Placenta growth factor-induced early growth response 1 (Egr-1) regulates hypoxia-inducible factor-1alpha (HIF-1alpha) in endothelial cells

The cytokine trio - visfatin, placental growth factor and fractalkine - and their role in myocardial infarction with non-obstructive coronary arteries (MINOCA)

Myocardial infarction with nonobstructive coronary arteries (MINOCA) remains a puzzling clinical entity. It is characterized by clinical evidence of myocardial infarction (MI) with normal or near-normal coronary arteries in angiography. Given the complex etiology including multiple possible scenarios with varied pathogenetic mechanisms, profound investigation of the plausible biomarkers of MINOCA may bring further pathophysiological insights and novel diagnostic opportunities. Cytokines have a great diagnostic potential and are used as biomarkers for many diseases. An unusual trio of visfatin, placental growth factor (PlGF) and fractalkine (CX3CL1) can directly promote vascular dysfunction, inflammation and angiogenesis through the activation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling. They are redundant in physiological processes and become overexpressed in the pathomechanisms underlying MINOCA. The knowledge about their concentration might serve as a valuable diagnostic and/or therapeutic tool for assessing vascular endothelial function. Here we analyze the current knowledge on visfatin, PlGF and CX3CL1 in the context of MINOCA and present the novel clinical implications of their combined expression as predictors or indicators of this condition.

Biomolecules Involved in Both Metastasis and Placenta Accreta Spectrum-Does the Common Pathophysiological Pathway Exist?

The process of epithelial-to-mesenchymal transition (EMT) is crucial in the implantation of the blastocyst and subsequent placental development. The trophoblast, consisting of villous and extravillous zones, plays different roles in these processes. Pathological states, such as placenta accreta spectrum (PAS), can arise due to dysfunction of the trophoblast or defective decidualization, leading to maternal and fetal morbidity and mortality. Studies have drawn parallels between placentation and carcinogenesis, with both processes involving EMT and the establishment of a microenvironment that facilitates invasion and infiltration. This article presents a review of molecular biomarkers involved in both the microenvironment of tumors and placental cells, including placental growth factor (PlGF), vascular endothelial growth factor (VEGF), E-cadherin (CDH1), laminin γ2 (LAMC2), the zinc finger E-box-binding homeobox (ZEB) proteins, αVβ3 integrin, transforming growth factor β (TGF-β), β-catenin, cofilin-1 (CFL-1), and interleukin-35 (IL-35). Understanding the similarities and differences in these processes may provide insights into the development of therapeutic options for both PAS and metastatic cancer.

VALPROIC ACID INHIBITS CLASSICAL MONOCYTE-DERIVED TISSUE FACTOR AND ALLEVIATES HEMORRHAGIC SHOCK-INDUCED ACUTE LUNG INJURY IN RATS

ABSTRACT

Background: Monocytes and monocyte-derived tissue factor (TF) promote the development of sepsis-induced acute lung injury (ALI). Classical monocytes (C-Mcs) can be induced to express TF. Valproic acid (VPA) alleviates hemorrhagic shock (HS)-induced ALI (HS/ALI) and inhibits TF expression in monocytes. We hypothesized that C-Mcs and C-Mc-derived TF promoted HS/ALI and that VPA could inhibit C-Mc-derived TF expression and attenuate HS/ALI. Methods: Wistar rats and THP-1 cells were used to evaluate our hypothesis. Monocyte subtypes were analyzed by flow cytometry; mRNA expression was measured by fluorescence quantitative polymerase chain reaction; protein expression was measured by Western blotting, immunofluorescence, or immunohistology; inflammatory cytokines levels were measured by enzyme-linked immunosorbent assay; and ALI scores were used to determine the degree of ALI. Results: The blood %C-Mcs and C-Mcs/non-C-Mcs ratios, monocyte TF levels, serum and/or lung inflammatory cytokine levels, and ALI scores of HS rats were significantly increased ( P < 0.05). After monocyte depletion and thrombin inhibition, the inflammatory cytokine levels and ALI scores were significantly decreased ( P < 0.05). VPA reduced the %C-Mcs and C-Mc/non-C-Mc ratios, TF expression, inflammatory cytokine levels, and ALI scores during HS ( P < 0.05) and inhibited HS-induced monocyte Egr-1 and p-ERK1/2 expression ( P < 0.05). VPA inhibited hypoxia-induced TF expression in THP-1 cells by regulating the p-ERK1/2-Egr-1 axis. Conclusion: C-Mcs and C-Mc-derived TF accelerate the development of HS/ALI by increasing thrombin production. VPA inhibits HS-induced C-Mc production of TF by regulating the p-ERK1/2-Egr-1 axis and alleviates HS/ALI.

Tracing the cis-regulatory changes underlying the endometrial control of placental invasion

Among eutherian (placental) mammals, placental embedding into the maternal endometrium exhibits great differences, from being deeply invasive (e.g., humans) to noninvasive (e.g., cattle). The degree of invasion of placental trophoblasts is positively correlated with the rate of cancer malignancy. Previously, we have shown that fibroblasts from different species offer different levels of resistance to the invading trophoblasts as well as to cancer cell invasion. Here we present a comparative genomic investigation revealing cis-regulatory elements underlying these interspecies differences in invasibility. We identify transcription factors that regulate proinvasibility and antiinvasibility genes in stromal cells. Using an in vitro invasibility assay combined with CRISPR-Cas9 gene knockout, we found that the transcription factors GATA2 and TFDP1 strongly influence the invasibility of endometrial and skin fibroblasts. This work identifies genomic mechanisms explaining species differences in stromal invasibility, paving the way to therapies targeting stromal characteristics to regulate placental invasion, wound healing, and cancer dissemination.

Placental growth factor and Fms related tyrosine kinase-1 are hypomethylated in preeclampsia placentae

Aim: This study aims to examine the DNA methylation (DNAm) and expression patterns of genes associated with placental angiogenesis in preeclampsia. Materials & methods: DNAm and expression were examined in normotensive (n = 100) and preeclampsia (n = 100) women using pyrosequencing and quantitative real-time PCR respectively. Results: Hypomethylation at several CpGs was observed in PlGF and FLT-1 in women with preeclampsia compared to normotensive controls. PlGF expression was lower in women with preeclampsia while FLT-1 expression was comparable. DNAm at various CpGs was negatively correlated with expression in both the genes and were associated with maternal blood pressure and birth outcomes. Conclusion: DNAm and expression of angiogenic factors in placentae are differentially regulated in preeclampsia and influence birth outcomes.

Intracellular Delivery by Membrane Disruption: Mechanisms, Strategies, and Concepts

Intracellular delivery is a key step in biological research and has enabled decades of biomedical discoveries. It is also becoming increasingly important in industrial and medical applications ranging from biomanufacture to cell-based therapies. Here, we review techniques for membrane disruption-based intracellular delivery from 1911 until the present. These methods achieve rapid, direct, and universal delivery of almost any cargo molecule or material that can be dispersed in solution. We start by covering the motivations for intracellular delivery and the challenges associated with the different cargo types-small molecules, proteins/peptides, nucleic acids, synthetic nanomaterials, and large cargo. The review then presents a broad comparison of delivery strategies followed by an analysis of membrane disruption mechanisms and the biology of the cell response. We cover mechanical, electrical, thermal, optical, and chemical strategies of membrane disruption with a particular emphasis on their applications and challenges to implementation. Throughout, we highlight specific mechanisms of membrane disruption and suggest areas in need of further experimentation. We hope the concepts discussed in our review inspire scientists and engineers with further ideas to improve intracellular delivery.

SINHCAF/FAM60A and SIN3A specifically repress HIF-2α expression

The SIN3A-HDAC (histone deacetylase) complex is a master transcriptional repressor, required for development but often deregulated in disease. Here, we report that the recently identified new component of this complex, SINHCAF (SIN3A and HDAC-associated factor)/FAM60A (family of homology 60A), links the SIN3A-HDAC co-repressor complex function to the hypoxia response. We show that SINHCAF specifically represses HIF-2α mRNA and protein expression, via its interaction with the transcription factor SP1 (specificity protein 1) and recruitment of HDAC1 to the HIF-2α promoter. SINHCAF control over HIF-2α results in functional cellular changes in in vitro angiogenesis and viability. Our analysis reveals an unexpected link between SINHCAF and the regulation of the hypoxia response.

PlGF and sFlt-1 levels in patients with non-transfusion-dependent thalassemia: Correlations with markers of iron burden and endothelial dysfunction

BACKGROUND

Levels of the angiogenic cytokines placental growth factor (PlGF) and soluble Fms-like tyrosine kinase-1 (sFlt-1) and the angiogenic balance, expressed by sFlt-1/PlGF ratio, are perturbed in sickle-cell disease and iron overload, but they have not been evaluated in non-transfusion-dependent thalassemia (NTDT).

PATIENTS AND METHODS

We measured levels of PlGF, sFlt-1 and vWF:antigen in patients with NTDT of beta-thalassemia genotype, and correlated them with erythrocytic indices and markers of iron overload, inflammation, and tissue hypoxia. Thirty-four NTDT patients with mean hemoglobin level of 8.4 g/dL were included in the study along with 20 apparently healthy individuals who served as controls.

RESULTS

Ferritin, LDH, and hs-CRP were higher in patients as compared to controls. We found significant differences between patients and controls in regard to levels of PlGF (52.2 vs 17.2 pg/mL, P < .001), sFlt-1/PlGF (2 vs 4.7, P < .001), and vWF:antigen (88 vs 77.1 IU/dL, P < .01). There was a strong correlation of ferritin with PlGF (r = .653, P < .001) and with vWF:antigen (r = .503, P = .003).

CONCLUSIONS

In this study, we demonstrated an association between increased PlGF and iron overload and the degree of tissue hypoxia in patients with NTDT. High vWF:antigen expressing endothelial damage may be associated with specific NTDT comorbidities.

Cigarette smoke extract induces placental growth factor release from human bronchial epithelial cells via ROS/MAPK (ERK-1/2)/Egr-1 axis

Etiological evidence demonstrates that there is a significant association between cigarette smoking and chronic airway inflammatory disease. Abnormal expression of placental growth factor (PlGF) has been reported in COPD, and its downstream signaling molecules have been reported to contribute to the pathogenesis of airway epithelial cell apoptosis and emphysema. However, the signaling mechanisms underlying cigarette smoke extract (CSE)-induced PlGF expression in airway microenvironment remain unclear. Herein, we investigated the effects of reactive oxygen species (ROS)-dependent activation of the mitogen-activated protein kinase (MAPK) (extracellular signal-regulated kinase1/2 [ERK-1/2])/early growth response-1 (Egr-1) pathway on CSE-induced PlGF upregulation in human bronchial epithelium (HBE). The data obtained with quantitative reverse transcription polymerase chain reaction, Western blot, enzyme-linked immunosorbent assay (ELISA) and immunofluorescence staining analyses showed that CSE-induced Egr-1 activation was mainly mediated through production of ROS and activation of the MAPK (ERK-1/2) cascade. The binding of Egr-1 to the PlGF promoter was corroborated by an ELISA-based DNA binding activity assay. These results demonstrate that ROS activation of the MAPK (ERK-1/2)/Egr-1 pathway is a main player in the regulatory mechanism for CSE-induced PlGF production and that the use of an antioxidant could partly abolish these effects. Understanding the mechanisms of PlGF upregulation by CSE in the airway microenvironment may provide rational therapeutic interventions for cigarette smoking-related airway inflammatory diseases.

Iodine Affects Differentiation and Migration Process in Trophoblastic Cells

Iodine deficiency is associated with oxidative stress increase and preeclampsia during gestation, suggesting that iodine concentration plays an important role in the normal placenta physiology. The question raised is to analyze the effect of iodine deficiency on oxidative stress, viability, differentiation, and migration process and changes in the expression of differentiation and migration markers. Iodine deprivation was done using potassium perchlorate (KCLO4) to block sodium iodide symporter (NIS) transporter and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid DIDS to inhibit pendrine (PEN) transport for 3-48 h. Then trophoblast cells were treated with low iodine doses of 5-500 μM and high iodine doses of 100-5000 μM. Oxidative stress, viability, and human chorionic gonadotropin (hGC) were measured by colorimetric methods. Migration throphoblast cells were evaluated by both wound healing and Boyden chamber assays. Changes in mRNA expression were analyzed by real-time RT-PCR. Iodine deprivation induces a significant increase of reactive oxygen species (ROS), viability, and migration process vs control cells. We found a significant overregulation in the mRNA's peroxisome proliferator-activated receptor (PPAR-gamma), Snail, and matrix metalloproteinase-9 (MMP-9) mRNA's in cells deprived of iodine, as well as a down glial cell missing-1 (GCM-1) regulation, hGC, pregnancy-associated plasma protein-A (PAPP-A), and E-cadherin mRNA expression. The expression of hypoxic induction factor alpha (HIFα) mRNA does not change with iodine deprivation. In cells deprived of iodine, supplementing low iodine doses (5-500 μM) does not induce any significant changes in viability. However, ROS and migration process were decreased, although we found an increased human chorionic gonadotropin (hCG) secretion as a differentiation marker. In addition, we found that PPAR-gamma, Snail, and MPP-9 mRNAs expression are downregulated with low iodine doses, in contrast with GCM-1, PAPP-A, hGC, and E-cadherin that increase their expression vs cells deprived of iodine. High iodine doses (1000-5000 μM) have shown cytotoxic effects. Based on our results, iodine is important for keeping the proliferation/differentiation balance in the placenta.

Genetic recapitulation of human pre-eclampsia risk during convergent evolution of reduced placental invasiveness in eutherian mammals

The relationship between phenotypic variation arising through individual development and phenotypic variation arising through diversification of species has long been a central question in evolutionary biology. Among humans, reduced placental invasion into endometrial tissues is associated with diseases of pregnancy, especially pre-eclampsia, and reduced placental invasiveness has also evolved, convergently, in at least 10 lineages of eutherian mammals. We tested the hypothesis that a common genetic basis underlies both reduced placental invasion arising through a developmental process in human placental disease and reduced placental invasion found as a derived trait in the diversification of Euarchontoglires (rodents, lagomorphs, tree shrews, colugos and primates). Based on whole-genome analyses across 18 taxa, we identified 1254 genes as having evolved adaptively across all three lineages exhibiting independent evolutionary transitions towards reduced placental invasion. These genes showed strong evidence of enrichment for associations with pre-eclampsia, based on genetic-association studies, gene-expression analyses and gene ontology. We further used in silico prediction to identify a subset of 199 genes that are likely targets of natural selection during transitions in placental invasiveness and which are predicted to also underlie human placental disorders. Our results indicate that abnormal ontogenies can recapitulate major phylogenetic shifts in mammalian evolution, identify new candidate genes for involvement in pre-eclampsia, imply that study of species with less-invasive placentation will provide useful insights into the regulation of placental invasion and pre-eclampsia, and recommend a novel comparative functional-evolutionary approach to the study of genetically based human disease and mammalian diversification.

Placenta growth factor augments airway hyperresponsiveness via leukotrienes and IL-13

Airway hyperresponsiveness (AHR) affects 55%-77% of children with sickle cell disease (SCD) and occurs even in the absence of asthma. While asthma increases SCD morbidity and mortality, the mechanisms underlying the high AHR prevalence in a hemoglobinopathy remain unknown. We hypothesized that placenta growth factor (PlGF), an erythroblast-secreted factor that is elevated in SCD, mediates AHR. In allergen-exposed mice, loss of Plgf dampened AHR, reduced inflammation and eosinophilia, and decreased expression of the Th2 cytokine IL-13 and the leukotriene-synthesizing enzymes 5-lipoxygenase and leukotriene-C4-synthase. Plgf-/- mice treated with leukotrienes phenocopied the WT response to allergen exposure; conversely, anti-PlGF Ab administration in WT animals blunted the AHR. Notably, Th2-mediated STAT6 activation further increased PlGF expression from lung epithelium, eosinophils, and macrophages, creating a PlGF/leukotriene/Th2-response positive feedback loop. Similarly, we found that the Th2 response in asthma patients is associated with increased expression of PlGF and its downstream genes in respiratory epithelial cells. In an SCD mouse model, we observed increased AHR and higher leukotriene levels that were abrogated by anti-PlGF Ab or the 5-lipoxygenase inhibitor zileuton. Overall, our findings indicate that PlGF exacerbates AHR and uniquely links the leukotriene and Th2 pathways in asthma. These data also suggest that zileuton and anti-PlGF Ab could be promising therapies to reduce pulmonary morbidity in SCD.

Angiotensin-(1-7) Suppresses Hepatocellular Carcinoma Growth and Angiogenesis via Complex Interactions of Angiotensin II Type 1 Receptor, Angiotensin II Type 2 Receptor and Mas Receptor

We recently confirmed that angiotensin II (Ang II) type 1 receptor (AT1R) was overexpressed in hepatocellular carcinoma tissue using a murine hepatoma model. Angiotensin(Ang)-(1-7) has been found beneficial in ameliorating lung cancer and prostate cancer. Which receptor of Ang-(1-7) is activated to mediate its effects is much speculated. This study was designed to investigate the effects of Ang-(1-7) on hepatocellular carcinoma, as well as the probable mechanisms. H22 hepatoma-bearing mice were randomly divided into five groups for treatment: mock group, low-dose Ang-(1-7), high-dose Ang-(1-7), high-dose Ang-(1-7) + A779 and high-dose Ang-(1-7) + PD123319. Ang-(1-7) treatment inhibited tumor growth time- and dose-dependently by arresting tumor proliferation and promoting tumor apoptosis as well as inhibiting tumor angiogenesis. The effects of Ang-(1-7) on tumor proliferation and apoptosis were reversed by coadministration with A779 or PD123319, whereas the effects on tumor angiogenesis were completely reversed by A779 but not by PD123319. Moreover, Ang-(1-7) downregulated AT1R mRNA, upregulated mRNA levels of Ang II type 2 receptor (AT2R) and Mas receptor (MasR) and p38-MAPK phosphorylation and suppressed H22 cell-endothelial cell communication. Thus, Ang-(1-7) administration suppresses hepatocellular carcinoma via complex interactions of AT1R, AT2R and MasR and may provide a novel and promising approach for the treatment of hepatocellular carcinoma.

High-Mobility Group Box-1 Modulates the Expression of Inflammatory and Angiogenic Signaling Pathways in Diabetic Retina

PURPOSE

The expression of high-mobility group box-1 (HMGB1) is upregulated in epiretinal membranes and vitreous fluid from patients with proliferative diabetic retinopathy and in the diabetic retina. HMGB1 mediates inflammation, breakdown of the blood-retinal barrier and apoptosis in the diabetic retina. Here, we investigated inflammatory and angiogenic signaling pathways activated by HMGB1 in diabetic retina.

METHODS

Human retinal microvascular endothelial cells (HRMEC) and retinas from 1-month diabetic rats and normal rats intravitreally injected with HMGB1 were studied using RT-PCR, Western blot analysis and co-immunoprecipitation. We also studied the effect of the HMGB1 inhibitor glycyrrhizin on diabetes-induced biochemical changes in the retina.

RESULTS

Diabetes and intravitreal injection of HMGB1 in normal rats induced significant upregulation of the mRNA levels of the chemokine stromal cell-derived factor-1 (SDF-1/CXCL12) receptor CXCR4 and protein levels of hypoxia-inducible factor-1α, early growth response-1, tyrosine kinase 2 and the CXCL12/CXCR4 chemokine axis. Constant glycyrrhizin intake from onset of diabetes did not affect the metabolic status of the diabetic rats, but it restored these increased mediators to control values. Stimulation of HRMEC with HMGB1 and intraviteral injection of HMGB1 significantly increased the expression of vascular endothelial growth factor (VEGF) and VEGF receptor-2. Co-immunoprecipitation studies showed that diabetes increased the interaction between CXCL12 and CXCR4 and between HMGB1 and receptor for advanced glycation end products (RAGE), but not between HMGB1 and the CXCL12/CXCR4 chemokine axis.

CONCLUSIONS

Our findings suggest that HMGB1 activates inflammatory and angiogenic signaling pathways in diabetic retina mediated by RAGE.

TCDD induces the hypoxia-inducible factor (HIF)-1α regulatory pathway in human trophoblastic JAR cells

The exposure to dioxin can compromise pregnancy outcomes and increase the risk of preterm births. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been demonstrated to induce placental hypoxia at the end of pregnancy in a rat model, and hypoxia has been suggested to be the cause of abnormal trophoblast differentiation and placental insufficiency syndromes. In this study, we demonstrate that the non-hypoxic stimulation of human trophoblastic cells by TCDD strongly increased hypoxia inducible factor-1 alpha (HIF-1α) stabilization. TCDD exposure induced the generation of reactive oxygen species (ROS) and nitric oxide. TCDD-induced HIF-1α stabilization and Akt phosphorylation was inhibited by pretreatment with wortmannin (a phosphatidylinositol 3-kinase (PI3K) inhibitor) or N-acetylcysteine (a ROS scavenger). The augmented HIF-1α stabilization by TCDD occurred via the ROS-dependent activation of the PI3K/Akt pathway. Additionally, a significant increase in invasion and metallomatrix protease-9 activity was found in TCDD-treated cells. The gene expression of vascular endothelial growth factor and placental growth factor was induced upon TCDD stimulation, whereas the protein levels of peroxisome proliferator-activated receptor γ (PPARγ), PPARγ coactivator-1α, mitochondrial transcription factor, and uncoupling protein 2 were decreased. Our results indicate that an activated HIF-1α pathway, elicited oxidative stress, and induced metabolic stress contribute to TCDD-induced trophoblastic toxicity. These findings may provide molecular insight into the TCDD-induced impairment of trophoblast function and placental development.

Heme-bound iron activates placenta growth factor in erythroid cells via erythroid Krüppel-like factor

In adults with sickle cell disease (SCD), markers of iron burden are associated with excessive production of the angiogenic protein placenta growth factor (PlGF) and high estimated pulmonary artery pressure. Enforced PlGF expression in mice stimulates production of the potent vasoconstrictor endothelin-1, producing pulmonary hypertension. We now demonstrate heme-bound iron (hemin) induces PlGF mRNA >200-fold in a dose- and time-dependent fashion. In murine and human erythroid cells, expression of erythroid Krüppel-like factor (EKLF) precedes PlGF, and its enforced expression in human erythroid progenitor cells induces PlGF mRNA. Hemin-induced expression of PlGF is abolished in EKLF-deficient murine erythroid cells but rescued by conditional expression of EKLF. Chromatin immunoprecipitation reveals that EKLF binds to the PlGF promoter region. SCD patients show higher level expression of both EKLF and PlGF mRNA in circulating blood cells, and markers of iron overload are associated with high PlGF and early mortality. Finally, PlGF association with iron burden generalizes to other human diseases of iron overload. Our results demonstrate a specific mechanistic pathway induced by excess iron that is linked in humans with SCD and in mice to markers of vasculopathy and pulmonary hypertension. These trials were registered at www.clinicaltrials.gov as #NCT00007150, #NCT00023296, #NCT00081523, and #NCT00352430.

Egr-1 mediates chronic hypoxia-induced renal interstitial fibrosis via the PKC/ERK pathway

BACKGROUND

Chronic hypoxia-induced epithelial-to-mesenchymal transition (EMT) is a crucial process in renal fibrogenesis. Egr-1, as a transcription factor, has been proven to be important in promoting EMT. However, whether it functions in hypoxia-induced renal tubular EMT has not been fully elucidated.

METHODS

Egr-1 were detected at mRNA and protein levels by qPCR and Western blot analysis respectively after renal epithelial cells were subjected to hypoxia treatment. Meanwhile, EMT phenotype was also observed through identification of relevant EMT-specific markers. siRNA was used to knock down Egr-1 expression and subsequent changes were observed. Specific PKC and MAPK/ERK inhibitors were employed to determine the molecular signaling pathway involved in Egr-1-mediated EMT phenotype. In vivo assays using rat remnant kidney model were used to validate the in vitro results. Furthermore, Egr-1 expression was examined in the samples of CKD patients with the clinical relevance revealed.

RESULTS

Hypoxia treatment enhanced the mRNA and protein levels of Egr-1 in HK-2 cells, which was accompanied by a reduced expression of the epithelial marker E-cadherin and an enhanced expression of the mesenchymal marker Fsp-1. Downregulation of Egr-1 with siRNA reversed hypoxia-induced EMT. Using the specific inhibitors to protein kinase C (calphostin C) or MAPK/ERK (PD98059), we identified that hypoxia induced Egr-1 expression through the PKC/ERK pathway. In addition, the upregulation of Egr-1 raised endogenous Snail levels, and the downregulation of Snail inhibited Egr-1-mediated EMT in HK-2 cells. Through in vivo assays using rat remnant kidney and CKD patients' kidney tissues, we found that Egr-1 and Snail were overexpressed in tubular epithelial cells with EMT.

CONCLUSION

Egr-1 may be an important regulator of the development of renal tubular EMT induced by hypoxia through the PKC/ERK pathway and the activation of Snail. Targeting Egr-1 expression or activity might be a novel therapeutic strategy to control renal fibrosis.

Epigenetic control of hypoxia inducible factor-1α-dependent expression of placental growth factor in hypoxic conditions

Hypoxia plays a crucial role in the angiogenic switch, modulating a large set of genes mainly through the activation of hypoxia-inducible factor (HIF) transcriptional complex. Endothelial cells play a central role in new vessels formation and express placental growth factor (PlGF), a member of vascular endothelial growth factor (VEGF) family, mainly involved in pathological angiogenesis. Despite several observations suggest a hypoxia-mediated positive modulation of PlGF, the molecular mechanism governing this regulation has not been fully elucidated. We decided to investigate if epigenetic modifications are involved in hypoxia-induced PlGF expression. We report that PlGF expression was induced in cultured human and mouse endothelial cells exposed to hypoxia (1% O 2), although DNA methylation at the Plgf CpG-island remains unchanged. Remarkably, robust hyperacetylation of histones H3 and H4 was observed in the second intron of Plgf, where hypoxia responsive elements (HREs), never described before, are located. HIF-1α, but not HIF-2α, binds to identified HREs. Noteworthy, only HIF-1α silencing fully inhibited PlGF upregulation. These results formally demonstrate a direct involvement of HIF-1α in the upregulation of PlGF expression in hypoxia through chromatin remodeling of HREs sites. Therefore, PlGF may be considered one of the putative targets of anti-HIF therapeutic applications.

Transcriptional repression of hypoxia-inducible factor-1 (HIF-1) by the protein arginine methyltransferase PRMT1

Hypoxia-inducible factors (HIF) are essential for the adaptive response of cells to low-oxygen conditions. Transcription of HIF-α subunits and HIF activity are repressed by the arginine methyltransferase PRMT1. Therefore PRMT1 is a novel regulator of hypoxic cell responses.

Hypoxia-inducible factors (HIF-1 and HIF-2) are essential mediators for the adaptive transcriptional response of cells and tissues to low-oxygen conditions. Under hypoxia or when cells are treated with various nonhypoxic stimuli, the active HIF-α subunits are mainly regulated through increased protein stabilization. For HIF-1α, it is clear that further transcriptional, translational, and posttranslational regulations are important for complete HIF-1 activity. Novel evidence links hypoxia and HIF-1 to arginine methylation, an important protein modification. These studies suggest that arginine methyltransferases may be important for hypoxic responses. Protein arginine methyltransferase 1 (PRMT1), the predominant arginine methyltransferase, can act as a transcriptional activator or repressor by modifying a diverse set of substrates. In this work, we show that PRMT1 is a repressor of both HIF-1 and HIF-2. The cellular depletion of PRMT1 by small interference RNA targeting leads to increased HIF transcriptional activity. This activation is the result of enhanced HIF-α subunit transcription, which allows increased HIF-α subunit availability. We provide evidence that PRMT1-dependent HIF-1α regulation is mediated through the activities of both specificity protein 1 (Sp1) and Sp3, two transcription factors known to control HIF-1α expression. This study therefore identifies PRMT1 as a novel regulator of HIF-1– and HIF-2–mediated responses.

Targeting VEGFR1 on endothelial progenitors modulates their differentiation potential

OBJECTIVES

We studied whether plasma levels of angiogenic factors VEGF and placental growth factor (PlGF) in coronary artery disease patients or undergoing cardiac surgery are modified, and whether those factors modulate endothelial progenitor's angiogenic potential.

METHODS AND RESULTS

A total of 143 patients' plasmas from two different studies were analyzed (30 coronary artery disease patients, 30 patients with stable angina, coupled with 30 age and sex-matched controls; 53 patients underwent cardiac surgery). Among factors screened, only PlGF was found significantly increased in these pathological populations. PlGF-1 and PlGF-2 were then tested on human endothelial-colony-forming cells (ECFCs). We found that PlGF-1 and PlGF-2 induce VEGFR1 phosphorylation and potentiate ECFCs tubulogenesis in vitro. ECFCs VEGFR1 was further inhibited using a specific small interfering RNA (siRNA) and the chemical compound 4321. We then observed that the VEGFR1-siRNA and the compound 4321 decrease ECFCs tubulogenesis potential in vitro. Finally, we tested the compound 4321 in the preclinical Matrigel(®)-plug model with C57Bl/6J mice as well as in the murine hindlimb ischemia model. We found that 4321 inhibited the plug vascularization, attested by the hemoglobin content and the VE-Cadherin expression level and that 4321 inhibited the post-ischemic revascularization.

CONCLUSION

PlGF plasma levels were found increased in cardiovascular patients. Disrupting PlGF/VEGFR1 pathway could modulate ECFC-induced tubulogenesis, the cell type responsible for newly formed vessels in vivo.

Hypoxia and lymphangiogenesis in tumor microenvironment and metastasis

Hypoxia and lymphangiogenesis are closely related processes that play a pivotal role in tumor invasion and metastasis. Intratumoral hypoxia is exacerbated as a result of oxygen consumption by rapidly proliferating tumor cells, insufficient blood supply and poor lymph drainage. Hypoxia induces functional responses in lymphatic endothelial cells (LECs), including cell proliferation and migration. Multiple factors (e.g., ET-1, AP-1, C/EBP-δ, EGR-1, NF-κB, and MIF) are involved in the events of hypoxia-induced lymphangiogenesis. Among them, HIF-1α is known to be the master regulator of cellular oxygen homeostasis, mediating transcriptional activation of lymphangiogenesis via regulation of signaling cascades like VEGF-A/-C/-D, TGF-β and Prox-1 in experimental and human tumors. Although the underlying molecular mechanisms remain incompletely elucidated, the investigation of lymphangiogenesis in hypoxic conditions may provide insight into potential therapeutic targets for lymphatic metastasis.

Information exploration system for sickle cell disease and repurposing of hydroxyfasudil

Background

Sickle cell disease (SCD) is a fatal monogenic disorder with no effective cure and thus high rates of morbidity and sequelae. Efforts toward discovery of disease modifying drugs and curative strategies can be augmented by leveraging the plethora of information contained in available biomedical literature. To facilitate research in this direction we have developed a resource, Dragon Exploration System for Sickle Cell Disease (DESSCD) (http://cbrc.kaust.edu.sa/desscd/) that aims to promote the easy exploration of SCD-related data.

Description

The Dragon Exploration System (DES), developed based on text mining and complemented by data mining, processed 419,612 MEDLINE abstracts retrieved from a PubMed query using SCD-related keywords. The processed SCD-related data has been made available via the DESSCD web query interface that enables: a/information retrieval using specified concepts, keywords and phrases, and b/the generation of inferred association networks and hypotheses. The usefulness of the system is demonstrated by: a/reproducing a known scientific fact, the “Sickle_Cell_Anemia–Hydroxyurea” association, and b/generating novel and plausible “Sickle_Cell_Anemia–Hydroxyfasudil” hypothesis. A PCT patent (PCT/US12/55042) has been filed for the latter drug repurposing for SCD treatment.

Conclusion

We developed the DESSCD resource dedicated to exploration of text-mined and data-mined information about SCD. No similar SCD-related resource exists. Thus, we anticipate that DESSCD will serve as a valuable tool for physicians and researchers interested in SCD.

Oxidative status interactome map: towards novel approaches in experiment planning, data analysis, diagnostics and therapy

Experimental evidence suggests an immense variety of processes associated with and aimed at producing reactive oxygen and/or nitrogen species. Clinical studies implicate an enormous range of pathologies associated with reactive oxygen/nitrogen species metabolism deregulation, particularly oxidative stress. Recent advances in biochemistry, proteomics and molecular biology/biophysics of cells suggest oxidative stress to be an endpoint of complex dysregulation events of conjugated pathways consolidated under the term, proposed here, "oxidative status". The oxidative status concept, in order to allow for novel diagnostic and therapeutic approaches, requires elaboration of a new logic system comprehending all the features, versatility and complexity of cellular pro- and antioxidative components of different nature. We have developed a curated and regularly updated interactive interactome map of human cellular-level oxidative status allowing for systematization of the related most up-to-date experimental data. A total of more than 600 papers were selected for the initial creation of the map. The map comprises more than 300 individual factors with respective interactions, all subdivided hierarchically for logical analysis purposes. The pilot application of the interactome map suggested several points for further development of oxidative status-based technologies.

Transfected early growth response gene-1 DNA enzyme prevents stenosis and occlusion of autogenous vein graft in vivo

The aim of this study was to detect the inhibitory action of the early growth response gene-1 DNA enzyme (EDRz) as a carrying agent by liposomes on vascular smooth muscle cell proliferation and intimal hyperplasia. An autogenous vein graft model was established. EDRz was transfected to the graft vein. The vein graft samples were obtained on each time point after surgery. The expression of the EDRz transfected in the vein graft was detected using a fluorescent microscope. Early growth response gene-1 (Egr-1) mRNA was measured using reverse transcription-PCR and in situ hybridization. And the protein expression of Egr-1 was detected by using western blot and immunohistochemistry analyses. EDRz was located at the media of the vein graft from 2 to 24 h, 7 h after grafting. The Egr-1 protein was mainly located in the medial VSMCs, monocytes, and endothelium cells during the early phase of the vein graft. The degree of VSMC proliferation and thickness of intima were obviously relieved compared with the no-gene therapy group. EDRz can reduce Egr-1 expression in autogenous vein grafts, effectively restrain VSMC proliferation and intimal hyperplasia, and prevent vascular stenosis and occlusion after vein graft.

Involvement of early growth response factors in TNFα-induced aromatase expression in breast adipose

Expression of the oestrogen producing enzyme, aromatase, is regulated in a tissue-specific manner by its encoding gene CYP19A1. In post-menopausal women, the major site for oestrogen production in the breast is the adipose, where CYP19A1 transcription is driven by the distal promoter I.4 (PI.4). Transcripts via this promoter are also elevated in breast adipose fibroblasts (BAFs) adjacent to a tumour. PI.4 expression is stimulated by a number of cytokines, and TNFα is one such factor. The transcriptional mechanisms induced by TNFα to stimulate PI.4 are poorly characterised. We show that the early growth response (Egr) transcription factors play an important role in the TNFα-induced signalling pathway resulting in elevated PI.4 transcription. TNFα treatment of BAFs increases mRNA levels of all four Egr family members, with EGR2 being the most highly expressed. Overexpression of EGR2 causes an increase in endogenous CYP19A1 expression in preadipocyte Simpson-Golabi-Behmel syndrome cells, driven by increases in PI.4-specific transcripts. PI.4 luciferase reporter activity is increased in a dose-dependent manner by EGR2, EGR3 and EGR4, with EGR2 showing the most potent activation of promoter activity. Deletion analysis indicates that this promoter activity is being indirectly mediated by a short region of the promoter not containing any previously characterised binding sites, and we further show that EGR2 does not bind directly or indirectly to this promoter region. However, siRNA knockdown of the Egrs reduces the total and PI.4-derived CYP19A1 transcription in BAFs. These studies unveil a novel component of the aromatase gene regulatory network and further enhance the complexity of oestrogen production in the breast.

Human apurinic/apyrimidinic endonuclease siRNA inhibits the angiogenesis induced by X-ray irradiation in lung cancer cells

OBJECTIVE

Radiotherapy is an important and effective treatment method for non-small cell lung cancer (NSCLC). Nonetheless, radiotherapy can alter the expression of proangiogenic molecules and induce angiogenesis. Human apurinic/apyrimidinic endonuclease (APE1) is a multifunctional protein, which has DNA repair and redox function. Our previous studies indicated APE1 is also a crucial angiogenic regulator. Thus, we investigated the effect of APE1 on radiation-induced angiogenesis in lung cancer and its underlying mechanism.

METHODS

Tumor specimens of 136 patients with NSCLC were obtained from 2003 to 2008. The APE1 and vascular endothelial growth factor (VEGF) expression, as well as microvessel density (MVD) were observed with immunohistochemistry in tumor samples. Human lung adenocarcinoma A549 cells were treated with Ad5/F35-APE1 siRNA and/or irradiation, and then the cells were used for APE1 analysis by Western blot and VEGF analysis by RT-PCR and ELISA. To elucidate the underline mechanism of APE1 on VEGF expression, HIF-1α protein level was determined by Western blot, and the DNA binding activity of HIF-1α was detected by EMSA. Transwell migration assay and capillary-like structure assay were used to observe the migration and capillary-like structure formation ability of human umbilical veins endothelial cells (HUVECs) that were co-cultured with Ad5/F35-APE1 siRNA and (or) irradiation treated A549 cells culture medium.

RESULTS

The high expression rates of APE1 and VEGF in NSCLC were 77.94% and 66.18%, respectively. The expressions of APE1 was significantly correlated with VEGF and MVD (r=0.369, r=0.387). APE1 and VEGF high expression were significantly associated with reduced disease free survival (DFS) time. The high expressions of APE1 and VEGF on A549 cells were concurrently induced by X-ray irradiation in a dose-dependent manner. Silencing of APE1 by Ad5/F35-APE1 siRNA significantly decreased DNA binding activity of HIF-1α and suppressed the expression of VEGF in A549 cells, moreover, significantly inhibited the endothelial cells immigration and capillary-like structure formation induced by irradiated A549 cells.

CONCLUSION

Our results indicate that APE1 may play a crucial role in angiogenesis induced by irradiation. Administration of Ad5/F35-APE1 siRNA during radiotherapy could be a potent adjuvant therapeutic approach to enhance the radiotherapy response, effectively eliminate metastasis and improve the efficacy of radiotherapy for NSCLC.

Reverse translation of phase I biomarker findings links the activity of angiotensin-(1-7) to repression of hypoxia inducible factor-1α in vascular sarcomas

Background

In a phase I study of angiotensin-(1–7) [Ang-(1–7)], clinical benefit was associated with reduction in plasma placental growth factor (PlGF) concentrations. The current study examines Ang-(1–7) induced changes in biomarkers according to cancer type and investigates mechanisms of action engaged in vitro.

Methods

Plasma biomarkers were measured prior to Ang-(1–7) administration as well as 1, 2, 3, 4, and 6 hours after treatment. Tests for interaction were performed to determine the impact of cancer type on angiogenic hormone levels. If a positive interaction was detected, treatment-induced biomarker changes for individual cancer types were assessed. To investigate mechanisms of action, in vitro growth assays were performed using a murine endothelioma cell line (EOMA). PCR arrays were performed to identify and statistically validate genes that were altered by Ang-(1–7) treatment in these cells.

Results

Tests for interaction controlled for dose cohort and clinical response indicated a significant impact of cancer type on post-treatment VEGF and PlGF levels. Following treatment, PlGF levels decreased over time in patients with sarcoma (P = .007). Treatment of EOMA cells with increasing doses of Ang-(1–7) led to significant growth suppression at doses as low as 100 nM. PCR arrays identified 18 genes that appeared to have altered expression after Ang-(1–7) treatment. Replicate analyses confirmed significant changes in 8 genes including reduction in PlGF (P = .04) and hypoxia inducible factor 1α (HIF-1α) expression (P < .001).

Conclusions

Ang-(1–7) has clinical and pre-clinical activity for vascular sarcomas that is linked to reduced HIF-1α and PlGF expression.

Pseudomonas aeruginosa Alkyl quinolones repress hypoxia-inducible factor 1 (HIF-1) signaling through HIF-1α degradation

The transcription factor hypoxia-inducible factor 1 (HIF-1) has recently emerged to be a crucial regulator of the immune response following pathogen perception, including the response to the important human pathogen Pseudomonas aeruginosa. However, as mechanisms involved in HIF-1 activation by bacterial pathogens are not fully characterized, understanding how bacteria and bacterial compounds impact on HIF-1α stabilization remains a major challenge. In this context, we have focused on the effect of secreted factors of P. aeruginosa on HIF-1 regulation. Surprisingly, we found that P. aeruginosa cell-free supernatant significantly repressed HIF-1α protein levels. Further characterization revealed that HIF-1α downregulation was dependent on a subset of key secreted factors involved in P. aeruginosa pathogenesis, the 2-alkyl-4-quinolone (AQ) quorum sensing (QS) signaling molecules, and in particular the pseudomonas quinolone signal (PQS). Under hypoxic conditions, the AQ-dependent downregulation of HIF-1α was linked to the suppressed induction of the important HIF-1 target gene hexokinase II. Furthermore, we demonstrated that AQ molecules directly target HIF-1α protein degradation through the 26S-proteasome proteolytic pathway but independently of the prolyl hydroxylase domain (PHD). In conclusion, this is the first report showing that bacterial molecules can repress HIF-1α protein levels. Manipulation of HIF-1 signaling by P. aeruginosa AQs could have major consequences for the host response to infection and may facilitate the infective properties of this pathogen.

PlGF: a multitasking cytokine with disease-restricted activity

Placental growth factor (PlGF) is a member of the vascular endothelial growth factor (VEGF) family that also comprises VEGF-A (VEGF), VEGF-B, VEGF-C, and VEGF-D. Unlike VEGF, PlGF is dispensable for development and health but has diverse nonredundant roles in tissue ischemia, malignancy, inflammation, and multiple other diseases. Genetic and pharmacological gain-of-function and loss-of-function studies have identified molecular mechanisms of this multitasking cytokine and characterized the therapeutic potential of delivering or blocking PlGF for various disorders.

Involvement of miR-30c and miR-301a in immediate induction of plasminogen activator inhibitor-1 by placental growth factor in human pulmonary endothelial cells

PAI-1 (plasminogen activator inhibitor-1) is a key physiological inhibitor of fibrinolysis. Previously, we have reported PlGF (placental growth factor)-mediated transcriptional up-regulation of PAI-1 (SERPINE1) mRNA expression via activation of HIF-1α (hypoxia-inducible factor-1α) and AP-1 (activator protein-1) in HPMVECs (human pulmonary microvascular endothelial cells), which resulted in elevated PAI-1 in humans with SCA (sickle cell anaemia). In the present study, we have identified the role of post-transcriptional mechanism(s) of PlGF-mediated accumulation of PAI-1 mRNA in HPMVECs by examining the role of microRNAs (miRNAs/miRs) in PlGF-induced PAI-1 mRNA stability. Our results show reduced expression of miR-30c and miR-301a, but not of miR-99a, in response to PlGF, which have evolutionarily conserved binding sites in the 3'-UTR (3'-untranslated region) of PAI-1 mRNA. Transfection of anti-miR-30c or anti-miR-301a oligonucleotides resulted in increased PAI-1 mRNA levels, which were increased further with PlGF stimulation. Conversely, overexpression of pre-miR-30c or pre-miR-301a resulted in an attenuation of PlGF-induced PAI-1 mRNA and protein levels. Luciferase reporter assays using wild-type and mutant 3'-UTR constructs confirmed that the PAI-1 3'-UTR is indeed a direct target of miR-30c and miR-301a. Finally, plasma levels of miR-30c and miR-301a were significantly down-regulated in patients with SCA compared with normal controls. These results provide a post-transcriptional regulatory mechanism of PlGF-induced PAI-1 elevation.