Inhibition of angiogenesis and breast cancer xenograft tumor growth by VEGI, a novel cytokine of the TNF superfamily

The Relation of VEGFA, VEGFR2, VEGI, and HIF1A Genetic Variants and Their Serum Protein Levels with Breast Cancer in Egyptian Patients

Breast cancer is the most common type of cancer in Egyptian females. Polymorphisms in the angiogenesis pathway have been implicated previously in cancer risk and prognosis. The aim of the current study was to determine whether certain polymorphisms in the genes of vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor receptor 2 (VEGFR2), vascular endothelial growth inhibitor (VEGI), and hypoxia-inducible factor-1α (HIF1A) associated with breast cancer development. The study included 154 breast cancer patients and 132 apparently healthy age-matched females as a control group. VEGFA rs25648 genotyping was performed using (ARMS) PCR technique; while VEGFR2 rs2071559, VEGI rs6478106, and HIF-1α rs11549465 were genotyped by the PCR-RFLP method. Serum levels of VEGF, VEGFR2, VEGI, and HIF1A proteins in breast cancer patients and controls were measured by ELISA. There was a significant association between the VEGFA rs25648 C allele and breast cancer risk (OR 2.5, 95% CI 1.7-3.6, p < 0.001). VEGFA rs25648 C/C genotype was statistically significantly higher in breast cancer patients vs. control (p < 0.001). Participants with the T/T and T/C VEGFR2 rs2071559 genotypes had 5.46 and 5 higher odds, respectively, of having breast cancer than those with the C/C genotype. For the VEGI rs6478106 polymorphism, there was a higher proportion of C allele in breast cancer patients vs. control (p = 0.003). Moreover, the C/C genotype of VEGI rs6478106 was statistically significantly higher in breast cancer patients vs. control (p = 0.001). There was no significant difference in genotypes and allele frequencies of HIF1A rs11549465 polymorphism between breast cancer cases and control individuals (p > 0.05). Serum levels of VEGFA, VEGI, and HIF1A were considerably greater in women with breast cancer than in the control (p < 0.001). In conclusion, the genetic variants VEGFA rs25648, VEGFR2 rs2071559, and VEGI rs6478106 revealed a significant association with increased breast cancer risk in Egyptian patients.

Bradykinin-pretreated Human cardiac-specific c-kit+ Cells Enhance Exosomal miR-3059-5p and Promote Angiogenesis Against Hindlimb Ischemia in mice

BACKGROUND

Protection of cardiac function following myocardial infarction was largely enhanced by bradykinin-pretreated cardiac-specific c-kit+ (BK-c-kit+) cells, even without significant engraftment, indicating that paracrine actions of BK-c-kit+ cells play a pivotal role in angiogenesis. Nevertheless, the active components of the paracrine actions of BK-c-kit+ cells and the underlying mechanisms remain unknown. This study aimed to define the active components of exosomes from BK-c-kit+ cells and elucidate their underlying protective mechanisms.

METHODS

Matrigel tube formation assay, cell cycle, and mobility in human umbilical vein endothelial cells (HUVECs) and hindlimb ischemia (HLI) in mice were applied to determine the angiogenic effect of condition medium (CM) and exosomes. Proteome profiler, microRNA sponge, Due-luciferase assay, microRNA-sequencing, qRT-PCR, and Western blot were used to determine the underlying mechanism of the angiogenic effect of exosomes from BK-c-kit+.

RESULTS

As a result, BK-c-kit+ CM and exosomes promoted tube formation in HUVECs and the repair of HLI in mice. Angiogenesis-related proteomic profiling and microRNA sequencing revealed highly enriched miR-3059-5p as a key angiogenic component of BK-c-kit+ exosomes. Meanwhile, loss- and gain-of-function experiments revealed that the promotion of angiogenesis by miR-3059-5p was mainly through suppression of TNFSF15-inhibited effects on vascular tube formation, cell proliferation and cell migration. Moreover, enhanced angiogenesis of miR-3059-5p-inhibited TNFSF15 has been associated with Akt/Erk1/2/Smad2/3-modulated signaling pathway.

CONCLUSION

Our results demonstrated a novel finding that BK-c-kit+ cells enrich exosomal miR-3059-5p to suppress TNFSF15 and promote angiogenesis against hindlimb ischemia in mice.

Dual-targeted and dual-sensitive self-assembled protein nanocarrier delivering hVEGI-192 for triple-negative breast cancer

Breast cancer is a highly prevalent malignancy worldwide among women with an increasing incidence in recent years. Triple-negative breast cancer (TNBC), a specific type of breast cancer, occurs primarily in young women and exhibits large tumor size, high clinical stage, and extremely poor prognosis with a high rate of lymph node, liver, and lung metastases. TNBC is insensitive to endocrine therapy and trastuzumab treatment, and there is an urgent need for effective therapeutics and treatment guidelines. However, investigations into antiangiogenic agents for the treatment of TNBC are ongoing. In this study, we successfully engineered a self-assembled protein nanocarrier TfRBP9-hVEGI-192-ELP fusion protein (TVEFP) to deliver the therapeutic protein, human vascular endothelial growth inhibitor (hVEGI-192). This was found to be effective in inhibiting tumor angiogenesis in vivo. The protein nanocarrier effectively inhibited the progression of TNBC in vivo and showed the behavior of self-assembly, thermoresponsiveness, enzyme stimulation-responsiveness, tumor-targeting, biocompatibility, and biodegradability. Near-infrared imaging studies showed that fluorescent dye-stained TVEFP effectively aggregated at the tumor site. The TVEFP nanocarrier significantly expands the application of the therapeutic protein hVEGI-192 and improves the imaging and biotherapeutic effects in TNBC, chiefly based on anti-angiogenesis effects.

PCDHB17P/miR-145-3p/MELK/NF-κB Feedback Loop Promotes Metastasis and Angiogenesis of Breast Cancer

Breast cancer is one of the most common life-threatening cancers, mainly because of its aggressiveness and metastasis. Accumulating evidence indicates that long non-coding RNAs (lncRNAs) participate in the development and progression of breast cancer. Nevertheless, the function and expression level of lncRNAs in breast cancer are still not fully understood. Here, we demonstrated that lncRNA PCDHB17P was up-expressed in human breast cancer tissues and cell lines. Knockdown of PCDHB17P remarkably suppressed migration and invasion, as well as tube formation ability of breast cancer cells. MiR-145-3p was significantly decreased in breast cancer samples, which was negatively correlated to the expression of PCDHB17P. In addition, we identified that MELK was a direct target gene of miR-145-3p, which was higher expressed in breast cancer tissues than that in adjacent normal tissues. Mechanistic investigation indicated that PCDHB17P acted as a cancer-promoting competing endogenous RNA (ceRNA) by binding miR-145-3p and upregulating MELK. Interestingly, MELK could in turn increase the promoter activity and expression of PCDHB17P via NF-κB, thus forming a positive feedback loop that drives the metastasis and angiogenesis of breast cancer. Overall, the results demonstrated that the constitutive activation of PCDHB17P/miR-145-3p/MELK/NF-κB feedback loop promotes the metastasis and angiogenesis of breast cancer, suggesting that this lncRNA might be a promising prognostic biomarker and therapeutic target for breast cancer.

Signaling in TNFSF15-mediated Suppression of VEGF Production in Endothelial Cells

Vascular endothelial growth factor (VEGF) plays a pivotal role in promoting neovascularization. Tumor necrosis factor superfamily 15 (TNFSF15) is an antiangiogenic cytokine prominently produced by endothelial cells in a normal vasculature. In this study, Western blot, quantitative polymerase chain reaction (qPCR), and dual luciferase reporter gene assay were used to validate the mechanisms of TNFSF15-mediated suppression of VEGF production in endothelial cells. We report that TNFSF15 inhibits VEGF production via microRNA-29b (miR-29b) targeting the 3'-UTR of VEGF transcript in mouse endothelial cell line bEnd.3. Neutralizing antibody against TNFSF15, 4-3H, inhibits the level of miR-29b and reinvigorates VEGF. In addition, TNFSF15 activates the JNK signaling pathway as well as the transcription factor GATA3, resulting in enhanced miR-29b production. SP600125, an inhibitor of JNK, eradicates TNFSF15-induced GATA3 expression. Moreover, GATA3 siRNA suppressed TNFSF15-induced miR-29b expression. Together, this study provides evidence and method of activation of the JNK-GATA3 signaling pathway by TNFSF15 that suppresses VEGF gene expression, which gives rise to upregulation of miR-29b.

Tumour-associated macrophages as a novel target of VEGI-251 in cancer therapy

Tumour‐associated macrophages (TAMs), which possess M2‐like characters and are derived from immature monocytes in the circulatory system, represent a predominant population of inflammatory cells in solid tumours. TAM infiltration in tumour microenvironment can be used as an important prognostic marker in many cancer types and is a potential target for cancer prevention or treatment. VEGI‐251 not only is involved in the inhibition of tumour angiogenesis, but also participates in the regulation of host immunity. This work aimed to investigate the involvement of VEGI‐251 in the regulation of specific antitumour immunity. We found that recombinant human VEGI‐251(rhVEGI‐251) efficiently mediated the elimination of TAMs in tumour tissue in mice, and induced apoptosis of purified TAMs in vitro. During this process, caspase‐8 and caspase‐3 were activated, leading to PARP cleavage and apoptosis. Most importantly, we further elucidated the mechanism underlying VEGI‐251‐triggered TAM apoptosis, which suggests that ASK1, an intermediate component of the VEGI‐251, activates the JNK pathway via TRAF2 in a potentially DR3‐dependent manner in the process of TAM apoptosis. Collectively, our findings provide new insights into the basic mechanisms underlying the actions of VEGI‐251 that might lead to future development of antitumour therapeutic strategies using VEGI‐251 to target TAMs.

Long non-coding RNA NKILA inhibited angiogenesis of breast cancer through NF-κB/IL-6 signaling pathway

OBJECTIVE

The relationship between NF-κB Interacting lncRNA (NKILA) and angiogenesis in breast cancer has never been studied. Our study aimed to investigate effect of NKILA on proliferation, migration, apoptosis, as well as angiogenesis in breast cancer.

METHODS

NKILA was over-expressed in MDA-MB-231 cells by transfection of pcDNA3.1-NKILA vector. Cell viability, apoptosis and migration were measured by MTT, flow cytometry and wound healing assays, respectively. Angiogenesis of human umbilical vein endothelial cells (HUVEC) was measured using tube formation assay. The expression levels of NKILA, IL-6, VEGFA, VEGFR, apoptosis and epithelial-mesenchymal transition (EMT) and NF-κB/IL-6 signaling-related markers were determined using qRT-PCR or Western blotting.

RESULTS

Cell viability and migration of MDA-MB-231 cells were significantly inhibited, while cell apoptosis was obviously promoted by overexpression of NKILA. Overexpression of NKILA could also inhibit the phosphorylation of IκBα and the nuclear transposition of p65, as well as induce cell apoptosis-related proteins and inhibit epithelial-mesenchymal transition-related proteins. Cell viability and migration of HUVEC were also significantly inhibited when treated with supernatant of cells overexpressed NKILA or treated with BAY11-7028. Exogenous IL-6 significantly increased the cell viability and migration of HUVEC, and overexpression of NKILA could reverse these effects induced by IL-6. Overexpression of NKILA significantly inhibited the protein levels of IL-6 and VEGFA in supernatant, as well as VEGFR in HUVEC, thus inhibited the angiogenesis of HUVEC. NKILA also reversed the above effects on protein levels of IL-6 and VEGFA in supernatant and angiogenesis induced by exogenous IL-6.

CONCLUSION

Overexpression of NKILA could inhibit cell proliferation, migration and promote apoptosis of breast cancer cells. It could also inhibit cell proliferation, migration and angiogenesis of HUVEC through inhibiting IL-6 secretion via NF-κB signaling pathway.

TNF-like ligand 1A is associated with progression and prognosis of human gastric cancer

Purpose

This study aimed to investigate the function of TNF-like ligand 1A (TL1A) in the tumorigenesis and progression of gastric cancer (GC).

Methods

RNA-seq gene expression and clinical information for GC patients were obtained from The Cancer Genome Atlas (TCGA) database. Differentially expressed genes (DEGs) between GC tissue samples and normal controls were screened with the edgeR package. Identification of gene co-expression and functional enrichment analyses were performed with Pearson’s correlation analysis and gene set enrichment analysis (GSEA), respectively. Lastly, survival analysis was performed using the Kaplan-Meier method with the log rank test.

Results

TL1A expression in GC tissue samples were significantly higher than that in normal controls (LogFC=1.07 and P=8.90E-07). Moreover, 215 genes, co-expressed with TL1A, and 21 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were obtained. Next, the miRNA-lncRNA/mRNA network, comprising 7 miRNAs, 27 lncRNAs, and 21 mRNAs, was constructed based on key genes from intersections between co-expression analysis and GSEA. In addition, survival analysis results demonstrated that TL1A (P=2.6e−07) was significantly associated with the overall survival (OS) of GC patients.

Conclusion

TL1A was involved in the tumorigenesis and progression of GC, and was significantly associated with the OS of GC patients.

Vascular Endothelial Growth Inhibitor, a Cytokine of the Tumor Necrosis Factor Family, is Associated With Epithelial-Mesenchymal Transition in Renal Cell Carcinoma

Previous studies have revealed that the activation of the epithelial-mesenchymal transition (EMT) endows metastatic properties upon cancer cells to promote invasion and migration. In this study, immunohistochemical analysis was performed in 50 cases of clear cell renal cell carcinoma (RCC) and paired normal kidney tissues. We detected the expression of vascular endothelial growth inhibitor (VEGI) and EMT markers (E-cadherin, fibronectin, and Slug) and recorded the clinical, pathologic, and follow-up (median follow-up: 79.0 mo) information. The expression of VEGI and E-cadherin was significantly lower in RCC tissues compared with normal kidney tissues (P<0.001). However, the expression of fibronectin and Slug was higher in RCC tissues (P<0.05). VEGI and EMT marker expression marginally differed in tumor size and stage. Significant differences were found in the pathologic grade (P<0.05). The Spearman correlation analysis suggested a positive correlation between VEGI and E-cadherin (r=0.451, P<0.01). A negative correlation was shown between VEGI and fibronectin (r=-0.465, P<0.01). There was also a negative correlation between VEGI and Slug (r=-0.758, P<0.01). During the 79.0 months (range, 7 to 119 mo) of follow-up, 6 patients died due to RCC, and the tumor-free survival rate was 88% (44/50). We did not find a significant correlation between VEGI/EMT markers (E-cadherin, fibronectin, and Slug) and overall survival (P>0.05). Our findings indicate that VEGI plays an important role in EMT in RCC. It suggests that VEGI may be investigated as a disease biomarker and therapeutic target in RCC.

VEGI174 protein and its functional domain peptides exert antitumour effects on renal cell carcinoma

Vascular endothelial growth inhibitor (VEGI) has been identified as an anti‑angiogenic cytokine. However, the effects of VEGI174 protein, and its functional domain peptides V7 and V8, on renal cell carcinoma (RCC) remain unknown. In the present study, the protein and peptides were biosynthesised as experimental agents. The A498 and 786‑O RCC cell lines, and an established mouse xenograft model, were separately treated with VEGI174, V7 or V8. Cellular functions, including proliferation, migration and invasion, were subsequently detected. Cell migration and invasion were monitored using the xCELLigence system. Furthermore, tumour growth and mouse behaviours, including mobility, appetite and body weight, were assessed. The results demonstrated that VEGI174, V7 and V8 inhibited the proliferation, migration and invasion of A498 and 786‑O cell lines when administered at concentrations of 1 and 100 pM, 10 nM and 1 µM. The inhibitory effects exhibited dose‑ and time‑dependent antitumour activity. Furthermore, VEGI174, V7 and V8 inhibited tumour growth in A498 and 786‑O xenograft mice. In the A498 xenografts, the tumour growth inhibition (TGI) rates in the VEGI174‑, V7‑ and V8‑treated groups were 71, 20 and 31%, respectively. In the 786‑O xenografts, the TGI rates in the VEGI174‑, V7‑ and V8‑treated groups were 34, 26 and 31%, respectively. There was no significant loss in body weight and no cases of mortality were observed for all treated mice. In conclusion, VEGI174, V7 and V8 exhibited potential antitumour effects and were well tolerated in vivo. V7 and V8, as functional domain peptides of the VEGI174 protein, may be studied for the future treatment of RCC.

Counterbalance: modulation of VEGF/VEGFR activities by TNFSF15

Vascular hyperpermeability occurs in angiogenesis and several pathobiological conditions, producing elevated interstitial fluid pressure and lymphangiogenesis. How these closely related events are modulated is a fundamentally important question regarding the maintenance of vascular homeostasis and treatment of disease conditions such as cancer, stroke, and myocardial infarction. Signals mediated by vascular endothelial growth factor receptors, noticeably VEGFR-1, −2, and −3, are centrally involved in the promotion of both blood vessel and lymphatic vessel growth. These signaling pathways are counterbalanced or, in the case of VEGFR3, augmented by signals induced by tumor necrosis factor superfamily-15 (TNFSF15). TNFSF15 can simultaneously downregulate membrane-bound VEGFR1 and upregulate soluble VEGFR1, thus changing VEGF/VEGFR1 signals from pro-angiogenic to anti-angiogenic. In addition, TNFSF15 inhibits VEGF-induced VEGFR2 phosphorylation, thereby curbing VEGFR2-mediated enhancement of vascular permeability. Third, and perhaps more interestingly, TNFSF15 is capable of stimulating VEGFR3 gene expression in lymphatic endothelial cells, thus augmenting VEGF-C/D-VEGFR3-facilitated lymphangiogenesis. We discuss the intertwining relationship between the actions of TNFSF15 and VEGF in this review.

The ability of tumor necrosis factor superfamily-15 (TNFSF15) protein to balance the actions of vascular endothelial growth factors (VEGFs) highlights new therapeutic strategies for the treatment of diseases that disrupt the circulatory system. Gui-Li Yang at the Tianjin Neurological Institute and Lu-Yuan Li at Nankai University describe the mechanisms through which TNFSF15 inhibits blood vessel growth mediated by VEGF receptor-1 (VEGFR1) and counterbalances the increase in vascular permeability mediated by VEGFR2. Interestingly, TNFSF15 enhances the effects of VEGFR3 on the formation of lymphatic vessels by promoting VEGFR3 gene expression in lymphatic endothelial cells. Further research will determine whether TNFSF15′s unique capacity to regulate the properties of both blood and lymph vessels can be harnessed to improve the treatment of conditions such as cancer, stroke, myocardial infarction and lymphoedema.

TNFSF15 suppresses VEGF production in endothelial cells by stimulating miR-29b expression via activation of JNK-GATA3 signals

Vascular endothelial cell growth factor (VEGF) plays a pivotal role in promoting neovascularization. VEGF gene expression in vascular endothelial cells in normal tissues is maintained at low levels but becomes highly up-regulated in a variety of disease settings including cancers. Tumor necrosis factor superfamily 15 (TNFSF15; VEGI; TL1A) is an anti-angiogenic cytokine prominently produced by endothelial cells in a normal vasculature. We report here that VEGF production in mouse endothelial cell line bEnd.3 can be inhibited by TNFSF15 via microRNA-29b (miR-29b) that targets the 3'-UTR of VEGF transcript. Blocking TNFSF15 activity by using either siRNA against the TNFSF15 receptor known as death domain-containing receptor-3 (DR3; TNFRSF25), or a neutralizing antibody 4-3H against TNFSF15, led to inhibition of miR-29b expression and reinvigoration of VEGF production. In addition, we found that TNFSF15 activated the JNK signaling pathway as well as the transcription factor GATA3, resulting in enhanced miR-29b production. Treatment of the cells either with SP600125, an inhibitor of JNK, or with JNK siRNA, led to eradication of TNFSF15-induced GATA3 expression. Moreover, GATA3 siRNA suppressed TNFSF15-induced miR-29b expression. These findings suggest that VEGF gene expression can be suppressed by TNFSF15-stimulated activation of the JNK-GATA3 signaling pathway which gives rise to up-regulation of miR-29b.

Vascular endothelial growth inhibitor 174 and its functional domains inhibit epithelial-mesenchymal transition in renal cell carcinoma cells in vitro

The present study was carried out to investigate the effects of vascular endothelial growth inhibitor 174 (VEGI174) and its functional domains (V7 and V8) on epithelial‑mesenchymal transition (EMT) in renal cell carcinoma (RCC) cells in vitro. The RCC cell lines A498 and 786‑O were used in this study. Based on our preliminary study, we selected full‑length VEGI174 and its functional domains (V7 and V8) as the target genes in this study. Plasmids containing VEGI174, V7 or V8 transgenes were constructed and transfected into A498 and 786‑O cell lines. Cytological activity was tested during cell culture. Quantitative PCR and western blot analysis were performed to determine the expression levels of EMT markers (E‑cadherin, vimentin, β‑catenin and Slug). Overexpression of VEGI174, V7 or V8 did not have a significant influence on cell viability (P>0.05). The mRNA level of E‑cadherin was significantly upregulated, while that of vimentin was downregulated in A498VEGIexp, A498V7exp, A498V8exp, 786‑OVEGIexp, 786‑OV7exp and 786‑OV8exp cells compared with the cells containing the empty plasmid controls (P<0.05). The western blot results showed that changes in protein expression levels were consistent with the changes in mRNA expression. Both the mRNA and protein expression levels of β‑catenin and Slug were downregulated in the A498VEGIexp, A498V7exp, A498V8exp, 786‑OVEGIexp, 786‑OV7exp and 786‑OV8exp cells. In conclusion, overexpression of VEGI174, V7 or V8 inhibited EMT in A498 and 786‑O cells. Notably, V7 and V8 are two effective functional domains of VEGI174 that have the potential to be studied for peptide synthesis and the treatment of RCC.

TNFSF15 inhibits VEGF-stimulated vascular hyperpermeability by inducing VEGFR2 dephosphorylation

Vascular hyperpermeability is critical in ischemic diseases, including stroke and myocardial infarction, as well as in inflammation and cancer. It is well known that the VEGF-VEGFR2 signaling pathways are pivotal in promoting vascular permeability; however, counterbalancing mechanisms that restrict vascular permeability to maintain the integrity of blood vessels are not yet fully understood. We report that TNF superfamily member 15 (TNFSF15), a cytokine largely produced by vascular endothelial cells and a specific inhibitor of the proliferation of these same cells, can inhibit VEGF-induced vascular permeability in vitro and in vivo, and that death receptor 3 (DR3), a cell surface receptor of TNFSF15, mediates TNFSF15-induced dephosphorylation of VEGFR2. Src homology region 2 domain-containing phosphatase-1 (SHP-1) becomes associated with DR3 upon TNFSF15 interaction with the latter. In addition, a protein complex consisting of VEGFR2, DR3, and SHP-1 is formed in response to the effects of TNFSF15 and VEGF on endothelial cells. It is plausible that this protein complex provides a structural basis for the molecular mechanism in which TNFSF15 induces the inhibition of VEGF-stimulated vascular hyperpermeability.-Yang, G.-L., Zhao, Z., Qin, T.-T., Wang, D., Chen, L., Xiang, R., Xi, Z., Jiang, R., Zhang, Z.-S., Zhang, J., Li. L.-Y. TNFSF15 inhibits VEGF-stimulated vascular hyperpermeability by inducing VEGFR2 dephosphorylation.

Vascular endothelial growth factor suppresses TNFSF15 production in endothelial cells by stimulating miR-31 and miR-20a expression via activation of Akt and Erk signals

Tumor necrosis factor superfamily‐15 (TNFSF15; VEGI; TL1A) is a negative modulator of angiogenesis for blood vessel homeostasis and is produced by endothelial cells in a mature vasculature. It is known to be downregulated by vascular endothelial growth factor (VEGF), a major regulator of neovascularization but the mechanism of this interaction is unclear. Here we report that VEGF is able to stimulate the production of two microRNAs, miR‐20a and miR‐31, which directly target the 3′‐UTR of TNFSF15. Additionally, we show that two VEGF‐stimulated cell growth signals, Erk and Akt, are responsible for promoting the expression of miR‐20a and miR‐31. Treatment of human umbilical vein endothelial cells (HUVECs) with Akt inhibitor LY294002 results in diminished miR‐20a and miR‐31 production, while Erk inhibitor U0126 prevented VEGF‐stimulated expression of miR‐20a but not that of miR‐31. Furthermore, inactivation of either Erk or Akt signals restores TNFSF15 gene expression. In an angiogenesis assay, elevated miR‐20a or miR‐31 levels in HUVECs leads to enhancement of capillary‐like tubule formation in vitro, whereas lowered miR‐20a and miR‐31 levels results in an inhibition. These findings are consistent with the view that miR‐20a and miR‐31 mediate VEGF‐induced downregulation of TNFSF15. Targeting these microRNA molecules may therefore provide an effective approach to inhibit angiogenesis.

Changes in TL1A levels and associated cytokines during pathogenesis of diabetic retinopathy

Tumor necrosis factor (TNF) ligand related molecule 1A (TL1A), also termed TNF superfamily member 15 and vascular endothelial growth inhibitor is important for tumorigenicity and autoimmunity. However, the function of TL1A in diabetic retinopathy (DR) remains to be elucidated. The present study established a diabetes mellitus (DM) rat model to investigate TL1A, vascular endothelial growth factor (VEGF), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) expression levels in the retina, vitreous and serum of rats with DM at different stages (1 month group, 3 month group and 6 month group). The present study determined that TL1A expression levels in the retina and vitreous from the DM 1 month group were significantly lower compared with the control group. However, TL1A levels in the retina and vitreous were significantly increased in advanced stages of DM compared with the control group. Furthermore, the levels of VEGF in the retina and vitreous were significantly higher in the DM groups compared with the control group. The expression levels of TNF-α and IL-1β in the retina and vitreous were significantly higher in DM 3 month and 6 month groups compared with the control group. It is of note that the expression levels of TL1A were significantly lower in the DM 1 and 3 month groups compared with the control group; however, they were significantly increased in the DM 6 month group compared with the DM 3 month group. The expression levels of VEGF, TNF-α and IL-1β in blood serum have been observed to exhibit similar expression change dynamics as those of the retina and vitreous. Therefore, these findings suggest that TL1A may be a protective factor of DR, and may provide a rationale for the development of novel therapeutic strategies to treat DR.

TNFSF15 Inhibits Blood Retinal Barrier Breakdown Induced by Diabetes

Tumor necrosis factor superfamily 15 (TNFSF15) is an endogenous neovascularization inhibitor and an important negative regulator of vascular homeostasis. This study aimed to explore the potential role of TNFSF15 in diabetic retinopathy. Vitreous TNFSF15 and VEGF levels in proliferative diabetic retinopathy (PDR) patients were detected by ELISA. Retinal expression of TNFSF15 and the content of tight junction proteins (TJPs) in rats were detected by immunohistochemistry and Western blot, respectively. The blood retinal barrier (BRB) permeability was evaluated using Evans Blue (EB) dye. The TNFSF15/VEGF ratio was decreased in the vitreous fluid of patients with PDR relative to the controls, even though the expression levels of TNFSF15 were higher. TNFSF15 was dramatically decreased one month later after diabetes induction (p < 0.001), and then increased three months later and thereafter. TNFSF15 treatment significantly protected the BRB in the diabetic animals. Diabetes decreased TJPs levels in the retina, and these changes were inhibited by TNFSF15 treatment. Moreover, TNFSF15 decreased activation of VEGF both in mRNA and protein levels caused by diabetes. These results indicate that TNFSF15 is an important inhibitor in the progression of DR and suggest that the regulation of TNFSF15 shows promise for the development of diabetic retinopathy treatment strategies.

NDRG1 overexpressing gliomas are characterized by reduced tumor vascularization and resistance to antiangiogenic treatment

Hypoxia-regulated molecules play an important role in vascular resistance to antiangiogenic treatment. N-myc downstream-regulated-gene 1 (NDRG1) is significantly upregulated during hypoxia in glioma. It was the aim of the present study to analyze the role of NDRG1 on glioma angiogenesis and on antiangiogenic treatment. Orthotopically implanted NDRG1 glioma showed reduced tumor growth and vessel density compared to controls. RT-PCR gene array analysis revealed a 30-fold TNFSF15 increase in NDRG1 tumors. Consequently, the supernatant from NDRG1 transfected U87MG glioma cells resulted in reduced HUVEC proliferation, migration and angiogenic response in tube formation assays in vitro. This effect was provoked by increased TNFSF15 promoter activity in NDRG1 cells. Mutations in NF-κB and AP-1 promoter response elements suppressed TNFSF15 promoter activity. Moreover, U87MG glioma NDRG1 knockdown supernatant contained multiple proangiogenic proteins and increased HUVEC spheroid sprouting. Sunitinib treatment of orhotopically implanted mice reduced tumor volume and vessel density in controls; in NDRG1 overexpressing cells no reduction of tumor volume or vessel density was observed. NDRG1 overexpression leads to reduced tumor growth and angiogenesis in experimental glioma via upregulation of TNFSF15. In NDRG1 overexpressing glioma antiangiogenic treatment does not yield a therapeutic response.

Functional genetic variants of TNFSF15 and their association with gastric adenocarcinoma: a case-control study

The purpose of this study was to identify functional genetic variants in the promoter of tumor necrosis factor superfamily member 15 (TNFSF15) and evaluate their effects on the risk of developing gastric adenocarcinoma. Forty DNA samples from healthy volunteers were sequenced to identify single nucleotide polymorphisms (SNPs) in the TNFSF15 promoter. Two TNFSF15 SNPs (−358T>C and −638A>G) were identified by direct sequencing. Next, genotypes and haplotypes of 470 gastric adenocarcinoma patients and 470 cancer-free controls were analyzed. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression. Serologic tests for Helicobacter pylori infection were measured by enzyme-linked immuno-sorbent assay (ELISA). Subjects carrying the TNFSF15 −358CC genotype were at an elevated risk for developing gastric adenocarcinoma, compared with those with the −358TT genotype (OR 1.42, 95% CI, 1.10 to 2.03). H. pylori infection was a risk factor for developing gastric adenocarcinoma (OR 2.31, 95% CI, 1.76 to 3.04). In the H. pylori infected group, subjects with TNFSF15 −358CC genotype were at higher risks for gastric adenocarcinoma compared with those carrying −358TT genotype (OR: 2.01, 95%CI: 1.65 to 4.25), indicating that H. pylori infection further influenced gastric adenocarcinoma susceptibility. The −358 T>C polymorphism eliminates a nuclear factor Y (NF-Y) binding site and the −358C containing haplotypes showed significantly decreased luciferase expression compared with −358T containing haplotypes. Collectively these findings indicate that functional genetic variants in TNFSF15 may play a role in increasing susceptibility to gastric adenocarcinoma.

In vivo NIRF imaging-guided delivery of a novel NGR-VEGI fusion protein for targeting tumor vasculature

Pathological angiogenesis is crucial in tumor growth, invasion and metastasis. Previous studies demonstrated that the vascular endothelial growth inhibitor (VEGI), a member of the tumor necrosis factor superfamily, can be used as a potent endogenous inhibitor of tumor angiogenesis. Molecular probes containing the asparagine-glycine-arginine (NGR) sequence can specifically bind to CD13 receptor which is overexpressed on neovasculature and several tumor cells. Near-infrared fluorescence (NIRF) optical imaging for targeting tumor vasculature offers a noninvasive method for early detection of tumor angiogenesis and efficient monitoring of response to anti-tumor vasculature therapy. The aim of this study was to develop a new NIRF imaging probe on the basis of an NGR-VEGI protein for the visualization of tumor vasculature. The NGR-VEGI fusion protein was prepared from prokaryotic expression, and its function was characterized in vitro. The NGR-VEGI protein was then labeled with a Cy5.5 fluorophore to afford Cy5.5-NGR-VEGI probe. Using the NIRF imaging technique, we visualized and quantified the specific delivery of Cy5.5-NGR-VEGI protein to subcutaneous HT-1080 fibrosarcoma tumors in mouse xenografts. The Cy5.5-NGR-VEGI probe exhibited rapid HT-1080 tumor targeting, and highest tumor-to-background contrast at 8 h post-injection (pi). Tumor specificity of Cy5.5-NGR-VEGI was confirmed by effective blocking of tumor uptake in the presence of unlabeled NGR-VEGI (20 mg/kg). Ex vivo NIRF imaging further confirmed in vivo imaging findings, demonstrating that Cy5.5-NGR-VEGI displayed an excellent tumor-to-muscle ratio (18.93 ± 2.88) at 8 h pi for the non-blocking group and significantly reduced ratio (4.92 ± 0.75) for the blocking group. In conclusion, Cy5.5-NGR-VEGI provided highly sensitive, target-specific, and longitudinal imaging of HT-1080 tumors. As a novel theranostic protein, Cy5.5-NGR-VEGI has the potential to improve cancer treatment by targeting tumor vasculature.

Death receptor 3 mediates TNFSF15- and TNFα-induced endothelial cell apoptosis

Tumor necrosis factor superfamily 15 (TNFSF15) suppresses angiogenesis by specifically inducing apoptosis in proliferating endothelial cells. Death receptor 3 (DR3), a member of the TNF receptor superfamily (TNFRSF25), has been identified as a receptor for TNFSF15 to activate T cells. It is unclear, however, whether DR3 mediates TNFSF15 activity on endothelial cells. Here we show that siRNA-mediated knockdown of DR3 in an in vivo Matrigel angiogenesis assay, or in adult bovine aortic endothelial (ABAE) cell cultures, leads to resistance of endothelial cells to TNFSF15-induced apoptosis. Interestingly, DR3-depleted cells also exhibited markedly diminished responsiveness to TNFα cytotoxicity, even though DR3 is not a receptor for TNFα. Treatment of the cells with either TNFSF15 siRNA or a TNFSF15-neutralizing antibody, 4-3H, also results in a significant inhibition of TNFα-induced apoptosis. Mechanistically, DR3 siRNA treatment gives rise to an increase of ERK1/2 MAPK activity, and up-regulation of the anti-apoptotic proteins c-FLIP and Bcl-2, thus strengthening apoptosis-resisting potential in the cells. These findings indicate that DR3 mediates TNFSF15-induced endothelial cell apoptosis, and that up-regulation of TNFSF15 expression stimulated by TNFα is partly but significantly responsible for TNFα-induced apoptosis in endothelial cells.

Interferon-γ produced by tumor-infiltrating NK cells and CD4+ T cells downregulates TNFSF15 expression in vascular endothelial cells

Endothelial cells in an established vasculature secrete tumor necrosis factor superfamily-15 (TNFSF15; VEGI; TL1A) that functions as a negative modulator of neovascularization to maintain blood vessel stability. TNFSF15 gene expression diminishes at angiogenesis and inflammation sites such as in cancers and wounds. We reported previously that vascular endothelial growth factor and monocyte chemotactic protein-1 contribute to TNFSF15 downmodulation in ovarian cancer. Here we show that interferon-γ (IFNγ) suppresses TNFSF15 expression in human umbilical vein endothelial cells. This activity is mediated by IFNγ receptor and the transcription factor STAT1. Immunohistochemical analysis of ovarian cancer clinical specimens indicates that TNFSF15 expression diminishes while tumor vascularity increases in specimens with high-grades of IFNγ expression. Since tumor-infiltrating NK and CD4(+) T cells are the main sources of IFNγ in tumor lesions, we isolated these cells from peripheral blood of healthy individuals, treated the cells with ovarian cancer OVCAR3 cell-conditioned media, and found a onefold and tenfold increase of IFNγ production in NK and CD4(+) T cells, respectively, compared with that in vehicle-treated cells. These findings support the view that tumor-infiltrating NK and CD4(+) T cells under the influence of cancer cells significantly increase the production of IFNγ, which in turn inhibits TNFSF15 expression in vascular endothelial cells, shifting the balance of pro- and anti-angiogenic factors toward escalated angiogenesis potential in the tumor.

Suppression of renal cell carcinoma growth in vivo by forced expression of vascular endothelial growth inhibitor

Vascular endothelial growth inhibitor (VEGI) has been associated with tumor-related vasculature in certain malignancies. However, its implication in renal cell carcinoma (RCC), an angiogenesis-dependent tumor, remains unknown. In the present study, we investigated the role played by VEGI in RCC. The expression of VEGI was examined in human renal tissue and RCC cell lines using immunohistochemical staining and RT-PCR, respectively. The biological impact of modifying the expression of VEGI in RCC cells was evaluated using in vitro and in vivo models. We show that VEGI mRNA is expressed in a wide variety of human RCC cell lines, all of normal renal and most of RCC tissue specimens. VEGI protein expression was observed in normal renal tubular epithelial cells, but was decreased or absent in RCC specimens, particularly in tumors with high grade. Moreover, forced expression of VEGI led to an inhibition of vascular endothelial tube formation, decrease in the motility and adhesion of RCC cells in vitro. Interestingly, forced expression of VEGI had no bearing on growth, apoptosis and invasive capacity of RCC cells. However, tumor growth was reduced in xenograft models. Immunohistochemical staining showed that microvessel density decreased in VEGI forced expression xenograft tumor samples. Taken together, our findings showed that the expression of VEGI is decreased in RCC, particularly in tumors with higher grade. Together with its inhibitory effect on cellular motility, adhesion, vascular endothelial tube formation and tumor growth in vivo, this suggests that VEGI functions mainly through inhibition of angiogenesis and is a negative regulator of aggressiveness during the development and progression of RCC.

Expression of death receptor-3 in human breast cancer and its functional effects on breast cancer cells in vitro

Death receptor-3 (DR3) plays controversial roles in cancer. Currently, DR3 is known to be a functional receptor of vascular endothelial growth inhibitor (VEGI). The role of DR3 in breast cancer remains unclear. The present study investigated DR3 expression in a clinical cohort of breast cancer patients and its role in breast cancer cells in vitro. The expression of DR3 was examined in a breast cancer cohort using quantitative PCR (Q-PCR) and immunohistochemistry (IHC) in comparison to the patients' data. In vitro function of DR3 was examined through the targeting of this molecule in MCF7 and MDA-MB-231 breast cancer cells using ribozyme transgene technology. Decreased DR3 expression was noted in breast cancer tissues compared to normal tissues and decreased expression of DR3 was generally associated with a poorer prognosis as well as a significantly shorter long-term survival (p=0.038). Targeting of DR3 in vitro in breast cancer cell lines resulted in impaired migratory rates compared to respective control cells. Collectively, these data suggest a complex role for DR3 in breast cancer development and progression.

TNFSF15 Modulates Neovascularization and Inflammation

Tumor necrosis factor superfamily-15 (TNFSF15; also known as VEGI or TL1A) is a unique cytokine that functions in the modulation of vascular homeostasis and inflammation. TNFSF15 is expressed abundantly in established vasculature but is down-regulated at sites of neovascularization such as in cancers and wounds. TNFSF15 inhibits endothelial cell proliferation and endothelial progenitor cell differentiation. Additionally, TNFSF15 stimulates T cell activation, Th1 cytokine production, and dendritic cell maturation. Some of the functions of TNFSF15 are mediated by death receptor-3. We review the experimental evidences on TNFSF15 activities in angiogenesis, vasculogenesis, inflammation, and immune system mobilization.

Dual function of RGD-modified VEGI-192 for breast cancer treatment

Identification of endogenous angiogenesis inhibitors has led to development of an increasingly attractive strategy for cancer therapy and other angiogenesis-driven diseases. Vascular endothelial growth inhibitor (VEGI), a potent and relatively nontoxic endogenous angiogenesis inhibitor, has been intensively studied, and this work shed new light on developing promising anti-angiogenic strategies. It is well-documented that the RGD (Arg-Gly-Asp) motif exhibits high binding affinity to integrin α(v)β(3), which is abundantly expressed in cancer cells and specifically associated with angiogenesis on tumors. Here, we designed a fusion protein containing the special RGD-4C motif sequence and VEGI-192, aimed at offering more effective multiple targeting to tumor cells and tumor vasculature, and higher anti-angiogenic and antitumor efficacy. Functional tests demonstrated that the purified recombinant human RGD-VEGI-192 protein (rhRGD-VEGI-192) potently inhibited endothelial growth in vitro and suppressed neovascularization in chicken chorioallantoic membrane in vivo, to a higher degree as compared with rhVEGI-192 protein. More importantly, rhRGD-VEGI-192, but not rhVEGI-192 protein, could potentially target MDA-MB-435 breast tumor cells, significantly inhibiting growth of MDA-MB-435 cells in vitro, triggered apoptosis in MDA-MB-435 cells by activation of caspase-8 as well as caspase-3, which was mediated by activating the JNK signaling associated with upregulation of pro-apoptotic protein Puma, and consequently led to the observed significant antitumor effect in vivo against a human breast cancer xenograft. Our study indicated that the RGD-VEGI-192 fusion protein might represent a novel anti-angiogenic and antitumor strategy.

Down-modulation of TNFSF15 in ovarian cancer by VEGF and MCP-1 is a pre-requisite for tumor neovascularization

Persistent inflammation and neovascularization are critical to cancer development. In addition to upregulation of positive control mechanisms such as overexpression of angiogenic and inflammatory factors in the cancer microenvironment, loss of otherwise normally functioning negative control mechanisms is likely to be an important attribute. Insights into the down-modulation of such negative control mechanisms remain largely unclear, however. We show here that tumor necrosis factor superfamily-15 (TNFSF15), an endogenous inhibitor of neovascularization, is a critical component of the negative control mechanism that operates in normal ovary but is missing in ovarian cancer. We show in clinical settings that TNFSF15 is present prominently in the vasculature of normal ovary but diminishes in ovarian cancer as the disease progresses. Vascular endothelial growth factor (VEGF) produced by cancer cells and monocyte chemotactic protein-1 (MCP-1) produced mainly by tumor-infiltrating macrophages and regulatory T cells effectively inhibits TNFSF15 production by endothelial cells in vitro. Using a mouse syngeneic tumor model, we demonstrate that silencing TNFSF15 by topical shRNA treatments prior to and following mouse ovarian cancer ID8 cell inoculation greatly facilitates angiogenesis and tumor growth, whereas systemic application of recombinant TNFSF15 inhibits angiogenesis and tumor growth. Our findings indicate that downregulation of TNFSF15 by cancer cells and tumor infiltrating macrophages and lymphocytes is a pre-requisite for tumor neovascularization.

Aberrant expression and function of death receptor-3 and death decoy receptor-3 in human cancer

Death receptor-3 (DR3) and death decoy receptor-3 (DcR3) are both members of the tumour necrosis factor receptor (TNFR) superfamily. The TNFR superfamily contains eight death domain-containing receptors, including TNFR1 (also called DR1), Fas (also called DR2), DR3, DR4, DR5, DR6, NGFR and EDAR. Upon the binding of these receptors with their corresponding ligands, the death domain recruits various proteins that mediate both the death and proliferation of cells. Receptor function is negatively regulated by decoy receptors (DcR1, DcR2, DcR3 and OPG). DR3/DcR3 are a pair of positive and negative players with which vascular endothelial growth inhibitor (VEGI) interacts. VEGI has been suggested to be a potential tumour suppressor. The inhibitory effects of VEGI on cancer are manifested in three main areas: a direct effect on cancer cells, an anti-angiogenic effect on endothelial cells, and the stimulation of dendritic cell maturation. A recent study indicated that DR3 may be a new receptor for E-selectin, which has been reported to be associated with cancer metastasis. DcR3 is a soluble receptor, highly expressed in various tumours, which lacks an apparent transmembrane segment, prevents cytokine response through ligand binding and neutralization, and is an inhibitor of apoptosis. DcR3 serves as a decoy receptor for FasL, LIGHT and VEGI. The cytokine LIGHT activates various anti-tumour functions and is expected to be a promising candidate for cancer therapy. Certain tumours may escape FasL-dependent immune-cytotoxic attack by expressing DcR3, which blocks FasL function. DR3/DcR3 play profound roles in regulating cell death and proliferation in cancer. The present review briefly discusses DR3/DcR3 and attempts to elucidate the role of these negative and positive players in cancer.

LITAF and TNFSF15, two downstream targets of AMPK, exert inhibitory effects on tumor growth

Lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) α factor (LITAF) is a multiple functional molecule whose sequence is identical to the small integral membrane protein of the lysosome/late endosome. LITAF was initially identified as a transcription factor that activates transcription of proinflammatory cytokine in macrophages in response to LPS. Mutations of the LITAF gene are associated with a genetic disease, called Charcot-Marie-Tooth syndrome. Recently, we have reported that mRNA levels of LITAF and TNF superfamily member 15 (TNFSF15) are upregulated by 5' adenosine monophosphate (AMP)-activated protein kinase (AMPK). The present study further assesses their biological functions. Thus, we show that 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), a pharmacological activator of AMPK, increases the abundance of LITAF and TNFSF15 in LNCaP and C4-2 prostate cancer cells, which is abrogated by small hairpin RNA (shRNA) or the dominant-negative mutant of AMPK α1 subunit. Our data further demonstrate that AMPK activation upregulates the transcription of LITAF. Intriguingly, silencing LITAF by shRNA enhances proliferation, anchorage-independent growth of these cancer cells and tumor growth in the xenograft model. In addition, our study reveals that LITAF mediates the effect of AMPK by binding to a specific sequence in the promoter region. Furthermore, we show that TNFSF15 remarkably inhibits the growth of prostate cancer cells and bovine aortic endothelial cells in vitro, with a more potent effect toward the latter. In conjuncture, intratumoral injection of TNFSF15 significantly reduces the size of tumors and number of blood vessels and induces changes that are characteristic of tumor cell differentiation. Therefore, our studies for the first time establish the regulatory axis of AMPK-LITAF-TNFSF15 and also suggest that LITAF may function as a tumor suppressor.

Vascular endothelial growth inhibitor (VEGI; TNFSF15) inhibits bone marrow-derived endothelial progenitor cell incorporation into Lewis lung carcinoma tumors

Bone marrow (BM)-derived endothelial progenitor cells (EPC) have a critical role in tumor neovascularization. Vascular endothelial growth inhibitor (VEGI) is a member of the TNF superfamily (TNFSF15). We have shown that recombinant VEGI suppresses tumor angiogenesis by specifically eliminating proliferating endothelial cells (EC). We report here that treatment of tumor bearing mice with recombinant VEGI leads to a significantly decreased population of BM-derived EPC in the tumors. We transplanted whole bone marrow from green fluorescent protein (GFP) transgenic mice into C57BL/6 recipient mice, which were then inoculated with Lewis lung carcinoma (LLC) cells. Intraperitoneal injection of recombinant VEGI led to significant inhibition of tumor growth and decrease of vasculature density compared to vehicle-treated mice. Tumor implantation yielded a decrease of BM-derived EPC in the peripheral blood, while VEGI-treatment resulted in an initial delay of such decrease. Analysis of the whole bone marrow showed a decrease of Lin(-)-c-Kit(+)-Sca-1(+) hematopoietic stem cell (HSC) population in tumor bearing mice; however, VEGI-treatment caused a significant increase of this cell population. In addition, the number of BM-derived EPC in VEGI-treated tumors was notably less than that in the vehicle-treated group, and most of the apoptotic cells in the VEGI-treated tumors were of bone marrow origin. These findings indicate that VEGI inhibits BM-derived EPC mobilization and prevents their incorporation into LLC tumors by inducing apoptosis specifically of BM-derived cells, resulting in the inhibition of EPC-supported tumor vasculogenesis and tumor growth.

Inhibition of corneal neovascularization by vascular endothelia growth inhibitor gene

AIM

To evaluate the effect of Effectene™ lipofectine mediated plasmids encoding human pcDNA(4)-vascular endothelia growth inhibitor (pcDNA(4)-VEGI) gene on corneal neovascularization (CNV).

METHODS

Forty New Zealand albino rabbits were sutured by 5-0 silk on the superior cornea to induce CNV and divided into 4 random teams, ten per each team: team A: transfected by pcDNA(4)-VEGI gene mediated by Effectene(™) lipofectine transfection; team B: by plasmid pcDNA(4); team C: by Effectene(™), and team D: by normal saline. Length and area of CNV were observed under slit lamp every day after transfection. Immunohistochemistry was performed to detect the expression of VEGI protein in corneas at day 3, 7, 14 and 21.

RESULTS

1) Average occurrence of CNV was 6.3 days in team A, 3.1 days in team B, 3.2 days in team C, and 3.2 days in team D. Difference was significant between A and other teams (P<0.01); 2) Length and average area of CNV in each period in team A was significantly different from those in team B, C and D (P<0.01); 3) VEGI expressions were observed in epithelium, stroma, endothelium and the cliff of CNV in team A at 3 days after transfection by immunohistochemical staining. None VEGI positive cells were found in the control teams (team B, C and D) all the time.

CONCLUSION

Effectene(™) lipofectine transfection technique can effectively transfect pcDNA(4)-VEGI gene into rabbit cornea and the length and CNV areas can be inhibited by VEGI gene.

Approaches to efficient production of recombinant angiogenesis inhibitor rhVEGI-192 and characterization of its structure and antiangiogenic function

Methods to prepare pure, bioactive recombinant human vascular endothelial growth inhibitor (rhVEGI), a potent inhibitor of angiogenesis potentially applicable in antiangiogenic cancer therapy, are in urgent demand for preclinical investigation as well as future clinical trials of the protein. Here, we report expression and purification of rhVEGI-192, a recombinant VEGI isoform, comparatively using host strains BL21 (DE3) pLysS and Origami B (DE3) with IPTG-induction and autoinduction techniques. Our study identified that a combined use of Origami B (DE3) strain and autoinduction expression system gave rise to a high yield of purified rhVEGI-192 at 105.38 mg/L culture by immobilized-metal affinity chromatography on Ni-NTA column. The antiangiogenic activity was effectively restored after the insoluble fractions being dissolved in 8M urea and subsequently subjected to a gradient-dialysis refolding process. Functional tests demonstrated that the purified rhVEGI-192 potently inhibited endothelial growth, induced endothelial apoptosis and suppressed neovascularization in chicken chorioallantoic membrane, indicating that the developed method allows preparation of rhVEGI-192 with high yield, solubility, and bioactivity. Most importantly, our study also demonstrates that VEGI-192 is capable of forming polymeric structure, which is possibly required for its antiangiogenic activity.

The Chick Embryo Chorioallantoic Membrane as an In Vivo Assay to Study Antiangiogenesis

Antiangiogenesis, e.g., inhibition of blood vessel growth, is being investigated as a way to prevent the growth of tumors and other angiogenesis-dependent diseases. Pharmacological inhibition interferes with the angiogenic cascade or the immature neovasculature with synthetic or semi-synthetic substances, endogenous inhibitors or biological antagonists.The chick embryo chorioallantoic membrane (CAM) is an extraembryonic membrane, which serves as a gas exchange surface and its function is supported by a dense capillary network. Because its extensive vascularization and easy accessibility, CAM has been used to study morphofunctional aspects of the angiogenesis process in vivo and to study the efficacy and mechanism of action of pro- and anti-angiogenic molecules. The fields of application of CAM in the study of antiangiogenesis, including our personal experience, are illustrated in this review article.

Inhibition of corneal neovascularization by vascular endothelia growth inhibitor gene

AIM

To evaluate the effect of Effectene™ lipofectine mediated plasmids encoding human pcDNA4-vascular endothelia growth inhibitor (pcDNA(4)-VEGI) gene on corneal neovascularization (CNV).

METHODS

Forty New Zealand albino rabbits were sutured by 5-0 silk on the superior cornea to establish the animal model and divided into 4 random group, ten per each group: group A: transfected by pcDNA(4)-VEGI gene mediated by Effectene™ lipofectine transfection, group B: by Plasmid pcDNA(4), group C: by Effectene™, and group D: by normal saline. Length and area of CNV were measured under slit lamp every day after transfection, immunohistochemistry was used to detected the expression of VEGI protein in cornea at 3, 7, 14 and 21 days.

RESULTS

Average occurrence of CNV in the pcDNA(4)-VEGI gene transfected group (group A) was 6.3 days, in plasmid pcDNA(4) control group (group B) was 3.1 days, in Effectene™ lipofectine control group (group C) was 3.2 days, in normal saline control group (group D) was 3.2 days. Differences between groups A and B, C, D were statistically significant (P<0.01), while differences in groups B, C and D were meaningless (P>0.05). Lenth and average area of CNV in each period in group A was meaningful different from that in groups B, C, and D (P<0.01), while differences in group B, C and D were meaningless (P>0.05). Immunohistochemistry result: VEGI positive cells could be seen in epithelium, stroma, endothelium and the cliff of CNV in group A at 3 days after transfection. VEGI cells changed with the decrease of CNV. None positive cells were in the control groups (groups B, C and D) all the time.

CONCLUSION

Effectene™ lipofectine transfection technique can be effectively used in transfecting pcDNA(4)-VEGI gene into rabbit cornea and the lenth and areas of CNV can be inhibited by VEGI gene.

Sensitization of endothelial cells to VEGI-induced apoptosis by inhibiting the NF-kappaB pathway

Vascular endothelial growth inhibitor (VEGI) is an endogenous inhibitor of endothelial cell growth and a promising candidate for cancer therapy. VEGI is able to inhibit tumor growth by specifically targeting the tumor neovasculature. Increasing the anti-angiogenic potential of this cytokine is of great interest for its therapeutic potential. NF-kappaB is known to have an integral role in TNF superfamily signaling, acting as a pro-survival factor. A role of VEGI-induced NF-kappaB activation in endothelial cells has yet to be described. Here we show that suppression of the NF-kappaB pathway can increase the apoptotic potential of VEGI. We used siRNA to deplete NF-kappaB or its activator IKK2 from adult bovine aortic endothelial cells. The siRNA treatments diminished VEGI-induced NF-kappaB activation, evidenced from a reduced extent of NF-kappaB nuclear translocation and diminished expression of NF-kappaB-target genes such as interleukins-6 and -1beta. The siRNA-treated endothelial cells when exposed to VEGI exhibited a marked decrease in cell viability and a significant increase in apoptosis. These results confirm that VEGI utilizes NF-kappaB as a pro-survival role factor in endothelial cells. We then examined whether a combination of VEGI with NF-kappaB inhibitors would constitute a more potential therapeutic regiment. We found that in the presence of the NF-kappaB inhibitors curcumin or BMS-345541 there was a marked increase in the apoptotic potential of VEGI on endothelial cells. These findings indicate that a combination therapy using VEGI and NF-kappaB inhibitors could be a potent approach for cancer treatment.

Amperometric micro-immunosensor for the detection of tumor biomarker

In this paper, a highly sensitive, reagentless, electrochemical strategy is reported for the detection of a cancer biomarker-Vascular Endothelial Growth Factor (VEGF). Disc shaped carbon fiber microelectrodes were used as the immunosensor platform. Ferrocene monocarboxylic acid labeled anti-VEGF was covalently immobilized on the microelectrode surface using a Jeffamine cross-linker. The formation of immunocomplexes leads to a decrease in the electrochemical signal of ferrocene monocarboxylic acid owing to increased spatial blocking of microelectrode surface. These signal changes enable quantitative detection of VEGF in solution. Voltammetric measurements were conducted to evaluate the interfacial immunoreactions and to quantitatively detect VEGF biomarker. The proposed immunosensing strategy allows a rapid and sensitive means of VEGF analysis with a limit of detection of about 38 pg/mL. This opens up the possibility of employing these electrodes for various single cell analysis and clinical applications. Further, experimental conditions such as concentration of the immobilized antibodies and incubation period were optimized. Following this, the stability and specificity of the immunosensors were also evaluated.

Inhibition of endothelial progenitor cell differentiation by VEGI

Endothelial progenitor cells (EPCs) play a critical role in postnatal and tumor vasculogenesis. Vascular endothelial growth inhibitor (VEGI; TNFSF15) has been shown to inhibit endothelial cell proliferation by inducing apoptosis. We report here that VEGI inhibits the differentiation of EPCs from mouse bone marrow-derived Sca1(+) mononuclear cells. Analysis of EPC markers indicates a significant decline of the expression of endothelial cell markers, but not stem cell markers, on VEGI-treated cells. Consistently, the VEGI-treated cells exhibit a decreased capability to adhere, migrate, and form capillary-like structures on Matrigel. In addition, VEGI induces apoptosis of differentiated EPCs but not early-stage EPCs. When treated with VEGI, an increase of phospho-Erk and a decrease of phospho-Akt are detected in early-stage EPCs, whereas activation of nuclear factor-kappaB, jun N-terminal kinase, and caspase-3 is seen in differentiated EPCs. Furthermore, VEGI-induced apoptosis of differentiated EPC is, at least partly, mediated by death receptor-3 (DR3), which is detected on differentiated EPC only. VEGI-induced apoptosis signals can be inhibited by neutralizing antibodies against DR3 or recombinant extracellular domain of DR3. These findings indicate that VEGI may participate in the modulation of postnatal vasculogenesis by inhibiting EPC differentiation.

Preparation and characterization of a novel chimeric protein VEGI-CTT in Escherichia coli

Vascular endothelial cell growth inhibitor (VEGI) is a recently identified antiangiogenic cytokine that belongs to the TNF superfamily, and could effectively inhibit endothelial cell proliferation and angiogenesis. Synthetic peptide CTT (CTTHWGFTLC) has been found to suppress invasion and migration of both tumor and endothelial cells by potent and selective inhibition of MMP-2 and MMP-9. To prepare chimeric protein VEGI-CTT for more potent antitumor therapy, the recombinant expression vector pET-VEGI-CTT was constructed. This fusion protein was expressed in inclusion bodies in E. coli BL21 (DE3), and was refolded and purified by immobilized metal affinity chromatography using His-tag. Purified VEGI-CTT protein was characterized by proliferation assays of the endothelial cells and casein degradation assay in vitro. The results demonstrated that chimeric protein VEGI-CTT had a potent activity of antiangiogenesis through inhibiting the proliferation of endothelial cells, and could effectively reduce the activity of MMP-2 and MMP-9. The preliminarily in vivo study demonstrated that chimeric protein VEGI-CTT had more potent antitumor activity than VEGI and/or CTT peptide against CA46 human lymphoma xenografts in nude mice. Thus, these facts that are derived from the present study suggest that the chimeric protein VEGI-CTT may be used for tumor therapy in the future.

Comparative analysis of the expression patterns of various TNFSF/TNFRSF in atherosclerotic plaques

Members of the TNFSF/TNFRSF are involved in the immunoregulation of various immune reactions and diseases. Recently, LIGHT/TR2, GITRL/GITR, and TL1A/DR3 have been reported as playing roles in the inflammatory reactions in atherosclerosis, but a comparative analysis of these molecules has not been conducted. In order to compare their expression patterns, immunohistochemical analyses were performed using six human carotid endoarterectomy samples. The expression of these molecules was detected in the various cell types that constitute atherosclerotic plaques. The expression of all analyzed molecules was detected, albeit at various levels, mainly in foamy macrophages in all tested samples. The strong expression of these molecules in endothelial and smooth muscle cells was also detected in 2 and 1 plaque samples, respectively, while others express only some of the tested molecules. Flow cytometry analyses of human monocyte/macrophage cell lines, U937 and THP-1, detected the expression of the tested molecules while a relatively undifferentiated monocytic cell line, TF-1A, failed to express them. These data indicate that activated and differentiated macrophages are the main cell type expressing tested molecules in atherosclerotic plaques while endothelial and smooth muscle cells can express them in limited cases. Pro-inflammatory activities of the tested molecules may contribute to the atherogenesis by stimulating the cells expressing them in atherosclerotic plaques and the successful treatment of atherosclerosis may require cooperative regulation of these activities.

The endothelial cell-produced antiangiogenic cytokine vascular endothelial growth inhibitor induces dendritic cell maturation

Angiogenesis is an essential component of chronic inflammation that is linked to carcinogenesis. In this study, we report that human vascular endothelial growth inhibitor (VEGI, TNF superfamily 15), an endothelial cell-produced antiangiogenic cytokine, induces mouse dendritic cell (DC) maturation, a critical event in inflammation-initiated immunity. VEGI-stimulated bone marrow-derived immature DCs display early activation of maturation signaling molecules NF-kappaB, STAT3, p38, and JNK, and cytoskeleton reorganization and dendrite formation. The activation signals are partially inhibited by using a neutralizing Ab against death domain-containing receptor-3 (DR3) or a truncated form of DR3 consisting of the extracellular domain, indicating an involvement of DR3 in the transmission of VEGI activity. A VEGI isoform, TL1A, does not induce similar activities under otherwise identical experimental conditions. Additionally, the cells reveal significantly enhanced expression of mature DC-specific marker CD83, secondary lymphoid tissue-directing chemokine receptor CCR7, the MHC class-II protein (MHC-II), and costimulatory molecules CD40, CD80, and CD86. Functionally, the cells exhibit decreased Ag endocytosis, increased cell surface distribution of MHC-II, and increased secretion of IL-12 and TNF. Moreover, VEGI-stimulated DCs are able to facilitate the differentiation of CD4+ naive T cells in cocultures. These findings suggest that the anticancer activity of VEGI arises from coupling the inhibition of endothelial cell growth with the promotion of the adaptive immune mechanisms through the stimulation of DC maturation.

The role of vascular endothelial growth inhibitor in wound healing

Vascular endothelial growth inhibitor (VEGI) is an endothelial cell-specific cytokine and a potent inhibitor of endothelial cell proliferation and angiogenesis. The role of VEGI in angiogenesis related to tissue repair has previously not been investigated. Biopsies from different wound types were analysed by immunohistochemistry and quantitative polymerase chain reaction for the presence of VEGI protein and transcript, respectively. Human vascular endothelial cell line was transfected with VEGI expression plasmid and tested for their in vitro angiogenesis properties. Immunohistochemical staining for VEGI showed reduced expression in the dermal layer of the acute wounds compared with the chronic wound or normal skin. The ability of VEGI to prevent angiogenesis by in vitro assays showed that VEGI acts as a suppressor to the proliferation and microtubule formation of endothelial cells, and the addition of Hepatocyte Growth Factor had little effect on the ability of cell lines expressing the VEGI gene to increase microtubule formation. The aberrant expression of VEGI in different wound types appears to be linked to the outcome of the healing in these wounds. The altered expression of VEGI in chronic wounds constitutes an important target of future therapies.

Involvement of RB gene family in tumor angiogenesis

Angiogenesis, the development of new blood vessels from pre-existing vessels, represents a fundamental step in tumor progression and metastatization. The induction of vasculature is required for growth of the tumor mass, to ensure an adequate supply of oxygen and metabolites to the tumor beyond a critical size. Tumor angiogenesis is a highly regulated process that is controlled physiologically by the tumor microenvironment and genetically by alteration of several oncogenes or tumor suppressor genes. We will focus on recent demonstrations regarding the involvement of the retinoblastoma family proteins (phosphorylated retinoblastoma (pRb), p107 and pRb2/p130) at different levels of the angiogenic process. pRb and its homologs can regulate the expression of pro- and antiangiogenic factors, such as the vascular endothelial growth factor, through an E2F-dependent mechanism. Moreover, pRb is able to modulate also the transcriptional activity of several angiogenesis-related factors like HIF-1, Id2 and Oct-1. pRb2/p130 is required for both differentiation and mobilization of bone marrow-derived endothelial cell precursors and endothelial sprouting from neighboring vessels. The involvement of the pRb pathway in the angiogenesis process has also been demonstrated by different cellular models expressing viral oncoproteins, like human papilloma virus. Moreover, some natural and synthetic compounds demonstrate their antiangiogenetic activity with a mechanism of action involving pRb. Finally, the possible prognostic value of immunohistochemical evaluation of pRb and/or pRb2/p130 expression can represent a useful tool for the characterization of the angiogenic phenotype of specific tumor histotypes.

Reduced vascular endothelial growth inhibitor (VEGI) expression is associated with poor prognosis in breast cancer patients

Vascular endothelial growth inhibitor (VEGI) is a novel anti-angiogenic cytokine that belongs to the tumour necrosis factor (TNF) superfamily. Very little is known about the significance of VEGI in cancer. Our study analysed VEGI expression in relation to breast cancer patient clinical parameters. The VEGI expression profile was assessed qualitatively (RT-PCR), quantitatively (real-time Quantitative-PCR), and immuno-histochemically (IHC), in a panel of 24 human normal and cancer cell lines and in a cohort of 151 mammary tissue samples (n = 33 normal breast tissue; n = 118 breast cancer tissue) with a 6-year median follow-up. Patients who had died of breast cancer or had local recurrence of the disease expressed significantly lower levels of VEGI in comparison to the elevated levels in the disease free patients. High levels of VEGI were associated with an increased chance of patient survival. Importantly, patients with breast tumours expressing reduced levels of VEGI had a poorer prognosis than those patients expressing high levels of VEGI. However, no significant correlations were observed between VEGI expression and tumour grade, TNM classification, or nodal involvement. In conclusion, VEGI is aberrantly expressed in human breast cancer tissues. VEGI displays prognostic relevance as breast cancer patients with an overall poor prognosis express significantly lower levels of VEGI compared to those with a favourable prognosis.

Vascular endothelial growth inhibitor (VEGI), an endogenous negative regulator of angiogenesis

Vascular endothelial growth inhibitor (VEGI; TNFSF-15) is a new member of the tumor necrosis factor family. VEGI is predominantly an endothelial cell-specific gene, and recombinant VEGI is a potent inhibitor of endothelial cell proliferation, angiogenesis and tumor growth. VEGI exerts two activities on endothelial cells: early G1 arrest of G0/G1-cells responding to growth stimuli, and programmed death of proliferating cells. These activities are highly specific to endothelial cells. There are three VEGI isoforms identified thus far. One of the isoforms, VEGI-251, is a secreted protein. The gene products apparently play a role in normal vasculature, as the transcripts are found in normal adult tissues and some fetal tissues. VEGI gene expression is subject to regulation by inflammatory cytokines. VEGI is also able to regulate the expression of several important genes involved in angiogenesis. These findings are consistent with the view that VEGI functions as an autocrine cytokine to inhibit angiogenesis and stabilize the vasculature.

Isoform of vascular endothelial cell growth inhibitor (VEGI72-251) increases interleukin-2 production by activation of T lymphocytes

The objective of this study is to investigate the characteristics of the recombinant variant of human vascular endothelial cell growth inhibitor, VEGI72-251, and compare its biological activities with that of its prototype VEGI24-174. The recombinant plasmid containing the variant VEGI72-251 gene was constructed and expressed in Escherichia coli. The effects of the expressed VEGI72-251 on cell proliferations were checked in the human umbilical vein endothelial cell line and certain tumor cell lines (ECV304 and B16). The inhibition of VEGI72-251 on angiogenesis was detected in the chorioallantoic membrane of chick embryos. In comparison with VEGI24-174, the recombinant human VEGI72-251 seems to have no effect on the proliferation of endothelial cells and the angiogenesis of the chorioallantoic membrane in vitro. An enzyme-linked immunosorbent assay-based method was used for the measurement of interleukin-2 (IL-2) production by peripheral blood monocytes (PBMCs) treated with VEGI72-251. PBMCs were pretreated with VEGI72-251 (1.25-12.50 microg/ml) for 24 h in vitro, and the IL-2 concentration in PBMC medium was increased from 354 pg/ml to 1256 pg/ml. It can be concluded that VEGI72-251 is able to increase the level of human IL-2 production by the activation of T lymphocytes. Differing from VEGI24-174 on anti-angiogenesis, VEGI72-251 may serve as an anti-cancer factor through its activation of T lymphocytes.

VEGI-192, a new isoform of TNFSF15, specifically eliminates tumor vascular endothelial cells and suppresses tumor growth

PURPOSE

We determined the antiangiogenic and anticancer activity of VEGI-192, a new isoform of TNFSF15 (VEGI, TL1), with a Lewis lung cancer murine tumor model.

EXPERIMENTAL DESIGN

Recombinant human VEGI-192 was produced in Escherichia coli and purified to apparent homogeneity. The protein was given systemically via i.p., i.v., or s.c. injections to tumor-bearing C57BL/6 mice. Tumor growth rates, animal survival rates, and general toxicity were determined. Effect on endothelial cell/smooth muscle cell ratio of the tumor vasculature was analyzed.

RESULTS

Systemic administration of VEGI-192 gave rise to a marked inhibition of tumor growth. As much as 50% inhibition of the tumor growth rate was achieved with treatment initiated when the tumor volumes reached nearly 5% of the body weight. Inhibition of tumor formation was also observed when VEGI-192 was given at the time of tumor inoculation. Consistently, we observed an increased survival time of the treated animals. The VEGI-192-treated animals showed no liver or kidney toxicity. The treatment eliminated tumor endothelial cells but not vascular smooth muscle cells, which remained associated with a residual vascular structure consisting of the basement membrane. In addition, we carried out immunohistochemical analysis of rat kidneys and found that vascular endothelial cell growth inhibitor (VEGI) expression is largely limited to endothelial cells.

CONCLUSIONS

Our findings indicate that VEGI is an endogenous inhibitor of angiogenesis, and that systemic administration of the VEGI-192 isoform resulted in inhibition of tumor angiogenesis and growth.