T-Cadherin is an auxiliary negative regulator of EGFR pathway activity in cutaneous squamous cell carcinoma: impact on cell motility

T-cadherin is a novel regulator of pericyte function during angiogenesis

Pericytes are mural cells that play an important role in regulation of angiogenesis and endothelial function. Cadherins are a superfamily of adhesion molecules mediating Ca²⁺-dependent homophilic cell-cell interactions that control morphogenesis and tissue remodeling. To date, classical N-cadherin is the only cadherin described on pericytes. Here, we demonstrate that pericytes also express T-cadherin (H-cadherin, CDH13), an atypical glycosyl-phosphatidylinositol (GPI)-anchored member of the superfamily that has previously been implicated in regulation of neurite guidance, endothelial angiogenic behavior, and smooth muscle cell differentiation and progression of cardiovascular disease. The aim of the study was to investigate T-cadherin function in pericytes. Expression of T-cadherin in pericytes from different tissues was performed by immunofluorescence analysis. Using lentivirus-mediated gain-of-function and loss-of-function in cultured human pericytes, we demonstrate that T-cadherin regulates pericyte proliferation, migration, invasion, and interactions with endothelial cells during angiogenesis in vitro and in vivo. T-cadherin effects are associated with the reorganization of the cytoskeleton, modulation of cyclin D1, α-smooth muscle actin (αSMA), integrin β3, metalloprotease MMP1, and collagen expression levels, and involve Akt/GSK3β and ROCK intracellular signaling pathways. We also report the development of a novel multiwell 3-D microchannel slide for easy analysis of sprouting angiogenesis from a bioengineered microvessel in vitro. In conclusion, our data identify T-cadherin as a novel regulator of pericyte function and support that it is required for pericyte proliferation and invasion during active phase of angiogenesis, while T-cadherin loss shifts pericytes toward the myofibroblast state rendering them unable to control endothelial angiogenic behavior.

High PD-L1 expression associates with low T-cadherin expression and poor prognosis in human papillomavirus-negative head and neck squamous cell carcinoma

BACKGROUND

This study aimed at exploring the correlation between T-cadherin and programmed death-ligand 1 (PD-L1), as well as their prognostic value in patients with human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC).

METHODS

Immunohistochemical staining was used to identify the protein expression of T-cadherin and PD-L1. Spearman linear correlation analysis was used to determine their association. Kaplan-Meier analysis was utilized to plot overall survival (OS) and disease-free survival (DFS) curves. Cox proportional hazards regression was used to conduct univariate and multivariate analysis.

RESULTS

The results showed a negative association between protein expression of T-cadherin and PD-L1 (r = -0.760, p < 0.001), positive expression of T-cadherin was associated with a better OS (p < 0.001) and DFS (p < 0.001), while positive PD-L1 expression was associated with a worse OS (p = 0.002) and DFS (p < 0.001). The expression of T-cadherin and PD-L1 were independent prognostic predictors for OS and DFS.

CONCLUSIONS

In conclusion, expression of T-cadherin and PD-L1 were largely inversely correlated and independent prognostic factors for patients with HPV-negative HNSCC.

Kinectin1 depletion promotes EGFR degradation via the ubiquitin-proteosome system in cutaneous squamous cell carcinoma

Depletion of kinectin1 (KTN1) provides a potential strategy for inhibiting tumorigenesis of cutaneous squamous cell carcinoma (cSCC) via reduction of epidermal growth factor receptor (EGFR) protein levels. Yet, the underlying mechanisms of KTN1 remain obscure. In this study, we demonstrate that KTN1 knockdown induces EGFR degradation in cSCC cells by promoting the ubiquitin-proteasome system, and that this effect is tumor cell-specific. KTN1 knockdown increases the expression of CCDC40, PSMA1, and ADRM1 to mediate tumor suppressor functions in vivo and in vitro. Mechanistically, c-Myc directly binds to the promoter region of CCDC40 to trigger the CCDC40-ADRM1-UCH37 axis and promote EGFR deubiquitination. Furthermore, KTN1 depletion accelerates EGFR degradation by strengthening the competitive interaction between PSMA1 and ADRM1 to inhibit KTN1/ADRM1 interaction at residues Met1-Ala252. These results are supported by studies in mouse xenografts and human patient samples. Collectively, our findings provide novel mechanistic insight into KTN1 regulation of EGFR degradation in cSCC.

Cadherin 13 Inhibits Pancreatic Cancer Progression and Epithelial-mesenchymal Transition by Wnt/β-Catenin Signaling

Cadherin 13 (CDH13) is an atypical cadherin that exerts tumor-suppressive effects on cancers derived from epithelial cells. Although the CDH13 promoter is frequently hypermethylated in pancreatic cancer (PC), the direct impact of CDH13 on PC is unknown. Accordingly, the expression of CDH13 in PC cell lines and paired PC tissues was examined by immunohistochemistry, quantitative real-time PCR and western blotting. Our findings showed that CDH13 was downregulated in PC tissues and cell lines. Moreover, cell proliferation, migration and invasion were detected by CCK-8 assay, transwell migration assay and transwell invasion assay, respectively. Xenograft tumor experiments were used to determine the biological function of CDH13 in vivo. As revealed by our data, CDH13 overexpression significantly inhibited the proliferation, migration and invasion of human PC cells in vitro. The inhibitory effect of CDH13 on PC was further confirmed in animal models. Mice subcutaneously or orthotopically transplanted with CDH13-overexpressing CFPAC-1 cells developed significantly smaller tumors with less liver metastases and mesenteric metastases than those of the control group. Next, transcriptomics and western blot analysis were used to identify the underlying mechanisms. Further molecular mechanism studies showed that CDH13 overexpression inhibited the activation of the Wnt/β-catenin signaling pathway and regulated the expression of epithelial-mesenchymal transition (EMT)-related markers. Our results indicated that CDH13 displayed an inhibitory effect on PC and suggested that CDH13 might be a potential biomarker and a new therapeutic target for PC.

Overexpression of T-cadherin inhibits the proliferation of oral squamous cell carcinoma through the PI3K/AKT/mTOR intracellular signalling pathway

OBJECTIVE

To evaluate T-cadherin gene expression in patients with oral squamous cell carcinoma(OSCC) and explore its effect on the proliferation of OSCC. Additionally, the present study aimed to determine whether the anti-proliferative effect of T-cadherin was associated with the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) signaling pathway.

DESIGN

A reverse transcription-quantitative polymerase chain reaction was performed to detect T-cadherin mRNA expression. A Cell Counting Kit-8 (CCK-8) assay was used to investigate the effect of T-cadherin on cellular proliferation. The survival curves were plotted by Kaplan-Meier method, and the differences between subgroups were determined by log-rank test. The protein expression of phosphorylated (p)-PI3K, total PI3K, p-AKT, total AKT, p-mTOR, total mTOR and cyclin D1was assessed using western blot.

RESULTS

It was revealed that the expression of T-cadherin mRNA was significantly decreased in OSCC samples compared with normal adjacent ones (P = 0.007), and that low T-cadherin expression was correlated with advanced clinical stage (P = 0.0249), higher pathological grade (P = 0.0288) and poor differentiation (P = 0.0295) of OSCC. In addition, T-cadherin negative expression was revealed to be associated with a worse progression‑free survival (PFS) in patients with OSCC. Furthermore, the overexpression of T-cadherin inhibited the proliferation of OSCC cell lines and suppressed the PI3K/AKT/mTOR signaling pathway. Importantly, the combined treatment of T-cadherin with the PI3K inhibitor LY294002 enhanced the inhibitory effect of T-cadherin on cellular proliferation and the PI3K/AKT/mTOR pathway.

CONCLUSIONS

The results of the present study suggested that T-cadherin may function as a tumor suppressor gene in OSCC through suppressing the PI3K/AKT/mTOR pathway, and that it may be a potential therapeutic target for OSCC.

Putative biomarkers for cervical cancer: SNVs, methylation and expression profiles

Cervical cancer is primarily caused by Human papillomavirus (HPV) infection, but other factors such as smoking habits, co-infections and genetic background, can also contribute to its development. Although this cancer is avoidable, it is the fourth most frequent type of cancer in females worldwide and can only be treated with chemotherapy and radical surgery. There is a need for biomarkers that will enable early diagnosis and targeted therapy for this type of cancer. Therefore, a systems biology pipeline was applied in order to identify potential biomarkers for cervical cancer, which show significant reports in three molecular aspects: DNA sequence variants, DNA methylation pattern and alterations in mRNA/protein expression levels. CDH1, CDKN2A, RB1 and TP53 genes were selected as putative biomarkers, being involved in metastasis, cell cycle regulation and tumour suppression. Other ten genes (CDH13, FHIT, PTEN, MLH1, TP73, CDKN1A, CACNA2D2, TERT, WIF1, APC) seemed to play a role in cervical cancer, but the lack of studies prevented their inclusion as possible biomarkers. Our results highlight the importance of these genes. However, further studies should be performed to elucidate the impact of DNA sequence variants and/or epigenetic deregulation and altered expression of these genes in cervical carcinogenesis and their potential as biomarkers for cervical cancer diagnosis and prognosis.

Cooperation of distinct Rac-dependent pathways to stabilise E-cadherin adhesion

The precise mechanisms via which Rac1 is activated by cadherin junctions are not fully known. In keratinocytes Rac1 activation by cadherin junctions requires EGFR signalling, but how EGFR does so is unclear. To address which activator could mediate E-cadherin signalling to Rac1, we investigated EGFR and two Rac1 GEFs, SOS1 and DOCK180. EGFR RNAi prevented junction-induced Rac1 activation and led to fragmented localization of E-cadherin at cadherin contacts. In contrast, depletion of another EGFR family member, ErbB3, did not interfere with either process. DOCK180 RNAi, but not SOS1, prevented E-cadherin-induced Rac1 activation. However, in a strong divergence from EGFR RNAi phenotype, DOCK180 depletion did not perturb actin recruitment or cadherin localisation at junctions. Rather, reduced DOCK180 levels impaired the resistance to mechanical stress of pre-formed cell aggregates. Thus, within the same cell type, EGFR and DOCK180 regulate Rac1 activation by newly-formed contacts, but control separate cellular events that cooperate to stabilise junctions.

Proteome profiling of keratinocytes transforming to malignancy

To shed light on the multistep process of squamous cell carcinoma development and the underlying pathologic mechanisms, we performed comparative proteome analysis of keratinocytes, keratinocytes stimulated with Il-1beta, and A431 epidermoid carcinoma cells. Fractionation of the cells into supernatant, nucleus, and cytoplasm was followed by protein separation, proteolytic digest, and nano-LC separation, and fragmentation using an ion trap mass spectrometer. Specific bioinformatics tools were used to generate a list of keratinocyte-specific proteins. Ninety percent of these proteins were found to be upregulated in keratinocytes versus the A431 cells. Classification of the identified proteins by biologic function and gene set enrichment analysis revealed that keratinocytes produced more proteins involved in cell differentiation, cell adhesion, cell junction, calcium ion, calmodulin binding, cytoskeleton organization, and cytokinesis, whereas A431 produced more proteins involved in cell cycle checkpoint, cell cycle process, RNA processing and transport, DNA damage and repair, RNA and DNA binding, and chromatin remodeling. The protein signatures of A431 and normal keratinocytes treated with IL-1beta showed marked similarity, confirming that inflammation is an important step in malignant transformation in nonmelanoma skin cancer. Thus, proteome profiling and bioinformatic processing may support the understanding of the underlying mechanisms, with the potential to facilitate development of early biomarkers and patient-tailored therapy.

EGFR and IGF-1R in regulation of prostate cancer cell phenotype and polarity: opposing functions and modulation by T-cadherin

T-cadherin is an atypical glycosylphosphatidylinsoitol-anchored member of the cadherin superfamily of adhesion molecules. We found that T-cadherin overexpression in malignant (DU145) and benign (BPH-1) prostatic epithelial cell lines or silencing in the BPH-1 cell line, respectively, promoted or inhibited migration and spheroid invasion in collagen I gel and Matrigel. T-cadherin-dependent effects were associated with changes in cell phenotype: overexpression caused cell dissemination and loss of polarity evaluated by relative positioning of the Golgi/nuclei in cell groups, whereas silencing caused formation of compact polarized epithelial-like clusters. Epidermal growth factor receptor (EGFR) and IGF factor-1 receptor (IGF-1R) were identified as mediators of T-cadherin effects. These receptors per se had opposing influences on cell phenotype. EGFR activation with EGF or IGF-1R inhibition with NVP-AEW541 promoted dissemination, invasion, and polarity loss. Conversely, inhibition of EGFR with gefitinib or activation of IGF-1R with IGF-1 rescued epithelial morphology and decreased invasion. T-cadherin silencing enhanced both EGFR and IGF-1R phosphorylation, yet converted cells to the morphology typical for activated IGF-1R. T-cadherin effects were sensitive to modulation of EGFR or IGF-1R activity, suggesting direct involvement of both receptors. We conclude that T-cadherin regulates prostate cancer cell behavior by tuning the balance in EGFR/IGF-1R activity and enhancing the impact of IGF-1R.

Quantitative proteomic analysis reveals effects of epidermal growth factor receptor (EGFR) on invasion-promoting proteins secreted by glioblastoma cells

Glioblastoma multiforme is a highly invasive and aggressive brain tumor with an invariably poor prognosis. The overexpression of epidermal growth factor receptor (EGFR) is a primary influencer of invasion and proliferation in tumor cells and the constitutively active EGFRvIII mutant, found in 30-65% of Glioblastoma multiforme, confers more aggressive invasion. To better understand how EGFR contributes to tumor aggressiveness, we investigated the effect of EGFR on the secreted levels of 65 rationally selected proteins involved in invasion. We employed selected reaction monitoring targeted mass spectrometry using stable isotope labeled internal peptide standards to quantity proteins in the secretome from five GBM (U87) isogenic cell lines in which EGFR, EGFRvIII, and/or PTEN were expressed. Our results show that cell lines with EGFR overexpression and constitutive EGFRvIII expression differ remarkably in the expression profiles for both secreted and intracellular signaling proteins, and alterations in EGFR signaling result in reproducible changes in concentrations of secreted proteins. Furthermore, the EGFRvIII-expressing mutant cell line secretes the majority of the selected invasion-promoting proteins at higher levels than other cell lines tested. Additionally, the intracellular and extracellular protein measurements indicate elevated oxidative stress in the EGFRvIII-expressing cell line. In conclusion, the results of our study demonstrate that EGFR signaling has a significant effect on the levels of secreted invasion-promoting proteins, likely contributing to the aggressiveness of Glioblastoma multiforme. Further characterization of these proteins may provide candidates for new therapeutic strategies and targets as well as biomarkers for this aggressive disease.

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.

Designing a multicellular organotypic 3D liver model with a detachable, nanoscale polymeric Space of Disse

The design of in vitro models that mimic the stratified multicellular hepatic microenvironment continues to be challenging. Although several in vitro hepatic cultures have been shown to exhibit liver functions, their physiological relevance is limited due to significant deviation from in vivo cellular composition. We report the assembly of a novel three-dimensional (3D) organotypic liver model incorporating three different cell types (hepatocytes, liver sinusoidal endothelial cells, and Kupffer cells) and a polymeric interface that mimics the Space of Disse. The nanoscale interface is detachable, optically transparent, derived from self-assembled polyelectrolyte multilayers, and exhibits a Young's modulus similar to in vivo values for liver tissue. Only the 3D liver models simultaneously maintain hepatic phenotype and elicit proliferation, while achieving cellular ratios found in vivo. The nanoscale detachable polymeric interfaces can be modulated to mimic basement membranes that exhibit a wide range of physical properties. This facile approach offers a versatile new avenue in the assembly of engineered tissues. These results demonstrate the ability of the tri-cellular 3D cultures to serve as an organotypic hepatic model that elicits proliferation and maintenance of phenotype and in vivo-like cellular ratios.

Role of adiponectin and its receptors in cancer

Adiponectin (APN), a novel hormone/cytokine derived from adipocyte tissue, is involved in various physiological functions. Genetics, nutrition, and adiposity are factors contributing to circulating plasma concentrations of APN. Clinical correlation studies have shown that lower levels of serum APN are associated with increased malignancy of various cancers, such as breast and colon cancers, suggesting that APN has a role in tumorigenesis. APN affects insulin resistance, thus further influencing cancer development. Tumor cells may express receptors for APN. Cellular signaling is the mechanism by which APN exerts its host-protective responses. These factors suggest that serum APN levels and downstream signaling targets of APN may serve as potential diagnostic markers for malignancies. Further research is necessary to clarify the exact role of APN in cancer diagnosis and therapy.

T-cadherin loss promotes experimental metastasis of squamous cell carcinoma

T-cadherin is gaining recognition as a determinant for the development of incipient invasive squamous cell carcinoma (SCC). However, effects of T-cadherin expression on the metastatic potential of SCC have not been studied. Here, using a murine model of experimental metastasis following tail vein injection of A431 SCC cells we report that loss of T-cadherin increased both the incidence and rate of appearance of lung metastases. T-cadherin-silenced SCC metastases were highly disordered with evidence of single cell dissemination away from main foci whereas SCC metastases overexpressing T-cadherin developed as compact, tightly organised sheets. SCC cell adhesion to vascular endothelial cells (EC) in culture was increased for T-cadherin-silenced SCC and decreased for T-cadherin-overexpressing SCC. Confocal microscopy showed that T-cadherin-silenced SCC adherent on EC display an elongated morphology with long thin extensions and a high degree of intercalation within the EC monolayer, whereas SCC overexpressing T-cadherin formed poorly-spread multicellular aggregates that remain on the outer surface of the EC monolayer. T-cadherin-deficient SCC or human keratinocyte cells exhibited increased transendothelial migration in vitro which could be attenuated in the presence of EGFR inhibitor gefitinib. Our data suggest that loss of T-cadherin can increase metastatic potential and aggressiveness of SCC, possibly due to facilitating arrest and extravasation through the vascular wall and/or more efficient establishment of metastases in the new microenvironment.