Expression Of Platelet-derived Growth Factor Receptor-β Research Articles

Correlation between mechanism of oxidized-low density lipoprotein-induced macrophage apoptosis and inhibition of target gene platelet derived growth factor receptor-β expression by microRNA-9

ABSTRACT This study was to explore the effects of oxidized-low density lipoprotein (ox-LDL) on the proliferation and apoptosis of macrophages, and the role of miRNA-9 in the targeted regulation of platelet-derived growth factor receptor-β (PDGFR-β) expression. Macrophage RAW264.7 cells were cultured and foamed with 100 mg/L ox-LDL to detect the cell proliferation and apoptosis and target protein expression levels. Subsequently, the miRNA-9 mimics and inhibitors were transfected to detect the expression level of PDGFR-β. The dual-luciferase reporter gene was predicted and applied to detect the target-binding effect of miRNA-9 and PDGFR-β in the cells. The results showed that ox-LDL could induce the foaming of macrophages RAW264.7, inhibit the cell proliferation, and promote the cell apoptosis. After ox-LDL induction, expression of Caspase-3 in macrophages RAW264.7 was up-regulated, and that of glucose regulated protein 78 was down-regulated. The transfection of miRNA-9 mimics could greatly inhibit the expression of PDGFR-β mRNA and proteins in the cells. In addition, the results of the dual-luciferase reporter gene showed that the ratio of luciferase activity was significantly reduced after the miRNA-9 mimic and the wild-type PDGFR-β plasmid were co-transfected. In summary, ox-LDL could induce foaming of macrophages and promote cell apoptosis, and miRNA-9 could target and bind to the 3ʹUTR region of PDGFR-β, thereby inhibiting the gene expression.

Monomeric α-synuclein induces blood–brain barrier dysfunction through activated brain pericytes releasing inflammatory mediators in vitro

Blood–brain barrier (BBB) disruption is often mediated by neuroinflammation, and occurs during various neurodegenerative diseases including Parkinson's disease (PD). PD is characterized by loss of dopaminergic neurons and aggregated α-synuclein protein in inclusions known as Lewy bodies. Misfolded α-synuclein has been implicated in neurodegeneration and neuroinflammation through activation of microglia and astrocytes. Pericytes are a key cellular regulator of the BBB, although it is not known if they participate in α-synuclein-associated PD pathology. Here, we investigated the impact of pericytes on BBB integrity in response to α-synuclein using rat brain endothelial cells (RBECs) co-cultured with rat brain pericytes (RBEC/pericyte co-culture). In RBEC/pericyte co-cultures, α-synuclein added to the abluminal chamber (where pericytes were grown) significantly increased RBEC permeability to sodium fluorescein. In contrast, it had no marked effect when added to the luminal chamber. In the absence of pericytes, both luminal and abluminal addition of α-synuclein failed to affect permeability of the RBEC monolayer. α-Synuclein did not self-assemble in culture media within 24 h, suggesting that monomeric α-synuclein can disrupt the BBB by interacting with pericytes. We found that in response to α-synuclein, pericytes, but not RBECs, released interleukin (IL)-1β, IL-6, monocyte chemotactic protein (MCP)-1, tumor necrosis factor (TNF)-α, and matrix metalloproteinase-9 (MMP-9). α-Synuclein did not affect platelet-derived growth factor (PDGF)-BB release from RBECs and PDGF receptor-β expression in pericytes. These results suggest that pericytes are more sensitive to monomeric α-synuclein than RBECs regarding release of various inflammatory cytokines/chemokines and MMP-9. Thus, monomeric α-synuclein-activated pericytes may contribute to BBB breakdown in patients with PD.

Optimization of the tumor microenvironment and nanomedicine properties simultaneously to improve tumor therapy.

Effective delivery of nanomedicines to tumor tissues depends on both the tumor microenvironment and nanomedicine properties. Accordingly, tumor microenvironment modification or advanced design of nanomedicine was emerging to improve nanomedicine delivery to tumors. However, few studies have emphasized the necessity to optimize the tumor microenvironment and nanomedicine properties simultaneously to improve tumor treatment. In the present study, imatinib mesylate (IMA) was used to normalize the tumor microenvironment including platelet-derived growth factor receptor-β expression inhibition, tumor vessel normalization, and tumor perfusion improvement as demonstrated by immunofluorescence staining. In addition, the effect of tumor microenvironment normalization on tumor delivery of nanomedicines with different sizes was carefully investigated. It was shown that IMA treatment significantly reduced the accumulation of nanoparticles (NPs) around 110 nm but enhanced the accumulation of micelles around 23 nm by in vivo fluorescence imaging experiment. Furthermore, IMA treatment limited the distribution of NPs inside tumors but increased that of micelles with a more homogeneous pattern. Finally, the anti-tumor efficacy study displayed that IMA pretreatment could significantly increase the therapeutic effects of paclitaxel-loaded micelles. All-together, a new strategy to improve nanomedicine delivery to tumor was provided by optimizing both nanomedicine size and the tumor microenvironment simultaneously, and it will have great potential in clinics for tumor treatment.

Prognostic significance of platelet-derived growth factor receptor-β expression in localized clear cell renal cell carcinoma.

We investigated the expression status of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF)-B and their receptors in organ-confined clear cell renal cell carcinoma (ccRCC) to evaluate their prognostic significance after radical surgery. In 758 consecutive patients diagnosed with pT1-2N0 ccRCC between 2007 and 2012, we prospectively investigated the expression levels of VEGF, PDGF-B, VEGF receptor (VEGFR) and PDGF receptor (PDGFR)-β via immunohistochemistry. Clinicopathologic parameters and expression of the angiogenic factors were analyzed with respect to recurrence-free survival (RFS) after nephrectomy. The median follow-up was 29.5 months (IQR 21.5, 39.6) after surgery. Partial nephrectomy had been performed in 48.5 % of the patients, and tumors were staged as pT1a in 514 (67.8 %), pT1b in 192 (25.3 %) and pT2 in 52 (6.9 %). VEGF, PDGF and their receptors were identified in the cytoplasm and membranes of the tumor cells. Expression level of VEGFR inversely correlated with both tumor size (r = -0.076, p = 0.014) and nuclear grade (r = -0.297, p = 0.004). As for PDGF-B, the expression level showed an inverse correlation with tumor size (r = -0.216, p < 0.001) while PDGFR-β inversely correlated with nuclear grade (r = -0.341, p = 0.001). On multivariate analysis, age, pathologic stage, nuclear grade and PDGFR-β expression (high vs. low or none, HR 3.121 95 % CI 1.300-7.493, p = 0.011) were independently prognostic of RFS after nephrectomy. In organ-confined ccRCC, high expression of PDGFR-β was independently predictive of poorer RFS after nephrectomy.

Predictive role of tissue-based molecular markers in patients treated with sunitinib for metastatic renal cell carcinoma

We analyzed the clinicopathological data of patients undergoing radical nephrectomy for clear cell type renal cell carcinoma (RCC) who presented with metastasis and were subsequently treated with sunitinib and identified molecular markers in nephrectomy specimens to predict susceptibility to sunitinib. The medical records of 65 patients who underwent nephrectomy for metastatic clear cell type RCC and were then treated with sunitinib were reviewed. The nephrectomy specimens were subjected to prospective immunohistochemical staining for vascular endothelial growth factor, vascular endothelial growth factor receptor-2 (VEGFR-2), platelet-derived growth factor-B, and platelet-derived growth factor receptor-β expression. In 58 evaluable patients, the median value of initial and best overall response was -9.69 and -24.04 %, respectively. VEGFR-2 expression was associated significantly with initial and best overall responses to sunitinib, along with Karnofsky performance status and Memorial Sloan-Kettering Cancer Center prognostic risk group. Multiple linear regression analyses revealed that strong VEGFR-2 expression was positively associated with the best reduction in tumor response (β = -0.275, P = 0.016) and poor Karnofsky performance status was negatively associated it (β = 0.477, P < 0.001). Karnofsky performance status and retroperitoneal lymph node involvement associated independently with progression-free- and overall survivals. None of the molecular markers associated significantly with survival. VEGFR-2 expression might be a useful biomarker for predicting the response to sunitinib by patients with metastatic RCC. Karnofsky performance status and retroperitoneal lymph node involvement were predictive of disease progression and death.

Reduced Mural Cell Coverage and Impaired Vessel Integrity After Angiogenic Stimulation in the Alk1 -deficient Brain

Vessels in brain arteriovenous malformations are prone to rupture. The underlying pathogenesis is not clear. Hereditary hemorrhagic telangiectasia type 2 patients with activin receptor-like kinase 1 (Alk1) mutation have a higher incidence of brain arteriovenous malformation than the general population. We tested the hypothesis that vascular endothelial growth factor impairs vascular integrity in the Alk1-deficient brain through reduction of mural cell coverage. Adult Alk1(1f/2f) mice (loxP sites flanking exons 4-6) and wild-type mice were injected with 2×10(7) PFU adenovious-cre recombinase and 2×10(9) genome copies of adeno-associated virus-vascular endothelial growth factor to induce focal homozygous Alk1 deletion (in Alk1(1f/2f) mice) and angiogenesis. Brain vessels were analyzed 8 weeks later. Compared with wild-type mice, the Alk1-deficient brain had more fibrin (99±30×10(3) pixels/mm(2) versus 40±13×10(3); P=0.001), iron deposition (508±506 pixels/mm(2) versus 6±49; P=0.04), and Iba1(+) microglia/macrophage infiltration (888±420 Iba1(+) cells/mm(2) versus 240±104 Iba1(+); P=0.001) after vascular endothelial growth factor stimulation. In the angiogenic foci, the Alk1-deficient brain had more α-smooth muscle actin negative vessels (52±9% versus 12±7%, P<0.001), fewer vascular-associated pericytes (503±179/mm(2) versus 931±115, P<0.001), and reduced platelet-derived growth factor receptor-β expression. Reduction of mural cell coverage in response to vascular endothelial growth factor stimulation is a potential mechanism for the impairment of vessel wall integrity in hereditary hemorrhagic telangiectasia type 2-associated brain arteriovenous malformation.

Notch Signaling Regulates Platelet-Derived Growth Factor Receptor-β Expression in Vascular Smooth Muscle Cells

Notch signaling is critically important for proper architecture of the vascular system, and mutations in NOTCH3 are associated with CADASIL, a stroke and dementia syndrome with vascular smooth muscle cell (VSMC) dysfunction. In this report, we link Notch signaling to platelet-derived growth factor (PDGF) signaling, a key determinant of VSMC biology, and show that PDGF receptor (PDGFR)-beta is a novel immediate Notch target gene. PDGFR-beta expression was upregulated by Notch ligand induction or by activated forms of the Notch receptor. Moreover, upregulation of PDGFR-beta expression in response to Notch activation critically required the Notch signal integrator CSL. In primary VSMCs, PDGFR-beta expression was robustly upregulated by Notch signaling, leading to an augmented intracellular response to PDGF stimulation. In newborn Notch3-deficient mice, PDGFR-beta expression was strongly reduced in the VSMCs that later develop an aberrant morphology. In keeping with this, PDGFR-beta upregulation in response to Notch activation was reduced also in Notch3-deficient embryonic stem cells. Finally, in VSMCs from a CADASIL patient carrying a NOTCH3 missense mutation, upregulation of PDGFR-beta mRNA and protein in response to ligand-induced Notch activation was significantly reduced. In sum, these data reveal a hierarchy for 2 important signaling systems, Notch and PDGF, in the vasculature and provide insights into how dysregulated Notch signaling perturbs VSMC differentiation and function.

Chimera Analysis Reveals That Fibroblasts and Endothelial Cells Require Platelet-Derived Growth Factor Receptorβ Expression for Participation in Reactive Connective Tissue Formation in Adults but Not during Development

The hypothesis that platelet-derived growth factor (PDGF) plays an important role in repair of connective tissue has been difficult to test experimentally, in part because the disruption of any of the PDGF ligand and receptor genes is embryonic lethal. We have developed a method that circumvents the embryonic lethality of the PDGF receptor (R)beta-/- genotype and minimizes the tendency of compensatory processes to mask the phenotype of gene disruption by comparing the behavior of wild-type and PDGFRbeta-/- cells within individual chimeric mice. This quantitative chimera analysis method has revealed that during development PDGFRbeta expression is important for all muscle lineages but not for fibroblast or endothelial lineages. Here we report that fibroblasts and endothelial cells, but not leukocytes, are dependent on PDGFRbeta expression during the formation of new connective tissue in and around sponges implanted under the skin. Even the 50% reduction in PDGFRbeta gene dosage in PDGFRbeta+/- cells reduces fibroblast and endothelial cell participation by 85%. These results demonstrate that the PDGFRbeta/PDGF B-chain system plays an important direct role in driving both fibroblast and endothelial cell participation in connective tissue repair, that cell behavior can be regulated by relatively small changes in PDGFRbeta expression, and that the functions served by PDGF in wound healing are different from the roles served during development.