NDRG1 activates VEGF-A-induced angiogenesis through PLCγ1/ERK signaling in mouse vascular endothelial cells

A mechanistic systems biology model of brain microvascular endothelial cell signaling reveals dynamic pathway-based therapeutic targets for brain ischemia

Ischemic stroke is a significant threat to human health. Currently, there is a lack of effective treatments for stroke, and progress in new neuron-centered drug target development is relatively slow. On the other hand, studies have demonstrated that brain microvascular endothelial cells (BMECs) are crucial components of the neurovascular unit and play pivotal roles in ischemic stroke progression. To better understand the complex multifaceted roles of BMECs in the regulation of ischemic stroke pathophysiology and facilitate BMEC-based drug target discovery, we utilized a transcriptomics-informed systems biology modeling approach and constructed a mechanism-based computational multipathway model to systematically investigate BMEC function and its modulatory potential. Extensive multilevel data regarding complex BMEC pathway signal transduction and biomarker expression under various pathophysiological conditions were used for quantitative model calibration and validation, and we generated dynamic BMEC phenotype maps in response to various stroke-related stimuli to identify potential determinants of BMEC fate under stress conditions. Through high-throughput model sensitivity analyses and virtual target perturbations in model-based single cells, our model predicted that targeting succinate could effectively reverse the detrimental cell phenotype of BMECs under oxygen and glucose deprivation/reoxygenation, a condition that mimics stroke pathogenesis, and we experimentally validated the utility of this new target in terms of regulating inflammatory factor production, free radical generation and tight junction protection in vitro and in vivo. Our work is the first that complementarily couples transcriptomic analysis with mechanistic systems-level pathway modeling in the study of BMEC function and endothelium-based therapeutic targets in ischemic stroke.

VEGF-dependent testicular vascularisation involves MEK1/2 signalling and the essential angiogenesis factors, SOX7 and SOX17

BACKGROUND

Abnormalities of in utero testis development are strongly associated with reproductive health conditions, including male infertility and testis cancer. In mouse testes, SOX9 and FGF9 support Sertoli cell development, while VEGF signalling is essential for the establishment of vasculature. The mitogen-activated protein kinase (MAPK) pathway is a major signalling cascade, essential for cell proliferation, differentiation and activation of Sry during primary sex-determination, but little is known about its function during fetal testis morphogenesis. We explored potential functions of MAPK signalling immediately after the establishment of testis cords in embryonic day (E)12.5 Oct4-eGFP transgenic mouse testes cultured using a MEK1/2 inhibitor.

RESULTS

RNA sequencing in isolated gonadal somatic cells identified 116 and 114 differentially expressed genes after 24 and 72 h of MEK1/2 inhibition, respectively. Ingenuity Pathway Analysis revealed an association of MEK1/2 signalling with biological functions such as angiogenesis, vasculogenesis and cell migration. This included a failure to upregulate the master transcriptional regulators of vascular development, Sox7 and Sox17, VEGF receptor genes, the cell adhesion factor gene Cd31 and a range of other endothelial cell markers such as Cdh5 (encoding VE-cadherin) and gap junction genes Gja4 and Gja5. In contrast, only a small number of Sertoli cell enriched genes were affected. Immunofluorescent analyses of control testes revealed that the MEK1/2 downstream target, ERK1/2 was phosphorylated in endothelial cells and Sertoli cells. Inhibition of MEK1/2 eliminated pERK1/2 in fetal testes, and CD31, VE-cadherin, SOX7 and SOX17 and endothelial cells were lost. Consistent with a role for VEGF in driving endothelial cell development in the testis, inhibition of VEGFR also abrogated pERK1/2 and SOX7 and SOX17 expressing endothelial cells. Moreover, while Sertoli cell proliferation and localisation to the testis cord basement membrane was disrupted by inhibition of MEK1/2, it was unaffected by VEGFR inhibition. Instead, inhibition of FGF signalling compromised Sertoli cell proliferation and localisation to the testis cord basement membrane.

CONCLUSIONS

Together, our data highlight an essential role for VEGF-dependent MEK1/2 signalling in promoting vasculature and indicate that FGF signalling through MEK1/2 regulates Sertoli cell organisation in the developing mouse testis.

Elevated expression of N-myc downstream regulated gene 1 protein in glioblastomas reflects tumor angiogenesis and poor patient prognosis

N-myc downstream regulated gene 1 (NDRG1) is a member of the NDRG family, of which four members (NDRG1, NDRG2, NDRG3, and NDRG4) have been identified. NDRG1 is repressed by c-MYC and N-MYC proto-oncogenes. NDRG1 is translated into a 43 kDa protein that is associated with the regulation of cellular stress responses, proliferation, and differentiation. In this study, we aimed to clarify the relationship between progression of glioblastoma (GB) IDH-wildtype and NDRG1 expression in tumor cells. We assessed the expression of NDRG1 in 41 GBs using immunostaining and evaluated its prognostic significance. NDRG1 expression by GBs was evaluated using Histoscore, which showed high and low scores in 23 and 18 cases, respectively. NDRG1-positive cells were strongly expressed in Ki-67 labeled proliferating tumor cells and CD105 positive proliferating microvessels around the area of palisading necrosis. Statistical analyses showed lower survival rates in the high-score group than the low-score group (P < 0.01). This study indicated that overexpression of NDRG1 by GB reflects tumor angiogenesis and poor patient prognosis.

Harnessing the Coil Electrospinning Method for Fabricating Superflexible and Multiscale-Patterned Fibrous Tubular Scaffolds with Topographical Features

The fibrous tubular scaffold (FTS) has potential as a vascular graft; however, its clinical application is hindered by insufficient mechanical properties. Inadequate mechanical properties of vascular grafts can lead to some serious side effects such as intimal hyperplasia, luminal expansion, and blood thrombogenicity. In this study, we developed a novel fibrous tubular scaffold comprising multiscale fibers to ensure superior mechanical properties. Our novel approach involves a one-step manufacturing method that can fabricate the superflexible fibrous tubular scaffold (SF-FTS) with topographical features via a modified electrospinning setup. We investigated the effect of humidity and temperature during the fabrication process on the formation of multiscale fibers. It was demonstrated that the incorporation of multiscale fibers and topographical features significantly enhances the mechanical properties of FTS. The mechanical advantages of SF-FTS were confirmed through the kinking resistance test, compressive test, and in vivo experiments. Additionally, we explored the interaction between the multiscale fibers and human umbilical vein endothelial cells (HUVECs) behavior. Our results suggest a novel strategy for fabricating FTS with advanced mechanical properties, and the designed SF-FTS holds promise as a potential candidate for clinical applications.

Research progress in tumor angiogenesis and drug resistance in breast cancer

Angiogenesis is considered a hallmark pathophysiological process in tumor development. Aberrant vasculature resulting from tumor angiogenesis plays a critical role in the development of resistance to breast cancer treatments, via exacerbation of tumor hypoxia, decreased effective drug concentrations within tumors, and immune-related mechanisms. Antiangiogenic therapy can counteract these breast cancer resistance factors by promoting tumor vascular normalization. The combination of antiangiogenic therapy with chemotherapy, targeted therapy, or immunotherapy has emerged as a promising approach for overcoming drug resistance in breast cancer. This review examines the mechanisms associated with angiogenesis and the interactions among tumor angiogenesis, the hypoxic tumor microenvironment, drug distribution, and immune mechanisms in breast cancer. Furthermore, this review provides a comprehensive summary of specific antiangiogenic drugs, and relevant studies assessing the reversal of drug resistance in breast cancer. The potential mechanisms underlying these interventions are discussed, and prospects for the clinical application of antiangiogenic therapy to overcome breast cancer treatment resistance are highlighted.

Regulation of VEGF-A expression and VEGF-A-targeted therapy in malignant tumors

Vascular endothelial growth factor A (VEGF-A), a highly conserved dimeric glycoprotein, is a key regulatory gene and a marker molecule of angiogenesis. The upregulation of VEGF-A facilitates the process of tumor vascularization, thereby fostering the initiation and progression of malignant neoplasms. Many genes can adjust the angiogenesis of tumors by changing the expression of VEGF-A. In addition, VEGF-A also exhibits immune regulatory properties, which directly or indirectly suppresses the antitumor activity of immune cells. The emergence of VEGF-A-targeted therapy alone or in rational combinations has revolutionized the treatment of various cancers. This review discusses how diverse mechanisms in various tumors regulate VEGF-A expression to promote tumor angiogenesis and the role of VEGF-A in tumor immune microenvironment. The application of drugs targeting VEGF-A in tumor therapy is also summarized including antibody molecule drugs and traditional Chinese medicine.

Single-Cell RNA Sequencing Reveals That Adaptation of Human Aortic Endothelial Cells to Antiproliferative Therapies Is Modulated by Flow-Induced Shear Stress

BACKGROUND

Endothelial cells (ECs) are capable of quickly responding in a coordinated manner to a wide array of stresses to maintain vascular homeostasis. Loss of EC cellular adaptation may be a potential marker for cardiovascular disease and a predictor of poor response to endovascular pharmacological interventions such as drug-eluting stents. Here, we report single-cell transcriptional profiling of ECs exposed to multiple stimulus classes to evaluate EC adaptation.

METHODS

Human aortic ECs were costimulated with both pathophysiological flows mimicking shear stress levels found in the human aorta (laminar and turbulent, ranging from 2.5 to 30 dynes/cm2) and clinically relevant antiproliferative drugs, namely paclitaxel and rapamycin. EC state in response to these stimuli was defined using single-cell RNA sequencing.

RESULTS

We identified differentially expressed genes and inferred the TF (transcription factor) landscape modulated by flow shear stress using single-cell RNA sequencing. These flow-sensitive markers differentiated previously identified spatially distinct subpopulations of ECs in the murine aorta. Moreover, distinct transcriptional modules defined flow- and drug-responsive EC adaptation singly and in combination. Flow shear stress was the dominant driver of EC state, altering their response to pharmacological therapies.

CONCLUSIONS

We showed that flow shear stress modulates the cellular capacity of ECs to respond to paclitaxel and rapamycin administration, suggesting that while responding to different flow patterns, ECs experience an impairment in their transcriptional adaptation to other stimuli.

NDRG1 promotes endothelial dysfunction and hypoxia-induced pulmonary hypertension by targeting TAF15

Background

Pulmonary hypertension (PH) represents a threatening pathophysiologic state that can be induced by chronic hypoxia and is characterized by extensive vascular remodeling. However, the mechanism underlying hypoxia-induced vascular remodeling is not fully elucidated.

Methods and Results

By using quantitative polymerase chain reactions, western blotting, and immunohistochemistry, we demonstrate that the expression of N-myc downstream regulated gene-1 (NDRG1) is markedly increased in hypoxia-stimulated endothelial cells in a time-dependent manner as well as in human and rat endothelium lesions. To determine the role of NDRG1 in endothelial dysfunction, we performed loss-of-function studies using NDRG1 short hairpin RNAs and NDRG1 over-expression plasmids. In vitro, silencing NDRG1 attenuated proliferation, migration, and tube formation of human pulmonary artery endothelial cells (HPAECs) under hypoxia, while NDRG1 over-expression promoted these behaviors of HPAECs. Mechanistically, NDRG1 can directly interact with TATA-box binding protein associated factor 15 (TAF15) and promote its nuclear localization. Knockdown of TAF15 abrogated the effect of NDRG1 on the proliferation, migration and tube formation capacity of HPAECs. Bioinformatics studies found that TAF15 was involved in regulating PI3K-Akt, p53, and hypoxia-inducible factor 1 (HIF-1) signaling pathways, which have been proved to be PH-related pathways. In addition, vascular remodeling and right ventricular hypertrophy induced by hypoxia were markedly alleviated in NDRG1 knock-down rats compared with their wild-type littermates.

Conclusions

Taken together, our results indicate that hypoxia-induced upregulation of NDRG1 contributes to endothelial dysfunction through targeting TAF15, which ultimately contributes to the development of hypoxia-induced PH.

HSPA12A Stimulates p38/ERK-AP-1 Signaling to Promote Angiogenesis and Is Required for Functional Recovery Postmyocardial Infarction

Angiogenesis plays a critical role in wound healing postmyocardial infarction (MI). However, there is still a lack of ideal angiogenic therapeutics for rescuing ischemic hearts clinically, suggesting that a more understanding regarding angiogenesis regulation is urgently needed. Heat shock protein A12A (HSPA12A) is an atypical member of the HSP70 family. Here, we demonstrated that HSPA12A was upregulated during endothelial tube formation, a characteristic of in vitro angiogenesis. Intriguingly, overexpression of HSPA12A promoted in vitro angiogenic characteristics including proliferation, migration, and tube formation of endothelial cells. By contrast, deficiency of HSPA12A impaired myocardial angiogenesis and worsened cardiac dysfunction post-MI in mice. The expression of genes related to angiogenesis (VEGF, VEGFR2, and Ang-1) was decreased by HSPA12A deficiency in MI hearts of mice, whereas their expression was increased by HSPA12A overexpression in endothelial cells. HSPA12A overexpression in endothelial cells increased phosphorylation levels and nuclear localization of AP-1, a transcription factor dominating angiogenic gene expression. Also, HSPA12A increased p38 and ERK phosphorylation levels, whereas inhibition of p38 or ERKs diminished the HSPA12A-promoted AP-1 phosphorylation and nuclear localization, as well as VEGF and VEGFR2 expression in endothelial cells. Notably, inhibition of either p38 or ERKs diminished the HSPA12A-promoted in vitro angiogenesis characteristics. The findings identified HSPA12A as a novel angiogenesis activator, and HSPA12A might represent a viable strategy for the management of myocardial healing in patients with ischemic heart diseases.

The genetic deletion of the Dual Specificity Phosphatase 3 (DUSP3) attenuates kidney damage and inflammation following ischaemia/reperfusion injury in mouse

AIM

Dual Specificity Phosphatase 3 (DUSP3) regulates the innate immune response, with a putative role in angiogenesis. Modulating inflammation and perfusion contributes to renal conditioning against ischaemia/reperfusion (I/R). We postulate that the functional loss of DUSP3 is associated with kidney resistance to I/R.

METHODS

Ten C57BL/6 male WT and Dusp3^-/- mice underwent right nephrectomy and left renal I/R (30 min/48 hours). Renal injury was assessed based on serum levels of urea (BUN) and Jablonski score. The expression of CD31 and VEGF vascular markers was quantified by RT-qPCR and immuno-staining. Renal resistivity index (RRI) was measured in vivo by Doppler ultrasound. Comparative phosphoproteomics was conducted using IMAC enrichment of phosphopeptides. Inflammatory markers were quantified at both mRNA and protein levels in ischaemic vs non-ischaemic kidneys in WT vs Dusp3^-/- .

RESULTS

At baseline, we located DUSP3 in renal glomeruli and endothelial cells. CD31-positive vascular network was significantly larger in Dusp3^-/- kidneys compared to WT, with a lower RRI in Dusp3^-/- mice. Following I/R, BUN and Jablonski score were significantly lower in Dusp3^-/- vs WT mice. Phosphoproteomics highlighted a down-regulation of inflammatory pathways and up-regulation of phospho-sites involved in cell metabolism and VEGF-related angiogenesis in Dusp3^-/- vs WT ischaemic kidneys. Dusp3^-/- ischaemic kidneys showed decreased mRNA levels of CD11b, TNF-α, KIM-1, IL-6, IL-1β and caspase-3 compared to controls. The numbers of PCNA-, F4-80- and CD11b-positive cells were reduced in Dusp3^-/- vs WT kidneys post-I/R.

CONCLUSION

Genetic inactivation of Dusp3 is associated with kidney conditioning against I/R, possibly due to attenuated inflammation and improved perfusion.

Downregulation of miR-491-5p promotes neovascularization after traumatic brain injury

MicroRNA-491-5p (miR-491-5p) plays an important role in regulating cell proliferation and migration; however, the effect of miR-491-5p on neovascularization after traumatic brain injury remains poorly understood. In this study, a controlled cortical injury model in C57BL/6 mice and an oxygen-glucose deprivation model in microvascular endothelial cells derived from mouse brain were established to simulate traumatic brain injury in vivo and in vitro, respectively. In the in vivo model, quantitative real-time-polymerase chain reaction results showed that the expression of miR-491-5p increased or decreased following the intracerebroventricular injection of an miR-491-5p agomir or antagomir, respectively, and the expression of miR-491-5p decreased slightly after traumatic brain injury. To detect the neuroprotective effects of miR-491-p, neurological severity scores, Morris water maze test, laser speckle techniques, and immunofluorescence staining were assessed, and the results revealed that miR-491-5p downregulation alleviated neurological dysfunction, promoted the recovery of regional cerebral blood flow, increased the number of lectin-stained microvessels, and increased the survival of neurons after traumatic brain injury. During the in vitro experiments, the potential mechanism of miR-491-5p on neovascularization was explored through quantitative real-time-polymerase chain reaction, which showed that miR-491-5p expression increased or decreased in brain microvascular endothelial cells after transfection with an miR-491-5p mimic or inhibitor, respectively. Dual-luciferase reporter and western blot assays verified that metallothionein-2 was a target gene for miR-491-5p. Cell counting kit 8 (CCK-8) assay, flow cytometry, and 2?,7?-dichlorofluorescein diacetate (DCFH-DA) assay results confirmed that the downregulation of miR-491-5p increased brain microvascular endothelial cell viability, reduced cell apoptosis, and alleviated oxidative stress under oxygen-glucose deprivation conditions. Cell scratch assay, Transwell assay, tube formation assay, and western blot assay results demonstrated that miR-491-5p downregulation promoted the migration, proliferation, and tube formation of brain microvascular endothelial cells through a metallothionein-2-dependent hypoxia-inducible factor-1α/vascular endothelial growth factor pathway. These findings confirmed that miR-491-5p downregulation promotes neovascularization, restores cerebral blood flow, and improves the recovery of neurological function after traumatic brain injury. The mechanism may be mediated through a metallothionein-2-dependent hypoxia-inducible factor-1α/vascular endothelial growth factor signaling pathway and the alleviation of oxidative stress. All procedures were approved by Ethics Committee of the First Affiliated Hospital of Chongqing Medical University, China (approval No. 2020-304) on June 22, 2020.

The Role of the VEGF Family in Coronary Heart Disease

The vascular endothelial growth factor (VEGF) family, the regulator of blood and lymphatic vessels, is mostly investigated in the tumor and ophthalmic field. However, the functions it enjoys can also interfere with the development of atherosclerosis (AS) and further diseases like coronary heart disease (CHD). The source, regulating mechanisms including upregulation and downregulation, target cells/tissues, and known functions about VEGF-A, VEGF-B, VEGF-C, and VEGF-D are covered in the review. VEGF-A can regulate angiogenesis, vascular permeability, and inflammation by binding with VEGFR-1 and VEGFR-2. VEGF-B can regulate angiogenesis, redox, and apoptosis by binding with VEGFR-1. VEGF-C can regulate inflammation, lymphangiogenesis, angiogenesis, apoptosis, and fibrogenesis by binding with VEGFR-2 and VEGFR-3. VEGF-D can regulate lymphangiogenesis, angiogenesis, fibrogenesis, and apoptosis by binding with VEGFR-2 and VEGFR-3. These functions present great potential of applying the VEGF family for treating CHD. For instance, angiogenesis can compensate for hypoxia and ischemia by growing novel blood vessels. Lymphangiogenesis can degrade inflammation by providing exits for accumulated inflammatory cytokines. Anti-apoptosis can protect myocardium from impairment after myocardial infarction (MI). Fibrogenesis can promote myocardial fibrosis after MI to benefit cardiac recovery. In addition, all these factors have been confirmed to keep a link with lipid metabolism, the research about which is still in the early stage and exact mechanisms are relatively obscure. Because few reviews have been published about the summarized role of the VEGF family for treating CHD, the aim of this review article is to present an overview of the available evidence supporting it and give hints for further research.

PI3K-AKT, JAK2-STAT3 pathways and cell-cell contact regulate maspin subcellular localization

Background

Maspin (SERPINB5) is a potential tumor suppressor gene with pleiotropic biological activities, including regulation of cell proliferation, death, adhesion, migration and gene expression. Several studies indicate that nuclear localization is essential for maspin tumor suppression activity. We have previously shown that the EGFR activation leads to maspin nuclear localization in MCF-10A cells. The present study investigated which EGFR downstream signaling molecules are involved in maspin nuclear localization and explored a possible role of cell–cell contact in this process.

Methods

MCF-10A cells were treated with pharmacological inhibitors against EGFR downstream pathways followed by EGF treatment. Maspin subcellular localization was determined by immunofluorescence. Proteomic and interactome analyses were conducted to identify maspin-binding proteins in EGF-treated cells only. To investigate the role of cell–cell contact these cells were either treated with chelating agents or plated on different cell densities. Maspin and E-cadherin subcellular localization was determined by immunofluorescence.

Results

We found that PI3K-Akt and JAK2-STAT3, but not MAP kinase pathway, regulate EGF-induced maspin nuclear accumulation in MCF-10A cells. We observed that maspin is predominantly nuclear in sparse cell culture, but it is redistributed to the cytoplasm in confluent cells even in the presence of EGF. Proteomic and interactome results suggest a role of maspin on post-transcriptional and translation regulation, protein folding and cell–cell adhesion.

Conclusions

Maspin nuclear accumulation is determined by an interplay between EGFR (via PI3K-Akt and JAK2-STAT3 pathways) and cell–cell contact.

Identification of VEGFA-centric temporal hypoxia-responsive dynamic cardiopulmonary network biomarkers

AIMS

Hypoxia, a pathophysiological condition, is profound in several cardiopulmonary diseases (CPD). Every individual's lethality to a hypoxia state differs in terms of hypoxia exposure time, dosage units and dependent on the individual's genetic makeup. Most of the proposed markers for CPD were generally aim to distinguish disease samples from normal samples. Although, as per the 2018 GOLD guidelines, clinically useful biomarkers for several cardio pulmonary disease patients in stable condition have yet to be identified. We attempt to address these key issues through the identification of Dynamic Network Biomarkers (DNB) to detect hypoxia induced early warning signals of CPD before the catastrophic deterioration.

MATERIALS AND METHODS

The human microvascular endothelial tissues microarray datasets (GSE11341) of lung and cardiac expose to hypoxia (1% O₂) for 3, 24 and 48 h were retrieved from the public repository. The time dependent differentially expressed genes were subjected to tissue specificity and promoter analysis to filtrate the noise levels in the networks and to dissect the tissue specific hypoxia induced genes. These filtered out genes were used to construct the dynamic segmentation networks. The hypoxia induced dynamic differentially expressed genes were validated in the lung and heart tissues of male rats. These rats were exposed to hypobaric hypoxia (simulated altitude of 25,000 or PO₂ - 282 mm of Hg) progressively for 3, 24 and 48 h.

KEY FINDINGS

To identify the temporal key genes regulated in hypoxia, we ranked the dominant genes based on their consolidated topological features from tissue specific networks, time dependent networks and dynamic networks. Overall topological ranking described VEGFA as a single node dynamic hub and strongly communicated with tissue specific genes to carry forward their tissue specific information. We named this type of VEGFAcentric dynamic networks as "V-DNBs". As a proof of principle, our methodology helped us to identify the V-DNBs specific for lung and cardiac tissues namely V-DNB^L and V-DNB^C respectively.

SIGNIFICANCE

Our experimental studies identified VEGFA, SLC2A3, ADM and ENO2 as the minimum and sufficient candidates of V-DNB^L. The dynamic expression patterns could be readily exploited to capture the pre disease state of hypoxia induced pulmonary vascular remodelling. Whereas in V-DNB^C the minimum and sufficient candidates are VEGFA, SCL2A3, ADM, NDRG1, ENO2 and BHLHE40. The time dependent single node expansion indicates V-DNB^C could also be the pre disease state pathological hallmark for hypoxia-associated cardiovascular remodelling. The network cross-talk and expression pattern between V-DNB^L and V-DNB^C are completely distinct. On the other hand, the great clinical advantage of V-DNBs for pre disease predictions, a set of samples during the healthy condition should suffice. Future clinical studies might further shed light on the predictive power of V-DNBs as prognostic and diagnostic biomarkers for CPD.

Exosomes derived from plasma: promising immunomodulatory agents for promoting angiogenesis to treat radiation-induced vascular dysfunction

Ionizing radiation (IR)-induced vascular disorders slow down tissue regeneration. Exosomes derived from plasma exhibit potential to promote angiogenesis; meanwhile, the immune microenvironment plays a significant role in the process. This study aimed to test the hypothesis that plasma exosomes promote angiogenesis in irradiated tissue by mediating the immune microenvironment. First, we explored the impact of IR on macrophages. We found that cell viability and capacity for promoting angiogenesis were decreased in irradiated macrophages compared to control macrophages. Then, we isolated and characterized rat plasma-derived exosomes (RP-Exos) which were defined as 40-160 nm extracellular vesicles extracted from rat plasma. Afterward, we evaluated the effects of RP-Exos on the behaviors of irradiated macrophages. Our results show that RP-Exos promoted cell proliferation. More importantly, we found that RP-Exos stimulated the immune microenvironment in a manner that improved the angiogenesis-related genes and proteins of irradiated macrophages. The supernatant of macrophage cell cultures was used as conditioned medium to treat human primary umbilical vein endothelial cells, further confirming the pro-angiogenic ability of macrophages receiving RP-Exo intervention. RP-Exos were used in vivo to treat irradiated skin or calvarial defects in irradiated Sprague-Dawley male rats. The results indicated the ability of RP-Exos to enhance angiogenesis and promote tissue regeneration. Our research suggested the potential of plasma exosomes to be used as immunomodulatory agents with angiogenic capacity to treat radiation-associated vascular disorders and facilitate tissue repair.

Angiogenesis regulation by microRNAs and long non-coding RNAs in human breast cancer

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are capable of regulating gene expression post-transcriptionally. Since the past decade, a number of in vitro, in vivo, and clinical studies reported the roles of these non-coding RNAs (ncRNAs) in regulating angiogenesis, an important cancer hallmark that is associated with metastases and poor prognosis. The specific roles of various miRNAs and lncRNAs in regulating angiogenesis in breast cancer, with particular focus on the downstream targets and signalling pathways regulated by these ncRNAs will be discussed in this review. In light of the recent trend in exploiting ncRNAs as cancer therapeutics, the potential use of miRNAs and lncRNAs as biomarkers and novel therapeutic agent against angiogenesis was also discussed.

Crystal and solution structure of NDRG1, a membrane-binding protein linked to myelination and tumour suppression

N-myc downstream-regulated gene 1 (NDRG1) is a tumour suppressor involved in vesicular trafficking and stress response. NDRG1 participates in peripheral nerve myelination, and mutations in the NDRG1 gene lead to Charcot-Marie-Tooth neuropathy. The 43-kDa NDRG1 is considered as an inactive member of the α/β hydrolase superfamily. In addition to a central α/β hydrolase fold domain, NDRG1 consists of a short N terminus and a C-terminal region with three 10-residue repeats. We determined the crystal structure of the α/β hydrolase domain of human NDRG1 and characterised the structure and dynamics of full-length NDRG1. The structure of the α/β hydrolase domain resembles the canonical α/β hydrolase fold with a central β sheet surrounded by α helices. Small-angle X-ray scattering and CD spectroscopy indicated a variable conformation for the N- and C-terminal regions. NDRG1 binds to various types of lipid vesicles, and the conformation of the C-terminal region is modulated upon lipid interaction. Intriguingly, NDRG1 interacts with metal ions, such as nickel, but is prone to aggregation in their presence. Our results uncover the structural and dynamic features of NDRG1, as well as elucidate its interactions with metals and lipids, and encourage studies to identify a putative hydrolase activity of NDRG1. DATABASES: The coordinates and structure factors for the crystal structure of human NDRG1 were deposited to PDB (PDB ID: 6ZMM).

NT5DC2 knockdown inhibits colorectal carcinoma progression by repressing metastasis, angiogenesis and tumor-associated macrophage recruitment: A mechanism involving VEGF signaling

Colorectal cancer (CRC) is one of the most commonly diagnosed tumors among human worldwide. Angiogenesis and tumor-associated macrophage (TAM) recruitment are closely associated with CRC development. Nevertheless, the mechanisms revealing CRC progression are still not fully understood. 5'-Nucleotidase domain containing 2 (NT5DC2), a member of the NT5DC family, modulates various cellular events to mediate tumor growth, and thus serves as a disgnostic biomarker. Here, we explored the potential of NT5DC2 on tumor progression in CRC. We first found that NT5DC2 expression was significantly up-regulated in CRC tissues and cell lines. CRC patients with higher NT5DC2 expression showed poor overall survival. Furthermore, CRC cell lines stably transfected with shNT5DC2 lentivirus plasmids exhibited markedly reduced cell proliferation, migration and invasion compared with the negative control group. Hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor A (VEGF-A) expression levels were remarkably reduced in CRC cells with NT5DC2 deletion, along with evidently reduced tube formation in the HUVECs cultured in the collected conditional medium. The expression levels of CC chemokine ligand 2 (CCL2) and its receptor CCR2 were found to be greatly down-regulated in CRC cells transfected with shNT5DC2. Moreover, NT5DC2 knockdown markedly suppressed the activation of protein kinase-B/nuclear transcription factor κB (AKT/NF-κB) signaling in CRC cells. Furthermore, we found that NT5DC2 deletion obviously reduced the TAM recruitments through suppressing CCL2/CCR2 and AKT/NF-κB signaling pathways. Intriguingly, our in vitro experiments demonstrated that VEGF reduction was necessary for shNT5DC2-inhibited cell proliferation, migration, invasion, angiogenesis and TAM recruitment. In vivo studies also confirmed that NT5DC2 knockdown effectively reduced the tumor growth and VEGF expression in a xonegraft mouse model with CRC. Lung metastasis of CRC cells was also hindered by NT5DC2 deletion in vivo. Collectively, our results indicated a previously unrecognized NT5DC2/VEGF/CCL2 axis involved in CRC development and metastasis.