Context-specific effects of fibulin-5 (DANCE/EVEC) on cell proliferation, motility, and invasion. Fibulin-5 is induced by transforming growth factor-beta and affects protein kinase cascades

The matricellular protein Fibulin-5 regulates β-cell proliferation in an autocrine/paracrine manner

The matricellular protein Fibulin-5 (Fbln5) is a secreted protein that is essential for elastic fiber formation, and pancreatic islets are usually surrounded by the extracellular matrix (ECM), which includes elastic fibers. However, much uncertainty remains regarding the function of the ECM and its components in β-cells. Here, we describe the role of Fbln5 in β-cell replication. Fbln5 expression was increased upon glucose stimulation in β-cells of mouse and human islets. β-Cell-specific Fbln5-knockout (βFbln5KO) mice exhibit significantly reduced β-cell proliferation in vivo but not in vitro. Secreted extracellular Fbln5 enhances β-cell replication. Fbln5-deficient β-cells exhibit the downregulated expression of the gene encoding Polo-like kinase 1 (PLK1), which is accompanied by ERK-mediated FoxM1 nuclear export. These data suggest that Fbln5 is secreted from β-cells in response to glucose and plays important roles in the appropriate maintenance of β-cell functions in an autocrine or paracrine manner.

Proteogenomic Characterization of Early Intrahepatic Recurrence after Curative-Intent Treatment of Colorectal Liver Metastases

Clinical and pathological factors are insufficient to accurately identify patients at risk of early recurrence after curative-intent treatment of colorectal liver metastases (CRLM). This study aimed to identify candidate prognostic proteogenomic biomarkers for early intrahepatic recurrence after curative-intent resection of CRLM. Patients diagnosed with intrahepatic recurrence within 6 months of liver resection were categorized as the "early recurrence" group, while those who achieved a recurrence-free status for 10 years were designated as "durable remission". Comprehensive genomic and proteomic profiling of fresh frozen samples from these prognostically distinct groups was performed using the TruSight Oncology 500 assay and label-free data-dependent acquisition liquid chromatography-mass spectrometry. Genetic alterations were identified in 117 of the 523 profiled genes in patients with early recurrence. The most common somatic mutations linked to early recurrence were TP53 (88%), APC (71%), KRAS (38%), and SMAD4 (21%). SMAD4 alterations were absent in samples from patients with a durable remission. Calponin-2, versican core protein, glutathione peroxidase 3, fibulin-5, and amyloid-β precursor protein were upregulated more than 2-fold in early recurrence. Exploratory analysis of these proteogenomic biomarkers suggests that SMAD4, calponin-2, and glutathione peroxidase 3 may have the potential to predict early recurrence, enabling improved prognostication and precision oncology in CRLM.

Homeostatic Regulation of Pro-Angiogenic and Anti-Angiogenic Proteins via Hedgehog, Notch Grid, and Ephrin Signaling in Tibial Dyschondroplasia

Precise coupling of two fundamental mechanisms, chondrogenesis and osteogenesis via angiogenesis, plays a crucial role during rapid proliferation of growth plates, and alteration in their balance might lead to pathogenic conditions. Tibial dyschondroplasia (TD) is characterized by an avascular, non-mineralized, jade-white "cartilaginous wedge" with impaired endochondral ossification and chondrocyte proliferation at the proximal end of a tibial bone in rapidly growing poultry birds. Developing vascular structures are dynamic with cartilage growth and are regulated through homeostatic balance among pro and anti-angiogenic proteins and cytokines. Pro-angiogenic factors involves a wide spectrum of multifactorial mitogens, such as vascular endothelial growth factors (VEGF), platelet-derived growth factors (PDGF), basic fibroblast growth factor (bFGF), placental growth factors, transforming growth factor-β (TGF-β), and TNF-α. Considering their regulatory role via the sonic hedgehog, notch-gridlock, and ephrin-B2/EphB4 pathways and inhibition through anti-angiogenic proteins like angiostatin, endostatin, decoy receptors, vasoinhibin, thrombospondin, PEX, and troponin, their possible role in persisting inflammatory conditions like TD was studied in the current literature review. Balanced apoptosis and angiogenesis are vital for physiological bone growth. Any homeostatic imbalance among apoptotic, angiogenetic, pro-angiogenic, or anti-angiogenic proteins ultimately leads to pathological bone conditions like TD and osteoarthritis. The current review might substantiate solid grounds for developing innovative therapeutics for diseases governed by the disproportion of angiogenesis and anti-angiogenesis proteins.

Loss of NDUFS1 promotes gastric cancer progression by activating the mitochondrial ROS-HIF1α-FBLN5 signaling pathway

BACKGROUND

Recent studies suggested that NDUFS1 has an important role in human cancers; however, the effects of NDUFS1 on gastric cancer (GC) are still not fully understood.

METHODS

We confirmed that NDUFS1 is downregulated in GC cells through western blot immunohistochemistry and bioinformation analysis. The effect of NDUFS1 on GC was studied by CCK-8, colony formation, transwell assay in vitro and Mouse xenograft assay in vivo. Expression and subcellular localization of NDUFS1 and the content of mitochondrial reactive oxygen species (mROS) was observed by confocal reflectance microscopy.

RESULTS

Reduced expression of NDUFS1 was found in GC tissues and cell lines. Also, NDUFS1 overexpression inhibited GC cell proliferation, migration, and invasion in vitro as well as growth and metastasis in vivo. Mechanistically, NDUFS1 reduction led to the activation of the mROS-hypoxia-inducible factor 1α (HIF1α) signaling pathway. We further clarified that NDUFS1 reduction upregulated the expression of fibulin 5 (FBLN5), a transcriptional target of HIF1α, through activation of mROS-HIF1α signaling in GC cells.

CONCLUSIONS

The results of this study indicate that NDUFS1 downregulation promotes GC progression by activating an mROS-HIF1α-FBLN5 signaling pathway.

Clinical and Biological Significances of FBLN5 in Gastric Cancer

Abnormal FBLN5 expression levels are related to various cancer types. This study is the first to explore its clinical and biological significances in gastric cancer (GC). We used The Cancer Genome Atlas-GC (TCGA-GC) and Gene Expression Omnibus (GEO) databases to identify the differential expression of FBLN5, and its association with clinical pathological characteristics was analyzed. A Kaplan-Meier plotter was used to calculate the impact of FBLN5 on GC patient prognosis, and the biological functions of FBLN5 were analyzed. In addition, we constructed a GC tissue microarray, and performed an immunohistochemical staining of FBLN5 to verify our findings. Western blotting was conducted simultaneously to confirm that FBLN5 was overexpressed in GC. We found that the high level of FBLN5 mRNA in GC was associated with a poor prognosis. High FBLN5 expression levels were significantly correlated with INFc and N3 lymph node metastasis. Univariate and multivariate analyses showed that FBLN5 expression levels and lymph node metastasis rate were independent risk factors related to GC patient prognosis, which can be combined to construct a nomogram to serve patients. Therefore, we believe that FBLN5 is significantly related to the poor prognosis of GC patients. FBLN5 is a valuable prognostic indicator to evaluate the prognosis of GC.

Elastic Fibre Proteins in Elastogenesis and Wound Healing

As essential components of our connective tissues, elastic fibres give tissues such as major blood vessels, skin and the lungs their elasticity. Their formation is complex and co-ordinately regulated by multiple factors. In this review, we describe key players in elastogenesis: fibrillin-1, tropoelastin, latent TGFβ binding protein-4, and fibulin-4 and -5. We summarise their roles in elastogenesis, discuss the effect of their mutations on relevant diseases, and describe their interactions involved in forming the elastic fibre network. Moreover, we look into their roles in wound repair for a better understanding of their potential application in tissue regeneration.

EGFR-Dependent Extracellular Matrix Protein Interactions Might Light a Candle in Cell Behavior of Non-Small Cell Lung Cancer

Lung cancer remains the leading cause of cancer-related death and is associated with a poor prognosis. Lung cancer is divided into 2 main types: the major in incidence is non-small cell lung cancer (NSCLC) and the minor is small cell lung cancer (SCLC). Although NSCLC progression depends on driver mutations, it is also affected by the extracellular matrix (ECM) interactions that activate their corresponding signaling molecules in concert with integrins and matrix metalloproteinases (MMPs). These signaling molecules include cytoplasmic kinases, small GTPases, adapter proteins, and receptor tyrosine kinases (RTKs), particularly the epidermal growth factor receptor (EGFR). In NSCLC, the interplay between ECM and EGFR regulates ECM stiffness, angiogenesis, survival, adhesion, migration, and metastasis. Furthermore, some tumor-promoting ECM components (e.g., glycoproteins and proteoglycans) enhance activation of EGFR and loss of PTEN. On the other hand, other tumor-suppressing glycoproteins and -proteoglycans can inhibit EGFR activation, suppressing cell invasion and migration. Therefore, deciphering the molecular mechanisms underlying EGFR and ECM interactions might provide a better understanding of disease pathobiology and aid in developing therapeutic strategies. This review critically discusses the crosstalk between EGFR and ECM affecting cell behavior of NSCLC, as well as the involvement of ECM components in developing resistance to EGFR inhibition.

Alveologenesis: What Governs Secondary Septa Formation

The simplification of alveoli leads to various lung pathologies such as bronchopulmonary dysplasia and emphysema. Deep insight into the process of emergence of the secondary septa during development and regeneration after pneumonectomy, and into the contribution of the drivers of alveologenesis and neo-alveolarization is required in an efficient search for therapeutic approaches. In this review, we describe the formation of the gas exchange units of the lung as a multifactorial process, which includes changes in the actomyosin cytoskeleton of alveocytes and myofibroblasts, elastogenesis, retinoic acid signaling, and the contribution of alveolar mesenchymal cells in secondary septation. Knowledge of the mechanistic context of alveologenesis remains incomplete. The characterization of the mechanisms that govern the emergence and depletion of αSMA will allow for an understanding of how the niche of fibroblasts is changing. Taking into account the intense studies that have been performed on the pool of lung mesenchymal cells, we present data on the typing of interstitial fibroblasts and their role in the formation and maintenance of alveoli. On the whole, when identifying cell subpopulations in lung mesenchyme, one has to consider the developmental context, the changing cellular functions, and the lability of gene signatures.

Effect of fibulin-5 on aldosterone-induced apoptosis in human ascending aortic smooth muscle cells

The aim of the current study was to investigate the effect of aldosterone on apoptosis in human aortic smooth muscle cells (HA-VSMC) and to determine the role of fibulin-5 in the aldosterone-induced apoptosis of HA-VSMC cells. Through the construction of a fibulin-5 eukaryotic overexpression vector and a short hairpin RNA interference plasmid, fibulin-5 was overexpressed and silenced, respectively. The role of fibulin-5 in the aldosterone-induced apoptosis of HA-VSMC was subsequently determined. The overexpression of fibulin-5 inhibited the apoptosis of cells, particularly at low concentrations of aldosterone; a smaller effect on apoptosis was induced by high concentrations of aldosterone. fibulin-5 knockdown promoted the apoptosis of cells induced by high concentrations of aldosterone but had a smaller effect on the apoptosis of cells induced by low concentrations of aldosterone. Therefore, the results of the current study indicate that fibulin-5 inhibits the aldosterone-induced apoptosis of HA-VSMC cells and that this effect may be altered by changing the aldosterone concentration.

Role of Fibulins in Embryonic Stage Development and Their Involvement in Various Diseases

The extracellular matrix (ECM) plays an important role in the evolution of early metazoans, as it provides structural and biochemical support to the surrounding cells through the cell–cell and cell–matrix interactions. In multi-cellular organisms, ECM plays a pivotal role in the differentiation of tissues and in the development of organs. Fibulins are ECM glycoproteins, found in a variety of tissues associated with basement membranes, elastic fibers, proteoglycan aggregates, and fibronectin microfibrils. The expression profile of fibulins reveals their role in various developmental processes such as elastogenesis, development of organs during the embryonic stage, tissue remodeling, maintenance of the structural integrity of basement membrane, and elastic fibers, as well as other cellular processes. Apart from this, fibulins are also involved in the progression of human diseases such as cancer, cardiac diseases, congenital disorders, and chronic fibrotic disorders. Different isoforms of fibulins show a dual role of tumor-suppressive and tumor-promoting activities, depending on the cell type and cellular microenvironment in the body. Knockout animal models have provided deep insight into their role in development and diseases. The present review covers details of the structural and expression patterns, along with the role of fibulins in embryonic development and disease progression, with more emphasis on their involvement in the modulation of cancer diseases.

Overexpression of fibulin-3 in tumor tissue predicts poor survival of malignant mesothelioma patients from hand-spinning asbestos exposed area in eastern China

Fibulin-3 is an extracellular matrix glycoprotein widely expressed in various tissues. Tissue fibulin-3 expression have never been reported in association with prognosis of mesothelioma. Hence, we sought to determine the association between fibulin-3 expression and mesothelioma survival. We made a tissue microarray, which was comprised of cancer and normal tissue from mesothelioma patients (n = 82) during the period 1998-2017 in China. Fibulin-3 and HGMB1 expression were analyzed by immunohistochemistry method. Kaplan-Meier method and Cox proportional hazard models were used for analyzing survival data. Overall, 61 cases (74.4%) were female; 90.2% were of epithelioid type; the median overall survival time was 12.5 months. Fibulin-3 and HMGB1 were highly expressed in tumor tissue rather than adjacent tissue. The expression of fibulin-3 in tissue was correlated with that of HMGB1 (r = 0.32, P = 0.003). High expression of fibulin-3 in tumor tissue could predict poor survival in patients with mesothelioma (P = 0.02). This remained true in a multivariate model, with a significant hazard ratio of 1.91. We demonstrated that fibulin-3 in tumor tissue was a novel biomarker of poor survival of mesothelioma, suggesting it may be a relevant target for therapeutic intervention.

Fibulin 5, a human Wharton's jelly-derived mesenchymal stem cells-secreted paracrine factor, attenuates peripheral nervous system myelination defects through the Integrin-RAC1 signaling axis

In the peripheral nervous system (PNS), proper development of Schwann cells (SCs) contributing to axonal myelination is critical for neuronal function. Impairments of SCs or neuronal axons give rise to several myelin-related disorders, including dysmyelinating and demyelinating diseases. Pathological mechanisms, however, have been understood at the elementary level and targeted therapeutics has remained undeveloped. Here, we identify Fibulin 5 (FBLN5), an extracellular matrix (ECM) protein, as a key paracrine factor of human Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) to control the development of SCs. We show that co-culture with WJ-MSCs or treatment of recombinant FBLN5 promotes the proliferation of SCs through ERK activation, whereas FBLN5-depleted WJ-MSCs do not. We further reveal that during myelination of SCs, FBLN5 binds to Integrin and modulates actin remodeling, such as the formation of lamellipodia and filopodia, through RAC1 activity. Finally, we show that FBLN5 effectively restores the myelination defects of SCs in the zebrafish model of Charcot-Marie-Tooth (CMT) type 1, a representative demyelinating disease. Overall, our data propose human WJ-MSCs or FBLN5 protein as a potential treatment for myelin-related diseases, including CMT.

FBLN5 is targeted by microRNA‑27a‑3p and suppresses tumorigenesis and progression in high‑grade serous ovarian carcinoma

High-grade serous ovarian carcinoma (HGSOC) is one of the most lethal gynecological malignancies; however, the precise molecular mechanisms have not been fully characterized. Fibulin-5 (FBLN-5) is an extracellular matrix (ECM) glycoprotein, and plays a crucial role in maintaining the stability of ECM structures, regulating cell proliferation and tumorigenesis. In the present study, the expression of FBLN-5, as determined by western blot analysis and immunohistochemistry, was significantly increased in normal fallopian tube (FT) samples compared with that in HGSOC samples, and decreased FBLN5 expression was associated with unfavorable prognosis of HGSOC. Functional characterization revealed that FBLN5 overexpression significantly inhibited migration, invasion and proliferation abilities of ovarian cancer cells in vitro. Furthermore, micro (mi)RNA-27a-3p (miR-27a-3p) was revealed to be increased in HGSOC, and dual-luciferase reporter assay indicated that miR-27a-3p was functioned as a negative regulator of FBLN5 by directly binding with its 3′-untranslated region. Collectively, FBLN5 expression was associated with prognosis, proliferation, and metastasis in HGSOC. We hypothesized that FBLN5 was targeted by miR-27a-3p and may serve as a biomarker and provide a new therapeutic approach for the treatment of HGSOC.

Nutricosmetics: A brief overview

The nutricosmetics are products and ingredients that act as nutritional supplements to care skin, nails, and hair natural beauty. They work from the inside to promote beauty from within. Nutricosmetic is the latest trend in the beauty industry. This tendency rapidly gained many followers because it fits with the modern culture: Today, consumers are very careful with the food that they introduce into their body, and there is also an increasing demand for natural products able to enhance one's health and beauty without side effects and significant traction before use. However, many nutricosmetic products are considered effective due to the historical use and word of mouth. Comprehensive analysis of the global nutricosmetics market is conducted considering form, end-user applications, and some product components such as collagen, peptides, proteins, vitamins, carotenes, minerals, and omega-3 fatty acid are reported. Plant extract ingredients used in nutricosmetic are also described.

Fibulin-7 is overexpressed in glioblastomas and modulates glioblastoma neovascularization through interaction with angiopoietin-1

Glioblastoma (GBM) is pathologically characterized by highly malignant neoplastic cells, focal necrosis and aberrant blood vessels composed of disorganized endothelial cells and pericytes. The recent cancer microarray database revealed upregulation of fibulin-7 (Fbln7), a member of the fibulin family, but provided no information on the tissue localization or biological function. In the present study, we demonstrated that Fbln7 is markedly overexpressed by the GBM tissue among astrocytic tumors, and immunolocalized mainly to endothelial cells and pericytes of the glomeruloid and hypertrophied microvessels. The production of Fbln7 by endothelial cells and pericytes was confirmed in cultured human umbilical vein endothelial cells (HUVEC) and human brain vascular pericytes (HBVP) and vascular endothelial growth factor (VEGF) stimulated the Fbln7 expression in HUVEC. Fbln7 bound to angiopoietin-1, but not angiopoietin-2 or Tie2 receptor, through interaction between the N-terminal portions of Fbln7 and angiopoietin-1, and it blocked phosphorylation of Tie2 receptor in HUVEC. In a coculture assay using HUVEC and HBVP, multilayered and irregular-shaped tube-like structures of HUVEC were induced by treatment with a high concentration of VEGF. This was accompanied by Fbln7 overproduction by HUVEC and angiopoietin-1 expression by HBVP. The production of aberrant VEGF-induced tube-like structures was attenuated by treatment with antibody or synthetic peptides specific to the Fbln7 N-terminal domain or knockdown of Fbln7. These data demonstrate that Fbln7 is overexpressed by endothelial cells and pericytes of the abnormal microvessels in GBM, and suggest that Fbln7 may contribute to the aberrant vessel formation by modulation of the angiopoietin-1/angiopoietin-2-Tie2 axis.

Extracellular Interactions between Fibulins and Transforming Growth Factor (TGF)-β in Physiological and Pathological Conditions

Transforming growth factor (TGF)-β is a multifunctional peptide growth factor that has a vital role in the regulation of cell growth, differentiation, inflammation, and repair in a variety of tissues, and its dysregulation mediates a number of pathological conditions including fibrotic disorders, chronic inflammation, cardiovascular diseases, and cancer progression. Regulation of TGF-β signaling is multifold, but one critical site of regulation is via interaction with certain extracellular matrix (ECM) microenvironments, as TGF-β is primarily secreted as a biologically inactive form sequestrated into ECM. Several ECM proteins are known to modulate TGF-β signaling via cell–matrix interactions, including thrombospondins, SPARC (Secreted Protein Acidic and Rich in Cystein), tenascins, osteopontin, periostin, and fibulins. Fibulin family members consist of eight ECM glycoproteins characterized by a tandem array of calcium-binding epidermal growth factor-like modules and a common C-terminal domain. Fibulins not only participate in structural integrity of basement membrane and elastic fibers, but also serve as mediators for cellular processes and tissue remodeling as they are highly upregulated during embryonic development and certain disease processes, especially at the sites of epithelial–mesenchymal transition (EMT). Emerging studies have indicated a close relationship between fibulins and TGF-β signaling, but each fibulin plays a different role in a context-dependent manner. In this review, regulatory interactions between fibulins and TGF-β signaling are discussed. Understanding biological roles of fibulins in TGF-β regulation may introduce new insights into the pathogenesis of some human diseases.

RNA-Seq reveals differentially expressed genes affecting polyunsaturated fatty acids percentage in the Huangshan Black chicken population

Fatty acids metabolic products determine meat quality in chickens. Identifying genes associated with fatty acids composition could provide valuable information for the complex genetic networks of genes with underlying variations in fatty acids synthesis. RNA sequencing (RNA-Seq) was conducted to explore the chicken transcriptome from the thigh muscle tissue of 6 Huangshan Black Chickens with 3 extremely high and low phenotypic values for percentage of polyunsaturated fatty acids (PUFAs). In total, we obtained 41,139,108–44,901,729 uniquely mapped reads, which covered 74.15% of the current annotated transcripts including 18964 mRNA transcripts, across all the six thigh muscle tissue samples. Of these, we revealed 274 differentially expressed genes (DEGs) with a highly significant correlation with polyunsaturated fatty acids percentage between the comparison groups based on the ratio of PUFA/SFA. Gene ontology and pathway analysis indicated that the DEGs were enriched in particular biological processes affecting fatty acids metabolism, biosynthesis of unsaturated fatty acids (USFAs), and cell junction-related pathways. Integrated interpretation of differential gene expression and formerly reported quantitative trait loci (QTL) demonstrated that FADS2, DCN, FRZB, OGN, PRKAG3, LHFP, CHCHD10, CYTL1, FBLN5, and ADGRD1 are the most promising candidate genes affecting polyunsaturated fatty acids percentage.

Dysregulation of fibulin-5 and matrix metalloproteases in epithelial ovarian cancer

Fibulin 5 (FBLN5) is an extracellular matrix glycoprotein that suppresses matrix metalloprotease 9 (MMP-9), angiogenesis and epithelial cell motility. Here, we investigated the regulation and function of FBLN5 in epithelial ovarian cancer (EOC). FBLN5 mRNA was down-regulated 5-fold in EOC relative to benign ovary. Not surprisingly, MMP9 mRNA and enzyme activity were increased significantly, and inversely correlated with FBLN5 gene expression. FBLN5 degradation products of 52.8 and 41.3 kDa were increased substantially in EOC. We identified two candidate proteases (serine elastase and MMP-7, but not MMP-9) that cleave FBLN5. MMP-7, but not neutrophil elastase, gene expression was increased dramatically in EOC. Recombinant FBLN5 significantly inhibited adhesion of EOC cells to both laminin and collagen I. Finally, using immunohistochemistry, we found immunoreactive FBLN5 within tumor macrophages throughout human EOC tumors. This work indicates that FBLN5 is degraded in EOC most likely by proteases enriched in macrophages of the tumor microenvironment. Proteolysis of FBLN5 serves as a mechanism to promote cell adhesion and local metastasis of ovarian cancer cells. Promotion of a stable ECM with intact FBLN5 in the tumor matrix may serve as a novel therapeutic adjunct to prevent spread of ovarian cancer.

EFEMP1 is repressed by estrogen and inhibits the epithelial-mesenchymal transition via Wnt/β-catenin signaling in endometrial carcinoma

Epidermal growth factor-containing fibulin-like extracellular matrix protein 1 (EFEMP1) acted as a tumor suppressor in endometrial carcinoma (EC). However, the correlation between EFEMP1 and estrogen is unknown. Here, we reported that the expression of EFEMP1 was conversely associated with ERα in endometrial carcinoma tissues. In endometrial carcinoma cells, estrogen/ERα signaling significantly suppressed the expression of EFEMP1. Moreover, chromatin immunoprecipitation (CHIP) and dual-luciferase reporter assays demonstrate that estrogen/ERα bound to the estrogen response element (ERE) located in EFEMP1 promoter and repressed its expression. Besides, in vitro and in vivo, EFEMP1 could remarkably suppress the expression of epithelial-mesenchymal transition (EMT) markers such as Vimentin, Snail and the Wnt/β-catenin target genes like Cyclin-D1 and c-Myc, which could be restored when EFEMP1 was silenced. In addition, XAV93920 (the inhibitor of the Wnt/β-catenin pathway) blocked and LiCl (the activator of the Wnt/β-catenin pathway) enhanced the effect of EFEMP1 on EMT. In conclusion, we demonstrated that estrogen/ERα signal suppresses EFEMP1. Besides, EFEMP1 inhibits EMT via interfering the Wnt/β-catenin signaling.

Comprehensive transcriptome analysis of fluid shear stress altered gene expression in renal epithelial cells

Renal epithelial cells are exposed to mechanical forces due to flow‐induced shear stress within the nephrons. Shear stress is altered in renal diseases caused by tubular dilation, obstruction, and hyperfiltration, which occur to compensate for lost nephrons. Fundamental in regulation of shear stress are primary cilia and other mechano‐sensors, and defects in cilia formation and function have profound effects on development and physiology of kidneys and other organs. We applied RNA sequencing to get a comprehensive overview of fluid‐shear regulated genes and pathways in renal epithelial cells. Functional enrichment‐analysis revealed TGF‐β, MAPK, and Wnt signaling as core signaling pathways up‐regulated by shear. Inhibitors of TGF‐β and MAPK/ERK signaling modulate a wide range of mechanosensitive genes, identifying these pathways as master regulators of shear‐induced gene expression. However, the main down‐regulated pathway, that is, JAK/STAT, is independent of TGF‐β and MAPK/ERK. Other up‐regulated cytokine pathways include FGF, HB‐EGF, PDGF, and CXC. Cellular responses to shear are modified at several levels, indicated by altered expression of genes involved in cell‐matrix, cytoskeleton, and glycocalyx remodeling, as well as glycolysis and cholesterol metabolism. Cilia ablation abolished shear induced expression of a subset of genes, but genes involved in TGF‐β, MAPK, and Wnt signaling were hardly affected, suggesting that other mechano‐sensors play a prominent role in the shear stress response of renal epithelial cells. Modulations in signaling due to variations in fluid shear stress are relevant for renal physiology and pathology, as suggested by elevated gene expression at pathological levels of shear stress compared to physiological shear.

Identification of the matricellular protein Fibulin-5 as a target molecule of glucokinase-mediated calcineurin/NFAT signaling in pancreatic islets

Glucokinase-mediated glucose signaling induces insulin secretion, proliferation, and apoptosis in pancreatic β-cells. However, the precise molecular mechanisms underlying these processes are not clearly understood. Here, we demonstrated that glucokinase activation using a glucokinase activator (GKA) significantly upregulated the expression of Fibulin-5 (Fbln5), a matricellular protein involved in matrix-cell signaling, in isolated mouse islets. The islet Fbln5 expression was induced by ambient glucose in a time- and dose-dependent manner and further enhanced by high-fat diet or the deletion of insulin receptor substrate 2 (IRS-2), whereas the GKA-induced increase in Fbln5 expression was diminished in Irs-2-deficient islets. GKA-induced Fbln5 upregulation in the islets was blunted by a glucokinase inhibitor, K_ATP channel opener, Ca²⁺ channel blocker and calcineurin inhibitor, while it was augmented by harmine, a dual-specificity tyrosine phosphorylation-regulated kinase (DYRK) 1 A inhibitor. Although deletion of Fbln5 in mice had no significant effects on the glucose tolerance or β-cell functions, adenovirus-mediated Fbln5 overexpression increased glucose-stimulated insulin secretion in INS-1 rat insulinoma cells. Since the islet Fbln5 expression is regulated through a glucokinase/K_ATP channel/calcineurin/nuclear factor of activated T cells (NFAT) pathway crucial for the maintenance of β-cell functions, further investigation of Fbln5 functions in the islets is warranted.

Fibulin-4 is essential for maintaining arterial wall integrity in conduit but not muscular arteries

Homozygous or compound heterozygous mutations in fibulin-4 (FBLN4) lead to autosomal recessive cutis laxa type 1B (ARCL1B), a multisystem disorder characterized by significant cardiovascular abnormalities, including abnormal elastin assembly, arterial tortuosity, and aortic aneurysms. We sought to determine the consequences of a human disease-causing mutation in FBLN4 (E57K) on the cardiovascular system and vascular elastic fibers in a mouse model of ARCL1B. Fbln4E57K/E57K mice were hypertensive and developed arterial elongation, tortuosity, and ascending aortic aneurysms. Smooth muscle cell organization within the arterial wall of large conducting vessels was abnormal, and elastic fibers were fragmented and had a moth-eaten appearance. In contrast, vessel wall structure and elastic fiber integrity were normal in resistance/muscular arteries (renal, mesenteric, and saphenous). Elastin cross-linking and total elastin content were unchanged in large or small arteries, whereas elastic fiber architecture was abnormal in large vessels. While the E57K mutation did not affect Fbln4 mRNA levels, FBLN4 protein was lower in the ascending aorta of mutant animals compared to wild-type arteries but equivalent in mesenteric arteries. We found a differential role of FBLN4 in elastic fiber assembly, where it functions mainly in large conduit arteries. These results suggest that elastin assembly has different requirements depending on vessel type. Normal levels of elastin cross-links in mutant tissue call into question FBLN4's suggested role in mediating lysyl oxidase-elastin interactions. Future studies investigating tissue-specific elastic fiber assembly may lead to novel therapeutic interventions for ARCL1B and other disorders of elastic fiber assembly.

Differential proteomics analysis of low- and high-grade of astrocytoma using iTRAQ quantification

Astrocytoma is one of the most common types of brain tumor, which is histologically and clinically classified into four grades (I–IV): I (pilocytic astrocytoma), II (diffuse astrocytoma), III (anaplastic astrocytoma), and IV (glioblastoma multiforme). A higher grade astrocytoma represents a worse prognosis and is more aggressive. In this study, we compared the differential proteome profile of astrocytoma from grades I to IV. The protein samples from clinical specimens of grades I, II, III, and IV astrocytoma were analyzed by two-dimensional liquid chromatography–tandem mass spectrometry and isobaric tags for relative and absolute quantitation and quantification. A total of 2,190 proteins were identified. Compared to grade I astrocytoma, 173 (12.4%), 304 (14%), and 462 (21.2%) proteins were aberrantly expressed in grades II, III, and IV, respectively. By bioinformatics analysis, the cell proliferation, invasion, and angiogenesis-related pathways increase from low- to high-grade of astrocytoma. Five differentially expressed proteins were validated by Western blot. Within them, matrix metalloproteinase-9 and metalloproteinase inhibitor 1 were upregulated in glioblastoma multiforme group; whereas fibulin-2 and -5 were downregulated in grade II/III/IV astrocytoma, and the negative expression was significantly associated with advanced clinical stage. Functional analysis showed that both fibulin-2 and -5 may exert an antitumor effect by inhibiting cell proliferation, in vitro migration/invasion in glioma cells. New molecular biomarkers are likely to be used for accurate classification of astrocytoma and likely to be the target for drug development.

Hypoxia and Transforming Growth Factor β Cooperate to Induce Fibulin-5 Expression in Pancreatic Cancer

The deposition of extracellular matrix (ECM) is a defining feature of pancreatic ductal adenocarcinoma (PDA), where ECM signaling can promote cancer cell survival and epithelial plasticity programs. However, ECM signaling can also limit PDA tumor growth by producing cytotoxic levels of reactive oxygen species. For example, excess fibronectin stimulation of α5β1 integrin on stromal cells in PDA results in reduced angiogenesis and increased tumor cell apoptosis because of oxidative stress. Fibulin-5 (Fbln5) is a matricellular protein that blocks fibronectin-integrin interaction and thus directly limits ECM-driven reactive oxygen species production and supports PDA progression. Compared with normal pancreatic tissue, Fbln5 is expressed abundantly in the stroma of PDA; however, the mechanisms underlying the stimulation of Fbln5 expression in PDA are undefined. Using in vitro and in vivo approaches, we report that hypoxia triggers Fbln5 expression in a TGF-β- and PI3K-dependent manner. Pharmacologic inhibition of TGF-β receptor, PI3K, or protein kinase B (AKT) was found to block hypoxia-induced Fbln5 expression in mouse embryonic fibroblasts and 3T3 fibroblasts. Moreover, tumor-associated fibroblasts from mouse PDA were also responsive to TGF-β receptor and PI3K/AKT inhibition with regard to suppression of Fbln5. In genetically engineered mouse models of PDA, therapy-induced hypoxia elevated Fbln5 expression, whereas pharmacologic inhibition of TGF-β signaling reduced Fbln5 expression. These findings offer insight into the signaling axis that induces Fbln5 expression in PDA and a potential strategy to block its production.

Fibulin-5 localisation in human endometrial cancer shifts from epithelial to stromal with increasing tumour grade, and silencing promotes endometrial epithelial cancer cell proliferation

Endometrial cancer is the most common invasive gynaecological malignancy. While endocrine, genetic and inflammatory factors are thought to contribute to its pathogenesis, its precise etiology and molecular regulators remain poorly understood. Fibulin-5 is an extracellular matrix (ECM) protein that inhibits cell growth and invasion in several cancer cell types and is downregulated in a number of types of human cancer. However, it is unknown whether fibulin-5 plays a role in endometrial tumourigenesis. In the current report, the expression and localisation of fibulin-5 in type I endometrioid human endometrial cancers of grades (G) 1-3 was investigated using reverse transcription-quantitative polymerase chain reaction and immunohistochemistry. Fibulin-5 mRNA was found to be significantly reduced in whole tumour tissues from women across G1-3 compared with benign endometrium (P<0.0001). Consistently, fibulin-5 protein was also reduced in the tumour epithelial compartment across increasing tumour grades. By contrast, increased protein localisation to the tumour stroma was observed with increasing grade. Knockdown by small interfering RNA in Ishikawa endometrial epithelial cancer cells expressing fibulin-5 stimulated cell adhesion and proliferation in vitro. Fibulin-5 mRNA expression in Ishikawa cells was induced by transforming growth factor-β and fibulin-5 in turn activated extracellular signal-regulated kinases (ERK1/2), suggesting that it may act via the mitogen-activated protein kinase pathway. In summary, the present study identified fibulin-5 as a downregulated ECM gene in human endometrial cancer and observed a shift from epithelial to stromal protein localisation with increasing tumour grade in women. These data suggest that loss of fibulin-5 function may promote endometrial cancer progression by enhancing epithelial cell adhesion and proliferation.

Fibulin-4 is a novel Wnt/β-Catenin pathway activator in human osteosarcoma

Fibulin-4, an extracellular glycoprotein implicated in connective tissue development and elastic fiber formation, draws increasing focuses in cancer research. However, little is known about the underlying oncogenic roles of Fibulin-4 in human osteosarcoma (OS). In this study, by immunohistochemical analysis, upregulated expression of Fibulin-4 was found in the OS clinical specimens and cell lines compared to their normal counterparts. Fibulin-4 was positively correlated with the T stage of OS patients, and the proliferation index Ki67. Based on informatics analysis and functional verification, microRNA-137 was identified as a potential upstream regulator of Fibulin-4. Knockdown of Fibulin-4 or introduction of microRNA-137 inhibited cell proliferation and promoted cell apoptosis, and adverse effects were observed by overexpression of Fibulin-4. Furthermore, the tumor-suppressive functions of microRNA-137 were markedly abolished by restoration of Fibulin-4 expression in OS cells. Mechanistically, Fibulin-4 activated Wnt/β-Catenin pathway and promoted the expression of its downstream targets, including CCND2, c-Myc and VEGF. Taken together, Fibulin-4 plays critical neoplastic roles in tumor growth of human OS by activating Wnt/β-Catenin signaling and may represent a potential therapeutic target.

Pelvic Organ Support in Animals with Partial Loss of Fibulin-5 in the Vaginal Wall

Compromise of elastic fiber integrity in connective tissues of the pelvic floor is most likely acquired through aging, childbirth-associated injury, and genetic susceptibility. Mouse models of pelvic organ prolapse demonstrate systemic deficiencies in proteins that affect elastogenesis. Prolapse, however, does not occur until several months after birth and is thereby acquired with age or after parturition. To determine the impact of compromised levels of fibulin-5 (Fbln5) during adulthood on pelvic organ support after parturition and elastase-induced injury, tissue-specific conditional knockout (cKO) mice were generated in which doxycycline (dox) treatment results in deletion of Fbln5 in cells that utilize the smooth muscle α actin promoter-driven reverse tetracycline transactivator and tetracycline responsive element-Cre recombinase (i.e., Fbln5f/f/SMA++-rtTA/Cre+, cKO). Fbln5 was decreased significantly in the vagina of cKO mice compared with dox-treated wild type or controls (Fbln5f/f/SMA++-rtTA/Cre-/-). In controls, perineal body length (PBL) and bulge increased significantly after delivery but declined to baseline values within 6-8 weeks. Although overt prolapse did not occur in cKO animals, these transient increases in PBL postpartum were amplified and, unlike controls, parturition-induced increases in PBL (and bulge) did not recover to baseline but remained significantly increased for 12 wks. This lack of recovery from parturition was associated with increased MMP-9 and nondetectable levels of Fbln5 in the postpartum vagina. This predisposition to prolapse was accentuated by injection of elastase into the vaginal wall in which overt prolapse occurred in cKO animals, but rarely in controls. Taken together, our model system in which Fbln5 is conditionally knock-downed in stromal cells of the pelvic floor results in animals that undergo normal elastogenesis during development but lose Fbln5 as adults. The results indicate that vaginal fibulin-5 during development is crucial for baseline pelvic organ support and is also important for protection and recovery from parturition- and elastase-induced prolapse.

Fibulin-5 downregulates Ki-67 and inhibits proliferation and invasion of breast cancer cells

Fibulins not only function as molecular bridges within the cellular microenvironment but also influence cell behavior. Thus, fibulins may contribute to create a permissive microenvironment for tumor growth but can also stimulate different mechanisms that may impede tumor progression. This is the case with Fibulin-5, which has been shown to display both tumor-promoting and tumor-protective functions by mechanisms that are not totally defined. We show new evidence on the tumor-protective functions displayed by Fibulin-5 in MCF-7, T47D and MDA-MB-231 breast cancer cells including the inhibition of invasion and proliferation capacity and hampering the ability to form mammospheres. Reduction in the level of phosphorylation of Ser residues involved in the nuclear translocation of β-catenin may underlie these antitumor effects. We also found that Fibulin-5 reduces the level of expression of Ki-67, a nuclear protein associated with cell proliferation. Moreover, reduction in Fibulin-5 expression corresponds to an increase of Ki-67 detection in breast tissue samples. Overall, our data provide new insights into the influence of Fibulin-5 to modify breast cancer cell behavior and contribute to better understand the connections between fibulins and cancer.

Co-expression of fibulin-5 and VEGF165 increases long-term patency of synthetic vascular grafts seeded with autologous endothelial cells

Small caliber synthetic vascular grafts are commonly used for bypass surgery and dialysis access sites but have high failure rates because of neointima formation and thrombosis. Seeding synthetic grafts with endothelial cells (ECs) provides a biocompatible surface that may prevent graft failure. However, EC detachment following exposure to blood flow still remains a major obstacle in the development of biosynthetic grafts. We tested the hypothesis that induced expression by the seeded EC, of vascular endothelial growth factor165 (VEGF165) and of fibulin-5, an extracellular matrix glycoprotein that has a crucial role in elastin fiber organization and increase EC adherence to surfaces, may improve long-term graft patency. Autologous ECs were isolated from venous segments, and were transduced with retroviral vectors expressing fibulin-5 and VEGF165. The modified cells were seeded on expanded polytetrafluoroethylene (ePTFE) grafts and implanted in a large animal model. Three months after transplantation, all grafts seeded with modified EC were patent on a selective angiography, whereas only a third of the control grafts were patent. Similar results were shown at 6 months. Thus, seeding ePTFE vascular grafts with genetically modified EC improved long-term small caliber graft patency. The biosynthetic grafts may provide a novel therapeutic modality for patients with peripheral vascular disease and patients requiring vascular access for hemodialysis.

The Extracellular Matrix in Bronchopulmonary Dysplasia: Target and Source

Bronchopulmonary dysplasia (BPD) is a common complication of preterm birth that contributes significantly to morbidity and mortality in neonatal intensive care units. BPD results from life-saving interventions, such as mechanical ventilation and oxygen supplementation used to manage preterm infants with acute respiratory failure, which may be complicated by pulmonary infection. The pathogenic pathways driving BPD are not well-delineated but include disturbances to the coordinated action of gene expression, cell-cell communication, physical forces, and cell interactions with the extracellular matrix (ECM), which together guide normal lung development. Efforts to further delineate these pathways have been assisted by the use of animal models of BPD, which rely on infection, injurious mechanical ventilation, or oxygen supplementation, where histopathological features of BPD can be mimicked. Notable among these are perturbations to ECM structures, namely, the organization of the elastin and collagen networks in the developing lung. Dysregulated collagen deposition and disturbed elastin fiber organization are pathological hallmarks of clinical and experimental BPD. Strides have been made in understanding the disturbances to ECM production in the developing lung, but much still remains to be discovered about how ECM maturation and turnover are dysregulated in aberrantly developing lungs. This review aims to inform the reader about the state-of-the-art concerning the ECM in BPD, to highlight the gaps in our knowledge and current controversies, and to suggest directions for future work in this exciting and complex area of lung development (patho)biology.

Expression of fibulin-5 in the skin of patients with rectal prolapse

AIM

Components of connective tissue other than collagen have been found to be involved in patients with rectal prolapse. The organization of elastic fibres differs between controls and subsets of patients with rectal prolapse, and their importance for maintaining the structural and functional integrity of the pelvic floor has been demonstrated in transgenic mice, with animals which have a null mutation in fibulin-5 (Fbln5(i/i)) developing prolapse. This study aimed to compare fibulin-5 expression in the skin of patients with and without rectal prolapse.

METHOD

Between January 2013 and February 2014, skin specimens were obtained during surgery from 20 patients with rectal prolapse and from 21 without prolapse undergoing surgery for other indications. Fibroblasts from the skin were cultured and the level of fibulin-5 expression was determined on cultured fibroblasts, isolated from these specimens by quantitative real-time polymerase chain reaction. Immunohistochemistry was performed on fixed tissue specimens to assess fibulin-5 expression.

RESULTS

Fibulin-5 mRNA expression and fibulin-5 staining intensity were significantly lower in young male patients with rectal prolapse compared with age-matched controls [fibulin-5 mean ± SD mRNA relative units, 1.1 ± 0.41 vs 0.53 ± 0.22, P = 0.001; intensity score, median (range), 2 (0-3) vs 1 (0-3), P = 0.05]. There were no significant differences in the expression of fibulin-5 in women with rectal prolapse compared with controls.

CONCLUSION

Fibulin-5 may be implicated in the aetiology of rectal prolapse in a subgroup of young male patients.

Fibulin-5 is upregulated in decidualized human endometrial stromal cells and promotes primary human extravillous trophoblast outgrowth

Interactions between the highly invasive trophoblasts and the maternal uterine decidual extracellular matrix (ECM) are crucial in the determination of a successful pregnancy. Fibulin-5 (FBLN5) is a member of the fibulin family that alters cell adhesive and invasive properties and is expressed in human villous cytotrophoblasts. We aimed to determine the expression and immunolocalization of FBLN5 in human first trimester decidua and examine the effect of FBLN5 in trophoblast invasion in vitro using a first trimester placental villous outgrowth assay. We demonstrated that FBLN5 mRNA expression is upregulated in response to cAMP-mediated decidualization of primary human endometrial stromal cells, although FBLN5 itself does not enhance decidualization. We reported for the first time, FBLN5 protein production in first trimester decidual cells and also co-localization to HLAG-positive EVTs in first trimester decidua. Consequently, we investigated the effects of exogenous FBLN5 on placental villous outgrowth in vitro and demonstrated that FBLN5 promotes EVT migration/invasion. This is the first study to identify FBLN5 in decidualized human endometrial stromal cells, first trimester decidua and EVT and determine a functional role for FBLN5 in human EVTs, suggesting that decidual and or EVT-derived FBLN5 regulates EVT invasion and placentation in women.

Effect of fibulin-5 on adhesion, migration and invasion of hepatocellular carcinoma cells via an integrin-dependent mechanism

AIM: To elucidate the role of fibulin-5 (FBLN-5) as a suppressor of hepatocellular carcinoma (HCC) cell metastasis via integrin.

METHODS: The expression of FBLN-5 was determined by immunohistochemistry in 140 HCC samples and matched normal tissues, and was further confirmed by RT-PCR and Western blot analyses in various cell lines. Recombinant FBLN-5 was expressed in Escherichia coli BL21(DE3), purified and used in cell attachment assays. Expression of a specific plasmid or a specific siRNA in HCC cells resulted in the overexpression or knockdown of FBLN-5, respectively. Further, the migration and invasion of HCC cells were investigated using the Boyden chamber and transwell assays. The concentration of secreted matrix metalloproteinase 7 (MMP-7) was determined using ELISA.

RESULTS: FBLN-5 expression was found to be downregulated in HCC. Its expression was significantly correlated with advanced tumor metastasis; this was indicative of poor 5-year overall survival. Recombinant full-length human FBLN-5 promoted the attachment of HCC cells via integrins: it inhibited HCC cell adhesion and migration to fibronectin in a concentration-dependent manner. It also inhibited HCC cell migration and invasion through an integrin-binding arginine-glycine-aspartic acid (RGD) motif by downregulating MMP-7.

CONCLUSION: These results suggest that lower FBLN-5 expression is an important indicator of poor survival and that FBLN-5 inhibits HCC motility via an integrin-dependent mechanism. RGD-dependent suppression of MMP-7 by FBLN-5 might contribute to the development of new therapeutic strategies for HCC.

Effect of Fibulin-5 on cell proliferation and invasion in human gastric cancer patients

OBJECTIVES

To explore the effect of Fibulin-5 expression on cell proliferation and invasion in human gastric cancer patients.

METHODS

Fibulin-5 expression was detected in 56 samples of surgically resected gastric cancer and paired noncancerous tissues using qRT-PCR and immunoblotting. Fibulin-5 was knocked down by Fibulin-5 shRNA in MGC-803 cells, then BrdU cell proliferation and transwell invasion assays were used to determine cell proliferation and invasion.

RESULTS

The level of Fibulin-5 mRNA in gastric cancer tissues was significantly higher as compared with that in normal tumor-adjacent tissues (P<0.05). Otherwise, the level of Fibulin-5 protein in cancer and noncancerous tissues was consistent with mRNA expression (P<0.05). Fibulin-5 protein expression in tumor tissues with poorly differentiated, lymph node metastasis and advanced TNM tumor stage was significantly higher (P<0.05, respectively). Fibulin-5 was obviously knocked down by Fibulin-5 shRNA (P<0.05), and Fibulin-5 knockdown significantly inhibited cell proliferation and invasion in MGC-803 cells (P<0.05, respectively).

CONCLUSIONS

The high-expression of Fibulin-5 is associated with the malignant clinicopathologic parameters in gastric cancer and Fibulin-5 knockdown inhibits cell proliferation and invasion in MGC-803 cells, suggesting Fibulin-5 may act as a key factor in the progression of gastric cancer.

Fibulin-5 is a tumour suppressor inhibiting cell migration and invasion in ovarian cancer

AIMS

Fibulin-5 is an extracellular matrix (ECM) glycoprotein which has a role in the organisation and stabilisation of ECM structures and regulating cell proliferation and tumourigenesis. Here, the expression of fibulin-5 and its functional effects on the migration and invasion of ovarian cancer cells were assessed.

METHODS

Expression of fibulin-5 was detected in 44 ovarian tumour tissues by qRT-PCR, Western blotting and immunohistochemistry. We performed cell migration and invasion assays, and cell cycle analysis in fibulin-5 transfected SKOV3 (SKOV3-FBLN5) cells and the parental SKOV3 cells. We further examined the expression of three tissue inhibitors of metalloproteinases (TIMPs) and seven matrix metalloproteinases (MMPs) by RT-PCR.

RESULTS

mRNA and protein expression of fibulin-5 were down-regulated (0.05-fold and 0.1-fold) in ovarian carcinomas compared with control tissues (p<0.01 and p=0.022). In wound-healing and invasion assays, significantly fewer SKOV3-FBLN5 cells than SKOV3 control cells migrated and invaded (39.1%, p=0.046 and 70%, p=0.03, respectively), which was reversed by siRNA-treatment. Overexpression of fibulin-5 induced G2/M arrest and increased cyclin B1, CDC2 and CDC25C. Expression of TIMP-2 (0.56-fold), MMP-3 (0.43-fold) and MMP-13 (0.18-fold) was lower and MMP-9 expression (2.20-fold) was higher in SKOV3-FBLN5 cells than in control cells.

CONCLUSIONS

Fibulin-5 is significantly down-regulated in ovarian carcinoma and acts as a tumour suppressor by inhibiting the migration and invasion of ovarian cancer cells.

Fibulin-5 regulates keloid-derived fibroblast-like cells through integrin beta-1

OBJECTIVE

Keloid scar is pathological tissue that appears after skin injury, and that is more aggressive than hypertrophic scars. Keloid scars are characterized by increased proliferation of fibroblast-like cells (FLCs) and the accumulation of extracellular matrix, mainly collagen. Fibulin-5, a glycoprotein secreted by many cell types, is a component of the extracellular matrix. We investigated the effect of fibulin-5 on the adhesion and proliferation of FLCs derived from keloid scars and the role of integrin beta-1 in these activities.

METHODS

Fibroblast-like cells were isolated from six keloid scars and cultured on plates coated with fibulin-5 or with gelatin. Cells were incubated for 72-96 h to examine proliferation rates and incubated for 240 min, with washings at 20, 40, 60, 90, 120, 180 min, to assess adhesion rates. To examine the role of integrin beta-1, the anti-human integrin beta-1 (CD29) antibody was added to the culture medium.

RESULTS

Fibroblast-like cells from keloids cultured on a fibulin-5-coated surface showed a significantly reduced proliferation rate and a delayed adhesion rate, compared to cells cultured on gelatin-coated dishes. Adherence of these cells to fibulin-5 pre-coated wells was significantly reduced in the presence of anti-human integrin beta-1 (CD29) antibodies. Our current findings are similar to previously observed reduced proliferation in vascular smooth muscle cells overexpressing fibulin-5. We did not test the effects of fibulin-5 on normal fibroblasts.

CONCLUSION

This study demonstrates the pivotal role of the extracellular protein, fibulin-5, on the adhesion and proliferation of human keloid-derived cells, through binding to integrin beta-1.

Fibulin-5 inhibits hepatocellular carcinoma cell migration and invasion by down-regulating matrix metalloproteinase-7 expression

Background

Fibulin-5 has been considered as a tumor suppressor through inhibiting tumor growth and invasion. Reduced expression of Fibulin-5 is frequently observed in various human cancers. In this study, we investigate the clinical significance of Fibulin-5 and its role in hepatocellular carcinoma (HCC) cell migration and invasion.

Methods

The expression of Fibulin-5 was evaluated by qRT-PCR and immunoblotting in HCC and matched noncancerous tissues. Fibulin-5 was over-expressed or knocked down by a retrovirus-mediated expression plasmid or a specific siRNA in HCC cells. Boyden chamber and Transwell assays were used to test HCC cell migration and invasion. Immunostaining was performed to determine matrix metalloproteinase-7 (MMP-7) expression in HCC specimens. MMP-7 retroviruses and siRNA were used to alter MMP-7 expression in HCC cells.

Results

In our study, the expression levels of Fibulin-5 protein and mRNA were down-regulated in HCC tissues as compared with those in matched noncancerous tissues. Reduced expression of Fibulin-5 was observed in all HCC cell lines (HepG2, SMMC-7721, MHCC97L, Hep3B, MHCC97H and HCC-LM3) as compare with that in a non-transformed hepatic cell line (LO2). Low expression of Fibulin-5 was significantly correlated with poor prognostic features including multiple tumor nodes, venous infiltration, high Edmondson-Steiner grading and advanced tumor-node-metastasis (TNM) tumor stage. Furthermore, we demonstrated that Fibulin-5 was a novel independent prognostic marker for predicting 5-year survival of HCC patients. Our in vitro studies showed that Fibulin-5 overexpression inhibited HCC cell migration and invasion. While Fibulin-5 knockdown increased the number of migrated and invaded HCC cells. Fibulin-5 negatively regulated MMP-7 abundance in HCC cells. Moreover, the inverse correlation between Fibulin-5 and MMP-7 expressions was observed in HCC tissues. Mechanistically, we disclosed that MMP-7 knockdown reduced the number of migrated and invaded HCC cells. Restoring MMP-7 expression abrogated the suppressive effect of Fibulin-5 on HCC cell migration and invasion in vitro, suggesting that Fibulin-5 exerted its anti-metastatic function, at least in part, by down-regulating the expression of MMP-7 in HCC cells.

Conclusions

These results indicate that Fibulin-5 may serve as a prognostic biomarker and inhibits HCC invasion and metastasis by suppressing MMP-7 expression.

Fibulins and their role in cardiovascular biology and disease

Fibulins are a group of extracellular matrix proteins of which many are present in high amounts in the cardiovascular system. They share common biochemical properties and are often found in relation to basement membranes or elastic fibers. Observations in humans with specific mutations in fibulin genes, together with results from genetically engineered mice and data from human cardiovascular tissue suggest that the fibulin family of proteins play important functional roles in the cardiovascular system. Moreover, fibulin-1 circulates in high concentrations in plasma and may function as a cardiovascular disease marker.

Regulation of fibulin-2 gene expression by integrin α3β1 contributes to the invasive phenotype of transformed keratinocytes

The laminin-binding integrin α3β1 is highly expressed in epidermal keratinocytes, where it regulates both cell-autonomous and paracrine functions that promote wound healing and skin tumorigenesis. However, the roles for α3β1 in regulating gene expression programs that control the behaviors of immortalized or transformed keratinocytes remain underexplored. In the current study, we used a microarray approach to identify genes that are regulated by α3β1 in immortalized keratinocytes. α3β1-Responsive genes included several genes that are involved in extracellular matrix proteolysis or remodeling, including fibulin-2 and secreted protein acidic and rich in cysteine. However, α3β1-dependent induction of specific target genes was influenced by the genetic lesion that triggered immortalization, as α3β1-dependent fibulin-2 expression occurred in cells immortalized by either SV40 large T antigen or p53-null mutation, whereas α3β1-dependent expression of secreted protein acidic and rich in cysteine occurred only in the former cells. Interestingly, quantitative PCR arrays did not reveal strong patterns of α3β1-dependent gene expression in freshly isolated primary keratinocytes, suggesting that this regulation is acquired during immortalization. p53-null keratinocytes transformed with oncogenic RasV12 retained α3β1-dependent fibulin-2 expression, and RNAi-mediated knockdown of fibulin-2 in these cells reduced invasion, although not their tumorigenic potential. These findings demonstrate a prominent role for α3β1 in immortalized/transformed keratinocytes in regulating fibulin-2 and other genes that promote matrix remodeling and invasion.

Functional analysis of candidate genes in 2q13 deletion syndrome implicates FBLN7 and TMEM87B deficiency in congenital heart defects and FBLN7 in craniofacial malformations

Recurrent 2q13 deletion syndrome is associated with incompletely penetrant severe cardiac defects and craniofacial anomalies. We used an atypical, overlapping 1.34 Mb 2q13 deletion in a patient with pathogenically similar congenital heart defects (CHD) to narrow the putative critical region for CHD to 474 kb containing six genes. To determine which of these genes is responsible for severe cardiac and craniofacial defects noted in the patients with the deletions, we used zebrafish morpholino knockdown to test the function of each orthologue during zebrafish development. Morpholino-antisense-mediated depletion of fibulin-7B, a zebrafish orthologue of fibulin-7 (FBLN7), resulted in cardiac hypoplasia, deficient craniofacial cartilage deposition and impaired branchial arch development. TMEM87B depletion likewise resulted in cardiac hypoplasia but with preserved branchial arch development. Depletion of both fibulin-7B and TMEM87B resulted in more severe defects of cardiac development, suggesting that their concurrent loss may enhance the risk of a severe cardiac defect. We postulate that heterozygous loss of FBLN7 and TMEM87B account for some of the clinical features, including cardiac defects and craniofacial abnormalities associated with 2q13 deletion syndrome.

Oncogenic fibulin-5 promotes nasopharyngeal carcinoma cell metastasis through the FLJ10540/AKT pathway and correlates with poor prognosis

Background

Nasopharyngeal carcinoma (NPC) is known for its high metastatic potential and locoregional recurrence, although the molecular alterations that are driving NPC metastasis remain unclear at this time. This study aimed to examine the expression of fibulin-5 in NPC, correlate the results with clinicopathological variables and survival, and to investigate the role of fibulin-5 in human NPC cell lines.

Material and Methods

Standard semi-quantitative-RT-PCR, quantitative-RT-PCR, immunoblotting, and immunohistochemistry were used to investigate the mRNA and protein expression profiles of fibulin-5 in normal and NPC tissues. Immunohistochemistry of fibulin-5 was correlated with clinicopathological characteristics by univariate analyses. NPC cells overexpressing fibulin-5 or fibulin-5-siRNA cells were generated by stable transfection to characterize the molecular mechanisms of fibulin-5-elicited cell growth and metastasis.

Results

Our results demonstrated that fibulin-5 overexpression in NPC specimens and significantly correlated with advanced tumor metastasis indicating a poor 5-year overall survival. Fibulin-5 was mainly expressed in the nucleus in human NPC specimens and cell lines. Functionally, fibulin-5 overexpression yielded fast growth in NPC cells. In addition, fibulin-5 promotes cell metastasis in NPC cells through increased FLJ10540 and phosphor-AKT activity. In contrast, siRNA depletion of fibulin-5 suppressed FLJ10540 expression and phosphor-AKT activity. Suppression of either fibulin-5 or FLJ10540 can cause significant inhibition with regards to cell motility in NPC cells. Finally, immunohistochemical analysis of human aggressive NPC specimens showed a significant and positive correlation between fibulin-5 and FLJ10540 expression.

Conclusion

Higher fibulin-5 expression is not only an important indicator of poor survival, but also contributes to the development of new therapeutic strategies in the FLJ10540/AKT pathway for NPC treatment.

Upregulated WAVE3 expression is essential for TGF-β-mediated EMT and metastasis of triple-negative breast cancer cells

Breast cancer is the second leading cause of cancer death in women in the United States. Metastasis accounts for the death of ~90 % of these patients, yet the mechanisms underlying this event remain poorly defined. WAVE3 belongs to the WASP/WAVE family of actin-binding proteins that play essential roles in regulating cell morphology, actin polymerization, cytoskeleton remodeling, cell motility, and invasion. Accordingly, we demonstrated previously that WAVE3 promotes the acquisition of invasive and metastatic phenotypes by human breast cancers. Herein, we show that transforming growth factor-β (TGF-β) selectively and robustly induced the expression of WAVE3 in metastatic breast cancer cells, but not in their nonmetastatic counterparts. Moreover, the induction of WAVE3 expression in human and mouse triple-negative breast cancer cells (TNBCs) by TGF-β likely reflects its coupling to microRNA expression via a Smad2- and β3 integrin-dependent mechanism. We further demonstrate the requirement for WAVE3 expression in mediating the initiation of epithelial-mesenchymal transition (EMT) programs stimulated by TGF-β. Indeed, stable depletion of WAVE3 expression in human TNBC cells prevented TGF-β from inducing EMT programs and from stimulating the proliferation, migration, and the formation of lamellipodia in metastatic TNBC cells. Lastly, we observed WAVE3 deficiency to abrogate the outgrowth of TNBC cell organoids in 3-dimensional organotypic cultures as well as to decrease the growth and metastasis of 4T1 tumors produced in syngeneic Balb/C mice. Indeed, WAVE3 deficiency significantly reduced the presence of sarcomatoid morphologies indicative of EMT phenotypes in pulmonary TNBC tumors as compared to those detected in their parental counterparts. Collectively, these findings indicate the necessity for WAVE3 expression and activity during EMT programs stimulated by TGF-β; they also suggest that measures capable of inactivating WAVE3 may play a role in alleviating metastasis stimulated by TGF-β.

LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis

Latent transforming growth factor-beta-1 binding protein-2 (LTBP-2) is a protein of ill-defined function associated with elastic fibers during elastinogenesis. Although LTBP-2 binds fibrillin-1, fibulin-5, and heparin/heparan sulfate, molecules critical for normal elastic fiber assembly, it does not interact directly with elastin or its precursor, tropoelastin. We investigated the modulating effect of LTBP-2 on two key interactions of tropoelastin during elastinogenesis a) with fibulin-5 and b) with heparan sulfate (using heparin). Firstly, using solid phase assays we showed that LTBP-2 bound fibulin-5 (Kd=26.47±5.68 nM) with an affinity similar to that of the tropoelastin-fibulin-5 interaction (Kd=24.66±5.64 nM). Then using a competitive binding assay we showed that LTBP-2 inhibited the tropoelastin-fibulin-5 interaction in a dose dependent manner with almost complete inhibition obtained with 5-fold molar excess of LTBP-2. Interestingly, a fragment of LTBP-2 containing the fibulin-5 binding sequence only partially inhibited the tropoelasin-fibulin-5 interaction suggesting that LTBP-2 was directly blocking only the C-terminal tropoelastin binding site on fibulin-5 and indirectly blocking tropoelastin binding to the N-terminal region. In parallel experiments heparin was shown to have minor inhibitory effects on fibulin-5 interactions with tropoelastin and LTBP-2. However, LTBP-2 was shown to significantly inhibit the binding of heparin to tropoelastin with 50% inhibition achieved with 10 fold molar excess of LTBP-2. Confocal microscopy of fibroblast matrix showed strong co-distribution of LTBP-2 with fibulin-5 and fibrillin-1 and partial co-distribution with heparan sulfate proteoglycans, perlecan and syndecan-4. Also addition of exogenous LTBP-2 to ear cartilage chondrocyte cultures blocked elastinogenesis in a concentration-dependent manner. Overall the results indicate that LTBP-2 may have a negative regulatory role during elastic fiber assembly, perhaps in displacing elastin microassemblies from complexes with fibulin-5 and/or cell surface heparan sulfate proteoglycans.

Fibulin-3-mediated inhibition of epithelial-to-mesenchymal transition and self-renewal of ALDH+ lung cancer stem cells through IGF1R signaling

Fibulins (FBLNs), a family of extracellular matrix proteins, have recently been shown to act as tumor suppressors or activators in different cancers, and the underlying molecular mechanisms of their action in cancer remain unclear. We have previously shown that the expression of FBLN3 is suppressed by promoter hypermethylation and is associated with invasiveness in aggressive non-small cell lung cancer. In this study, we evaluated the roles and signaling mechanism of FBLN3 in lung cancer stem cells (CSCs). Forced expression of FBLN3 suppressed invasion and migration of lung adenocarcinoma cells and decreased the expression of epithelial-to-mesenchymal transition (EMT) activators, including N-cadherin and Snail. Stemness activities of lung adenocarcinoma cells were also suppressed by FBLN3 as indicated by a decrease in spheroid formation and the levels of stemness markers such as Sox2 and β-catenin. These effects of FBLN3 were mediated by the glycogen synthase kinase-3β, GSK3β/β-catenin pathway, and the upstream regulators of GSK3β, including phosphoinositide 3-kinase (PI3K)/AKT and insulin-like growth factor-1 receptor (IGF1R), were inactivated by FBLN3. Moreover, IGF1R was shown to be a direct target of FBLN3, which competitively inhibited insulin-like growth factor (IGF) action. To confirm the effect of FBLN3 on lung CSCs, aldehyde dehydrogenase-positive (ALDH+) A549 lung CSCs were sorted and treated with recombinant FBLN3 protein. FBLN3 clearly suppressed EMT, stemness activity and the over-activated IGF1R/PI3K/AKT/GSK3β pathway of the ALDH+ CSC subpopulation. In addition, injection of recombinant FBLN3 protein around subcutaneous xenografts established with ALDH+ CSCs in athymic nude mice significantly suppressed tumor growth and progression. Overall, our results show that FBLN3 suppresses both EMT and self-renewal of the lung CSCs by modulating the IGF1R/PI3K/AKT/GSK3β pathway and that FBLN3 would be useful as an alternative CSC therapy.

Epigenetic inactivation of EFEMP1 is associated with tumor suppressive function in endometrial carcinoma

OBJECTIVE

EFEMP1, the epidermal growth factor-containing fibulin-like extracellular matrix protein 1, functions as an oncogene or a tumor suppressor depending on the cancer types. In this study, we aim to determine whether EFEMP1 affects the tumorigenesis and progression of endometrial carcinoma.

METHODS

The expression of EFEMP1 was investigated using immunohistochemistry in a panel of normal endometrium (n = 40), atypical hyperplasia (n = 10) and endometrial carcinoma tissues (n = 84). Methylation status of the EFEMP1 promoter was detected by methylation-specific PCR (MSP) and bisulphite genomic sequencing. Up- or down-regulation of EFEMP1 were achieved by stable or transient transfection with pCMV6/GFP/Neo-EFEMP1 or pGPU6/GFP/Neo-shEFEMP1 respectively. Effects of EFEMP1 on tumor proliferation, invasion and migration were evaluated by MTT, plate colony formation, Transwell and wound healing assay. The nude mouse tumor xenograft assay was used to investigate function of EFEMP1 in vivo.

RESULTS

Compared with normal endometrium (32/40) and atypical hyperplasia (7/10), EFEMP1 expression was much lower in endometrial carcinoma tissues (16/84) (P<0.001 and P = 0.02). EFEMP1 promoter was hypermethylated in endometrial carcinoma tissues (67%) as compared to normal tissue (10%) and down-regulation of EFEMP1 was associated with promoter hypermethylation. Treatment with 5-aza-2'-deoxycytidine (5-aza-dC) and/or trichostatin A (TSA) altered EFEMP1 methylation status, and restored EFEMP1 expression. Moreover, EFEMP1 decreased secretion of MMPs and inhibited tumor cell proliferation, metastasis and invasion in vitro and suppressed tumorigenesis in nude mice. Besides, EFEMP1 increased expression of E-cadherin and suppressed expression of vimentin in endometrial carcinoma.

CONCLUSION

EFEMP1 is a new candidate tumor suppressor gene in endometrial carcinoma, and is frequently silenced by promoter hypermethylation. It could inhibit tumor growth and invasion both in vitro and in vivo. Our findings propose that targeting EFEMP1 might offer future clinical utility in endometrial carcinoma.