Desmoglein 2 and desmocollin 2 depletions promote malignancy through distinct mechanisms in triple-negative and luminal breast cancer.

BACKGROUND: Aberrant expressions of desmoglein 2 (Dsg2) and desmocollin 2(Dsc2), the two most widely distributed desmosomal cadherins, have been found to play various roles in cancer in a context-dependent manner. Their specific roles on breast cancer (BC) and the potential mechanisms remain unclear. METHODS: The expressions of Dsg2 and Dsc2 in human BC tissues and cell lines were assessed by using bioinformatics analysis, immunohistochemistry and western blotting assays. Wound-healing and Transwell assays were performed to evaluate the cells' migration and invasion abilities. Plate colony-forming and MTT assays were used to examine the cells' capacity of proliferation. Mechanically, Dsg2 and Dsc2 knockdown-induced malignant behaviors were elucidated using western blotting assay as well as three inhibitors including MK2206 for AKT, PD98059 for ERK, and XAV-939 for ß-catenin. RESULTS: We found reduced expressions of Dsg2 and Dsc2 in human BC tissues and cell lines compared to normal counterparts. Furthermore, shRNA-mediated downregulation of Dsg2 and Dsc2 could significantly enhance cell proliferation, migration and invasion in triple-negative MDA-MB-231 and luminal MCF-7 BC cells. Mechanistically, EGFR activity was decreased but downstream AKT and ERK pathways were both activated maybe through other activated protein tyrosine kinases in shDsg2 and shDsc2 MDA-MB-231 cells since protein tyrosine kinases are key drivers of triple-negative BC survival. Additionally, AKT inhibitor treatment displayed much stronger capacity to abolish shDsg2 and shDsc2 induced progression compared to ERK inhibition, which was due to feedback activation of AKT pathway induced by ERK inhibition. In contrast, all of EGFR, AKT and ERK activities were attenuated, whereas ß-catenin was accumulated in shDsg2 and shDsc2 MCF-7 cells. These results indicate that EGFR-targeted therapy is not a good choice for BC patients with low Dsg2 or Dsc2 expression. Comparatively, AKT inhibitors may be more helpful to triple-negative BC patients with low Dsg2 or Dsc2 expression, while therapies targeting ß-catenin can be considered for luminal BC patients with low Dsg2 or Dsc2 expression. CONCLUSION: Our finding demonstrate that single knockdown of Dsg2 or Dsc2 could promote proliferation, motility and invasion in triple-negative MDA-MB-231 and luminal MCF-7 cells. Nevertheless, the underlying mechanisms were cellular context-specific and distinct.

The role of the desmosomal protein desmocollin 2 in tumour progression in triple negative breast cancer patients.

BACKGROUND: The disruption of epithelial features represents a critical step during breast cancer spread. In this context, the dysregulation of desmosomal proteins has been associated with malignant progression and metastasis formation. Curiously, both tumour suppressive and pro-metastatic roles have been attributed to desmosomal structures in different cancer entities. In the present study, we describe the pro-metastatic role of the desmosomal protein desmocollin 2 (DSC2) in breast cancer. METHODS: We analysed the prognostic role of DSC2 at mRNA and protein level using microarray data, western blot analysis and immunohistochemistry. Functional consequences of DSC2 overexpression and DSC2 knock down were investigated in the triple negative breast cancer (TNBC) cell line MDA-MB-231 and its brain-seeking subline MDA-MB-231-BR, respectively in vitro and in vivo. RESULTS: We found a significantly higher DSC2 expression in the more aggressive molecular subtypes HER2-positive and TNBC than in luminal breast cancers, as well as a significant correlation between increased DSC2 expression and a shorter disease-free-also in multivariate analysis-and overall survival. Additionally, a significant association between DSC2 expression in the primary tumour and an increased frequency of cerebral and lung metastasis could be observed. In vitro, ectopic DSC2 expression or DSC2 down-regulation in MDA-MB-231 and MDA-MB-231-BR led to a significant tumour cell aggregation increase and decrease, respectively. Furthermore, tumour cells displaying higher DSC2 levels showed increased chemoresistance in 3D structures, but not 2D monolayer structures, suggesting the importance of cell aggregation as a means for reduced drug diffusion. In an in vivo brain dissemination xenograft mouse model, reduced expression of DSC2 in the brain-seeking TNBC cells led to a decreased amount of circulating tumour cells/clusters and, in turn, to fewer and smaller brain metastatic lesions. CONCLUSION: We conclude that high DSC2 expression in primary TNBC is associated with a poorer prognosis, firstly by increasing tumour cell aggregation, secondly by reducing the diffusion and effectiveness of chemotherapeutic agents, and, lastly, by promoting the circulation and survival of tumour cell clusters, each of which facilitates distant organ colonisation.

Hemi- and Homozygous Loss-of-Function Mutations in DSG2 (Desmoglein-2) Cause Recessive Arrhythmogenic Cardiomyopathy with an Early Onset.

About 50% of patients with arrhythmogenic cardiomyopathy (ACM) carry a pathogenic or likely pathogenic mutation in the desmosomal genes. However, there is a significant number of patients without positive familial anamnesis. Therefore, the molecular reasons for ACM in these patients are frequently unknown and a genetic contribution might be underestimated. Here, we used a next-generation sequencing (NGS) approach and in addition single nucleotide polymor-phism (SNP) arrays for the genetic analysis of two independent index patients without familial medical history. Of note, this genetic strategy revealed a homozygous splice site mutation (DSG2-c.378+1G>T) in the first patient and a nonsense mutation (DSG2-p.L772X) in combination with a large deletion in DSG2 in the second one. In conclusion, a recessive inheritance pattern is likely for both cases, which might contribute to the hidden medical history in both families. This is the first report about these novel loss-of-function mutations in DSG2 that have not been previously identi-fied. Therefore, we suggest performing deep genetic analyses using NGS in combination with SNP arrays also for ACM index patients without obvious familial medical history. In the future, this finding might has relevance for the genetic counseling of similar cases.

A homozygous DSC2 deletion associated with arrhythmogenic cardiomyopathy is caused by uniparental isodisomy.

AIMS: We aimed to unravel the genetic, molecular and cellular pathomechanisms of DSC2 truncation variants leading to arrhythmogenic cardiomyopathy (ACM). METHODS AND RESULTS: We report a homozygous 4-bp DSC2 deletion variant c.1913_1916delAGAA, p.Q638LfsX647hom causing a frameshift carried by an ACM patient. Whole exome sequencing and comparative genomic hybridization analysis support a loss of heterozygosity in a large segment of chromosome 18 indicating segmental interstitial uniparental isodisomy (UPD). Ultrastructural analysis of the explanted myocardium from a mutation carrier using transmission electron microscopy revealed a partially widening of the intercalated disc. Using qRT-PCR we demonstrated that DSC2 mRNA expression was substantially decreased in the explanted myocardial tissue of the homozygous carrier compared to controls. Western blot analysis revealed absence of both full-length desmocollin-2 isoforms. Only a weak expression of the truncated form of desmocollin-2 was detectable. Immunohistochemistry showed that the truncated form of desmocollin-2 did not localize at the intercalated discs. In vitro, transfection experiments using induced pluripotent stem cell derived cardiomyocytes and HT-1080 cells demonstrated an obvious absence of the mutant truncated desmocollin-2 at the plasma membrane. Immunoprecipitation in combination with fluorescence measurements and Western blot analyses revealed an abnormal secretion of the truncated desmocollin-2. CONCLUSION: In summary, we unraveled segmental UPD as the likely genetic reason for a small homozygous DSC2 deletion. We conclude that a combination of nonsense mediated mRNA decay and extracellular secretion is involved in DSC2 related ACM.

Oxidized low-density lipoprotein attenuated desmoglein 1 and desmocollin 2 expression via LOX-1/Ca(2+)/PKC-ß signal in human umbilical vein endothelial cells.

Numerous studies have reported the presence of oxidized LDL (ox-LDL) and expression of its lectin-like receptor, LOX-1, have been shown in atherosclerotic regions. The present study aims to investigate the effects of ox-LDL on expression of desmoglein 1 (DSG1) and desmocollin 2 (DSC2) in endothelial cells, and to explore the role of LOX-1 mediated signal in the permeability injury associated with DSG1 and DSC2 disruption induced by oxidized lipoprotein. RT-PCR and Western blotting were applied to determine the mRNA and protein expression levels of DSG1 and DSC2 in human umbilical vein endothelial cells (HUVECs) respectively. Immunoreactivities of DSG1 and DSC2 were detected by laser scanning confocal microscope (LSCM). HUVEC monolayers permeability was evaluated by FITC-labeled LDL in transwell assay system. The possible signal was assessed using in vitro blocking LOX-1 or Ca(2+) channel or PKC. The DSG1 and DSC2 expression were decreased by ox-LDL in concentration- and time-dependent manner. The effects of ox-LDL were mediated by its endothelial receptor, LOX-1. In parallel experiments, ox-LDL increased the influx of extracellular calcium, activation of protein kinase C (PKC) and permeability to LDL, which was inhibited by the LOX-1blocking antibody (10 µg/ml), Ca(2+) channel blocker (Diltiazem, 50 µmol/L) and PKC-ß inhibitor (hispidin, 4 µmol/L). These results suggested that ox-LDL-induced decrease in DSG1 and DSC2 expression and monolayer barrier injury via calcium uptake and PKC-ß activation following up-regulation of LOX-1 is one of the mechanisms of inducing greater permeability in HUVECs.

Down-regulated desmocollin-2 promotes cell aggressiveness through redistributing adherens junctions and activating beta-catenin signalling in oesophageal squamous cell carcinoma.

In contrast to the well-recognized loss of adherens junctions in cancer progression, the role of desmosomal components in cancer development has not been well explored. We previously demonstrated that desmocollin-2 (DSC2), a desmosomal cadherin protein, is reduced in oesophageal squamous cell carcinoma (ESCC), and is associated with enhanced tumour metastasis and poor prognosis. Here, we report that restoration of DSC2 in ESCC cells impeded cell migration and invasion both in vitro and in vivo, whereas siRNA-mediated suppression of DSC2 expression increased cell motility. In E-cadherin-expressing ESCC cells, DSC2 restoration strengthened E-cadherin-mediated adherens junctions and promoted the localization of ß-catenin at these junctions, which indirectly inhibited ß-catenin-dependent transcription. These effects of DSC2 were not present in EC109 cells that lacked E-cadherin expression. ESCC patients with tumours that had reduced E-cadherin and negative DSC2 had poorer clinical outcomes than patients with tumours that lacked either E-cadherin or DSC2, implying that the invasive potential of ESCC cells was restricted by both DSC2 and E-cadherin-dependent junctions. Further studies revealed that DSC2 was a downstream target of miR-25. Enhanced miR-25 promoted ESCC cell invasiveness, whereas restoration of DSC2 abolished these effects. Collectively, our work suggests that miR-25-mediated down-regulation of DSC2 promotes ESCC cell aggressiveness through redistributing adherens junctions and activating beta-catenin signalling.

Validation the role of desmocollin-2 in osteosarcoma based on single cell and bulk RNA seq and experimental analyses.

Background: The aetiology of osteosarcoma (OS) remains unclear. Desmocollin-2 (DSC2) mediates intercellular adhesion and is involved in tumour progression. Therefore, we aim to investigate the potential role of DSC2 in OS. Methods: We analyzed the expression, prognostic value and immune infiltration of DSC2 in OS via single cell and bulk RNA seq data. Besides, the expression and function of DSC2 in OS were further verified by in vitro experiment. Results: We preliminarily determined that DSC2 was high expressed in OS, which was a risk factor for survival and had a strong relationship with immune cell infiltration. What's more, in vitro experiments also demonstrated that DSC2 was high expressed in OS cells, and silencing DSC2 would suppress proliferation, migration and invasion of OS cells. Conclusions: DSC2 may serve as an oncogene, which exerts a crucial role in tumor progression, predicting prognosis and immune cell infiltration in OS.

Cardiomyopathy related desmocollin-2 prodomain variants affect the intracellular cadherin transport and processing.

Background: Arrhythmogenic cardiomyopathy can be caused by genetic variants in desmosomal cadherins. Since cardiac desmosomal cadherins are crucial for cell-cell-adhesion, their correct localization at the plasma membrane is essential. Methods: Nine desmocollin-2 variants at five positions from various public genetic databases (p.D30N, p.V52A/I, p.G77V/D/S, p.V79G, p.I96V/T) and three additional conserved positions (p.C32, p.C57, p.F71) within the prodomain were investigated in vitro using confocal microscopy. Model variants (p.C32A/S, p.V52G/L, p.C57A/S, p.F71Y/A/S, p.V79A/I/L, p.I96l/A) were generated to investigate the impact of specific amino acids. Results: We revealed that all analyzed positions in the prodomain are critical for the intracellular transport. However, the variants p.D30N, p.V52A/I and p.I96V listed in genetic databases do not disturb the intracellular transport revealing that the loss of these canonical sequences may be compensated. Conclusion: As disease-related homozygous truncating desmocollin-2 variants lacking the transmembrane domain are not localized at the plasma membrane, we predict that some of the investigated prodomain variants may be relevant in the context of arrhythmogenic cardiomyopathy due to disturbed intracellular transport.

Efficient reprogramming of human fibroblasts using RNA reprogramming with DAPT and iDOT1L under normoxia conditions.

Introduction: Human induced pluripotent stem cells (hiPSCs) are generated through the reprogramming of somatic cells expressing a defined set of transcription factors. The advent of autologous iPSCs has enabled the generation of patient-specific iPSC lines and is expected to contribute to the exploration of cures and causes of diseases, drug screening, and tailor-made regenerative medicines. Efficient control of hiPSC derivation is beneficial for industrial applications. However, the mechanisms underlying somatic cell reprogramming remain unknown, while reprogramming efficiency remains extremely low, especially in human cells. Methods and results: We previously reported that chemical inhibition of the NOTCH signaling pathway and DOT1L promoted the generation of hiPSCs from keratinocytes, but the mechanisms and effect of this double inhibition on other types of cells remain to be investigated. Here, we found that the NOTCH/DOT1L inhibition markedly increased iPSC colony generation from human fibroblast cells via mRNA reprogramming, and mesenchymal to epithelial transition (MET)-related genes are significantly expressed in the early phase of the reprogramming. We successfully derived hiPSC lines using a single-cell sorting system under efficient reprogramming conditions. Conclusions: This user-friendly reprogramming approach paves the way for the development of hiPSC derivations in industrial applications of disease modeling and drug screening.

[Genetics of complex and syndromic palmoplantar keratoderma]. / Génétique des kératodermies palmoplantaires complexes et syndromiques.

Palmoplantar keratodermas (PPK) comprise a heterogenous group of acquired and hereditary disorders marked by excessive thickening of the epidermis of palms and soles. Hereditary PPKs can be classified into 3 groups: 1) isolated non-syndromic PPKs; 2) complex non-syndromic PPKs associated with other ectodermal defects; and 3) syndromic PPKs associated with extracutaneous manifestations. All types of inheritance have been observed: autosomal dominant, autosomal recessive, X-linked recessive, and mitochondrial. Some of these disorders are restricted to geographic isolates. This review describes the different genetic causes of hereditary syndromic and complex PPKs for which the genes have been identified. The identification of pathogenic variants has consequences in terms of genetic counseling, appropriate medical care and follow-up, especially for PPKs predisposing to hearing loss, cardiomyopathies, benign tumors or carcinomas. In addition, the development of targeted therapies based on pathophysiology of disorders should allow a more effective treatment of these conditions in the near future.

Regulating DSC2 Expression Affects the Proliferation and Apoptosis of Prostate Cancer Cells.

BACKGROUND: Prostate cancer threatens the life and health of men in China. Desmocollin-2 (DSC2) is a member of DSC family, abnormal expression of which can affect the invasion and metastasis of tumor cells. The aim of this study was to investigate the role of DSC2 in prostate cancer. MATERIALS AND METHODS: Regulating DSC2 expression in prostate cancer cells was conducted with transfection. The expression of DSC2, apoptosis-related proteins, cell cycle-related proteins and E-cadherin (E-cad)/ß-catenin pathway was detected by Western blot analysis. The proliferation, clone formation ability, migration, invasion and apoptosis of transfected cells were in turn detected by cell counting kit-8 (CCK-8) assay, clone formation assay, wound healing assay, transwell assay and flow cytometry analysis. RESULTS: DSC2 expression was increased in prostate cancer cells compared with RWPE-1 cells. Inhibition of DSC2 promoted the proliferation, clone formation ability, migration and invasion while suppressed apoptosis of LNCaP cells and PC-3 cells. Inhibition of DSC2 affected the expression of apoptosis-related proteins and cell cycle-related proteins according to the changes of apoptosis and proliferation. Furthermore, inhibition of DSC2 up-regulated the expression of p-ß-catenin and EGFR while down-regulated the expression of E-cad. DSC2 overexpression exerted the opposite effect of inhibition of DSC2 on LNCaP cells and PC-3 cells. CONCLUSION: DSC2 expression was increased in prostate cancer cells. In addition, inhibition of DSC2 promoted the proliferation, clone formation ability, migration and invasion while suppressed apoptosis of LNCaP cells and PC-3 cells, which provided the fundamental basis for treatment of prostate cancer.

G790del mutation in DSC2 alone is insufficient to develop the pathogenesis of ARVC in a mouse model.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart disease that causes heart failure and/or sudden cardiac death. Several desmosomal genes (DSC2, PKG, PKP2, DSP, and RyR2) are thought to be the causative gene involved in ARVC. Out of them, DSC2 mutations account for 2% of ARVC genetic abnormalities. This study aimed to clarify the effect of G790del mutation in DSC2 on the arrhythmogenic mechanism and cardiac function in a mouse model. RESULT: Neither the heterozygous +/G790del nor homozygous G790del/G790del mice showed structural and functional defects in the right ventricle (RV) or lethal arrhythmia. The homozygous G790del/G790del 6-month-old mice slightly showed left ventricular (LV) dysfunction. Cell shortening decreased with prolongation of intracellular Ca2+ transient in cardiomyocytes isolated from the homozygous G790del/G790del mice, and spontaneous Ca2+ transients were frequently observed in response to isoproterenol. CONCLUSIONS: G790del mutation in DSC2 was not relevant to the pathogenesis of ARVC, but showed a slight contractile dysfunction and Ca2+ dysregulation in the LV.

miR-92b-3p Functions As A Key Gene In Esophageal Squamous Cell Cancer As Determined By Co-Expression Analysis.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is a highly aggressive malignancy. The aims of the present study were to screen the critical miRNA and corresponding target genes that related to development of ESCC by weighted gene correlation network analysis (WGCNA) and investigate the functions by experimental validation. METHODS: Datasets of mRNA and miRNA expression data were downloaded from GEO. The R software was used for data preprocessing and differential expression gene analysis. The differentially expressed protein-coding genes (DEGs) and miRNAs (DEMs) were selected (FDR <0.05 or |Fold Change (FC)| >1.5). Meanwhile, 81 expression data of ESCC patients in TCGA combined with clinic information were applied by WGCNA to create networks. The correlational analyses between each module and clinical parameters were conducted, and enrichment analyses of GO and KEGG were subsequently performed. Then, a series of experiments were conducted in ESCC cells by use of miRNA mimics. RESULTS: In total, 4,023 DEGs and 328 DEMs were screened. After checking good genes and samples, 3,841 genes (3,696 DEGs and 145 DEMs) were used for WGCNA. As a consequence, altogether 11 gene modules were found. Among them, the brown modules were found to be strongly inversely associated with pathological grade. Meanwhile, has-mir-92b, the only miRNA in brown module, had a positive correlation with grade and negatively correlated with potential target gene (KFL4 and DCS2) in the same module. Furthermore, an increased expression of miR-92b-3p and down-regulated KLF4 and DSC2 protein was detected in the ESCC clinical samples. Up-regulated miR-92b-3p shortened G0/G1 phase and promote ESCC cells invasion and migration. Furthermore, we verified that DSC2 and KFL4 was target genes of miR-92b-3p by luciferase report assay. CONCLUSION: WGCNA is an efficient approach to system biology. By this procedure, miR-92b-3p was identified as an ESCC-promoting gene by target KLF4 and DCS2.

Epithelial adhesion molecules and the regulation of intestinal homeostasis during neutrophil transepithelial migration.

Epithelial adhesion molecules play essential roles in regulating cellular function and maintaining mucosal tissue homeostasis. Some form epithelial junctional complexes to provide structural support for epithelial monolayers and act as a selectively permeable barrier separating luminal contents from the surrounding tissue. Others serve as docking structures for invading viruses and bacteria, while also regulating the immune response. They can either obstruct or serve as footholds for the immune cells recruited to mucosal surfaces. Currently, it is well appreciated that adhesion molecules collectively serve as environmental cue sensors and trigger signaling events to regulate epithelial function through their association with the cell cytoskeleton and various intracellular adapter proteins. Immune cells, particularly neutrophils (PMN) during transepithelial migration (TEM), can modulate adhesion molecule expression, conformation, and distribution, significantly impacting epithelial function and tissue homeostasis. This review discusses the roles of key intestinal epithelial adhesion molecules in regulating PMN trafficking and outlines the potential consequences on epithelial function.