Severe absence of intra-orbital fat in a patient with orbital venous malformation: A case report.

BACKGROUND: The orbital venous malformation is quite common in orbital diseases. Clinically, it is usually characterized by proptosis. However, among patients with distensible venous malformations, if the lesions continuously progress, they may induce enlargement of the orbital bone or orbital lipoatrophy, which in turn leads to enophthalmos. CASE SUMMARY: Here, we report a patient who presented with enophthalmos and had a severe absence of intra-orbital fat secondary to orbital venous malformation. The patient was a 66-year-old female with a 20-year history of enophthalmos. Hertel exophthalmometry readings in a relaxed upright position were 4 mm OD and 13 mm OS with a 97 mm base. It was determined that she had positional "proptosis". Physical examination also revealed a bulging mass on her hard palate. Computed tomographic scan and magnetic resonance imaging showed an expansion of the right orbit with local bony defects and multiple soft-tissue masses. CONCLUSION: Long-term lack of awareness about the presence of orbital venous malformations, persistent venous congestion could lead to compression of the orbital fat, which in turn induces atrophy or the absence of intra-orbital fat.

Progranulin/EphA2 axis: A novel oncogenic mechanism in bladder cancer.

The growth factor progranulin plays a critical role in bladder cancer by modulating tumor cell motility and invasion. Progranulin regulates remodeling of the actin cytoskeleton by interacting with drebrin, an actin binding protein that regulates tumor growth. We previously discovered that progranulin depletion inhibits epithelial-to-mesenchymal transition and markedly reduces in vivo tumor growth. Moreover, progranulin depletion sensitizes urothelial cancer cells to cisplatin treatment, further substantiating a pro-survival function of progranulin. Until recently, the progranulin signaling receptor remained unidentified, precluding a full understanding of progranulin action in tumor cell biology. We recently identified EphA2, a member of a large family of receptor tyrosine-kinases, as the functional receptor for progranulin. However, it is not established whether EphA2 plays an oncogenic role in bladder cancer. Here we demonstrate that progranulin, and not ephrin-A1, the canonical ligand for EphA2, is the predominant EphA2 ligand in bladder cancer. Progranulin evoked Akt- and Erk1/2-mediated EphA2 phosphorylation at Ser897, which could drive bladder tumorigenesis. We discovered that EphA2 depletion severely blunted progranulin-dependent motility and anchorage-independent growth, and sensitized bladder cancer cells to cisplatin treatment. We further defined the mechanisms of progranulin/EphA2-dependent motility by identifying liprin-α1 as a novel progranulin-dependent EphA2 interacting protein and establishing its critical role in cell motility. The discovery of EphA2 as the functional signaling receptor for progranulin and the identification of novel downstream effectors offer a new avenue for understanding the underlying mechanism of progranulin action and may constitute novel clinical and therapeutic targets in bladder cancer.

Discoidin Domain Receptor 1 functionally interacts with the IGF-I system in bladder cancer.

Bladder cancer is one of the most common and aggressive cancers and, regardless of the treatment, often recurs and metastasizes. Thus, a better understanding of the mechanisms regulating urothelial tumorigenesis is critical for the design and implementation of rational therapeutic strategies. We previously discovered that the IGF-IR axis is critical for bladder cancer cell motility and invasion, suggesting a possible role in bladder cancer progression. However, IGF-IR depletion in metastatic bladder cancer cells only partially inhibited anchorage-independent growth. Significantly, metastatic bladder cancer cells have decreased IGF-IR levels but overexpressed the insulin receptor isoform A (IR-A), suggesting that the latter may play a more prevalent role than the IGF-IR in bladder tumor progression. The collagen receptor DDR1 cross-talks with both the IGF-IR and IR in breast cancer, and previous data suggest a role of DDR1 in bladder cancer. Here, we show that DDR1 is expressed in invasive and metastatic, but not in papillary, non-invasive bladder cancer cells. DDR1 is phosphorylated upon stimulation with IGF-I, IGF-II, and insulin, co-precipitates with the IGF-IR, and the IR-A and transient DDR1 depletion severely inhibits IGF-I-induced motility. We further demonstrate that DDR1 interacts with Pyk2 and non-muscle myosin IIA in ligands-dependent fashion, suggesting that it may link the IGF-IR and IR-A to the regulation of F-actin cytoskeleton dynamics. Similarly to the IGF-IR, DDR1 is upregulated in bladder cancer tissues compared to healthy tissue controls. Thus, our findings provide the first characterization of the molecular cross-talk between DDR1 and the IGF-I system and could lead to the identification of novel targets for therapeutic intervention in bladder cancer. Moreover, the expression profiles of IGF-IR, IR-A, DDR1, and downstream effectors could serve as a novel biomarker signature with diagnostic and prognostic significance.

Analysis of Progranulin-Mediated Akt and MAPK Activation.

Progranulin has emerged in recent years as an important regulator of various biological functions including cell proliferation, wound healing, motility, and protection from apoptosis. Progranulin is also critical for transformation as established in several cancer models.Progranulin biological responses elicit through the activation of the Akt and MAPK pathways, which are critical for progranulin downstream signaling.In this chapter various experimental approaches aiming at detecting progranulin-mediated Akt and MAPK activation will be discussed.

The perlecan-interacting growth factor progranulin regulates ubiquitination, sorting, and lysosomal degradation of sortilin.

Despite extensive clinical and experimental studies over the past decades, the pathogenesis and progression to the castration-resistant stage of prostate cancer remains largely unknown. Progranulin, a secreted growth factor, strongly binds the heparin-sulfate proteoglycan perlecan, and counteracts its biological activity. We established that progranulin acts as an autocrine growth factor and promotes prostate cancer cell motility, invasion, and anchorage-independent growth. Progranulin was overexpressed in prostate cancer tissues vis-à-vis non-neoplastic tissues supporting the hypothesis that progranulin may play a key role in prostate cancer progression. However, progranulin's mode of action is not well understood and proteins regulating progranulin signaling have not been identified. Sortilin, a single-pass type I transmembrane protein of the Vps10 family, binds progranulin in neurons and targets progranulin for lysosomal degradation. Significantly, in DU145 and PC3 cells, we detected very low levels of sortilin associated with high levels of progranulin production and enhanced motility. Restoring sortilin expression decreased progranulin levels, inhibited motility and anchorage-independent growth and destabilized Akt. These results demonstrated a critical role for sortilin in regulating progranulin and suggest that sortilin loss may contribute to prostate cancer progression. Here, we provide the novel observation that progranulin downregulated sortilin protein levels independent of transcription. Progranulin induced sortilin ubiquitination, internalization via clathrin-dependent endocytosis and sorting into early endosomes for lysosomal degradation. Collectively, these results constitute a regulatory feed-back mechanism whereby sortilin downregulation ensures sustained progranulin-mediated oncogenesis.

Mechanisms of Progranulin Action and Regulation in Genitourinary Cancers.

The growth factor progranulin has emerged in recent years as a critical regulator of transformation in several cancer models, including breast cancer, glioblastomas, leukemias, and hepatocellular carcinomas. Several laboratories, including ours, have also demonstrated an important role of progranulin in several genitourinary cancers, including ovarian, endometrial, cervical, prostate, and bladder tumors, where progranulin acts as an autocrine growth factor thereby modulating motility and invasion of transformed cells. In this review, we will focus on the mechanisms of action and regulation of progranulin signaling in genitourinary cancers with a special emphasis on prostate and bladder tumors.

Suppression of progranulin expression inhibits bladder cancer growth and sensitizes cancer cells to cisplatin.

We have recently demonstrated a critical role for progranulin in bladder cancer. Progranulin contributes, as an autocrine growth factor, to the transformed phenotype by modulating Akt-and MAPK-driven motility, invasion and anchorage-independent growth. Progranulin also induces F-actin remodeling by interacting with the F-actin binding protein drebrin. In addition, progranulin is overexpressed in invasive bladder cancer compared to normal tissue controls, suggesting that progranulin might play a key role in driving the transition to the invasive phenotype of urothelial cancer. However, it is not established whether targeting progranulin could have therapeutic effects on bladder cancer. In this study, we stably depleted urothelial cancer cells of endogenous progranulin by shRNA approaches and determined that progranulin depletion severely inhibited the ability of tumorigenic urothelial cancer cells to migrate, invade and grow in anchorage-independency. We further demonstrate that progranulin expression is critical for tumor growth in vivo, in both xenograft and orthotopic tumor models. Notably, progranulin levels correlated with response to cisplatin treatment and were upregulated in bladder tumors. Our data indicate that progranulin may constitute a novel target for therapeutic intervention in bladder tumors. In addition, progranulin may serve as a novel biomarker for bladder cancer.

A novel role for drebrin in regulating progranulin bioactivity in bladder cancer.

We recently established a critical role for the growth factor progranulin in bladder cancer insofar as progranulin promotes urothelial cancer cell motility and contributes, as an autocrine growth factor, to the transformed phenotype by modulating invasion and anchorage-independent growth. In addition, progranulin expression is upregulated in invasive bladder cancer tissues compared to normal controls. However, the molecular mechanisms of progranulin action in bladder cancer have not been fully elucidated. In this study, we searched for novel progranulin-interacting proteins using pull-down assays with recombinant progranulin and proteomics. We discovered that drebrin, an F-actin binding protein, bound progranulin in urothelial cancer cells. We characterized drebrin function in urothelial cancer cell lines and showed that drebrin is critical for progranulin-dependent activation of the Akt and MAPK pathways and modulates motility, invasion and anchorage-independent growth. In addition, drebrin regulates tumor formation in vivo and its expression is upregulated in bladder cancer tissues compared to normal tissue controls. Our data are translationally relevant as indicate that drebrin exerts an essential functional role in the regulation of progranulin action and may constitute a novel target for therapeutic intervention in bladder tumors. In addition, drebrin may serve as novel biomarker for bladder cancer.

Novel cross talk between IGF-IR and DDR1 regulates IGF-IR trafficking, signaling and biological responses.

The insulin-like growth factor-I receptor (IGF-IR), plays a key role in regulating mammalian development and growth, and is frequently deregulated in cancer contributing to tumor initiation and progression. Discoidin domain receptor 1 (DDR1), a collagen receptor tyrosine-kinase, is as well frequently overexpressed in cancer and implicated in cancer progression. Thus, we investigated whether a functional cross-talk between the IGF-IR and DDR1 exists and plays any role in cancer progression.Using human breast cancer cells we found that DDR1 constitutively associated with the IGF-IR. However, this interaction was enhanced by IGF-I stimulation, which promoted rapid DDR1 tyrosine-phosphorylation and co-internalization with the IGF-IR. Significantly, DDR1 was critical for IGF-IR endocytosis and trafficking into early endosomes, IGF-IR protein expression and IGF-I intracellular signaling and biological effects, including cell proliferation, migration and colony formation. These biological responses were inhibited by DDR1 silencing and enhanced by DDR1 overexpression.Experiments in mouse fibroblasts co-transfected with the human IGF-IR and DDR1 gave similar results and indicated that, in the absence of IGF-IR, collagen-dependent phosphorylation of DDR1 is impaired.These results demonstrate a critical role of DDR1 in the regulation of IGF-IR action, and identify DDR1 as a novel important target for breast cancers that overexpress IGF-IR.

Sortilin regulates progranulin action in castration-resistant prostate cancer cells.

The growth factor progranulin is as an important regulator of transformation in several cellular systems. We have previously demonstrated that progranulin acts as an autocrine growth factor and stimulates motility, proliferation, and anchorage-independent growth of castration-resistant prostate cancer cells, supporting the hypothesis that progranulin may play a critical role in prostate cancer progression. However, the mechanisms regulating progranulin action in castration-resistant prostate cancer cells have not been characterized. Sortilin, a single-pass type I transmembrane protein of the vacuolar protein sorting 10 family, binds progranulin in neurons and negatively regulates progranulin signaling by mediating progranulin targeting for lysosomal degradation. However, whether sortilin is expressed in prostate cancer cells and plays any role in regulating progranulin action has not been established. Here, we show that sortilin is expressed at very low levels in castration-resistant PC3 and DU145 cells. Significantly, enhancing sortilin expression in PC3 and DU145 cells severely diminishes progranulin levels and inhibits motility, invasion, proliferation, and anchorage-independent growth. In addition, sortilin overexpression negatively modulates Akt (protein kinase B, PKB) stability. These results are recapitulated by depleting endogenous progranulin in PC3 and DU145 cells. On the contrary, targeting sortilin by short hairpin RNA approaches enhances progranulin levels and promotes motility, invasion, and anchorage-independent growth. We dissected the mechanisms of sortilin action and demonstrated that sortilin promotes progranulin endocytosis through a clathrin-dependent pathway, sorting into early endosomes and subsequent lysosomal degradation. Collectively, these results point out a critical role for sortilin in regulating progranulin action in castration-resistant prostate cancer cells, suggesting that sortilin loss may contribute to prostate cancer progression.

Decorin differentially modulates the activity of insulin receptor isoform A ligands.

The proteoglycan decorin, a key component of the tumor stroma, regulates the action of several tyrosine-kinase receptors, including the EGFR, Met and the IGF-IR. Notably, the action of decorin in regulating the IGF-I system differs between normal and transformed cells. In normal cells, decorin binds with high affinity to both the natural ligand IGF-I and the IGF-I receptor (IGF-IR) and positively regulates IGF-IR activation and downstream signaling. In contrast, in transformed cells, decorin negatively regulates ligand-induced IGF-IR activation, downstream signaling and IGF-IR-dependent biological responses. Whether decorin may bind another member of the IGF-I system, the insulin receptor A isoform (IR-A) and its cognate ligands, insulin, IGF-II and proinsulin, have not been established. Here we show that decorin bound with high affinity insulin and IGF-II and, to a lesser extent, proinsulin and IR-A. We utilized as a cell model system mouse embryonic fibroblasts homozygous for a targeted disruption of the Igf1r gene (designated R(-) cells) which were stably transfected with a human construct harboring the IR-A isoform of the receptor. Using these R(-)/IR-A cells, we demonstrate that decorin did not affect ligand-induced phosphorylation of the IR-A but enhanced IR-A downregulation after prolonged IGF-II stimulation without affecting insulin and proinsulin-dependent effects on IR-A stability. In addition, decorin significantly inhibited IGF-II-mediated activation of the Akt pathways, without affecting insulin and proinsulin-dependent signaling. Notably, decorin significantly inhibited IGF-II-mediated cell proliferation of R(-)/IR-A cells but affected neither insulin- nor proinsulin-dependent mitogenesis. Collectively, these results suggest that decorin differentially regulates the action of IR-A ligands. Decorin preferentially inhibits IGF-II-mediated biological responses but does not affect insulin- or proinsulin-dependent signaling. Thus, decorin loss may contribute to tumor initiation and progression in malignant neoplasms which depend on an IGF-II/IR-A autocrine loop.

Beta-blockers versus corticosteroids in the treatment of infantile hemangioma: an evidence-based systematic review.

BACKGROUND: The efficacy and safety of beta-blockers versus corticosteroids in the treatment of infantile hemangiomas (IHs) is controversial. This study aimed to summarize evidence described in the literature and to assess the quality of studies involving beta-blockers and corticosteroids for the treatment of cutaneous IHs. METHODS: Comparative studies were collected from 15 online electronic databases, including OVID Medline, PubMed, ISI Web of Science, CENTRAL, CNKI, ChiCTR, JPCTR, CTRIndia, IranCTR, SLCTR, ISRCTRN, NLCTR, GCTR, ANCTR, ClinicalTrial. gov, and associated references. Studies without a control group were excluded, and the remaining studies were assessed by two reviewers independently using the Downs & Black scale for reported quality. The main areas assessed in the included studies were volume changes, overall improvement in appearance, eye function, and adverse events. RESULTS: Ten comparative studies were included with a total of 419 children. A meta-analysis was not performed due to the considerable heterogeneity across studies. Some evidence showed that beta-blockers are superior to steroids in reducing volume and improving the overall appearance of IHs, such as lightening of the color and flattening of the surface. Conclusions regarding improved eye function and adverse events were divided, and no consensus has been reached on the superiority of one treatment over another. No episodes of severe-onset asthma, hypotension, or bradycardia occurred in the beta-blocker treatment due to the rigorous exclusion of patients with contraindications. CONCLUSIONS: Available studies indicate that beta-blockers are an alternative option to corticosteroids for IH treatment with respect to volume shrinkage and improvement in appearance. No evidence has shown a significant difference in improved eye function and adverse events between beta-blockers and corticosteroids in the treatment of IH; indeed, there is a lack of well-designed, high-quality randomized control trials.

Proline-rich tyrosine kinase 2 (Pyk2) regulates IGF-I-induced cell motility and invasion of urothelial carcinoma cells.

The insulin-like growth factor receptor I (IGF-IR) plays an essential role in transformation by promoting cell growth and protecting cancer cells from apoptosis. We have recently demonstrated that the IGF-IR is overexpressed in invasive bladder cancer tissues and promotes motility and invasion of urothelial carcinoma cells. These effects require IGF-I-induced Akt- and MAPK-dependent activation of paxillin. The latter co-localizes with focal adhesion kinases (FAK) at dynamic focal adhesions and is critical for promoting motility of urothelial cancer cells. FAK and its homolog Proline-rich tyrosine kinase 2 (Pyk2) modulate paxillin activation; however, their role in regulating IGF-IR-dependent signaling and motility in bladder cancer has not been established. In this study we demonstrate that FAK was not required for IGF-IR-dependent signaling and motility of invasive urothelial carcinoma cells. On the contrary, Pyk2, which was strongly activated by IGF-I, was critical for IGF-IR-dependent motility and invasion and regulated IGF-I-dependent activation of the Akt and MAPK pathways. Using immunofluorescence and AQUA analysis we further discovered that Pyk2 was overexpressed in bladder cancer tissues as compared to normal tissue controls. Significantly, in urothelial carcinoma tissues there was increased Pyk2 localization in the nuclei as compared to normal tissue controls. These results provide the first evidence of a specific Pyk2 activity in regulating IGF-IR-dependent motility and invasion of bladder cancer cells suggesting that Pyk2 and the IGF-IR may play a critical role in the invasive phenotype in urothelial neoplasia. In addition, Pyk2 and the IGF-IR may serve as novel biomarkers with diagnostic and prognostic significance in bladder cancer.

Decorin antagonizes IGF receptor I (IGF-IR) function by interfering with IGF-IR activity and attenuating downstream signaling.

We have recently discovered that the insulin-like growth factor receptor I (IGF-IR) is up-regulated in human invasive bladder cancer and promotes migration and invasion of transformed urothelial cells. The proteoglycan decorin, a key component of the tumor stroma, can positively regulate the IGF-IR system in normal cells. However, there are no available data on the role of decorin in modulating IGF-IR activity in transformed cells or in tumor models. Here we show that the expression of decorin inversely correlated with IGF-IR expression in low and high grade bladder cancers (n = 20 each). Decorin bound with high affinity IGF-IR and IGF-I at distinct sites and negatively regulated IGF-IR activity in urothelial cancer cells. Nanomolar concentrations of decorin promoted down-regulation of IRS-1, one of the critical proteins of the IGF-IR pathway, and attenuated IGF-I-dependent activation of Akt and MAPK. This led to decorin-evoked inhibition of migration and invasion upon IGF-I stimulation. Notably, decorin did not cause down-regulation of the IGF-IR in bladder, breast, and squamous carcinoma cells. This indicates that decorin action on the IGF-IR differs from its known activity on other receptor tyrosine kinases such as the EGF receptor and Met. Our results provide a novel mechanism for decorin in negatively modulating both IGF-I and its receptor. Thus, decorin loss may contribute to increased IGF-IR activity in the progression of bladder cancer and perhaps other forms of cancer where IGF-IR plays a role.

The insulin-like growth factor receptor I promotes motility and invasion of bladder cancer cells through Akt- and mitogen-activated protein kinase-dependent activation of paxillin.

The insulin-like growth factor receptor I (IGF-IR) plays an essential role in transformation by promoting cell growth and protecting cancer cells from apoptosis. Aberrant IGF-IR signaling is implicated in several types of tumors, including carcinomas of the lung, breast, prostate, pancreas, liver, and colon. However, the contribution of the IGF-IR to the development of the transformed phenotype in urothelial cells has not been clearly established. In this study we demonstrated that the IGF-IR is overexpressed in invasive bladder cancer tissues compared with nonmalignant controls. We have investigated the role of the IGF-IR in bladder cancer by using urothelial carcinoma-derived 5637 and T24 cells. Although activation of the IGF-IR did not appreciably affect their growth, it did promote migration and stimulate in vitro wound closure and invasion. These effects required the activation of the Akt and Mitogen-activated protein kinase (MAPK) pathways as well as IGF-I-induced Akt- and MAPK-dependent phosphorylation of paxillin, which relocated at dynamic focal adhesions and was necessary for promoting motility in bladder cancer cells. Our results provide the first evidence for a role of the IGF-IR in motility and invasion of bladder cancer cells and support the hypothesis that the IGF-IR may play a critical role in the establishment of the invasive phenotype in urothelial neoplasia. Thus, the IGF-IR may also serve as a novel biomarker for bladder cancer.

Mechanism of growth inhibition by MicroRNA 145: the role of the IGF-I receptor signaling pathway.

MicroRNA 145 (miR145) has been proposed as a tumor suppressor. It was previously shown that miR145 targets the 3' UTR of the insulin receptor substrate-1 (IRS-1) and dramatically inhibits the growth of colon cancer cells. miR145 also targets the type 1 insulin-like growth factor receptor (IGF-IR). We show here that an IRS-1 lacking its 3' UTR is no longer down-regulated by miR145 and rescues colon cancer cells from miR145-induced inhibition of growth. An IGF-IR resistant to miR145 (again by elimination of its 3' UTR) is not down-regulated by miR145 but fails to rescue colon cancer cells from growth inhibition. These and other results, taken together, indicate that down-regulation of IRS-1 plays a significant role in the tumor suppressor activity of miR145.

Proepithelin is an autocrine growth factor for bladder cancer.

The growth factor proepithelin functions as an important regulator of proliferation and motility. Proepithelin is overexpressed in a great variety of cancer cell lines and clinical specimens of breast, ovarian and renal cancer, as well as glioblastomas. Using recombinant proepithelin on 5637 transitional cell carcinoma-derived cells, we have shown previously that proepithelin plays a critical role in bladder cancer by promoting motility of bladder cancer cells. In this study, we used the ONCOMINE database and gene microarray analysis tool to analyze proepithelin expression in several bladder cancer microarray studies. We found a statistically significant increase in proepithelin messenger RNA expression in bladder cancers vis-à-vis non-neoplastic tissues, and this was associated with pathologic and prognostic parameters. Targeted downregulation of proepithelin in T24 transitional carcinoma cells with small hairpin RNA inhibited both Akt and mitogen-activated protein kinase pathways, severely reduced the ability of T24 cells to proliferate in the absence of serum and inhibited migration, invasion and wound healing. In support of these in vitro results, we discovered that proepithelin expression was significantly upregulated in invasive bladder cancer tissues compared with normal urothelium. In addition, proepithelin was secreted in the urine, where it was detectable by immunoblotting and enzyme-linked immunosorbent assay. Collectively, these results support the hypothesis that proepithelin may play a critical role as an autocrine growth factor in the establishment and progression of bladder cancer and suggest that proepithelin may prove a novel biomarker for the diagnosis and prognosis of bladder neoplasms.

Proepithelin regulates prostate cancer cell biology by promoting cell growth, migration, and anchorage-independent growth.

The growth factor proepithelin has recently emerged as an important regulator of transformation in several physiological and pathological systems. In this study, we determined the biological roles of proepithelin in prostate cancer cells using purified human recombinant proepithelin as well as proepithelin-depletion strategies. Proepithelin promoted the migration of androgen-dependent and -independent human prostate cancer cells; androgen-independent DU145 cells were the more responsive. In these cells, proepithelin additionally stimulated wound closure, invasion, and promotion of cell growth in vitro. These effects required the activation of both the Akt and mitogen-activated protein kinase pathways. We have analyzed proepithelin expression levels in different available prostate cancer microarray studies using the Oncomine database and found a statistically significant increase in proepithelin mRNA expression levels in prostate cancers compared with nonneoplastic controls. Notably, depletion of endogenous proepithelin by siRNA and antisense strategies impaired the ability of DU145 cells to grow and migrate after serum withdrawal and inhibited anchorage-independent growth. Our results provide the first evidence for a role of proepithelin in stimulating the migration, invasion, proliferation, and anchorage-independent growth of prostate cancer cells. This study supports the hypothesis that proepithelin may play a critical role as an autocrine growth factor in the establishment and initial progression of prostate cancer. Furthermore, proepithelin may prove to be a useful clinical marker for the diagnosis of prostate tumors.

Adiponectin protects against angiotensin II or tumor necrosis factor alpha-induced endothelial cell monolayer hyperpermeability: role of cAMP/PKA signaling.

OBJECTIVE: Angiotensin II (Ang II) and tumor necrosis factor (TNF)-alpha levels increase endothelial permeability, and we hypothesized that adiponectin suppressed these responses in a cAMP-dependent manner. METHODS AND RESULTS: The effect of adiponectin on transendothelial electric resistance (TEER) and diffusion of albumin through human umbilical vein and bovine aortic endothelial cell monolayers induced by Ang II (100 nmol/L) or TNF-alpha (5 ng/mL) was measured. Treatment with the globular domain of adiponectin (3 mug/mL) for 16 hours abrogated the adverse TEER effect of TNF-alpha (-35 versus -12 Omega/cm(2) at 45 minutes, P<0.05) and Ang II (-25 versus -5 Omega/cm(2) at 45 minutes, P<0.01) and partially suppressed the increased diffusion of albumin with Ang II (40% versus 10% change, P<0.05) or TNF-alpha (40% versus 20% change, P<0.05). Full-length adiponectin also suppressed Ang II-induced monolayer hyperpermeability. Adiponectin treatment also suppressed Ang II-induced increased actin stress fiber development, intercellular gap formation, and beta-tubulin disassembly. Adiponectin increased cAMP levels, and its effects were abrogated by inhibition of adenylyl cyclase or cAMP-dependent protein kinase signaling. CONCLUSIONS: Adiponectin protects the endothelial monolayer from Ang II or TNF-alpha-induced hyperpermeability by modulating microtubule and cytoskeleton stability via a cAMP/ PKA signaling cascade.

Adiponectin suppresses IkappaB kinase activation induced by tumor necrosis factor-alpha or high glucose in endothelial cells: role of cAMP and AMP kinase signaling.

Adiponectin is a protein secreted from adipocytes that exhibits salutary effects in the vascular endothelium by signaling mechanisms that are not well understood. In obesity-related disease states and type 2 diabetes, circulating substances, including tumor necrosis factor-alpha (TNFalpha) and high glucose, activate IkappaB kinase (IKK)beta and reduce the abundance of its substrate, inhibitor of kappaB (IkappaB)alpha, leading to nuclear translocation of the transcription factor NF-kappaB and stimulation of an inflammatory signaling cascade closely associated with endothelial dysfunction. The present study demonstrates that the globular domain of adiponectin (gAd) potently suppresses the activation of IKKbeta by either TNFalpha or high glucose in human umbilical vein endothelial cells and ameliorates the associated loss of IkappaBalpha protein. Interestingly, activation of AMP kinase was substantially more effective than cAMP signaling in suppressing high glucose-induced IKKbeta activity, whereas both pathways were comparably active in suppressing the TNFalpha-induced increase in IKKbeta. Both cAMP/protein kinase A signaling and activation of the AMP kinase pathway played a role in the suppression by gAd of TNFalpha- and high glucose-mediated IKKbeta activation. These findings support an important role for adiponectin in anti-inflammatory signaling in the endothelium and also imply that multiple pathways are involved in the cellular effects of adiponectin.