Hypoxia-induced Angiogenesis Research Articles

Opticin Ameliorates Hypoxia-Induced Retinal Angiogenesis by Suppression of Integrin α2-I Domain-Collagen Complex Formation and RhoA/ROCK1 Signaling.

PurposeIt was previously demonstrated that opticin (OPTC) inhibits the collagen-induced promotion of bioactivities of human retinal vascular endothelial cells (hRVECs). The present in vivo study aimed to further investigate the regulatory role of opticin in vitreous collagen-mediated retinal neovascularization and to elucidate its regulatory mechanisms with regard to integrin α2-I domain–GXXGER complex formation and RhoA/ROCK1 signal change. The regulatory role of Mg2+ on integrin α2-I domain–GXXGER complex formation in the above process was also investigated.MethodsThe zebrafish model of hypoxia-induced retinopathy was established, and OPTC-overexpressing plasmids were intravitreally injected to assess the antiangiogenesis effect of opticin. The regulatory role of opticin in integrin α2-I domain–GXXGER complex formation in vivo was analyzed by mass spectrometry. The mRNA and protein expression of RhoA/ROCK1 were examined. The concentration of Mg2+ as an activator of the integrin α2-I domain–GXXGER complex was measured. Solid-phase binding assays were performed to investigate the interference of opticin in integrin α2 collagen binding and the regulatory role of Mg2+ in that process.ResultsOpticin and OPTC-overexpressing plasmid injection reduced retinal neovascularization in the zebrafish model of hypoxia-induced retinopathy. Mass spectrometry revealed that opticin could inhibit integrin α2-I domain–GXXGER complex formation. The Mg2+ concentration was also decreased by opticin, which was another indication of the complex activation. Injection of OPTC-overexpressing plasmids inhibited mRNA and the protein expression of RhoA/ROCK1 in the zebrafish model of hypoxia-induced retinopathy. The solid-phase binding assay revealed that opticin could block integrin α2–collagen I binding in the presence of Mg2+.ConclusionsOpticin exerts its antiangiogenesis effect by interfering in the Mg2+-modulated integrin α2-I domain–collagen complex formation and suppressing the downstream RhoA/ ROCK1 signaling pathway.

Sesamin inhibits hypoxia-stimulated angiogenesis via the NF-κB p65/HIF-1α/VEGFA signaling pathway in human colorectal cancer.

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths. Tumor angiogenesis plays a critical role in CRC metastasis, and hypoxia, which widely existed in the tumor mass, drives tumor angiogenesis. Sesamin, a phytochemical derived from sesame seeds, has been reported to inhibit tumor cell growth and metastasis, however, the role of sesamin in CRC angiogenesis and its underlying mechanism have not been investigated yet. Here, an in vitro tube formation assay and an in vivo angiogenesis assay were used to explore the role of sesamin in CRC angiogenesis. In this study, we found that sesamin significantly inhibited hypoxia-stimulated CRC angiogenesis in a dose-dependent manner in vitro. Moreover, oral intake of sesamin dramatically suppressed neovessel formation of matrigel plugs with CRC cells in nude mice. In mechanism, sesamin reduced the expression of VEGFA to inhibit hypoxia-induced CRC angiogenesis. In addition, sesamin inhibited the phosphorylation of IκBα and thus restrained NF-κB p65 to activate HIF-1α transcription under hypoxic conditions. Finally, our results indicated that sesamin inhibited hypoxia-induced CRC angiogenesis via the NF-κB/HIF-1α/VEGFA signaling pathway. Our study might provide a theoretical and experimental basis for the use of sesamin in the prevention and treatment of CRC.

Prediction of immunotherapy efficacy and immunomodulatory role of hypoxia in colorectal cancer.

Immunotherapy has been used in the clinical treatment of colorectal cancer (CRC); however, most patients fail to achieve satisfactory survival benefits. Biomarkers with high specificity and sensitivity are being increasingly developed to predict the efficacy of CRC immunotherapy. In addition to DNA alteration markers, such as microsatellite instability/mismatch repair and tumor mutational burden, immune cell infiltration and immune checkpoints (ICs), epigenetic changes and no-coding RNA, and gut microbiomes all show potential predictive ability. Recently, the hypoxic tumor microenvironment (TME) has been identified as a key factor mediating CRC immune evasion and resistance to treatment. Hypoxia-inducible factor-1α is the central transcription factor in the hypoxia response that drives the expression of a vast number of survival genes by binding to the hypoxia response element in cancer and immune cells in the TME. Hypoxia regulates angiogenesis, immune cell infiltration and activation, expression of ICs, and secretion of various immune molecules in the TME and is closely associated with the immunotherapeutic efficacy of CRC. Currently, various agents targeting hypoxia have been found to improve the TME and enhance the efficacy of immunotherapy. We reviewed current markers commonly used in CRC to predict therapeutic efficacy and the mechanisms underlying hypoxia-induced angiogenesis and tumor immune evasion. Exploring the mechanisms by which hypoxia affects the TME will assist the discovery of new immunotherapeutic predictive biomarkers and development of more effective combinations of agents targeting hypoxia and immunotherapy.

Canagliflozin Modulates Hypoxia-Induced Metastasis, Angiogenesis and Glycolysis by Decreasing HIF-1α Protein Synthesis via AKT/mTOR Pathway.

The microenvironment plays a vital role in tumor progression, and hypoxia is a typical microenvironment feature in nearly all solid tumors. In this study, we focused on elucidating the effect of canagliflozin (CANA), a new class of antidiabetic agents, on hepatocarcinoma (HCC) tumorigenesis under hypoxia, and demonstrated that CANA could significantly inhibit hypoxia-induced metastasis, angiogenesis, and metabolic reprogramming in HCC. At the molecular level, this was accompanied by a reduction in VEGF expression level, as well as a reduction in the epithelial-to-mesenchymal transition (EMT)-related proteins and glycolysis-related proteins. Next, we focused our study particularly on the modulation of HIF-1α by CANA, which revealed that CANA decreased HIF-1α protein level by inhibiting its synthesis without affecting its proteasomal degradation. Furthermore, the AKT/mTOR pathway, which plays an important role in HIF-1α transcription and translation, was also inhibited by CANA. Thus, it can be concluded that CANA decreased metastasis, angiogenesis, and metabolic reprogramming in HCC by inhibiting HIF-1α protein accumulation, probably by targeting the AKT/mTOR pathway. Based on our results, we propose that CANA should be evaluated as a new treatment modality for liver cancer.

Co-delivery of photosensitizer and diclofenac through sequentially responsive bilirubin nanocarriers for combating hypoxic tumors

Considering that photodynamic therapy (PDT)-induced oxygen consumption and microvascular damage could exacerbate hypoxia to drive more glycolysis and angiogenesis, a novel approach to potentiate PDT and overcome the resistances of hypoxia is avidly needed. Herein, morpholine-modified PEGylated bilirubin was proposed to co-deliver chlorin e6, a photosensitizer, and diclofenac (Dc). In acidic milieu, the presence of morpholine could enable the nanocarriers to selectively accumulate in tumor cells, while PDT-generated reactive oxidative species (ROS) resulted in the collapse of bilirubin nanoparticles and rapid release of Dc. Combining with Dc showed a higher rate of apoptosis over PDT alone and simultaneously triggered a domino effect, including blocking the activity and expression of lactate dehydrogenase A (LDHA), interfering with lactate secretion, suppressing the activation of various angiogenic factors and thus obviating hypoxia-induced resistance-glycolysis and angiogenesis. In addition, inhibition of hypoxia-inducible factor-1α (HIF-1α) by Dc alleviated hypoxia-induced resistance. This study offered a sequentially responsive platform to achieve sufficient tumor enrichment, on-demand drug release and superior anti-tumor outcomes in vitro and in vivo.

CD146 as a promising therapeutic target for retinal and choroidal neovascularization diseases.

Blood vessel dysfunction causes several retinal diseases, including diabetic retinopathy, familial exudative vitreoretinopathy, macular degeneration and choroidal neovascularization in pathological myopia. Vascular endothelial growth factor (VEGF)-neutralizing proteins provide benefits in most of those diseases, yet unsolved haemorrhage and frequent intraocular injections still bothered patients. Here, we identified endothelial CD146 as a new target for retinal diseases. CD146 expression was activated in two ocular pathological angiogenesis models, a laser-induced choroid neovascularization model and an oxygen-induced retinopathy model. The absence of CD146 impaired hypoxia-induced cell migration and angiogenesis both in cell lines and animal model. Preventive or therapeutic treatment with anti-CD146 antibody AA98 significantly inhibited hypoxia-induced aberrant retinal angiogenesis in two retinal disease models. Mechanistically, under hypoxia condition, CD146 was involved in the activation of NFκB, Erk and Akt signalling pathways, which are partially independent of VEGF. Consistently, anti-CD146 therapy combined with anti-VEGF therapy showed enhanced impairment effect of hypoxia-induced angiogenesis in vitro and in vivo. Given the critical role of abnormal angiogenesis in retinal and choroidal diseases, our results provide novel insights into combinatorial therapy for neovascular fundus diseases.

Knockdown of m6A Reader IGF2BP3 Inhibited Hypoxia-Induced Cell Migration and Angiogenesis by Regulating Hypoxia Inducible Factor-1α in Stomach Cancer.

Hypoxia is a common feature of solid tumors including stomach cancer (SC) and is closely associated with cancer malignant progression. N6-methyladenosine (m6A), a common modification on RNA, is involved in the regulation of RNA fate and hypoxic responses in cancers. However, the interaction between m6A reader insulin-like growth factor-II mRNA-binding protein 3 (IGF2BP3) and SC hypoxic microenvironment is poorly defined. In the present study, expression levels of IGF2BP3 and hypoxia inducible factor-1α (HIF1A) were examined by bioinformatics analysis and RT-qPCR and western blot assays. Cell migratory ability was assessed through Transwell and wound healing assays. The angiogenic potential was evaluated by VEGF secretion, tube formation, and chick embryo chorioallantoic membrane (CAM) assays. The interaction between IGF2BP3 and HIF1A was explored using bioinformatics analysis and RIP and luciferase reporter assays. The results showed that IGF2BP3 and HIF1A were highly expressed in SC tissues and hypoxia-treated SC cells. IGF2BP3 knockdown inhibited hypoxia-induced cell migration and angiogenesis in SC. IGF2BP3 positively regulated HIF1A expression by directly binding to a specific m6A site in the coding region of HIF1A mRNA in SC cells. HIF1A overexpression abrogated the effects of IGF2BP3 knockdown on hypoxia-induced cell migration and angiogenesis in SC. In conclusion, IGF2BP3 knockdown inhibited hypoxia-induced cell migration and angiogenesis by down-regulating HIF1A in SC.

Notch‐1 and Notch‐3 Mediate Hypoxia‐Induced Activation of Synovial Fibroblasts in Rheumatoid Arthritis

To fully understand the molecular mechanism of hypoxia-induced rheumatoid arthritis synovial fibroblast cell (RASFC) activation via Notch-1 and Notch-3 signalling, and to evaluate its potential as a therapeutic target. Notch-1 and Notch-3 intracellular domain (N1ICD), Notch-3 intracellular domain (N3ICD), and hypoxia-inducible factor-1α (HIF-1α) were detected in RA synovial tissues via immunohistology. RASFC were cultured under hypoxic and normoxic conditions with or without small interfering RNAs, and N1ICD and N3ICD were overexpressed under normoxic conditions. Collagen-induced arthritis (CIA) rats were administered with LY411575 (inhibition of N1ICD and N3ICD) for 15 and 28 days, and its therapeutic efficacy was assessed by histology, radilology and inflammatory cytokine detection. In the study, we found that N1ICD, N3ICD and HIF-1α were abundantly expressed in RA patient synovial tissues. Meanwhile, HIF-1α was found to directly regulate the expression of Notch-1 and Notch-3 genes under hypoxic conditions. Moreover, hypoxia induced N1ICD and N3ICD expression in RASFC was blocked by HIF-1α small interfering RNA (siHIF-1α).Notch-1 small interfering RNA (siNotch-1) and Notch-3 small interfering RNA (siNotch-3) inhibited hypoxia-induced RASFC invasion and angiogenesis in vitro, whereas N1ICD and N3ICD overexpression promoted these processes. In addition, it was revealed that Notch-1 regulates RASFC migration and epithelial-mesenchymal transition (EMT) under hypoxia, whereas Notch-3 regulates anti-apoptosis and autophagy. Further, in vivo studies showed that N1ICD and N3ICD inhibitor LY411575 had a therapeutic effect on CIA rats. Collectively, this study has identified a functional link between HIF-1α, Notch-1, and Notch-3 signalling in regulating RASFC activation and rheumatoid arthritis.

Effect of PACAP on Hypoxia-Induced Angiogenesis and Epithelial-Mesenchymal Transition in Glioblastoma.

Pituitary adenylate cyclase-activating polypeptide (PACAP) exerts different effects in various human cancer. In glioblastoma (GBM), PACAP has been shown to interfere with the hypoxic micro-environment through the modulation of hypoxia-inducible factors via PI3K/AKT and MAPK/ERK pathways inhibition. Considering that hypoxic tumor micro-environment is strictly linked to angiogenesis and Epithelial–Mesenchymal transition (EMT), in the present study, we have investigated the ability of PACAP to regulate these events. Results have demonstrated that PACAP and its related receptor, PAC1R, are expressed in hypoxic area of human GBM colocalizing either in epithelial or mesenchymal cells. By using an in vitro model of GBM cells, we have observed that PACAP interferes with hypoxic/angiogenic pathway by reducing vascular-endothelial growth factor (VEGF) release and inhibiting formation of vessel-like structures in H5V endothelial cells cultured with GBM-conditioned medium. Moreover, PACAP treatment decreased the expression of mesenchymal markers such as vimentin, matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9) as well as CD44 in GBM cells by affecting their invasiveness. In conclusion, our study provides new insights regarding the multimodal role of PACAP in GBM malignancy.

The anti-dysenteric drug fraxetin enhances anti-tumor efficacy of gemcitabine and suppresses pancreatic cancer development by antagonizing STAT3 activation.

Fraxetin, a natural product isolated and purified from the bark of Fraxinus bungeana A.DC., has anti-inflammatory, analgesic, and anti-dysenteric activities. This study aimed to investigate the anti-tumor effects of fraxetin in pancreatic ductal adenocarcinoma (PDA). The effects of fraxetin on the malignant biological behavior of PDA were evaluated. Besides, the effects of fraxetin on the sensitivity of PCCs to gemcitabine, angiogenesis, the epithelial-mesenchymal transition (EMT), glucose metabolism, reactive oxygen species (ROS), and STAT3 activity were analyzed. By reversing the EMT, fraxetin suppressed proliferation, invasion, and migration, and induced mitochondrial-dependent apoptosis in PCCs. Also, treatment with fraxetin inhibited PDA growth and metastasis in nude mouse models. Furthermore, fraxetin made PCCs more sensitive to the chemotherapy drug gemcitabine. Mechanically, fraxetin treatment suppressed oncogenic KRAS-triggered STAT3 activation in PCCs and PDA tissues. Fraxetin shows significant interactions with STAT3 Src Homology 2 (SH2) domain residues, thereby preventing its homo-dimer formation, which then blocks the activation of downstream signal pathways. The anti-tumor activity of fraxetin in PDA was functionally rescued by a STAT3 activator colivelin. As a result, fraxetin hindered hypoxia-induced angiogenesis by decreasing HIF-1α and VEGFA expression, controlled glucose metabolism by reducing GLUT1 expression, inhibited the EMT by blocking the Slug-E-cadherin axis, and drove ROS-mediated apoptosis by regulating the STAT3-Ref1 axis. In conclusion, fraxetin enhances the anti-tumor activity of gemcitabine and suppresses pancreatic cancer development by antagonizing STAT3 activation.

The role of anlotinib-mediated EGFR blockade in a positive feedback loop of CXCL11-EGF-EGFR signalling in anaplastic thyroid cancer angiogenesis.

Hypoxia-induced angiogenesis functions importantly in anaplastic thyroid cancer (ATC) progression. However, the therapeutic potential of broad-spectrum anti-angiogenic agent remains undefined. Anlotinib conventionally targets VEGFR, FGFR and PDGFR. Here, a novel role of anlotinib on ATC angiogenesis was illustrated. Molecular expressions were established via tissue microarray. Multiple assays (tubule formation, 3D sprouting and chicken chorioallantoic membrane model) were used for angiogenic evaluation. Panels of molecular screening were achieved by antibody and PCR arrays. The loop binding motif of EGFR for homology modelling was prepared using Maestro. Anlotinib could dose- and time-dependently inhibit cell viability under normoxia and hypoxia and could repress hypoxia-activated angiogenesis more efficiently in vitro and in vivo. CXCL11 and phospho-EGFR were hypoxia-upregulated with a positive correlation. The cancer-endothelium crosstalk could be mediated by the positive CXCL11-EGF-EGFR feedback loop, which could be blocked by anlotinib directly targeting EGFR via a dual mechanism by simultaneous inhibitory effects on cancer and endothelial cells. The AKT-mTOR pathway was involved in this regulatory network. The newly identified CXCL11-EGF-EGFR signalling provided mechanistic insight into the interaction between cancer and endothelial cells under hypoxia, and EGFR was a novel target. Anlotinib may be the encouraging therapeutic candidate in ATC.

A narrative review of research progress on the relationship between hypoxia-inducible factor-2α and wound angiogenesis.

This article aims to pay attention to the latest research on the expression, activation and function of hypoxia-inducible factor-2α (HIF-2α) under hypoxia and non-hypoxia conditions, and summarizes the current knowledge about the interaction between hypoxia-inducible factor-2 and angiogenesis, hoping to understand its actions in physiology and disease, with the goal of providing a new strategy for the diagnosis and treatment of wounds. Wound healing is a complex and continuous process, involving coagulation, inflammation, angiogenesis, new tissue formation and extracellular matrix remodeling. Of these, angiogenesis is an essential step. One of the main reasons for non-healing or delayed healing of wounds in peripheral vascular diseases and diabetes is the reduced ability to regenerate microvessels through the process of angiogenesis, which has become the focus of new methods for treating chronic wounds. HIF-2α regulates many aspects of angiogenesis, including vascular maturation, cell migration, proliferation and metastasis. Throughout extensive search of PubMed, summarize the medical research on HIF-2α to 2020. HIF-2α is necessary for normal embryonic development by stimulating the expression of angiogenic factors, such as vascular endothelial growth factor (VEGF). It is essential for the formation of new blood vessels in physiological and pathophysiological environments. Targeting HIF-2α in wound healing has much clinical significance for tissue repair.

PSF functions as a repressor of hypoxia-induced angiogenesis by promoting mitochondrial function

BackgroundAbnormal neovascularization is the most common cause of blindness, and hypoxia alters tissue metabolism, function, and morphology. HIF-1α, the transcriptional activator of VEGF, has intricate mechanisms of nuclear translocation and activation, but its signal termination mechanisms remain unclear.MethodsWe investigated the role of polypyrimidine tract-binding protein-associated splicing factor (PSF) in cellular energy production, migration, and proliferation by targeting HIF-1α in vivo and in vitro PSF plasmids were transfected with liposome 2000 transfection reagent. Young C57/BL6J mice were kept in a hyperoxia environment, followed by indoor air, resulting in oxygen-induced retinopathy. Oxygen-induced retinopathy (OIR) animals were randomly divided into three groups: OIR group, OIR + vector group (OIR cubs treated with rAAV vector) and OIR + PSF group (OIR cubs treated with rAAV-PSF). Age-matched C57/BL6J mice were used as controls and exposed to constant normoxic conditions. The animals were executed and their pupils were subjected to subsequent experiments. The metabolic spectrum was analyzed by Seahorse XFe96 flux analyzer, and OCR and extracellular acidification rate were quantified at the same time.ResultsPSF ameliorated retinal neovascularization and corrected abnormal VEGF expression in mice with oxygen-induced retinopathy and reduced intra-retinal neovascularization in Vldlr − / − mice. PSF reprogrammed mitochondrial bioenergetics and inhibited the transition of endothelial cells after hypoxia, suggesting its involvement in pathological angiogenesis.Ectopic PSF expression inhibited hypoxia-induced HIF-1α activation in the nucleus by recruiting Hakai to the PSF/HIF-1α complex, causing HIF-1α inhibition. PSF knockdown increased hypoxia-stimulated HIF-1α reactions. These hypoxia-dependent processes may play a vital role in cell metabolism, migration, and proliferation. Thus, PSF is a potential treatment target in neovascularization-associated ophthalmopathy.ConclusionThis is the first study showing that PSF inhibits HIF-1α via recruitment of Hakai, modulates mitochondrial oxidation and glycolysis, and downregulates VEGF expression under hypoxia. We propose a new HIF-1 α/Hakai regulatory mechanism that may play a vital role in the pathogenesis of neovascularization in ophthalmopathy.PSF-Hakai–HIF-1α signaling pathway under hypoxia condition. Schematic diagram showing that the PSF-Hakai–HIF-1α signaling pathway. Under hypoxia condition, PSF-Hakai complex regulate HIF-1α signaling, thus inhibiting downstream target gene VEGF, cell metabolism and angiogenesis eventually.Bpb6gLDdM8K1hTjkEP-G9vVideo : Detailed information of Materials and Methods.

Effect and Molecular Mechanisms of Jiedu Recipe on Hypoxia-Induced Angiogenesis after Transcatheter Arterial Chemoembolization in Hepatocellular Carcinoma.

Transcatheter arterial chemoembolization (TACE) is one of the effective treatment methods for hepatocellular carcinoma (HCC) in middle and late phases. However, TACE-induced hypoxia may promote the angiogenesis and section of some cytokines, such as IL-8, and, thereby, lead to tumor metastasis. Therefore, we investigated the effect of Jiedu Recipe (JR), which has been demonstrated as an effective Traditional Chinese Medicine (TCM) recipe on HCC, on TACE-induced cytokines upregulation and hypoxia-induced angiogenesis. A total of 88 hepatocellular carcinoma (HCC) patients treated with TACE were enrolled and divided into a JR group or control group. TACE induced significant increases of neutrophil lymphocyte ratio (NLR), platelet lymphocyte ratio (PLR), IL-1β, IL-2R, IL-6, and IL-8. JR treatment significantly inhibited the elevation of IL-8 compared with control. In vitro, JR significantly inhibited the hypoxia-induced overexpression of IL-8, HIF-1α, and VEGF mRNA in Huh 7 cells. ELISA assay demonstrated the effect of JR on IL-8 expression. Both hypoxia and IL-8 may promote angiogenesis which was suppressed by JR. Western blot showed that IL-8 upregulated the expression of phosphorylation of AKT, ERK, NF-κB, and VEGFR, which were inhibited by JR. On the other hand, effects of IL-8 on the increase of p-AKT and p-ERK were also blocked by LY294002 and U0126, respectively. In conclusion, our results indicated that JR may inhibit hypoxia-induced angiogenesis through suppressing IL-8/HIF-1α/PI3K and MAPK/ERK pathways after TACE in HCC patients.

PlGF knockdown attenuates hypoxia-induced stimulation of cell proliferation and glycolysis of lung adenocarcinoma through inhibiting Wnt/\u03b2-catenin pathway

BackgroundAngiogenic placental growth factor (PlGF) plays a role in hypoxia-induced angiogenesis. Here, we aimed to investigate the biological roles of PlGF in cell proliferation and glycolysis of lung adenocarcinoma (LUAD) and the underlying molecular mechanisms.MethodsPlGF was knocked down in H358 and H1975 cells by lentiviruses, which were then cultured under hypoxia (90% N2, 5%CO2 and 5%O2) for 24 h. PlGF was overexpressed in PC9 cells treated with XAV939, inhibitor of Wnt/β-catenin signaling pathway. PlGF-silencing H1975 cells were implanted into mice, and tumor xenografts were harvested and analyzed.ResultsHypoxia treatment led to up-regulation of PlGF, C-myc, lactate dehydrogenase A (LDHA), and β-catenin, promotion of cell proliferation and glycolysis in H358 and H1975 cells, which were obviously reversed by knocking down PlGF. In tumors, PlGF knockdown significantly prohibited cell proliferation and glycolysis, and decreased expression of C-myc, LDHA, and β-catenin. PlGF overexpression markedly strengthened cell proliferation, which was inhibited by β-catenin knockdown. Consistently, XAV939, inhibitor of Wnt/β-catenin pathway, also inhibited PlGF-induced cell proliferation, glycolysis, and β-catenin expression in PC9 cells.ConclusionPlGF knockdown inhibited the stimulatory effect of hypoxia on cell proliferation and glycolysis of LUAD through deactivating Wnt/β-catenin pathway.

Asparagus Polysaccharide inhibits the Hypoxia-induced migration, invasion and angiogenesis of Hepatocellular Carcinoma Cells partly through regulating HIF1α/VEGF expression via MAPK and PI3K signaling pathway.

Aim: Although there are so many treatment strategies used for hepatocellular carcinoma (HCC), the overall survival (OS) of HCC patients still remains very low. In our previous studies, asparagus polysaccharide (ASP) has been demonstrated to suppress proliferation, migration, invasion and angiogenesis of HCC cells under normoxic conditions in vitro. However, the inhibitory effects of ASP on the hypoxia-induced migration, invasion and angiogenesis of HCC cells still remain largely unexplored.Materials and methods: Cell Counting Kit-8 (CCK-8) assay, transwell assay, and tube formation assay were used to determine the effects of ASP on hypoxia-induced proliferation, migration, invasion and angiogenesis of HCC cells. ELISA, Western blotting analysis and immunofluorescence assay were used to confirm the effects of ASP on the expressions of HIF-1α and VEGF at the protein level. Moreover, effects of ASP on signaling pathway-related proteins were investigated by Western blotting analysis. Immunohistochemistry (IHC) assay was applied to test the effects of ASP on angiogenesis-associated proteins of tumor cells.Results: We showed that ASP effectively suppressed hypoxia-induced proliferation, migration, invasion and angiogenesis of SK-Hep1 and Hep-3B cells in a dose-dependent manner. In addition, the inhibitory effect of ASP might be partly attributed to down-regulation of HIF1α and VEGF proteins in SK-Hep1 and Hep-3B cells under hypoxic conditions. Moreover, signaling pathway study indicated that ASP significantly down-regulated the hypoxia-induced expressions of p-AKT, p-mTOR and p-ERK, while it had little effects on AKT, mTOR and ERK. Besides, SK-Hep1 xenograft tumor models in nude mice further confirmed that the inhibitory effect of ASP on xenograft tumors might be exerted partly via down-regulation of HIF1α and VEGF through blocking MAPK and PI3K signaling pathways.Conclusions: Our findings suggested that ASP suppressed the hypoxia-induced migration, invasion and angiogenesis of HCC cells partly through regulating HIF-1α/VEGF expression via MAPK and PI3K signaling pathways.

Environmental Enrichment Improved Cognitive Performance in Mice under Normoxia and Hypoxia.

The mammalian brain modulates its microvascular network to accommodate tissue energy demand in a process referred to as angioplasticity. There is an aging effect on cognitive function and adaptive responses to hypoxia. Hypoxia-induced angiogenesis is delayed in the aging mouse brain. Additionally, it has been shown that environmental enrichment provides an environment that fosters increased physical activity and sensory stimulation for mice as compared to standard housing; this stimulation increases neuronal activity and consequently brain oxygen demand. In this study, we investigated the effect of environmental enrichment and chronic hypoxia on cognitive performance in the young (2-4months old) and the aged mice (17-21months old). Mice were placed in a non-enriched or an enriched environment for 4weeks under normoxia followed by 3weeks of hypobaric hypoxia (~0.4atm, equivalent to 8% normobaric oxygen at sea level). Cognitive function was evaluated using the Y-maze and the novel object recognition tests in the enriched or non-enriched mice under normoxic or hypoxic conditions. In Y-maze, a high alternation rate is indicative of sustained cognition as the animals must remember which arm was entered last, so as not to re-enter it. Novel object recognition is based on the natural tendency of rodents to investigate a novel object instead of a familiar one; a higher novel object exploration rate is indicative of better cognitive function. The young mice showed a significantly higher alternation rate (%, 63±7 vs. 48±10, n=8 and 10, respectively) in the Y-Maze test as compared to the aged mice. Under normoxia, the enriched mice showed an improved alternation rate (%, 63±10, n=10) in Y-Maze test and a higher novel object exploration rate (%, 68±10 vs. 52±10) compared to the non-enriched controls. Similar results were observed for both young and aged mice following hypoxic exposure. Our data suggests that environmental enrichment improved the cognitive performance in the young and aged mice under normoxic and hypoxic conditions.

Hypoxia-induced Angiogenesis Rescues Survival from Small for Size Syndrome (SFSS)

After extended hepatectomy, hepatocyte proliferation proceeds sinusoidal endothelial cell (SEC) remodeling causing a transient perturbation of the lobular architecture with proliferating hepatocytes forming avascular, hypoxic, clusters. Hypoxia is, thus, considered at the origin of liver dysfunction in SFSS-hepatectomy. Recently, we showed that activation of hypoxia sensors in an upfront SFSS-hepatectomy surged an early angiogenic switch and preserved the sinusoidal architecture with a favorable impact on survival. Aim: to decipher the role hypoxia-induced angiogenesis in SFSS-setting hepatectomy. Methods: we developed a mouse model of SFSS-hepatectomy (PHx-80%) and used PHx-70% as controls. SFSS-hepatectomy mice were submitted to normoxia (inspired oxygen fraction-FiO2: 21%), local hypoxia (hepatic artery ligation (PHx-HAL)), and systemic hypoxia by placing the animals in hypoxic chambers (FiO2: 11%, PHx-HC). We assessed mortality, hepatocyte and liver SEC proliferation. Results: Compared to PHx-70%, PHx-80% showed high mortality rates (68% on postoperative day (POD) 7 (p=0,002)). Hepatocyte proliferation on POD 3 was higher in PHx-80% (p=0,03), while SEC proliferation did not differ, suggesting an amplified disorganization of the regenerating lobule in SFSS-hepatectomy. Compared to normoxic PHx-80%, PHx-HAL tended to have a favorable impact on survival (75% on POD3), while animals subjected to SFSS- hepatectomy and placed into hypoxic chambers showed improved survival (p=0,0007). Hepatocyte proliferation was similar between the hypoxic and normoxic SFSS-liver remnants. However, local and systemic hypoxia significantly triggered early angiogenesis. Conclusions: The current data suggest that hypoxia rescues survival from SFSS. By balancing angiogenesis with hepatocyte proliferation, hypoxia restores the lobular liver architecture allowing an efficient regeneration after major hepatectomy.

Phosphorylation of seryl-tRNA synthetase by ATM/ATR is essential for hypoxia-induced angiogenesis.

Hypoxia-induced angiogenesis maintains tissue oxygen supply and protects against ischemia but also enhances tumor progression and malignancy. This is mediated through activation of transcription factors like hypoxia-inducible factor 1 (HIF-1) and c-Myc, yet the impact of hypoxia on negative regulators of angiogenesis is unknown. During vascular development, seryl-tRNA synthetase (SerRS) regulates angiogenesis through a novel mechanism by counteracting c-Myc and transcriptionally repressing vascular endothelial growth factor A (VEGFA) expression. Here, we reveal that the transcriptional repressor role of SerRS is inactivated under hypoxia through phosphorylation by ataxia telangiectasia mutated (ATM) and ataxia telangiectasia mutated and RAD3-related (ATR) at Ser101 and Ser241 to attenuate its DNA binding capacity. In zebrafish, SerRSS101D/S241D, a phosphorylation-mimicry mutant, cannot suppress VEGFA expression to support normal vascular development. Moreover, expression of SerRSS101A/S241A, a phosphorylation-deficient and constitutively active mutant, prevents hypoxia-induced binding of c-Myc and HIF-1 to the VEGFA promoter, and activation of VEGFA expression. Consistently, SerRSS101A/S241A strongly inhibits normal and tumor-derived angiogenesis in mice. Therefore, we reveal a key step regulating hypoxic angiogenesis and highlight the importance of nuclear SerRS in post-developmental angiogenesis regulation in addition to vascular development. The role of nuclear SerRS in inhibiting both c-Myc and HIF-1 may provide therapeutic opportunities to correct dysregulation of angiogenesis in pathological settings.

Withdrawn: Long noncoding RNA XIST participates hypoxia-induced angiogenesis in human brain microvascular endothelial cells through regulating miR 485/SOX7 axis.

Withdrawal: Hu C, Bai X, Liu C, Hu Z. Long noncoding RNA XIST participates hypoxia-induced angiogenesis in human brain microvascular endothelial cells through regulating miR-485/SOX7 axis. Microcirculation. 2019 (https://doi.org/10.1111/micc.12601) The above article, published online on 29 November 2019 in Wiley Online Library (wileyonlinelibrary.com), has been withdrawn at the request of the authors. The withdrawal has been agreed by the journal Editor in Chief Donald Welsh, and by John Wiley & Sons Ltd. due to major overlap with a previously published article from the same group of authors.