis, GnRH receptor knockdown was shown to diminish peritoneal dissemination of tumors and ascites formation. These findings suggest for the first time that GnRH can initiate an outside-in p120(ctn) signal transduction through the cross-talk between P-cadherin and IGF-1R, thus providing a novel molecular mechanism by which GnRH may control the high level of aggressiveness and invasion and metastasis potential that are characteristic of ovarian cancer.