Down-regulate VEGFR2 Expression Research Articles

Role of ROS-mediated PERK/ATF4 signaling activation in extracorporeal tube formation injury of human umbilical vein endothelial cells induced by cooking oil fume PM2.5 exposure

Cooking oil fume-derived PM2.5 (COF-PM2.5) is a major source of indoor air contamination in China, which has been demonstrated to be a hazard factor of cardiovascular and cerebrovascular diseases. This study aimed to investigate the role of ROS-mediated PERK/ATF4 signaling activation in COF-PM2.5-inhibited extracorporeal tube formation in human umbilical vein endothelial cells (HUVECs). HUVECs were treated with 100 μg/mL COF-PM2.5 at different times, with or without 100 nM PERK activity inhibitor GSK2606414 (GSK) or 200 μM antioxidant N-acetylcysteine (NAC) pretreatment. Our results showed that COF-PM2.5 exposure can inhibit extracorporeal tube formation and down-regulate VEGFR2 expression in HUVECs. Furthermore, our data indicated that COF-PM2.5 exposure can activate the PERK/ATF4 signaling in HUVECs. Mechanistically, pretreatment with GSK interdicted PERK/ATF4 signaling, thereby reversing COF-PM2.5-downregulated VEGFR2 protein expression in HUVECs. Furthermore, NAC reversed VEGFR2 expression downregulated induced by COF-PM2.5 by inhibiting the upregulation of intracellular ROS levels and PERK/ATF4 signaling in HUVECs. As above, COF-PM2.5 exposure could induce ROS release from HUVECs, which in turn activate the endoplasmic reticulum PERK/ATF4 signaling and inhibit tube formation of HUVECs.

DIX domain containing 1 (DIXDC1) modulates VEGFR2 level in vasculatures to regulate embryonic and postnatal retina angiogenesis

BackgroundIn sprouting angiogenesis, VEGFR2 level is regulated via a fine-tuned process involving various signaling pathways. Other than VEGF/VEGFR2 signaling pathway, Wnt/ β-catenin signaling is also important in vascular development. However, the crosstalk between these two signaling pathways is still unknown to date. In this study, we aimed to investigate the role of DIX domain containing 1 (DIXDC1) in vasculature, facilitating the crosstalk between VEGF/VEGFR2 and Wnt/ β-catenin signaling pathways.ResultsIn mice, DIXDC1 deficiency delayed angiogenesis at the embryonic stage and suppressed neovascularization at the neonatal stage. DIXDC1 knockdown inhibited VEGF-induced angiogenesis in endothelial cells in vitro by downregulating VEGFR2 expression. DIXDC1 bound Dishevelled Segment Polarity Protein 2 (Dvl2) and polymerized Dvl2 stabilizing VEGFR2 protein via its direct interaction. The complex formation and stability of VEGFR2 was potentiated by Wnt signaling. Moreover, hypoxia elevated DIXDC1 expression and likely modulated both canonical Wnt/β-catenin signaling and VEGFR2 stability in vasculatures. Pathological angiogenesis in DIXDC1 knockout mice was decreased significantly in oxygen-induced retinopathy (OIR) and in wound healing models. These results suggest that DIXDC1 is an important factor in developmental and pathological angiogenesis.ConclusionWe have identified DIXDC1 as an important factor in early vascular development. These results suggest that DIXDC1 represents a novel regulator of sprouting angiogenesis that links Wnt signaling and VEGFR2 stability and may have a potential role in pathological neovascularization.

Effects of components in stasis-resolving and collateral-dredging Chinese herbal medicines on angiogenesis and inflammatory response of human umbilical vein endothelial cells induced by VEGF

The present study investigated the mechanism of components in stasis-resolving and collateral-dredging Chinese herbal medicines, including scutellarin(Scu), paeonol(Pae), and hydroxy safflower yellow A(HSYA), in the treatment of psoriasis by regulating angiogenesis and inflammation. The human umbilical vein endothelial cells(HUVECs) cultured in vitro were divided into a normal group, a model group, a VEGFR tyrosine kinase inhibitor Ⅱ(VRI) group, and Scu, Pae, and HSYA groups with low, me-dium, and high doses. Cell viability was detected by the CCK-8 assay. Cell migration was detected by wound healing assay. Tube formation assay was used to measure the tube formation ability. Western blot was used to detect the protein expression of the VEGFR2/Akt/ERK1/2 signaling pathway. The secretion levels of inflammatory cytokines IFN-γ, IL-1β, IL-6, and TNF-α were detected by ELISA. The results showed that compared with the model group, all the Scu, Pae, and HSYA groups could reduce cell viability, inhibit cell migration and tube formation(P<0.05, P<0.01), and down-regulated the protein expression of VEGFR2, p-VEGFR2, Akt, p-Akt, ERK1/2, and p-ERK1/2. Scu and Pae could down-regulate VEGFR2 expression(P<0.05, P<0.01), while other groups only showed a downward trend. Scu and Pae significantly reduced IFN-γ and IL-6 levels(P<0.01), and HSYA significantly reduced the levels of IFN-γ, IL-1β, and IL-6(P<0.01). Scu, Pae, and HSYA had no significant effect on TNF-α. The results suggested that Scu, Pae, and HSYA may exert a therapeutic role in psoriasis-related angiogenesis and inflammation by inhibiting VEGFR2/Akt/ERK1/2 signaling pathway and inhibiting the secretion of IFN-γ, IL-1β, and IL-6.

Design, synthesis, and biological evaluation of tetrahydroisoquinoline-based diaryl urea derivatives for suppressing VEGFR-2 signaling

A novel structural series of tetrahydroisoquinoline-based compounds that incorporate the diaryl urea moiety was designed, synthesized, and biologically evaluated as suppressors of VEFGR-2 signaling. As a consequence, compounds 9k and 9s exhibited comparable or superior cytotoxic activity to that of gefitinib against the tested three cell lines, including A549, MCF-7, and PC-3. Importantly, both of them downregulated the expression of VEGFR-2, and inhibited VEGFR-2 phosphorylation at the concentration of 0.5 or 1.0 μmol/l. Besides, they suppressed human umbilical vein endothelial cell tube formation at the concentration of 4.0 μmol/l. Considering their capability of down-regulating VEGFR-2 expression and inhibiting VEGFR-2 phosphorylation, 9k and 9s may serve as suppressors of angiogenesis for further investigation.

Purple Sweet Potato Color Attenuates Kidney Damage by Blocking VEGFR2/ROS/NLRP3 Signaling in High-Fat Diet-Treated Mice.

Our preliminary data showed that VEGFR2 upregulation promoted renal ROS overproduction in high-fat diet- (HFD-) treated mice. Given that ROS-induced NLRP3 activation plays a central role in the pathogenesis of type 2 diabetic kidney injury, we evaluate whether VEGFR2 upregulation induces type 2 diabetic kidney injury via ROS-mediated NLRP3 activation and further explore the underlying mechanism. Our results showed that VEGFR2 knockdown decreased ROS overproduction, blocked NLRP3-dependent inflammation, and alleviated kidney damage in HFD-treated mice. Treatment with α-lipoic acid, a scavenger of ROS, lowered ROS overproduction and alleviated NLRP3-triggered kidney injury of HFD-treated mice. Collectively, the VEGFR2/ROS/NLRP3 signal is a critical therapeutic strategy for the kidney injury of HFD-treated mice. Purple sweet potato color (PSPC), a natural anthocyanin, can exert renal protection by inhibiting ROS in HFD-treated mice. Here, we provide a novel mechanism of PSPC against renal damage in HFD-treated mice by downregulating VEGFR2 expression.

PDGF-mediated mesenchymal transformation renders endothelial resistance to anti-VEGF treatment in glioblastoma

Angiogenesis is a hallmark of cancer. However, most malignant solid tumors exhibit robust resistance to current anti-angiogenic therapies that primarily target VEGF pathways. Here we report that endothelial-mesenchymal transformation induces glioblastoma (GBM) resistance to anti-angiogenic therapy by downregulating VEGFR-2 expression in tumor-associated endothelial cells (ECs). We show that VEGFR-2 expression is markedly reduced in human and mouse GBM ECs. Transcriptome analysis verifies reduced VEGFR-2 expression in ECs under GBM conditions and shows increased mesenchymal gene expression in these cells. Furthermore, we identify a PDGF/NF-κB/Snail axis that induces mesenchymal transformation and reduces VEGFR-2 expression in ECs. Finally, dual inhibition of VEGFR and PDGFR eliminates tumor-associated ECs and improves animal survival in GBM-bearing mice. Notably, EC-specific knockout of PDGFR-β sensitizes tumors to VEGF-neutralizing treatment. These findings reveal an endothelial plasticity-mediated mechanism that controls anti-angiogenic therapy resistance, and suggest that vascular de-transformation may offer promising opportunities for anti-vascular therapy in cancer.

Effects of Trehalose on VEGF-Stimulated Angiogenesis and Myofibroblast Proliferation: Implications for Glaucoma Filtration Surgery

To investigate whether trehalose inhibits VEGF-stimulated or inflammatory angiogenesis and the proliferation of myofibroblasts. Normal human dermal fibroblasts and human umbilical vein endothelial cells (HUVECs)were cocultured in trehalose-containing medium (2.5/5.0/7.5/10.0%) with or without VEGF (10 ng/mL). After 11 days, the area, length, joint, and path of neovascularization were evaluated. The effect of topical trehalose on corneal neovascularization was examined in vivo by treating Balb/c mice with alkali burn-induced corneal neovascularization. After 14 days of trehalose treatment, corneal vessels were visualized in flatmounts. The expressions of VEGFR2, phospho-VEGFR2, and vimentin were observed. Then a separate coculture model of the myofibroblasts and HUVECs was used to observe the morphologic changes of the myofibroblasts by trehalose. Furthermore, myofibroblasts were cultured with trehalose to examine the cytokeratin and E-cadherin expressions. In the in vitro models, there was a significant trehalose dose-dependent inhibition of neovascularization. In the in vivo alkali burn models, corneal neovascularization was significantly inhibited by treatments using ≥ 2.5% trehalose eyedrops. The expressions of VEGFR2, phospho-VEGFR2, and vimentin were downregulated by trehalose. When trehalose was added to the medium, the myofibroblasts were transformed into epithelial cell-like cells. The transformed myofibroblasts expressed cytokeratin but not E-cadherin. Trehalose prevents angiogenesis by partially downregulating VEGFR2 expression. In addition, trehalose inhibits the proliferation of myofibroblasts partially by inducing mesenchymal-epithelial transition. These findings suggest that trehalose has potential for use as a new agent that can control angiogenesis and fibrosis and potential for use in glaucoma surgery.