The novel angiogenesis regulator circFAM169A promotes the metastasis of colorectal cancer through the angiopoietin-2 signaling axis

BACKGROUND

Angiogenesis plays an important role in the metastasis of cancers. However, the mechanisms whereby circular RNAs (circRNAs) regulate angiogenesis and affect cancer metastasis are still unclear.

METHODS

We used gene set variation and Spearman's correlation analyses to identify novel angiogenesis-related circRNAs, including circFAM169A. The Kyoto Encyclopedia of Genes and Genomes and Gene Ontology were used to assess the potential biological function of circFAM169A. A quantitative reverse transcription-PCR (qRT-PCR) analysis of 20 pairs of colorectal cancer (CRC) samples was performed to detect the expression level of circFAM169A. Transwell assays, tube formation assays, and nude mouse metastatic tumor models were used to study the function of circFAM169A in CRC. qRT-PCR, dual-luciferase reporter gene assay, RNA antisense purification assay, and Western blot were performed to analyze the competing endogenous RNA mechanism of circFAM169A in promoting CRC angiogenesis.

RESULTS

circFAM169A was highly correlated with the hallmark of angiogenesis in CRC patients. It was up-regulated in liver metastasized CRC patients. circFAM169A overexpression promoted the angiogenesis, migration, and invasion of CRC cells while its down-regulation had the opposite effects. In vivo mouse models further highlighted the pro-metastatic role of circFAM169A in CRC. More importantly, we discovered that circFAM169A enhances the expression of angiopoietin-2 by binding to miR-518a-5p.

Helicobacter pylori infection induces abnormal expression of pro-angiogenic gene ANGPT2 and miR-203a in AGS gastric cell line

Helicobacter pylori colonizes the stomach and induces an inflammatory response that can develop into gastric pathologies including cancer. The infection can alter the gastric vasculature by the deregulation of angiogenic factors and microRNAs. In this study, we investigate the expression level of pro-angiogenic genes (ANGPT2, ANGPT1, receptor TEK), and microRNAs (miR-135a, miR-200a, miR-203a) predicted to regulate those genes, using H. pylori co-cultures with gastric cancer cell lines. In vitro infections of different gastric cancer cell lines with H. pylori strains were performed, and the expression of ANGPT1, ANGPT2, and TEK genes, and miR-135a, miR-200a, and miR-203a, was quantified after 24 h of infection (h.p.i.). We performed a time course experiment of H. pylori 26695 infections in AGS cells at 6 different time points (3, 6, 12, 28, 24, and 36 h.p.i.). The angiogenic response induced by supernatants of non-infected and infected cells at 24 h.p.i. was evaluated in vivo, using the chicken chorioallantoic membrane (CAM) assay. In response to infection, ANGPT2 mRNA was upregulated at 24 h.p.i, and miR-203a was downregulated in AGS cells co-cultured with different H. pylori strains. The time course of H. pylori 26695 infection in AGS cells showed a gradual decrease of miR-203a expression concomitant with an increase of ANGPT2 mRNA and protein expression. Expression of ANGPT1 and TEK mRNA or protein could not be detected in any of the infected or non-infected cells. CAM assays showed that the supernatants of AGS-infected cells with 26695 strain induced a significantly higher angiogenic and inflammatory response. Our results suggest that H. pylori could contribute to the process of carcinogenesis by downregulating miR-203a, which further promotes angiogenesis in gastric mucosa by increasing ANGPT2 expression. Further investigation is needed to elucidate the underlying molecular mechanisms.

Helicobacter pylori infection induces gastric precancerous lesions and persistent expression of Angpt2, Vegf-A and Tnf-A in a mouse model

Introduction

Helicobacter pylori colonizes the gastric mucosa and induces chronic inflammation.

Methods

Using a mouse model of H. pylori-induced gastritis, we evaluated the mRNA and protein expression levels of proinflammatory and proangiogenic factors, as well as the histopathological changes in gastric mucosa in response to infection. Five- to six-week-old female C57BL/6N mice were challenged with H. pylori SS1 strain. Animals were euthanized after 5-, 10-, 20-, 30-, 40- and 50-weeks post infection. mRNA and protein expression of Angpt1, Angpt2, VegfA, Tnf-α, bacterial colonization, inflammatory response and gastric lesions were evaluated.

Results

A robust bacterial colonization was observed in 30 to 50 weeks-infected mice, which was accompanied by immune cell infiltration in the gastric mucosa. Compared to non-infected animals, H. pylori-colonized animals showed an upregulation in the expression of Tnf-A, Angpt2 and VegfA at the mRNA and protein levels. In contrast, Angpt1 mRNA and protein expression was downregulated in H. pylori-colonized mice.

Conclusion

Our data show that H. pylori infection induces the expression of Angpt2, Tnf-A and Vegf-A in murine gastric epithelium. This may contribute to the pathogenesis of H. pylori-associated gastritis, however the significance of this should be further addressed.

Assessment of Angiopoietin-2 Single Nucleotide Polymorphism in Patients with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that destroys joint cartilage and causes disability. Synovial inflammation, with angiogenesis, is an early event in the progression of the disease. Angiopoietin 2 (ANGPT2) is a cytokine with both inflammatory and angiogenic effects. Many genes can influence RA susceptibility and disease activity. The aim is to assess the relationship between ANGPT2 gene polymorphism (rs3020221) and RA. The study was a case-control study that included 212 RA patients and 238 age-and gender-matched healthy volunteers. RA disease activity was assessed using the Disease Activity Score 28 index. Erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, and antibody to cyclic citrullinated peptide were measured. ANGPT2 rs3020221 C > T SNP genotyping was done using real-time polymerase chain reaction (PCR). The TT genotype was more frequently represented in RA patients than in healthy controls (18.9% and 7.1%, respectively, p < 0.001) and increased the chance of developing RA four-fold, as compared to other genotypes (OR = 4.00, 95% CI = 2.09-7.63) (p < 0.001). The CT genotype was associated with elevated levels of the inflammatory markers ESR and CRP in RA patients (p = 0.012 and 0.037, respectively) as well as the DAS28 ESR Score (p < 0.001). The presence of the T allele either under the dominant model (for genotypes CT and TT) or the recessive model (for the genotype TT) predicts RA disease. Assessment of ANGPT2 gene polymorphism is useful to predict the patients with susceptibility to RA. The presence of T allele increased the risk of developing RA disease by two folds.

Selective adipocyte loss of Angiopoietin-2 prompts female-specific obesity and metabolic syndrome

Thermogenic fat differentiation and function can be promoted through multiple pathways, resulting in a common cell phenotype characterized by the expression of Uncoupling Protein-1 and the ability to dissipate energy, but local and systemic stimuli are necessary to promote adequate thermogenic fat vascularization, which is a precondition for the transport of substrate and the dissipation of heat. Angiopoietin-2 is an important driver of vascularization, and its transcription is in part promoted by estrogen signaling. In this study we demonstrate that adipose tissue-specific knock out of Angiopoietin-2 causes a female-specific reduced thermogenic fat differentiation and function, resulting in obesity and impaired glucose tolerance with end-organ features consistent with metabolic syndrome. In humans, angiopoietin-2 levels are higher in females than in males, and are inversely correlated with adiposity and age more strongly in pre-menopause when compared to post-menopause. Collectively, these data indicate a novel and important role for estrogen-mediated Angiopoietin-2 adipose tissue production in the protection against calorie overload in females, and potentially in the development of postmenopausal weight gain.

Genetic association of ANGPT2 with primary open-angle glaucoma

BACKGROUND

To determine the association of the ANGPT2 gene with primary open-angle glaucoma (POAG) in Chinese.

METHODS

Six single-nucleotide polymorphisms (SNPs) in ANGPT2 (rs2515487, rs2922869, rs13255574, rs4455855, rs13269021, and rs11775442) were genotyped in a total of 2601 study subjects from two cohorts. One is a Hong Kong Chinese cohort of 484 high tension glaucoma (HTG) and 537 normal tension glaucoma (NTG) patients, and 496 non-glaucoma control subjects. Another cohort is a Shantou Chinese cohort of 403 HTG and 135 NTG patients, and 543 non-glaucoma control subjects. Subgroup analysis by sex was conducted. Outcomes from different cohorts were combined for meta-analysis.

RESULTS

The association of SNP rs11775442 with NTG in the Hong Kong cohort [P = 0.0498, OR = 1.24, 95% confidence interval (CI) 1.00-1.55] after adjusting for age and sex did not reach statistical significance after Bonferroni correction. Other SNPs were not significantly associated with NTG, HTG and POAG in individual cohort or in the combined analyses (P > 0.05). In the subgroup analysis by sex, SNP rs13269021 in the Shantou cohort, but not in the Hong Kong cohort, was significantly associated with NTG in males (P = 0.0081, OR = 1.67, 95% CI: 1.14-2.43) but not in females (P = 0.874). In the combined analyses by sex, no SNPs were significantly associated with NTG, HTG and POAG.

CONCLUSIONS

In the subgroup analysis by sex, a significant association was shown in SNP rs13269021 with NTG in Shantou males, but not in Hong Kong males. Further studies are needed to verify the association between ANGPT2 locus (rs13269021) and NTG in Chinese males.

MiR-29a Curbs Hepatocellular Carcinoma Incidence via Targeting of HIF-1α and ANGPT2

A high-fat diet is responsible for hepatic fat accumulation that sustains chronic liver damage and increases the risks of steatosis and hepatocellular carcinoma (HCC). MicroRNA-29a (miR-29a), a key regulator of cellular behaviors, is present in anti-fibrosis and modulator tumorigenesis. However, the increased transparency of the correlation between miR-29a and the progression of human HCC is still further investigated. In this study, we predicted HIF-1α and ANGPT2 as regulators of HCC by the OncoMir cancer database and showed a strong positive correlation with HIF-1α and ANGPT2 gene expression in HCC patients. Mice fed the western diet (WD) while administered CCl4 for 25 weeks induced chronic liver damage and higher HCC incidence than without fed WD mice. HCC section staining revealed signaling upregulation in ki67, severe fibrosis, and steatosis in WD and CCl4 mice and detected Col3a1 gene expressions. HCC tissues significantly attenuated miR-29a but increased in HIF-1α, ANGPT2, Lox, Loxl2, and VEGFA expression. Luciferase activity analysis confirms that miR-29a specific binding 3′UTR of HIF-1α and ANGPT2 to repress expression. In summary, miR-29a control HIF-1α and ANGPT2 signaling in HCC formation. This study insight into a novel molecular pathway by which miR-29a targeting HIF-1α and ANGPT2 counteracts the incidence of HCC development.

Distinct effects of ANGPT2 on gene expression of glomerular podocytes and mesangial cells

Glomerular diseases are the leading cause of chronic kidney diseases with the pathomechanisms largely unclear. ANGPT2 is known to regulate endothelial cell homeostasis through TEK/Tie2 and its dysregulation causes endothelial damage. Here, we found that ANGPT2 is upregulated in glomerular diseases and wondered whether it also acts on the other two glomerular cell types, podocytes and mesangial cells. We treated podocytes and mesangial cells in culture with ANGPT2 but didn't find changes in morphology and survival. RNA-seq analysis revealed that gene expression was altered in both podocytes and mesangial cells and that the differentially expressed genes in the two cell types were fundamentally different and enriched in distinct cellular processes and pathways according to GO and KEGG analyses. Mechanistically, the Ingenuity Pathway Analysis (IPA) analysis revealed that ERK and AKT were the most connected nodes in the networks of the regulated genes of both podocytes and mesangial cells, suggesting that ANGPT2 affected ERK and AKT in both cell types. Interestingly, immunoblotting showed that phosphorylated ERK and AKT were both increased in podocytes while decreased in mesangial cells by ANGPT2. We found that mesangial cells, but not podocytes, expressed TEK and ANGPT1, suggesting that ANGPT2 could antagonize ANGPT1-TEK-ERK axis in mesangial cells similarly to endothelial cells. We searched databases and found that integrin alpha(v) (ITGAV) is an ANGPT2 interacting protein and expressed in podocytes, suggesting that ITGAV mediates ANGPT2 effect on podocytes. In conclusion, increased ANGPT2 may be involved in glomerular injury by affecting podocytes and mesangial cells in addition to endothelial cells. The complexity of the effect of ANGPT2 in glomeruli may apply to other factors.

Angiopoietin-2 silence alleviates lipopolysaccharide-induced inflammation, barrier dysfunction and endoplasmic reticulum stress of intestinal epithelial cells by blocking Notch signaling pathway

Necrotizing enterocolitis, a devastating gastrointestinal disease with high mortality, poses great threats to global health. Therefore, we conducted this study to explore the role of ANGPT2, as well as the potential mechanism, in necrotizing enterocolitis. IEC-6 cells were stimulated with lipopolysaccharide (LPS) to induce necrotizing enterocolitis model in vitro. The expression of ANGPT2 was measured by RT-qPCR. The cell viability was detected using CCK-8. Besides, the expressions of endoplasmic reticulum (ER) stress-related proteins, Notch signaling pathway-related proteins and tight junction proteins were checked by western blot. The apoptosis and inflammatory response were detected by TUNEL and ELISA, respectively. Moreover, with the adoption of TEER, the cell monolayer permeability was detected. The results showed that ANGPT2 expression was greatly increased after LPS induction. In addition, ANGPT2 knockdown significantly decreased the apoptosis, inflammatory response, barrier dysfunction and endoplasmic reticulum stress of LPS-induced IEC-6 cells. What is more, ANGPT2 knockdown could block Notch signaling pathway. Additionally, with the treatment of Jagged-1, the protective effect of ANGPT2 knockdown on LPS-induced intestinal injury was partly abolished. To sum up, silencing ANGPT2 could improve LPS-induced inflammation, barrier dysfunction and ER stress of intestinal epithelial cells via blocking Notch signaling pathway.

LINC00184 involved in the regulatory network of ANGPT2 via ceRNA mediated miR-145 inhibition in gastric cancer

Background: Disrupted gene levels are intimately correlated with the occurrence and prognosis of gastric cancer (GC). As genes do not function in isolation, we set out to investigate the possible relationship among mRNA and non-coding RNAs (ncRNAs).

Materials and methods: RNA sequencing from 406 cases of GC was acquired through the TCGA database. R packages were utilized to assess differential RNA expression. The competing endogenous RNA (ceRNA) network was predicted using miRcode, miRDB, mirTarBase, Target Scan and constructed by Cytoscape 3.6.1. GO enrichment analysis, KEGG pathway analysis, GSEA, and WGCNA were applied for pathway analysis. The expression of select candidate molecules was confirmed using western blot and RT-PCR in GC cells and tissues. CCK-8, EdU staining, and Transwell assays were conducted to assess the influence of candidate molecules on proliferation and invasion. The gain and loss-of-function were achieved by co-culture with sh-lncRNA, mimics and sh-mRNA. Luciferase reporters were created using the psiCHECK2 vector, and the relative luciferase activity was calculated.

Results: Using data from TCGA, we determined differentially expressed RNAs and created a ceRNA regulatory network. Interestingly, we identified a regulatory complex surrounding ANGPT2. We detected that ANGPT2 was highly expressed in GC, which correlated with a worse prognosis. Our findings indicated that ANGPT2 encourages growth, invasion, and epithelial-mesenchymal transition (EMT) in GC. Importantly, miR-145 inhibits ANGPT2 and abrogates its effects. Furthermore, LINC00184, a ceRNA, blocks miR-145, thereby improving ANGPT2-mediated carcinogenesis.

Conclusions: Our findings indicate that the LINC00184/miR-145/ANGPT2 pathway has a crucial function in the development of GC and can act as a possible biomarker and targets for GC therapy.

MiR-145-5p suppresses the proliferation, migration and invasion of gastric cancer epithelial cells via the ANGPT2/NOD_LIKE_RECEPTOR axis

Objective

This study aimed to investigate the relationship among miR-145-5p, ANGPT2 and the NOD_LIKE_RECEPTOR pathway, thereby revealing the molecular mechanism of these three factors underlying the proliferation, migration and invasion of gastric cancer (GC) epithelial cells.

Methods

qRT-PCR was carried out to detect the expression of miR-145-5p and ANGPT2 mRNA. Western blot was performed to test the protein levels of ANGPT2 as well as NOD1, NOD2 and NF-κB in the NOD_LIKE_RECEPTOR pathway. The targeting relationship between miR-145-5p and ANGPT2 was verified via a dual-luciferase reporter gene assay. The proliferation, migration and invasion of GC cells were detected through MTT and Transwell assays, respectively.

Results

The expression of miR-145-5p was significantly down-regulated in GC cells, while that of ANGPT2 was notably up-regulated. MiR-145-5p directly bound with the 3′-UTR of ANGPT2 mRNA, thereby targeting ANGPT2 after transcription. Overexpression of miR-145-5p inhibited the proliferation, migration and invasion of GC cells by suppressing ANGPT2. Moreover, low expression of ANGPT2 affected the protein levels of NOD1, NOD2 and NF-κB in the NOD_LIKE_RECEPTOR pathway, thus weakening the abilities of cell proliferation, migration and invasion.

Conclusions

MiR-145-5p plays an important role in GC epithelial cells, and it can affect cell proliferation, migration and invasion of GC cells by targeting ANGPT2 and regulating the NOD_LIKE_RECEPTOR pathway. Overall, our study further elucidates the molecular mechanism underlying the malignant progression of GC.

Distinct Roles of VEGFA and ANGPT2 in Lung Adenocarcinoma and Squamous Cell Carcinoma

Background: Vascular endothelial growth factor A (VEGFA) and angiopoietin 2 (ANGPT2) are key mediators in angiogenesis. The expression and clinical significance of VEGFA and ANGPT2 have been investigated in lung cancer, but the results are controversial. The specific roles of VEGFA and ANGPT2 in adenocarcinoma (ADC) and squamous cell carcinoma (SQC) are still not fully understood. To characterize it, we conducted the current study.

Materials and Methods: The relationships between clinic-pathological characteristics and the protein expressions of VEGFA and ANGPT2 were analyzed on tissue microarrays by immunohistochemistry (IHC) staining. Then public databases were used to evaluate the association of VEGFA and ANGPT2 mRNA expressions with clinic-pathological parameters and prognosis. Cobalt chloride (CoCl₂) was adopted to mimic a hypoxic microenvironment and western blot was used to detect the expression of hypoxia inducible factor-1α (HIF-1α), VEGFA and ANGPT2 in lung cancer cell lines.

Results: IHC staining revealed that the expressions of VEGFA and ANGPT2 were enriched in lung cancer tissues compared with normal tissues. Additionally, both VEGFA and ANGPT2 protein levels were significantly associated with the tumor size and lymph node metastasis only in ADC, not SQC. More importantly, increased VEGFA and ANGPT2 protein levels were negatively correlated with overall survival (OS) of ADC individuals. Meta-analyses of 22 gene expression omnibus (GEO) databases of lung cancer implicated that patients with higher VEGFA and ANGPT2 mRNA expressions tended to have advanced stage in ADC rather than SQC. Kaplan-Meier plot analyses further verified that high levels of VEGFA and ANGPT2 mRNA were associated with poor survival only in ADC. Moreover, the combination of VEGFA and ANGPT2 could more precisely predict prognosis in ADC. In hypoxia-mimicking conditions, induced expression of HIF-1α unregulated VEGFA and ANGPT2 proteins abundance.

Conclusion: Our results showed hypoxia upregulated the protein levels of VEGFA and ANGPT2 in lung cancer cell lines, and the roles of VEGFA and ANGPT2 were distinct in ADC and SQC. Combined detections of VEGFA and ANGPT2 may be valuable prognostic biomarkers for ADC and double block of VEGFA and ANGPT2 may improve therapeutic outcome.

miR145 Regulates the Proliferation and Apoptosis of Rat Vascular Endothelial Cells under Hyperglycemia by Targeting the ANGPT2 Gene and Involving the NFκB Signaling Pathway

PURPOSE

A majority of diabetes mellitus patients with disturbances of glucose metabolism present with vascular complications. This study aimed to explore regulatory mechanisms of miR145 and its potential target gene ANGPT2 on diabetic vasculopathy under hyperglycemia.

METHODS

Based on the fact that miR145 is detected in rat aortic endothelial cells (RAECs) under hyperglycemia, RAECs were transfected with miR145 mimics/inhibitor for further confirmation. RAEC proliferation was detected with CCK8 assays, and cell apoptosis and CD34⁺-cell population with annexinV-PI staining and anti-CD34FITC on flow cytometry, respectively. Then, qPCR and Western blot were applied to detect mRNA and protein expression of ANGPT2 and involved pathway factor NFκB p65. Subsequently, dual luciferase-reporter gene analysis was utilized to verify whether miR145 acted directly upon the 3'UTR of ANGPT2 mRNA.

RESULTS

The ANGPT2 gene was confirmed to be a direct target of miR145. miR145 mimics markedly downregulated the expression of ANGPT2 and NFκB p65, boosted the percentage of the CD34⁺ phenotype, and promoted proliferation and suppressed apoptosis of RAECs under hyperglycemia.

CONCLUSION

miR145 might regulate the viability of RAECs via targeting ANGPT2 and involving NFκB signaling to exert a protective effect on diabetic vasculature.

miR-205-5p inhibits human endometriosis progression by targeting ANGPT2 in endometrial stromal cells

BACKGROUND

miRNA expression profiles in ectopic endometrium (EC) serving as pathophysiologic genetic fingerprints contribute to determining endometriosis progression; however, the underlying molecular mechanisms remain unknown.

METHODS

miRNA microarray analysis was used to determine the expression profiling of EC fresh tissues. qRT-PCR was performed to screen miR-205-5p expression in EC tissues. The roles of miR-205-5p and its candidate target gene, angiopoietin-2 (ANGPT2), in endometriosis progression were confirmed on the basis of both in vitro and in vivo systems. miR-205-5p and ANGPT2 expression were measured by in situ hybridization and immunochemistry, and their clinical significance was statistically analysed.

RESULTS

miR-205-5p was screened as a novel suppressor of endometriosis through primary ectopic endometrial stromal cell migration, invasion, and apoptosis assay in vitro, along with endometrial-like xenograft growth and apoptosis in vivo. In addition, ANGPT2 was identified as a direct target of miR-205-5p through bioinformatic target prediction and luciferase reporter assay. Re-expression and knockdown of ANGPT2 could respectively rescue and simulate the effects induced by miR-205-5p. Importantly, the miR-205-5p-ANGPT2 axis was found to activate the ERK/AKT pathway in endometriosis. Finally, miR-205-5p and ANGPT2 expression were closely correlated with the endometriosis severity.

CONCLUSION

The newly identified miR-205-5p-ANGPT2-AKT/ERK axis illustrates the molecular mechanism of endometriosis progression and may represent a novel diagnostic biomarker and therapeutic target for disease treatment.

Efficacy of a Bispecific Antibody Co-Targeting VEGFA and Ang-2 in Combination with Chemotherapy in a Chemoresistant Colorectal Carcinoma Xenograft Model

Vascular endothelial growth factor (VEGF) inhibition by the addition of bevacizumab to the chemotherapy regimen of metastatic colorectal cancer leads to an improved outcome. However, anti-angiogenic tumor therapy targeting a single factor may be limited by complementary mechanisms. Angiopoietin-2 (Ang-2, ANGPT2) is another important factor that cooperates with VEGF to drive tumor angiogenesis. It was shown that high Ang-2 levels are associated with a poor clinical outcome of colorectal cancer patients treated with bevacizumab-containing therapy. Therefore, combined inhibition of VEGF and Ang-2 was supposed to improve anti-angiogenic therapy. Here, we evaluated the efficacy of a bispecific antibody (CrossMab) co-targeting VEGF and Ang-2 in combination with chemotherapy in a chemoresistant colorectal carcinoma model. Antitumor activity was evaluated in athymic nude mice bearing subcutaneous DLD1 xenograft tumors and treated with anti-VEGF (B20), anti-Ang-2 (LC06) and anti-VEGF/Ang-2 (CrossMab) antibodies. Chemotherapy consisted of 5-FU and irinotecan. Resected tumors were analyzed immunohistochemically. First, an impact of targeting each single factor but also a clear advantage of co-targeting both factors could be demonstrated. Accordingly, tumor tissue showed strong staining for VEGF and Ang-2. Chemotherapy alone was less effective. Efficient tumor growth inhibition could be achieved by treatment with anti-VEGF/chemotherapy, single CrossMab and CrossMab/chemotherapy, which resulted in 3 out of 10, 6 out of 10 and 10 out of 10 complete responses, respectively, during seven weeks. Complete retarded tumors were characterized by massive intratumoral necrosis surrounded by layers of vital tumor cells and connective tissue with CD31-positive vessels at the periphery. In some cases, a distinct feature known as vessel co-option could be observed. In conclusion, the data from this model clearly support the strategy of co-targeting VEGF and Ang-2 and further demonstrate the beneficial impact of co-treatment with chemotherapy. The clear superiority of the CrossMab-containing regimen compared to clinical standard anti-VEGF/chemotherapy warrants further analyses in other models.

Targeting β1-integrin inhibits vascular leakage in endotoxemia

Compromised vascular integrity is associated with capillary leakage in sepsis, but effective therapies stabilizing the vasculature are lacking. Here, we show that targeting β1-integrin in vivo with inhibitory antibodies or deletion of a single allele of endothelial β1-integrin inhibits lipopolysaccharide (LPS)-induced vascular leakage in murine endotoxemia. The inflammatory agents IL-1β, thrombin, and LPS induced changes in endothelial cell–extracellular matrix (ECM) adhesion via β1-integrin, angiopoietin-2, and the adapter protein tensin-1, leading to increased endothelial cell contractility and permeability. These results indicate that β1-integrin actively promotes vascular leakage and that targeting β1-integrin signaling could be a novel means of achieving vascular stabilization in pathological vascular leak.

Loss of endothelial integrity promotes capillary leakage in numerous diseases, including sepsis, but there are no effective therapies for preserving endothelial barrier function. Angiopoietin-2 (ANGPT2) is a context-dependent regulator of vascular leakage that signals via both endothelial TEK receptor tyrosine kinase (TIE2) and integrins. Here, we show that antibodies against β1-integrin decrease LPS-induced vascular leakage in murine endotoxemia, as either a preventative or an intervention therapy. β1-integrin inhibiting antibodies bound to the vascular endothelium in vivo improved the integrity of endothelial cell–cell junctions and protected mice from endotoxemia-associated cardiac failure, without affecting endothelial inflammation, serum proinflammatory cytokine levels, or TIE receptor signaling. Moreover, conditional deletion of a single allele of endothelial β1-integrin protected mice from LPS-induced vascular leakage. In endothelial monolayers, the inflammatory agents thrombin, lipopolysaccharide (LPS), and IL-1β decreased junctional vascular endothelial (VE)-cadherin and induced actin stress fibers via β1- and α5-integrins and ANGPT2. Additionally, β1-integrin inhibiting antibodies prevented inflammation-induced endothelial cell contractility and monolayer permeability. Mechanistically, the inflammatory agents stimulated ANGPT2-dependent translocation of α5β1-integrin into tensin-1–positive fibrillar adhesions, which destabilized the endothelial monolayer. Thus, β1-integrin promotes endothelial barrier disruption during inflammation, and targeting β1-integrin signaling could serve as a novel means of blocking pathological vascular leak.

Demethylation of the MIR145 promoter suppresses migration and invasion in breast cancer

miR-145 has been implicated in the progression of breast cancer. Here, we report that its expression is decreased in breast cancer specimens and cell lines and that this low level of expression is associated with DNA methylation of its gene, MIR145. Methylation of MIR145 has previously been correlated with cell migration and invasion, both in vivo and in vitro. We found that demethylation of MIR145 reactivates miR-145 and contributes to the anti-cancer properties of 5-aza-2'-deoxyazacytidine (5-AzaC). Therefore, miR-145 is a potentially valuable biomarker for breast cancer.

MCPH1 maintains long-term epigenetic silencing of ANGPT2 in chronic lymphocytic leukemia

The microcephalin gene (MCPH1) [also known as inhibitor of human telomerase reverse transcriptase (hTERT) expression] is a tumor suppressor gene that is functionally involved in the DNA damage response. Angiopoietin 2 (ANGPT2) is a crucial factor regulating tumor angiopoiesis. Deregulation of angiogenesis is one of the hallmarks of many cancers, including chronic lymphocytic leukemia (CLL). In CLL, ANGPT2 is a well-studied potential prognostic marker. As MCPH1 overlaps with the ANGPT2 transcription unit on the same chromosome but in the opposite orientation, we wanted to study the functional role of MCPH1 in regulation of ANGPT2 in CLL. The mRNA expression levels of MCPH1 and ANGPT2, including the MCPH1 target gene hTERT, showed significant differences between two prognostic groups, i.e. IGHV-mutated and IGHV-unmutated (P = 0.007 for MCPH1, P = 0.0002 for ANGPT2, and P = 0.00001 for hTERT), in which the expression level of MCPH1 was inversely correlated with the expression levels of hTERT and ANGPT2. Downregulation of MCPH1 resulted in upregulation of ANGPT2, accompanied by loss of its promoter methylation. Using chromatin immunoprecipitation and coimmunoprecipitation assays, we found that MCPH1 binds to the ANGPT2 promoter and recruits DNA methyltransferases, thereby silencing ANGPT2. Thus, our data suggest a novel function for MCPH1 in regulating and maintaining ANGPT2 silencing in CLL through regulation of promoter DNA methylation.

ANGPT2 promoter methylation is strongly associated with gene expression and prognosis in chronic lymphocytic leukemia

Increasing evidence suggests a key role for angiopoietin-2 (ANGPT2) in influencing the aggressiveness of chronic lymphocytic leukemia (CLL). In the presence of vascular endothelial growth factor (VEGF), ANGPT2 causes vessel destabilization leading to neoangiogenesis. Accordingly, high expression levels of ANGPT2 and high degree of angiogenesis have consistently been associated with poor prognosis in CLL; however, the molecular mechanisms behind the variability in ANGPT2 expression are still to be discovered. Here, for the first time, we investigated the DNA methylation status of the ANGPT2 promoter in a large CLL cohort (n = 88) using pyrosequencing and correlated methylation data with ANGPT2 expression levels, prognostic factors and outcome. Importantly, methylation levels of the ANGPT2 gene correlated inversely with its mRNA expression levels (p<0.001). Moreover, low ANGPT2 methylation status was highly associated with adverse prognostic markers, shorter time to first treatment and overall survival. Finally, treatment with methyl inhibitors induced re-expression of ANGPT2 in two B-cell lymphoma cell lines, underscoring the importance of DNA methylation in regulating transcriptional silencing of this gene. In conclusion, we believe that the known variability in ANGPT2 expression among CLL patients could be explained by differential promoter DNA methylation and that low methylation levels of the ANGPT2 promoter have an adverse prognostic impact in CLL.