Cell adhesion molecule L1 disrupts E-cadherin-containing adherens junctions and increases scattering and motility of MCF7 breast carcinoma cells

Induction of stearoyl-CoA desaturase confers cell density-dependent ferroptosis resistance in melanoma

Ferroptosis is a form of regulated cell death that is induced by inhibiting glutathione peroxidase 4 (GPX4), which eliminates lipid peroxidation. Ferroptosis induction is influenced by the cell environment. However, the cellular states altering ferroptosis susceptibility remain largely unknown. We found that melanoma cell lines became resistant to ferroptosis as cell density increased. Comparative transcriptome and metabolome analyses revealed that cell density-dependent ferroptosis resistance was coupled with a shift toward a lipogenic phenotype accompanied by strong induction of stearoyl-CoA desaturase (SCD). Database analysis of gene dependency across hundreds of cancer cell lines uncovered a negative correlation between GPX4 and SCD dependency. Importantly, SCD inhibition, either pharmacologically or through genetic knockout, sensitized melanoma cells to GPX4 inhibition, thereby attenuating ferroptosis resistance in cells at high density. Our findings indicate that transition to an SCD-inducing, lipogenic cell state produces density-dependent resistance to ferroptosis, which may provide a therapeutic strategy against melanoma.

Androgen drives melanoma invasiveness and metastatic spread by inducing tumorigenic fucosylation

Melanoma incidence and mortality rates are historically higher for men than women. Although emerging studies have highlighted tumorigenic roles for the male sex hormone androgen and its receptor (AR) in melanoma, cellular and molecular mechanisms underlying these sex-associated discrepancies are poorly defined. Here, we delineate a previously undisclosed mechanism by which androgen-activated AR transcriptionally upregulates fucosyltransferase 4 (FUT4) expression, which drives melanoma invasiveness by interfering with adherens junctions (AJs). Global phosphoproteomic and fucoproteomic profiling, coupled with in vitro and in vivo functional validation, further reveal that AR-induced FUT4 fucosylates L1 cell adhesion molecule (L1CAM), which is required for FUT4-increased metastatic capacity. Tumor microarray and gene expression analyses demonstrate that AR-FUT4-L1CAM-AJs signaling correlates with pathological staging in melanoma patients. By delineating key androgen-triggered signaling that enhances metastatic aggressiveness, our findings help explain sex-associated clinical outcome disparities and highlight AR/FUT4 and its effectors as potential prognostic biomarkers and therapeutic targets in melanoma.

N-BAR and F-BAR proteins-endophilin-A3 and PSTPIP1-control clathrin-independent endocytosis of L1CAM

Recent advances in the field demonstrate the high diversity and complexity of endocytic pathways. In the current study, we focus on the endocytosis of L1CAM. This glycoprotein plays a major role in the development of the nervous system, and is involved in cancer development and is associated with metastases and poor prognosis. Two L1CAM isoforms are subject to endocytosis: isoform 1, described as a clathrin-mediated cargo; isoform 2, whose endocytosis has never been studied. Deciphering the molecular machinery of isoform 2 internalisation should contribute to a better understanding of its pathophysiological role. First, we demonstrated in our cellular context that both isoforms of L1CAM are mainly a clathrin-independent cargo, which was not expected for isoform 1. Second, the mechanism of L1CAM endocytosis is specifically mediated by the N-BAR domain protein endophilin-A3. Third, we discovered PSTPIP1, an F-BAR domain protein, as a novel actor in this endocytic process. Finally, we identified galectins as endocytic partners and negative regulators of L1CAM endocytosis. In summary, the interplay of the BAR proteins endophilin-A3 and PSTPIP1, and galectins fine tune the clathrin-independent endocytosis of L1CAM.

Re-Expression of Poly/Oligo-Sialylated Adhesion Molecules on the Surface of Tumor Cells Disrupts Their Interaction with Immune-Effector Cells and Contributes to Pathophysiological Immune Escape

Glycans linked to surface proteins are the most complex biological macromolecules that play an active role in various cellular mechanisms. This diversity is the basis of cell-cell interaction and communication, cell growth, cell migration, as well as co-stimulatory or inhibitory signaling. Our review describes the importance of neuraminic acid and its derivatives as recognition elements, which are located at the outermost positions of carbohydrate chains linked to specific glycoproteins or glycolipids. Tumor cells, especially from solid tumors, mask themselves by re-expression of hypersialylated neural cell adhesion molecule (NCAM), neuropilin-2 (NRP-2), or synaptic cell adhesion molecule 1 (SynCAM 1) in order to protect themselves against the cytotoxic attack of the also highly sialylated immune effector cells. More particularly, we focus on α-2,8-linked polysialic acid chains, which characterize carrier glycoproteins such as NCAM, NRP-2, or SynCam-1. This characteristic property correlates with an aggressive clinical phenotype and endows them with multiple roles in biological processes that underlie all steps of cancer progression, including regulation of cell-cell and/or cell-extracellular matrix interactions, as well as increased proliferation, migration, reduced apoptosis rate of tumor cells, angiogenesis, and metastasis. Specifically, re-expression of poly/oligo-sialylated adhesion molecules on the surface of tumor cells disrupts their interaction with immune-effector cells and contributes to pathophysiological immune escape. Further, sialylated glycoproteins induce immunoregulatory cytokines and growth factors through interactions with sialic acid-binding immunoglobulin-like lectins. We describe the processes, which modulate the interaction between sialylated carrier glycoproteins and their ligands, and illustrate that sialic acids could be targets of novel therapeutic strategies for treatment of cancer and immune diseases.

Immunohistochemical analysis of L1 cell adhesion molecule and high endothelial venules in breast cancer brain metastasis

BACKGROUND

The vasculature is a crucial factor in tumor development. Vascular co-option achieved by the L1 cell adhesion molecule (L1CAM) and lymphocyte recruitment inside tumors by high endothelial venules (HEVs) are important prognostic factors in primary breast cancer. Their status in breast cancer brain metastasis is unknown.

AIM OF THE STUDY

To explore the status of L1CAMs and HEVs in this tumor compartment.

MATERIAL AND METHODS

Thirty resected breast cancer brain metastases were immunohistochemically studied for L1CAM and MECA-79, an HEV marker. Clinicopathological factors were recorded.

RESULTS

Age at brain metastasis diagnosis ranged from 37 to 80 years (median 55). The time to brain metastasis development after primary tumor diagnosis ranged from 12 to 187 months (median 57). Median overall survival after brain metastasis diagnosis was 29 months. None of the tumors expressed the factors studied.

CONCLUSION

L1CAM and high endothelial venules are not found in breast cancer brain metastasis.

Wnt/β-Catenin Target Genes in Colon Cancer Metastasis: The Special Case of L1CAM

Simple Summary

The Wnt/β-catenin cell–cell signaling pathway is one of the most basic and highly conserved pathways for intercellular communications regulating key steps during development, differentiation, and cancer. In colorectal cancer (CRC), in particular, aberrant activation of the Wnt/β-catenin pathway is believed to be responsible for perpetuating the disease from the very early stages of cancer development. A large number of downstream target genes of β-catenin-T-cell factor (TCF), including oncogenes, were detected as regulators of CRC development. In this review, we will summarize studies mainly on one such target gene, the L1CAM (L1) cell adhesion receptor, that is selectively induced in invasive and metastatic CRC cells and in regenerating cells of the intestine following injury. We will describe studies on the genes activated when the levels of L1 are increased in CRC cells and their effectiveness in propagating CRC development. These downstream targets of L1-signaling can serve in diagnosis and may provide additional targets for CRC therapy.

Abstract

Cell adhesion to neighboring cells is a fundamental biological process in multicellular organisms that is required for tissue morphogenesis. A tight coordination between cell–cell adhesion, signaling, and gene expression is a characteristic feature of normal tissues. Changes, and often disruption of this coordination, are common during invasive and metastatic cancer development. The Wnt/β-catenin signaling pathway is an excellent model for studying the role of adhesion-mediated signaling in colorectal cancer (CRC) invasion and metastasis, because β-catenin has a dual role in the cell; it is a major adhesion linker of cadherin transmembrane receptors to the cytoskeleton and, in addition, it is also a key transducer of Wnt signaling to the nucleus, where it acts as a co-transcriptional activator of Wnt target genes. Hyperactivation of Wnt/β-catenin signaling is a common feature in the majority of CRC patients. We found that the neural cell adhesion receptor L1CAM (L1) is a target gene of β-catenin signaling and is induced in carcinoma cells of CRC patients, where it plays an important role in CRC metastasis. In this review, we will discuss studies on β-catenin target genes activated during CRC development (in particular, L1), the signaling pathways affected by L1, and the role of downstream target genes activated by L1 overexpression, especially those that are also part of the intestinal stem cell gene signature. As intestinal stem cells are highly regulated by Wnt signaling and are believed to also play major roles in CRC progression, unravelling the mechanisms underlying the regulation of these genes will shed light on both normal intestinal homeostasis and the development of invasive and metastatic CRC.

Role of Tissue Transglutaminase Catalytic and Guanosine Triphosphate-Binding Domains in Renal Cell Carcinoma Progression

Tissue transglutaminase (TG2) is a multifunctional protein that can act as a cross-linking enzyme, GTPase/ATPase, protein kinase, and protein disulfide isomerase. TG2 is involved in cell adhesion, migration, invasion, and growth, as well as epithelial-mesenchymal transition (EMT). Our previous findings indicate that the increased expression of TG2 in renal cell carcinoma (RCC) results in tumor metastasis with a significant decrease in disease- and cancer-specific survival outcome. Given the importance of the prometastatic activity of TG2 in RCC, in the present study, we aim to investigate the relative contribution of TG2's transamidase and guanosine triphosphate (GTP)-binding/GTPase activity in the cell migration, invasion, EMT, and cancer stemness of RCC. For this purpose, the mouse RCC cell line RenCa was transduced with wild-type-TG2 (wt-TG2), GTP-binding deficient-form TG2-R580A, transamidase-deficient form with low GTP-binding affinity TG2-C277S, and transamidase-inactive form TG2-W241A. Our results suggested that predominantly, GTP-binding activity of TG2 is responsible for cell migration and invasion. In addition, CD marker analysis and spheroid assay confirmed that GTP binding/GTPase activity of TG2 is important in the maintenance of mesenchymal character and the cancer stem cell profile. These findings support a prometastatic role for TG2 in RCC that is dependent on the GTP binding/GTPase activity of the enzyme.

L1 cell adhesion molecule (L1CAM) in stage IB cervical cancer: distinct expression in squamous cell carcinomas and adenocarcinomas

AIMS

L1 cell adhesion molecule (L1CAM) has been shown to be correlated with tumour progression, attributed to its possible association with epithelial-mesenchymal transition (EMT), characterised by the expression of vimentin and loss of e-cadherin. Herein, we investigate the associations between L1CAM and clinicopathological parameters, as well as the expression of vimentin and e-cadherin, in carcinomas restricted to the cervix.

METHODS

The study was retrospective observational and included 45 squamous cell carcinomas (63.4%) and 26 adenocarcinomas (36.6%) submitted to primary surgical treatment. Patient age, FIGO (International Federation of Gynecology and Obstetrics) stage, tumour size and follow-up were obtained from the medical records. All the slides were revised to evaluate histological differentiation, lymphovascular space invasion, depth of infiltration, disease-free cervical wall thickness, pattern of invasion front, Silva pattern (for adenocarcinomas) and the percentage of tumour-infiltrating lymphocytes. Tissue microarrays were constructed for immunohistochemical staining for L1CAM, e-cadherin and vimentin.

RESULTS

Adenocarcinomas were associated with lower disease-free and overall survival. L1CAM and vimentin expressions were more frequent among adenocarcinomas, although loss of e-cadherin expression was more common among squamous carcinomas. L1CAM expression was associated with larger tumours, vimentin expression and lower disease-free survival. No association was observed between the expression of either L1CAM or vimentin and loss of e-cadherin. High levels of tumour-infiltrating lymphocytes were more frequent in squamous cell carcinoma, high-grade tumours, destructive pattern at front of invasion and loss of e-cadherin expression.

CONCLUSIONS

Our results confirm the prognostic role of L1CAM in cervical carcinomas, but suggest a role for mechanisms other than EMT.

L1 Cell Adhesion Molecule in Cancer, a Systematic Review on Domain-Specific Functions

L1 cell adhesion molecule (L1CAM) is a glycoprotein involved in cancer development and is associated with metastases and poor prognosis. Cellular processing of L1CAM results in expression of either full-length or cleaved forms of the protein. The different forms of L1CAM may localize at the plasma membrane as a transmembrane protein, or in the intra- or extracellular environment as cleaved or exosomal forms. Here, we systematically analyze available literature that directly relates to L1CAM domains and associated signaling pathways in cancer. Specifically, we chart its domain-specific functions in relation to cancer progression, and outline pre-clinical assays used to assess L1CAM. It is found that full-length L1CAM has both intracellular and extracellular targets, including interactions with integrins, and linkage with ezrin. Cellular processing leading to proteolytic cleavage and/or exosome formation results in extracellular soluble forms of L1CAM that may act through similar mechanisms as compared to full-length L1CAM, such as integrin-dependent signals, but also through distinct mechanisms. We provide an algorithm to guide a step-wise analysis on L1CAM in clinical samples, to promote interpretation of domain-specific expression. This systematic review infers that L1CAM has an important role in cancer progression that can be attributed to domain-specific forms. Most studies focus on the full-length plasma membrane L1CAM, yet knowledge on the domain-specific forms is a prerequisite for selective targeting treatment.

L1 Cell Adhesion Molecule and Its Soluble Form sL1 Exhibit Poor Prognosis in Primary Breast Cancer Patients

INTRODUCTION

The L1 cell adhesion molecule (L1-CAM) and its soluble form sL1 play a prominent role in invasion and metastasis in several cancers. However, its association with breast cancer is still unclear.

PATIENTS AND METHODS

We analyzed L1-CAM expression and serum sL1 levels in cancer and para-carcinoma tissues from 162 consecutive patients with primary invasive breast cancer (PBC) using immunohistochemistry and an enzyme-linked immunosorbent assay, respectively. The serum sL1 levels were also examined in 38 patients with benign breast disease and 36 healthy controls.

RESULTS

L1-CAM was expressed more frequently in cancer tissues than in para-carcinoma tissues (24.1% vs. 5.6%; P < .001), and the mean sL1 levels were significantly greater in PBC than in those with benign breast disease and healthy controls (P = .027). Both L1-CAM⁺ expression and higher mean sL1 levels correlated significantly with larger tumor size, lymph node involvement, higher histologic grade, advanced TNM stage, and shorter disease-free survival for PBC patients. Moreover, higher mean sL1 levels were also significantly associated with estrogen receptor-α-negative expression, human epidermal growth factor receptor 2-positive (HER2⁺) expression, HER2-enriched and triple-negative molecular subtypes, and L1-CAM⁺ expression (P < .05). On multivariate analysis, larger tumor size, nodal involvement, HER2⁺, and higher sL1 levels (≥ 0.7 ng/mL) were independent factors associated with L1-CAM⁺ expression (P < .05). No association was found between L1-CAM expression or sL1 level with age, gender, histologic type, or expression of progesterone receptor, Ki-67, p53, or vascular endothelial growth factor C (P > .05).

CONCLUSION

These results indicate that L1-CAM and sL1 are elevated in PBC and both might affect the prognosis of PBC patients. In addition, sL1 might be a useful marker for screening and diagnosis.

Cell-cell adhesion: linking Wnt/β-catenin signaling with partial EMT and stemness traits in tumorigenesis

Changes in cell adhesion and motility are considered key elements in determining the development of invasive and metastatic tumors. Co-opting the epithelial-to-mesenchymal transition (EMT) process, which is known to occur during embryonic development, and the associated changes in cell adhesion properties in cancer cells are considered major routes for tumor progression. More recent in vivo studies in tumor tissues and circulating tumor cell clusters suggest a stepwise EMT process rather than an “all-or-none” transition during tumor progression. In this commentary, we addressed the molecular mechanisms underlying the changes in cell adhesion and motility and adhesion-mediated signaling and their relationships to the partial EMT states and the acquisition of stemness traits by cancer cells.

L1CAM further stratifies endometrial carcinoma patients with no specific molecular risk profile

Background

The newly developed Proactive Molecular Risk Classifier for Endometrial Cancer (ProMisE) has consistently been shown to be prognostically significant in endometrial carcinomas (EC). Recently, we and others have demonstrated L1 cell-adhesion molecule (L1CAM) to be a significant indicator of high-risk disease in EC. In the current study, it was our aim to determine the prognostic significance of aberrant L1CAM expression in ProMisE subgroups in a large, single centre, population-based EC cohort.

Methods

ProMisE (POLE; MMR-D; p53 wt/NSMP; p53 abn) classification results from a cohort of 452 EC were available for analysis. L1CAM expression was studied by immunohistochemistry on whole slides. Correlations between clinicopathological data and survival were calculated.

Results

Expression of L1CAM was most frequent in p53 abnormal tumours (80%). L1CAM status was predictive of worse outcome among tumours with no specific molecular profile (p53 wt/NSMP) (p < 0.0001). Among p53 wt/NSMP EC, L1CAM remained a significant prognosticator for disease-specific survival after multivariate analysis (p = 0.035).

Conclusion

L1CAM status was able to significantly stratify risk among tumours of the large p53 wt/NSMP ProMisE subgroup of EC. Furthermore, our study confirms a highly significant correlation between mutation-type p53 immunostaining and abnormal L1CAM expression in EC.

Neuroblastoma Origin and Therapeutic Targets for Immunotherapy

Neuroblastoma is a pediatric solid cancer of heterogeneous clinical behavior. The unique features of this type of cancer frequently hamper the process of determining clinical presentation and predicting therapy effectiveness. The tumor can spontaneously regress without treatment or actively develop and give rise to metastases despite aggressive multimodal therapy. In recent years, immunotherapy has become one of the most promising approaches to the treatment of neuroblastoma. Still, only one drug for targeted immunotherapy of neuroblastoma, chimeric monoclonal GD2-specific antibodies, is used in the clinic today, and its application has significant limitations. In this regard, the development of effective and safe GD2-targeted immunotherapies and analysis of other potential molecular targets for the treatment of neuroblastoma represents an important and topical task. The review summarizes biological characteristics of the origin and development of neuroblastoma and outlines molecular markers of neuroblastoma and modern immunotherapy approaches directed towards these markers.

The intestinal stem cell regulating gene ASCL2 is required for L1-mediated colon cancer progression

Aberrant Wnt/β-catenin signaling is a common event during human colorectal cancer (CRC) development. Previously, we characterized members of the L1 family of cell adhesion receptors as targets of β-catenin-LEF1/TCF transactivation that are expressed at the invasive CRC tissue edge. Overexpression of L1 in CRC cells confers enhanced motility, tumorigenesis and liver metastasis. We identified several downstream targets of L1-mediated signaling that are considered key intestinal stem cell signature genes. Here, we investigated the involvement of ASCL2, a Wnt target gene and key determinant of intestinal stem cell state, in L1-mediated CRC progression. In L1 overexpressing CRC cells we found an increase in ASCL2, a decrease in E-cadherin and accumulation of nuclear β-catenin, β-catenin-LEF1/TCF transactivation and target gene expression. The increase in ASCL2 by L1 overexpression enhanced ASCL2 target gene expression, conferred increased motility, tumorigenesis and metastasis, similar to L1 overexpression. Suppression of ASCL2 in cells expressing L1 blocked these tumorigenic properties. In human CRC tissue, ASCL2 was detected in the nuclei of cells at invasive areas of the tumor that also expressed L1. The results suggest that increased ASCL2 expression is a critical step in L1-mediated CRC progression.

Prognostic value and clinicopathologic characteristics of L1 cell adhesion molecule (L1CAM) in a large series of vulvar squamous cell carcinomas

Background

Vulvar cancer treatment is mostly curative, but also has high morbidity rates. In a search for markers that can identify patients at risk of metastases, we investigated the prognostic value of L1-cell adhesion molecule (L1CAM) in large series of vulvar squamous cell carcinomas (VSCCs). L1CAM promotes cell motility and is an emerging prognostic factor for metastasis in many cancer subtypes.

Results

L1CAM expression was observed at the invasive front or in spray-patterned parts of 17% of the tumours. L1CAM-positive tumours expressed vimentin more often, but L1CAM expression was not associated with TP53 or CTNNB1 mutations. Five-year survival was worse for patients with L1CAM expression (overall survival 46.1% vs 63.6%, P=.014, disease specific survival 63.8% vs 80.0%, P=.018). Multivariate analysis indicates L1CAM expression as an independent prognostic marker (HR 2.9, 95% CI 1.10–7.68). An in vitro spheroid invasion assay showed decreased invasion of L1CAM-expressing VSCC spindle cells after treatment with L1CAM-neutralising antibodies.

Materials and Methods

Paraffin-embedded tumour tissue from two cohorts (N=103 and 245) of primary VSCCs were stained for L1CAM, vimentin and E-cadherin. Patients of the first cohort were tested for human papilloma virus infection and sequenced for TP53 and CTNNB1 (β-catenin) mutations. The expression of L1CAM was correlated to clinical characteristics and patient survival.

Conclusion

This is the first study to show high L1CAM-expression at the infiltrating margin of VSCC's. L1CAM-expressing VSCCs had a significantly worse prognosis compared to L1CAM-negative tumours. The highest expression was observed in spindle-shaped cells, where it might be correlated to their invasive capacity.

L1 cell adhesion molecule (L1CAM) is a strong predictor for locoregional recurrences in cervical cancer

Background

L1 cell adhesion molecule (L1CAM) has been shown to be a prognostic marker in various cancer types, and has been suggested to play a role in epithelial mesenchymal transition (EMT). Here, we determined the prognostic significance of L1CAM in cervical cancer and its association with vimentin expression on tumor cells, indicative of EMT.

Methods

Formalin-fixed, paraffin-embedded primary tumor samples from 372 cervical cancer patients were collected for immunohistochemical analysis of L1CAM expression. In 109 FFPE specimens, the percentage of vimentin expressing tumor cells was determined by flow cytometry.

Results

Positive L1CAM expression (≥10% of tumor cells) was associated with disease-free survival, validated using RNAseq TCGA data. L1CAM expression was independently associated with locoregional recurrence-free survival (hazard ratio 2.62, 95% CI 1.33 – 5.17, P = 0.006), and strongly associated with percentage of vimentin expressing tumor cells (P = 0.003). Expression of both L1CAM and vimentin indicated a subgroup with the highest risk of recurrence (hazard ratio 3.15, 95% CI 1.25 – 7.92, P = 0.015).

Conclusion

L1CAM might be a promising new prognostic marker for locoregional recurrences in cervical cancer, and its association with vimentin expression suggests that L1CAM might affect tumor aggressiveness, possibly through EMT.

L1 increases adhesion-mediated proliferation and chemoresistance of retinoblastoma

Retinoblastoma is the most common intraocular cancer in children, affecting 1/20,000 live births. Currently, children with retinoblastoma were treated with chemotherapy using drugs such as carboplatin, vincristine, and etoposide. Unfortunately, if conventional treatment fails, the affected eyes should be removed to prevent extension into adjacent tissues and metastasis. This study is to investigate the roles of L1 in adhesion-mediated proliferation and chemoresistance of retinoblastoma. L1 was differentially expressed in 30 retinoblastoma tissues and 2 retinoblastoma cell lines. Furthermore, the proportions of L1-positive cells in retinoblastoma tumors were negatively linked with the number of Flexner-Wintersteiner rosettes, a characteristic of differentiated retinoblastoma tumors, in each tumor sample. Following in vitro experiments using L1-deleted and -overexpressing cells showed that L1 increased adhesion-mediated proliferation of retinoblastoma cells via regulation of cell cycle-associated proteins with modulation of Akt, extracellular signal-regulated kinase, and p38 pathways. In addition, L1 increased resistance against carboplatin, vincristine, and esoposide through up-regulation of apoptosis- and multidrug resistance-related genes. In vivo tumor formation and chemoresistance were also positively linked with the levels of L1 in an orthotopic transplantation model in mice. In this manner, L1 increases adhesion-mediated proliferation and chemoresistance of retinoblastoma. Targeted therapy to L1 might be effective in the treatment of retinoblastoma tumors, especially which rapidly proliferate and demonstrate resistance to conventional chemotherapeutic drugs.

Copy number variation, increased gene expression, and molecular mechanisms of neurofascin in lung cancer

Metastasis and cell adhesion are key aspects of cancer progression. Neurofascin (NFASC) is a member of the immunoglobulin superfamily of adhesion molecules and, while studies on NFASC are inadequate, other members have been indicated pivotal roles in cancer progression and metastasis. This study aimed at increasing the knowledge on the involvement of adhesion molecules in lung cancer progression by studying the regulation and role of NFASC in non‐small cell lung cancer (NSCLC). Here, copy number variations in the NFASC gene were analyzed in tumor and non‐tumorous lung tissues of 204 NSCLC patients. Frequent gene amplifications (OR = 4.50, 95%CI: 2.27‐8.92, P ≤ 0.001) and increased expression of NFASC (P = 0.034) were identified in tumors of NSCLC patients. Furthermore, molecular mechanisms of NFASC in lung cancer progression were evaluated by investigating the effects of NFASC silencing on cell proliferation, viability, migration, and invasion using siRNA technology in four NSCLC cell lines. Silencing of NFASC did not affect cell proliferation or viability but rather decreased NSCLC cell migration (P ≤ 0.001) and led to morphological changes, rearrangements in the actin cytoskeleton and changes in F‐actin networks in migrating NSCLC cell lines. This study is the first to report frequent copy number gain and increased expression of NFASC in NSCLC. Moreover, these data suggest that NFASC is a novel regulator of NSCLC cell motility and support a role of NFASC in the regulation of NSCLC progression.

RON and c-Met facilitate metastasis through the ERK signaling pathway in prostate cancer cells

Prostate cancer (PCa) is a metastatic malignant cancer driven by complex pathological mechanisms and characterized by poor long-term prognosis. Metastasis is the main cause of death of PCa patients, yet the molecular mechanisms of this process are poorly understood. In the present study, positive co-expression of RON and c-Met was observed in human clinical PCa tissues (biopsy material), as detected by immunohistochemical staining and quantitative real-time PCR. We investigated this further in PCa cells, demonstrating that the inhibition of RON and c-Met with foretinib (GSK1363089) suppressed metastasis and promoted the reversal of the epithelial-to-mesenchymal transition (EMT) in PCa cells. Furthermore, the invasion and migration of PCa cells were enhanced by the exogenous activation of RON with MSP and c-Met with HGF, whereas silencing of RON and c-Met attenuated the invasion and metastasis of the PCa cells. Our data also demonstrated that HGF/c-Met, but not the MSP-RON signaling pathway may be the dominant mechanism for PCa EMT. We further revealed that RON and c-Met facilitate metastasis via ERK1/2 signaling. These findings indicate that RON and c-Met facilitate metastasis through ERK1/2 signaling and that targeting RON and c-Met with foretinib may be an attractive therapeutic option for suppressing PCa metastasis.

The role of epithelial-mesenchymal transition drivers ZEB1 and ZEB2 in mediating docetaxel-resistant prostate cancer

Docetaxel is the main treatment for advanced castration‐resistant prostate cancer; however, resistance eventually occurs. The development of intratumoral drug‐resistant subpopulations possessing a cancer stem cell (CSC) morphology is an emerging mechanism of docetaxel resistance, a process driven by epithelial–mesenchymal transition (EMT). This study characterised EMT in docetaxel‐resistant sublines through increased invasion, MMP‐1 production and ZEB1 and ZEB2 expression. We also present evidence for differential EMT across PC‐3 and DU145 in vitro resistance models as characterised by differential migration, cell colony scattering and susceptibility to the CSC inhibitor salinomycin. siRNA manipulation of ZEB1 and ZEB2 in PC‐3 and DU145 docetaxel‐resistant sublines identified ZEB1, through its transcriptional repression of E‐cadherin, to be a driver of both EMT and docetaxel resistance. The clinical relevance of ZEB1 was also determined through immunohistochemical tissue microarray assessment, revealing significantly increased ZEB1 expression in prostate tumours following docetaxel treatment. This study presents evidence for a role of ZEB1, through its transcriptional repression of E‐cadherin to be a driver of both EMT and docetaxel resistance in docetaxel‐resistant prostate cancer. In addition, this study highlights the heterogeneity of prostate cancer and in turn emphasises the complexity of the clinical management of docetaxel‐resistant prostate cancer.

The sL1CAM in sera of patients with endometrial and ovarian cancers

PURPOSE

L1CAM is a cell adhesion molecule suspected to play an important role in carcinogenesis. The objective of the study was to evaluate the level of soluble L1CAM in the sera of patients with endometrial and ovarian carcinomas and verify the feasibility of the sL1CAM as a marker of these carcinomas.

METHODS

35 endometrial and 18 ovarian cancer patients were enrolled in the study. 43 patients with benign gynecological conditions constituted a control group. The sL1CAM serum level was measured with ELISA test in each patient and it was referred to the data from the surgical staging of the cancers.

RESULTS

The sL1CAM serum level was significantly lower in patients with endometrial cancer than in healthy women and slightly lower in the ovarian cancer group than in the control group. In the endometrial cancer group there was no correlation between sL1CAM concentration and cancer histopathology, stage or grade. sL1CAM concentration positively correlated with ovarian cancer stage and (not significantly) with grade.

CONCLUSIONS

Despite the increasing data about the possible role of L1CAM as a strong prognostic factor of poor outcome in many cancers, we did not find evidence supporting the use of sL1CAM as a marker of endometrial or ovarian cancers.

Modes of invasion during tumour dissemination

Cancer cell migration and invasion underlie metastatic dissemination, one of the major problems in cancer. Tumour cells exhibit a striking variety of invasion strategies. Importantly, cancer cells can switch between invasion modes in order to cope with challenging environments. This ability to switch migratory modes or plasticity highlights the challenges behind antimetastasis therapy design. In this Review, we present current knowledge on different tumour invasion strategies, the determinants controlling plasticity and arising therapeutic opportunities. We propose that targeting master regulators controlling plasticity is needed to hinder tumour dissemination and metastasis.

L1CAM in the Early Enteric and Urogenital System

L1 cell adhesion molecule (L1CAM) is a transmembrane molecule belonging to the L1 protein family. It has shown to be a key player in axonal guidance in the course of neuronal development. Furthermore, L1CAM is also crucial for the establishment of the enteric and urogenital organs and is aberrantly expressed in cancer originating in these organs. Carcinogenesis and embryogenesis follow a lot of similar molecular pathways, but unfortunately, comprehensive data on L1CAM expression and localization in human developing organs are lacking so far. In the present study we, therefore, examined the spatiotemporal distribution of L1CAM in the early human fetal period (weeks 8-12 of gestation) by means of immunohistochemistry and in situ hybridization (ISH). In the epithelia of the gastrointestinal organs, L1CAM localization cannot be observed in the examined stages most likely due to their advanced polarization and differentiation. Despite these results, our ISH data indicate weak L1CAM expression, but only in few epithelial cells. The genital tracts, however, are distinctly L1CAM positive throughout the entire fetal period. We, therefore, conclude that in embryogenesis L1CAM is crucial for further differentiation of epithelia.

L1CAM expression in endometrial carcinomas: an ENITEC collaboration study

Background:

Identification of aggressive endometrioid endometrial carcinomas (EECs) and non-endometrioid carcinomas (NEECs) is essential to improve outcome. L1 cell adhesion molecule (L1CAM) expression is a strong prognostic marker in stage I EECs, but less is known about L1CAM expression in advanced-stage EECs and NEECs. This study analyses L1CAM expression in a clinically representative cohort of endometrial carcinomas.

Methods:

The expression of L1CAM was immunohistochemically determined in 1199 endometrial carcinomas, treated at one of the European Network for Individualized Treatment of Endometrial Cancer (ENITEC) centres. Staining was considered positive when >10% of the tumour cells expressed L1CAM. The association between L1CAM expression and several clincopathological characteristics and disease outcome was calculated.

Results:

In all, L1CAM was expressed in 10% of the 935 stage I EECs, 18% of the 160 advanced stage EECs, and 75% of the 104 NEECs. The expression of L1CAM was associated with advanced stage, nodal involvement, high tumour grade, non-endometrioid histology, lymphovascular space invasion, and distant recurrences in all cases, and with reduced survival in the EECs, but not in the NEECs.

Conclusions:

The expression of L1CAM is a strong predictor of poor outcome in EECs, but not NEECs. It is strongly associated with non-endometrioid histology and distant spread, and could improve the postoperative selection of high-risk endometrial carcinomas. The value of L1CAM expression in the preoperative selection of high-risk endometrial carcinomas should be studied.

The Wnt Target Gene L1 in Colon Cancer Invasion and Metastasis

The Wnt-β-catenin signaling pathway is highly conserved during evolution and determines normal tissue homeostasis. Hyperactivation of Wnt-β-catenin signaling is a characteristic feature of colorectal cancer (CRC) development. β-catenin is a major transducer of the Wnt signal from the cytoplasm into the nucleus where it acts as a co-transcriptional activator of β-catenin-TCF target genes. β-catenin is also required for linking cadherin type cell-cell adhesion receptors to the cytoskeleton, and consequently Wnt-β-catenin signaling is an attractive system for investigating the role of adhesion-mediated signaling in both normal intestinal tissue homeostasis and CRC development. In this review, we summarize our studies on one Wnt-β-catenin target gene, L1, a member of the immunoglobulin-like cell adhesion transmembrane receptor family. We describe the mechanisms of L1-mediated signaling in CRC cells, its exclusive localization in invasive areas of CRC tissue, and its ability to increase cell motility and confer metastasis to the liver. We discuss the activation (by L1) of genes via an ezrin-NF-κB pathway and the induction of genes also found in the intestinal stem cell signature. By studying L1 (adhesion)-mediated signaling, we expect to learn about mechanisms regulating both normal intestinal homeostasis and CRC development.

L1 cell adhesion molecule as a therapeutic target in cancer

L1 cell adhesion molecule (L1CAM) is the prototype member of the L1-family of closely related neural adhesion molecules. L1CAM is differentially expressed in the normal nervous system as well as pathological tissues and displays a wide range of biological activities. In human malignancies, L1CAM plays a vital role in tumor growth, invasion and metastasis. Recently, increasing evidence has suggested that L1CAM exerts a variety of functions at different steps of tumor progression through a series of signaling pathways. In addition, L1CAM has been identified as a promising target for cancer therapy by using synthetic and natural inhibitors. In this review, we provide an up-to-date overview of the role of L1CAM involved in cancers and the rationale for L1CAM as a novel molecular target for cancer therapy.

Expression and prognostic significance of contactin 1 in human hepatocellular carcinoma

Background

CNTN1, a member of the CNTN family of neural cell-recognition molecules, is involved in tumor invasion and metastasis. Although the expression of CNTN1 has been reported in several human malignancies, the expression of CNTN1 in hepatocellular carcinoma (HCC) and its correlation with prognosis remain unclear. The aim of this study was to evaluate the expression of CNTN1 and determine the clinicopathological parameters and prognostic value of CNTN1 in HCC patients.

Materials and methods

Quantitative real-time polymerase chain-reaction and Western blotting assays were performed to assess messenger RNA and protein levels of CNTN1 in 20 matched HCC specimens. The clinical and prognostic significance of CNTN1 in 90 cases of HCC was determined by immunohistochemistry.

Results

CNTN1 expression was higher in HCC compared to the expression found in adjacent tissues at both messenger RNA and protein levels (P<0.01). Notably, immunohistochemical results revealed that CNTN1 expression was significantly higher in HCC compared to adjacent tissues (54.4% vs 12.2%, P=0.01). Furthermore, positive CNTN1 expression was associated with tumor size, tumor capsulae, status of metastasis, and tumor–node–metastasis stage. Kaplan–Meier survival analysis showed that high CNTN1 was correlated with reduced overall survival (OS) rate (P<0.001) and disease-free survival (DFS) rate (P=0.001). Multivariate analysis identified CNTN1 as an independent poor prognostic factor of OS and DFS in HCC patients (P=0.007 and P=0.002, respectively).

Conclusion

Our results suggest that CNTN1 could play an important role in HCC and serve as an independent unfavorable prognostic factor for OS and DFS and a potential therapeutic target for HCC.

Roles of contactin-1 in solid tumors

The neural cell adhesion molecule contactin-1 (CNTN1), first identified as a member of the contactin subpopulation of the immunoglobulin superfamily, is associated with many other cell surface proteins expressed on a variety of neurocytes, contributing to their functions and maturation. It has been recently found that the abnormal expression of CNTN1 has a close correlation with tumor initiation, development, invasiveness, metastasis and prognosis. The acquired metastatic ability of malignant tumors is caused by a population of cancer cells with the capacities of invasiveness, metastasis, adherence and proliferation, in which abnormal gene expression may play an important role. This review focuses on the current advances in research of CNTN1 in the nerve system, and mainly in the malignant tumors, with an aim to provide new clues to clinical prevention, diagnosis and treatment of these malignancies.

Interplay between microRNAs and WNT/β-catenin signalling pathway regulates epithelial-mesenchymal transition in cancer

The WNT/β-catenin signalling implies its significance in maintaining an epithelial cell phenotype, proper cell-cell junctions, and tissue homeostasis. Dysregulation of the members of this pathway involves in the development of cancer and an epithelial-mesenchymal transition (EMT) required for metastasis. Loss of E-cadherin is the major contributor to an EMT process and is largely influenced by the WNT/β-catenin signalling. An E-cadherin/β-catenin complex maintains epithelial integrity and disturbance of this complex and WNT/β-catenin pathway will ultimately lead to the nuclear translocation of β-catenin and transcription of EMT-promoting genes. WNT/β-catenin signalling is controlled by microRNAs (miRNAs), several of which are either up- or downregulated during EMT. The strong association between the expression of the WNT signalling components with miRNAs in the initiation and achievement of an EMT phenotype is suggestive of introducing these miRNAs as therapeutic targets against metastatic tumours. Therefore, this review aims to describe these putative miRNAs in altering the WNT/β-catenin signalling in EMT, and whether targeting them is a useful therapeutic option for human invasive tumours.

Slug-dependent upregulation of L1CAM is responsible for the increased invasion potential of pancreatic cancer cells following long-term 5-FU treatment

Background

Pancreatic adenocarcinoma is a lethal disease with 5-year survival of less than 5%. 5-fluorouracil (5-FU) is a principal first-line therapy, but treatment only extends survival modestly and is seldom curative. Drug resistance and disease recurrence is typical and there is a pressing need to overcome this. To investigate acquired 5-FU resistance in pancreatic adenocarcinoma, we established chemoresistant monoclonal cell lines from the Panc 03.27 cell line by long-term exposure to increasing doses of 5-FU.

Results

5-FU-resistant cell lines exhibited increased expression of markers associated with multidrug resistance explaining their reduced sensitivity to 5-FU. In addition, 5-FU-resistant cell lines showed alterations typical for an epithelial-to-mesenchymal transition (EMT), including upregulation of mesenchymal markers and increased invasiveness. Microarray analysis revealed the L1CAM pathway as one of the most upregulated pathways in the chemoresistant clones, and a significant upregulation of L1CAM was seen on the RNA and protein level. In pancreatic cancer, expression of L1CAM is associated with a chemoresistant and migratory phenotype. Using esiRNA targeting L1CAM, or by blocking the extracellular part of L1CAM with antibodies, we show that the increased invasiveness observed in the chemoresistant cells functionally depends on L1CAM. Using esiRNA targeting β-catenin and/or Slug, we demonstrate that in the chemoresistant cell lines, L1CAM expression depends on Slug rather than β-catenin.

Conclusion

Our findings establish Slug-induced L1CAM expression as a mediator of a chemoresistant and migratory phenotype in pancreatic adenocarcinoma cells.

Single chain fragment variable antibodies developed by using as target the 3rd fibronectin type III homologous repeat fragment of human neural cell adhesion molecule L1 promote cell migration and neuritogenesis

L1CAM plays important roles during ontogeny, including promotion of neuronal cell migration and neuritogenesis, and stimulation of axonal outgrowth, fasciculation and myelination. These functions are at least partially exerted through a 16-mer amino acid sequence in the third fibronectin type III-like repeat of L1, which associates with several interaction partners, including integrins, other adhesion molecules and growth factor receptors. Here, using the Tomlinson I library for phage display, we obtained two single-chain variable fragment antibodies (scFvs) against this peptide sequence of human L1, hereafter called H3 peptide. Both scFvs recognize the H3 peptide and the extracellular domain of L1, as tested by enzyme-linked immunosorbent assay (ELISA), Western blot analysis and immunofluorescence staining of L1 expresssing cells. Furthermore, both scFvs reduce U-87 MG cell adhesion to fibronectin, while stimulating cell migration. Application of scFvs to human neuroblastoma SK-N-SH cells promote process outgrowth. Similar to triggering of endogenous L1 functions at the cell surface, both scFvs activate the signal transducers Erk and Src in these cells. Our results indicate that scFvs against a functionally pivotal domain in L1 trigger its regeneration-beneficial functions in vitro, encouraging thoughts on therapy of neurodegenerative diseases in the hope to ameliorate human nervous system diseases.

Engineered N-cadherin and L1 biomimetic substrates concertedly promote neuronal differentiation, neurite extension and neuroprotection of human neural stem cells

We investigated the design of neurotrophic biomaterial constructs for human neural stem cells, guided by neural developmental cues of N-cadherin and L1 adhesion molecules. Polymer substrates fabricated either as two-dimensional (2-D) films or three-dimensional (3-D) microfibrous scaffolds were functionalized with fusion chimeras of N-cadherin-Fc alone and in combination with L1-Fc, and the effects on differentiation, neurite extension and survival of H9 human-embryonic-stem-cell-derived neural stem cells (H9-NSCs) were quantified. Combinations of N-cadherin and L1-Fc co-operatively enhanced neuronal differentiation profiles, indicating the critical nature of the two complementary developmental cues. Notably, substrates presenting low levels of N-cadherin-Fc concentrations, combined with proportionately higher L1-Fc concentration, most enhanced neurite outgrowth and the degree of MAP2+ and neurofilament-M+ H9-NSCs. Low N-cadherin-Fc alone promoted improved cell survival following oxidative stress, compared to higher concentrations of N-cadherin-Fc alone or combinations with L1-Fc. Pharmacological and antibody blockage studies revealed that substrates presenting low levels of N-cadherin are functionally competent so long as they elicit a threshold signal mediated by homophilic N-cadherin and fibroblast growth factor signaling. Overall, these studies highlight the ability of optimal combinations of N-cadherin and L1 to recapitulate a "neurotrophic" microenvironment that enhances human neural stem cell differentiation and neurite outgrowth. Additionally, 3-D fibrous scaffolds presenting low N-cadherin-Fc further enhanced the survival of H9-NSCs compared to equivalent 2-D films. This indicates that similar biofunctionalization approaches based on N-cadherin and L1 can be translated to 3-D "transplantable" scaffolds with enhanced neurotrophic behaviors. Thus, the insights from this study have fundamental and translational impacts for neural-stem-cell-based regenerative medicine.

Endothelial deficiency of L1 reduces tumor angiogenesis and promotes vessel normalization

While tumor blood vessels share many characteristics with normal vasculature, they also exhibit morphological and functional aberrancies. For example, the neural adhesion molecule L1, which mediates neurite outgrowth, fasciculation, and pathfinding, is expressed on tumor vasculature. Here, using an orthotopic mouse model of pancreatic carcinoma, we evaluated L1 functionality in cancer vessels. Tumor-bearing mice specifically lacking L1 in endothelial cells or treated with anti-L1 antibodies exhibited decreased angiogenesis and improved vascular stabilization, leading to reduced tumor growth and metastasis. In line with these dramatic effects of L1 on tumor vasculature, the ectopic expression of L1 in cultured endothelial cells (ECs) promoted phenotypical and functional alterations, including proliferation, migration, tubulogenesis, enhanced vascular permeability, and endothelial-to-mesenchymal transition. L1 induced global changes in the EC transcriptome, altering several regulatory networks that underlie endothelial pathophysiology, including JAK/STAT-mediated pathways. In particular, L1 induced IL-6-mediated STAT3 phosphorylation, and inhibition of the IL-6/JAK/STAT signaling axis prevented L1-induced EC proliferation and migration. Evaluation of patient samples revealed that, compared with that in noncancerous tissue, L1 expression is specifically enhanced in blood vessels of human pancreatic carcinomas and in vessels of other tumor types. Together, these data indicate that endothelial L1 orchestrates multiple cancer vessel functions and represents a potential target for tumor vascular-specific therapies.

CD133 expression correlates with membrane beta-catenin and E-cadherin loss from human hair follicle placodes during morphogenesis

Genetic studies suggest that the major events of human hair follicle development are similar to those in mice, but detailed analyses of this process are lacking. In mice, hair follicle placode ‘budding’ is initiated by invagination of Wnt-induced epithelium into the underlying mesenchyme. Modification of adherens junctions is clearly required for budding. Snail-mediated downregulation of adherens junction component E-cadherin is important for placode budding in mice. Beta-catenin, another adherens junction component, has been more difficult to study due to its essential functions in Wnt signaling, a prerequisite for hair follicle placode induction. Here, we show that a subset of human invaginating hair placode cells expresses the stem cell marker CD133 during early morphogenesis. CD133 associates with membrane beta-catenin in early placodes and its continued expression correlates with loss of beta-catenin and E-cadherin from the cell membrane at a time when E-cadherin transcriptional repressors Snail and Slug are not implicated. Stabilization of CD133 via anti-CD133 antibody treatment of human fetal scalp explants depresses beta-catenin and E-cadherin membrane localization. We discuss this unique correlation and suggest a hypothetical model whereby CD133 promotes morphogenesis in early hair follicle placodes through the localized removal of membrane beta-catenin proteins and subsequent adherens junction dissolution.

Quantitative proteomics reveals ER-α involvement in CD146-induced epithelial-mesenchymal transition in breast cancer cells

The cell adhesion molecule CD146 is a novel inducer of epithelial-mesenchymal transition (EMT), which was associated with triple-negative breast cancer (TNBC). To gain insights into the complex networks that mediate CD146-induced EMT in breast cancers, we conducted a triple Stable Isotope Labeling with Amino Acids in Cell Culture (SILAC), to analyze whole cell protein profiles of MCF-7 cells that had undergone gradual EMT upon CD146 expression from moderate to high levels. In this study, we identified 2293 proteins in total, of which 103 exhibited changes in protein abundance that correlated with CD146 expression levels, revealing extensive morphological and biochemical changes associated with EMT. Ingenuity Pathway Analysis (IPA) showed that estrogen receptor (ER) was the most significantly inhibited transcription regulator during CD146-induced EMT. Functional assays further revealed that ER-α expression was repressed in cells undergoing CD146-induced EMT, whereas re-expression of ER-α abolished their migratory and invasive behavior. Lastly, we found that ER-α mediated its effects on CD146-induced EMT via repression of the key EMT transcriptional factor Slug. Our study revealed the molecular details of the complex signaling networks during CD146-induced EMT, and provided important clues for future exploration of the mechanisms underlying the association between CD146 and TNBC as observed in the clinic.

BIOLOGICAL SIGNIFICANCE

This study used a proteomics screen to reveal molecular changes mediated by CD146-induced epithelial-mesenchymal transition (EMT) in breast cancer cells. Estrogen receptor (ER) was found to be the most significantly inhibited transcription regulator, which mediated its effects on CD146-induced EMT via repression of the transcriptional factor Slug. Elucidation of protein interaction networks and signal networks generated from 103 significantly changed proteins would facilitate future investigation into the mechanisms underlying CD146 induced-EMT in breast cancers.

Downregulation of L1CAM inhibits proliferation, invasion and arrests cell cycle progression in pancreatic cancer cells in vitro

The aim of the present study was to establish the effect of silencing L1 cell adhesion molecule (L1CAM) on the proliferation, invasion, cell cycle progression and apoptosis of pancreatic cancer cells, and to determine the potential molecular mechanisms that are involved. The human Capan-2 pancreatic cancer cell line was infected with lentivirus-mediated short hairpin RNA (shRNA) to target L1CAM. Cell proliferation and invasion were analyzed using cell counting kit-8 and Transwell assays, respectively, and cell cycle progression and apoptosis were analyzed using flow cytometry. L1CAM protein expression in Capan-2 cells decreased following shRNA-L1CAM infection. Furthermore, knockdown of L1CAM significantly inhibited cell proliferation and reduced the number of invasive cells, while increasing the percentage of cells in the G0/G1 phase (P<0.05). However, the effect on apoptosis was not identified to be statistically significant. In addition, L1CAM silencing may induce activation of p38/extracellular signal regulated kinase 1/2. Downregulation of L1CAM may inhibit proliferation, invasion and arrests cell cycle progression in pancreatic cancer via p38/ERK1/2 signal pathway, and therefore, L1CAM may serve as a potential target for gene therapy in pancreatic cancer.

Overexpression of L1CAM is associated with tumor progression and prognosis via ERK signaling in gastric cancer

BACKGROUND

L1 cell adhesion molecule (L1CAM), which belongs to the immunoglobulin superfamily, has recently been observed in a variety of human malignancies. However, its clinical implication in gastric cancer remains unclear. The aim of this study was to explore the role of L1CAM in gastric cancer and to analyze its correlation with tumor progression and prognosis.

METHODS

L1CAM expression was measured in human gastric cancer cell lines and knockdown was conducted using siRNA. Cell proliferation, invasion and migration ability was assessed in vitro. The downstream pathway of L1CAM was explored by western blot analysis. L1CAM expression was measured in 112 pairs of human gastric cancer and adjacent noncancerous tissues using real-time quantitative RT-PCR, and the correlation with clinicopathological features and prognosis was analyzed.

RESULTS

L1CAM downregulation by siRNA significantly decreased cell proliferation, migration, and invasion in gastric cancer cell lines. Phosphorylated ERK levels began to decline more rapidly in L1CAM knockdown cells compared with parental cells. L1CAM overexpression was significantly correlated with local tumor cell growth (P = 0.041), distant metastasis (P = 0.047), and tumor stage (P = 0.031). The overall survival in patients with high L1CAM expression was significantly shorter than that of patients with low L1CAM expression (P = 0.02).

CONCLUSIONS

L1CAM overexpression may be a critical prognostic factor in patients with gastric cancer, and was strongly associated with tumor proliferation, migration, and invasion through the ERK pathway. L1CAM might be an attractive therapeutic molecular target for the treatment of gastric cancer patients.

Tetraspanin18 is a FoxD3-responsive antagonist of cranial neural crest epithelial-to-mesenchymal transition that maintains cadherin-6B protein

During epithelial-to-mesenchymal transition (EMT), tightly associated, polarized epithelial cells become individual mesenchymal cells capable of migrating. Here, we investigate the role of the transmembrane protein tetraspanin18 (Tspan18) in chick cranial neural crest EMT. Tspan18 mRNA is expressed in premigratory cranial neural crest cells, but is absent from actively migrating neural crest cells. Tspan18 knockdown leads to a concomitant loss of cadherin-6B (Cad6B) protein, whereas Cad6B protein persists when Tspan18 expression is extended. The temporal profile of Cad6B mRNA downregulation is unaffected in these embryos, which indicates that Tspan18 maintains Cad6B protein levels and reveals that Cad6B is regulated by post-translational mechanisms. Although downregulation of Tspan18 is necessary, it is not sufficient for neural crest migration: the timing of neural crest emigration, basal lamina breakdown and Cad7 upregulation proceed normally in Tspan18-deficient cells. This emphasizes the need for coordinated transcriptional and post-translational regulation of Cad6B during EMT and illustrates that Tspan18-antagonized remodeling of cell-cell adhesions is only one step in preparation for cranial neural crest migration. Unlike Cad6B, which is transcriptionally repressed by Snail2, Tspan18 expression is downstream of the winged-helix transcription factor FoxD3, providing a new transcriptional input into cranial neural crest EMT. Together, our data reveal post-translational regulation of Cad6B protein levels by Tspan18 that must be relieved by a FoxD3-dependent mechanism in order for cranial neural crest cells to migrate. These results offer new insight into the molecular mechanisms of cranial neural crest EMT and expand our understanding of tetraspanin function relevant to metastasis.

Alternatively spliced protein arginine methyltransferase 1 isoform PRMT1v2 promotes the survival and invasiveness of breast cancer cells

Protein arginine methylation is catalyzed by protein arginine methyltransferases (PRMTs) and plays an important role in many cellular processes. Aberrant PRMT expression has been observed in several common cancer types; however, their precise contribution to the cell transformation process is not well understood. We previously reported that the PRMT1 gene generates several alternatively spliced isoforms, and our initial biochemical characterization of these isoforms revealed that they exhibit distinct substrate specificity and subcellular localization. We focus here on the PRMT1v2 isoform, which is the only predominantly cytoplasmic isoform, and we have found that its relative expression is increased in breast cancer cell lines and tumors. Specific depletion of PRMT1v2 using RNA interference caused a significant decrease in cancer cell survival due to an induction of apoptosis. Furthermore, depletion of PRMT1v2 in an aggressive cancer cell line significantly decreased cell invasion. We also demonstrate that PRMT1v2 overexpression in a non-aggressive cancer cell line was sufficient to render them more invasive. Importantly, this novel activity is specific to PRMT1v2, as overexpression of other isoforms did not enhance invasion. Moreover, this activity requires both proper subcellular localization and methylase activity. Lastly, PRMT1v2 overexpression altered cell morphology and reduced cell-cell adhesion, a phenomenon that we convincingly linked with reduced β-catenin protein expression. Overall, we demonstrate a specific role for PRMT1v2 in breast cancer cell survival and invasion, underscoring the importance of identifying and characterizing the distinct functional differences between PRMT1 isoforms.

Inhibitory effects of calcium against intestinal cancer in human colon cancer cells and Apc(Min/+) mice

The aim of the study was to investigate the inhibitory effects of calcium against intestinal cancer in vitro and in vivo. We first investigated the effects of calcium treatment in HCT116 and HT29 human colon cancer cells. At the concentration range of 0.8-2.4 mM, calcium significantly inhibited cell growth (by 9-29%), attachment (by 12-26%), invasion (by 15-31%), and migration (by 19-61%). An immunofluorescence microscope analysis showed that the treatment with calcium (1.6 mM) for 24 h increased plasma membrane β-catenin but decreased nuclear β-catenin levels in HT29 cells. We then investigated the effect of dietary calcium on intestinal tumorigenesis in Apc^Min/+ mice. Mice received dietary treatment starting at 6 weeks of age for the consecutive 8 weeks. The basal control diet contained high-fat (20% mixed lipids by weight) and low-calcium (1.4 mg/g diet) to mimic the average Western diet, while the treatment diet contained an enriched level of calcium (5.2 mg calcium/g diet). The dietary calcium treatment decreased the total number of small intestinal tumors (by 31.4%; P < 0.05). The largest decrease was in tumors which were ≥ 2 mm in diameter, showing a 75.6% inhibition in the small intestinal tumor multiplicity (P < 0.001). Immunohistochemical analysis showed significantly reduced nuclear staining of β-catenin (expressed as nuclear positivity), but increased plasma membrane staining of β-catenin, in the adenomas from the calcium-treated groups in comparison to those from the control group (P < 0.001). These results demonstrate intestinal cancer inhibitory effects of calcium both in human colon cancer cells and Apc^Min/+ mice. The decreased β-catenin nuclear localization caused by the calcium treatment may contribute to the inhibitory action.

SIRT1 induces EMT by cooperating with EMT transcription factors and enhances prostate cancer cell migration and metastasis

The epithelial-to-mesenchymal transition (EMT) is a crucial program for the invasion and metastasis of epithelial tumors that involves loss of cell-cell adhesion and increased cell mobility; however, mechanisms underlying this transition are not fully elucidated. Here, we propose a novel mechanism through which the nicotinamide adenine dinucleotide-dependent histone deacetylase SIRT1 regulates EMT in prostate cancer cells through cooperation with the EMT inducing transcription factor ZEB1. We found that forced expression of SIRT1 in non-transformed PZ-HPV-7 prostate epithelial cells disrupts the epithelial morphology concomitant with decreased expression of the epithelial marker, E-cadherin, and increased expression of mesenchymal markers. In contrast, silencing SIRT1 in metastatic prostate tumor cells restores cell-cell adhesion and induces a shift toward an epithelial morphology concomitant with increased expression of E-cadherin and decreased expression of mesenchymal markers. We also found that SIRT1 has a physiologically relevant role in endogenous EMT induced by EGF signaling in prostate cancer cells. We propose that the regulation of EMT by SIRT1 involves modulation of, and cooperation with, the EMT inducing transcription factor ZEB1. Specifically, we show that SIRT1 silencing reduces expression of ZEB1 and that SIRT1 is recruited to the E-cadherin proximal promoter by ZEB1 to deacetylate histone H3 and to reduce binding of RNA polymerase II, ultimately suppressing E-cadherin transcription. We thus identify a necessary role for ZEB1 in SIRT1-mediated EMT. Finally, we show that reduction of SIRT1 decreases prostate cancer cell migration in vitro and metastasis in vivo in immunodeficient mice, which is largely independent of any general effects of SIRT1 on prostate cancer growth and survival. We therefore identify SIRT1 as a positive regulator of EMT and metastatic growth of prostate cancer cells and our findings implicate overexpressed SIRT1 as a potential therapeutic target to reverse EMT and to prevent prostate cancer progression.

Activation of the PTHRP/adenylate cyclase pathway promotes differentiation of rat XEN cells into parietal endoderm, whereas Wnt/β-catenin signaling promotes differentiation into visceral endoderm

During early mammalian development, primitive endoderm (PrE) is specified and segregated away from the pluripotent epiblast. At a later developmental stage, PrE forms motile parietal endoderm (PE) lying proximal to the trophectoderm, and visceral endoderm (VE) that contacts the developing epiblast and extraembryonic ectoderm. Mouse extraembryonic endoderm (XEN) cells were isolated and became widely used to study signals governing lineage specification. Rat XEN cell lines have also been derived, but were distinguished from mouse by expression of SSEA1 and Oct4. We showed here that rat XEN cells grown in the presence of a GSK3 inhibitor or overexpressing β-catenin exhibited enhanced formation of cell contacts and decreased motility. Rat XEN cells treated with BMP4 revealed similar morphological changes. Furthermore, we observed that rat XEN cells cultured with GSK3 inhibitor formed adhesion and tight junctions, and acquired bottom-top polarity, indicating the formation of VE cells. In contrast, forskolin, an activator of the cAMP pathway, induced the disruption of cell contacts in rat XEN cells. Treatment with forskolin induced PE formation and epithelial-mesenchymal transition (EMT) in rat XEN cells. Using microarray and real-time PCR assays, we found that VE versus PE formation of rat XEN cells was correlated with change in expression levels of VE or PE marker genes. Similar to forskolin, EMT was prompted upon treatment of rat XEN cells with recombinant parathyroid hormone related peptide (PTHRP), an activator of the cAMP pathway in vivo. Taken together, our data suggest that rat XEN cells are PrE-like cells. The activation of Wnt or BMP4 pathways in rat XEN cells leads to the acquisition of VE characteristics, whereas the activation of the PTHRP/cAMP pathway leads to EMT and the formation of PE.

CD146 expression in human breast cancer cell lines induces phenotypic and functional changes observed in Epithelial to Mesenchymal Transition

BACKGROUND

Metastasis is an important step in tumor progression leading to a disseminated and often incurable disease. First steps of metastasis include down-regulation of cell adhesion molecules, alteration of cell polarity and reorganization of cytoskeleton, modifications associated with enhanced migratory properties and resistance of tumor cells to anoikis. Such modifications resemble Epithelial to Mesenchymal Transition (EMT). In breast cancer CD146 expression is associated with poor prognosis and enhanced motility.

METHODOLOGY/PRINCIPAL FINDINGS

On 4 different human breast cancer cell lines, we modified CD146 expression either with shRNA technology in CD146 positive cells or with stable transfection of CD146 in negative cells. Modifications in morphology, growth and migration were evaluated. Using Q-RT-PCR, we analyzed the expression of different EMT markers. We demonstrate that high levels of CD146 are associated with loss of cell-cell contacts, expression of EMT markers, increased cell motility and increased resistance to doxorubicin or docetaxel. Experimental modulation of CD146 expression induces changes consistent with the above described characteristics: morphology, motility, growth in anchorage independent conditions and Slug mRNA variations are strictly correlated with CD146 expression. These changes are associated with modifications of ER (estrogen receptor) and Erb receptors and are enhanced by simultaneous and opposite modulation of JAM-A, or exposure to heregulin, an erb-B4 ligand.

CONCLUSIONS

CD146 expression is associated with an EMT phenotype. Several molecules are affected by CD146 expression: direct or indirect signaling contributes to EMT by increasing Slug expression. CD146 may also interact with Erb signaling by modifying cell surface expression of ErbB3 and ErbB4 and increased resistance to chemotherapy. Antagonistic effects of JAM-A, a tight junction-associated protein, on CD146 promigratory effects underline the complexity of the adhesion molecules network in tumor cell migration and metastasis.