P-cadherin promotes cell-cell adhesion and counteracts invasion in human melanoma

Mechanisms and Therapeutic Strategies for Minority Cell-Induced Paclitaxel Resistance and Tumor Progression Mediated by Mechanical Forces

Chemotherapy remains a prevalent strategy in cancer therapy; however, the emergence of drug resistance poses a considerable challenge to its efficacy. Most drug resistance arises from the accumulation of genetic mutations in a minority of resistant cells. The mechanisms underlying the emergence and progression of cancer resistance from these minority-resistant cells (MRCs) remain poorly understood. This study employs force-induced remnant magnetization spectroscopy (FIRMS) alongside various biological investigations to reveal the mechanical pathways for MRCs fostering drug resistance and tumor progression. The findings show that minority Paclitaxel-resistant cancer cells have enhanced mechanical properties. These cells can transmit high-intensity forces to surrounding sensitive cells (SCs) through the force transducer, Merlin. This force transmission facilitates the assimilation of surrounding SCs, subsequently strengthening the contraction and adhesion of tumor cells. This process is termed "mechano-assimilation," which accelerates the development of drug resistance and tumor progression. Interestingly, disturbances and reductions of mechano-assimilation within tumors can restore sensitivity to Paclitaxel both in vitro and in vivo. This study provides preliminary evidence highlighting the contribution of MRCs to the development of drug resistance and malignancy, mediated through mechanical interactions. It also establishes a foundation for future research focused on integrating mechanical factors into innovative cancer therapies.

Dynamic changes in the skin transcriptome for the melanin pigmentation in embryonic chickens

Dermal hyperpigmentation stands out among the various skin pigmentation phenotypes in chickens, where most other pigmentation variants affect feather color and patterning predominantly. Despite numerous black chicken breeds worldwide, only a select few exhibit comprehensive black pigmentation, which encompasses the skin, meat, flesh, and bones. The process of skin melanin pigmentation is intricate and develops successively. Historically, research has concentrated primarily on specific developmental points or stages, but fewer studies have examined the entire transcriptome across the timeline of the development of the embryo integument. In our investigation, we undertook the sequencing of chicken embryo skin samples from d 4 to d 13 of incubation. Our results showed that melanoblasts continued to migrate from E4 to the epidermis until E12. Beginning with E6, melanin was synthesized and transferred to epidermal cells and feather follicles in large quantities, and genes such as DCT, TYR, TYRP1, and MITF played a key role in this process, which is significantly different from that of white-skinned chickens. There were 854 differentially expressed genes between E7 and E8. At this stage, melanocytes formed dendritic forms and transferred melanin to keratinocytes, while the dorsal skin became visibly dark. In addition, CDH3, which is a core factor involved in a variety of biological processes, may have an important impact on skin melanin pigmentation. Collectively, our findings unveiled a phased relationship between the canonical pathway and the noncanonical pathway from E4 to E13. These analyses illuminated the gene regulatory mechanism and provided foundational data that pertained to pigmentation in chickens.

CDH3-AS1 antisense RNA enhances P-cadherin translation and acts as a tumor suppressor in melanoma

Thousands of regulatory noncoding RNAs (ncRNAs) have been annotated; however, their functions in gene regulation and contributions to cancer formation remain poorly understood. To gain a better understanding of the influence of ncRNAs on gene regulation during melanoma progression, we mapped the landscape of ncRNAs in melanocytes and melanoma cells. Nearly half of deregulated genes in melanoma are ncRNAs, with antisense RNAs (asRNAs) comprising a large portion of deregulated ncRNAs. CDH3-AS1, the most significantly downregulated asRNA, overlaps the CDH3 gene, which encodes P-cadherin, a transmembrane glycoprotein involved in cell adhesion that was also reduced in melanoma. Overexpression of CDH3-AS1 increased cell aggregation and reduced xenograft tumor growth, mimicking the tumor-suppressive effects of CDH3. CDH3-AS1 interacted with CDH3 mRNA and enhanced P-cadherin protein levels. Interestingly, secondary structures at the CDH3 5' end regulated P-cadherin translation, and ribosome profiling revealed that CDH3-AS1 promotes ribosome occupancy at the CDH3 mRNA. Notably, ribosome occupancy was generally increased in mRNAs having cognate asRNA that are complementary to the 5'UTR. Taken together, this study revealed the CDH3-AS1-mediated enhancement of P-cadherin translation, underscoring the broader potential of asRNAs as regulators of protein-coding genes and their role in diseases like melanoma.

PCDH9 suppresses melanoma proliferation and cell migration

BACKGROUND

Melanoma has dramatically increased during last 30 years with low 5-year survival and prognosis rate.

METHODS

Melanoma cells (A375 and G361) were chosen as the in vitro model. The immunohistochemical (IHC) analysis and bioinformatics mining exhibited the suppression of PCDH9 on melanoma. The interference and overexpression of PCDH9 were infected by lentivirus. The effects of PCDH9 on melanoma cells were assessed in terms of alteration of PCDH9 such as cell viability, apoptosis, cell cycle, and wound-healing assay. Moreover, expressions of PCDH9 with other genes (MMP2, MMP9, CCND1, and RAC1) were also assessed by PCR.

RESULTS

The alteration of PCDH9 has a negative correlation with MMP2, MMP9, and RAC1 but had a positive correlation with CCND1 (Cyclin D1) and apoptosis. Increase of PCDH9 could suppress melanoma cells and inhibit migration but not exert significant effects on cell cycle. IHC showed lower PCDH9 expression in melanoma tissue with main expression in cytoplasm.

CONCLUSION

Overexpressed PCDH9 suppressed melanoma cells, and PCDH9 can be considered as an independent prognostic factor for melanoma; even re-expression of PCDH9 can serve as a potential therapeutic strategy for melanoma treatment.

Epithelial–mesenchymal transition: The history, regulatory mechanism, and cancer therapeutic opportunities

Epithelial–mesenchymal transition (EMT) is a program wherein epithelial cells lose their junctions and polarity while acquiring mesenchymal properties and invasive ability. Originally defined as an embryogenesis event, EMT has been recognized as a crucial process in tumor progression. During EMT, cell–cell junctions and cell–matrix attachments are disrupted, and the cytoskeleton is remodeled to enhance mobility of cells. This transition of phenotype is largely driven by a group of key transcription factors, typically Snail, Twist, and ZEB, through epigenetic repression of epithelial markers, transcriptional activation of matrix metalloproteinases, and reorganization of cytoskeleton. Mechanistically, EMT is orchestrated by multiple pathways, especially those involved in embryogenesis such as TGFβ, Wnt, Hedgehog, and Hippo, suggesting EMT as an intrinsic link between embryonic development and cancer progression. In addition, redox signaling has also emerged as critical EMT modulator. EMT confers cancer cells with increased metastatic potential and drug resistant capacity, which accounts for tumor recurrence in most clinic cases. Thus, targeting EMT can be a therapeutic option providing a chance of cure for cancer patients. Here, we introduce a brief history of EMT and summarize recent advances in understanding EMT mechanisms, as well as highlighting the therapeutic opportunities by targeting EMT in cancer treatment.

P-Cadherin Regulates Intestinal Epithelial Cell Migration and Mucosal Repair, but Is Dispensable for Colitis Associated Colon Cancer

Recurrent chronic mucosal inflammation, a characteristic of inflammatory bowel diseases (IBD), perturbs the intestinal epithelial homeostasis resulting in formation of mucosal wounds and, in most severe cases, leads to colitis-associated colon cancer (CAC). The altered structure of epithelial cell-cell adhesions is a hallmark of intestinal inflammation contributing to epithelial injury, repair, and tumorigenesis. P-cadherin is an important adhesion protein, poorly expressed in normal intestinal epithelial cells (IEC) but upregulated in inflamed and injured mucosa. The goal of this study was to investigate the roles of P-cadherin in regulating intestinal inflammation and CAC. P-cadherin expression was markedly induced in the colonic epithelium of human IBD patients and CAC tissues. The roles of P-cadherin were investigated in P-cadherin null mice using dextran sulfate sodium (DSS)-induced colitis and an azoxymethane (AOM)/DSS induced CAC. Although P-cadherin knockout did not affect the severity of acute DSS colitis, P-cadherin null mice exhibited faster recovery after colitis. No significant differences in the number of colonic tumors were observed in P-cadherin null and control mice. Consistently, the CRISPR/Cas9-mediated knockout of P-cadherin in human IEC accelerated epithelial wound healing without affecting cell proliferation. The accelerated migration of P-cadherin depleted IEC was driven by activation of Src kinases, Rac1 GTPase and myosin II motors and was accompanied by transcriptional reprogramming of the cells. Our findings highlight P-cadherin as a negative regulator of IEC motility in vitro and mucosal repair in vivo. In contrast, this protein is dispensable for IEC proliferation and CAC development.

The Development of Peritoneal Metastasis from Gastric Cancer and Rationale of Treatment According to the Mechanism

In the present article, we describe the normal structure of the peritoneum and review the mechanisms of peritoneal metastasis (PM) from gastric cancer (GC). The structure of the peritoneum was studied by a double-enzyme staining method using alkaline-phosphatase and 5'-nucreotidase, scanning electron microscopy, and immunohistological methods. The fundamental structure consists of three layers, mesothelial cells and a basement membrane (layer 1), macula cribriformis (MC) (layer 2), and submesothelial connective tissue containing blood vessels and initial lymphatic vessels, attached to holes in the MC (layer 3). Macro molecules and macrophages migrate from mesothelial stomata to the initial lymphatic vessels through holes in the MC. These structures are characteristically found in the diaphragm, omentum, paracolic gutter, pelvic peritoneum, and falciform ligament. The first step of PM is spillage of cancer cells (peritoneal free cancer cells; PFCCs) into the peritoneal cavity from the serosal surface of the primary tumor or cancer cell contamination from lymphatic and blood vessels torn during surgical procedures. After PFCCs adhere to the peritoneal surface, PMs form by three processes, i.e., (1) trans-mesothelial metastasis, (2) trans-lymphatic metastasis, and (3) superficial growing metastasis. Because the intraperitoneal (IP) dose intensity is significantly higher when generated by IP chemotherapy than by systemic chemotherapy, IP chemotherapy has a great role in the treatment of PFCCs, superficial growing metastasis, trans-lymphatic metastasis and in the early stages of trans-mesothelial metastasis. However, an established trans-mesothelial metastasis has its own interstitial tissue and vasculature which generate high interstitial pressure. Accordingly, it is reasonable to treat established trans-mesothelial metastasis by bidirectional chemotherapy from both IP and systemic chemotherapy.

Signal pathways of melanoma and targeted therapy

Melanoma is the most lethal skin cancer that originates from the malignant transformation of melanocytes. Although melanoma has long been regarded as a cancerous malignancy with few therapeutic options, increased biological understanding and unprecedented innovations in therapies targeting mutated driver genes and immune checkpoints have substantially improved the prognosis of patients. However, the low response rate and inevitable occurrence of resistance to currently available targeted therapies have posed the obstacle in the path of melanoma management to obtain further amelioration. Therefore, it is necessary to understand the mechanisms underlying melanoma pathogenesis more comprehensively, which might lead to more substantial progress in therapeutic approaches and expand clinical options for melanoma therapy. In this review, we firstly make a brief introduction to melanoma epidemiology, clinical subtypes, risk factors, and current therapies. Then, the signal pathways orchestrating melanoma pathogenesis, including genetic mutations, key transcriptional regulators, epigenetic dysregulations, metabolic reprogramming, crucial metastasis-related signals, tumor-promoting inflammatory pathways, and pro-angiogenic factors, have been systemically reviewed and discussed. Subsequently, we outline current progresses in therapies targeting mutated driver genes and immune checkpoints, as well as the mechanisms underlying the treatment resistance. Finally, the prospects and challenges in the development of melanoma therapy, especially immunotherapy and related ongoing clinical trials, are summarized and discussed.

Cadherin‐3 is a novel oncogenic biomarker with prognostic value in glioblastoma

Glioblastoma (GBM) is the most common and malignant primary brain tumor in adults. The prognosis of patients is very poor, with a median overall survival of ~ 15 months after diagnosis. Cadherin‐3 (also known as P‐cadherin), a cell–cell adhesion molecule encoded by the CDH3 gene, is deregulated in several cancer types, but its relevance in GBM is unknown. In this study, we investigated the functional roles, the associated molecular signatures, and the prognostic value of CDH3/P‐cadherin in this highly malignant brain tumor. CDH3/P‐cadherin mRNA and protein levels were evaluated in human glioma samples. Knockdown and overexpression models of P‐cadherin in GBM were used to evaluate its functional role in vitro and in vivo. CDH3‐associated gene signatures were identified by enrichment analyses and correlations. The impact of CDH3 in the survival of GBM patients was assessed in independent cohorts using both univariable and multivariable models. We found that P‐cadherin protein is expressed in a subset of gliomas, with an increased percentage of positive samples in grade IV tumors. Concordantly, CDH3 mRNA levels in glioma samples from The Cancer Genome Atlas (TCGA) database are increased in high‐grade gliomas. P‐cadherin displays oncogenic functions in multiple knockdown and overexpression GBM cell models by affecting cell viability, cell cycle, cell invasion, migration, and neurosphere formation capacity. Genes that were positively correlated with CDH3 are enriched for oncogenic pathways commonly activated in GBM. In vivo, GBM cells expressing high levels of P‐cadherin generate larger subcutaneous tumors and cause shorter survival of mice in an orthotopic intracranial model. Concomitantly, high CDH3 expression is predictive of shorter overall survival of GBM patients in independent cohorts. Together, our results show that CDH3/P‐cadherin expression is associated with aggressiveness features of GBM and poor patient prognosis, suggesting that it may be a novel therapeutic target for this deadly brain tumor.

Placental-Cadherin, a biomarker for local immune status and poor prognosis among patients with tongue squamous cell carcinoma

BACKGROUND

The prognostic and clinicopathological value of placental-Cadherin (CDH3) in multiple cancers is controversial. The diagnostic significance and functional mechanism of CDH3 in tongue squamous cell carcinoma (TSCC) have not been thoroughly investigated. This study aims to clarify the potential of CDH3 as biomarker for TSCC.

METHODS

Here, meta-analysis, bioinformatics, along wet-lab techniques were employed to evaluate the diagnostic, as well as the prognostic value of CDH3 in diverse types of cancers, especially TSCC. Meta-analysis was used to determine the influence of CDH3 on prognostic and clinicopathological features in numerous cancers. Molecular biology function was used to investigate the role of CDH3 in TSCC cells. The relationship of CDH3 with tumor-infiltrating immune cells (TIICs) in TSCC was assessed using CIBERSORT. Moreover, gene set enrichment analysis (GSEA) was done based on TCGA. Besides, the hub genes and associated cascades were uncovered based on gene co-expression with CDH3.

RESULTS

CDH3 upregulation correlated with worse overall survival and disease-free survival in various cancers. CDH3 was validated as an independent risk factor for HNSC and was linked to the onset of tumors, tumor stage, and infiltration depth. CDH3 silencing inhibited cell growth and induced apoptosis of the CAL-27 cell line. CDH3 expression level correlated with infiltration by macrophages, T cells, T cell regulatory cells (Tregs), and plasma cells in TSCC. GSEA revealed that CDH3 influences multiple cancer-associated cascades. Besides, CBX3, CCHCR1, along NFYC were identified as the core hub genes for CDH3.

CONCLUSION

We identified CDH3 as a pan-cancer gene with potential prognostic and diagnostic significance in various cancers, particularly in TSCC, where it is tumorigenic.

Cell Adhesion Molecules in Plasticity and Metastasis

Prior to metastasis, modern therapeutics and surgical intervention can provide a favorable long-term survival for patients diagnosed with many types of cancers. However, prognosis is poor for patients with metastasized disease. Melanoma is the deadliest form of skin cancer, yet in situ and localized, thin melanomas can be biopsied with little to no postsurgical follow-up. However, patients with metastatic melanoma require significant clinical involvement and have a 5-year survival of only 34% to 52%, largely dependent on the site of colonization. Melanoma metastasis is a multi-step process requiring dynamic changes in cell surface proteins regulating adhesiveness to the extracellular matrix (ECM), stroma, and other cancer cells in varied tumor microenvironments. Here we will highlight recent literature to underscore how cell adhesion molecules (CAM) contribute to melanoma disease progression and metastasis.

Aberrant Expression of E-cadherin, N-cadherin, and P-cadherin in Clear Cell Renal Cell Carcinoma: Association With Adverse Clinicopathologic Factors and Poor Prognosis

OBJECTIVE

Aberrant expression of cadherins is known to be associated with tumor aggression. However, their role in clear cell renal cell carcinoma (CCRCC) is not well elucidated. This study investigated the expression of epithelial cadherin (E-cadherin), neural cadherin (N-cadherin), and placental cadherin (P-cadherin) in CCRCC, and assessed their prognostic significance and clinicopathologic association.

MATERIALS AND METHODS

We enrolled 254 patients with CCRCC who underwent radical or partial nephrectomy. E-cadherin, N-cadherin, and P-cadherin expression was evaluated by immunohistochemistry in a tissue microarray.

RESULTS

Low E-cadherin expression was associated with larger tumor size, lymphovascular invasion, higher pT stage, lymph node and distant metastasis, and higher stage. High N-cadherin expression was significantly associated with larger tumor size, higher nuclear grade, and tumor necrosis. P-cadherin expression was found to be significantly associated with higher nuclear grade, distant metastasis, and higher stage. Univariate analysis revealed that aberrant expression of the 3 cadherins was significantly related to shorter overall survival (OS). Loss of E-cadherin, high P-cadherin expression, and higher stage were independent prognostic factors for OS. For recurrence-free survival, lymphovascular invasion, high P-cadherin expression, and higher stage were independent prognostic factors. Cadherin switch was significantly associated with aggressive clinicopathologic factors and poor outcomes.

CONCLUSIONS

Aberrant expression of E-cadherin, N-cadherin, and P-cadherin was associated with adverse clinicopathologic factors and worse OS. Low E-cadherin and high P-cadherin expression were significantly associated with distant metastasis and independent prognostic factors. Therefore, cadherin expression may be used as a prognostic marker and therapeutic target, and cadherin switch plays an important role in CCRCC progression.

Increased expression of P-cadherin is an indicator of poor prognosis in breast cancer: a systematic review and meta-analysis

PURPOSE

P-cadherin (CDH3), located at 16q22.1 belonging to classical cadherin family, is a calcium-dependent glycoprotein associated with cell to cell adhesion, migration, and invasion in cancer. This meta-analysis was conducted to examine the prognostic utility of P-cadherin expression in breast cancer (BC).

METHODS

A comprehensive literature search was carried out using the available databases to obtain relevant research articles to test the relationship between P-cadherin and BC. Correlation of P-cadherin expression and disease-free survival (DFS) or overall survival (OS) was tested using hazard ratio (HR), relative risk (RR) at 95% confidence interval (CI) by univariate and/or multivariate analysis. A total of 11 studies from 7 countries were found to be relevant and were further subjected to statistical analysis to find an association between the P-cadherin expression with BC. Additionally, we have also performed a co-relation analysis of P-cadherin expression with GOBO and Cancertool in breast cancer using publicly available breast cancer datasets.

RESULTS

Our study shows that P-cadherin expression is significantly linked with poor prognosis in the various subtypes of BC. The HR for OS and DFS was 1.87 (95% CI = 1.48-2.36) and 1.64 (95% CI = 1.18-2.27) respectively.

CONCLUSIONS

In this meta-analysis, we identified a positive correlation between the overexpression of P-cadherin and BC. Our study demonstrates that P-cadherin overexpression can be used as a prognostic indicator in BC.

Design, synthesis, and validation of novel nitrogen-based chalcone analogs against triple negative breast cancer

Great strides have been made in triple negative breast cancer (TNBC) treatment, which represents 20% of total predicted annual US breast cancer (BC) cases. Despite the development of several therapeutics, TNBC patients have poor overall survival rate, compared to other BC patients, justifying the urgent need to discover new entities for use to control TNBC. Chalcones are important natural products with diverse bioactivities including anticancer effects. This study aimed to design, synthesize and validate novel chalcone leads as potential therapies for TNBC. Fourteen novel chalcone analogs were designed and synthesized comprising alicyclic amines (pyrrolidine, morpholine and piperidine) or nitrogen mustard (Bis-(2-chloroethyl) amine) substituents. Among them, compound 14((E)-3-(4-(Bis(2-chloroethyl) amino) phenyl)-1-(3-methoxyphenyl) prop-2-en-1-one) was identified as the most effective against TNBC and other BC phenotypes, with anti-proliferative IC₅₀ values ranging between 3.94 and 9.22 μM against the TNBC cell lines MDA-MB-231 and MDA-MB-468, as well as against the estrogen positive MCF-7 cell line. Chalcone 14 effectively suppressed the colony formation capacity of MDA-MB-231, MDA-MB-468, and MCF-7 cell lines at 5 and 10 μM treatment concentrations. Furthermore, compound 14 has significantly inhibited cell invasion and migration of MDA-MB-231 and MCF-7 BC cell lines. Additionally, compound 14 had significantly promoted apoptosis by upregulating BAX and downregulating Bcl-2 proteins. Compound 14 induced significant cell cycle arrest of TNBC cells at the G2/M phase. It also induced a reversal of Epithelial Mesenchymal Transition (EMT) by upregulating the epithelial markers E-cadherin and Pan-cadherin and downregulating FAK. Furthermore, it had dramatically diminished new vessel formation (vasculogenesis) in chick chorioallantoic membrane (CAM) model by 60.20 ± 8.47%. Chalcone 14 inhibited 46.41 ± 0.71% of the TNBC MAD-MB-231 cells growth in a nude mouse orthotopic xenograft model in comparison with vehicle control treated animals. Collectively, this study results propose chalcone 14 as a promising lead molecule for the control of TNBC as well as other breast cancer phenotypes.

KLF4-Mediated CDH3 Upregulation Suppresses Human Hepatoma Cell Growth and Migration via GSK-3β Signaling

P-cadherin (CDH3), a classical cell adhesion molecule involved in tissue integrity and cell localization, has been implicated in many types of cancer. However, little is known about its function and regulatory mechanism in hepatocellular carcinoma (HCC). Here we report that CDH3 was positively regulated by kr¨uppel-like transcription factor 4 (KLF4), which is a crucial tumor suppressor gene in HCC, at mRNA level in HCC cell lines. Luciferase reporter assay and chromatin immunoprecipitation assay indicated that KLF4 directly bound to CDH3 promoter and transcriptionally activated CDH3 expression. Consistently, CDH3 expression was closely related with KLF4 expression in patients' samples and both proteins exhibited a downregulated expression pattern in cancer samples. Functionally, enforced CDH3 expression suppressed and silenced CDH3 expression promoted HCC cell growth and migration in vitro. Mechanistically, we observed that GSK-3β was regulated by CDH3 and may function as a possible downstream effector of CDH3. Knockdown of GSK-3β showed a similar phenotype with CDH3 silencing. Taken together, these findings establish the KLF4/CDH3/GSK-3β axis as an important regulatory mechanism in HCC development.

[Identification of diagnostic tumour markers and therapeutic targets in testicular tumours]

Today, tumour classification has been expanded due to immunohistochemical and molecular-pathological analyses due to corresponding patterns/profiles of protein and gene expression. The latter analyses often include growth factors and their ligands, intracellular signalling pathways, DNA-binding proteins, and oncogenes and suppressor genes, thus functionally including primarily the regulation of growth including angiogenesis and apoptosis as well as the induction of metastases to adhesion and migration disorders. Based on observations that testicular tumours often show microcalcifications, possibly due to impaired calcium metabolism, we focused on calcium-dependent transmembrane proteins, particularly cadherins, in the search for new tumour markers and therapeutic targets. N‑cadherin is expressed differently in the various subtypes of germ cell tumours and is useful in N‑cadherin-positive germ cell tumours as a novel therapeutic targeting structure, particularly in cisplatin resistance, due to functional analysis. In the tumours of the sex cord stroma beta-catenin and the transcription factor SOX-9 give a clear classification of these tumours. Thus, morphological investigations prove to be pilot experiments to purposefully narrow the spectrum of functionally important proteins and thus to establish promising new differential diagnostic markers or target structures.

Disassembling a cancer puzzle: Cell junctions and plasma membrane as targets for anticancer therapy

Despite an enhanced permeability and retention effect typical of many solid tumors, drug penetration is not always sufficient. Possible strategies for the drug delivery improvement are a modification of the tumor cell-to-cell junctions and usage of cell membrane permeabilization proteins. In this review we discuss epithelial cell junctions as targets for a combined anticancer therapy and propose new possible sources of such agents. We suggest considering viral and bacterial pathogens disrupting epithelial layers as plentiful sources of new therapeutic agents for increasing tumor permeability for other effector agents. We also observe the application of pore forming proteins and peptides of different origin for cytoplasmic delivery of anti-cancer agents and consider the main obstacles of their use in vivo.

Exclusion from spheroid formation identifies loss of essential cell-cell adhesion molecules in colon cancer cells

Many cell lines derived from solid cancers can form spheroids, which recapitulate tumor cell clusters and are more representative of the in vivo situation than 2D cultures. During spheroid formation, a small proportion of a variety of different colon cancer cell lines did not integrate into the sphere and lost cell-cell adhesion properties. An enrichment protocol was developed to augment the proportion of these cells to 100% purity. The basis for the separation of spheroids from non-spheroid forming (NSF) cells is simple gravity-sedimentation. This protocol gives rise to sub-populations of colon cancer cells with stable loss of cell-cell adhesion. SW620 cells lacked E-cadherin, DLD-1 cells lost α-catenin and HCT116 cells lacked P-cadherin in the NSF state. Knockdown of these molecules in the corresponding spheroid-forming cells demonstrated that loss of the respective proteins were indeed responsible for the NSF phenotypes. Loss of the spheroid forming phenotype was associated with increased migration and invasion properties in all cell lines tested. Hence, we identified critical molecules involved in spheroid formation in different cancer cell lines. We present here a simple, powerful and broadly applicable method to generate new sublines of tumor cell lines to study loss of cell-cell adhesion in cancer progression.

Cadherin-1 and cadherin-3 cooperation determines the aggressiveness of pancreatic ductal adenocarcinoma

Background:

Pancreatic ductal adenocarcinoma (PDAC) is characterised by an extensive tissue invasion and an early formation of metastasis. Alterations in the expression of cadherins have been reported in PDAC. Yet, how these changes contribute to tumour progression is poorly understood. Here, we investigated the relationship between cadherins expression and PDAC development.

Methods:

Cadherins expression was assessed by immunostaining in both human and murine tissue specimens. We have generated pancreatic cancer cell lines expressing both cadherin-1 and cadherin-3 or only one of these cadherins. Functional implications of such genetic alterations were analysed both in vitro and in vivo.

Results:

Cadherin-3 is detected early at the plasma membrane during progression of pancreatic intraepithelial neoplasia 1 (PanIN-1) to PDAC. Despite tumoural cells turn on cadherin-3, a significant amount of cadherin-1 remains expressed at the cell surface during tumourigenesis. We found that cadherin-3 regulates tumour growth, while cadherin-1 drives type I collagen organisation in the tumour. In vitro assays showed that cadherins differentially participate to PDAC aggressiveness. Cadherin-3 regulates cell migration, whereas cadherin-1 takes part in the invadopodia activity.

Conclusions:

Our results show differential, but complementary, roles for cadherins during PDAC carcinogenesis and illustrate how their expression conditions the PDAC aggressiveness.

P-Cadherin (CDH3) is overexpressed in colorectal tumors and has potential as a serum marker for colorectal cancer monitoring

Introduction

Placental-Cadherin (CDH3) is a cell adhesion molecule vital to cellular localization and tissue integrity. It is highly expressed in the placenta (PLC)and is overexpressed by many types of cancer. P-cadherin levels in colorectal cancer (CRC) remains poorly characterized. This study's purpose was to determine P-cadherin expression in CRC and normal tissues and to assess plasma CDH3 levels in order to determine the relationship, if any, between cancer stage, P-cadherin expression and plasma CDH3 levels.

Methods

An IRB approved plasma, tumor, and prospective data bank was utilized. CRC patients for whom tumor and normal colon tissue samples were available were enrolled. Tumor samples were OCT embedded and stored at -80C°. Total purified RNA was isolated from tissue samples and cDNA synthesized. CDH3 expression was analyzed by quantitative PCR (QPCR) using the SYBR Green platform. Tumor expression levels were determined and compared to levels in normal colonic tissue and PLC. Expression in 22 different normal tissues was also assessed by RT-PCR. Plasma CDH3 levels were determined via ELISA in patients for whom preoperative blood samples were available. Results: A total of 77 paired CRC and normal colon specimens (36 M/ 41 F, age 67.3±14.5) were assessed (82% colon, 18% rectal; Cancer Stage 2, 44; Stage 3, 33). All tested tumors had CDH3 expression levels over 0.1% of the PLC level and tumor to normal colon ratios greater than 1. CDH3 expression was noted in 14/22 normal organ tissues. There was a positive correlation between tumor CDH3 QPCR and preoperative CDH3 blood levels (n=57, P= 0.038). Expression levels were significantly higher in rectal vs. colon tumors (p=0.019). Conclusion: CDH3 expression was elevated in CRC tumors as compared to normal tissue. CDH3 was expressed by numerous normal organs and, thus, is not a viable vaccine target, however, the correlation between plasma and tumor CDH3 levels suggests CDH3 may have value as a diagnostic or prognostic marker.

Quantitative comparison of the spreading and invasion of radial growth phase and metastatic melanoma cells in a three-dimensional human skin equivalent model

BACKGROUND

Standard two-dimensional (2D) cell migration assays do not provide information about vertical invasion processes, which are critical for melanoma progression. We provide information about three-dimensional (3D) melanoma cell migration, proliferation and invasion in a 3D melanoma skin equivalent (MSE) model. In particular, we pay careful attention to compare the structure of the tissues in the MSE with similarly-prepared 3D human skin equivalent (HSE) models. The HSE model is identically prepared to the MSE model except that melanoma cells are omitted. Using the MSE model, we examine melanoma migration, proliferation and invasion from two different human melanoma cell lines. One cell line, WM35, is associated with the early phase of the disease where spreading is thought to be confined to the epidermis. The other cell line, SK-MEL-28, is associated with the later phase of the disease where spreading into the dermis is expected.

METHODS

3D MSE and HSE models are constructed using human de-epidermised dermis (DED) prepared from skin tissue. Primary fibroblasts and primary keratinocytes are used in the MSE and HSE models to ensure the formation of a stratified epidermis, with a well-defined basement membrane. Radial spreading of cells across the surface of the HSE and MSE models is observed. Vertical invasion of melanoma cells downward through the skin is observed and measured using immunohistochemistry. All measurements of invasion are made at day 0, 9, 15 and 20, providing detailed time course data.

RESULTS

Both HSE and MSE models are similar to native skin in vivo, with a well-defined stratification of the epidermis that is separated from the dermis by a basement membrane. In the HSE and MSE we find fibroblast cells confined to the dermis, and differentiated keratinocytes in the epidermis. In the MSE, melanoma cells form colonies in the epidermis during the early part of the experiment. In the later stage of the experiment, the melanoma cells in the MSE invade deeper into the tissues. Interestingly, both the WM35 and SK-MEL-28 melanoma cells lead to a breakdown of the basement membrane and eventually enter the dermis. However, these two cell lines invade at different rates, with the SK-MEL-28 melanoma cells invading faster than the WM35 cells.

DISCUSSION

The MSE and HSE models are a reliable platform for studying melanoma invasion in a 3D tissue that is similar to native human skin. Interestingly, we find that the WM35 cell line, that is thought to be associated with radial spreading only, is able to invade into the dermis. The vertical invasion of melanoma cells into the dermal region appears to be associated with a localised disruption of the basement membrane. Presenting our results in terms of time course data, along with images and quantitative measurements of the depth of invasion extends previous 3D work that has often been reported without these details.

Heterocellular cadherin connections: coordinating adhesive cues in homeostasis and cancer

This short insight covers some of the recent topics relevant to the field of cadherin-catenin adhesion in mediating connections between different cell types, so-called heterotypic or heterocellular connections, in both homeostasis and cancer. These scientific discoveries are increasing our understanding of how multiple cells residing in complex tissues can be instructed by cadherin adhesion receptors to regulate tissue architecture and function and how these cadherin-mediated heterocellular connections spur tumor growth and the acquisition of malignant characteristics in tumor cells. Overall, the findings that have emerged over the past few years are elucidating the complexity of the functional roles of the cadherin-catenin complexes. Future exciting research lies ahead in order to understand the physical basis of these heterotypic interactions and their influence on the behavior of heterogeneous cellular populations as well as their roles in mediating phenotypic and genetic changes as cells evolve through complex environments during morphogenesis and cancer.

Discovery of novel plasma proteins as biomarkers for the development of incisional hernias after midline incision in patients with colorectal cancer: The ColoCare study

BACKGROUND

Ventral incisional hernia is the most common long-term complication after an abdominal operation. Among newly diagnosed colorectal cancer patients, we screened the preoperative plasma proteome to explore predictive markers for the development of an incisional hernia.

METHODS

We utilized preoperative plasma samples of 72 newly diagnosed colorectal cancer patients who underwent midline incision for tumor resection between 2010 and 2013. A total of 21 patients with incisional hernia occurrence were matched with 51 patients with at least 18 months follow-up without an incisional hernia by sex, age, and body mass index. To assess predictive markers of incisional hernia risk, we screened the plasma proteome for >2,000 distinct proteins using a well-validated antibody microarray test. Paired t tests were used to compare protein levels between cases and controls. A gene-set-enrichment analysis (Gene Ontology and Kyoto Encyclopedia of Genes and Genomes) was applied to test for differences in signaling pathways between the 2 groups.

RESULTS

The proteome screen identified 25 proteins that showed elevated or reduced plasma levels in the hernia group compared to the control group (nominal P values < .05). Several proteins were in pathways associated with wound healing (CCL21, SHBG, BRF2) or cell adhesion (PCDH15, CDH3, EPCAM).

CONCLUSION

Our study shows that there are multiple individual and groups of plasma proteins that could feasibly predict the personal hernia risk prior to undergoing an operation. Further investigations in larger, independent sample sets are warranted to replicate findings and validate clinical utility of potential biomarkers. After validation, such a biomarker could be incorporated into a multifactorial risk model to guide clinical decision-making.

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.

Significance of P-cadherin overexpression and possible mechanism of its regulation in intrahepatic cholangiocarcinoma and pancreatic cancer

It has become evident that P-cadherin, one of the classical cadherins, contributes to the malignant behavior of several types of cancer. In this study, we analyzed the expression of P-cadherin and its clinicopathological and prognostic values in intrahepatic cholangiocarcinoma (ICC) and pancreatic cancer. Furthermore, we investigated the functional role of P-cadherin in these cancer cells by knockdown and overexpression in vitro and by analyzing the correlation between the P-cadherin expression and its promoter methylation status. Thirty of 59 ICC cases (51%) and 36 of 73 pancreatic cancer cases (49%) stained positive for P-cadherin with mainly membranous distribution in tumor cells by immunohistochemistry. P-cadherin expression was significantly correlated with several clinicopathological factors, which reflect tumor behavior, and was identified as an independent adverse prognostic factor for disease-free survival in patients with ICC (relative risk [RR] 2.93, P = 0.04) and pancreatic cancer (RR 2.68, P = 0.005) via multivariate analyses. P-cadherin downregulation by siRNA suppressed migration and invasion, and P-cadherin overexpression induced the opposite effects in both ICC and pancreatic cancer cells, without any effects on cell proliferation. P-cadherin expression was related to its promoter methylation status in both cell lines and cancer tissues. In summary, P-cadherin overexpression may serve as a useful biomarker of invasive phenotype and poor prognosis; P-cadherin expression was found to be regulated by its promoter methylation. These results suggest that P-cadherin represents a novel therapeutic target for the treatment of ICC and pancreatic cancer.

Expression array analysis of the hepatocyte growth factor invasive program

Signaling by human hepatocyte growth factor (hHGF) via its cell surface receptor (MET) drives mitogenesis, motogenesis and morphogenesis in a wide spectrum of target cell types and embryologic, developmental and homeostatic contexts. Oncogenic pathway activation also contributes to tumorigenesis and cancer progression, including tumor angiogenesis and metastasis, in several prevalent malignancies. The HGF gene encodes full-length hHGF and two truncated isoforms known as NK1 and NK2. NK1 induces all three HGF activities at modestly reduced potency, whereas NK2 stimulates only motogenesis and enhances HGF-driven tumor metastasis in transgenic mice. Prior studies have shown that mouse HGF (mHGF) also binds with high affinity to human MET. Here we show that, like NK2, mHGF stimulates cell motility, invasion and spontaneous metastasis of PC3M human prostate adenocarcinoma cells in mice through human MET. To identify target genes and signaling pathways associated with motogenic and metastatic HGF signaling, i.e., the HGF invasive program, gene expression profiling was performed using PC3M cells treated with hHGF, NK2 or mHGF. Results obtained using Ingenuity Pathway Analysis software showed significant overlap with networks and pathways involved in cell movement and metastasis. Interrogating The Cancer Genome Atlas project also identified a subset of 23 gene expression changes in PC3M with a strong tendency for co-occurrence in prostate cancer patients that were associated with significantly decreased disease-free survival.

Chick Heart Invasion Assay for Testing the Invasiveness of Cancer Cells and the Activity of Potentially Anti-invasive Compounds

The goal of the chick heart assay is to offer a relevant organ culture method to study tumor invasion in three dimensions. The assay can distinguish between invasive and non-invasive cells, and enables study of the effects of test compounds on tumor invasion. Cancer cells - either as aggregates or single cells - are confronted with fragments of embryonic chick heart. After organ culture in suspension for a few days or weeks the confronting cultures are fixed and embedded in paraffin for histological analysis. The three-dimensional interaction between the cancer cells and the normal tissue is then reconstructed from serial sections stained with hematoxylin-eosin or after immunohistochemical staining for epitopes in the heart tissue or the confronting cancer cells. The assay is consistent with the recent concept that cancer invasion is the result of molecular interactions between the cancer cells and their neighbouring stromal host elements (myofibroblasts, endothelial cells, extracellular matrix components, etc.). Here, this stromal environment is offered to the cancer cells as a living tissue fragment. Supporting aspects to the relevance of the assay are multiple. Invasion in the assay is in accordance with the criteria of cancer invasion: progressive occupation and replacement in time and space of the host tissue, and invasiveness and non-invasiveness in vivo of the confronting cells generally correlates with the outcome of the assay. Furthermore, the invasion pattern of cells in vivo, as defined by pathologists, is reflected in the histological images in the assay. Quantitative structure-activity relation (QSAR) analysis of the results obtained with numerous potentially anti-invasive organic congener compounds allowed the study of structure-activity relations for flavonoids and chalcones, and known anti-metastatic drugs used in the clinic (e.g., microtubule inhibitors) inhibit invasion in the assay as well. However, the assay does not take into account immunological contributions to cancer invasion.

The X-ray structure of human P-cadherin EC1-EC2 in a closed conformation provides insight into the type I cadherin dimerization pathway

Cadherins are a large family of calcium-dependent proteins that mediate cellular adherens junction formation and tissue morphogenesis. To date, the most studied cadherins are those classified as classical, which are further divided into type I or type II depending on selected sequence features. Unlike other members of the classical cadherin family, a detailed structural characterization of P-cadherin has not yet been fully obtained. Here, the high-resolution crystal structure determination of the closed form of human P-cadherin EC1-EC2 is reported. The structure shows a novel, monomeric packing arrangement that provides a further snapshot in the yet-to-be-achieved complete description of the highly dynamic cadherin dimerization pathway. Moreover, this is the first multidomain cadherin fragment to be crystallized and structurally characterized in its closed conformation that does not carry any extra N-terminal residues before the naturally occurring aspartic acid at position 1. Finally, two clear alternate conformations are observed for the critical Trp2 residue, suggestive of a transient, metastable state. The P-cadherin structure and packing arrangement shown here provide new and valuable information towards the complete structural characterization of the still largely elusive cadherin dimerization pathway.

Control of cell-cell forces and collective cell dynamics by the intercellular adhesome

Dynamics of epithelial tissues determine key processes in development, tissue healing and cancer invasion. These processes are critically influenced by cell-cell adhesion forces. However, the identity of the proteins that resist and transmit forces at cell-cell junctions remains unclear, and how these proteins control tissue dynamics is largely unknown. Here we provide a systematic study of the interplay between cell-cell adhesion proteins, intercellular forces and epithelial tissue dynamics. We show that collective cellular responses to selective perturbations of the intercellular adhesome conform to three mechanical phenotypes. These phenotypes are controlled by different molecular modules and characterized by distinct relationships between cellular kinematics and intercellular forces. We show that these forces and their rates can be predicted by the concentrations of cadherins and catenins. Unexpectedly, we identified different mechanical roles for P-cadherin and E-cadherin; whereas P-cadherin predicts levels of intercellular force, E-cadherin predicts the rate at which intercellular force builds up.

P-Cadherin Linking Breast Cancer Stem Cells and Invasion: A Promising Marker to Identify an "Intermediate/Metastable" EMT State

Epithelial–mesenchymal transition (also known as EMT) is a fundamental mechanism occurring during embryonic development and tissue differentiation, being also crucial for cancer progression. Actually, the EMT program contributes to the dissemination of cancer cells from solid tumors and to the formation of micro-metastasis that subsequently develop into clinically detectable metastases. Besides being a process that is defined by the progressive loss of epithelial cell characteristics and the acquisition of mesenchymal features, EMT has also been implicated in therapy resistance, immune escape, and maintenance of cancer stem cell properties, such as self-renewal capacity. However, the majority of the studies usually neglect the progressive alterations occurring during intermediate EMT states, which imply a range of phenotypic cellular heterogeneity that can potentially generate more metastable and plastic tumor cells. In fact, few studies have tried to identify these transitory states, partly due to the current lack of a detailed understanding of EMT, as well as of reliable readouts for its progression. Herein, a brief review of evidences is presented, showing that P-cadherin expression, which has been already identified as a breast cancer stem cell marker and invasive promoter, is probably able to identify an intermediate EMT state associated with a metastable phenotype. This hypothesis is based on our own work, as well as on the results described by others, which suggest the use of P-cadherin as a promising EMT marker, clearly functioning as an important clinical prognostic factor and putative therapeutic target in breast carcinogenesis.

P-cadherin potentiates ligand-dependent EGFR and IGF-1R signaling in dysplastic and malignant oral keratinocytes

Oral and oropharyngeal cancer together constitute the sixth most common cancer worldwide, with over 400,000 new cases diagnosed each year. Early detection is paramount, as the 5-year survival rate for these cancers decreases markedly once tumors have become regionally invasive. In many tissues, including oral epithelia, neoplastic progression is accompanied by alterations in expression of the epithelial cell adhesion molecules E-cadherin and P-cadherin. Oral epithelia is one of only a few tissues in which P-cadherin levels have been noted to increase in dysplasia and well-differentiated carcinomas and decrease in advanced malignancies. In the present study, P-cadherin was overexpressed in both dysplastic and malignant oral keratinocytes to characterize the mechanisms by which aberrantly expressed P-cadherin may modulate tumor progression. We found that P-cadherin was able to potentiate ligand-dependent signaling of insulin-like growth factor 1 receptor (IGF-1R) in malignant keratinocytes and epidermal growth factor receptor (EGFR) in dysplastic cells. P-cadherin prolonged activation of the mitogen-activated protein kinase (MAPK) in both cell lines and also increased the magnitude of AKT phosphorylation in dysplastic cells. P-cadherin overexpression alone was sufficient to increase steady-state levels of the mesenchymal transcription factor Snail, increase cell motility and also induce morphological changes in dysplastic keratinocytes. Taken together, these data suggest that the aberrantly elevated levels of P-cadherin which occur in early oral tumor development may play a critical role in the augmentation of neoplastic signaling networks and in the further acquisition of aggressive phenotypes.

HOXA9 promotes homotypic and heterotypic cell interactions that facilitate ovarian cancer dissemination via its induction of P-cadherin

Background

Epithelial ovarian cancer (EOC) is a lethal disease that frequently involves the peritoneal cavity. Dissemination of EOC is a multi-step process in which exfoliated tumor cells survive in the peritoneal fluid as multi-cellular aggregates and then form invasive implants on peritoneal surfaces. The mechanisms that control this process are poorly understood. We previously identified that high expression of the developmental patterning gene HOXA9 is associated with poor survival in EOC patients. In this study, we investigated the significance and mechanisms of HOXA9 in controlling aggregation and implantation of floating EOC cells.

Methods

HOXA9 was inhibited by shRNAs or expressed in EOC cells that were propagated in suspension cultures and in the peritoneal cavity of mice. Cell death was assayed by flow cytometry and ELISA. Cell aggregation, attachment and migration were evaluated by microscopy, transwell chamber assays and histopathologic analysis. DNA-binding of HOXA9 and its effect on expression of the cell adhesion molecule P-cadherin were assayed by chromatin immunoprecipitation, quantitative RT-PCR and Western blot. HOXA9 and P-cadherin expression was evaluated in publicly available datasets of EOC clinical specimens.

Results

We identified that HOXA9 promotes aggregation and inhibits anoikis in floating EOC cells in vitro and in xenograft models. HOXA9 also stimulated the ability of EOC cells to attach to peritoneal cells and to migrate. HOXA9 bound the promoter of the CDH3 gene that encodes P-cadherin, induced CDH3 expression in EOC cells, and was associated with increased CDH3 expression in clinical specimens of EOC. Inhibiting P-cadherin in EOC cells that expressed HOXA9 abrogated the stimulatory effects of HOXA9 on cell aggregation, implantation and migration. Conversely, these stimulatory effects of HOXA9 were restored when P-cadherin was reconstituted in EOC cells in which HOXA9 was inhibited.

Conclusion

These findings indicate that HOXA9 contributes to poor outcomes in EOC in part by promoting intraperitoneal dissemination via its induction of P-cadherin.

Chick heart invasion assay

Tumors are microecosystems in which a continuous cross talk between cancer cells and host cells decides on the invasive behavior of the tumor cell population as a whole (Mareel et al., Encyclopedia of cancer, San Diego, CA, Academic Press, 1997). Both compartments secrete activating and inhibitory factors that modulate activities such as cell-extracellular matrix (ECM) interaction, cell-cell adhesion, remodeling of the ECM, and cell motility. For this reason, confrontations of cancer cells with a living normal host tissue in organ culture have been introduced by several groups: Wolff and Schneider in France (Wolff and Schneider, C R S Soc Biol (Paris) 151:1291-1292, 1957), Easty and Easty in the United Kingdom (Easty and Easty, Nature 199:1104-1105, 1963), and Schleich in Germany (Schleich et al., J Natl Cancer Inst 56:221-237, 1976). Embryonic chick heart fragments in organ culture maintain many histological features of their tissue of origin: They are composed of myocytes, fibroblasts, and endothelial cells, and their ECM contains fibronectin, laminin, and several collagen types. Moreover, the fragments remain contractile, and this activity allows the monitoring of their functional integrity during organ culture.

Identification and characterization of the X-dimer of human P-cadherin: implications for homophilic cell adhesion

Cell adhesion mediated by cadherins depends critically on the homophilic trans-dimerization of cadherin monomers from apposing cells, generating the so-called strand-swap dimer (ss-dimer). Recent evidence indicates that the ss-dimer is preceded by an intermediate species known as the X-dimer. Until now, the stabilized form of the X-dimer had only been observed in E-cadherin among the classical type I cadherins. Herein, we report the isolation and characterization of the analogous X-dimer of human P-cadherin. Small-angle X-ray scattering (SAXS) and site-directed mutagenesis data indicates that the overall architecture of the X-dimer of human P-cadherin is similar to that of E-cadherin. The X-dimerization is triggered by Ca(2+) and governed by specific protein-protein interactions. The attachment of three molecules of Ca(2+) with high affinity (Kd = 9 μM) stabilizes the monomeric conformation of P-cadherin (ΔTm = 17 °C). The Ca(2+)-stabilized monomer subsequently dimerizes in the X-configuration by establishing protein-protein interactions that require the first two extracellular domains of the cadherin. The homophilic X-dimerization is very specific, as the presence of the highly homologous E-cadherin does not interfere with the self-recognition of P-cadherin. These data suggest that the X-dimer could play a key role in the specific cell-cell adhesion mediated by human P-cadherin.

N-cadherin and P-cadherin are biomarkers for invasion, metastasis, and poor prognosis of gallbladder carcinomas

Gallbladder cancer (GBC) is a rare, but highly aggressive cancer. The most common type of gallbladder cancer is adenocarcinoma (AC), while squamous cell/adenosquamous carcinoma (SC/ASC) is a rare type of gallbladder cancer. The clinicopathologic and biological characteristics of SC/ASC have not been well documented. In this study, the protein expression of N-cadherin and P-cadherin in 46 SC/ASCs and 80 ACs was measured using immunohistochemistry. We demonstrated that positive N-cadherin and P-cadherin expression were significantly associated with large tumor size, invasion, and lymph node metastasis of both SC/ASC and AC. In contrast, positive N-cadherin and P-cadherin expression were significantly associated with differentiation and TNM stage in only AC. Univariate Kaplan-Meier analysis showed that positive N-cadherin and P-cadherin expression, differentiation, tumor size, TNM stage, invasion, lymph node metastasis, and surgical curability were significantly associated with overall survival in both SC/ASC and AC patients. Multivariate Cox regression analysis showed that positive N-cadherin and P-cadherin expression are independent poor-prognostic factors in both SC/ASC and AC patients. Our study suggested that positive N-cadherin and P-cadherin expression closely correlated with clinicopathological and biological behaviors, and poor-prognosis of gallbladder cancer.

Desmoglein 2 depletion leads to increased migration and upregulation of the chemoattractant secretoneurin in melanoma cells

During development and progression of malignant melanoma, an important role has been attributed to alterations of cell-cell adhesions, in particular, to a “cadherin switch” from E- to N-cadherin. We have previously shown that a subtype of melanoma cells express the desmosomal cadherin desmoglein 2 as non-junction-bound cell surface protein in addition to classical cadherins. To study the role of desmoglein 2 in melanoma cells, melanoma lines containing high endogenous amounts of desmoglein 2 were depleted of the protein by RNA interference. Transwell migration and scratch wounding assays showed markedly increased migration upon desmoglein 2 suppression whereas proliferation and viability remained unaltered. In gene expression profiles, desmoglein 2 depletion was associated with overexpression of migration-related genes. Strongest overexpression was found for secretogranin II which has not been reported in melanoma cells before. The bioactive peptide derived from secretogranin II, secretoneurin, is known to exert chemoattractive functions and was demonstrated here to stimulate melanoma cell migration. In summary, we show that desmoglein 2 expression attenuates migration of melanoma cells. The mechanism of desmoglein 2 impaired cell migration is mediated by downregulation of secretogranin II. Loss of desmoglein 2 increases expression of secretogranin II, followed by an enhanced migratory activity of melanoma cells. Our data add a new pathway of regulating melanoma cell migration related to a desmoglein 2 – secretogranin II axis.

Beyond E-cadherin: roles of other cadherin superfamily members in cancer

Loss of cadherin 1 (CDH1; also known as epithelial cadherin (E-cadherin)) is used for the diagnosis and prognosis of epithelial cancers. However, it should not be ignored that the superfamily of transmembrane cadherin proteins encompasses more than 100 members in humans, including other classical cadherins, numerous protocadherins and cadherin-related proteins. Elucidation of their roles in suppression versus initiation or progression of various tumour types is a young but fascinating field of molecular cancer research. These cadherins are very diverse in both structure and function, and their mutual interactions seem to influence biological responses in complex and versatile ways.

P-cadherin promotes ovarian cancer dissemination through tumor cell aggregation and tumor-peritoneum interactions

More than 60% of patients who are diagnosed with epithelial ovarian cancer (EOC) present with extensive peritoneal carcinomatosis. EOC cells typically disseminate by shedding into the peritoneal fluid in which they survive as multicellular aggregates and then implant onto peritoneal surfaces. However, the mechanism that facilitates aggregation and implantation of EOC cells is poorly understood. The cell adhesion molecule P-cadherin has been reported to be induced during early progression of EOC and to promote tumor cell migration. In this study, P-cadherin not only promoted migration of EOC cells, but also facilitated the assembly of floating EOC cells into multicellular aggregates and inhibited anoikis in vitro. Furthermore, inhibiting P-cadherin by short hairpin RNAs (shRNA) or a neutralizing antibody prevented EOC cells from attaching to peritoneal mesothelial cells in vitro. In mouse intraperitoneal xenograft models of EOC, inhibition of P-cadherin decreased the aggregation and survival of floating tumor cells in ascites and reduced the number of tumor implants on peritoneal surfaces. These findings indicate that P-cadherin promotes intraperitoneal dissemination of EOC by facilitating tumor cell aggregation and tumor-peritoneum interactions in addition to promoting tumor cell migration.

IMPLICATIONS

Inhibiting P-cadherin blocks multiple key steps of EOC progression and has therapeutic potential.

Cell aggregation assays

Invasion of carcinoma cells is the result of a disequilibrium between invasion promoter and invasion suppressor gene products (Mareel and Van Roy, Anticancer Res 6:419-435, 1986). The E-cadherin/catenin complex is the most potent invasion suppressor at the cell membrane of epithelioid cells (Duffy et al., J Pathol 214:283-293, 2008). This complex consists of E-cadherin, a transmembrane glycoprotein of 120 kDa, which is linked to the actin cytoskeleton via the catenins (Behrens et al., J Cell Biol 108:2435-2447, 1989). Downregulation of the complex is a common feature in invasive carcinoma cells, and has been recognized at several levels, ranging from genomic mutations to functional deficiencies of an apparently intact complex (Ozawa et al., Proc Natl Acad Sci USA 87:4246-4250, 1990). Cell aggregation assays have been set up to test the functionality of the complex in epithelioid tumor cells. Functional integrity of the complex is a prerequisite for cell-cell adhesion between epithelial cells, and measuring cell aggregation in vitro has thus become another elegant tool to study differences between invasive and noninvasive cell types.

Targeted liposome-loaded microbubbles for cell-specific ultrasound-triggered drug delivery

One of the main problems in cancer treatment is disease relapse through metastatic colonization, which is caused by circulating tumor cells (CTCs). This work reports on liposome-loaded microbubbles targeted to N-cadherin, a cell-cell adhesion molecule expressed by CTCs. It is shown that such microbubbles can indeed bind to N-cadherin at the surface of HMB2 cells. Interestingly, in a mixture of cells with and without N-cadherin expression, binding of the liposome-loaded microbubbles mainly occurs to the N-cadherin-expressing cells. Importantly, applying ultrasound results in the intracellular delivery of a model drug (loaded in the liposomes) in the N-cadherin-expressing cells only. As described in this paper, such liposome-loaded microbubbles may find application as theranostics and in devices aimed for the specific killing of CTCs in blood.

The bacterial protein azurin impairs invasion and FAK/Src signaling in P-cadherin-overexpressing breast cancer cell models

P-cadherin overexpression occurs in about 30% of all breast carcinomas, being a poor prognostic factor for breast cancer patients. In a cellular background of wild-type E-cadherin, we have previously shown that its expression promotes invasion, motility and migration of breast cancer cells due to the induced secretion of metalloproteases (MMPs) to the extracellular medium and to the concomitant shedding of a pro-invasive soluble form of this protein (sP-cad). Azurin is secreted by Pseudomonas aeruginosa and induces in vitro and in vivo cytotoxicity after its preferential penetration in human cancer cells relative to normal cells. Three different breast cancer cell lines, MCF-7/AZ.Mock, MCF-7/AZ.Pcad and SUM149 were treated with sub-killing doses of azurin. Invasion of these cells was measured using Matrigel Invasion Assays and MTT assays were performed to determine cell viability upon treatment and the effects on cadherins expression was determined by Western blot and Immunofluorescence. Gelatin Zymography was used to determine activity of MMP2 in the conditioned media of azurin treated and untreated cells and the phosphorylation levels of intracellular signaling proteins were determined by Western blot. The invasive phenotype of these breast cancer cells was significantly reduced by azurin. Azurin (50–100 µM) also caused a specific decrease on P-cadherin protein levels from 30–50% in MCF-7/AZ.Pcad and SUM149 breast cancer cell lines, but the levels of E-cadherin remain unaltered. More, the levels of sP-cad and the activity of MMP2 were reduced in the extracellular media of azurin treated cells and we also observed a decrease in the phosphorylation levels of both FAK and Src proteins. Our data show that azurin specifically targets P-cadherin, not E-cadherin, abrogating P-cadherin-mediated invasive effects and signaling. Therefore, azurin could possibly be considered a therapeutic tool to treat poor-prognosis breast carcinomas overexpressing P-cadherin in a wild type E-cadherin context.

Modeling the mechanics of cancer: effect of changes in cellular and extra-cellular mechanical properties

Malignant transformation, though primarily driven by genetic mutations in cells, is also accompanied by specific changes in cellular and extra-cellular mechanical properties such as stiffness and adhesivity. As the transformed cells grow into tumors, they interact with their surroundings via physical contacts and the application of forces. These forces can lead to changes in the mechanical regulation of cell fate based on the mechanical properties of the cells and their surrounding environment. A comprehensive understanding of cancer progression requires the study of how specific changes in mechanical properties influences collective cell behavior during tumor growth and metastasis. Here we review some key results from computational models describing the effect of changes in cellular and extra-cellular mechanical properties and identify mechanistic pathways for cancer progression that can be targeted for the prediction, treatment, and prevention of cancer.

Switch of cadherin expression as a diagnostic tool for Leydig cell tumours

Leydig cell tumours comprise about 3% of all testicular tumours. The pathogenesis of Leydig cell tumours is still poorly understood. We investigated testis with Leydig cell hyperplasia and Leydig cell tumours for their expression pattern of P- and N-cadherin. We could show a switch of expression of P- and N-cadherin in Leydig cell hyperplasia and Leydig cell tumours in comparison with normal Leydig cells. Cadherins could be established as a new immunohistochemical marker for this testicular tumour entity; their possible role in tumour genesis will be discussed.

CCAAT/enhancer binding protein β (C/EBPβ) isoforms as transcriptional regulators of the pro-invasive CDH3/P-cadherin gene in human breast cancer cells

P-cadherin is a cell-cell adhesion molecule codified by the CDH3 gene, which expression is highly associated with undifferentiated cells in normal adult epithelial tissues, as well as with poorly differentiated carcinomas. In breast cancer, P-cadherin is frequently overexpressed in high-grade tumours and is a well-established indicator of aggressive tumour behaviour and poor patient prognosis. However, till now, the mechanisms controlling CDH3 gene activation have been poorly explored. Since we recently described the existence of several CCAAT/Enhancer Binding Protein β (C/EBPβ) transcription factor binding sites at the CDH3 promoter, the aim of this study was to assess if the distinct C/EBPβ isoforms were directly involved in the transcriptional activation of the CDH3 gene in breast cancer cells. DNA-protein interactions, mutation analysis and luciferase reporter assay studies have been performed. We demonstrated that C/EBPβ is co-expressed with P-cadherin in breast cancer cells and all the three isoforms function as transcriptional regulators of the CDH3 gene, directly interacting with specific regions of its promoter. Interestingly, this transcriptional activation was only reflected at the P-cadherin protein level concerning the LIP isoform. Taken together, our data show that CDH3 is a newly defined transcriptional target gene of C/EBPβ isoforms in breast cancer, and we also identified the binding sites that are relevant for this activation.

P-cadherin functional role is dependent on E-cadherin cellular context: a proof of concept using the breast cancer model

P-cadherin overexpression is associated with worse breast cancer survival, being a poor prognostic marker as well as a putative therapeutic target for the aggressive triple-negative and basal-like carcinomas (TNBCs). Previously, we have shown that P-cadherin promotes breast cancer invasion of cells where membrane E-cadherin was maintained; however, it suppresses invasion in models without endogenous cadherins, like melanomas. Here, we investigated if P-cadherin expression would interfere with the normal adhesion complex and which were the cellular/molecular consequences, constituting, in this way, a new mechanism by which E-cadherin invasive-suppressor function was disrupted. Using breast TNBC models, we demonstrated, for the first time, that P-cadherin co-localizes with E-cadherin, promoting cell invasion due to the disruption caused in the interaction between E-cadherin and cytoplasmic catenins. P-cadherin also induces cell migration and survival, modifying the expression profile of cells expressing wild-type E-cadherin and contributing to alter their cellular behaviour. Additionally, E- and P-cadherin co-expressing cells significantly enhanced in vivo tumour growth, compared with cells expressing only E- or only P-cadherin. Finally, we still found that co-expression of both molecules was significantly correlated with high-grade breast carcinomas, biologically aggressive, and with poor patient survival, being a strong prognostic factor in this disease. Our results show a role for E- and P-cadherin co-expression in breast cancer progression and highlight the potential benefit of targeting P-cadherin in the aggressive tumours expressing high levels of this protein.

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.

Down-regulation of P-cadherin with PF-03732010 inhibits cell migration and tumor growth in gastric cancer

P-cadherin is frequently up-regulated in solid tumors such as gastric, colon, lung, pancreatic and breast cancers. Although P-cadherin promotes cadherin-mediated cell adhesion, the gastric cancer-linked regulation of P-cadherin has not been extensively investigated. In this study, we found epigenetic regulation of P-cadherin in human gastric cancer cells that was induced by treatment with DNA demethylating drug and histone deacetylase inhibitor. Silencing P-cadherin by using siRNA induces apoptosis in gastric cells and blocks expression of Tie-2, an angiogenic receptor tyrosine kinase. In contrast, ectopically expressed P-cadherin by generating P-cadherin stable cell line enhances Tie-2 expression and cell mobility. We also demonstrated that inhibition of P-cadherin by PF-03732010, a fully humanized anti-P-cadherin IgG1 monoclonal antibody, suppressed cell migration in vitro and tumor growth in BALB/c nude mice bearing SNU620 gastric cancer xenograft. The data reported here are the first to reveal that the inhibition of P-cadherin decreases tumor cell migration and blocks a tumorigenesis by down-regulation of Tie-2 in gastric cancer. This demonstrates the potential for P-cadherin to be used as a target for treatment of gastric cancer.

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

BACKGROUND

 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.

OBJECTIVES

To examine the prevalence and prognostic relevance of E-, N- and P-cadherin in MCCs.

METHODS

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.

RESULTS

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).

CONCLUSION

P-cadherin expression in MCCs predicts prolonged recurrence-free survival and may therefore indicate favourable prognosis.

ALCAM regulates motility, invasiveness, and adherens junction formation in uveal melanoma cells

ALCAM, a member of the immunoglobulin superfamily, has been implicated in numerous developmental events and has been repeatedly identified as a marker for cancer metastasis. Previous studies addressing ALCAM's role in cancer have, however, yielded conflicting results. Depending on the tumor cell type, ALCAM expression has been reported to be both positively and negatively correlated with cancer progression and metastasis in the literature. To better understand how ALCAM might regulate cancer cell behavior, we utilized a panel of defined uveal melanoma cell lines with high or low ALCAM levels, and directly tested the effects of manipulating these levels on cell motility, invasiveness, and adhesion using multiple assays. ALCAM expression was stably silenced by shRNA knockdown in a high-ALCAM cell line (MUM-2B); the resulting cells displayed reduced motility in gap-closure assays and a reduction in invasiveness as measured by a transwell migration assay. Immunostaining revealed that the silenced cells were defective in the formation of adherens junctions, at which ALCAM colocalizes with N-cadherin and ß-catenin in native cells. Additionally, we stably overexpressed ALCAM in a low-ALCAM cell line (MUM-2C); intriguingly, these cells did not exhibit any increase in motility or invasiveness, indicating that ALCAM is necessary but not sufficient to promote metastasis-associated cell behaviors. In these ALCAM-overexpressing cells, however, recruitment of ß-catenin and N-cadherin to adherens junctions was enhanced. These data confirm a previously suggested role for ALCAM in the regulation of adherens junctions, and also suggest a mechanism by which ALCAM might differentially enhance or decrease invasiveness, depending on the type of cadherin adhesion complexes present in tissues surrounding the primary tumor, and on the cadherin status of the tumor cells themselves.