Stromal Factor Research Articles

Mobilization of Endothelial Progenitor Cells From Bone Marrow is Impaired in a Piglet Model of Acute Respiratory Distress Syndrome*

To characterize the endothelial progenitor cell mobilization in the models of moderate and severe lung injury, we hypothesized that there were differences in endothelial progenitor cell levels and mobilizing cytokines between moderate and severe lung injury. Prospective, randomized, and controlled experimental study. University research laboratory center. Fifteen healthy piglets. Piglets were randomly allocated to control, moderate lung injury (acute lung injury), and severe lung injury (acute respiratory distress syndrome) groups. Lung injury was established by intravenous infusion of oleic acid. Animals were mechanically ventilated for 24-48 hours, and then animals were weaned from ventilation and cared for until day 7. Endothelial progenitor cells were quantified by flow cytometry. After 24 hours, the number of endothelial progenitor cells in peripheral blood increased in the acute lung injury group but was not altered in the acute respiratory distress syndrome group compared to the control group. The number of CD34KDR, KDRCD133, and CD34KDRCD133 cells was higher in the acute lung injury group than in the acute respiratory distress syndrome group. In bone marrow, the number of CD34KDR and KDRCD133 cells was greater in acute respiratory distress syndrome animals but not altered in acute lung injury animals at 24 hours. Furthermore, plasma stromal cell-derived factor-1 and vascular endothelial growth factor concentrations were higher in acute lung injury than in acute respiratory distress syndrome at 24 hours. Matrix metalloproteinase-9 and soluble kit ligand levels in bone marrow were reduced in acute respiratory distress syndrome compared with acute lung injury. Lung CD34, KDR, and lung stromal cell-derived factor-1 messenger RNA expression were higher in the acute lung injury group than in the acute respiratory distress syndrome group. Furthermore, the expression of CD34, KDR, and CD133 messenger RNA in lung tissue was correlated with stromal cell-derived factor-1 in the lung. There was a rapid release of endothelial progenitor cells from bone marrow into circulation in moderate acute lung injury, and endothelial progenitor cell mobilization was impaired in acute respiratory distress syndrome.

Fibroblast growth factor-1 is a mesenchymal stromal cell-secreted factor stimulating proliferation of osteoarthritic chondrocytes in co-culture.

Previously, we showed that mesenchymal stromal cells (MSCs) in co-culture with primary chondrocytes secrete soluble factors that increase chondrocyte proliferation. The objective of this study is to identify these factors. Human primary chondrocytes (hPCs) isolated from late-stage osteoarthritis patients were co-cultured with human bone marrow-derived MSCs (hMSCs) in pellets. Genome-wide mRNA expression analysis and quantitative polymerase chain reactions (qPCR) were used to identify soluble factors that were specifically induced in co-cultures. Immunofluorescent staining combined with cell tracking and enzyme-linked immunosorbent assay (ELISA) were performed to validate up-regulation at the protein level and to identify the cellular origin of the increased proteins. Chemical blockers and neutralizing antibodies were used to elucidate the role of the identified candidate genes in co-cultures. A number of candidate factors were differentially regulated in co-cultures at the mRNA level. Of these, fibroblast growth factor-1 (FGF-1) mRNA and protein expression were markedly increased in co-cultures predominantly due to up-regulated expression in MSCs. Blocking of FGF signaling in co-culture pellets by specific FGF receptor inhibitors or FGF-1 neutralizing antibodies completely blocked hPCs proliferation. We demonstrate that MSCs increase FGF-1 secretion on co-culture with hPCs, which, in turn, is responsible for increased hPCs proliferation in pellet co-cultures.

Stromal Insulin-Like Growth Factor Binding Protein 3 (IGFBP3) Is Elevated in the Diseased Human Prostate and Promotes ex Vivo Fibroblast-to-Myofibroblast Differentiation

Dysregulation of the IGF axis is implicated in the development of benign prostatic hyperplasia (BPH) and prostate cancer (PCa), 2 of the most common diseases affecting elderly males. PCa is the second leading cause of male-related cancer death in Western societies. Although distinct pathologies, BPH and PCa are both characterized by extensive stromal remodeling, in particular fibroblast-to-myofibroblast differentiation, thought to be induced by elevated local production of TGFβ1. We previously showed that TGFβ1-mediated fibroblast-to-myofibroblast differentiation of primary human prostatic stromal cells resulted in the dsyregulation of several components of the IGF axis, including the induction of IGF binding protein 3 (IGFBP3). Using isoform-specific lentiviral-mediated knockdown, we demonstrate herein that IGFBP3 is essential for TGFβ1-mediated differentiation. Although recombinant human IGFBP3 alone was not sufficient to induce differentiation, IGFBP3 synergistically potentiated TGFβ1-mediated stromal remodeling predominantly via an IGF-independent mechanism. Consistent with these in vitro findings, IGFBP3 immunohistochemistry revealed elevated levels of IGFBP3 in the hyperplastic fibromuscular stroma of BPH specimens and in the tumor-adjacent stroma of high-grade PCa. Collectively these data indicate that the dysregulation of the stromal IGF axis, in particular elevated IGFBP3, plays a crucial role in fibroblast-to-myofibroblast differentiation in the diseased prostatic stroma and indicate the therapeutic potential of inhibiting stromal remodeling and the resulting dysregulation of the stromal IGF axis as a novel strategy for the treatment of advanced PCa and BPH.

Bovine Endometrial Stromal Cells Support Tumor Necrosis Factor Alpha-Induced Bovine Herpesvirus Type 4 Enhanced Replication1

Bovine uterine infections are the most important cause of economic losses in the cattle industry. Although the etiology of uterine diseases is mainly ascribed to bacterial infection, they can also be associated with viral infection, such as bovine herpesvirus 4 (BoHV-4), which is often a secondary agent following bacteria. Besides microbial infection, many inflammatory molecules belonging to the innate immune response orchestrate the outcome of the infection. In the present study, the interaction between BoHV-4-infected bovine endometrial stromal cells and tumor necrosis factor alpha (TNF-alpha) was investigated. Bovine herpesvirus 4 possesses a special tropism toward endometrial stromal cells. For this reason, a simian virus 40 (SV40) immortalized endometrial stromal cell line (SV40BESC) was established; it was proven that it was stable, it expressed toll-like receptors (TLRs; from 1 to 10) and TNF-alpha receptors I and II, and it was responsive to exogenous TNF-alpha. Further, an increase of BoHV-4 replication and cytopathic effect was observed in BoHV-4-infected and TNF-alpha-treated SV40BESCs. This increase of viral replication was associated with BoHV-4 immediate early 2 (IE2) gene promoter trans-activation through the interaction of the nuclear factor KB (NFKB) with the putative NFKB-responsive elements found within BoHV-4 IE2 gene promoter, and this interaction was abolished when NFKB-responsive elements were deleted. These data shed light on two important and rather controversial issues: the role of TNF-alpha receptor, which is weakly expressed in the stromal layer of the bovine uterus, as well as the possible interactions between proinflammatory molecules, viral replication, and chronic uterine disease.

Shock wave treatment induces angiogenesis and mobilizes endogenous CD31/CD34-positive endothelial cells in a hindlimb ischemia model: Implications for angiogenesis and vasculogenesis

Shock waves have been shown to induce recruitment of intravenously injected endothelial progenitor cells to ischemic hind limbs in rats. We hypothesized that shock wave treatment as sole therapy would induce angiogenesis in this ischemia model and would lead to mobilization of endogenous endothelial (progenitor) cells. A total of 18 rats, aged 5 weeks old, were subdivided into 3 groups: sham (n=6), ischemic muscle with shock wave treatment (shock wave treatment group, n=6), and without shock wave treatment (control, n=6). Hind limb ischemia was induced by ligation of the femoral artery. Three weeks later, shock wave treatment (300 impulses at 0.1 mJ/mm(2)) was applied to the adductor muscle; the controls were left untreated. Muscle samples were analyzed using real-time polymerase chain reaction for angiogenic factors and chemoattractants for endothelial progenitor cell mobilization. Fluorescence activated cell sorting analysis of the peripheral blood was performed for CD31/CD34-positive cells. Perfusion was measured using laser Doppler imaging. Functional improvement was evaluated by walking analysis. Angiogenic factors/endothelial progenitor cell chemoattractants, stromal cell-derived factor-1 and vascular endothelial growth factor, were increased in the treatment group, as shown by real-time polymerase chain reaction, indicating the mobilization of endothelial progenitor cells. Fluorescence activated cell sorting analysis of the peripheral blood revealed high numbers of CD31/CD34-positive cells in the treatment group. Greater numbers of capillaries were found in the treated muscles. Blood perfusion increased markedly in the treatment group and led to functional restoration, as shown by the results from the walking analysis. Shock wave therapy therefore could develop into a feasible alternative to stem cell therapy in regenerative medicine, in particular for ischemic heart and limb disease.

The concentration of human follicular fluid stromal cell-derived factor-1 is correlated with luteinization in follicles

Stromal cell-derived factor-1 (SDF-1/CXCL12) and vascular endothelial growth factor (VEGF) are angiogenic factors that have possible roles in ovarian function. The objectives of this study were to investigate the association between the individual concentrations of SDF-1 and VEGF and sex steroid hormones in human preovulatory follicles and to verify the SDF-1 expression in ovarian follicles. Follicular fluid (FF) and luteinizing granulosa cells (LGCs) were collected from follicles at the time of oocyte retrieval. The concentrations of SDF-1, VEGF, estradiol (E2) and progesterone (P4) were determined by biochemical assay. The expression levels of SDF-1 mRNA and protein were analyzed by RT-PCR and immunohistochemical analysis, respectively. A total of 177 follicles were analyzed. The FF concentrations of SDF-1 and VEGF positively correlated with P4 concentrations (r = 0.457 and p < 0.01, r = 0.698 and p < 0.01, respectively), but did not correlate with E2 concentrations in FF. Furthermore, we confirmed that SDF-1 mRNA was expressed in LGCs and SDF-1 protein is present in the granulosa cells of the human ovary. Our findings suggest that SDF-1, as well as VEGF, may play important modulatory roles in early luteinization of human preovulatory follicles.

Effects of Korean red ginseng extract on the prevention of atopic dermatitis and its mechanism on early lesions in a murine model

Ethnopharmacological relevanceKorean red ginseng (KRG) has been shown to possess various biological activities including anti-inflammatory properties. Aim of the studyWe aimed to investigate the effects and mechanism of KRG on the prevention of atopic dermatitis (AD) using a mouse model. Materials and methodsThe effect of KRG in trinitrochlorobenzene (TNCB)-treated NC/Nga mice was assessed by measuring ear thickness, transepidermal water loss (TEWL), total serum IgE, histologic changes of lesional skin, mRNA and protein expression of thymic stromal lymphopoietin (TSLP) and tumor necrosis factor (TNF)-α, immunohistochemistry for tissue interleukin (IL)-4, IL-17, and interferon (IFN)-γ. ResultsKRG significantly reduced ear thickness. Oral administration of KRG significantly prevented the increase in TEWL induced by TNCB. The serum IgE level was significantly lower in the KRG group. Histologically, lymphocyte infiltration was markedly decreased by KRG. CD1a positive (CD1a+) cells were diminished by KRG. Immunohistochemically, KRG significantly suppressed the protein expression of TSLP and TNF-α. The mRNA expression of TSLP in the lesions was significantly reduced by KRG. These results demonstrate that oral administration of KRG may inhibit the development of AD-like skin lesions in NC/Nga mice by modifying TSLP, DCs, and at least in part, the Th2 response. ConclusionKRG may be a potential therapeutic modality for the prevention of AD.

Hepatocyte growth factor in the neighborhood reverses resistance to BRAF inhibitor in melanoma

Hepatocyte growth factor in the neighborhood reverses resistance to <scp>BRAF</scp> inhibitor in melanoma

Tumor stromal vascular endothelial growth factor A is predictive of poor outcome in inflammatory breast cancer

BackgroundInflammatory breast cancer (IBC) is a highly angiogenic disease; thus, antiangiogenic therapy should result in a clinical response. However, clinical trials have demonstrated only modest responses, and the reasons for these outcomes remain unknown. Therefore, the purpose of this retrospective study was to determine the prognostic value of protein levels of vascular endothelial growth factor (VEGF-A), one of the main targets of antiangiogenic therapy, and its receptors (VEGF-R1 and -R2) in IBC tumor specimens.Patients and MethodsSpecimens from IBC and normal breast tissues were obtained from Algerian patients. Tumor epithelial and stromal staining of VEGF-A, VEGF-R1, and VEGF-R2 was evaluated by immunohistochemical analysis in tumors and normal breast tissues; this expression was correlated with clinicopathological variables and breast cancer-specific survival (BCSS) and disease-free survival (DFS) duration.ResultsFrom a set of 117 IBC samples, we evaluated 103 ductal IBC tissues and 25 normal specimens. Significantly lower epithelial VEGF-A immunostaining was found in IBC tumor cells than in normal breast tissues (P <0.01), cytoplasmic VEGF-R1 and nuclear VEGF-R2 levels were slightly higher, and cytoplasmic VEGF-R2 levels were significantly higher (P = 0.04). Sixty-two percent of IBC tumors had high stromal VEGF-A expression. In univariate analysis, stromal VEGF-A levels predicted BCSS and DFS in IBC patients with estrogen receptor-positive (P <0.01 for both), progesterone receptor-positive (P = 0.04 and P = 0.03), HER2+ (P = 0.04 and P = 0.03), and lymph node involvement (P <0.01 for both). Strikingly, in a multivariate analysis, tumor stromal VEGF-A was identified as an independent predictor of poor BCSS (hazard ratio [HR]: 5.0; 95% CI: 2.0-12.3; P <0.01) and DFS (HR: 4.2; 95% CI: 1.7-10.3; P <0.01).ConclusionsTo our knowledge, this is the first study to demonstrate that tumor stromal VEGF-A expression is a valuable prognostic indicator of BCSS and DFS at diagnosis and can therefore be used to stratify IBC patients into low-risk and high-risk groups for death and relapses. High levels of tumor stromal VEGF-A may be useful for identifying IBC patients who will benefit from anti-angiogenic treatment.

Release of TGFβig-h3 by gastric myofibroblasts slows tumor growth and is decreased with cancer progression

Tumor progression has been linked to changes in the stromal environment. Myofibroblasts are stromal cells that are often increased in tumors but their contribution to cancer progression is not well understood. Here, we show that the secretomes of myofibroblasts derived from gastric cancers [cancer-associated myofibroblasts (CAMs)] differ in a functionally significant manner from those derived from adjacent tissue [adjacent tissue myofibroblasts (ATMs)]. CAMs showed increased rates of migration and proliferation compared with ATMs or normal tissue myofibroblasts (NTMs). Moreover, conditioned medium (CM) from CAMs significantly stimulated migration, invasion and proliferation of gastric cancer cells compared with CM from ATMs or NTMs. Proteomic analysis of myofibroblast secretomes revealed decreased abundance of the extracellular matrix (ECM) adaptor protein like transforming growth factor-β-induced gene-h3 (TGFβig-h3) in CAMs, which was correlated with lymph node involvement and shorter survival. TGFβig-h3 inhibited IGF-II-stimulated migration and proliferation of both cancer cells and myofibroblasts, and suppressed IGF-II activation of p42/44 MAPkinase; TGFβig-h3 knockdown increased IGF-II- and CM-stimulated migration. Furthermore, administration of TGFβig-h3 inhibited myofibroblast-stimulated growth of gastric cancer xenografts. We conclude that stromal cells exert inhibitory as well as stimulatory effects on tumor cells; TGFβig-h3 is a stromal inhibitory factor that is decreased with progression of gastric cancers.

Erythropoietin improves the efficiency of endothelial progenitor cell therapy after myocardial infarction in mice: Effects on transplanted cell survival and autologous endothelial progenitor cell mobilization

BackgroundEndothelial progenitor cells (EPCs) participate in vascular repair and angiogenesis. Thus, EPC transplantation into ischemic myocardium might improve cardiac function; however, the vast majority of cells die within a short period. The present study was designed to investigate whether exogenous erythropoietin (EPO) delivery could improve the survival of transplanted EPCs and enhance the efficiency of EPC-based cell therapy. MethodsMyocardial infarction was induced in wild-type mice by ligating the left anterior descending coronary artery. Enhanced green fluorescent protein-EPCs with or without EPO were transplanted into peri-infarct myocardium. Enhanced green fluorescent protein-EPCs were detected 7 and 28 d after surgery. The amount of circulating EPCs was analyzed 3 and 28 d after surgery. The stromal cell-derived factor-1α and vascular endothelial growth factor concentrations, microvessel density, apoptosis, fibrosis in the peri-infarct myocardium, and cardiac function were compared among the groups. ResultsMore enhanced green fluorescent protein-EPCs were found in the hearts treated with EPC + EPO than in those treated with EPC alone. The circulating EPC level was markedly elevated after EPC + EPO treatment compared with EPC application alone. Stromal cell-derived factor-1α and vascular endothelial growth factor were increased accordingly, along with increased microvessel density, decreased apoptosis, and reduced fibrosis in the peri-infarct myocardium. Left ventricular fractional shortening was greater and the interventricular septum was thicker after EPC + EPO treatment compared with EPC treatment alone. ConclusionsEPO improved the efficiency of EPC therapy in mice with myocardial infarction. This effect was associated with enhanced transplanted EPC survival and autologous EPC mobilization.

Experiment study of SDF-1 expression during the survival process of the narrow pedicle flap with hypoxia and ischemia

To detect the stromal cell derived factor 1 (SDF-1) expression during the survival process of the narrow pedicle flap with hypoxia and ischemia and to investigate the role of SDF-1/ CXCR4 axis in flap neovascularization. The narrow pedicle flaps were formed on the bilateral back of 5 pigs. The pedicle ratio of length to width was 4:2. The flap size was 2 cm x 2 cm (group A), 3 cm x 3 cm (group B), 4 cm x 4 cm (group C), 5 cm x 5 cm(group D), 6 cm x6 cm (group E). The flaps survival rate was observed and HE staining was performed. The SDF-1 expression at the distal end of flaps was detected by ELISA during the operation and 3, 5, 7, 14 days after operation. (1) SDF-1 expression at the same group increased after operation until it reached the peak value at 5 days after operation; then it decreased to basic value. (2) SDF-1 expression in different groups was higher in bigger flaps until the flaps size reached 5 cm x 5 cm. Then partial necrosis happened at the distal end of flaps. The SDF-1 expression may be related to the blood supply during the survival process of the narrow pedicle flap with hypoxia and ischemia.

CD99 is a novel prognostic stromal marker in non‐small cell lung cancer

The complex interaction between cancer cells and the microenvironment plays an essential role in all stages of tumourigenesis. Despite the significance of this interplay, alterations in protein composition underlying tumour-stroma interactions are largely unknown. The aim of this study was to identify stromal proteins with clinical relevance in non-small cell lung cancer (NSCLC). A list encompassing 203 stromal candidate genes was compiled based on gene expression array data and available literature. The protein expression of these genes in human NSCLC was screened using the Human Protein Atlas. Twelve proteins were selected that showed a differential stromal staining pattern (BGN, CD99, DCN, EMILIN1, FBN1, PDGFRB, PDLIM5, POSTN, SPARC, TAGLN, TNC and VCAN). The corresponding antibodies were applied on tissue microarrays, including 190 NSCLC samples, and stromal staining was correlated with clinical parameters. Higher stromal expression of CD99 was associated with better prognosis in the univariate (p = 0.037) and multivariate (p = 0.039) analysis. The association was independent from the proportion of tumour stroma, the fraction of inflammatory cells and clinical and pathological parameters like stage, performance status and tumour histology. The prognostic impact of stromal CD99 protein expression was confirmed in an independent cohort of 240 NSCLC patients (p = 0.008). Furthermore, double-staining confocal fluorescence microscopy showed that CD99 was expressed in stromal lymphocytes as well as in cancer-associated fibroblasts. Based on a comprehensive screening strategy the membrane protein CD99 was identified as a novel stromal factor with clinical relevance. The results support the concept that stromal properties have an important impact on tumour progression.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Effects of hypoxia inducible factor-1α activator on the biological behavior of endothelial progenitor cells

Objective To investigate the effects of hypoxia inducible factor-1α （HIF-1α） on the proliferation, migration and angiogenesis of bone marrow-derived endothelial progenitor cells （EPCs）. Methods Bone marrow EPCs were interfered with the HIF-1α activator, dimethyloxalylglycine （DMOG） at different concentrations. Methyl thiazol tetrazolium （MTT） assay, CFU assay and Western blotting were employed. Nitric oxide （NO） production, vascular endothelial growth factor （ VEGF）, stromal cell derived factor 1 （SDF-1）, migratory capacity, cellular senescence levels and angiogenesis ability were evaluated. Results DMOG could significantly activate the expression of HIF-1α protein in EPCs and increase the cell viability in a dose-dependent fashion, which at peak proliferation at concentration of 500 μmol/L. DMOG could substantially improve the colony-forming ability （P 〈 0. 01 ） and significantly protect EPCs from cellular senescence （P 〈 0. 05 ）. Besides, DOMG ameliorated the migratory functions and angiogenesis ability of EPCs. Conclusion DMOG can activate HIF-1α and act on EPCs to improve the proliferation, migration capacities and angiogenesis ability. Key words: Endothelial progenitor ceils ; Dimethyloxalylglycine ; Hypoxia inducible factor-1α; Angiogenesis

Adult Neural Stem Cells: Response to Stroke Injury and Potential for Therapeutic Applications

The plasticity of neural stem/progenitor cells allows a variety of different responses to many environmental cues. In the past decade, significant research has gone into understanding the regulation of neural stem/progenitor cell properties, because of their promise for cell replacement therapies in adult neurological diseases. Both endogenous and grafted neural stem/progenitor cells are known to have the ability to migrate long distances to lesioned sites after brain injury and differentiate into new neurons. Several chemokines and growth factors, including stromal cell-derived factor-1 and vascular endothelial growth factor, have been shown to stimulate the proliferation, differentiation, and migration of neural stem/progenitor cells, and investigators have now begun to identify the critical downstream effectors and signaling mechanisms that regulate these processes. Both our own lab and others have shown that the extracellular matrix and matrix remodeling factors play a critical role in directing cell differentiation and migration of adult neural stem/progenitor cells within injured sites. Identification of these and other molecular pathways involved in stem cell homing into ischemic areas is vital for the development of new treatments. To ensure the best functional recovery, regenerative therapy may require the application of a combination approach that includes cell replacement, trophic support, and neural protection. Here we review the current state of our knowledge about endogenous adult and exogenous neural stem/progenitor cells as potential therapeutic agents for central nervous system injuries.

Abstract C56: Characterization of hz515H7, a novel humanized anti-CXCR4 antibody: In vitro efficacy on CXCR4-associated signaling pathways and in vivo antitumor activity.

Abstract C56: Characterization of hz515H7, a novel humanized anti-CXCR4 antibody: In vitro efficacy on CXCR4-associated signaling pathways and in vivo antitumor activity.

Analysis of Two Major Intracellular Phospholipases A2 (PLA2) in Mast Cells Reveals Crucial Contribution of Cytosolic PLA2α, Not Ca2+-independent PLA2β, to Lipid Mobilization in Proximal Mast Cells and Distal Fibroblasts

Mast cells release a variety of mediators, including arachidonic acid (AA) metabolites, to regulate allergy, inflammation, and host defense, and their differentiation and maturation within extravascular microenvironments depend on the stromal cytokine stem cell factor. Mouse mast cells express two major intracellular phospholipases A(2) (PLA(2)s), namely group IVA cytosolic PLA(2) (cPLA(2)α) and group VIA Ca(2+)-independent PLA(2) (iPLA(2)β), and the role of cPLA(2)α in eicosanoid synthesis by mast cells has been well documented. Lipidomic analyses of mouse bone marrow-derived mast cells (BMMCs) lacking cPLA(2)α (Pla2g4a(-/-)) or iPLA(2)β (Pla2g6(-/-)) revealed that phospholipids with AA were selectively hydrolyzed by cPLA(2)α, not by iPLA(2)β, during FcεRI-mediated activation and even during fibroblast-dependent maturation. Neither FcεRI-dependent effector functions nor maturation-driven phospholipid remodeling was impaired in Pla2g6(-/-) BMMCs. Although BMMCs did not produce prostaglandin E(2) (PGE(2)), the AA released by cPLA(2)α from BMMCs during maturation was converted to PGE(2) by microsomal PGE synthase-1 (mPGES-1) in cocultured fibroblasts, and accordingly, Pla2g4a(-/-) BMMCs promoted microenvironmental PGE(2) synthesis less efficiently than wild-type BMMCs both in vitro and in vivo. Mice deficient in mPGES-1 (Ptges(-/-)) had an augmented local anaphylactic response. These results suggest that cPLA(2)α in mast cells is functionally coupled, through the AA transfer mechanism, with stromal mPGES-1 to provide anti-anaphylactic PGE(2). Although iPLA(2)β is partially responsible for PGE(2) production by macrophages and dendritic cells, it is dispensable for mast cell maturation and function.

Bioimaging analysis of nuclear factor‐κB activity in Philadelphia chromosome‐positive acute lymphoblastic leukemia cells reveals its synergistic upregulation by tumor necrosis factor‐α‐stimulated changes to the microenvironment

To gain an insight into the microenvironmental regulation of nuclear factor (NF)-κB activity in the progression of leukemia, we established a bioluminescent imaging model of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) cells transduced with a NF-κB/luciferase (Luc) reporter and cocultured with murine stromal cells and cytokines. Stromal cells alone did not augment Luc activity, taken as an index of NF-κB, but Luc activity was synergistically upregulated by the combination of stromal cells and tumor necrosis factor (TNF)-α. Dehydroxymethylepoxyquinomicin (DHMEQ), a specific inhibitor of NF-κB DNA binding, rapidly induced the apoptosis of Ph+ALL cells, indicating that NF-κB is necessary for the growth and survival of these cells. However, the DHMEQ-induced suppression of NF-κB activity and the apoptosis of leukemia cells were attenuated by the presence of stromal cells and TNF-α. In NOD-SCID mice transplanted with NF-κB/Luc reporter-containing Ph+ALL cell lines and monitored periodically during the progression of the leukemia, murine TNF-α was significantly expressed in lesions in which the leukemia cells emitted a significant NF-κB signal. These results support the notion that TNF-α also triggers microenvironmental upregulation of NF-κB activity in vivo. Collectively, the results indicated that TNF-α-stimulated microenvironment may contribute to the survival and progression of Ph+ALL cells through the synergistic upregulation of NF-κB activity.

The effects of targeting stromal and tumor cell platelet-derived growth factor receptor (PDGFR) in non-small cell lung cancer (NSCLC).

10533 Background: Platelet-derived growth factor receptor (PDGFR) has emerged as a potential target for cancer therapy. In non-small cell lung cancer (NSCLC), PDGFR is expressed frequently by stromal cells in the tumor microenvironment and, in a subset of tumors, by cancer cells themselves. However, most recent research has focused exclusively on cancer cell PDGFR, overlooking the effect of PDGFR inhibition in the tumor stroma. Methods: To evaluate the effects of targeting stromal PDGFR, which has roles in fibroblast activation, local tissue invasion, modulation of tumor interstitial pressure, and angiogenesis, we capitalized on the xenograft model and the availability of species-specific anti-PDGFRα antibodies. In this model, IMC 3G3, a fully human anti-human PDGFRα monoclonal antibody, inhibits cancer cell PDGFRα; IMC 1E10, a fully human anti-mouse PDGFRα monoclonal antibody, inhibits stromal PDGFRα. Results: We confirmed species specificity of IMC 3G3 and IMC 1E10 via (1) patterns of immunoreactivity with human PDGFR-positive cancer cells and mouse PDGFR-positive fibroblasts, (2) inhibition of murine fibroblast PDGFRα activation by IMC 1E10 but not by IMC 3G3, and (3) in vitro inhibition of proliferation of human PDGFR-positive cancer cells by IMC 3G3 but not by IMC 1E10. As expected, only rare NSCLC featuring high-level PDGFRα expression responded to inhibition of cancer cell PDGFRα. However, in vivo, stromal PDGFRα targeting inhibited the growth of PDGFRα-negative NSCLC xenografts and enhanced the effect of chemotherapy. Conclusions: IMC 3G3 and IMC 1E10 exhibit species-specific PDGFR targeting, allowing individual evaluation of tumor- and stromal PDGFRa inhibition. Stromal PDGFR inhibition may represent a means for enhancing control of lung cancer growth in some patients, independent of tumor cell PDGFR expression. Because PDGFR is widely expressed in NSCLC stromal cells, these findings suggest that stromal PDGFR inhibition could benefit a large proportion of these patients.