Phase II Study of Dovitinib in Patients with Castration-Resistant Prostate Cancer (KCSG-GU11-05) / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Fibroblast growth factor (FGF) signals are important in carcinogenesis and progression of prostate cancer. Dovitinib is an oral, pan-class inhibitor of vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor, and fibroblast growth factor receptor (FGFR). We evaluated the efficacy and toxicity of dovitinib in men with metastatic castration resistant prostate cancer (mCRPC). MATERIALS AND METHODS: This study was a single-arm, phase II, open-label, multicenter trial of dovitinib 500 mg/day (5-days-on/2-days-off schedule). The primary endpoint was 16-week progression-free survival (PFS). Secondary endpoints were overall survival (OS), toxicity and prostate-specific antigen (PSA) response rate. Biomarker analyses for VEGFR2, FGF23, and FGFR2 using multiplex enzyme-linked immunosorbent assay was performed. RESULTS: Forty-four men were accrued from 11 hospitals. Eighty percent were post-docetaxel. Median PSA was 100 ng/dL, median age was 69, 82% had bone metastases, and 23% had liver metastases. Median cycles of dovitinib was 2 (range, 0 to 33). Median PFS was 3.67 months (95% confidence interval [CI], 1.36 to 5.98) and median OS was 13.70 months (95% CI, 0 to 27.41). Chemotherapy-naïve patients had longer PFS (17.90 months; 95% CI, 9.23 to 28.57) compared with docetaxel-treated patients (2.07 months; 95% CI, 1.73 to 2.41; p=0.001) and the patients with high serum VEGFR2 level over median level (7,800 pg/mL) showed longer PFS compared with others (6.03 months [95% CI, 4.26 to 7.80] vs. 1.97 months [95% CI, 1.79 to 2.15], p=0.023). Grade 3 related adverse events were seen in 40.9% of patients. Grade 1-2 nausea, diarrhea, fatigue, anorexia, and all grade thrombocytopenia are common. CONCLUSION: Dovitinib showed modest antitumor activity with manageable toxicities in men with mCRPC. Especially, patients who were chemo-naïve benefitted from dovitinib.

Pathomechanisms of pericyte-myofibroblast transition in kidney and interventional effects of Chinese herbal medicine / 中国中药杂志

In the kidney, pericyte is the major source of myofibroblast (MyoF) in renal interstitium. It is reported that pericyte-myofibroblast transition（PMT）is one of the important pathomechanisms of renal interstitial fibrosis（RIF）. Among them, the main reasons for promoting RIF formation include pericyte recruitment, activation and isolation, as well as the lack of pericyte-derived erythropoietin. During the PMT startup process, pericyte activation and its separation from microvessels are controlled by multiple signal transduction pathways, such as transforming growth factor-β（TGF-β）pathway, vascular endothelial growth factor receptor (VEGFR) pathway and platelet derived growth factor receptor (PDGFR) pathway;Blocking of these signaling pathways can not only inhibit PMT, but also suppress renal capillaries reduction and further alleviate RIF. In clinic, many traditional Chinese medicine compound prescriptions, single traditional Chinese herbal medicine (CHM) and their extracts have the clear effects in alleviating RIF, and some of their intervention actions may be related to pericyte and its PMT. Therefore, the studies on PMT and its drug intervention will become the main development direction in the research field of anti-organ fibrosis by CHM.

A Case of Myeloid Neoplasm with a PDGFRB Rearrangement and Eosinophilia / 대한내과학회지

Myeloid neoplasia with eosinophilia and platelet-derived growth factor receptor beta (PDGFRB) rearrangements is an uncommon Philadelphia-negative myeloproliferative neoplasm. Their most common morphological diagnosis is chronic myelomonocytic leukemia with eosinophilia, which is associated with t(5;12)(q33;p13) and results in the formation of the ETV6-PDGFRB fusion gene. Here, we report a 49-year-old man with a myeloid neoplasm with a PDGFRB rearrangement, who was incidentally diagnosed with hyperleukocytosis and eosinophilia during a health screening. A chromosome analysis of a bone marrow sample revealed 46, XY, t(5;12)(q33;p13), and fluorescence in situ hybridization analysis revealed the PDGFRB gene rearrangement. The patient was treated with imatinib and subsequently achieved complete hematological and molecular remission.

Platelet-Derived Growth Factor Receptor-Positive Pericytic Cells of White Adipose Tissue from Critical Limb Ischemia Patients Display Mesenchymal Stem Cell-Like Properties

BACKGROUND: The pericytes in the blood vessel wall have recently been identified to be important in regulating vascular formation, stabilization, remodeling, and function. We isolated and identified pericyte-like platelet-derived growth factor receptor beta-positive (PDGFRβ+) cells from the stromal vascular fraction (SVF) of adipose tissue from critical limb ischemia (CLI) patients and investigated their potential as a reliable source of stem cells for cell-based therapy. METHODS: De-identified subcutaneous fat tissues were harvested after amputation in CLI patients. Freshly isolated SVF cells and culture-expanded adipose-derived stem cells (ADSCs) were quantified using flow cytometry. A matrigel tube formation assay and multi-lineage differentiation were performed to assess pericytic and mesenchymal stem cell (MSC)-like characteristics of PDGFRβ+ ADSCs. RESULTS: PDGFRβ+ cells were located in the pericytic area of various sizes of blood vessels and coexpressed mesenchymal stem cell markers. PDGFRβ+ cells in freshly isolated SVF cells expressed a higher level of stem cell markers (CD34 and CXCR4) and mesenchymal markers (CD13, CD44, CD54, and CD90) than PDGFRβ– cells. In vitro expansion of PDGFRβ+ cells resulted in enrichment of the perivascular mesenchymal stem-like (PDGFRβ+/CD90+/CD45–/CD31–) cell fractions. The Matrigel tube formation assay revealed that PDGFRβ+ cells were located in the peritubular area. CONCLUSIONS: PDGFRβ+ ADSCs cells demonstrated a good multilineage differentiation potential. Pericyte-like PDGFRβ+ cells from the SVF of adipose tissue from CLI patients had MSC-like characteristics and could be amplified by in vitro culture with preservation of their cell characteristics. We believe PDGFRβ+ cells in the SVF of adipose tissue can be used as a reliable source of stem cells even in CLI patients.

VEGF and Ki-67 Overexpression in Predicting Poor Overall Survival in Adenoid Cystic Carcinoma / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The purpose of this study was to evaluate potential prognostic factors in patients with adenoid cystic carcinoma (ACC). MATERIALS AND METHODS: A total of 68 patients who underwent curative surgery and had available tissue were enrolled in this study. Their medical records and pathologic slides were reviewed and immunohistochemistry for basic fibroblast growth factor, fibroblast growth factor receptor (FGFR) 2, FGFR3, c-kit, Myb proto-oncogene protein, platelet-derived growth factor receptor beta, vascular endothelial growth factor (VEGF), and Ki-67 was performed. Univariate and multivariate analysis was performed for determination of disease-free survival (DFS) and overall survival (OS). RESULTS: In univariate analyses, primary site of nasal cavity and paranasal sinus (p=0.022) and Ki-67 expression of more than 7% (p=0.001) were statistically significant factors for poor DFS. Regarding OS, perineural invasion (p=0.032), high expression of VEGF (p=0.033), and high expression of Ki-67 (p=0.007) were poor prognostic factors. In multivariate analyses, primary site of nasal cavity and paranasal sinus (p=0.028) and high expression of Ki-67 (p=0.004) were independent risk factors for poor DFS, and high expression of VEGF (p=0.011) and Ki-67 (p=0.011) showed independent association with poor OS. CONCLUSION: High expression of VEGF and Ki-67 were independent poor prognostic factors for OS in ACC.

Efficacy of Imatinib in Patients with Platelet-Derived Growth Factor Receptor Alpha-Mutated Gastrointestinal Stromal Tumors / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The incidence of gastrointestinal stromal tumors (GISTs) harboring platelet-derived growth factor receptor alpha (PDGFRA) mutations is low, therefore further investigation of the efficacy of imatinib in this subgroup was needed. MATERIALS AND METHODS: Patients with PDGFRA-mutant GISTs who received imatinib as primary therapy for advanced disease between January 2000 and June 2012 were identified from the GIST registry of Asan Medical Center, Seoul, Korea. RESULTS: KIT and PDGFRA genotyping in 823 patients identified 18 patients (2%) with PDGFRA mutations who were treated with first-line imatinib. Exon 18 D842V substitution, non-D842V exon 18 mutations, and exon 12 mutations were detected in nine (50%), four (22%), and five (28%) patients, respectively. Objective response rate differed significantly between patients with the D842V mutation and those with non-D842V mutations (0% [0/5] vs. 71% [5/7], p=0.03). In all patients, median progression-free survival (PFS) and overall survival (OS) was 24.8 months (95% confidence interval [CI], 0.0 to 57.2) and 51.2 months (95% CI, 37.1 to 65.3), respectively. Significantly, poorer PFS was observed for patients with D842V-mutant GISTs than those with non-D842V PDGFRA-mutant GISTs: median 3.8 months (95% CI, 1.4 to 6.3) versus 29.5 months (95% CI, 18.3 to 40.7) (p < 0.001). Patients with the D842V mutation had poorer OS than those with non-D842V PDGFRA mutations: median 25.2 months (95% CI, 12.7 to 37.8) versus 59.8 months (95% CI, 43.0 to 76.5) (p=0.02). CONCLUSION: Imatinib is active against non-D842V PDGFRA-mutant GISTs, whereas GISTs harboring the D842V mutation are primarily resistant to imatinib.

Different anti-remodeling effect of nilotinib and fluticasone in a chronic asthma model

BACKGROUND/AIMS: Inhaled corticosteroids are the most effective treatment currently available for asthma, but their beneficial effect against airway remodeling is limited. The tyrosine kinase inhibitor nilotinib has inhibitory activity against c-kit and the platelet-derived growth factor receptor. We compared the effects of fluticasone and nilotinib on airway remodeling in a chronic asthma model. We also examined whether co-treatment with nilotinib and fluticasone had any synergistic effect in preventing airway remodeling. METHODS: We developed a mouse model of airway remodeling, including smooth muscle thickening, in which ovalbumin (OVA)-sensitized female BALB/c-mice were repeatedly exposed to intranasal OVA administration twice per week for 3 months. Mice were treated with fluticasone and/or nilotinib intranasally during the OVA challenge. RESULTS: Mice chronically exposed to OVA developed eosinophilic airway inflammation and showed features of airway remodeling, including thickening of the peribronchial smooth muscle layer. Both fluticasone and nilotinib attenuated airway smooth muscle thickening. However, only nilotinib suppressed fibrotic changes, demonstrating inhibition of collagen deposition. Fluticasone reduced pro-inflammatory cells, such as eosinophils, and several cytokines, such as interleukin 4 (IL-4), IL-5, and IL-13, induced by repeated OVA challenges. On the other hand, nilotinib reduced transforming growth factor β1 levels in bronchoalveolar lavage fluid and inhibited fibroblast proliferation significantly. CONCLUSIONS: These results suggest that fluticasone and nilotinib suppressed airway remodeling in this chronic asthma model through anti-inflammatory and anti-fibrotic pathways, respectively.

Serum Response Factor Is Essential for Prenatal Gastrointestinal Smooth Muscle Development and Maintenance of Differentiated Phenotype

BACKGROUND/AIMS: Smooth muscle cells (SMCs) characteristically express serum response factor (SRF), which regulates their development. The role of SRF in SMC plasticity in the pathophysiological conditions of gastrointestinal (GI) tract is less characterized. METHODS: We generated SMC-specific Srf knockout mice and characterized the prenatally lethal phenotype using ultrasound biomicroscopy and histological analysis. We used small bowel partial obstruction surgeries and primary cell culture using cell-specific enhanced green fluorescent protein (EGFP) mouse lines to study phenotypic and molecular changes of SMCs by immunofluorescence, Western blotting, and quantitative polymerase chain reaction. Finally we examined SRF change in human rectal prolapse tissue by immunofluorescence. RESULTS: Congenital SMC-specific Srf knockout mice died before birth and displayed severe GI and cardiac defects. Partial obstruction resulted in an overall increase in SRF protein expression. However, individual SMCs appeared to gradually lose SRF in the hypertrophic muscle. Cells expressing low levels of SRF also expressed low levels of platelet-derived growth factor receptor alpha (PDGFRalphalow) and Ki67. SMCs grown in culture recaptured the phenotypic switch from differentiated SMCs to proliferative PDGFRalphalow cells. The immediate and dramatic reduction of Srf and Myh11 mRNA expression confirmed the phenotypic change. Human rectal prolapse tissue also demonstrated significant loss of SRF expression. CONCLUSIONS: SRF expression in SMCs is essential for prenatal development of the GI tract and heart. Following partial obstruction, SMCs down-regulate SRF to transition into proliferative PDGFRalphalow cells that may represent a phenotype responsible for their plasticity. These findings demonstrate that SRF also plays a critical role in the remodeling process following GI injury.

The Physiologic Roles of the Subepithelial Platelet-derived Growth Factor Receptor alpha-positive Cells in the Colon (Am J Physiol Gastrointest Liver Physiol 2013;304:G823-G834)

No abstract available.

The Significance of Interstitial Cells in Neurogastroenterology

Smooth muscle layers of the gastrointestinal tract consist of a heterogeneous population of cells that include enteric neurons, several classes of interstitial cells of mesenchymal origin, a variety of immune cells and smooth muscle cells (SMCs). Over the last number of years the complexity of the interactions between these cell types has begun to emerge. For example, interstitial cells, consisting of both interstitial cells of Cajal (ICC) and platelet-derived growth factor receptor alpha-positive (PDGFRalpha+) cells generate pacemaker activity throughout the gastrointestinal (GI) tract and also transduce enteric motor nerve signals and mechanosensitivity to adjacent SMCs. ICC and PDGFRalpha+ cells are electrically coupled to SMCs possibly via gap junctions forming a multicellular functional syncytium termed the SIP syncytium. Cells that make up the SIP syncytium are highly specialized containing unique receptors, ion channels and intracellular signaling pathways that regulate the excitability of GI muscles. The unique role of these cells in coordinating GI motility is evident by the altered motility patterns in animal models where interstitial cell networks are disrupted. Although considerable advances have been made in recent years on our understanding of the roles of these cells within the SIP syncytium, the full physiological functions of these cells and the consequences of their disruption in GI muscles have not been clearly defined. This review gives a synopsis of the history of interstitial cell discovery and highlights recent advances in structural, molecular expression and functional roles of these cells in the GI tract.

Platelet derived growth factor receptor β over-expression in endothelial progenitor cells promote reendothelialization after vascular injury / 中华心血管病杂志

<p><b>OBJECTIVE</b>To observe the effect of platelet derived growth factor receptor β (PDGFR-β) transfected endothelial progenitor cells (EPCs) on vascular regeneration.</p><p><b>METHODS</b>Spleen-derived mononuclear cells (MNCs) were isolated using density gradient centrifugation and induced with special culture medium. EPCs transfection was performed with Lipofectamine(TM) 2000 reagent according to the instruction manual. Carotid artery injury was induced in splenectomized mice. EPCs were injected by tail vein immediately and at 24 h after endothelial injury of the carotid artery. Evans blue staining was performed to evaluate reendothelialization at 7 days after endothelial injury of the carotid artery.</p><p><b>RESULTS</b>Most adherent cells were LDL and UEA-I double positive. Laser scanning confocal microscopy showed that transfection efficiency was about 50%-60%. The reendothelialized area in the PDGFR-β-EPCs group was significantly larger than that in EGFP-EPCs group.</p><p><b>CONCLUSION</b>Transplantation of PDGFR-β over-expressed EPCs can promote reendothelialization in the early phase after carotid artery injury.</p>

Platelet receptors: an instrumental of platelet physiology

Platelets play an important role in hemostasis, inflammation, host defense, tumor growth and metastasis. Platelets receptors are instrumental in platelet-platelet aggregation and interaction of platelets with leukocytes, endothelial cells and coagulation factors. These receptors are also the targets for antiplatelet drugs. This review focuses on the role of platelet receptors in human physiology. Data were extracted from peer-reviewed journals using MEDLINE and EMBASE databases, and the following terms [platelets, platelet receptors, CD markers, integrins, tetraspanins, transmembrane receptors, prostaglandin receptors, immunoglobulin superfamily receptors] were used

The KIT Exon 11 Stop Codon Mutation in Gastrointestinal Stromal Tumors: What Is the Clinical Meaning?

BACKGROUND/AIMS: Gastrointestinal stromal tumors (GISTs) strongly express a receptor tyrosine kinase (RTK, c-KIT-CD117) harboring a KIT mutation that causes constitutive receptor activation leading to the development and growth of tumors; 35% of GISTs without KIT mutations have platelet-derived growth factor receptor alpha (PDGFRA) mutations, and the type of mutation plays an important role in the response to treatment. This study aimed to establish the frequency of stop codon mutations in the RTKs, KIT, and PDGFRA, in GISTs and correlate this molecular alteration with protein expression and treatment responsiveness. METHODS: Seventy-nine GISTs were analyzed for both KIT and PDGFRA mutations. Immunohistochemical expression was studied in tissue microarray blocks. RESULTS: We found three rare KIT mutations in exon 11 that induced a stop codon, two at position 563 and one at position 589, which have never been described before. All three tumors were CD117-, DOG1-, and CD34-positive. Two patients with a KIT stop codon mutation did not respond to imatinib therapy and died shortly after treatment. CONCLUSIONS: The association between stop codon mutations in KIT and patient survival, if confirmed in a larger population, may be useful in choosing effective therapies.

Ionic Conductance(s) in Response to Post-junctional Potentials

The gastrointestinal motility is regulated by extrinsic and intrinsic neural regulation. Intrinsic neural pathways are controlled by sensory input, inter-neuronal relay and motor output. Enteric motor neurons release many transmitters which affect post-junctional responses. Post-junctional responses can be excitatory and inhibitory depending on neurotransmitters. Excitatory neurotransmitters induce depolarization and contraction. In contrast, inhibitory neurotransmitters hyperpolarize and relaxe the gastrointestinal smooth muscle. Smooth muscle syncytium is composed of smooth muscle cells, interstitial cells of Cajal and platelet-derived growth factor receptor alpha-positive (PDGFRalpha+) cells (SIP syncytium). Specific expression of receptors and ion channels in these cells can be affected by neurotransmitters. In recent years, molecular reporter expression techniques are able to study the properties of ion channels and receptors in isolated specialized cells. In this review, we will discuss the mechanisms of ion channels to interpret the post-junctional responses in the gastrointestinal smooth muscles.

Role of Angiogenic Factors in Airway Remodeling in an Allergic Rhinitis Murine Model

PURPOSE: There is growing evidence that nasal airway remodeling occurs in allergic rhinitis (AR). Although angiogenesis is an important component of airway remodeling in asthma, its involvement in AR has been little studied. Furthermore, information regarding the role of potent angiogenic factors, such as vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF), in the nasal airway remodeling process is limited. This study was conducted to investigate the role of VEGF and PDGF in nasal airway remodeling, and to assess the preventive effects of anti-angiogenic drugs on this process in a murine AR model. METHODS: Mice were systemically sensitized and subjected to inhalation of ovalbumin (OVA) twice a week for 3 months. Control mice were challenged with phosphate buffered saline, while the treatment group received SU1498, a VEGF receptor inhibitor, and/or AG1296, a PDGF receptor inhibitor, via intraperitoneal injection 4 hours prior to each OVA inhalation. Staining using hematoxylin and eosin, Masson's trichrome, and periodic acid-Schiff were separately performed to assess eosinophil infiltration, subepithelial fibrosis, and goblet cell hyperplasia, respectively, in the nasal airway. Immunohistochemical staining for matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) was also conducted. RESULTS: Repetitive intranasal inhalation of OVA resulted in significant increases in eosinophil infiltration, subepithelial fibrosis, goblet cell count, and MMP-9/TIMP-1 expression. Administration of SU1498 or AG1296 prevented these abnormal responses. CONCLUSIONS: The results of this study suggest that a causal relationship may exist between angiogenic factors and nasal airway remodeling in AR. Inhibition of VEGF or PDGF receptors may, in turn, suppress the remodeling process through the regulation of MMP-9/TIMP-1 expression.

Target Therapy for Hepatocellular Carcinoma / 한양의대학술지

Hepatocellular carcinoma (HCC) is a highly malignant tumor that has limited treatment options in its advanced state. The efficacy of current anti-cancer chemotherapy in advanced HCC has not been satisfactory, and the management of HCC remains a major challenge for physicians. However, recent advancement in our understanding of the molecular mechanisms underlying carcinogenesis has provided novel targets in key signaling pathways for tumor development. Recently, Sorafenib (Nexavar), a multi-kinase inhibitor targeting membrane receptors involved in angiogenic and mitogenic intra-cellular signaling including Raf, vascular endothelial growth factor receptor (VEGFR), and platelet-derived growth factor receptors (PDGFR), has been approved worldwide as a new target agent for HCC, and subsequent clinical trials of newly developed molecular target agents such as Brivanib and Everolimus are being conducted globally. In the near future, continued research will lead to the identification of additional molecular targets in HCC and lead to treatments with enhanced efficacy and improved tolerability.

Smooth Muscles Contraction in Gastrointestinal Tract and New Concept of Enteric Neurotransmission: Fibroblast-like Cells / 대한내과학회지

This review provides information regarding an enteric neurotransmission from enteric nerve terminals to smooth muscles. In the gastrointestinal tract, phasic contractions are caused by electrical activity termed slow waves. Slow waves are generated and actively propagated by interstitial cells of Cajal (ICC). The initiation of pacemaker activity in the ICC is caused by release of Ca2+ from inositol 1, 4, 5-trisphosphate (IP3) receptor-operated stores, and the development of unitary currents. Summation of unitary currents causes depolarization and activation of a dihydropyridine-resistant Ca2+ conductance that entrains pacemaker activity in a network of ICC, resulting in the active propagation of slow waves. Slow wave frequency is regulated by a variety of physiological agonists and conditions, and shifts in pacemaker dominance can occur in response to both neural and non-neural inputs. Fibroblast-like cells (FLCs) are also closely associated with nerve varicosities and are labelled robustly with antibodies for platelet-derived growth factor receptor alpha (PDGFRalpha), and expression of this receptor may be a powerful new means of isolating and evaluating the function of FLCs and the possible contribution of these cells in disease. PDGFRalpha+ cells share similar anatomical distributions, and FLCs in colonic smooth muscle functionally express small conductance Ca(2+)-activated K+ channel (SK3). These findings are important to understand purinergic post-junctional responses.

Imatinib Mesylate (Gleevec(TM))-induced Lichenoid Drug Eruption Improved by Tentative Dose-reduction and Topical Steroid / 대한피부과학회지

Imatinib mesylate (Gleevec(TM)) is an oral anticancer drug. It works as a selective and competitive inhibitor of tyrosine kinases such as bcr-abl protein, c-kit, and platelet-derived growth factor receptors (PDGFR). Gleevec(TM) is a first-line therapeutic agent for chronic myelogenous leukemia (CML) and gastrointestinal stromal tumors, but causes various adverse cutaneous reactions. We herein report on a case of lichenoid drug eruption induced by Gleevec(TM) in a patient with a malignant gastrointestinal stromal tumor.

Combined Treatment with Anticancer Vaccine Using Genetically Modified Endothelial Cells and Imatinib in Bladder Cancer

PURPOSE: We sought to maximize the antitumor effect of an anticancer vaccine based on genetically modified endothelial cells by combining it with the platelet-derived growth factor receptor inhibitor imatinib. MATERIALS AND METHODS: Human umbilical vein endothelial cells (HUVECs) were infected with 10 MOI of Ad-CMV-mGMCSF to make anticancer vaccines. One million mouse bladder cancer cells (MBT-2) were subcutaneously inoculated in C3H mice. The experimental groups included the following: Group 1 (phosphate-buffered saline), Group 2 (anticancer vaccine and GM-CSF), Group 3 (imatinib), and Group 4 (anticancer vaccine, GM-CSF, and imatinib). Tumor growth and body weight were measured weekly. At 4 weeks, the tumors were immunostained with anti-CD31, and microvessel density (MVD) was measured. To evaluate the immunological mechanism of each treatment, flow cytometry analysis of activated CD4 and CD8 cells was performed. RESULTS: At 4 weeks, the mean body weight of each group, excluding the extracted tumor weight, was not significantly different. Since week 3, the mean tumor volume in Group 4 was the smallest among the treatment groups (p<0.05), and a synergistic suppressive effect on tumor volume was observed in Group 4. The MVD in Group 4 was the most suppressed among the treatment groups (p<0.05), and a synergistic anti-angiogenic effect was observed. Flow cytometry analysis revealed that activated CD4+ and CD8+ cells increased in Group 2 and decreased in Group 3 compared with the other groups. CONCLUSIONS: The combination of genetically modified endothelial cell vaccines and imatinib showed a synergistic antiangiogenic effect in bladder cancer.

The role of PDGF/PDGFR in the regulation of platelet formation / 中国实验血液学杂志

Platelet-derived growth factor (PDGF), a potent chemotactic and mitogenic factor, is involved in the regulation of hematopoiesis and platelet production. Our studies demonstrate the presence of functional PDGF receptors (PDGFR) on human megakaryocytes/platelets and CD34(+) cells, and their ability to mediate a mitogenic response. PDGF promotes the ex vivo expansion of human hematopoietic stem (CD34(+)) and progenitor (CD41(+)) cells. More significantly, PDGF enhances the engraftment of human CD45(+) cells and their myeloid subsets (CD33(+), CD14(+) cells) in NOD/SCID mice. PDGF also stimulates in vitro megakaryocytopoiesis via PDGFR and/or the indirect effect on bone marrow microenvironment to produce TPO and other cytokines. It also shows a direct stimulatory effect of PDGF on c-Fos, GATA-1 and NF-E2 expressions in megakaryocytes. We speculate that these transcription factors may be involved in the signal transduction of PDGF on the regulation of megakaryocytopoiesis. PDGF also enhances platelet recovery in mouse model with radiation-induced thrombocytopenia. This radioprotective effect is likely to be mediated via PDGFR with subsequent activation of the PI3K/Akt pathway. It provides a possible explanation that blockage of PDGFR may reduce thrombopoiesis and play a role in imatinib mesylate-induced thrombocytopenia.