ANGPTL4 modulates vascular junction integrity by integrin signaling and disruption of intercellular VE-cadherin and claudin-5 clusters.Blood. 2011;118:3990-4002. [PMID: 21841165 DOI: 10.1182/blood-2011-01-328716]

ANGIOPOIETIN-LIKE 4 CORRELATES WITH RESPONSE TO INTRAVITREAL RANIBIZUMAB INJECTIONS IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION

PURPOSE

To investigate whether the aqueous angiopoietin-like 4 (ANGPTL4) level correlates with clinical features in neovascular age-related macular degeneration (AMD).

METHODS

The control and study groups consisted of all consecutive patients who received senile cataract surgery or intravitreal ranibizumab injection for treatment-naïve neovascular AMD, respectively. The AMD group received 3 monthly ranibizumab injections followed by monthly pro re nata for at least 12 months. Aqueous ANGPTL4 and vascular endothelial growth factor (VEGF) were measured at baseline and 4 weeks after the first injection. In the AMD group, best-corrected visual acuity, lesion area by fluorescein angiography, and central subfield thickness were measured at baseline and at 12 months.

RESULTS

The AMD group (30 eyes) had higher baseline aqueous ANGPTL4 and VEGF levels than those of the control group (32 eyes) (both P < 0.001). Four weeks after the first injection, VEGF in the patients with AMD had dropped significantly (P < 0.001). Baseline ANGPTL4 correlated with the lesion area at baseline and at 12 months (P < 0.05, respectively), and also correlated with the frequency of anti-VEGF injections during 12 months (P = 0.008).

CONCLUSION

Aqueous ANGPTL4 levels correlated with the lesion area and anti-VEGF treatment frequency. Angiopoietin-like 4 may be a potential diagnostic and/or therapeutic biomarker in the neovascular AMD.

Angiopoietin-like 4 promotes osteosarcoma cell proliferation and migration and stimulates osteoclastogenesis

BACKGROUND

Osteosarcoma is the most common primary bone cancer in children and young adults. It is highly aggressive and patients that present with metastasis have a poor prognosis. Angiopoietin-like 4 (ANGPTL4) drives the progression and metastasis of many solid tumours, but has not been described in osteosarcoma tissue. ANGPTL4 also enhances osteoclast activity, which is required for osteosarcoma growth in bone. We therefore investigated the expression and function of ANGPTL4 in human osteosarcoma tissue and cell lines.

METHODS

Expression of ANGPTL4 in osteosarcoma tissue microarrays was determined by immunohistochemistry. Hypoxic secretion of ANGPTL4 was tested by ELISA and Western blot. Regulation of ANGPTL4 by hypoxia-inducible factor (HIF) was investigated using isoform specific HIF siRNA (HIF-1α, HIF-2α). Effects of ANGPTL4 on cell proliferation, migration (scratch wound assay), colony formation and osteoblastogenesis were assessed using exogenous ANGPTL4 or cells stably transfected with ANGPTL4. Osteoclastogenic differentiation of CD14+ monocytes was assessed by staining for tartrate-resistant acid phosphatase (TRAP), bone resorption was assessed by lacunar resorption of dentine.

RESULTS

ANGPTL4 was immunohistochemically detectable in 76/109 cases. ANGPTL4 was induced by hypoxia in 6 osteosarcoma cell lines, under the control of the HIF-1α transcription factor. MG-63 cells transfected with an ANGPTL4 over-expression plasmid exhibited increased proliferation and migration capacity and promoted osteoclastogenesis and osteoclast-mediated bone resorption. Individually the full-length form of ANGPTL4 could increase MG-63 cell proliferation, whereas N-terminal ANGPTL4 mediated the other pro-tumourigenic phenotypes.

CONCLUSIONS

This study describes a role(s) for ANGPTL4 in osteosarcoma and identifies ANGPTL4 as a treatment target that could potentially reduce tumour progression, inhibit angiogenesis, reduce bone destruction and prevent metastatic events.

Oleate-induced PTX3 promotes head and neck squamous cell carcinoma metastasis through the up-regulation of vimentin

The association between metabolic diseases and the risk of developing cancer is emerging. However, the impact of long pentraxin-3 (PTX3) on dyslipidemia-associated tumor metastasis remains unknown. In this study, we found that oleate induced PTX3 expression and secretion through the activation of Akt/NF-κB pathway in head and neck squamous cell carcinomas (HNSCCs). The activation of NF-κB was essential for the oleate-induced stabilization of PTX3 mRNA. In addition, both the depletion of PTX3 and the inhibition of NF-κB significantly inhibited oleate-induced tumor cell migration and invasion. The enhancement of binding between tumor and endothelial cells was observed in oleate-treated cells but not in the depletion and neutralization of PTX3 with siPTX3 and anti-PTX3 antibodies, respectively. The levels of oleate-induced epithelial-mesenchymal transition (EMT) markers, such as vimentin and MMP-3, were significantly reduced in PTX3-depleted cells. Knocking down vimentin also repressed oleate-induced HNSCC invasion. Furthermore, the depletion of PTX3 blocked the oleate-primed metastatic seeding of tumor cells in the lungs. These results demonstrate that oleate enhances HNSCC metastasis through the PTX3/vimentin signaling axes. The inhibition of PTX3 could be a potential strategy for the treatment of dyslipidemia-mediated HNSCC metastasis.

Organ-specific metastasis of breast cancer: molecular and cellular mechanisms underlying lung metastasis

BACKGROUND

Breast cancer (BC) is the most common type of cancer in women and the second cause of cancer-related mortality world-wide. The majority of BC-related deaths is due to metastasis. Bone, lung, brain and liver are the primary target sites of BC metastasis. The clinical implications and mechanisms underlying bone metastasis have been reviewed before. Given the fact that BC lung metastasis (BCLM) usually produces symptoms only after the lungs have been vastly occupied with metastatic tumor masses, it is of paramount importance for diagnostic and prognostic, as well as therapeutic purposes to comprehend the molecular and cellular mechanisms underlying BCLM. Here, we review current insights into the organ-specificity of BC metastasis, including the role of cancer stem cells in triggering BC spread, the traveling of tumor cells in the blood stream and their migration across endothelial barriers, their adaptation to the lung microenvironment and the initiation of metastatic colonization within the lung.

CONCLUSIONS

Detailed understanding of the mechanisms underlying BCLM will shed a new light on the identification of novel molecular targets to impede daunting pulmonary metastases in patients with breast cancer.

Absence of ANGPTL4 in adipose tissue improves glucose tolerance and attenuates atherogenesis

Alterations in ectopic lipid deposition and circulating lipids are major risk factors for developing cardiometabolic diseases. Angiopoietin-like protein 4 (ANGPTL4), a protein that inhibits lipoprotein lipase (LPL), controls fatty acid (FA) uptake in adipose and oxidative tissues and regulates circulating triacylglycerol-rich (TAG-rich) lipoproteins. Unfortunately, global depletion of ANGPTL4 results in severe metabolic abnormalities, inflammation, and fibrosis when mice are fed a high-fat diet (HFD), limiting our understanding of the contribution of ANGPTL4 in metabolic disorders. Here, we demonstrate that genetic ablation of ANGPTL4 in adipose tissue (AT) results in enhanced LPL activity, rapid clearance of circulating TAGs, increased AT lipolysis and FA oxidation, and decreased FA synthesis in AT. Most importantly, we found that absence of ANGPTL4 in AT prevents excessive ectopic lipid deposition in the liver and muscle, reducing novel PKC (nPKC) membrane translocation and enhancing insulin signaling. As a result, we observed a remarkable improvement in glucose tolerance in short-term HFD-fed AT-specific Angptl4-KO mice. Finally, lack of ANGPTL4 in AT enhances the clearance of proatherogenic lipoproteins, attenuates inflammation, and reduces atherosclerosis. Together, these findings uncovered an essential role of AT ANGPTL4 in regulating peripheral lipid deposition, influencing whole-body lipid and glucose metabolism and the progression of atherosclerosis.

Angiopoietin-Like Proteins in Angiogenesis, Inflammation and Cancer

Altered expression of secreted factors by tumor cells or cells of the tumor microenvironment is a key event in cancer development and progression. In the last decade, emerging evidences supported the autocrine and paracrine activity of the members of the Angiopoietin-like (ANGPTL) protein family in angiogenesis, inflammation and in the regulation of different steps of carcinogenesis and metastasis development. Thus, ANGPTL proteins become attractive either as prognostic or predictive biomarkers, or as novel target for cancer treatment. Here, we outline the current knowledge about the functions of the ANGPTL proteins in angiogenesis, cancer progression and metastasis. Moreover, we discuss the most recent evidences sustaining their role as prognostic or predictive biomarkers for cancer therapy. Although the role of ANGPTL proteins in cancer has not been fully elucidated, increasing evidence suggest their key effects in the proliferative and invasive properties of cancer cells. Moreover, given the common overexpression of ANGPTL proteins in several aggressive solid tumors, and their role in tumor cells and cells of the tumor microenvironment, the field of research about ANGPTL proteins network may highlight new potential targets for the development of future therapeutic strategies.

Molecular Fingerprint for Terminal Abdominal Aortic Aneurysm Disease

Background

Clinical decision making in abdominal aortic aneurysms (AAA) relies completely on diameter. At this point, improved decision tools remain an unmet medical need. Our goal was to identify changes at the molecular level specifically leading up to AAA rupture.

Methods and Results

Aortic wall tissue specimens were collected during open elective (eAAA; n=31) or emergency repair of ruptured AAA (rAAA; n=17), and gene expression was investigated using microarrays. Identified candidate genes were validated with quantitative real‐time polymerase chain reaction in an independent sample set (eAAA: n=46; rAAA: n=18). Two gene sets were identified, 1 set containing 5 genes linked to terminal progression, that is, positively associated with progression of larger AAA, and with rupture (HILPDA,ANGPTL4,LOX,SRPX2,FCGBP), and a second set containing 5 genes exclusively upregulated in rAAA (ADAMTS9,STC1,GFPT2,GAL3ST4,CCL4L1). Genes in both sets essentially associated with processes related to impaired tissue remodeling, such as angiogenesis and adipogenesis. In gene expression experiments we were able to show that upregulated gene expression for identified candidate genes is unique for AAA. Functionally, the selected upregulated factors converge at processes coordinated by the canonical HIF‐1α signaling pathway and are highly expressed in fibroblasts but not inflammatory cells of the aneurysmatic wall. Histological quantification of angiogenesis and exploration of the HIF‐1α network in rAAA versus eAAA shows enhanced microvessel density but also clear activation of the HIF‐1α network in rAAA.

Conclusions

Our study shows a specific molecular fingerprint for terminal AAA disease. These changes appear to converge at activation of HIF‐1α signaling in mesenchymal cells. Aspects of this cascade might represent targets for rupture risk assessment.

Angiopoietin-like 4 Is a Wnt Signaling Antagonist that Promotes LRP6 Turnover

Angiopoietin-like 4 (ANGPTL4) is a secreted signaling protein that is implicated in cardiovascular disease, metabolic disorder, and cancer. Outside of its role in lipid metabolism, ANGPTL4 signaling remains poorly understood. Here, we identify ANGPTL4 as a Wnt signaling antagonist that binds to syndecans and forms a ternary complex with the Wnt co-receptor Lipoprotein receptor-related protein 6 (LRP6). This protein complex is internalized via clathrin-mediated endocytosis and degraded in lysosomes, leading to attenuation of Wnt/β-catenin signaling. Angptl4 is expressed in the Spemann organizer of Xenopus embryos and acts as a Wnt antagonist to promote notochord formation and prevent muscle differentiation. This unexpected function of ANGPTL4 invites re-interpretation of its diverse physiological effects in light of Wnt signaling and may open therapeutic avenues for human disease.

Epigenetic silencing of the dual-role signal mediator, ANGPTL4 in tumor tissues and its overexpression in the urothelial carcinoma microenvironment

Urothelial carcinoma (UC) carcinogenesis has been hypothesized to occur through epigenetic repression of tumor-suppressor genes (TSGs). By quantitative real-time polymerase chain reaction array, we found that one potential TSG, angiopoietin-like 4 (ANGPTL4), was expressed at very low levels in all bladder cancer cell lines we examined. Previous studies had demonstrated that ANGPTL4 is highly expressed in some cancers, but downregulated, by DNA methylation, in others. Consequently, owing to these seemingly conflicting functions in distinct cancers, the precise role of ANGPTL4 in the etiology of UC remains unclear. In this study, using methylation-specific PCR and bisulfite pyrosequencing, we show that ANGPTL4 is transcriptionally repressed by DNA methylation in UC cell lines and primary tumor samples, as compared with adjacent noncancerous bladder epithelium. Functional studies further demonstrated that ectopic expression of ANGPTL4 potently suppressed UC cell proliferation, monolayer colony formation in vitro, and invasion, migration, and xenograft formation in vivo. Surprisingly, circulating ANGPTL4 was significantly higher in plasma samples from UC patients than normal control, suggesting it might be secreted from other cell types. Interestingly, our data also indicated that exogenous cANGPTL4 could promote cell proliferation and cell migration via activation of signaling through the Erk/focal adhesion kinase axis. We further confirmed that mouse xenograft tumor growth could be promoted by administration of exogenous cANGPTL4. Finally, immunohistochemistry demonstrated that ANGPTL4 was downregulated in tumor cells but overexpressed in tumor adjacent stromal tissues of muscle-invasive UC tissue samples. In conclusion, our data support dual roles for ANGPTL4 in UC progression, either as a tumor suppressor or oncogene, in response to microenvironmental context.

Intravascular Survival and Extravasation of Tumor Cells

Most metastasizing tumor cells reach distant sites by entering the circulatory system. Within the bloodstream, they are exposed to severe stress due to loss of adhesion to extracellular matrix, hemodynamic shear forces, and attacks of the immune system, and only a few cells manage to extravasate and to form metastases. We review the current understanding of the cellular and molecular mechanisms that allow tumor cells to survive in the intravascular environment and that mediate and promote tumor cell extravasation. As these processes are critical for the metastatic spread of tumor cells, we discuss implications for potential therapeutic approaches and future research.

Angiopoietin-like 4 induces a β-catenin-mediated upregulation of ID3 in fibroblasts to reduce scar collagen expression

In adult skin wounds, collagen expression rapidly re-establishes the skin barrier, although the resultant scar is aesthetically and functionally inferior to unwounded tissue. Although TGFβ signaling and fibroblasts are known to be responsible for scar-associated collagen production, there are currently no prophylactic treatments for scar management. Fibroblasts in crosstalk with wound keratinocytes orchestrate collagen expression, although the precise paracrine pathways involved remain poorly understood. Herein, we showed that the matricellular protein, angiopoietin-like 4 (ANGPTL4), accelerated wound closure and reduced collagen expression in diabetic and ANGPTL4-knockout mice. Similar observations were made in wild-type rat wounds. Using human fibroblasts as a preclinical model for mechanistic studies, we systematically elucidated that ANGPTL4 binds to cadherin-11, releasing membrane-bound β-catenin which translocate to the nucleus and transcriptionally upregulate the expression of Inhibitor of DNA-binding/differentiation protein 3 (ID3). ID3 interacts with scleraxis, a basic helix-loop-helix transcription factor, to inhibit scar-associated collagen types 1α2 and 3α1 production by fibroblasts. We also showed ANGPTL4 interaction with cadherin-11 in human scar tissue. Our findings highlight a central role for matricellular proteins such as ANGPTL4 in the attenuation of collagen expression and may have a broader implication for other fibrotic pathologies.

Elevation of adenylate energy charge by angiopoietin-like 4 enhances epithelial-mesenchymal transition by inducing 14-3-3γ expression

Metastatic cancer cells acquire energy-intensive processes including increased invasiveness and chemoresistance. However, how the energy demand is met and the molecular drivers that coordinate an increase in cellular metabolic activity to drive epithelial–mesenchymal transition (EMT), the first step of metastasis, remain unclear. Using different in vitro and in vivo EMT models with clinical patient’s samples, we showed that EMT is an energy-demanding process fueled by glucose metabolism-derived adenosine triphosphate (ATP). We identified angiopoietin-like 4 (ANGPTL4) as a key player that coordinates an increase in cellular energy flux crucial for EMT via an ANGPTL4/14-3-3γ signaling axis. This augmented cellular metabolic activity enhanced metastasis. ANGPTL4 knockdown suppresses an adenylate energy charge elevation, delaying EMT. Using an in vivo dual-inducible EMT model, we found that ANGPTL4 deficiency reduces cancer metastasis to the lung and liver. Unbiased kinase inhibitor screens and Ingenuity Pathway Analysis revealed that ANGPTL4 regulates the expression of 14-3-3γ adaptor protein via the phosphatidylinositol-3-kinase/AKT and mitogen-activated protein kinase signaling pathways that culminate to activation of transcription factors, CREB, cFOS and STAT3. Using a different mode of action, as compared with protein kinases, the ANGPTL4/14-3-3γ signaling axis consolidated cellular bioenergetics and stabilized critical EMT proteins to coordinate energy demand and enhanced EMT competency and metastasis, through interaction with specific phosphorylation signals on target proteins.

ANGPTL4 T266M variant is associated with reduced cancer invasiveness

Angiopoietin-like 4 (ANGPTL4) is a secretory protein that can be cleaved to form an N-terminal and a C-terminal protein. Studies performed thus far have linked ANGPTL4 to several cancer-related and metabolic processes. Notably, several point mutations in the C-terminal ANGPTL4 (cANGPTL4) have been reported, although no studies have been performed that ascribed these mutations to cancer-related and metabolic processes. In this study, we compared the characteristics of tumors with and without wild-type (wt) cANGPTL4 and tumors with cANGPTL4 bearing the T266M mutation (T266M cANGPTL4). We found that T266M cANGPTL4 bound to integrin α5β1 with a reduced affinity compared to wt, leading to weaker activation of downstream signaling molecules. The mutant tumors exhibited impaired proliferation, anoikis resistance, and migratory capability and had reduced adenylate energy charge. Further investigations also revealed that cANGPTL4 regulated the expression of Glut2. These findings may explain the differences in the tumor characteristics and energy metabolism observed with the cANGPTL4 T266M mutation compared to tumors without the mutation.

Gold Nanoparticles Induced Endothelial Leakiness Depends on Particle Size and Endothelial Cell Origin

The endothelium presents a formidable barrier for cancer nanomedicine, as the intravenously introduced nanomedicine needs to leave the blood vessel at the tumor site. Endothelial permeability and retention effect (EPR) is not dependable since it is derived from tumors. Certain nanoparticles with specific characteristics are able to induce micrometer sized gaps between endothelial cells. This effect is called "nanoparticle induced endothelial leakiness" (NanoEL). NanoEL therefore allows the nanotechnology to control access to the tumor even in the absence of any EPR effect. Morever, NanoEL can be applicable to noncancer issues, thereby expanding its usefulness in other subfields of nanomedicine. In this paper, we have shown that Gold (Au) nanoparticles within the range of 10-30 nm are good NanoEL inducing particles. As not all endothelial cells have the same permeability, we found that human mammary endothelial cells and human skin endothelial cells are sensitive to Au induced NanoEL, while human umbilical vein endothelial cells are insensitive, reflective of their innate nature of endothelial permeability. The size window and endothelial cell type sensitivity then helps the nanotechnologists to design future nanoparticles that either exploit NanoEL as a nanotechnology driven strategy to access immature tumors, which do not induce the EPR effect, or avoid NanoEL as a nanotoxic side effect.

Effect of Maxing Shigan Tang on H1N1 Influenza A Virus-Associated Acute Lung Injury in Mice

OBJECTIVE

This study is aimed at examining the effects of Maxing Shigan Tang (MST) treatment on H1N1-associated acute lung injury (ALI) and exploring the possible mechanism.

MATERIAL AND METHODS

Mice were randomly divided into a control group, model group, peroxisomal proliferator activator receptor γ (PPARγ) inhibition group (PPARγ-), PPARγ activation group (PPARγ+), and MST group. Influenza A (H1N1) virus of the Fort Monmouth 1 (FM1) strain was used to induce an ALI mice model. Hematoxylin and eosin staining was performed to investigate the effect of MST treatment on H1N1-associated ALI. Cell apoptosis of lung tissues of each group were conducted through transferase-mediated dUTP nick end-labeling methods. Moreover, the expression level of caspase 3, activity of caspase 3, and serum level of tumor necrosis factor (TNF)-α of each group were also analyzed. Finally, quantitative real-time polymerase chain reaction and Western blotting analysis were carried out to detect angiopoietin-like 4 (ANGPTL4) expression level.

RESULTS

We found that mice infected with the FM1 strain of H1N1 influenza A virus developed severe ALI, and MST could improve H1N1-induced ALI. Moreover, MST decreased lung cell apoptosis and reduced the serum content of TNF-α. In addition, MST significantly induced the ANGPTL4 expression in H1N1-induced ALI.

CONCLUSION

MST improves H1N1-associated ALI maybe through targeting ANGPTL4 in mice.

Angiopoietin-like protein 3 and 4 expression 4 and their serum levels in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the 6th most common cancer and the 3rd leading cause of cancer causing death allover the world. The aim of this research to explore the clinical relevance of blood angiopoietin-like protein-3 (ANGPTL3) and ANGPTL4 expression and their proteins levels as non invasive biomarkers in cirrhotic and HCC patients and their influence on the clinicopathological features of HCC.

MATERIAL AND METHODS

This work comprised 200 patients with chronic hepatitis (120 cases complicated with cirrhosis, 80 patients with primary HCC) and 100 controls. circulating ANGPTL3 and ANGPTL4 expression was estimated by real-time polymerase chain reaction (RT-PCR). ANGPTL3 and ANGPTL4 protein levels were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The circulating ANGPTL3 and ANGPTL 4 expression was significantly elevated in HCC cases compared to chronic hepatitis patients and controls. There were much more serum ANGPTL3 and ANGPTL4 values in HCC and chronic hepatitis patients as compared to controls, but we couldn't detect this significance between chronic hepatitis and HCC cases as regards ANGPTL4. By Multiple stepwise linear regression analysis, an increased ANGPTL3 expression, alpha-fetoprotein (AFP), serum ANGPTL 3 levels, Child-Pugh grade were significantly assosciatedassociated with increased risk of HCC. Logistic regression analysis revealed that ANGPTL 3 expression and AFP levels were the only pridectorspredictors of HCC (odd's ratio (OR)=8.9; 8.6 respectively, P=0.003). Receiver operator characteristic (ROC) demonsterated that serum ANGPTL3 and ANGPTL4 levels were usufuluseful biomarkers discriminating chronic hepatitis cases from controls (AUC=0.820,0.887, respectively P<0.001). However, they fail to discriminate HCC patients from chronic hepatitis patients (P=0.27,0.12 respectively). Moreover, ANGPTL3 and ANGPTL 4 expression were promising biomarkers discriminating chronic hepatitis cases from controls and those HCC cases from chronic hepatitis patients (P<0.001). Combined ANGPTL3 expression and serum level wasn't useful in discriminating HCC patient from chronic hepatitis (P=0.09). In contrast, combined ANGPTL4 expression and serum level was an useful biomarker discriminating HCC cases from chronic hepatitis.

CONCLUSION

ANGPTL3 and ANGPTL 4 expression and serum levels can be promising non invasive biomarkers in diagnosis of chronic hepatitis and HCC especially their expression could be useful in discriminating HCC from chronic hepatitis patients.

Nanoparticle Density: A Critical Biophysical Regulator of Endothelial Permeability

The integrity of the vasculature system is intrinsically sensitive to a short list of biophysical cues spanning from nano to micro scales. We have earlier found that certain nanomaterials could induce endothelial leakiness (nanoparticle induced endothelial leakiness, nanoEL). In this study, we report that the density of the nanomaterial, a basic intrinsic material property not implicated in many nanoparticle-mediated biological effects, predominantly dictates the nanoEL effect. We demonstrated that the impinging force exerted by a library of increasing effective densities but consistently sized silica nanoparticles (SiNPs) could directly increase endothelial permeability. The crossover effective particle density that induced nanoEL was determined to be between 1.57 g/cm³ to 1.72 g/cm³. It was also found that a cumulative gravitational-mediated force of around 1.8 nN/μm along the boundaries of the vascular endothelial cadherin (VE-cad) adherens junctions appeared to be a critical threshold force required to perturb endothelial cell-cell adhesion. The net result is the "snapping" of the mechanically pretensed VE-cad (Nanosnap), leading to the formation of micron-sized gaps that would dramatically increase endothelial leakiness.

Data-Driven Discovery of Extravasation Pathway in Circulating Tumor Cells

Circulating tumor cells (CTCs) play a crucial role in cancer dissemination and provide a promising source of blood-based markers. Understanding the spectrum of transcriptional profiles of CTCs and their corresponding regulatory mechanisms will allow for a more robust analysis of CTC phenotypes. The current challenge in CTC research is the acquisition of useful clinical information from the multitude of high-throughput studies. To gain a deeper understanding of CTC heterogeneity and identify genes, pathways and processes that are consistently affected across tumors, we mined the literature for gene expression profiles in CTCs. Through in silico analysis and the integration of CTC-specific genes, we found highly significant biological mechanisms and regulatory processes acting in CTCs across various cancers, with a particular enrichment of the leukocyte extravasation pathway. This pathway appears to play a pivotal role in the migration of CTCs to distant metastatic sites. We find that CTCs from multiple cancers express both epithelial and mesenchymal markers in varying amounts, which is suggestive of dynamic and hybrid states along the epithelial-mesenchymal transition (EMT) spectrum. Targeting the specific molecular nodes to monitor disease and therapeutic control of CTCs in real time will likely improve the clinical management of cancer progression and metastases.

Determinants of Organotropic Metastasis

The spread of cancer from a primary tumor to distant organ sites is the most devastating aspect of malignancy. Dissemination to specific organs depends upon blood flow patterns and characteristics of the distant organ environment, such as the vascular architecture, stromal cell content, and the biochemical milieu of growth factors, signaling molecules, and metabolic substrates, which can be permissive or antagonistic to metastatic colonization. Metastatic tumor cells possess intrinsic cellular properties selected for adaptation to specific organ environments, where they co-opt growth and survival signals, undergo metabolic reprogramming, and subvert resident stromal cell activities to promote extravasation, immune evasion, angiogenesis, and overt metastatic growth. Recent work and new experimental models of metastatic organotropism are uncovering crucial details of how malignant cells metastasize to specific tissues, revealing key mediators that prepare metastatic niches in specific organs and identifying new targets that offer attractive options for therapeutic intervention.

Potential Role of ANGPTL4 in the Cross Talk between Metabolism and Cancer through PPAR Signaling Pathway

The angiopoietin-like 4 (ANGPTL4) protein belongs to a superfamily of secreted proteins structurally related to factors modulating angiogenesis known as angiopoietins. At first, ANGPTL4 has been identified as an adipokine exclusively involved in lipid metabolism, because of its prevalent expression in liver and adipose tissue. This protein regulates lipid metabolism by inhibiting lipoprotein lipase (LPL) activity and stimulating lipolysis of white adipose tissue (WAT), resulting in increased levels of plasma triglycerides (TG) and fatty acids. Subsequently, ANGPTL4 has been shown to be involved in several nonmetabolic and metabolic conditions, both physiological and pathological, including angiogenesis and vascular permeability, cell differentiation, tumorigenesis, glucose homoeostasis, lipid metabolism, energy homeostasis, wound healing, inflammation, and redox regulation. The transcriptional regulation of ANGPTL4 can be modulated by several transcription factors, including PPARα, PPARβ/δ, PPARγ, and HIF-1α, and nutritional and hormonal conditions. Several studies showed that high levels of ANGPTL4 are associated with poor prognosis in patients with various solid tumors, suggesting an important role in cancer onset and progression, metastasis, and anoikis resistance. Here, we have discussed the potential role of ANGPTL4 in mediating the cross talk between metabolic syndromes, such as diabetes and obesity, and cancer through regulation of its expression by PPARs.

Dynamic interactions of Plasmodium spp. with vascular endothelium

Plasmodial species are protozoan parasites that infect erythrocytes. As such, they are in close contact with microvascular endothelium for most of the life cycle in the mammalian host. The host-parasite interactions of this stage of the infection are responsible for the clinical manifestations of the disease that range from a mild febrile illness to severe and frequently fatal syndromes such as cerebral malaria and multi-organ failure. Plasmodium falciparum, the causative agent of the most severe form of malaria, is particularly predisposed to modulating endothelial function through either direct adhesion to endothelial receptor molecules, or by releasing potent host and parasite products that can stimulate endothelial activation and/or disrupt barrier function. In this review, we provide a critical analysis of the current clinical and laboratory evidence for endothelial dysfunction during severe P. falciparum malaria. Future investigations using state-of-the-art technologies such as mass cytometry and organs-on-chips to further delineate parasite-endothelial cell interactions are also discussed.

Multiple Roles of Angiopoietin-Like 4 in Osteolytic Disease

Hypoxia and the hypoxia-inducible factor (HIF) transcription factor drive pathological bone loss in conditions including rheumatoid arthritis (RA), osteoarthritis, osteoporosis, primary bone tumours, and bone metastatic cancer. There is therefore considerable interest in determining the function(s) of HIF-induced genes in these pathologies. Angiopoietin-like 4 (ANGPTL4) is an adipose-derived, HIF-1α- and PPARγ-induced gene that was originally discovered as an endocrine and autocrine/paracrine regulator of lipid metabolism. Given the inverse relationship between bone adiposity and fracture risk, ANGPTL4 might be considered a good candidate for mediating the downstream effects of HIF-1α relevant to osteolytic disease. This review will consider the possible roles of ANGPTL4 in regulation of osteoclast-mediated bone resorption, cartilage degradation, angiogenesis, and inflammation, focusing on results obtained in the study of RA. Possible roles in other musculoskeletal pathologies will also be discussed. This will highlight ANGPTL4 as a regulator of multiple disease processes, which could represent a novel therapeutic target in osteolytic musculoskeletal disease.

PPARβ/δ in human cancer

The nuclear receptor factor peroxisome proliferator-activated receptor (PPARβ/δ) can regulate its target genes by transcriptional activation or repression through both ligand-dependent and independent mechanism as well as by interactions with other transcription factors. PPARβ/δ exerts essential regulatory functions in intermediary metabolism that have been elucidated in detail, but clearly also plays a role in inflammation, differentiation, apoptosis and other cancer-associated processes, which is, however, mechanistically only partly understood. Consistent with these functions clinical associations link the expression of PPARβ/δ and its target genes to an unfavorable outcome of several human cancers. However, the available data do not yield a clear picture of PPARβ/δ's role in cancer-associated processes and are in fact partly controversial. This article provides an overview of this research area and discusses the role of PPARβ/δ in cancer in light of the complex mechanisms of its transcriptional regulation and its potential as a druggable anti-cancer target.

Oleic acid-induced ANGPTL4 enhances head and neck squamous cell carcinoma anoikis resistance and metastasis via up-regulation of fibronectin

Obese patients have higher levels of free fatty acids (FFAs) in their plasma and a higher risk of cancer than their non-obese counterparts. However, the mechanisms involved in the regulation of cancer metastasis by FFAs remain unclear. In this study, we found that oleic acid (OA) induced angiopoietin-like 4 (ANGPTL4) protein expression and secretion and conferred anoikis resistance to head and neck squamous cell carcinomas (HNSCCs). The autocrine production of OA-induced ANGPTL4 further promoted HNSCC migration and invasion. In addition, the expression of peroxisome proliferator-activated receptor (PPAR) was essential for the OA-induced ANGPTL4 expression and invasion. The levels of OA-induced epithelial-mesenchymal transition markers, such as vimentin, MMP-9, and fibronectin and its downstream effectors Rac1/Cdc42, were significantly reduced in ANGPTL4-depleted cells. Knocking down fibronectin inhibited the expression of MMP-9 and repressed OA- and recombinant ANGPTL4-induced HNSCC invasion. On the other hand, ANGPTL4 siRNA inhibited OA-induced MMP-9 expression, which was reversed in fibronectin-overexpressing cells. Furthermore, the depletion of ANGPTL4 impeded the OA-primed metastatic seeding of tumor cells in the lungs. These results demonstrate that OA enhances HNSCC metastasis through the ANGPTL4/fibronectin/Rac1/Cdc42 and ANGPTL4/fibronectin/MMP-9 signaling axes.

Epidermal growth factor-induced ANGPTL4 enhances anoikis resistance and tumour metastasis in head and neck squamous cell carcinoma

Epidermal growth factor (EGF) is important for cancer cell proliferation, angiogenesis and metastasis in many types of cancer. However, the mechanisms involved in EGF-induced head and neck squamous cell carcinoma (HNSCC) metastasis remain largely unknown. In this study, we reveal that angiopoietin-like 4 (ANGPTL4) plays an important role in the regulation of EGF-induced cancer metastasis. We showed that EGF-induced ANGPTL4 expression promoted anoikis resistance and cancer cell migration and invasion in HNSCC. In addition, depletion of ANGPTL4 inhibited EGF-induced cancer cell invasion. Autocrine production of EGF-induced ANGPTL4 regulated the expression of matrix metalloproteinases (MMPs). The induction of MMP-1 gene expression by ANGPTL4-activated integrin β1 signalling occurred through the AP-1 binding site in the MMP-1 gene promoter. Furthermore, down-regulation of MMP-1 impeded EGF- and recombinant ANGPTL4-enhanced HNSCC cell migration and invasion. Depletion of ANGPTL4 significantly blocked EGF-primed extravasation and metastatic seeding of tumour cells and MMP-1 expression in lungs. However, no effect of ANGPTL4 on tumour growth was observed. These results suggest that EGF-induced expression and autocrine production of ANGPTL4 enhances HNSCC metastasis via the up-regulation of MMP-1 expression. Inhibition of ANGPTL4 expression may be a potential strategy for the treatment of EGFR-mediated HNSCC metastasis.

ANGPTL4-αvβ3 interaction counteracts hypoxia-induced vascular permeability by modulating Src signalling downstream of vascular endothelial growth factor receptor 2

Dynamic control of endothelial cell junctions is essential for vascular homeostasis and angiogenesis. We recently provided genetic evidence that ANGPTL4 is a key regulator of vascular integrity both during developmental and in hypoxia-induced pathological conditions. The purpose of the present study was to decipher the molecular mechanisms through which ANGPTL4 regulates vascular integrity. Using surface plasmon resonance and proximity ligation assays, we show that ANGPTL4 binds integrin αvβ3. In vitro and in vivo functional assays with Angptl4-deficient mice demonstrate that ANGPTL4-αvβ3 interaction is necessary to mediate ANGPTL4 vasoprotective effects. Mechanistically, ANGPTL4-αvβ3 interaction enhances Src recruitment to integrin αvβ3 and inhibits Src signalling downstream of vascular endothelial growth factor receptor 2 (VEFGR2), thereby repressing hypoxia-induced breakdown of VEGFR2-VE-cadherin and VEGFR2-αvβ3 complexes. We further demonstrate that intravitreal injection of recombinant human ANGPTL4 limits vascular permeability and leads to increased adherens junction and tight junction integrity. These findings identify a novel mechanism by which ANGPTL4 counteracts hypoxia-driven vascular permeability through integrin αvβ3 binding, modulation of VEGFR2-Src kinase signalling, and endothelial junction stabilization. We further demonstrate that Angptl4-deficient mice show increased vascular leakage in vivo in a model of laser-induced choroidal neovascularization, indicating that this newly identified ANGPTL4-αvβ3 axis might be a target for pharmaceutical intervention in pathological conditions. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Implications of Hypoxia in Breast Cancer Metastasis to Bone

Most solid tumors contain regions of hypoxia in which increased cell proliferation promotes increased oxygen consumption and the condition is further exacerbated as cancer cells become localized far from a functional blood vessel, further decreasing the oxygen supply. An important mechanism that promotes cell adaptation to hypoxic conditions is the expression of hypoxia-inducible factors (HIFs). Hypoxia-inducible factors transcriptionally regulate many genes involved in the invasion and metastasis of breast cancer cells. Patients, whose primary tumor biopsies show high HIF expression levels, have a greater risk of metastasis. The current review will highlight the potential role of hypoxia in breast cancer metastasis to the bone by considering the regulation of many steps in the metastatic process that include invasion, migration, margination and extravasation, as well as homing signals and regulation of the bone microenvironment.

Enhancement of active MMP release and invasive activity of lymph node metastatic tongue cancer cells by elevated signaling via the TNF-α-TNFR1-NF-κB pathway and a possible involvement of angiopoietin-like 4 in lung metastasis

To study the role of TNF-α in tongue cancer metastasis, we made highly metastatic cells from a human oral squamous cell carcinoma cell line (SAS) by repeating the passage in which the cells were injected into a nude mouse tongue and harvested from metastasized cervical lymph nodes. Cancer cells after 5 passages (GSAS/N5) increased invasive activity 7-fold in a TNF-α receptor 1 (TNFR1)-dependent manner and enhanced mRNA expression of TNF-α and TNFR1. In the highly metastatic cells, NF-κB activation was upregulated via elevated phosphorylation of Akt and Ikkα/β in the signaling pathway and secretion of TNF-α, active MMP-2 and MMP-9 increased. Suppression of increase of TNF-α mRNA expression and MMP secretion by NF-κB inhibitor NBD peptide suggested a positive feedback loop in GSAS/N5 cells; TNF-α activates NF-κB and activated NF-κB induces further TNF-α secretion, leading to increase of active MMP release and promotion of invasion and metastasis of the cells. GSAS/N5 cells that had been injected into the nude mouse tongue and harvested from metastasized lungs multiplied angiopoietin-like 4 (angptl4) expression with enhanced migration activity, which indicated a possible involvement of angptl4 in lung metastasis of the cells. These results suggest that TNF-α and angptl4 promote metastasis of the oral cancer cells, thus, these molecules may be therapeutic targets for patients with tongue cancer.

The downregulation of ANGPTL4 inhibits the migration and proliferation of tongue squamous cell carcinoma

OBJECTIVE

Tongue squamous cell carcinoma (TSCC) is the most common malignant cancer in the oral cavity, with a high rate of metastasis to the neck lymphoid node. Angiopoietin-like protein 4 (ANGPTL4) and microvessel density (MVD) may be novel indicators for tumor metastasis. The aim of the present study was to investigate the expression and function of ANGPTL4 in TSCC and the relationship between ANGPTL4 and MVD.

METHODS

The expression levels of ANGPTL4 and MVD (CD34) were analyzed in 65 TSCC specimens and the adjacent non-cancerous tissues using immunohistochemistry (IHC). siRNA was delivered into TSCCA cells to downregulate ANGPTL4 expression. Subsequently, validation with real-time RT-PCR and western blot analyses was performed to analyze ANGPTL4 expression levels. In addition, a proliferation assay, migration and invasion assays were carried out.

RESULTS

ANGPTL4 expression was associated with tumor stage, lymph node metastasis and MVD expression. Cox regression analysis showed that high levels of ANGPTL4 expression were closely associated with poor survival time. In vitro analyses using qRT-PCR and western blot confirmed that ANGPTL4 was successfully inhibited in TSCCA cells. Suppressing ANGPTL4 resulted in the inhibition of cell proliferation and migration, but neither invasion nor cisplatin resistance was significantly affected.

CONCLUSION

High expression levels of ANGPTL4 are associated with the T stage, lymphatic metastasis, angiogenesis and poor overall survival in TSCC patients. The downregulation of ANGPTL4 inhibits the migration and proliferation of cells in TSCC. Taken together, ANGPTL4 may serve as a novel biomarker and therapeutic target for TSCC.

Angiopoietin-like 4 promotes angiogenesis in the tendon and is increased in cyclically loaded tendon fibroblasts

KEY POINTS

Angiopoietin-like 4 (ANGPTL4) modulates tendon neovascularization. Cyclic loading stimulates the activity of transforming growth factor-β and hypoxia-inducible factor 1α and thereby increases the expression and release of ANGPTL4 from human tendon cells. Targeting ANGPTL4 and its regulatory pathways is a potential avenue for regulating tendon vascularization to improve tendon healing or adaptation.

ABSTRACT

The mechanisms that regulate angiogenic activity in injured or mechanically loaded tendons are poorly understood. The present study examined the potential role of angiopoietin-like 4 (ANGPTL4) in the angiogenic response of tendons subjected to repetitive mechanical loading or injury. Cyclic stretching of human tendon fibroblasts stimulated the expression and release of ANGPTL4 protein via transforming growth factor-β (TGF-β) and hypoxia-inducible factor 1α (HIF-1α) signalling, and the released ANGPTL4 was pro-angiogenic. Angiogenic activity was increased following ANGPTL4 injection into mouse patellar tendons, whereas the patellar tendons of ANGPTL4 knockout mice displayed reduced angiogenesis following injury. In human rotator cuff tendons, the expression of ANGPTL4 was correlated with the density of tendon endothelial cells. To our knowledge, this is the first study characterizing a role of ANGPTL4 in the tendon. ANGPTL4 may assist in the regulation of vascularity in the injured or mechanically loaded tendon. TGF-β and HIF-1α comprise two signalling pathways that modulate the expression of ANGPTL4 by mechanically stimulated tendon fibroblasts and, in the future, these could be manipulated to influence tendon healing or adaptation.

Endothelial Rac1 is essential for hematogenous metastasis to the lung

A variety of vasoactive stimuli induce endothelial permeability through Rac1, a membrane of Rho small GTPases. Here, we determine whether tumor-secreted vasoactive stimulant through Rac1 inducing permeability contributes to hematogenous metastasis. Activation of Rac1 was assayed in human umbilical vein endothelial cells (HUVEC), transendothelial passages were measured by Transwell chambers, and hematogenously metastatic mouse model was generated by intravenous injection with Lewis lung carcinoma cells (LLC). LLC secreted abundant vascular endothelial growth factor (VEGF) in the culture media and sera of mice bearing LLC xenografts or metastatic LLC, and VEGF activated Rac1 through VEGF receptors/PI3Kβ signaling cascade, resulting in hyperoxidative stress and consequent hyperpermeability in HUVEC. Moreover, in co-culture of LLC and HUVEC, significant increases in endothelial permeability and transendothelial migration of LLC were robustly attenuated by either anti-VEGF neutralizing antibody or Rac1 knockdown in HUVEC. Finally, in metastatic mouse model, deletion of one copy of Rac1 in endothelium not only significantly attenuated LLC-induced vascular permeability, but robustly reduced the metastasis of LLC to lungs. This study supports that tumor-secreted vasoactive stimuli activate Rac1 to induce permeability and consequent transendothelial migration of tumor cells, and that loss of Rac1 function in endothelium is an effective therapeutic intervention for hematogenous metastasis.

Tumor cell intravasation

The process of entering the bloodstream, intravasation, is a necessary step in the development of distant metastases. The focus of this review is on the pathways and molecules that have been identified as being important based on current in vitro and in vivo assays for intravasation. Properties of the vasculature which are important for intravasation include microvessel density and also diameter of the vasculature, with increased intravasation correlating with increased vessel diameter in some tumors. TGFB signaling can enhance intravasation at least in part through induction of EMT, and we discuss other TGFB target genes that are important for intravasation. In addition to TGFB signaling, a number of studies have demonstrated that activation of EGF receptor family members stimulates intravasation, with downstream signaling through PI3K, N-WASP, RhoA, and WASP to induce invadopodia. With respect to proteases, there is strong evidence for contributions by uPA/uPAR, while the roles of MMPs in intravasation may be more tumor specific. Other cells including macrophages, fibroblasts, neutrophils, and platelets can also play a role in enhancing tumor cell intravasation. The technology is now available to interrogate the expression patterns of circulating tumor cells, which will provide an important reality check for the model systems being used. With a better understanding of the mechanisms underlying intravasation, the goal is to provide new opportunities for improving prognosis as well as potentially developing new treatments.

Biomedical applications of nano-titania in theranostics and photodynamic therapy

Titanium dioxide (TiO₂) is one of the most abundantly used nanomaterials for human life. It is used in sunscreen, photovoltaic devices, biomedical applications and as a food additive and environmental scavenger.

Hypoxia-inducible factor 1 and breast cancer metastasis

Accumulating evidence has shown that the hypoxic microenvironment, which is critical during cancer development, plays a key role in regulating breast cancer progression and metastasis. The effects of hypoxia-inducible factor 1 (HIF-1), a master regulator of the hypoxic response, have been extensively studied during these processes. In this review, we focus on the roles of HIF-1 in regulating breast cancer cell metastasis, specifically its effects on multiple key steps of metastasis, such as epithelial-mesenchymal transition (EMT), invasion, extravasation, and metastatic niche formation. We also discuss the roles of HIF-1-regulated non-coding RNAs in breast cancer metastasis, and therapeutic opportunities for breast cancer through targeting the HIF-1 pathway.

Establishment of monoclonal HCC cell lines with organ site-specific tropisms

Background

Organ site-specific metastasis is an ominous feature for most poor-prognostic hepatocellular carcinoma (HCC) patients. Cancer cell lines and animal models are indispensable for investigating the molecular mechanisms of organ specific tropism. However, till now, little is known about the drivers in HCC metastatic tropism, and also no effective way has been developed to block the process of tropistic metastasis.

Methods

In this study, we established several monoclonal HCC cell lines from HCCLM3-RFP together with their xenograft models, and then analyzed their metastatic potentials and tropisms using in-vitro and in-vivo assays, and finally elucidated the driving forces of HCC tropistic metastases.

Results

Six monoclonal cell lines with different organ site-specific tropism were established successfully. SPARC, VCAM1 and ANGPTL4 were found positively correlated with the potentials of lung metastasis, while ITGA1 had a positive relation to lymph node metastasis of enterocoelia.

Conclusions

By our powerful platforms, HCC metastatic tropisms in clinic could be easily mimicked and recapitulated for exploring the bilateral interactions between tumor and its microenvironment, elucidating the drivers of HCC metastatic tropisms, and testing anti-cancer effects of newly developed agent in pre-clinical stage.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1692-0) contains supplementary material, which is available to authorized users.

Surviving at a Distance: Organ-Specific Metastasis

The clinical manifestation of metastasis in a vital organ is the final stage of cancer progression and the main culprit of cancer-related mortality. Once established, metastasis is devastating, but only a small proportion of the cancer cells that leave a tumor succeed at infiltrating, surviving, and ultimately overtaking a distant organ. The bottlenecks that challenge cancer cells in newly invaded microenvironments are organ-specific and consequently demand distinct mechanisms for metastatic colonization. We review the metastatic traits that allow cancer cells to colonize distinct organ sites.

Influenza lung injury: mechanisms and therapeutic opportunities

In this Perspectives, we discuss some recent developments in the pathogenesis of acute lung injury following influenza infection, with an emphasis on promising therapeutic leads. Damage to the alveolar-capillary barrier has been quantified in mice, and agents have been identified that can help to preserve barrier integrity, such as vasculotide, angiopoietin-like 4 neutralization, and sphingosine 1-phosphate mimics. Results from studies using mesenchymal stem cells have been disappointing, despite promising data in other types of lung injury. The roles of fatty acid binding protein 5, prostaglandin E2, and the interplay between IFN-γ and STAT1 in epithelial signaling during infection have been addressed in vitro. Finally, we discuss the role of autophagy in inflammatory cytokine production and the viral life cycle and the opportunities this presents for intervention.

Angiopoietin-like 4: A double-edged sword in atherosclerosis and ischemic stroke?

Ischemic stroke is one of the leading causes of death in the world, and thus is a major public health concern. Atherosclerosis, also known as atherogenesis, is a crucial risk factor for cerebral ischemia, yet how it develops remains largely unknown. It has been found, however, that angiopoietin-like protein 4 (ANGPTL4), a protein expressed in vascular endothelial cells, plays a role in the pathophysiology of atherosclerosis and may therefore be involved in ischemic stroke. ANGPTL4 activity is associated with endothelial cell integrity, inflammation, oxidative stress, and lipid metabolism. ANGPTL4 also serves as a potent inhibitor of the lipoprotein lipase, and may inhibit atherogenesis via regulating inflammatory signaling and lipid metabolism. In addition, ANGPTL4 plays a role in the regulation of oxidative stress. However, there currently exists a controversy on the role of ANGPTL4 in endothelial cells. Some studies indicate that ANGPTL4 can protect the integrity of endothelial cells, while others have shown that it can be destructive to the endothelium, thereby leading to the initiation of atherosclerosis. Thus, the effects of ANGPTL4 on development of atherosclerosis and thereby ischemic stroke, are undefined. Further research is needed to better understand ANGPTL4-mediated signaling pathways in endothelial function and to determine its potentials as therapeutic target for atherosclerosis and ischemic stroke.

Advanced glycation end products upregulate angiopoietin-like protein 4 expression by activating the renin-angiotensin system in endothelial cells

The aim of the present study was to investigate the effects of advanced glycation end products (AGEs) on the expression of angiopoietin-like protein 4 (ANGPTL4) and the mechanisms of the effects in endothelial cells. Endothelial cells were incubated with various concentrations of AGEs for 24 h and the expression of ANGPTL4 was detected by quantitative polymerase chain reaction and western blot analysis. The concentration of angiotensin II (Ang II) in conditioned media and cell lysates was measured by enzyme-linked immunosorbent assays. Fluorescein isothiocyanate-labeled dextran filtration assays and transendothelial electrical resistance were performed to evaluate endothelial permeability. AGEs (80 µg/ml) increased the expression of ANGPTL4 and the levels of Ang II (P<0.05). Incubation with AGEs also resulted in a significant increase in endothelial permeability (P<0.05). However, pretreatment with the Ang II receptor blocker losartan (10^-5 M) reduced the effects of AGEs (P<0.05). AGEs upregulated the expression of ANGPTL4 by activating a local renin-angiotensin system in endothelial cells. This may be a new mechanism by which AGEs increase endothelial permeability.

Tumour-derived SPARC drives vascular permeability and extravasation through endothelial VCAM1 signalling to promote metastasis

Disruption of the endothelial barrier by tumour-derived secreted factors is a critical step in cancer cell extravasation and metastasis. Here, by comparative proteomic analysis of melanoma secretomes, we identify the matricellular protein SPARC as a novel tumour-derived vascular permeability factor. SPARC deficiency abrogates tumour-initiated permeability of lung capillaries and prevents extravasation, whereas SPARC overexpression enhances vascular leakiness, extravasation and lung metastasis. SPARC-induced paracellular permeability is dependent on the endothelial VCAM1 receptor and p38 MAPK signalling. Blocking VCAM1 impedes melanoma-induced endothelial permeability and extravasation. The clinical relevance of our findings is highlighted by high levels of SPARC detected in tumour from human pulmonary melanoma lesions. Our study establishes tumour-produced SPARC and VCAM1 as regulators of cancer extravasation, revealing a novel targetable interaction for prevention of metastasis.

Aqueous Levels of Angiopoietin-like 4 and Semaphorin 3E Correlate with Nonperfusion Area and Macular Volume in Diabetic Retinopathy

OBJECTIVE

To investigate the aqueous levels of angiopoietin-like 4 (ANGPTL4), semaphorin 3E (Sema3E), and vascular endothelial growth factor (VEGF) in patients with diabetic retinopathy and to ascertain their association with diabetic retinopathy phenotypes.

DESIGN

Prospective, nonrandomized, comparative case series.

PARTICIPANTS

Of all 104 consecutive patients (104 eyes) who had intravitreal anti-VEGF injections from April 2012 through April 2013 for diabetic macular edema (DME), 51 had severe nonproliferative diabetic retinopathy (NPDR) and 53 had proliferative diabetic retinopathy (PDR). The controls were 54 consecutive nondiabetic patients who had undergone cataract surgery (54 eyes) during the same period.

METHODS

The ANGPTL4, Sema3E, and VEGF levels in aqueous humor samples obtained before intravitreal injections were measured by enzyme-linked immunosorbent assay. Capillary nonperfusion area (NPA) was calculated from encircled angiography using the 7 standard field images described in the Early Treatment Diabetic Retinopathy Study protocol. Total macular volume (TMV) was measured by spectral-domain optical coherence tomography.

MAIN OUTCOME MEASURES

Aqueous ANGPTL4, Sema3E, and VEGF levels in severe NPDR, PDR, and control groups and their correlations with each other, NPA, and TMV.

RESULTS

The severe NPDR and PDR groups had higher aqueous levels of ANGPTL4 and VEGF than the control group (all P < 0.001). The PDR group had higher ANGPTL4 and VEGF levels than the severe NPDR group (both P < 0.001). The aqueous ANGPTL4 levels of all diabetic retinopathy patients correlated positively with NPA (r = 0.820, P = 0.003) and TMV (r = 0.824, P < 0.001). The control group had higher aqueous Sema3E levels than the NPDR and PDR groups (both P < 0.001). Aqueous Sema3E levels correlated negatively with VEGF levels in all subjects (r = -0.57, P = 0.025).

CONCLUSIONS

The ANGPTL4 may be a candidate target in DME treatment and a biomarker of ischemic-induced retinopathy, including diabetic retinopathy.

Angiopoietin-like 4 Increases Pulmonary Tissue Leakiness and Damage during Influenza Pneumonia

Excessive host inflammatory responses negatively impact disease outcomes in respiratory infection. Host-pathogen interactions during the infective phase of influenza are well studied, but little is known about the host's response during the repair stage. Here, we show that influenza infection stimulated the expression of angiopoietin-like 4 (ANGPTL4) via a direct IL6-STAT3-mediated mechanism. ANGPTL4 enhanced pulmonary tissue leakiness and exacerbated inflammation-induced lung damage. Treatment of infected mice with neutralizing anti-ANGPTL4 antibodies significantly accelerated lung recovery and improved lung tissue integrity. ANGPTL4-deficient mice also showed reduced lung damage and recovered faster from influenza infection when compared to their wild-type counterparts. Retrospective examination of human lung biopsy specimens from infection-induced pneumonia with tissue damage showed elevated expression of ANGPTL4 when compared to normal lung samples. These observations underscore the important role that ANGPTL4 plays in lung infection and damage and may facilitate future therapeutic strategies for the treatment of influenza pneumonia.

Systematic analysis of gene expression pattern in has-miR-760 overexpressed resistance of the MCF-7 human breast cancer cell to doxorubicin

BACKGROUND/AIMS

Chemoresistance of breast cancer is a growing problem and still a major clinical obstacle to successful treatment in clinical patients. miR-760 was significantly downregulated in chemoresistance breast cancer tissues compared to chemo-sensitive tissues in our previous study. However, the role of miR-760 in modulating drug resistance remains largely unexplored. In this study, we sought to determine the expression pattern of miR-760 targeted mRNAs, and explore their potential functions and participated-pathways in breast cancer drug resistance cells.

RESULTS

Compared to parental cell line MCF-7, miR-760 was downregulated by 6.15 folds in MCF-7/Adr cells. The qRT-PCR result showed that compared to miR-760 negative control cells group, miR-760 was up-regulated 15.817 folds after miR-760 lentiviral transfection in miR-760 mimics group. The microarray data showed that 270 genes were dysregulated over 2-fold change in MCF-7/Adr cells after miR-760 overexpressed, including 241 up-regulated and 29 downregulated genes. GO analysis result appeared that the predicted target genes of miR-760 mainly regulated DNA binding, protein binding, molecular function, nucleic acid binding, and so on; the pathway analysis data demonstrated that these target genes mainly involved in cell cycle, TGF-beta signaling pathway, mRNA processing reactome, G protein signaling, apoptosis, Wnt signaling pathway, and other signaling pathways. There were 3 predicted target genes (RHOB, ANGOTL4, ABCA1) of miR-760 were selected at a P value<0.05 and the fold enrichment was>40.

CONCLUSION

Our study explored the genes expression pattern after miR-760 overexpresssed, and confirmed 3 dominantly dysregulated genes, which could expand the insights into the miR-760 function and molecular mechanisms in drug resistance of breast cancer. This study might afford a comprehensive understanding of miR-760 as prognostic biomarkers during clinical treatment, and we supposed that the miR-760 expression levels in drug resistance carcinoma tissues could be pursued to develop new strategies for targeted therapies in chemoresistant breast cancer patients.