Platelet-derived Growth Factor Receptor Inhibitor Research Articles

BASELINE CHARACTERISTICS OF ALL PATIENTS ENROLLED IN A PHASE II CLINICAL TRIAL ASSESSING THE EFFICACY AND SAFETY OF NINTEDANIB IN LYMPHANGIOLEIOMYOMATOSIS

TYPE: Abstract Publication TOPIC: Diffuse Lung Disease PURPOSE: Lymphangioleiomyomatosis (LAM) is a disease, mainly affecting women. It can be sporadic or associated to Tuberous Sclerosis (TSC). In the MILES trial, sirolimus, has been proven to be effective in the treatment of patients with LAM. Drug toxicity and resistance are problems related to sirolimus. Nintedanib is an inhibitor of the tyrosin kinase PDGF receptor (PDGFR) present and active in human and murine TSC lesions. The aim of this abstract is to report the baseline characteristics of all LAM patients enrolled in this trial investigating the efficacy and safety of nintedanib METHODS: 30 LAM patients showing a progressive pulmonary function decline in the last year or side effects and/or toxicities/contraindications to sirolimus. The protocol planned 12 months of treatmentwith nintedanib fand 12 month of follow up without treatment. The primary endpoint is the FEV1 response . RESULTS: Baseline characteristics of the pts are reported below and compared with those from the MILES trial. CONCLUSIONS: The results of this ongoing study will allow assessment of the impact of nintedanib in LAM patients CLINICAL IMPLICATIONS: DISCLOSURE: No significant relationships. KEYWORD: lymphangioleiomYomatosis; cistic lung disease

3D in vitro Model of Vascular Medial Thickening in Pulmonary Arterial Hypertension.

In pulmonary arterial hypertension (PAH), excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) causes vascular medial thickening. Medial thickening is a histopathological hallmark of pulmonary vascular remodeling, the central disease process driving PAH progression. Pulmonary vascular remodeling causes stenosis and/or obstruction of small pulmonary arteries. This leads to increased pulmonary vascular resistance, elevated pulmonary arterial pressure, and ultimately right heart failure. To improve the survival of PAH patients, which remains at approximately 60% at 3 years after diagnosis, the development of novel PAH-targeted drugs is desired. To this end, a detailed understanding of the mechanisms underlying excessive PASMC proliferation and the medial thickening that ensues is necessary. However, a lack of in vitro models that recapitulate medial thickening impedes our deeper understanding of the pathogenetic mechanisms involved. In the present study, we applied 3-dimensional (3D) cell culture technology to develop a novel in vitro model of the pulmonary artery medial layer using human PAH patient-derived PASMCs. The addition of platelet-derived growth factor (PDGF)-BB, a mitogen known to promote excessive PASMC proliferation in PAH, resulted in increased thickness of the 3D-PAH media tissues. Conversely, administration of the PDGF receptor inhibitor imatinib or other clinical PAH drugs inhibited this medial thickening-inducing effect of PDGF-BB. Altogether, by using 3D cell culture technology, we report the generation of an in vitro model of medial thickening in PAH, which had hitherto not been successfully modeled in vitro. This model is potentially useful for assessing the ability of candidate PAH drugs to suppress medial thickening.

Imatinib Sets Pericyte Mosaic in the Retina.

The nervous system demands an adequate oxygen and metabolite exchange, making pericytes (PCs), the only vasoactive cells on the capillaries, essential to neural function. Loss of PCs is a hallmark of multiple diseases, including diabetes, Alzheimer’s, amyotrophic lateral sclerosis (ALS) and Parkinson’s. Platelet-derived growth factor receptors (PDGFRs) have been shown to be critical to PC function and survival. However, how PDGFR-mediated PC activity affects vascular homeostasis is not fully understood. Here, we tested the hypothesis that imatinib, a chemotherapeutic agent and a potent PDGFR inhibitor, alters PC distribution and thus induces vascular atrophy. We performed a morphometric analysis of the vascular elements in sham control and imatinib-treated NG2-DsRed mice. Vascular morphology and the integrity of the blood–retina barrier (BRB) were evaluated using blood albumin labeling. We found that imatinib decreased the number of PCs and blood vessel (BV) coverage in all retinal vascular layers; this was accompanied by a shrinkage of BV diameters. Surprisingly, the total length of capillaries was not altered, suggesting a preferential effect of imatinib on PCs. Furthermore, blood–retina barrier disruption was not evident. In conclusion, our data suggest that imatinib could help in treating neurovascular diseases and serve as a model for PC loss, without BRB disruption.

S2P peptide-conjugated PLGA-Maleimide-PEG nanoparticles containing Imatinib for targeting drug delivery to atherosclerotic plaques.

Imatinib is a platelet-derived growth factor receptor (PDGFR) inhibitor with very low water solubility. Previous studies in atherosclerosis have shown that PDGFR activity has an egregious effect on vascular disease and progression of atherosclerosis. Specific ligands of atherosclerotic plaques can be used for targeting of nanoparticles. Studies in atherosclerosis proved that stabilin-2 is a glycoprotein which exists abundantly in atherosclerotic plaques and it is produced from both macrophages and endothelial cells. The objective of this study is the targeting drug delivery to atherosclerotic plaques by using imatinib-loaded nanoparticles modified by S2P peptide. The imatinib-loaded nanoparticles were fabricated through a modified emulsion/solvent evaporation technique. After fabricating PLGA nanoparticles, maleimide PEG was used as linker between PLGA nanoparticles and S2P peptide. Because of presence cysteine in both side of S2P peptide, maleimide formed a thiolether linkage by thiol group of cysteine. Then the physicochemical analysis like H-NMR, FT-IR, DSC, SEM, particle size, zeta potential, and drug release were studied. Stabilin-2 peptide with sequence of CRTLTVRKC is a specific ligand to stabilin-2, so it was synthesized for using as the targeting agent for atherosclerosis. S2P peptide conjugation to the surface of nanoparticles was proved by H-NMR and FT-IR, and the percentage of S2P peptide in nanoparticles was 1.3%. The final nanoparticles were spherical and their size were 183nm. The loading capacity of the imatinib-loaded nanoparticles was 5.05%. The sustained release profile was observed for peptide targeted nanoparticles. The chosen method was simple, reproducible, and specific in peptide conjugation of nanoparticles for targeting delivery to atherosclerotic regions. Graphical abstract .

Exploring the interaction between tyrphostin 9 and human serum albumin using biophysical and computational methods

Tyrphostin 9 (Tyr 9) is a potent platelet-derived growth factor receptor (PDGFR) inhibitor, which induces apoptosis in various cancer cell types. The binding of Tyr 9 to the major transport protein, human serum albumin (HSA) was investigated using several spectroscopic techniques and molecular docking method. Fluorescence quenching titration results showed progressive decrease in the protein fluorescence with increasing drug concentrations. A decreasing trend of the Stern-Volmer constant, K sv with increasing temperature characterized the drug-induced quenching as static quenching, thus pointed towards the formation of Tyr 9–HSA complex. The binding constant of Tyr 9–HSA interaction was found to lie within the range 3.48–1.69 × 105 M−1 at three different temperatures, i.e. 15 °C, 25 °C and 35 °C, respectively and suggested intermediate binding affinity between Tyr 9 and HSA. The drug–HSA complex seems to be stabilized by hydrophobic forces, van der Waals forces and hydrogen bonds, as suggested from the thermodynamic data as well as molecular docking results. The far-UV and the near-UV CD spectral results showed slight alteration in the secondary and tertiary structures, respectively, of the protein upon Tyr 9 binding. Interaction of Tyr 9 with HSA also produced microenvironmental perturbations around protein fluorophores, as evident from the three-dimensional fluorescence spectral results but increased protein’s thermal stability. Both competitive drug binding results and molecular docking analysis suggested Sudlow’s Site I of HSA as the preferred Tyr 9 binding site. Communicated by Ramaswamy H. Sarma

Severe Ulcerative Skin Lesions Due to Lenvatinib

Lenvatinib is an antiangiogenic tyrosine kinase inhibitor that effectively treats advanced hepatocellular carcinoma. However, lenvatinib has several side effects, including hand-foot skin reactions. A 70-year-old female patient with hepatocellular carcinoma measuring 9 cm in diameter was referred to our hospital. Her liver function showed Child-Pugh grade A, and lenvatinib was started (8 mg daily). After 4 weeks, both of her hands and feet showed several blisters and necrotic lesions. Lenvatinib was temporarily discontinued. Four weeks later, her syndrome improved, and lenvatinib was reinstituted at 4 mg daily. Painful hand-foot syndrome reemerged during the next three weeks and simultaneously, an ulcerative left thigh skin lesion occurred (Figure A and B). Lenvatinib was discontinued, and prostaglandin ointments were administered. Four weeks later, her hand-foot syndrome and ulcerative skin lesion disappeared (Figure C and D). Painful skin lesions as an adverse effect of lenvatinib usually present on keratinized areas of the palms and soles. The precise mechanism by which lenvatinib causes hand-foot syndrome is not understood, but impairment in repair via platelet-derived growth factor receptor inhibition may play a role. The skin lesion side effect of lenvatinib can occur in keratinized areas of palms and soles and in soft skin tissues across the whole body.

The Tyrosine Kinase Inhibitor TAS-115 Attenuates Bleomycin-induced Lung Fibrosis in Mice.

The signaling pathways of growth factors, including platelet-derived growth factor, can be considered specific targets for overcoming the poor prognosis of idiopathic pulmonary fibrosis. Nintedanib, the recently approved multiple kinase inhibitor, has shown promising antifibrotic effects in patients with idiopathic pulmonary fibrosis; however, its efficacy is still limited, and in some cases, treatment discontinuation is necessary owing to toxicities such as gastrointestinal disorders. Therefore, more effective agents with less toxicity are still needed. TAS-115 is a novel multiple tyrosine kinase inhibitor that preferably targets platelet-derived growth factor receptor (PDGFR), vascular endothelial growth factor receptor, and c-FMS in addition to other molecules. In this study, we evaluated the antifibrotic effect of TAS-115 on pulmonary fibrosis in vitro and in vivo. TAS-115 inhibited the phosphorylation of PDGFR on human lung fibroblast cell line MRC-5 cells and suppressed their platelet-derived growth factor-induced proliferation and migration. Furthermore, TAS-115 inhibited the phosphorylation of c-FMS, a receptor of macrophage colony-stimulating factor, in murine bone marrow-derived macrophages and decreased the production of CCL2, another key molecule for inducing pulmonary fibrosis, under the stimulation of macrophage colony-stimulating factor. Importantly, the inhibitory effects of TAS-115 on both PDGFR and c-FMS were 3- to 10-fold higher than those of nintedanib. In a mouse model of bleomycin-induced pulmonary fibrosis, TAS-115 significantly inhibited the development of pulmonary fibrosis and the collagen deposition in bleomycin-treated lungs. These data suggest that strong inhibition of PDGFR and c-FMS by TAS-115 may be a promising strategy for overcoming the intractable pathogenesis of pulmonary fibrosis.

Phase II trial of nintedanib in patients with bevacizumab-resistant recurrent epithelial ovarian, tubal, and peritoneal cancer

BackgroundBevacizumab provides benefit in epithelial ovarian cancer (EOC), yet resistance to bevacizumab often occurs. We determined if nintedanib, a tyrosine kinase inhibitor of VEGF, FGF, and PDGF receptors has antitumor activity in bevacizumab-resistant recurrent EOC, tubal, and peritoneal cancer. MethodsThis phase II study evaluated nintedanib 200 mg/day until disease progression or unacceptable toxicity. The primary objective was 6-month progression free survival (PFS6m). Secondary objectives were response rate and toxicity. Simon two-stage optimal design was used. Baseline angiogenic plasma biomarkers were measured. Results27 patients were enrolled evaluable for PFS; 26 were evaluable for PFS6m. The median age was 65 years (range 44–73); 89.9% had high-grade serous EOC; 70% received at least >2 prior chemotherapies; and 81% (22/27) had chemoresistant disease. With median follow up of 15.6 months (range 2–38) the PFS6m rate was 11.5% (3/26). Three participants had long duration of disease control (8–16 months). Median PFS and overall survival were 1.8 and 16 months, respectively. Response rate was 7.4% (2/27 PR). Thirty-seven percent (10/27) had stable disease, while 56% (15/27) had progressive disease. Adverse events included Grade 3 liver enzyme elevation (15%), Grade 3 diarrhea (7%), Grade 2 fatigue (7%), and Grade 2 nausea/vomiting (15%). PD patients exhibited higher levels of CD73, IL6, and VEGFD (p < 0.05) compared to PR/SD patients. IL6 was associated with worse PFS (p = 0.03). ConclusionsSingle-agent nintedanib has minimal activity in an unselected bevacizumab-resistant EOC population. Nintedanib was tolerable and toxicities were manageable. Plasma CD73, IL6, and VEGFD were identified as prognostic markers for progressive disease, and IL6 was associated with worse PFS confirming similar observations made in patients treated with other anti-angiogenic agents.

Basic Fibroblast Growth Factor Induces Adipogenesis in Orbital Fibroblasts: Implications for the Pathogenesis of Graves' Orbitopathy.

Basic fibroblast growth factor (bFGF) has been implicated in the pathogenesis of Graves' orbitopathy (GO). It stimulates several processes, including hyaluronan synthesis, involved in orbital tissue volume expansion and may act synergistically with platelet-derived growth factor (PDGF)-BB. PDGF-BB is known to stimulate adipogenesis in orbital fibroblasts, but the effect of bFGF on adipogenesis in orbital fibroblasts is so far unknown. This study was conducted to determine whether (i) bFGF induces adipogenesis in orbital fibroblasts, (ii) bFGF and PDGF-BB together exert an additive or synergistic effect on adipogenesis, and (iii) treatment directed at bFGF- and PDGF-BB signaling may potentially be of interest for the treatment of GO. Orbital fibroblasts from GO patients and controls were cultured in adipocyte differentiation medium with or without bFGF and/or PDGF-BB at different concentrations. Adipogenesis was determined by Oil Red O staining and messenger RNA expression of the late adipocyte differentiation markers cell death-inducing DFFA-like effector C (CIDEC) and adiponectin (ADIPOQ). To demonstrate involvement of FGF-receptor and PDGF-receptor signaling, experiments were also conducted in the presence of dasatinib (inhibitor of PDGF-receptor) or nintedanib (inhibitor of PDGF-receptor and FGF-receptor). bFGF significantly stimulated adipogenesis by orbital fibroblasts, as shown by increased Oil Red O staining and CIDEC and ADIPOQ expression after 14 days of differentiation. Furthermore, an additive effect of bFGF/PDGF-BB co-stimulation on adipogenesis was observed at the lowest concentration (12.5 ng/mL) of the growth factors tested. Nintedanib completely inhibited bFGF-, PDGF-BB-, and bFGF/PDGF-BB-induced adipogenesis, while dasatinib only fully abrogated PDGF-BB-induced adipogenesis. bFGF induces adipogenesis in orbital fibroblasts and as such may contribute to GO. The additive effect of bFGF and PDGF-BB on adipogenesis, along with the observed inhibitory effects of dasatinib and nintedanib, point at independent receptor-mediated effects. This supports the hypothesis that multi-target directed therapy might be more efficient in the treatment of GO.

CXCL17-derived CD11b+Gr-1+ myeloid-derived suppressor cells contribute to lung metastasis of breast cancer through platelet-derived growth factor-BB

BackgroundMetastasis is the major cause of death from breast cancer. Colonization and adaption of metastatic cells in distant organs is a rate-limiting step of the cancer spreading. The underlying mechanisms responsible for the colonization of breast cancer to lung metastatic niches are not fully understood.MethodsSpecific gene contributions to lung metastasis were identified by comparing gene profiles of 4T1 tumors metastasizing to various organs via microarray. The oncogenic properties CXCL17 were examined by in vivo spontaneous metastasis mouse model. The chemotactic activity of CXCL17 on CD11b+Gr-1+ myeloid-derived suppressor cells (MDSCs) was examined by both in vitro and in vivo models. The therapeutic effects of MDSC depletion and platelet-derived growth factor-BB (PDGF-BB) inhibition were examined by orthotic models.ResultsHere, we demonstrate that breast cancer cells secrete CXCL17, which increases the accumulation of CD11b+Gr-1+ MDSCs in the lungs. Metastatic lung-infiltrating CD11b+Gr-1+ MDSCs induce angiogenesis in the lungs and facilitate cancer extravasation and survival that ultimately promote lung metastases. CXCL17 increases CD11b+Gr-1+ MDSCs to express PDGF-BB, which not only contributes to CD11b+Gr-1+ MDSC-mediated angiogenesis in the lung metastatic niche, but is also involved in the colonization of breast cancer. Consequently, both CD11b+Gr-1+ MDSC depletion and PDGF receptor inhibitor effectively prevents CXCL17-driven lung metastasis in breast cancer. More importantly, patients with high levels of CXCL17 have shorter distant metastasis-free and overall survival rates, indicators of poor prognosis.ConclusionOur study reveals that MDSCs derived by CXCL17 contribute to the establishment of a lung metastatic niche by PDGF-BB secretion and provide a rationale for development of CXCL17 or PDGF-BB antagonists to inhibit or prevent lung metastasis in cases of breast cancer.

Multikinase inhibitor motesanib enhances the antitumor effect of cisplatin in cisplatin‑resistant human bladder cancer cells via apoptosis and the PI3K/Akt pathway.

Motesanib (AMG 706) is a small organic molecule that acts as a multi‑targeted tyrosine kinase inhibitor of VEGF, PDGF and stem cell factor receptor. It exhibits a potent antitumor effect in vitro and in vivo. To investigate the anticancer effect and possible mechanisms of motesanib in cisplatin‑resistant human bladder cancer cells (T24R2), T24R2 cells were treated with motesanib (50 µM) with or without cisplatin (2.5 µg/ml). Cell growth was assessed by the Cell Counting Kit‑8 and clonogenic assays. Cell cycle progression and apoptotic cell death were examined using flow cytometry. The expression levels of apoptosis‑ and survival‑related proteins were determined by western blot analysis. In combination with cisplatin, motesanib exhibited synergistic inhibition on T24R2 cell growth. Treatment using motesanib in combination with cisplatin markedly induced apoptosis and promoted cell cycle arrest in the S phase. It also increased the expression of apoptosis‑related genes including caspases, poly(ADP‑ribose) polymerase and cytochrome c, whereas it decreased the expression of survival‑related genes including p‑PI3K and p‑Akt. In conclusion, combination treatment with motesanib and cisplatin revealed a synergistically enhanced anticancer effect on cisplatin‑resistant human bladder cancer cells, accompanied with induced apoptosis and cell cycle arrest. Thus, the multikinase inhibitor motesanib could be developed as possible therapeutic agent for bladder cancer.

Impaired adrenergic agonist-dependent beige adipocyte induction in obese mice.

Brown adipocytes, which exist in brown adipose tissue (BAT), are activated by adrenergic stimulation, depending on the activity of uncoupling protein 1 (UCP1). Beige adipocytes emerge from white adipose tissue (WAT) in response to chronic adrenergic stimulation. We investigated obesity-related changes in responses of both types of adipocytes to adrenergic stimulation in mice. Feeding of mice with high-fat diets (HFD: 45%-kcal fat) for 14 weeks resulted in significantly higher body and WAT weight compared to feeding with normal diets (ND: 10%-kcal fat). Injection with β3-adrenergic receptor agonist CL316,243 (CL; 0.1 mg/kg, once a day) for one week elevated the mRNA and protein expression levels of UCP1 in BAT, irrespective of diet. In WAT, CL-induced UCP1 expression in ND mice; however, the responses to CL treatment were attenuated in HFD mice, indicating that CL-induced browning of WAT was impaired in obese mice. Flow cytometric analysis revealed a significant decrease in platelet-derived growth factor receptor (PDGFR) α-expressing beige adipocyte progenitors in WAT of HFD mice compared with those of ND mice. Expression of PDGF-B, a PDGFRα ligand, increased in WAT following CL-injection in ND mice, but not in HFD mice. Treatment of mice with a PDGFR inhibitor significantly decreased CL-dependent UCP1 protein induction in WAT. Our study demonstrates that β3-adrenergic stimulation-dependent beige adipocyte induction in WAT is impaired by obesity in mice, potentially due to obesity-dependent reduction in the number of PDGFRα-expressing progenitors and decreased PDGF-B expression.

Pathogenic Role of mTORC1 and mTORC2 in Pulmonary Hypertension

Concentric lung vascular wall thickening due to enhanced proliferation of pulmonary arterial smooth muscle cells is an important pathological cause for the elevated pulmonary vascular resistance reported in patients with pulmonary arterial hypertension. We identified a differential role of mammalian target of rapamycin (mTOR) complex 1 and complex 2, two functionally distinct mTOR complexes, in the development of pulmonary hypertension (PH). Inhibition of mTOR complex 1 attenuated the development of PH; however, inhibition of mTOR complex 2 caused spontaneous PH, potentially due to up-regulation of platelet-derived growth factor receptors in pulmonary arterial smooth muscle cells, and compromised the therapeutic effect of the mTOR inhibitors on PH. In addition, we describe a promising therapeutic strategy using combination treatment with the mTOR inhibitors and the platelet-derived growth factor receptor inhibitors on PH and right ventricular hypertrophy. The data from this study provide an important mechanism-based perspective for developing novel therapies for patients with pulmonary arterial hypertension and right heart failure.

Beneficial effects of sunitinib on tumor microenvironment and immunotherapy targeting death receptor5

ABSTRACTTumor-associated blood vessels and lymphatics are abnormal and dysfunctional. These are hallmarks of the tumor microenvironment, which has an immunosuppressive nature, such as through hypoxia. Treatment with anti-death receptor5 (DR5) monoclonal antibody MD5-1, which induces tumor cell death, is a potent anti-tumor immunotherapy. Generally, MD5-1 induces cell death mainly via antigen presenting cells (APCs) and generates tumor-specific effector T cells. To date, the effects of a simultaneous functional improvement of abnormal blood vessels and lymphatics on the immune microenvironment are largely unknown. A combination therapy using sunitinib, vascular endothelial growth factor (VEGF) and platelet-derived growth factor receptor inhibitor, and MD5-1 substantially inhibited tumor growth. Sunitinib improved pericyte coverage on endothelial cells and the expression levels of regulator of G-protein signaling 5, suggesting blood vessel normalization. Sunitinib also increased lymph flow from tumors to central lymph nodes, suggesting improved lymphatic function. In concordance with improved vasculature functions, sunitinib alleviated the tumor hypoxia, suggesting an improved tumor microenvironment. Indeed, the combination therapy induced strong activation of CD8+ T cells and dendritic cells in draining lymph nodes. The combination therapy reduced the ratio of immune-suppressive T regulatory cells in the tumors and draining lymph nodes. The combination therapy enhanced the numbers and activation of tumor-infiltrating CD8+ T cells. CD4 and/or CD8 depletion, or APC inhibiting experiments showed the contribution of CD8+ T cells and APCs to the combination therapy. These findings suggest that targeting blood vessels and lymphatics may have potential benefits for immunotherapy mediated by CD8+ T cells and APCs.

Factors Secreted by Cancer-Associated Fibroblasts that Sustain Cancer Stem Properties in Head and Neck Squamous Carcinoma Cells as Potential Therapeutic Targets.

This study investigates for the first time the crosstalk between stromal fibroblasts and cancer stem cell (CSC) biology in head and neck squamous cell carcinomas (HNSCC), with the ultimate goal of identifying effective therapeutic targets. The effects of conditioned media from cancer-associated fibroblasts (CAFs) and normal fibroblasts (NFs) on the CSC phenotype were assessed by combining functional and expression analyses in HNSCC-derived cell lines. Further characterization of CAFs and NFs secretomes by mass spectrometry was followed by pharmacologic target inhibition. We demonstrate that factors secreted by CAFs but not NFs, in the absence of serum/supplements, robustly increased anchorage-independent growth, tumorsphere formation, and CSC-marker expression. Modulators of epidermal growth factor receptor (EGFR), insulin-like growth factor receptor (IGFR), and platelet-derived growth factor receptor (PDGFR) activity were identified as paracrine cytokines/factors differentially secreted between CAFs and NFs, in a mass spectrometry analysis. Furthermore, pharmacologic inhibition of EGFR, IGFR, and PDGFR significantly reduced CAF-induced tumorsphere formation and anchorage-independent growth suggesting a role of these receptor tyrosine kinases in sustaining the CSC phenotype. These findings provide novel insights into tumor stroma–CSC communication, and potential therapeutic targets to effectively block the CAF-enhanced CSC niche signaling circuit.

A small molecule fibrokinase inhibitor in a model of fibropolycystic hepatorenal disease.

AIMTo evaluate the novel platelet-derived growth factor receptor and vascular endothelial growth factor receptor dual kinase inhibitor ANG3070 in a polycystic kidney disease-congenital hepatic fibrosis model.METHODSAt 6 wk of age, PCK rats were randomized to vehicle or ANG3070 for 4 wk. At 10 wk, 24 h urine and left kidneys were collected and rats were continued on treatment for 4 wk. At 14 wk, 24 h urine was collected, rats were sacrificed, and liver and right kidneys were collected for histological evaluation. For Western blot studies, PCK rats were treated with vehicle or ANG3070 for 7 d and sacrificed approximately 30 min after the last treatments.RESULTSCompared to the wild-type cohort, the PCK kidney (Vehicle cohort) exhibited a marked increase in kidney and liver mass, hepato-renal cystic volume, hepato-renal fibrosis and hepato-renal injury biomarkers. Intervention with ANG3070 in PCK rats decreased kidney weight, reduced renal cystic volume and reduced total kidney hydroxyproline, indicating significantly reduced rental interstitial fibrosis compared to the PCK-Vehicle cohort. ANG3070 treatment also mitigated several markers of kidney injury, including urinary neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, cystatin C and interleukin-18 levels. In addition, this treatment attenuated key indices of renal dysfunction, including proteinuria, albuminuria and serum blood urea nitrogen and creatinine, and significantly improved renal function compared to the PCK-Vehicle cohort. ANG3070 treatment also significantly decreased liver enlargement, hepatic lesions, and liver fibrosis, and mitigated liver dysfunction compared to the PCK-Vehicle cohort.CONCLUSIONThese results suggest that ANG3070 has the potential to slow disease, and may serve as a bridge toward hepato-renal transplantation in patients with fibropolycystic disease.

Abstract P127: Pericyte Detachment is Involved in Renal Congestion in a Novel Rat Model

Increased central venous pressure in congestive heart failure is responsible for renal dysfunction; however, the underlying mechanisms are unclear. We hypothesized that renal interstitial hydrostatic pressure (RIHP) and expansion pressures of the vasa recta are responsible for pericyte detachment resulting renal congestion-mediated fibrosis. We created a novel rat renal congestion model and investigated the effect of renal congestion on hemodynamics and its molecular mechanisms. The inferior vena cava (IVC) between the renal veins was ligated by suture in male Sprague-Dawley rats to increase upstream IVC pressure and induce congestion in the left kidney only. Left kidney congestion reduced renal blood flow in cortex (33.6%, 28.3 to 16.0 mL/min) and in medulla (41.8%, 11.9 to 6.9 mL/min) and glomerular filtration rate (1.16 to 0.20 mL/min/kg BW), and increased RIHP (12.6 to 17.6 mm Hg). Hypoxia was observed in the medullary thick ascending limb of Henle, only in the congestive kidneys. Tubulointerstitial injury, podocyte injury, albuminuria, and reduced creatinine clearance were observed in the congestive kidneys. Molecules related to extracellular matrix expansion, tubular injury, and focal adhesion were upregulated in microarray analysis. Renal decapsulation ameliorated the tubulointerstitial injury (mRNA expression of Kim1 15.3 to 4.3 A.U., αSma 5.3 to 2.8 A.U.). Electron microscopy captured pericyte detachment in the congestive kidneys. Transgelin and platelet-derived growth factor receptors (PDGFRs), as indicators of pericyte-myofibroblast transition, were upregulated in the pericytes and the adjacent interstitium. Imatinib, a PDGFR inhibitor, ameliorated the interstitial injury. Our results reveal a novel mechanism of worsening renal function associated with congestive heart failure, and provide a new therapeutic strategy based on a better understanding of the pericyte-myofibroblast transition.

COP9 signalosome subunit 6 mediates PDGF -induced pulmonary arterial smooth muscle cells proliferation

Up-regulation of mammalian COP9 signalosome subunit 6 (CSN6) and consequent reduction of SCF ubiquitin ligase substrate receptor β-transduction repeat-containing protein (β-TrCP) have been shown to be associated with cancer cells proliferation. However, it is unclear whether CSN6 and β-TrCP are also involved in PDGF-induced pulmonary arterial smooth muscle cells (PASMCs) proliferation. This study aims to address this issue and further explore its potential mechanisms. Our results indicated that PDGF phosphorylated Akt, stimulated PASMCs proliferation; while inhibition of PDGF receptor (PDGFR) by imatinib prevented these effects. PDGF further up-regulated CSN6 protein expression, this was accompanied with β-TrCP reduction and increase of Cdc25A. Inhibition of PDGFR/PI3K/Akt signaling pathway reversed PDGF-induced such changes and cell proliferation. Prior transfection of CSN6 siRNA blocked PDGF-induced β-TrCP down-regulation, Cdc25A up-regulation and cell proliferation. Furthermore, pre-treatment of cells with MG-132 also abolished PDGF-induced β-TrCP reduction, Cdc25A elevation and cell proliferation. In addition, pre-depletion of Cdc25A by siRNA transfection suppressed PDGF-induced PASMCs proliferation. Taken together, our study indicates that up-regulation of CSN6 by PDGFR/PI3K/Akt signaling pathway decreases β-TrCP by increasing its ubiquitinated degradation, and thereby increases the expression of Cdc25A, which promotes PDGF-induced PASMCs proliferation.

Glucose-regulated protein 78 in lipid rafts elevates vascular smooth muscle cell proliferation of spontaneously hypertensive rats by controlling platelet-derived growth factor receptor signaling.

The multifunctional glucose-regulated protein 78 (GRP78) is known to be differentially expressed in the lipid rafts of vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHRs) and normal Wistar-Kyoto (WKY) rats. However, its role in VSMCs from SHRs remains to be elucidated. This work was conducted to investigate the contribution made by GRP78 in VSMCs. GRP78 expression in VSMC lipid rafts decreased in WKY rats with age, but not in SHRs. Transfection with GRP78-siRNA attenuated not only platelet-derived growth factor (PDGF)-BB-induced VSMC proliferation and aortic sprout outgrowth but also the phosphorylation of PDGF receptor (PDGFR)-β, Akt, and extracellular signal-regulated kinase (Erk) 1/2 in VSMCs in response to PDGF-BB. Moreover, GRP78 knockdown also reduced the PDGF-BB-induced dimerization of PDGFR-β and GRP78 in SHR VSMCs. The phosphorylation of GRP78 and PDGFR-β was elevated in VSMCs treated with PDGF-BB and was completely abolished by AG1296 (a PDGFR inhibitor). Moreover, the binding of PDGFR-β to GRP78 and the co-localization of GRP78 to PDGFR-β in VSMCs were stronger in SHRs than in WKY rat controls. This study demonstrates that the PDGF-BB-induced proliferation of SHR VSMCs is mediated by the expressional upregulation of GRP78 on VSMC lipid rafts in SHRs, probably via the regulation of PDGFR-β-GRP78 binding and their cross-activation. These observations indicate that GRP78 may play important roles in the pathological progression of SHR VSMCs.

Quantitative Proteomics of TRAMP Mice Combined with Bioinformatics Analysis Reveals That PDGF-B Regulatory Network Plays a Key Role in Prostate Cancer Progression.

Transgenic adenocarcinoma of the mouse prostate (TRAMP) mice is a widely used transgenic animal model of prostate cancer (PCa). We performed a label-free quantitative proteomics analysis combined with a bioinformatics analysis on the entire prostate protein extraction from TRAMP mice and compared it with WT littermates. From 2379 total identified proteins, we presented a modest mice prostate reference proteome containing 919 proteins. 61 proteins presented a significant expression difference between two groups. The integrative bioinformatics analysis predicted the overexpression of platelet-derived growth factor B (PDGF-B) in tumor tissues and supports the hypothesis of the PDGF-B signaling network as a key upstream regulator in PCa progression. Furthermore, we demonstrated that Crenolanib, a novel PDGF receptor inhibitor, inhibited PCa cell proliferation in a dose-dependent manner. Finally, we revealed the importance of PDGF-B regulatory network in PCa progression, which will assist us in understanding the role and mechanisms of PDGF-B in promoting cancer growth and provide valuable knowledge for future research on anti-PDGF therapy.