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Polydatin, a natural derivative of resveratrol, has shown many anticancer properties. However, the underlying mechanisms of its anticancer properties including its effect on the epigenetic landscape are not well understood. Here, we explored the effect of polydatin on histone deacetylase 1 (HDAC1) activity. We used in silico approaches to assess the possible binding of polydatin to the active site pockets of HDAC1 and in vitro approaches to test the potential effects of the interaction on its enzymatic activity. As compared to SAHA, an approved drug, the polydatin showed stronger and stable binding to the HDAC1. The binding energy, conformational changes, formation of extra hydrogen bonding, and other interactions within and outside the active site all favour largely stable and strong polydatin binding to the enzyme. Further, the ADME and toxicity prediction values are encouraging for the evaluation of polydatin as a drug. The laboratory leg of the study substantiated that the polydatin binding was strong and stable enough to inhibit HDAC1 activity in UMS-CC-22B cells as demonstrated by an increase in H3K9 acetylation. In addition, polydatin treated cells showed attenuated proliferation. The in vitro tube formation and migration by HUVEC and UM-SCC-22B cells were inhibited by polydatin. The decreased tube formation due to HDAC1 inhibition is possibly due to up-regulation of the anti-angiogenic gene - TSP1 in UM-SCC-22B cells. As compared to SAHA, more promising results were shown both in its computational calculations and on the cell physiology features. Stronger and stable binding, more anti-proliferative and anti-angiogenic potential were observed with respect to polydatin. Further, the cell death was more pronounced with SAHA treatment. Therefore, polydatin might be a better anticancer drug and can have a potential to replace SAHA in combinational therapeutic regimen. [ABSTRACT FROM AUTHOR]

Polycystic ovary syndrome (PCOS) is a common gynecological endocrine disease with a certain degree of chronic inflammation and abnormal ovarian angiogenesis in reproductive women. Mesenchymal stem cells (MSCs) have potent immunomodulatory properties to regulate ovarian function, while thrombospondin 1 (TSP1) improves the abnormal formation of ovarian vessels. The present study investigated the efficacy of the combined use of adipose‐derived mesenchymal stem cells (ADSCs) and TSP1 in PCOS mice. The PCOS model is established using dehydroepiandrosterone (DHEA) by subcutaneous injection. Ovarian apoptosis is assessed using terminal deoxynucleotidyl transferase dUTP nick‐end labeling (TUNEL). Real‐time quantitative PCR (RT‐PCR) and western blotting are used to detect the expression of inflammatory factors and the levels of angiogenesis‐related factors in ovarian tissues. Inflammatory cells count and ovarian angiogenesis are evaluated by immunofluorescence staining. This research shows that TSP1 and ADSCs treatment can significantly reduce the inflammatory state of PCOS mice, relieve the degree of ovarian cell apoptosis, optimize the ovarian histological manifestations, and restore the levels of related hormones. The proportion of CD31‐positive cells in PCOS mice returned to near‐normal levels. The synergistic use of ADSCs and TSP1 therapy can exert a more impressive effect by inhibiting the ovarian inflammatory response and regulating the balance of angiogenesis than the single application in PCOS mice. [ABSTRACT FROM AUTHOR]

Cluster of differentiation 47 (CD47) occupies the outer membrane of human cells, where it binds to soluble and cell surface receptors on the same and other cells, sculpting their topography and resulting in a pleiotropic receptor‐multiligand interaction network. It is a focus of drug development to temper and accentuate CD47‐driven immune cell liaisons, although consideration of on‐target CD47 effects remain neglected. And yet, a late clinical trial of a CD47‐blocking antibody was discontinued, existent trials were restrained, and development of CD47‐targeting agents halted by some pharmaceutical companies. At this point, if CD47 can be exploited for clinical advantage remains to be determined. Herein an airing is made of the seemingly conflicting actions of CD47 that reflect its position as a junction connecting receptors and signalling pathways that impact numerous human cell types. Prospects of CD47 boosting and blocking are considered along with potential therapeutic implications for autoimmune diseases and cancer. [ABSTRACT FROM AUTHOR]

Background: Natural killer (NK) cells play an important first-line role against tumour and viral infections and are regulated by inhibitory receptor expression. Among these inhibitory receptors, the expression, function, and mechanism of cluster of differentiation 47 (CD47) on NK cells during human immunodeficiency virus (HIV) infection remain unclear. Methods: Fresh peripheral blood mononuclear cells (PBMCs) were collected from people living with HIV (PLWH) and HIV negative controls (NC) subjects. Soluble ligand expression levels of CD47 were measured using ELISA. HIV viral proteins or Toll-like receptor 7/8 (TLR7/8) agonist was used to investigate the mechanisms underlying the upregulation of CD47 expression. The effect of CD47 on NK cell activation, proliferation, and function were evaluated by flow cytometry. RNA-seq was used to identify downstream pathways for CD47 and its ligand interactions. A small molecule inhibitor was used to restore the inhibition of NK cell function by CD47 signalling. Results: CD47 expression was highly upregulated on the NK cells from PLWH, which could be due to activation of the Toll-like receptor 7/8 (TLR7/8) pathway. Compared with NC subjects, PLWH subjects exhibited elevated levels of CD47 ligands, thrombospondin-1 (TSP1), and counter ligand signal regulatory protein-α (SIRPα). The TSP1–CD47 axis drives the suppression of interferon gamma (IFN-γ) production and the activation of the Janus kinase signal transducer and activator of transcription (JAK–STAT) pathway in NK cells. After treatment with a STAT3 inhibitor, the NK cells from PLWH showed significantly improved IFN-γ production. Conclusions: The current data indicate that the binding of the inhibitory receptor CD47 to plasma TSP1 suppresses NK cell IFN-γ production by activating the JAK/STAT3 pathway during HIV infection. Our results suggest that CD47 and its related signalling pathways could be targets for improving NK cell function in people living with HIV. [ABSTRACT FROM AUTHOR]

Astrocytes release numerous factors known to contribute to the process of synaptogenesis, yet knowledge about the signals that control their release is limited. We hypothesized that neuron-derived signals stimulate astrocytes, which respond to neurons through the modulation of astrocyte-released synaptogenic factors. Here we investigate the effect of cholinergic stimulation of astrocytes on synaptogenesis in co-cultured neurons. Using a culture system where primary rat astrocytes and primary rat neurons are first grown separately allowed us to independently manipulate astrocyte cholinergic signaling. Subsequent co-culture of pre-stimulated astrocytes with naïve neurons enabled us to assess how prior stimulation of astrocyte acetylcholine receptors uniquely modulates neuronal synapse formation. Pre-treatment of astrocytes with the acetylcholine receptor agonist carbachol increased the expression of synaptic proteins, the number of pre- and postsynaptic puncta, and the number of functional synapses in hippocampal neurons after 24 h in co-culture. Astrocyte secretion of the synaptogenic protein thrombospondin-1 increased after cholinergic stimulation and inhibition of the receptor for thrombospondins prevented the increase in neuronal synaptic structures. Thus, we identified a novel mechanism of neuron-astrocyte-neuron communication, where neuronal release of acetylcholine stimulates astrocytes to release synaptogenic proteins leading to increased synaptogenesis in neurons. This study provides new insights into the role of neurotransmitter receptors in developing astrocytes and into our understanding of the modulation of astrocyte-induced synaptogenesis. [ABSTRACT FROM AUTHOR]

Secretory and membrane proteins are vital for cell activities, including intra- and intercellular communication. Therefore, protein quality control in the endoplasmic reticulum (ER) is an essential and crucial process for eukaryotic cells. Endoplasmic reticulum-associated degradation (ERAD) targets misfolded proteins during the protein maturation process in the ER and leads to their disposal. This process maintains the ER productive function and prevents misfolded protein stress (i.e., ER stress). The ERAD-stimulating factor ER degradation-enhancing α mannosidase-like 1 protein (EDEM1) acts on misfolded proteins to accelerate ERAD, thereby maintaining the productivity of the ER. However, the detail mechanism underlying the function of EDEM1 in ERAD is not completely understood due to a lack of established physiological substrate proteins. In this study, we attempted to identify substrate proteins for EDEM1 using siRNA. The matrix component thrombospondin-1 (TSP1) and epidermal growth factor receptor (EGFR) were identified as candidate targets of EDEM1. Their protein maturation status and cellular localization were markedly affected by knockdown of EDEM1. We also showed that EDEM1 physically associates with EGFR and enhances EGFR degradation via ERAD. Our data highlight the physiological role of EDEM1 in maintaining specific target proteins and provide a potential approach to the regulation of expression of clinically important proteins. [ABSTRACT FROM AUTHOR]

Objective and design: An accumulating body of evidence has shown that gut microbiota is involved in regulating inflammation; however, it remains undetermined if and how gut microbiota plays an important role in modulating deep venous thrombosis (DVT), which is an inflammation-involved thrombotic event. Subjects: Mice under different treatments were used in this study. Methods and treatment: We induced stenosis DVT in mice by partially ligating the inferior vena cava. Mice were treated with antibiotics, prebiotics, probiotics, or inflammatory reagents to modulate inflammatory states, and their effects on the levels of circulating LPS and DVT were examined. Results: Antibiotic-treated mice or germ-free mice exhibited compromised DVT. Treatment of mice with either prebiotics or probiotics effectively suppressed DVT, which was accompanied with the downregulation of circulating LPS. Restoration of circulating LPS in these mice with a low dose of LPS was able to restore DVT. LPS-induced DVT was blocked by a TLR4 antagonist. By performing proteomic analysis, we identified TSP1 as one of the downstream effectors of circulating LPS in DVT. Conclusion: These results suggest that gut microbiota may play a nonnegligible role in modulating DVT by leveraging the levels of LPS in circulation, thus shedding light on the development of gut microbiota-based strategies for preventing and treating DVT. [ABSTRACT FROM AUTHOR]

Endothelial cells (ECs) serve as a barrier with forming a monolayer lining in the surface of vascular system. Many mature cell types are post-mitotic like neurons, but ECs have the ability to grow during angiogenesis. Vascular endothelial growth factor (VEGF) stimulates growth of vascular ECs derived from arteries, veins, and lymphatics and induces angiogenesis. Senescence of ECs is regarded as a key contributor in aging-induced vascular dysfunction via evoking increase of ECs permeability, impairment of angiogenesis and vascular repair. Several genomics and proteomics studies on ECs senescence reported changes in gene and protein expression that directly correlate with vascular systemic disorder. CD47 functions as a signaling receptor for secreted matricellular protein thrombospondin-1 (TSP1) and plays an important role in several fundamental cellular functions, including proliferation, apoptosis, inflammation, and atherosclerotic response. TSP1-CD47 signaling is upregulated with age in ECs, concurrent with suppression of key self-renewal genes. Recent studies indicate that CD47 is involved in regulation of senescence, self-renewal and inflammation. In this review, we highlight the functions of CD47 in senescent ECs, including modulation of cell cycle, mediation of inflammation and metabolism by the experimental studies, which may provide CD47 as a potential therapeutic target for aging-associated vascular dysfunction. [ABSTRACT FROM AUTHOR]

Background: Persistent pulmonary hypertension remains a major cause of mortality and morbidity in congenital diaphragmatic hernia (CDH). The secreted glycoprotein thrombospondin‐1 (TSP1), a ligand for receptor CD47, is widely expressed on both systemic and pulmonary vascular cells. TSP1‐CD47 signaling has been reported to be one of the pathogeneses of pulmonary hypertension (PH). Methods: After creating a nitrofen‐induced CDH rat model, fetuses were sacrificed on D17, D19 and D21 and divided into a control group and a CDH group. Quantitative real‐time polymerase chain reaction was performed to determine the pulmonary gene expression of TSP1, CD47 and Runx3 (a regulator of TSP1). An immunofluorescence study was performed to evaluate the expression and localization of TSP1, CD47 and Runx3. Results: The relative mRNA expression of pulmonary TSP1, CD47 and Runx3 on D21 was significantly increased in the CDH group (p = 0.005, p = 0.001, p = 0.046, and p = 0.002, respectively). The immunofluorescence study also confirmed the overexpression of TSP1, CD47 and Runx3 in the CDH group. Conclusion: Our results provide evidence that TSP1‐CD47 signaling is involved in the pathogenesis of PH in a nitrofen‐induced CDH model. Our data suggest that anti‐CD47 antibodies can be novel therapeutic targets for the treatment of PH in CDH. [ABSTRACT FROM AUTHOR]

Keloids are benign fibroproliferative diseases with abnormally proliferated bulges beyond the edge of the skin lesions, and they are characterized by uncontrolled fibroblast proliferation and excessive extracellular matrix deposition in the dermis. However, the definite mechanisms that increase fibroblast proliferation and collagen deposition in keloids remain unclear. Thrombospondin 1 (TSP1) has been suggested to play an important role in wound healing and fibrotic disorders, but its role in keloids is unknown. In this study, we aimed to clarify the specific role of TSP1 in keloids and explore the potential mechanism. Our results demonstrated that TSP1 was highly expressed in keloid lesions compared to normal skin. Knockdown of TSP1 in keloid fibroblasts decreased cell proliferation and collagen I deposition. Exogenous TSP1 treatment increased cell proliferation and collagen I deposition in normal fibroblasts. We further investigated the underlying mechanism and found that TSP1 promoted fibroblast proliferation and extracellular matrix deposition by upregulating the IL6/JAK2/STAT3 pathway. Moreover, we verified that TSP1 expression was positively correlated with IL6/STAT3 signalling activity in keloids. Taken together, our findings indicate that TSP1 promotes keloid development via the IL6/JAK2/STAT3 signalling pathway and blocking TSP1 may represent a potential strategy for keloid therapy. [ABSTRACT FROM AUTHOR]

Background: Radiation-induced bystander effect (RIBE) can promote tumor metastasis contributing to the failure of radiotherapy for esophageal squamous cell carcinoma (ESCC). Aberrant expression of DJ-1 has been identified in ESCC; however, the relationship between DJ-1 and RIBE in ESCC remains unknown. Methods: We detected DJ-1 in the serum and cell supernatants by enzyme-linked immunosorbent assay (ELISA) and evaluated tumor metastasis by phenotypic experiments in vivo and in vitro. RNA-seq, mass spectrometry, western blot (WB), immunoprecipitation (IP), and dual-luciferase reporter assays were performed to explore the underlying mechanisms. Results: DJ-1 was highly expressed in the serum of patients with ESCC receiving radiotherapy and was significantly overexpressed in the medium of ESCC cells receiving irradiation. DJ-1 promoted tumor metastasis via the TGF-β1 pathway. Mechanistic studies revealed that DJ-1 bound to HSC70 to promote Smad3 phosphorylation and nuclear aggregation in a protein-interaction manner, which activated the transcription of Thrombospondin-1 (TSP1). Subsequently, the activation of TGF-β1 by TSP1 re-promoted Smad3 phosphorylation and nuclear aggregation, constituting a positive feedback loop to strengthen the metastasis of ESCC cells, which was effectively blocked by LY2109761 and LSKL. Moreover, higher levels of serum DJ-1 in patients with ESCC were related to a poorer prognosis of radiotherapy. Conclusions: Irradiation can induce ESCC cells secreting DJ-1. Secreted DJ-1 enters bystander cells to initiate activation of the TGF-β1 pathway via the DJ-1/HSC70/Smad3 signaling axis. The TSP1/TGF-β1/Smad3 positive feedback pathway constitutes the core pathway that promotes ESCC metastasis. DJ-1 is a useful biomarker for predicting the efficacy of radiotherapy and a potential therapeutic target for reversing RIBE in ESCC. Schematic diagram showing the underlying mechanism that irradiation-induced secretion of DJ-1 accelerates the metastasis of bystander ESCC cells. [ABSTRACT FROM AUTHOR]

Background: Radiation-induced bystander effect (RIBE) can promote tumor metastasis contributing to the failure of radiotherapy for esophageal squamous cell carcinoma (ESCC). Aberrant expression of DJ-1 has been identified in ESCC; however, the relationship between DJ-1 and RIBE in ESCC remains unknown. Methods: We detected DJ-1 in the serum and cell supernatants by enzyme-linked immunosorbent assay (ELISA) and evaluated tumor metastasis by phenotypic experiments in vivo and in vitro. RNA-seq, mass spectrometry, western blot (WB), immunoprecipitation (IP), and dual-luciferase reporter assays were performed to explore the underlying mechanisms. Results: DJ-1 was highly expressed in the serum of patients with ESCC receiving radiotherapy and was significantly overexpressed in the medium of ESCC cells receiving irradiation. DJ-1 promoted tumor metastasis via the TGF-β1 pathway. Mechanistic studies revealed that DJ-1 bound to HSC70 to promote Smad3 phosphorylation and nuclear aggregation in a protein-interaction manner, which activated the transcription of Thrombospondin-1 (TSP1). Subsequently, the activation of TGF-β1 by TSP1 re-promoted Smad3 phosphorylation and nuclear aggregation, constituting a positive feedback loop to strengthen the metastasis of ESCC cells, which was effectively blocked by LY2109761 and LSKL. Moreover, higher levels of serum DJ-1 in patients with ESCC were related to a poorer prognosis of radiotherapy. Conclusions: Irradiation can induce ESCC cells secreting DJ-1. Secreted DJ-1 enters bystander cells to initiate activation of the TGF-β1 pathway via the DJ-1/HSC70/Smad3 signaling axis. The TSP1/TGF-β1/Smad3 positive feedback pathway constitutes the core pathway that promotes ESCC metastasis. DJ-1 is a useful biomarker for predicting the efficacy of radiotherapy and a potential therapeutic target for reversing RIBE in ESCC. Schematic diagram showing the underlying mechanism that irradiation-induced secretion of DJ-1 accelerates the metastasis of bystander ESCC cells. [ABSTRACT FROM AUTHOR]

Thrombospondin 1 (TSP1) is a multifunctional matricellular protein. Recent studies demonstrate that TSP1 is highly expressed in adipose tissue (AT) and positively associated with AT inflammation and insulin resistance (IR). In this study, the contribution of different cellular sources of TSP1 to obesity-induced metabolic complications is determined by using mice with either adipocyte or myeloid/macrophage-specific deletion of TSP1 in a diet-induced obese model. The results demonstrated that neither adipocyte nor myeloid/macrophage-specific deletion of TSP1 affected the development of long-term high-fat diet-induced obesity. Adipocyte-specific deletion of TSP1 did not protect mice from obesity-induced inflammation and IR. On the contrary, obese mice with myeloid/macrophage loss of TSP1 had reduced macrophage accumulation in AT, which was accompanied with reduced inflammation and improved glucose tolerance and insulin sensitivity compared with obese control mice. Reduced macrophage-derived-TGF-β1 signaling and adipose tissue fibrosis were also observed in long-term high-fat-fed mice with myeloid/macrophage-specific TSP1 deletion. Moreover, in vitro experiments demonstrated an autocrine effect of TSP1-mediated TGF-β activation in macrophages in obesity. Collectively this study highlights the critical contribution of myeloid/macrophage-derived TSP1 to obesity-associated chronic inflammation and IR, which may serve as a new therapeutic target for metabolic disease. [ABSTRACT FROM AUTHOR]

The matricellular protein thrombospondin-1 (TSP1) is a potent inhibitor of angiogenesis. Specifically, TSP1 has been experimentally shown to inhibit signaling downstream of vascular endothelial growth factor (VEGF). The molecular mechanism of this inhibition is not entirely clear. We developed a detailed computational model of VEGF signaling to Akt-endothelial nitric oxide synthase (eNOS) to investigate the quantitative molecular mechanism of TSP1 inhibition. The model demonstrated that TSP1 acceleration of VEGFR2 degradation is sufficient to explain the inhibition of VEGFR2 and eNOS phosphorylation. However, Akt inhibition requires TSP1-induced phosphatase recruitment to VEGFR2. The model was then utilized to test various strategies for the rescue of VEGF signaling to Akt and eNOS. Inhibiting TSP1 was predicted to be not as effective as CD47 depletion in rescuing signaling to Akt. The model further predicts that combination strategy involving depletion of CD47 and inhibition of TSP1 binding to CD47 is necessary for effective recovery of signaling to eNOS. In all, computational modeling offers insight to molecular mechanisms involving TSP1 interaction with VEGF signaling and provides strategies for rescuing angiogenesis by targeting TSP1-CD47 axis. [ABSTRACT FROM AUTHOR]

VEGF signaling through VEGFR2 is a central regulator of the angiogenic response. Inhibition of VEGF signaling by the stress-induced matricellular protein TSP1 plays a role in modulating the angiogenic response to VEGF in both health and disease. TSP1 binding to CD47 inhibits VEGFR2 activation. The full implications of this inhibitory interaction are unknown. We developed a detailed rule-based computational model to inquire if TSP1- CD47 signaling through VEGF had downstream effects upon ERK1/2 and calcium. Our Simulations suggest that enhanced degradation of VEGFR2 initiated by the binding of TSP1 to CD47 is sufficient to explain the inhibition of VEGFR2 phosphorylation, calcium elevation, and ERK1/2 activation downstream of VEGF. A complementary mechanism involving the recruitment of phosphatases to the VEGFR2 complex with consequent increase in the rate of receptor dephosphorylation may augment the inhibition of the VEGF signal. The model was then utilized to simulate the effect of inhibiting external TSP1 or the depletion of CD47 as potential therapeutic strategies in restoring VEGF signaling. Results suggest that depleting CD47 is a more efficient strategy in inhibiting the effects of TSP1/CD47 on VEGF signaling. Our results highlight the utility of in silico investigations in elucidating and clarifying molecular mechanisms at the intersection of TSP1 and VEGF biology and in differentiating between competing pro-angiogenic therapeutic strategies relevant to peripheral arterial disease (PAD) and wound healing. [ABSTRACT FROM AUTHOR]

Thrombospondin 1 (TSP1) is a matricellular glycoprotein that can be secreted by many cell types. Through binding to extracellular proteins and/or cell surface receptors, TSP1 modulates a variety of cellular functions. Since its discovery in 1971, TSP1 has been found to play important roles in multiple biological processes including angiogenesis, apoptosis, latent transforming growth factor-β activation, and immune regulation. Thrombospondin 1 is also involved in regulating many organ functions. However, the role of TSP1 in liver diseases has not been extensively addressed. In this review, we summarize the findings about the possible role that TSP1 plays in chronic liver diseases focusing on non-alcoholic fatty liver diseases, liver fibrosis, and hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

Platelets and their granular contents influence both angiogenesis and breast cancer progression. This study was performed to assess the effect of breast cancer and its treatment on platelet biology and the response to inhibition of the platelet P2Y12 receptor. Receptor-specific platelet activation and inhibition was studied for three platelet-associated proteins important in cancer angiogenesis and progression, vascular endothelial growth factor (VEGF), thrombospondin1 (TSP1), and transforming growth factor beta 1 (TGF-β1). Twenty-four women with active breast cancer and 10 healthy controls not receiving antiplatelet therapy participated in the study.Ex vivoactivation of platelets in whole blood was accomplished using PAR1AP, PAR4AP, convulxin, and ADP. Platelet inhibition was accomplished using the P2Y12 receptor antagonist cangrelor (the in vitro equivalent of clopidogrel). VEGF, TSP1, and TGF-β1 were measured using standard ELISA. Platelet activation by ADP, PAR1, PAR4, and collagen receptors increased VEGF, TSP1, and TGF-β1 secretion in patients with breast cancer. Agonist-induced release of VEGF was greater in cancer patients as compared to healthy controls (p= 0.02 for ADP,p< 0.001 for PAR1AP, PAR4AP, and convulxin) despite a decrease in the efficiency of VEGF secretion in patients with breast cancer. These differences were not observed for TSP1 and TGF-β1 secretion. P2Y12 receptor inhibition decreased VEGF, TSP1, and TGF-β1 secretion. In patients with cancer, cangrelor inhibited TSP1 release to a greater extent than VEGF and TGF-β1 release. In patients with breast cancer, the magnitude of platelet inhibition achieved by cangrelor was greater than that achieved with healthy controls for all agonists and platelet proteins studied. While platelets are known to influence progression of breast cancer, our results show that breast cancer and its treatment influence the platelet phenotype by increasing the secretion of pro-angiogenic proteins following platelet activation, modulating the efficiency of platelet protein release as well as increasing the response to antiplatelet therapy. [ABSTRACT FROM AUTHOR]

Hantavirus infection is associated with two frequently fatal diseases in humans: Hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). The pathogenesis of hantavirus infection is complex and not fully understood; however, it is believed to involve virus-induced hyperinflammatory immune responses. Thrombospondin-1 (THBS1) is a large homotrimeric protein that plays a putative role in regulating blood homeostasis. Hyperresponsiveness to inflammatory stimuli has also been associated with defects in the THBS1 gene. Our data suggest that hantavirus infection of human umbilical cord vein endothelial cells (HUVEC) suppress the accumulation of THBS1 in the extracellular matrix. Additionally, this suppression is dependent on virus replication, implying a direct mechanism of action. Our data also imply that the pathogenic Andes and Hantaan strains inhibit THBS1 expression while the non-pathogenic Prospect Hill strain showed little inhibition. These observations suggest that a dysregulation of THBS1may contribute to the pathogenesis of hantavirus infection. [ABSTRACT FROM AUTHOR]

Background: A disintegrin and metallopeptidase with thrombospondin motif type 1 (ADAMTS1) is a recently discovered metalloproteinase with antiangiogenic activity. The function of ADAMTS1 in gastric cancer remains unknown. Therefore, we were interested in examining ADAMTS1 expression in human gastric cancer, as well as its possible correlation with angiogenesis. Methods: The mRNA and protein expression of ADAMTS1, thrombospondin type I (TSP1), and vascular endothelial growth factor (VEGF) was evaluated by RT-PCR and immunohistochemistry, respectively, in 56 paired tumor and normal tissue samples, and corresponding metastatic lymph nodes ( n = 42). Microvessel density (MVD) was also evaluated by immunohistochemistry. Results: ADAMTS1 mRNA and protein levels were significantly lower in primary tumors than in corresponding normal tissues, and were significantly higher in metastatic lymph nodes compared to their matched primary tumors. High ADAMTS1 mRNA and protein expression was found to be significantly associated with lymph node metastasis in primary tumors. There was a negative correlation between ADAMTS1 and VEGF mRNA and protein expression in primary gastric tumors and normal tissues. A negative correlation was also found between ADAMTS1 protein expression and MVD in primary gastric tumors. In contrast, no correlation was detected between ADAMTS1 and TSP1 mRNA and protein expression in primary gastric tumors, normal tissues, and metastatic lymph nodes. Conclusions: These findings suggest that ADAMTS1 expression is altered in primary gastric cancer and paired lymph node metastasis. In addition, ADAMTS1 has angioinhibitory effects in primary gastric cancer due to its low expression and negative correlation with VEGF and MVD. However, it appears to lose its anti-angiogenic activity in metastatic lymph nodes in gastric cancer. [ABSTRACT FROM AUTHOR]

Background: We explored the predictive significance of BRCA1, TXR1 and TSP1 expression in non-small-cell lung cancer (NSCLC) patients treated with docetaxel in association with cisplatin or gemcitabine.Methods: To analyse BRCA1, TXR1 and TSP1 mRNA expression from microdissected primary tumours of 131 patients with stage IIIB (wet) and IV NSCLC, RT-qPCR was used.Results: The mRNA levels of TXR1/TSP1 were inversely correlated (Spearman's test: -0.37; P=0.001). Low TXR1 mRNA levels were associated with higher response rate (RR; P=0.018), longer median progression-free survival (PFS; P=0.029) and median overall survival (mOS P=0.003), whereas high TSP1 expression was correlated with higher RR (P=0.035), longer PFS (P<0.001) and mOS (P<0.001). Higher BRCA1 mRNA expression was associated with higher RR (P=0.028) and increased PFS (P=0.021), but not mOS (P=0.4). Multivariate analysis demonstrated that low TXR1/high TSP1 expression was an independent factor for increased PFS (HR 0.49; 95% CI 0.32-0.76; P<0.001) and mOS (HR 0.37; 95% CI 0.2-0.58; P<0.001), whereas high BRCA1 expression was correlated with increased PFS (HR 0.53; 95% CI 0.37-0.78; P=0.001).Conclusions: These data indicate that TXR1/TSP1 and BRCA1 expression could be used for the prediction of taxanes' resistance in the treatment of NSCLC. [ABSTRACT FROM AUTHOR]

In a breast tumor xenograft model, the MCT-1 oncogene increases the in vivo tumorgenicity of MCF7 cells by promoting angiogenesis and inhibiting apoptosis. Increases in the tumor microvascular density are accompanied by a strong reduction in the levels of the angiogenesis inhibitor thrombospondin-1 (TSP1), but the mechanisms underlying this process are unknown. We show that TSP1 expression is controlled, at least in part, by post-transcriptional events. Using RNA interference to knock down the expression of the RNA-binding protein HuR in MCF7 cells as well as HuR overexpression, we demonstrate that HuR plays an important role in translation of the TSP1 mRNA. Furthermore, employing the RIP-Chip assay yielded 595 transcripts with significantly altered binding to HuR in the more tumorigenic breast cancer clones compared with the weakly tumorigenic clones. These mRNAs clustered in several pathways implicated in the transformed phenotype, such as the RAS pathway (involved in mitogenesis), the PI3K pathway (evasion of apoptosis) and pathways mediating angiogenesis and the cellular response to hypoxia. These findings demonstrate for the first time that global changes in HuR-bound mRNAs are implicated in the evolution to a more tumorigenic phenotype in an in vivo tumor model and underscore the role of global mRNA-protein interactions toward tumor progression.Oncogene (2008) 27, 6151–6163; doi:10.1038/onc.2008.215; published online 21 July 2008 [ABSTRACT FROM AUTHOR]

Angiogenesis is regulated by a balance of both angiogenic inducers and inhibitors. This study was designed to evaluate the effect of both maximum-tolerated doses (MTD) and low-dose metronomic chemotherapy (LDM) on serum vascular endothelial growth factor (VEGF), thrombospondin-1 (TSP1) and VEGFR1 concentrations in patients with advanced nonsmall cell lung cancer. Forty consecutive patients with advanced stage nonsmall cell lung cancer were included in this prospective study. Twenty patients received MTD chemotherapy including 75 mg/m2 of cisplatin and 75 mg/m2 of docetaxel on day 1. The LDM treatment consisted of cisplatin 25 mg/m2 and docetaxel 25 mg/m2 were given to other 20 patients on weeks 1, 2 and 3. Serum levels were prospectively measured in serum by ELISA at four times; before chemotherapy and at 1, 2 and 3 weeks following initiation of chemotherapy. The major finding in this study that MTD chemotherapy but not LDM chemotherapy resulted in significant changes in VEGFR1 and TSP1 serum levels. Due to the effect of LDM chemotherapy, we showed no statistically significant change in patients for all serum VEGF, TSP1 and VEGFR1 levels. Similarly, serum VEGF levels did not also change under MTD chemotherapy. The MTD chemotherapy induced significant and long-lasting increase of TSP1 levels and decrease of VEGFR1 levels that persisted for at least 3 weeks after the chemotherapy initiation. No significant correlations were found between serum VEGF and TSP1 levels in cancer patients treated with both LDM and MTD chemotherapy. The circulating angiogenic balance (TSP1/VEGF) is decreased in cancer patients ( P = 0.039). The continuous/metronomic chemotherapy may not achieve a more pronounced antiangiogenic effect than MTD-scheduling chemotherapy. Future studies involving a larger number of patients are needed to confirm the present findings. [ABSTRACT FROM AUTHOR]

Human THROMBOSPONDIN-1 play versatile roles in platelet aggregation, angiogenesis, and tumorigenesis, which forms a disulfide-linked homotrimeric complex. Here we reported that the genomic lotus of TSP1 also transcribes a natural antisense transcript (NAT) with an overlapping and reverse complement region against TSP1 . The NAT of TSP1 was expressed in human testis, lung, thymus, colon, placenta, kidney and skeleton muscle, revealed by PCR amplification. It was also expressed in some tumor cell lines. The identification of NAT of TSP1 would be of significant importance to understand the functions of TSP1 , and it would also suggest the potential attempt of using RNA interference for related tumor therapy, for instance, breast cancer. [ABSTRACT FROM AUTHOR]

Thrombospondin-1 (TSP1) is a potent peptide shown in some tumor systems to be linked with angiogenesis. Epigenetic alteration of TSP1 has been reported in various primary tumors. However, the expression pattern of TSP1 has not been characterized in gastric carcinoma. We measured levels of TSP1 mRNA expression using quantitative RT-PCR in 30 gastric carcinomas and 10 non-neoplastic mucosae. In addition, we examined the correlation of the levels of TSP1 mRNA expression levels with promoter methylation status of TSP1 monitored by methylation-specific PCR as well as p53 mutation status detected by PCR-single-strand conformation polymorphism. Promoter hypermethylation of the TSP1 gene was found in 10 (33%) of 30 gastric carcinomas, and TSP1 mRNA expression levels were associated with promoter hypermethylation of TSP1 (p = 0.017; Mann-Whitney U test). p53 mutation was found in 5 (17%) of 30 gastric carcinomas, however, TSP1 mRNA expression was not associated with p53 mutation status (p = 0.858; Mann-Whitney U test). There was no correlation between TSP1 mRNA expression levels and T grade, N grade, tumor stage, or histological type. Our results suggest that transcriptional inactivation of TSP1 by aberrant DNA methylation of the promoter region may participate partly in stomach carcinogenesis through TSP1 down-regulation.Copyright © 2003 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Simple Summary: Triple-negative breast cancer (TNBC) is associated with a poor prognosis, and the development of better therapeutic strategies is required. Herein, we investigated the role of the anti-angiogenic thrombospondin-1 (TSP1) in TNBC. TSP1 expression in tumor biopsies from TNBC patients was associated with a bad prognosis and a weak content of tumor-infiltrating lymphocytes (TILs). In the 4T1 mouse TNBC model, TSP1 knockdown reduced TGF-β activation and enhanced the content of TILs. Moreover, TSP1 knockdown decreased lung metastasis in syngeneic Balb/c immunocompetent mice but not in immunodeficient nude mice. Finally, TSP1 knockdown enhanced anti-PD-1 immunotherapy efficacy. Thus, targeting TSP1 may be considered as a putative therapeutic strategy in TNBC in combination with immunotherapy. Triple-negative breast cancer (TNBC) is notoriously aggressive with a high metastatic potential, and targeted therapies are lacking. Using transcriptomic and histologic analysis of TNBC samples, we found that a high expression of thrombospondin-1 (TSP1), a potent endogenous inhibitor of angiogenesis and an activator of latent transforming growth factor beta (TGF-β), is associated with (i) gene signatures of epithelial–mesenchymal transition and TGF-β signaling, (ii) metastasis and (iii) a reduced survival in TNBC patients. In contrast, in tumors expressing low levels of TSP1, gene signatures of interferon gamma (IFN-γ) signaling and lymphocyte activation were enriched. In TNBC biopsies, TSP1 expression inversely correlated with the CD8+ tumor-infiltrating lymphocytes (TILs) content. In the 4T1 metastatic mouse model of TNBC, TSP1 silencing did not affect primary tumor development but, strikingly, impaired metastasis in immunocompetent but not in immunodeficient nude mice. Moreover, TSP1 knockdown increased tumor vascularization and T lymphocyte infiltration and decreased TGF-β activation in immunocompetent mice. Noteworthy was the finding that TSP1 knockdown increased CD8+ TILs and their programmed cell death 1 (PD-1) expression and sensitized 4T1 tumors to anti-PD-1 therapy. TSP1 inhibition might thus represent an innovative targeted approach to impair TGF-β activation and breast cancer cell metastasis and improve lymphocyte infiltration in tumors, and immunotherapy efficacy in TNBC. [ABSTRACT FROM AUTHOR]

Pathological angiogenesis contributes to cancer progression and chronic inflammatory diseases. In inflammatory bowel disease, the microvasculature expands by intussusceptive angiogenesis (IA), a poorly characterized mechanism involving increased blood flow and splitting of pre‐existing capillaries. In this report, mice lacking the protease MT1‐MMP in endothelial cells (MT1iΔEC) presented limited IA in the capillary plexus of the colon mucosa assessed by 3D imaging during 1% DSS‐induced colitis. This resulted in better tissue perfusion, preserved intestinal morphology, and milder disease activity index. Combined in vivo intravital microscopy and lentiviral rescue experiments with in vitro cell culture demonstrated that MT1‐MMP activity in endothelial cells is required for vasodilation and IA, as well as for nitric oxide production via binding of the C‐terminal fragment of MT1‐MMP substrate thrombospondin‐1 (TSP1) to CD47/αvβ3 integrin. Moreover, TSP1 levels were significantly higher in serum from IBD patients and in vivo administration of an anti‐MT1‐MMP inhibitory antibody or a nonamer peptide spanning the αvβ3 integrin binding site in TSP1 reduced IA during mouse colitis. Our results identify MT1‐MMP as a new actor in inflammatory IA and a promising therapeutic target for inflammatory bowel disease. Synopsis: Inflammatory bowel disease comprising ulcerative colitis and Crohn's disease does not have a universal efficient therapy. This study identifies the molecular axis MT1‐MMP/thrombospondin‐1/αvβ3 integrin/nitric oxide as a target to reduce inflammatory intussusceptive angiogenesis and improve colitis. Early expansion of the capillaries in the intestinal mucosa during colitis was caused by intussusceptive/splitting angiogenesis (IA).Deletion of the protease MT1‐MMP from endothelial cells reduced IA and colitis severity.Thrombospondin‐1 (TSP1) processing by MT1‐MMP promoted nitric oxide production, vasodilation and IA.High levels of TSP1 were found in sera from patients suffering low active IBD.Targeting MT1‐MMP/TSP1/αvβ3 integrin/nitric oxide pathway by monoclonal antibodies or minipump‐delivered peptides decreased IA and ameliorates colitis. [ABSTRACT FROM AUTHOR]

A correction to the article "Inhibition of VEGFR2 Activation and Its Downstream Signaling to ERK1/2 and Calcium by Thrombospondin-1 (TSP1): In silico Investigation" which appeared in the 2017 issue is presented.