Gene regulation of a novel angiogenesis inhibitor, vasohibin, in endothelial cells

Vasohibin-1 and -2 in pulmonary lymphangioleiomyomatosis (LAM) cells associated with angiogenic and prognostic factors

Lymphangioleiomyomatosis (LAM) is a rare pulmonary neoplasm, clinically associated with dyspnea and respiratory failure. Current therapeutic modalities do not necessarily reach satisfactory outcome and novel therapeutic approaches are currently warranted. Therefore, in this study, we focused on vasohibin-1 (VASH1) and -2 (VASH2); VASH1 terminated and VASH2 promoted angiogenesis. In addition, both VASH1/2 were reported to influence the progression of various human malignancies. We first performed hierarchical clustering analysis to attempt to classify 36 LAM cases into three different clusters according to immunoreactivity of VASH1/2 and other angiogenic and prognostic factors of LAM; VEGFR1/2/3, p-mTOR, p-S6, p-4EBP, ERα, PgR, MMP2, and MMP9. The cluster harboring higher angiogenic factors had higher VASH1/2 status. VASH1 was significantly positively correlated with VEGFR2, MMP9, and p-mTOR (p-value <0.05), and VASH2 with both angiogenic and prognostic factors including VEGFR1, PgR, MMP9, p-mTOR, p-S6, and p-4EBP (p-value <0.05). Subsequent PCR array of angiogenic genes demonstrated that high VASH1 mRNA was significantly positively associated with the status of SPHK1 and TYPM, lower EGF and EFNB2 (p-value <0.05), and high VASH2 mRNA negatively with MMP2 (p-value <0.05). VASH1 was considered to be up-regulated by activation of angiogenesis, whereas VASH2 could influence the angiogenesis and progression of LAM.

Vasohibin-1 expression as a biomarker of aggressive nature in ductal adenocarcinoma of the prostate: a retrospective cohort study at two centres in Japan

OBJECTIVES

Vasohibin-1 (VASH1) is an endogenous angiogenesis regulator expressed in activated vascular endothelial cells. We previously reported that high VASH1 expression is a predictor of progression in acinar adenocarcinoma of the prostate. In this study, we evaluated the characteristics of ductal adenocarcinoma of the prostate by comparing the level of VASH1 expression between ductal and acinar adenocarcinoma specimens.

DESIGN AND SETTING

A retrospective cohort study at two centres in Japan.

PARTICIPANTS

Among the 1495 patients who underwent radical prostatectomy or transurethral resection for the past 15 years, a total of 14 patients diagnosed with ductal adenocarcinoma and 20 patients diagnosed with acinar adenocarcinoma with a Gleason score of 4+4 were included.

INTERVENTIONS

We immunohistochemically examined the CD34 expression as the microvessel density (MVD) and activated endothelial cells as the VASH1 density (vessels per mm²).

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was the association of MVD and VASH1 density between ductal and acinar adenocarcinoma, and the secondary outcome was their oncological outcomes.

RESULTS

Nine patients (64.3%) with ductal adenocarcinoma were diagnosed at an advanced clinical stage, and five patients (35.7%) died from cancer during a median follow-up of 56.0 months. The VASH1 densities (mean±SD) in ductal and acinar adenocarcinoma were 45.1±18.5 vs 16.1±21.0 (p<0.001), respectively, while the MVD (mean±SD) in ductal and acinar adenocarcinoma were 65.3±21.9 vs 80.8±60.7 (p=0.666), respectively. The 5-year cancer-specific survival rates for high and low VASH1 expression were 70.0% and 100.0% (p=0.006), respectively. High VASH1 expression and a diagnosis of ductal adenocarcinoma were significant predictors of cancer-specific survival.

CONCLUSIONS

Ductal adenocarcinoma was more aggressive and had higher VASH1 expression than acinar adenocarcinoma, although MVD was equivalent. These results indicate that VASH1 expression may serve as a novel biomarker for the aggressive nature of ductal adenocarcinoma.

circASS1 overexpression inhibits the proliferation, invasion and migration of colorectal cancer cells by regulating the miR-1269a/VASH1 axis

Colorectal cancer (CRC), the third most common cancer worldwide, poses a threat to human life. However, its underlying mechanism is unclear and no satisfactory treatment is available. The present study aimed to investigate the role of circular RNA argininosuccinate synthase 1 (circASS1) in CRC cells and tissues to identify the potential mechanism underlying the pathogenesis of CRC. The expression of circASS1 in CRC cells and tissues was determined by reverse transcription-quantitative PCR. Following circASS1 overexpression in HT29 cells, cell viability, colony formation and apoptosis were measured using MTT, colony formation and TUNEL assays, respectively. Cell invasion and migration were also assessed. After confirming the associations among circASS1, microRNA (miR)-1269a and vasohibin 1 (VASH1), the characteristics of the HT29 cell line were assessed by performing the aforementioned assays. circASS1 expression was decreased in CRC cells and tissues, and circASS1 overexpression suppressed CRC cell proliferation, invasion and migration. circASS1 adsorbed miR-1269a and regulated its expression, and VASH1 was a target protein of miR-1269a. circASS1 overexpression decreased cell proliferation, invasion and migration, but enhanced cell apoptosis in HT29 cells, which was reversed by co-transfection with miR-1269a mimic or short hairpin RNA-VASH1. In conclusion, circASS1 overexpression inhibited CRC cell proliferation, invasion and migration by regulating miR-1269a/VASH1, which indicated a potential molecular mechanism underlying the pathogenesis of CRC.

Vasohibin 1, a clinically relevant biomarker, contributes to pre-eclampsia

BACKGROUND

Pre-eclampsia is a leading health threat for pregnant women which is characterised by hypertension and proteinuria. The detailed mechanism is elusive and no effective therapy is available. Predictive biomarkers are needed for accurate diagnosis. Vasohibin-1 (VASH1) is an intrinsic inhibitor of angiogenesis induced by angiogenic factors in endothelial cells. This study aimed to evaluate the role of VASH1 as a useful biomarker for pre-eclampsia.

METHODS

VASH1 level was examined by ELISA and immunoblotting assay in the serum and placental samples from healthy pregnant women and pre-eclampsia patients. Cellular assay was performed to assess cell migration and invasion with different levels of VASH1. The level of VASH1 was measured under different oxygen conditions by qPCR.

RESULTS

VASH1 was highly expressed in the serum and placenta of pre-eclampsia patients. Overexpression of VASH1 led to attenuated cell migration and invasion ability and reduced levels of matrix metallopeptidase 2 and 9. VASH1 was significantly induced in primary human trophoblast cells and placental explants under hypoxic condition in hypoxia-inducible factor 1 alpha-dependent manner.

CONCLUSION

Our study suggested that VASH1 could be used as a potentially novel biomarker for pre-eclampsia and its level may positively correlate with the disease status.

VEZF1-guanine quadruplex DNA interaction regulates alternative polyadenylation and detyrosinase activity of VASH1

Vascular endothelial zinc finger 1 (VEZF1) plays important roles in endothelial lineage definition and angiogenesis. Vasohibins 1 and 2 (VASH1 and VASH2) can form heterodimers with small vasohibin-binding protein (SVBP) and were recently shown to regulate angiogenesis by acting as tubulin detyrosinases. Here, we showed that VEZF1 binds directly with DNA guanine quadruplex (G quadruplex, G4) structures in vitro and in cells, which modulates the levels of the two isoforms of VASH1 mRNA. Disruption of this interaction, through genetic depletion of VEZF1 or treatment of cells with G4-stabilizing small molecules, led to increased production of the long over short isoform of VASH1 (i.e. VASH1A and VASH1B, respectively) mRNA and elevated tubulin detyrosinase activity in cells. Moreover, disruption of VEZF1-G4 interactions in human umbilical vein endothelial cells resulted in diminished angiogenesis. These results suggest that the interaction between VEZF1 and G4 structures assumes a crucial role in angiogenesis, which occurs through regulating the relative levels of the two isoforms of VASH1 mRNA and the detyrosinase activity of the VASH1-SVBP complex. Together, our work revealed VEZF1 as a G4-binding protein, identified a novel regulatory mechanism for tubulin detyrosinase, and illustrated that the VEZF1- and VASH1-mediated angiogenesis pathways are functionally connected.

VASH-1 Regulates Oxidative Stress and Fibrosis in Diabetic Kidney Disease via SIRT1/HIF1α and TGFβ1/Smad3 Signaling Pathways

Aims: To investigate the role of Vasohibin-1 (VASH-1), silence information adjustment factor 2-related enzyme 1 (SIRT1)/hypoxic-inducible factor 1α (HIF1α) and transforming growth factor-β1 (TGFβ1) /Smad3 signaling pathways in oxidative stress and fibrosis of diabetic kidney disease (DKD).

Materials and Methods: A diabetic rat model was established in vivo and rat mesangial cells (RMCs) were cultured in vitro with high glucose via transfection with Vash1 small interfering RNA (siRNA), Hif1a siRNA, Sirt1 siRNA and TGFβ1/Smad3 pathway inhibitor (SB431542). Renal histology was used to detect renal changes. Real-time PCR and western blot were used to analyze the expression of VASH-1, SIRT1, HIF1α, TGFβ1, Smad3, vascular endothelial growth factor (VEGF), connective tissue growth factor (CTGF) and fibronectin (FN). Expression levels of tumor necrosis factor-α (TNFα), TGFβ1, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA) in rat tissues and cell culture supernatant were detected by ELISA and chemiluminescence assay, while cell proliferation was detected by CCK-8.

Results: The level of VASH-1 in renal tissues of diabetic rats was decreased, while both high glucose and Vash1 siRNA inhibited the expression of VASH-1 and SIRT1, increased the levels of HIF1α, TGFβ1, and Smad3 in RMCs, thus up-regulating oxidative stress and fibrosis factors, and abnormally increasing cell proliferation activity (P < 0.05). However, inhibition of SIRT1/HIF1α signaling pathway only reduced TGFβ1 and Smad3 (P < 0.05), while VASH-1 remained unchanged (P > 0.05).

Conclusion: VASH-1 was under-expressed in renal tissues of diabetic rats and regulated the pathological process of oxidative stress and fibrosis in DKD via downstream SIRT1/HIF1α and TGFβ1/Smad3 signaling pathways.

A review on vasohibin and ocular neovascularization

Ischemic and neovascular disease is one of the most difficult ocular diseases to deal with nowadays. Redundancy, poor visual acuity and decreased life quality are bothering patients and ophthalmologists for decades. After vascular endothelial growth factor (VEGF) was found to be a primary factor in promoting retinal angiogenesis, intravitreal injection of anti-VEGF drugs has been the first-line treatment. Whereas, some patients are refractory to this therapy and problems of economic burden, local complications and adverse effects promote researches into other possible targets. The vasohibin (VASH) family is a newly-investigated factor in modulating ocular angiogenesis. The family includes VASH1 and VASH2, which show opposite effects of inhibiting and accelerating angiogenesis respectively. Positive results have been reported in cellular and animal experiments. With further researches, it can be a promising future target of treating ocular neovascular diseases.

Kaempferol protects retinal ganglion ceils from high-glucose-induced injury by regulating vasohibin-1

Kaempferol is a medicinal flavonol derived from the roots of Kaempferia galanga L. Kaempferol can affect cell survival, apoptosis, and anti-oxidation, though its role and underlying mechanism in retinal ganglion cells with high-glucose injury remains unclear. In this study, we explored kaempferol's role in high-glucose injury in cells from the retinal ganglion cell (RGC) line. RGC cells were isolated and then cultured in high glucose (55 mmol/L) for 0 h, 12 h, 24 h, 48 h, or 72 h, and results showed decreased cell viability at 48 h and 72 h. We treated RGC cells with different concentrations of kaempferol (0 μmol/L, 20 μmol/L, 40 μmol/L, 60 μmol/L, 80 μmol/L, or 100 μmol/L) and high-glucose (55 mmol/L) for 48 h. The data indicated inhibited lactate dehydrogenase leakage, apoptosis, caspase-3 activity, and reactive oxygen species (ROS) levels. Moreover, whereas cell viability increased in RGC cells that were incubated with kaempferol (60 μmol/L, 80 μmol/L, or 100 μmol/L) and glucose (55 mmol/L), compared with glucose alone. Kaempferol (60 μmol/L) elevated ERK phosphorylation and vasohibin-1 (VASH1) expression, and inhibition of ERK phosphorylation reversed the effect of kaempferol (60 μmol/L) on VASH1 expression in RGC cells with high-glucose injury. Additionally, interference of VASH1 by VASH1 siRNA markedly reversed the effects of kaempferol (60 μmol/L) on cell viability, caspase-3 activity, and ROS levels in RGC cells with high glucose injury. Taken together, the results suggest that kaempferol protected retinal ganglion cells from high-glucose-induced injury via ERK and VASH1 signaling.

Expression levels of serum vasohibin-1 and other biomarkers in type 2 diabetes mellitus patients with different urinary albumin to creatinine ratios

AIM

To determine the serum levels of vasohibin (VASH)-1 and other biomarkers in type 2 diabetes mellitus (T2DM) patients with different urinary albumin to creatinine ratios (UACR), and correlate VASH-1 expression with the inflammation and fibrosis in diabetic kidney disease (DKD).

METHODS

A total of 697 T2DM patients were stratified into four groups: N-UAlb (UACR <30 mg/g with normal blood pressure, n = 144), M-UAlb (UACR 30-300 mg/g with normal blood pressure, n = 143), L-UAlb (UACR >300 mg/g with normal blood pressure, n = 126), and L-UAlb+HP (UACR >300 mg/g with hypertension, n = 134). In addition, 150 healthy subjects were included as normal controls (NC). In addition to recording the age and duration of diabetes, the serum levels of VASH-1, silent information regulator factor 2-related enzyme 1 (sirtuin-1, SIRT1), hypoxia inducible factor 1α (HIF1α), vascular endothelial growth factor (VEGF), C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), and the erythrocyte sedimentation rate (ESR) were measured. Clinical parameters related to UACR and VASH-1 were analyzed by one-way ANOVA, Pearson correlation and ridge regression analysis.

RESULTS

The UACR, VASH-1, glycosylated hemoglobin (HbA1c), ESR, CRP, VEGF, HIF1α, TNF-α and TGF-β1 levels in all patient groups were significantly higher, and SIRT1 levels were lower compared to the NC group. Pearson correlation analysis showed that UACR and VASH-1 levels were positively correlated with HbA1c, ESR, CRP, VEGF, HIF1α, TNF-α and TGF-β1, and negatively with SIRT1. Ridge regression analysis showed that every serological marker was an independent factor affecting UACR.

CONCLUSION

Serum VASH-1 may be associated with the expression of renal inflammation and fibrosis-related factors, and have a potential connection with DKD.

Expression of vasohibin-1 and -2 predicts poor prognosis among patients with squamous cell carcinoma of the esophagus

Vasohibin (VASH) -1 and -2 are novel angiogenic regulators. The aim of the present study was to assess the prognostic values of VASH1 expression and VASH2 expression in esophageal squamous cell carcinoma (ESCC). A total of 209 patients with ESCC were investigated. Resected tumor specimens were immunostained using anti-CD34 antibody, anti-VASH1 antibody and anti-VASH2 antibody. The ratio of the microvessels density and the VASH1 density as the VASH1-positive ratio were defined and the patients were divided into two groups (a high VASH1 group and a low VASH1 group) according to the average value. The patients were also divided into two groups (a high VASH2 group and a low VASH2 group) according to VASH2 expression upon immunostaining. The clinical outcomes of these two groups were then evaluated. The high VASH1 group contained 106 patients (50.7%). The high VASH2 group contained 48 patients (23.0%). Long-term survival was significantly poorer in the high VASH1 group compared with that in the low VASH1 group. A slight correlation between VASH1 expression and VASH2 expression was observed. The low VASH1/low VASH2 group had a better prognosis than the other three groups with different combinations of VASH1 and VASH2 expression levels. The present study showed that high VASH1 expression and high VASH2 expression may be novel independent predictors of a poor prognosis in patients with ESCC and that a slight correlation between VASH1 and VASH2 expression existed. The present findings suggest that combined evaluation of VASH1 and VASH2 expression should provide an improved understanding of their clinicopathological features.

Double-Face of Vasohibin-1 for the Maintenance of Vascular Homeostasis and Healthy Longevity

The structural and functional integrity of endothelium is essential for the maintenance of vascular health. Vasohibin-1 (VASH1), originally isolated as an endothelium-derived angiogenesis inhibitor, has another function to promote stress tolerance of endothelial cells (ECs), and these functions are critical for the maintenance of vascular homeostasis preventing both pathological angiogenesis and stress-induced vascular diseases. The expression of VASH1 is downregulated during replicative senescence of ECs by the alteration of microRNA expression, and this age-associated downregulation of VASH1 might be a risk of deterioration of vascular homeostasis and age-related vascular diseases. Contrary to this expectation, the lack of Vash1 gene in mice exhibited healthy longevity. Thus, VASH1 has double-face for the maintenance of vascular homeostasis and healthy longevity. This feature of VASH1 and its mechanism will be described in this mini review.

The peritoneal "soil" for a cancerous "seed": a comprehensive review of the pathogenesis of intraperitoneal cancer metastases

Various types of tumors, particularly those originating from the ovary and gastrointestinal tract, display a strong predilection for the peritoneal cavity as the site of metastasis. The intraperitoneal spread of a malignancy is orchestrated by a reciprocal interplay between invading cancer cells and resident normal peritoneal cells. In this review, we address the current state-of-art regarding colonization of the peritoneal cavity by ovarian, colorectal, pancreatic, and gastric tumors. Particular attention is paid to the pro-tumoral role of various kinds of peritoneal cells, including mesothelial cells, fibroblasts, adipocytes, macrophages, the vascular endothelium, and hospicells. Anatomo-histological considerations on the pro-metastatic environment of the peritoneal cavity are presented in the broader context of organ-specific development of distal metastases in accordance with Paget's "seed and soil" theory of tumorigenesis. The activity of normal peritoneal cells during pivotal elements of cancer progression, i.e., adhesion, migration, invasion, proliferation, EMT, and angiogenesis, is discussed from the perspective of well-defined general knowledge on a hospitable tumor microenvironment created by the cellular elements of reactive stroma, such as cancer-associated fibroblasts and macrophages. Finally, the paper addresses the unique features of the peritoneal cavity that predispose this body compartment to be a niche for cancer metastases, presents issues that are topics of an ongoing debate, and points to areas that still require further in-depth investigations.

Vasohibin-1 as a novel microenvironmental biomarker for patient risk reclassification in low-risk prostate cancer

Background

We previously reported high expression of vasohibin-1 (VASH1), which is specifically expressed in activated vascular endothelial cells, was a prognostic indicator of disease progression in prostate cancer. The aim of this study was to assess whether VASH1 expression at the area of normal prostatic tissue as well as that of intratumoral tissue could reflect the grade of malignancy of prostate cancer.

Results

Pathological upgrade of Gleason Score ≥7 by radical prostatectomy was observed in 48 patients (upgraded group). The median VASH1 densities of the intratumoral and normal areas were 9.7 ± 9.5 and 13.3 ± 11.8, respectively, and the median MVDs were 58.6 ± 20.3 and 64.1 ± 23.5, respectively. We detected a strong positive correlation with each other for both VASH1 density (ρ = 0.589, p < 0.001) and MVD (ρ = 0.342, p < 0.001). VASH1 density was significantly higher in the upgreaded group than in the non-upgraded group regardless of prostatic location (intratumoral area: p < 0.001, normal area: p < 0.001).

Conclusions

Even if the tumor volume was low in biopsy samples, VASH1 density reflected the grade of malignancy throughout the prostate. These results suggested that VASH1 expression could be a novel microenvironmental biomarker for patient risk reclassification in low-risk prostate cancer.

Materials and Methods

Among the 1177 patients who underwent radical prostatectomy, 104 patients diagnosed with Gleason Score ≤6 and positive cores ≤3 were included. We immunohistochemically examined the microvessels positive for anti-CD34 as microvessel density (MVD), and those with activated endothelial cells as VASH1 density using prostatic biopsy samples, and evaluated the association between their expressions and clinicopathological findings.

The roles of vasohibin and its family members: Beyond angiogenesis modulators

Vasohibin-1 is an intrinsic angiogenesis inhibitor, and is expressed in endothelial cells via induction by pro-angiogenesis factors. It is known to inhibit several processes of angiogenesis, with different mechanisms from extrinsic angiogenesis inhibitors. Vasohibin-2 is mainly expressed by mononuclear cells which have been mobilized from bone marrow. It not only promotes angiogenesis, but also modulates the releases of FGF-2 and VEGF, which are the two major inducers for vasohibin1. Hypoxic environment induces the expression of hypoxia-inducible Factor 1α with a result of VEGF release nearly in all tumor cell lines and tissues. However, it has been observed that hypoxia reduces the inducible effects of VEGF on vasohibin, which indicates that a complicated mechanism exists in the angiogenesis. Vasohibin and its family members play important roles in both the physiological and pathological procedures, in contrary but complementary patterns. Furthermore, human aortic smooth muscle cells and fibroblast have also been detected to express vasohibin on a moderate to weak scale range. Recently, the results of an increasing number of studies in vivo have shown that vasohibin can also be detected in several cancers, and is associated with micro-vessel densities, histology grades, invasions, poor clinical features, metastasis, and dissemination in abdominal cavities, as well as EMT. In more recent reports, it has been confirmed that, along with being angiogenesis regulators, a variety of other roles have been associated with this family. The focus of this study was the upstream regulatory mechanisms of vasohibin expressions, and their role in regard to the downstream target proteins of vasohibin, especially in carcinoma. Vasohibin is considered to be an original angiogenesis inhibitor, and has a much broader significance in pathological processes. It can be taken as an independent prognostic factor, as well as a potential strategy for cancer therapy programs.

Increased vasohibin-1 expression is associated with metastasis and poor prognosis of renal cell carcinoma patients

The microvascular density detected by markers of endothelial cells (ECs), such as CD31 and CD34, is considered to be a biomarker for angiogenesis, and it is generally associated with the malignant potential of solid tumors. However, there is a conflicting relationship between the microvascular density and prognosis in clear-cell renal cell carcinoma (ccRCC) patients. It may be explained by the suggestion that the microvascular density cannot fully reflect the angiogenic activity in ccRCC, as the markers of ECs are expressed by both quiescent and activated ECs. To investigate the real angiogenic activity, we examined vasohibin-1 (VASH1), a recently identified regulator of angiogenesis, which was demonstrated to be specifically expressed by ECs of newly formed blood vessels. Expression of VASH1 and CD34 were immunohistochemically examined in 116 primary untreated ccRCCs, 10 metastatic untreated ccRCCs, and 9 metastatic ccRCCs treated with sunitinib. ECs in the tumor microvessels were sporadically immunostained for VASH1, although no VASH1 staining was observed in the non-neoplastic renal tissues. CD34 was ubiquitously expressed by all ECs in both ccRCC and non-neoplastic renal tissues. Multivariate Cox analysis indicated that an elevated VASH1 density, but not microvascular density, was a significant and independent predictor of overall survival (odds ratio, 7.71; P=0.003). The microvascular density was significantly decreased in the sunitinib-treated metastases compared with untreated tumors (P=0.001). On the other hand, the VASH1 density was significantly higher in the metastatic ccRCCs treated with sunitinib compared with non-treated ones (P=0.010), indicating that VASH1 may be associated with the resistance of ECs to sunitinib treatment. Thus, VASH1 expression may reflect the actual activity of angiogenesis, and VASH1 can serve as a new prognostic and predictive biomarker in patients with ccRCC.

MicroRNA-4530 promotes angiogenesis by targeting VASH1 in breast carcinoma cells

The results of our previous study revealed that microRNA (miRNA/miR)-4530 was upregulated in the serum of patients with diabetic retinopathy. The TargetScan miRNA database was used to identify potential targets of miR-4530 and vasohibin-1 (VASH1) was predicted as one of the targets. The results of our previous study demonstrated that miR-4530 was able to promote angiogenesis in human umbilical vein endothelial cells. Therefore, suppressing miR-4530 may be a potentially novel approach towards inhibiting tumor angiogenesis. The present study aimed to investigate the function of miR-4530 and determine whether miR-4530 was able to regulate angiogenesis in breast carcinoma cells by targeting VASH1. MDA-MB-231 and MCF-7 cells were transfected with miR-4530 precursor, anti-miR-4530 and empty vector plasmids. The expression levels of miRNA and mRNA were detected using the reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The expression levels of protein were detected using western blotting. Dual-luciferase reporter assays were used to identify the target of miR-4530. Furthermore, cell proliferation, cell cycle, apoptosis and tube formation assays were used to investigate the function of miR-4530 in vitro. Nude mice were used in a subcutaneous tumor model in vivo study. The results of the present study demonstrated that miR-4530 significantly suppressed proliferation and promoted apoptosis of breast carcinoma cells. In addition, miR-4530 expression promoted angiogenesis in vitro. Results from the western blotting and RT-qPCR revealed that VASH1 was significantly downregulated by miR-4530 in breast carcinoma cells. The results of the present study suggest that miR-4530 promotes angiogenesis, inhibits proliferation and induces apoptosis in breast carcinoma cells by suppressing the expression of VASH1.

Control of angiogenesis and host response by modulating the cell adhesion properties of an Elastin-Like Recombinamer-based hydrogel

The control of the in vivo vascularization of engineered tissue substitutes is essential in order to obtain either a rapid induction or a complete inhibition of the process (e.g. in muscles and hyaline-cartilage, respectively). Among the several polymers available, Elastin-Like Recombinamers (ELR)-based hydrogel stands out as a promising material for tissue engineering thanks to its viscoelastic properties, non-toxicity, and non-immunogenicity. In this study, we hypothesized that varying the cell adhesion properties of ELR-hydrogels could modulate the high angiogenic potential of adipose tissue-derived stromal vascular fraction (SVF) cells, predominantly composed of endothelial/mural and mesenchymal cells. Human SVF cells, embedded in RGD-REDV-bioactivated or unmodified ELR-hydrogels, were implanted in rat subcutaneous pockets either immediately or upon 5-day-culture in perfusion-bioreactors. Perfusion-based culture enhanced the endothelial cell cord-like-organization and the release of pro-angiogenic factors in functionalized constructs. While in vivo vascularization and host cell infiltration within the bioactivated gels were highly enhanced, the two processes were strongly inhibited in non-functionalized SVF-based hydrogels up to 28 days. ELR-based hydrogels showed a great potential to determine the successful integration of engineered substitutes thanks to their capacity to finely control the angiogenic/inflammation process at the recipient site, even in presence of SVF cells.

Domain architecture of vasohibins required for their chaperone-dependent unconventional extracellular release

Vasohibins (VASH1 and VASH2) are recently identified regulators of angiogenesis and cancer cell functions. They are secreted proteins without any classical secretion signal sequences, and are thought to be secreted instead via an unconventional protein secretion (UPS) pathway in a small vasohibin-binding protein (SVBP)-dependent manner. However, the precise mechanism of SVBP-dependent UPS is poorly understood. In this study, we identified a novel UPS regulatory system in which essential domain architecture (VASH-PS) of VASHs, comprising regions VASH1_91-180 and VASH2_80-169 , regulate the cytosolic punctate structure formation in the absence of SVBP. We also demonstrate that SVBP form a complex with VASH1 through the VASH1_274-282 (SIa), VASH1_139-144 (SIb), and VASH1_133-137 (SIc), leading to the dispersion in the cytosol and extracellular release of VASH1. The amino acid sequences of VASH-SIa and VASH-PS, containing SIb and SIc, are highly conserved among VASH family members in vertebrates, suggesting that SVBP-dependent UPS may be common within the VASH family. This novel UPS regulatory system may open up new avenues for understanding fundamental protein secretion in vertebrates.

Expression pattern of HIF1alpha and vasohibins during follicle maturation and corpus luteum function in the bovine ovary

The aim of this study was to characterize expression patterns of hypoxia-inducible factor-1alpha (HIF1A) and vasohibin family members (VASH1 and VASH2) during different stages of ovarian function in cow. Experiment 1: Antral follicle classification occurred by follicle size and estradiol-17beta (E2) concentration in the follicular fluid into 5 groups (<0.5, 0.5-5, 5-40, 40-180 and >180 E2 ng/ml). Experiment 2: Corpora lutea (CL) were assigned to the following stages: days 1-2, 3-4, 5-7, 8-12, 13-16 and >18 (after regression) of oestrous cycle and of pregnancy (months 1-2, 3-4, 6-7, >8). Experiment 3: Cows on days 8-12 were injected with a prostaglandin F2alpha (PGF) analogue and CL were collected before and 0.5, 2, 4, 12, 24, 48 and 64 hr after PGF injection. Expression of mRNA was measured by qPCR, steroid hormone concentration by EIA and localization by immunohistochemistry. HIF1A mRNA expression in our study increases significantly in follicles during final maturation. The highest HIF1A mRNA expression was detected during the early luteal phase, followed by a significant decrease afterwards. In contrast, the mRNA of vasohibins in small follicle was high, followed by a continuous and significant downregulation in preovulatory follicles. The obtained results show a remarkable inverse expression and localization pattern of HIF1A and vasohibins during different stages of ovarian function in cow. These results lead to the assumption that the examined factors are involved in the local mechanisms regulating angiogenesis and that the interactions between proangiogenic (HIF1A) and antiangiogenic (vasohibins) factors impact all stages of bovine ovary function.

Vasohibin-1 suppresses colon cancer

Vasohibin-1 (VASH1) is an endogenous angiogenesis inhibitor.However, the clinical relevance of VASH1 in colon cancer and its regulations on cancer angiogenesis and cancer cell biological characteristics are still unknown. Here we showed that stromal VASH1 levels were negatively correlated with tumor size, advanced clinical stage and distant metastases in colon cancer patients. Overexpression of VASH1 in colon cancer cells induced apoptosis and senescence, inhibiting cancer cell growth and colony formation in vitro and tumor growth in vivo. In addition, knockdown of VASH1 in cancer cells promoted cell growth, adhesion and migration in vitro, and enhanced tumorigenesis and metastasis in vivo.

Distinctive role of vasohibin-1A and its splicing variant vasohibin-1B in tumor angiogenesis

Vasohibin-1 (VASH1) was isolated as a negative-feedback regulator of angiogenesis expressed in endothelial cells (ECs). There are two transcripts of VASH1, that is, the full-length VASH1A consisting of seven exons and the splicing variant VASH1B consisting of four exons. Here, we compared the effects of VASH1A and VASH1B on tumor angiogenesis. When ECs were transfected with VASH1A or VASH1B cDNAs, VASH1B transfectants, but not VASH1A ones, induced autophagic cell death of ECs. With sonoporation, the VASH1A or VASH1B gene were transfected specifically in ECs of tumor vessels in mice. Both VASH1A and VASH1B decreased tumor vessel density and inhibited tumor growth. VASH1A normalized the remaining tumor vessels, increased their rate of perfusion, decreased tumor hypoxia and enhanced the efficacy of anticancer chemotherapy, whereas VASH1B pruned tumor vessels without causing normalization, increased tumor hypoxia and tumor necrosis and did not enhance the efficacy of anticancer chemotherapy. The alternate transfection of mice with the VASH1A and VASH1B gene showed the highest effects on antitumor activity and normalization of tumor vessels. Our present findings on VASH1A and VASH1B should provide an innovative approach that would improve the efficacy of antiangiogenic cancer therapy by balancing vascular normalization and pruning.

Vasohibin-1 expression inhibits advancement of ovarian cancer producing various angiogenic factors

Vasohibin‐1 (VASH1) is a negative feedback regulator of angiogenesis, the first to be discovered, and was identified in vascular endothelial growth factor (VEGF)‐stimulated vascular endothelial cells. Vasohibin‐1 inhibits abnormal vascularization induced by various angiogenic factors including fibroblast growth factor and platelet‐derived growth factor (PDGF), in addition to VEGF. By focusing on this characteristic of VASH1, we investigated the antitumor effects of VASH1 expression on ovarian cancer cells that produce different angiogenic factors. By using a high VEGF‐producing ovarian cancer cell line, SHIN‐3, and a high PDGF‐producing ovarian cancer cell line, KOC‐2S, the cells were transfected with either a VEGF antagonist, soluble VEGF receptor‐1 (sVEGFR‐1, or sFlt‐1), or VASH1 genes to establish their respective cellular expression. The characteristics of these transfectants were compared with controls. We previously reported that the expression of sFlt‐1 inhibited tumor vascularization and growth of high VEGF‐producing ovarian cancer cells, reduced peritoneal dissemination and ascites development, and prolonged the survival time of the host. However, in the current study, the expression of sFlt‐1 had no such effect on the high PDGF‐producing ovarian cancer cells used here, whereas VASH1 expression inhibited tumor vascularization and growth, not only in high VEGF‐producing cells, but also in high PDGF‐producing cells, reduced their peritoneal dissemination and ascites, and prolonged the survival time of the host. These results suggest that VASH1 is an effective treatment for ovarian cancer cells that produce different angiogenic factors.

The angiogenesis regulator vasohibin-1 inhibits ovarian cancer growth and peritoneal dissemination and prolongs host survival

Vasohibin-1 (VASH1) is expressed in vascular endothelial cells stimulated by several angiogenic growth factors and displays autocrine activity to regulate angiogenesis via a negative feedback mechanism. In this study, we investigated the effect of VASH1 on ovarian cancer progression using VASH1-expressing ovarian cancer cells in vitro and in vivo. The growth ability of ovarian cancer cells engineered to express the VASH1 gene remained unchanged in vitro. However, we showed that VASH1 secretion by tumor cells inhibited the growth of human umbilical vein endothelial cells. Further, animal experiments showed that VASH1 expression inhibited tumor angiogenesis and growth. In a murine model of peritoneal dissemination of ovarian cancer cells, VASH1 inhibited peritoneal dissemination and ascites, resulting in significantly prolonged survival in mice. This indicates that VASH1 exerts an antitumor effect on ovarian cancer by inhibiting angiogenesis in the tumor environment. These findings suggest that a novel therapy based on VASH1 could be a useful therapeutic strategy for ovarian cancer.

Inhibition of IGF-1-Mediated Cellular Migration and Invasion by Migracin A in Ovarian Clear Cell Carcinoma Cells

Previously we isolated migracin A from a Streptomyces culture filtrate as an inhibitor of cancer cell migration. In the present research, we found that migracin A inhibited migration and invasion of ovarian clear cell carcinoma ES-2 cells. In the course of our mechanistic study, migracin A was shown to enhance vasohibin-1 expression in an angiogenesis array. We also confirmed that it increased the mRNA expression of this protein. Moreover, overexpression of vasohibin-1 lowered the migration but not the invasion of ES-2 cells. Then, we looked for another target protein employing a motility array, and found that migracin A lowered the IGF-1 expression. Knockdown of IGF-1 by siRNA decreased the migration and invasion of ES-2 cells. Migracin A also decreased Akt phosphorylation involved in the downstream signaling. Crosstalk analysis indicated that overexpression of vasohibin-1 decreased the IGF-1 expression. On the other hand, it showed no direct anticancer activity in terms of the ES-2 growth in agar. Migracin A inhibited the migration and IGF-1 expression in not only ES-2 but also another ovarian clear cell carcinoma JHOC-5 cells. In addition, it also inhibited capillary tube formation of human umbilical vein endothelial cells. Since its cytotoxicity is very low, migracin A may be a candidate for an anti-metastasis agent not exhibiting prominent toxicity.

Novel Link between Inhibition of Angiogenesis and Tolerance to Vascular Stress

The functional integrity of the vascular endothelium is an essential component required for the maintenance of vascular health, thus counteracting the onset of vascular diseases, including atherosclerosis and vascular complications of diabetes. In light of this important role, the vascular endothelium is expected to have a self-defense system. One candidate factor of such a system is vasohibin-1 (VASH1), a protein that is preferentially expressed in vascular endothelial cells (ECs). The unique features of VASH1 are its anti-angiogenic activity and ability to promote the stress tolerance and survival of ECs. This review summarizes current knowledge regarding VASH1 in terms of its roles in maintaining vascular integrity and protecting the vasculature against various forms of stress.

FLT1 genetic variation predisposes to neovascular AMD in ethnically diverse populations and alters systemic FLT1 expression

PURPOSE

Current understanding of the genetic risk factors for age-related macular degeneration (AMD) is not sufficiently predictive of the clinical course. The VEGF pathway is a key therapeutic target for treatment of neovascular AMD; however, risk attributable to genetic variation within pathway genes is unclear. We sought to identify single nucleotide polymorphisms (SNPs) associated with AMD within the VEGF pathway.

METHODS

Using a tagSNP, direct sequencing and meta-analysis approach within four ethnically diverse cohorts, we identified genetic risk present in FLT1, though not within other VEGF pathway genes KDR, VEGFA, or VASH1. We used ChIP and ELISA in functional analysis.

RESULTS

The FLT1 SNPs rs9943922, rs9508034, rs2281827, rs7324510, and rs9513115 were significantly associated with increased risk of neovascular AMD. Each association was more significant after meta-analysis than in any one of the four cohorts. All associations were novel, within noncoding regions of FLT1 that do not tag for coding variants in linkage disequilibrium. Analysis of soluble FLT1 demonstrated higher expression in unaffected individuals homozygous for the FLT1 risk alleles rs9943922 (P = 0.0086) and rs7324510 (P = 0.0057). In silico analysis suggests that these variants change predicted splice sites and RNA secondary structure, and have been identified in other neovascular pathologies. These data were supported further by murine chromatin immunoprecipitation demonstrating that FLT1 is a target of Nr2e3, a nuclear receptor gene implicated in regulating an AMD pathway.

CONCLUSIONS

Although exact variant functions are not known, these data demonstrate relevancy across ethnically diverse genetic backgrounds within our study and, therefore, hold potential for global efficacy.

Vasohibin 2 decreases the cisplatin sensitivity of hepatocarcinoma cell line by downregulating p53

Hepatocellular carcinoma (HCC) is a prevalent problem worldwide. Chemotherapy, especially cisplatin (CDDP)-based systemic chemotherapy, is the best option for advanced liver cancer. However, CDDP resistance is becoming common and hindering the clinical application of CDDP. Meanwhile, no consensus has been reached regarding the chemotherapeutic use of vasohibin 2 (VASH2), which promotes the angiogenesis and proliferation of cancer cells. In this work, a tissue microarray was used to observe VASH2 and its possible role in cancer treatment. Results showed that VASH2 was highly expressed in HCC tissues and was significantly correlated with cancer differentiation. To further investigate the efficacy and mechanism of the combination of VASH2 with anti-cancer drugs in liver cancer cells, we stably built VASH2 overexpression and knockdown cell lines. We found that VASH2 can influence the CDDP sensitivity and that the cell overexpression of VASH2 had a higher cell viability and lower apoptosis rate after CDDP exposure. We also observed that VASH2 overexpression downregulated wild-type p53, as well as suppressed the expression of the pro-apoptotic protein BCL2-associated X protein (Bax) and cleaved caspase-3 (CC-3) after treatment by CDDP. Conversely, the knockdown of VASH2 significantly inhibited these effects. In an in vivo chemosensitivity study, nude mice were subcutaneously injected with tumor cells and received CDDP treatment through intraperitoneal administration every 3 days. We found that VASH2 knockdown markedly limited the tumor growth and enhanced the CDDP toxicity and apoptosis of tumor cells. Western blot analysis revealed that tumor cells with downregulated VASH2 had a higher expression of wild-type p53, Bax, and CC-3 than control cells. Overall, our results indicated the novel roles of VASH2 in the chemoresistance of hepatocarcinoma cells to CDDP and suggested that VASH2 may be a promising anticancer target.

Generation and characterization of rabbit polyclonal antibodies against Vasohibin-2 for determination of its intracellular localization

Vasohibin-2 was recently identified as an important pro-angiogenesis factor in solid tumor and intracellular localization of its variants is important for elucidating the downstream mechanism(s) of its effects. Currently there are no reported antibodies affordable for intracellular localization. The aim of this study was to generate and characterize polyclonal antibodies against Vasohibin-2 and to determine the intracellular localization of Vasohibin-2. In this study, two polypeptides were synthesized and one prokaryotic Vasohibin-2 recombinant protein was custom-made. New Zealand rabbits were immunized with the polypeptide mixture and prokaryotic recombinant protein, respectively. The purified antibodies from the antiserum were validated by ELISA, western blotting (WB), immunofluorescence (IF), immunohistochemistry (IHC) and immunoprecipitation (IP). In order to determine intracellular localization, the cytoplasmic and nuclear proteins of the human liver cancer cell line HepG2 were isolated for the detection of Vasohibin-2 by western blotting. Vasohibin-2 cDNA, coding for 311 and 355 amino acid residues, fused with or without a DDK/V5 tag at the c-terminus, respectively, was cloned into the Lv-CMV-EGFP vector. Lentiviruses were successfully packaged. Vasohibin-2-overexpressing HepG2-VASH2 (355 amino acid residues) and HepG2-VASH2-V5 (311 amino acid residues fused with V5 tag at the c-terminus) human liver cancer cell lines were established. Approximately 1-2x106 HepG2, HepG2-VASH2 and HepG2-VASH2-V5 cells were injected subcutaneously into the flanks of BALB/c nude mice. Xenograft tumors were harvested for immunohistochemistry. HepG2 cells were transiently transfected with the Lv-CMV-EGFP vectors containing Vasohibin-2 cDNA (coding for 311/355 amino acid residues with a DDK tag at the c-terminal), followed by anti-DDK immunofluorescence. The antibodies obtained were able to detect human VASH2 successfully as applied in western blotting, IF, IHC and IP. Results from IF, IHC and WB (post cytoplasmic/nuclear protein isolation) showed a quite different intracellular localization of VASH2 protein. The VASH2 (with 355 amino acid residues) was located in the cytoplasm while VASH2 (with 311 amino acid residues) was located in the nucleus. The former was found to be a relatively low abundance protein. We successfully generated three rabbit anti-human Vasohibin-2 polyclonal antibodies which can be used for western blotting, IF, IP and IHC. These antibodies will provide a convenient tool for further studies on Vasohibin-2. This is the first study to report differences in the intracellular localization of the VASH2 protein and, hence, a new research direction on the study of VASH2.

Vasohibin-1 is identified as a master-regulator of endothelial cell apoptosis using gene network analysis

BACKGROUND

Apoptosis is a critical process in endothelial cell (EC) biology and pathology, which has been extensively studied at protein level. Numerous gene expression studies of EC apoptosis have also been performed, however few attempts have been made to use gene expression data to identify the molecular relationships and master regulators that underlie EC apoptosis. Therefore, we sought to understand these relationships by generating a Bayesian gene regulatory network (GRN) model.

RESULTS

ECs were induced to undergo apoptosis using serum withdrawal and followed over a time course in triplicate, using microarrays. When generating the GRN, this EC time course data was supplemented by a library of microarray data from EC treated with siRNAs targeting over 350 signalling molecules.The GRN model proposed Vasohibin-1 (VASH1) as one of the candidate master-regulators of EC apoptosis with numerous downstream mRNAs. To evaluate the role played by VASH1 in EC, we used siRNA to reduce the expression of VASH1. Of 10 mRNAs downstream of VASH1 in the GRN that were examined, 7 were significantly up- or down-regulated in the direction predicted by the GRN.Further supporting an important biological role of VASH1 in EC, targeted reduction of VASH1 mRNA abundance conferred resistance to serum withdrawal-induced EC death.

CONCLUSION

We have utilised Bayesian GRN modelling to identify a novel candidate master regulator of EC apoptosis. This study demonstrates how GRN technology can complement traditional methods to hypothesise the regulatory relationships that underlie important biological processes.

The vasohibin family: a novel family for angiogenesis regulation

Angiogenesis, a formation of neovessels, is regulated by the local balance between angiogenesis stimulators and inhibitors. A number of such endogenous regulators of angiogenesis have been found in the body. Recently, vasohibin-1 (VASH1) was isolated as a negative feedback regulator of angiogenesis produced by endothelial cells (ECs) and subsequently vasohibin-2 (VASH2) as a homologue of VASH1. It was then explored that VASH1 is expressed in ECs to terminate angiogenesis, whereas VASH2 is expressed in cells other than ECs to promote angiogenesis in the mouse model of angiogenesis. This review will focus on the vasohibin family members, which are novel regulators of angiogenesis.

Angiogenesis inhibitor vasohibin-1 enhances stress resistance of endothelial cells via induction of SOD2 and SIRT1

Vasohibin-1 (VASH1) is isolated as an endothelial cell (EC)-produced angiogenesis inhibitor. We questioned whether VASH1 plays any role besides angiogenesis inhibition, knocked-down or overexpressed VASH1 in ECs, and examined the changes of EC property. Knock-down of VASH1 induced premature senescence of ECs, and those ECs were easily killed by cellular stresses. In contrast, overexpression of VASH1 made ECs resistant to premature senescence and cell death caused by cellular stresses. The synthesis of VASH1 was regulated by HuR-mediated post-transcriptional regulation. We sought to define the underlying mechanism. VASH1 increased the expression of (superoxide dismutase 2) SOD2, an enzyme known to quench reactive oxygen species (ROS). Simultaneously, VASH1 augmented the synthesis of sirtuin 1 (SIRT1), an anti-aging protein, which improved stress tolerance. Paraquat generates ROS and causes organ damage when administered in vivo. More VASH1 (+/-) mice died due to acute lung injury caused by paraquat. Intratracheal administration of an adenovirus vector encoding human VASH1 augmented SOD2 and SIRT1 expression in the lungs and prevented acute lung injury caused by paraquat. Thus, VASH1 is a critical factor that improves the stress tolerance of ECs via the induction of SOD2 and SIRT1.

Reduced expression of vasohibin-1 is associated with clinicopathological features in renal cell carcinoma

Vasohibin-1(VASH1) has recently been isolated as a novel negative feedback inhibitor of angiogenesis. Several studies have demonstrated that VASH1 plays important roles in tumor angiogenesis but the role of this angiogenic inhibitor in renal cell carcinoma (RCC) has not been elucidated until now. In this study, we investigated the expression pattern of VASH1 and the association with clinicopathological features in RCC. Expression of VASH1, hypoxia-inducible factor-1α (HIF-1α), and microvessel density (MVD, labeled by CD34) was assessed by immunohistochemistry in 46 RCC specimens and 20 adjacent nontumorous renal tissues (ANRTs). Correlation between vasohibin-1 and HIF-1α, MVD, and clinicopathological features was then investigated. In RCC, VASH1 was expressed mainly in the cytoplasm and membrane of tumor cells and partly in vascular endothelial cells. In ANRT, it was mainly expressed in the cytoplasm and membrane of renal tubular epithelial cells and partly in vascular endothelial cells and glomerular mesangial cells. The expression level of VASH1 in RCC tissue was significantly lower than that in ANRT and was significantly reduced with the increased degree of malignancy in RCC tissues. In addition, a significantly negative correlation was noted between VASH1 expression and HIF-1α expression and a significantly negative correlation was noted between VASH1 expression and MVD in RCC. Therefore, VASH1 expression is reduced and it associates with clinicopathological features in RCC. Based on our findings and the knowledge of other angiogenesis inhibitors, we postulate that VASH1 would potentially be a biomarker and a candidate for molecular targeted therapy for patients with RCC in the future.

Reduction of laser-induced choroidal neovascularization by intravitreal vasohibin-1 in monkey eyes

PURPOSE

To determine whether intravitreal vasohibin-1 will reduce the grade of the choroidal neovascularization in monkey eyes.

METHODS

Choroidal neovascularizations were induced in 12 monkey eyes by laser photocoagulation. Three monkeys were evaluated for the safety of the vasohibin-1 injections, 6 monkeys for the effects of a single injection, and 3 monkeys for repeated injections of vasohibin-1. Ophthalmoscopy, fluorescein angiography, focal electroretinograms, and optical coherence tomography were used for the evaluations. The level of vascular endothelial growth factor in the aqueous was determined by enzyme-linked immunosorbent assay. Immunohistochemistry was performed.

RESULTS

An intravitreal injection of 10 μg of vasohibin-1 induced mild intraocular inflammation. Eyes with an intravitreal injection of 0.1 μg and 1.0 μg of vasohibin-1 had significant less fluorescein leakage from the choroidal neovascularizations and larger amplitude focal electroretinograms than that of vehicle-injected eyes. Similar results were obtained by repeated injections of 0.1 μg of vasohibin-1. Immunohistochemistry showed that vasohibin-1 was expressed mainly in the endothelial cells within the choroidal neovascularizations. The vascular endothelial growth factor level was not significantly altered by intravitreal vasohibin-1.

CONCLUSION

The reduction of the laser-induced choroidal neovascularizations and preservation of macular function in monkey by intravitreal vasohibin-1 suggest that it should be considered for suppressing choroidal neovascularizations in humans.

Possible action of vasohibin-1 as an inhibitor in the regulation of vascularization of the bovine corpus luteum

The development of the corpus luteum (CL), which secretes large amounts of progesterone to establish pregnancy, is accompanied by active angiogenesis, vascularization, and lymphangiogenesis. Negative feedback regulation is a critical physiological mechanism. Vasohibin-1 (VASH1) was recently discovered as a novel endothelium-derived negative feedback regulator of vascularization. We therefore investigated the expression of VASH1 in the bovine CL. Expression of VASH1 mRNA and protein was predominantly localized to luteal endothelial cells (LECs). VASH1 expression in the CL was constant through the early to late luteal phases and decreased during CL regression relating with the action of luteolytic prostaglandin F2α in vivo. To investigate the role of VASH1, we determined whether VASH1 treatment affects angiogenesis and/or lymphangiogenesis using LECs and lymphatic endothelial cells (LyECs) in vitro. Vascular endothelial growth factor A (VEGFA) stimulated the expression of VASH1 in LECs but not in LyECs, and VASH1 completely blocked VEGFA-induced formation of capillary-like tube structures of LECs and LyECs in vitro. In summary, VASH1 is predominantly located on LECs in the bovine CL and inhibits the angiogenic and lymphangiogenic actions of VEGFA. Bovine CL therefore has a VEGFA–VASH1 system that may be involved in regulation of luteal function, especially in the development of the CL. The results indicate that VASH1 has the potential to act as a negative feedback regulator of angiogenesis and lymphangiogenesis in the CL in cows.

The vasohibin family: Novel regulators of angiogenesis

Angiogenesis is thought to be regulated by the local balance between angiogenesis stimulators and angiogenesis inhibitors. A number of endogenous regulators of angiogenesis have been found in the body. We recently isolated vasohibin-1 (VASH1) as a negative feedback regulator of angiogenesis produced by endothelial cells, and VASH2 as a homologue of VASH1 thereafter. We found that VASH1 was expressed in endothelial cells to terminate angiogenesis, whereas VASH2 promoted angiogenesis, in the mouse model of angiogenesis. This mini-review will focus on the vasohibin family in relation to the regulation of angiogenesis.

Proteolytically Derived Endogenous Angioinhibitors Originating from the Extracellular Matrix

Angiogenesis, a neovascularization process induced from the existing parent blood vessels, is a prerequisite for many physiological and pathological conditions. Under physiological conditions it is regulated by a balance between endogenous angioinhibitors and angioactivators, and an imbalance between them would lead to pathological conditions such as cancer, age-related macular degeneration (AMD), diabetic retinopathy, cardiovascular diseases, etc. Several proteolytically generated endogenous molecules have been identified which exhibit angioinhibition and/or antitumor activities. These angioinhibitors interact with endothelial and tumor cells by binding to distinct integrins and initiate many of their intracellular signaling mechanisms regulating the cell survival and or apoptotic pathways. The present review will focus on the extracellular matrix derived angioinhibitors, and their mechanisms of actions that point to the clinical significance and therapeutic implications.

Gene transfer for ocular neovascularization and macular edema

Diseases complicated by abnormal growth of vessels or excessive leakage are the most prevalent cause of moderate or severe vision loss in developed countries. Recent progress unraveling the molecular pathogenesis of several of these disease processes has led to new drug therapies that have provided major benefits to patients. However, those treatments often require frequent intraocular injections, and despite monthly injections, some patients have a suboptimal response. Gene transfer of antiangiogenic proteins is an alternative approach that has the potential to provide long-term suppression of neovascularization (NV) and/or excessive vascular leakage in the eye. Studies in animal models of ocular NV have demonstrated impressive results with a number of transgenes, and a clinical trial in patients with advanced neovascular age-related macular degeneration has provided proof-of-concept. Two ongoing clinical trials, one using an adeno-associated viral (AAV) vector to express a vascular endothelial growth factor-binding protein and another using a lentiviral vector to express endostatin and angiostatin, will provide valuable information that should help to inform future trials and provide a foundation on which to build.

Mutual Balance between Vasohibin-1 and Soluble VEGFR-1 in Endothelial Cells

Vasohibin-1 (VASH1) is a VEGF-inducible gene of endothelial cells (ECs) that acts as a negative feedback regulator of angiogenesis. To further characterize the function of VASH1, we transfected human VASH1 gene into the mouse EC line MS1, established stable VASH1 expressing clones, and determined gene alteration by cDNA microarray analysis. Among the various angiogenesis-related genes, vascular endothelial growth factor type 1 receptor (VEGFR-1) and its alternative spliced form, soluble VEGFR1 (sVEGFR-1), were found to be the most significantly down-regulated genes. Transient overexpression of VASH1 in human umbilical vein endothelial cells confirmed the down-regulation of VEGFR-1 and sVEGFR-1. sVEGFR-1 is a decoy receptor for VEGF and inhibits angiogenesis. Interestingly, when sVEGFR-1 was overexpressed in ECs, it inhibited the expression of VASH1 in turn. These results suggest that VASH1 and sVEGFR-1, two angiogenesis inhibitors, mutually balance their expressions in ECs.

Roles of intrinsic angiogenesis inhibitor, vasohibin, in cervical carcinomas

The aim of the present study is to clarify the critical roles of vasohibin in cervical carcinomas. We investigated the expression ratios of vasohibin and vascular endothelial growth factor (VEGF) receptor-2 on endothelium and microvessel density, lymphatic vessel density (LVD) by immunohistochemistry. Sixty-one squamous cell carcinoma (SCC), 18 mucinous adenocarcinoma (Adenocarcinoma), 38 carcinoma in situ (CIS), and 35 normal cervical epithelium were collected. We investigated the expression of vasohibin and compared it with the expression of VEGF receptor-2 (VEGFR-2, KDR/flk-1), and CD34 in the stromal endothelium. Expression of VEGF was counted using the histological score (H score). D2-40 was used as a marker for lymphatic endothelial cells to investigate LVD. The microvessel density of the normal cervical epithelium was significantly lower than that of CIS, SCC, and Adenocarcinoma (P < 0.05). The expression ratio of vasohibin in the normal cervical epithelium was significantly lower than that of SCC and Adenocarcinoma (P < 0.05). The expression ratio of VEGFR-2 of the normal cervical epithelium was significantly lower than that of SCC and Adenocarcinoma (P < 0.05). The LVD of the normal cervical epithelium was significantly lower than that of CIS, SCC, and Adenocarcinoma (P < 0.05). For normal cervical epithelium, CIS, and SCC, there was a moderate correlation between the expression percentage of vasohibin and the expression percentage of VEGFR-2 (P < 0.05, r(2) = 0.3018). This is the first study to elucidate the correlation between the expression of vasohibin in the stromal endothelial cells and the expression of VEGFR-2 in human cervical carcinomas.

Protein kinase C{delta} deficiency accelerates neointimal lesions of mouse injured artery involving delayed reendothelialization and vasohibin-1 accumulation

OBJECTIVE

To use protein kinase C (PKC) δ-knockout mice to investigate the role of PKCδ in lesion development and to understand the underlying mechanism of the vascular disease.

METHODS AND RESULTS

PKCδ functions as a signal transducer mediating several essential functions of cell proliferation and apoptosis. However, the effect of PKCδ on neointimal formation in wire-injured vessels is unknown. Three weeks after wire injury of femoral arteries, neointimal lesions were significantly increased in PKCδ(-/-) mice compared with PKCδ(+/+) animals. Immunohistochemical staining revealed that total numbers of smooth muscle cells and macrophages in the lesions of PKCδ(-/-) mice were markedly elevated without changing the ratio of these 2 cell types. To further elucidate the mechanisms of PKCδ-mediated increase in the lesion, an in vivo endothelial migration model was established to evaluate endothelial wound healing after wire injury. Data showed that reendothelialization of the injured vessel was markedly delayed in PKCδ(-/-) mice; this coincided with more severe intimal hyperplasia. Migration of endothelial cells cultivated from cardiac tissue was markedly reduced in the absence of PKCδ, whereas no difference in proliferation or apoptosis was detected. Inhibition of PKCδ activity or protein expression by small hairpin RNA (shRNA) in cultured endothelial cells confirmed the defective migratory phenotype. Interestingly, vasohibin-1, an antiangiogenesis protein, was elevated in endothelial cells derived from PKCδ(-/-) mice, which was mainly because of delayed protein degradation mediated by PKCδ. Downregulation of vasohibin-1 restored the migration rate of PKCδ(-/-) endothelial cells to a similar level as PKCδ(+/+) cells.

CONCLUSIONS

PKCδ deficiency enhances neointimal formation, which is associated with delayed reendothelialization and involves increased cellular vasohibin-1 accumulation.

Isolation of a small vasohibin-binding protein (SVBP) and its role in vasohibin secretion

Upon stimulation with angiogenic factors, vascular endothelial cells (ECs) secrete a negative-feedback regulator of angiogenesis, vasohibin-1 (VASH1). Because VASH1 lacks a classical signal sequence, it is not clear how ECs secrete VASH1. We isolated a small vasohibin-binding protein (SVBP) composed of 66 amino acids. The level of Svbp mRNA was relatively high in the bone marrow, spleen and testes of mice. In cultured ECs, Vash1 mRNA was induced by VEGF, and Svbp mRNA was expressed constitutively. The interaction between VASH1 and SVBP was confirmed using the BIAcore system and immunoprecipitation analysis. Immunocytochemical analysis revealed that SVBP colocalized with VASH1 in ECs. In polarized epithelial cells, SVBP accumulated on the apical side, whereas VASH1 was present throughout the cells and partially colocalized with SVBP. Transfection of SVBP enhanced VASH1 secretion, whereas knockdown of endogenous SVBP markedly reduced VASH1 secretion. SVBP increased the solubility of VASH1 protein in detergent solution and inhibited the ubiquitylation of VASH1 protein. Moreover, co-transfection of SVBP significantly augmented the inhibitory effect of VASH1 on EC migration. These results indicate that SVBP acts as a secretory chaperone for VASH1 and contributes to the anti-angiogenic activity of VASH1.

Prostaglandin F2alpha differentially affects mRNA expression relating to angiogenesis, vasoactivation and prostaglandins in the early and mid corpus luteum in the cow

Administration of prostaglandin (PG) F(2alpha) in cattle during the mid-luteal phase (Days 8-12 of the estrous cycle) drastically reduces the plasma progesterone concentrations and the volume of the corpus luteum (CL). However, PGF(2alpha) does not induce luteolysis during the early luteal phase (up to Day 5 of the estrous cycle). To characterize the possible distinct difference in acute response to a luteolytic dose of PGF(2alpha) administration, we determined various mRNA expressions in the early and mid CL relating to angiogenesis, vasoactivation and PG-related factors at 30 min after PGF(2alpha) injection in cyclic cows. The experiments were conducted on Day 4 (early CL) and Days 10-12 (mid CL). Cows were either injected with 500 microg PGF(2alpha) analogue or saline as the control (early CL control, n=5; early CL PGF(2alpha) treated, n=5; mid CL control, n=5; mid CL PGF(2alpha) treated, n=7). Thirty min after injection of PGF(2alpha) or saline, the cows were ovariectomized transvaginally, and the CL tissues were collected from regions designated as the periphery and center of the CL. Administration of PGF(2alpha) up-regulated the mRNA expressions of angiogenic-related factors such as vascular endothelial growth factors, vasohibin, fibroblast growth factor 2 and insulin-like growth factor-II in the early CL, whereas PGF(2alpha) down-regulated these mRNA expressions in the mid CL. In the vasoactive factors, PGF(2alpha) stimulated the mRNA expressions of endothelin-1, angiotensin converting enzyme, endothelial nitric oxide synthase (NOS) and inducible NOS in the periphery area of the mid CL, but not in the early CL. However, PGF(2alpha) drastically down-regulated PGF(2alpha) receptor mRNA expression in both regions of the early and mid CL. The results indicated a clear difference in the acute action of PGF(2alpha) depending not only on the luteal phase (immature vs. mature) but also the region (periphery vs. center) within the CL at 30 min after PGF(2alpha) injection in the cow.