Giovanna Tosato

NCI-Frederick, Фредерик, Maryland, United States

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Publications (221)1644.69 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Angiogenesis produces primitive vascular networks that need pruning to yield hierarchically organized and functional vessels. Despite the critical importance of vessel pruning to vessel patterning and function, the mechanisms regulating this process are not clear. Here we show that EphrinB2, a well-known player in angiogenesis, is an essential regulator of endothelial cell death and vessel pruning. This regulation depends upon phosphotyrosine-EphrinB2 signalling repressing c-jun N-terminal kinase 3 activity via STAT1. JNK3 activation causes endothelial cell death. In the absence of JNK3, hyaloid vessel physiological pruning is impaired, associated with abnormal persistence of hyaloid vessels, defective retinal vasculature and microphthalmia. This syndrome closely resembles human persistent hyperplastic primary vitreus (PHPV), attributed to failed involution of hyaloid vessels. Our results provide evidence that EphrinB2/STAT1/JNK3 signalling is essential for vessel pruning, and that defects in this pathway may contribute to PHPV.
    Nature Communications 03/2015; 6:6576. DOI:10.1038/ncomms7576 · 10.74 Impact Factor
  • Shuhei Sakakibara, Giovanna Tosato
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    ABSTRACT: Kaposi's sarcoma-associated herpesvirus (KSHV, also named Human herpesvirus 8 HHV-8) is the cause of Kaposi sarcoma (KS), the most common malignancy in HIV-infected individuals worldwide, primary effusion lymphoma (PEL) and multicentric Castleman disease (MCD). KSHV is a double-stranded DNA virus that encodes several homologues of cellular proteins. The structural similarity between viral and host proteins explains why some viral homologues function as their host counterparts, but sometimes at unusual anatomical sites and inappropriate times. In other cases, structural modification in the viral proteins can suppress or override the function of the host homologue, contributing to KSHV-related diseases. For example, viral IL-6 (vIL-6) is sufficiently different from human IL-6 to activate gp130 signaling independent of the a subunit. As a consequence, vIL-6 can activate many cell types that are unresponsive to cellular IL-6, contributing to MCD disease manifestations. Here, we discuss the molecular biology of KSHV homologues of cellular products as conduits of virus/host interaction with a focus on identifying new strategies for therapy of KS and other KSHV-related diseases.
    Viruses 09/2014; 6(9):3472-3486. DOI:10.3390/v6093472 · 3.28 Impact Factor
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    Hidetaka Ohnuki, Giovanna Tosato
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    ABSTRACT: Cell signals integral to the tumor microenvironment influence cancer progression. Tumor-associated myeloid cells secrete pro-tumorigenic agents including, but not limited to, the potent cytokine transforming growth factor β (TGFβ). We have discovered a network of extrinsic signals including delta-like 4 (Dll4), Notch and TGFβ, linking malignant cells and tumor-infiltrating myeloid cells, a nexus portending a clinically-relevant anticancer treatment.
    OncoImmunology 05/2014; 3(5):e29029. DOI:10.4161/onci.29029 · 6.28 Impact Factor
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    ABSTRACT: Myeloid cells that orchestrate malignant progression in the tumor microenvironment offer targets for a generalized strategy to attack solid tumors. Through an analysis of tumor microenvironments, we explored an experimental model of lung cancer that uncovered a network of Dll4/Notch/TGF-β1 signals that links myeloid cells to cancer progression. Myeloid cells attracted to the tumor microenvironment by the tumor-derived cytokines CCL2 and M-CSF expressed increased levels of the Notch ligand Dll4, thereby activating Notch signaling in the tumor cells and amplifying intrinsic Notch activation there. Heightened Dll4/Notch signaling in tumor cells magnified TGF-β-induced pSMAD2/3 signaling and was required to sustain TGF-β-induced tumor cell growth. Conversely, Notch blockade reduced TGF-β signaling and limited lung carcinoma tumor progression. Corroborating these findings, interrogating RNAseq results from tumor and adjacent normal tissue in clinical specimens of human head and neck squamous carcinoma we found evidence that TGF-β/Notch crosstalk contributed to progression. In summary, the myeloid cell-carcinoma signaling network we describe uncovers novel mechanistic links between the tumor microenvironment and tumor growth, highlighting new opportunities to target tumors where this network is active.
    Cancer Research 02/2014; 74(7). DOI:10.1158/0008-5472.CAN-13-3118 · 9.28 Impact Factor
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    ABSTRACT: The Eph receptor tyrosine kinases mediate juxtacrine signals by interacting "in trans" with ligands anchored to the surface of neighboring cells via a GPI-anchor (ephrin-As) or a transmembrane segment (ephrin-Bs), which leads to receptor clustering and increased kinase activity. Additionally, soluble forms of the ephrin-A ligands released from the cell surface by matrix metalloproteases can also activate EphA receptor signaling. Besides these trans interactions, recent studies have revealed that Eph receptors and ephrins coexpressed in neurons can also engage in lateral "cis" associations that attenuate receptor activation by ephrins in trans with critical functional consequences. Despite the importance of the Eph/ephrin system in tumorigenesis, Eph receptor-ephrin cis interactions have not been previously investigated in cancer cells. Here we show that in cancer cells, coexpressed ephrin-A3 can inhibit the ability of EphA2 and EphA3 to bind ephrins in trans and become activated, while ephrin-B2 can inhibit not only EphB4 but also EphA3. The cis inhibition of EphA3 by ephrin-B2 implies that in some cases ephrins that cannot activate a particular Eph receptor in trans can nevertheless inhibit its signaling ability through cis association. We also found that an EphA3 mutation identified in lung cancer enhances cis interaction with ephrin-A3. These results suggest a novel mechanism that may contribute to cancer pathogenesis by attenuating the tumor suppressing effects of Eph receptor signaling pathways activated by ephrins in trans.
    PLoS ONE 11/2013; 8(11):e81445. DOI:10.1371/journal.pone.0081445 · 3.53 Impact Factor
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    ABSTRACT: Kaposi sarcoma herpesvirus (KSHV)-associated multicentric Castleman disease (MCD) is a polyclonal B-cell lymphoproliferative disorder. Human IL-6 and a KSHV-encoded homolog, viral IL-6, have been hypothesized to contribute to its pathogenesis but their relative contributions to disease activity is not well understood. We prospectively characterized KSHV viral load (VL), viral (v) and human (h) IL-6, and other cytokines during KSHV-MCD flare and remission in 21 patients with 34 flares and 20 remissions. KSHV-VL, vIL-6, hIL-6 , IL-10, and to a lesser extent TNF-α, and IL-1β were each elevated during initial flares compared with remission. Flares fell into three distinct IL-6 profiles: those associated with elevations of vIL-6 only (2 flares, 6%), hIL-6 elevations only (17 flares, 50%), and elevations in both hIL-6 and vIL-6 (13 flares, 38%). Compared with hIL-6-only flares, flares with elevated hIL-6 plus vIL-6 exhibited higher CRP (P=0.0009); worse hyponatremia (P=0.02); higher KSHV VL (P=0.016) and higher IL-10 (P=0.012). This analysis shows vIL-6 and hIL-6 can independently or together lead KSHV-MCD flares, and suggests that vIL-6 and hIL-6 may jointly contribute to disease severity. These findings have implications for the development of novel KSHV-MCD therapies targeting IL-6 and its downstream signaling. This study was registered at as NCT099073.
    Blood 10/2013; 122(26). DOI:10.1182/blood-2013-08-519959 · 10.43 Impact Factor
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    ABSTRACT: Multicentric Castleman Disease (MCD) is a distinct lymphoproliferative disorder characterized by inflammatory symptoms, lymphadenopathy, splenomegaly and cytopenia. Kaposi sarcoma-associated herpesvirus (KSHV), also called human herpesvirus-8 (HHV-8), is the cause of virtually all cases of MCD occurring in HIV-infected patients. MCD lesions characteristically contain HHV-8-infected polyclonal IgMλ plasmablasts. A high frequency of HHV-8-related non-Hodgkin lymphoma has been reported in these patients. We now report on three patients who presented with severe symptoms of MCD, extreme splenomegaly and rapid expansion of B-cell lymphocytosis (44-81%) attributable to circulating HHV-8 positive plasmablasts. The circulating plasmablastic cells shared the phenotype (IgMλ, CD19+, CD20-, CD138-) of HHV-8-infected cells from MCD lesions, mimicking the leukemic phase of large B-cell lymphoma occurring in HHV-8-related MCD, These patients displayed a very high HHV-8 viral load in blood (>7 logs HHV-8 DNA copies/ml) and high levels of serum vIL-6, the viral homolog of human interleukin 6. Serum IL-6 and IL-10 were also abnormally elevated. HHV-8-infected cells were demonstrated by immunoglobulin gene rearrangement analysis, to be polyclonal and likely represent an expansion of HHV-8-infected cells similar to those found in MCD lesions. Thus, the spectrum of HHV-8-related plasmablastic lymphoproliferative disorders in HIV-infected patients, is expanded to include HHV-8+ polyclonal IgMλ B-cell lymphocytosis. At onset, this lymphoproliferative disorder may mimick plasmablastic leukemia/lymphoma. Recognizing this unusual complication may have important implications in treatment decision avoiding unnecessary toxicity to the patients. This article is protected by copyright. All rights reserved.
    European Journal Of Haematology 09/2013; 91(6). DOI:10.1111/ejh.12191 · 2.41 Impact Factor
  • Kan Jiang, Hyeongil Kwak, Giovanna Tosato
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    ABSTRACT: Although Vascular Endothelial Growth Factor (VEGF)-targeted therapies have shown efficacy in the treatment of certain advanced cancers, benefits to patients have been modest, which is attributed to tumor resistance to VEGF neutralization. Recent efforts to identify new targets to inhibit tumor angiogenesis have identified Bv8 (prokineticin 2), a myeloid cell-derived protein that promotes endothelial cell growth and tumor angiogenesis, but many mechanistic aspects of the pro-tumorigenic function of Bv8 are unclear. Here we demonstrate that CD11b+, Ly6C+, Ly6G+ granulocytes are the predominant cell source of Bv8 expression in bone marrow, spleen and in tumor tissues. Using granulocyte-deficient Growth factor independence-1 (Gfi1)-null mutant mice and normal littermates, we found that EL4 lymphoma tumors grow significantly larger in the granulocyte and Bv8-deficient mutant mice in comparison to the normal mice that display abundant tumor-associated granulocytes and Bv8 expression. Conversely, Lewis lung carcinoma (LLC-1) tumors grew to a significantly greater size in the normal mice in comparison to the Gfi1-null mice, but normal granulocyte tumor infiltration was modest. Quantitative analysis of tissue vascularization showed that EL4 and LLC-1 tumors from normal and Gfi1-mutant mice are similarly vascularized. These results confirm the critical contribution of the tumor microenvironment in determining the rate of tumor progression independently of tumor angiogenesis, and reveal some of the complexities of granulocyte and Bv8 functions in modulating tumor growth.
    01/2013; 5(1):82. DOI:10.7759/cureus.82
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    ABSTRACT: Formation of new vessels during development and in the mature mammal generally proceeds through angiogenesis. Although a variety of molecules and signaling pathways are known to underlie endothelial cell sprouting and remodeling during angiogenesis, many aspects of this complex process remain unexplained. Here we show that the transmembrane semaphorin6A (Sema6A) is expressed in endothelial cells, and regulates endothelial cell survival and growth by modulating the expression and signaling of VEGFR2, which is known to maintain endothelial cell viability by autocrine VEGFR signaling. The silencing of Sema6A in primary endothelial cells promotes cell death that is not rescued by exogenous VEGF-A or FGF2, attributable to the loss of pro-survival signaling from endogenous VEGF. Analyses of mouse tissues demonstrate that Sema6A is expressed in angiogenic and remodeling vessels. Mice with null mutations of Sema6A exhibit significant defects in hyaloid vessels complexity associated with increased endothelial cell death, and in retinal vessels development that is abnormally reduced. Adult Sema6A-null mice exhibit reduced tumor, Matrigel and choroidal angiogenesis compared to controls. Sema6A plays important roles in development of the nervous system. Here we show that it also regulates vascular development and adult angiogenesis.
    Blood 11/2012; 120(19). DOI:10.1182/blood-2012-02-410076 · 10.43 Impact Factor
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    ABSTRACT: Kaposi's sarcoma-associated herpesvirus (KSHV) K13/vFLIP (viral Flice-inhibitory protein) induces transcription of numerous genes through NF-κB activation, including pro-inflammatory cytokines, which contribute to the pathogenesis of Kaposi's sarcoma (KS). In this study, we report that KSHV vFLIP induces the expression of the NF-κB regulatory proteins A20, ABIN-1 and ABIN-3 (A20-binding NF-κB inhibitors) in primary human endothelial cells, and that KS spindle cells express A20 in KS tissue. In reporter assays, A20 strongly impaired vFLIP-induced NF-κB activation in 293T cells, but ABIN-1 and ABIN-3 did not. Mutational analysis established that the C-terminal domain (residues 427-790) is critical for A20 modulation of NF-κB, but the ubiquitin-editing OTU (ovarian tumor) domain is not. In functional assays, A20 inhibited vFLIP-induced expression of the chemokine IP-10, reduced vFLIP-induced cell proliferation and increased IKK1 protein levels. Thus, we demonstrate that A20 negatively regulates NF-κB activation directly induced by KSHV vFLIP. By attenuating excessive and prolonged vFLIP-induced NF-κB activation that could be harmful to KSHV-infected cells, A20 likely has an important role in the pathogenesis of KSHV-associated diseases, in which vFLIP is expressed.Oncogene advance online publication, 23 April 2012; doi:10.1038/onc.2012.145.
    Oncogene 04/2012; DOI:10.1038/onc.2012.145 · 8.56 Impact Factor
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    ABSTRACT: Human herpes virus 8 (HHV-8) or Kaposi sarcoma-associated herpes virus is the etiologic agent of Kaposi sarcoma, primary effusion lymphoma, and plasma cell-type multicentric Castleman disease (MCD). HHV-8 encodes a viral homolog of human IL-6, called viral IL-6 (vIL-6), which does not require the cellular IL-6 receptor for binding to the ubiquitously expressed gp130 receptor subunit and subsequent JAK-STAT signaling. Thus, in contrast to IL-6, vIL-6 can stimulate virtually all cells in the body. To elucidate the mechanism by which vIL-6 drives human diseases, we generated transgenic mice that constitutively express vIL-6 under control of the MHC class I promoter. The mice were found to exhibit vIL-6 serum levels comparable with those observed in HHV-8-infected patients, to contain elevated amounts of phosphorylated STAT3 in spleen and lymph nodes, where vIL-6 was produced, and to spontaneously develop key features of human plasma cell-type MCD, including splenomegaly, multifocal lymphadenopathy, hypergammaglobulinemia, and plasmacytosis. Transfer of the vIL-6 transgene onto an IL-6-deficient genetic background abrogated MCD-like phenotypes, indicating that endogenous mouse IL-6 is a crucial cofactor in the natural history of the disease. Our results in mice suggest that human IL-6 plays an important role in the pathogenesis of HHV-8-associated MCD.
    Blood 04/2012; 119(22):5173-81. DOI:10.1182/blood-2011-09-377705 · 10.43 Impact Factor
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    ABSTRACT: Endothelial-to-mesenchymal transition (EndMT) is now widely considered a pivotal contributor to cancer progression. In this study, we show that the Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) is a sufficient cause of EndMT, potentially helping to explain the aggressiveness of KS that occurs commonly in AIDS patients. Upon KSHV infection, primary dermal microvascular endothelial cells lost expression of endothelial markers and acquired expression of mesenchymal markers, displaying new invasive and migratory properties along with increased survival. KSHV activated Notch-induced transcription factors Slug and ZEB1, and canonical Notch signaling was required for KSHV-induced EndMT. In contrast, KSHV did not utilize the TGFβ signaling pathway, which has also been linked to EndMT. Within KS lesions, KSHV-infected spindle cells displayed features compatible with KSHV-induced EndMT including a complex phenotype of endothelial and mesenchymal properties, Notch activity, and nuclear ZEB1 expression. Our results show that KSHV engages the EndMT program to increase the invasiveness and survival of infected endothelial cells, traits that likely contribute to viral persistence and malignant progression. One important implication of our findings is that therapeutic approaches to disrupt the Notch pathway may offer novel approaches for KS treatment.
    Cancer Research 03/2012; 72(5):1157-69. DOI:10.1158/0008-5472.CAN-11-3067 · 9.28 Impact Factor
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    ABSTRACT: Mobilization of hematopoietic stem/progenitor cells from the bone marrow to the peripheral blood by granulocyte colony-stimulating factor is the primary means to acquire stem cell grafts for hematopoietic cell transplantation. Since hematopoietic stem/progenitor cells represent a minority of all blood cells mobilized by granulocyte colony-stimulating factor, the underlying mechanisms need to be understood in order to develop selective drugs. We analyzed phenotypic, biochemical and genetic changes in bone marrow cell populations from granulocyte colony-stimulating factor-mobilized and control mice, and linked such changes to effective mobilization of hematopoietic stem/progenitor cells. We show that granulocyte colony-stimulating factor indirectly reduces expression of surface vascular cell adhesion molecule 1 on bone marrow hematopoietic stem/progenitor cells, stromal cells and endothelial cells by promoting the accumulation of microRNA-126 (miR126)-containing microvescicles in the bone marrow extracellular compartment. We found that hematopoietic stem/progenitor cells, stromal cells and endothelial cells readily incorporate these miR126-loaded microvescicles, and that miR126 represses vascular cell adhesion molecule 1 expression on bone marrow hematopoietic stem/progenitor cells, stromal cells and endothelial cells. In line with this, miR126-null mice displayed a reduced mobilization response to granulocyte colony-stimulating factor. Our results implicate miR126 in the regulation of hematopoietic stem/progenitor cell trafficking between the bone marrow and peripheral sites, clarify the role of vascular cell adhesion molecule 1 in granulocyte colony-stimulating factor-mediated mobilization, and have important implications for improved approaches to selective mobilization of hematopoietic stem/progenitor cells.
    Haematologica 01/2012; 97(6):818-26. DOI:10.3324/haematol.2011.056945 · 5.87 Impact Factor
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    ABSTRACT: KSHV, also called human herpesvirus-8, is the cause of a form of MCD called KSHV-MCD. KSHV-MCD is clinically similar to idiopathic MCD; in both, the clinical picture is characterized by fevers, weight loss, fatigue, edema, lymphadenopathy, splenomegaly, cytopenias, low albumin, and elevated C-reactive protein (CRP). The diagnosis of both is based on pathologic findings in lymph nodes, including the presence of plasmablasts. In idiopathic MCD, systemic manifestations are caused by overproduction of human interleukin-6 (hIL-6) and other cytokines by plasmablasts in affected lymphoid organs. KSHV encodes a mimic of hIL-6 called viral IL-6 (vIL-6). In KSHV-MCD, a subset of the lymph node plasmablasts are infected with KSHV, and a subset of these express vIL-6 and other lytic KSHV genes. We have studied 34 flares of KSHV-MCD and found that flares were often associated with an increase in hIL-6, vIL-6, or both; in 2 patients neither cytokine was elevated at the flare onset. Other elevated cytokines included IL-10, tumor necrosis factor alpha (TNF-[alpha]), and IL-1[beta]. Flares were also associated with an elevated viral load of KSHV. We also identified 6 patients with symptoms of KSHV-MCD, elevated KSHV viral load, and elevated vIL-6 but without pathologic findings of MCD; we have called this condition KSHV-associated inflammatory cytokine syndrome (KICS). KSHV-MCD is fatal if not treated. Based on the observation that zidovudine (AZT) and ganciclovir are activated to toxic moieties by KSHV lytic enzymes, we investigated a regimen of high-dose AZT and valganciclovir, a pro-drug of ganciclovir, in KSHV-MCD and showed that it had activity. Other information on the pathogenesis and treatment of these conditions will be presented.
    JAIDS Journal of Acquired Immune Deficiency Syndromes 01/2012; 59:62. DOI:10.1097/01.qai.0000413768.83222.c5 · 4.39 Impact Factor
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    Ombretta Salvucci, Giovanna Tosato
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    ABSTRACT: Eph receptor tyrosine kinases and their Ephrin ligands represent an important signaling system with widespread roles in cell physiology and disease. Receptors and ligands in this family are anchored to the cell surface; thus Eph/Ephrin interactions mainly occur at sites of cell-to-cell contact. EphB4 and EphrinB2 are the Eph/Ephrin molecules that play essential roles in vascular development and postnatal angiogenesis. Analysis of expression patterns and function has linked EphB4/EphrinB2 to endothelial cell growth, survival, migration, assembly, and angiogenesis. Signaling from these molecules is complex, with the potential for being bidirectional, emanating both from the Eph receptors (forward signaling) and from the Ephrin ligands (reverse signaling). In this review, we describe recent advances on the roles of EphB/EphrinB protein family in endothelial cell function and outline potential approaches to inhibit pathological angiogenesis based on this understanding.
    Advances in Cancer Research 01/2012; 114:21-57. DOI:10.1016/B978-0-12-386503-8.00002-8 · 4.26 Impact Factor
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    ABSTRACT: The EphB4 receptor tyrosine kinase together with its preferred ligand, ephrin-B2, regulates a variety of physiological and pathological processes, including tumor progression, pathological forms of angiogenesis, cardiomyocyte differentiation and bone remodeling. We previously reported the identification of TNYL-RAW, a 15 amino acid-long peptide that binds to the ephrin-binding pocked of EphB4 with low nanomolar affinity and inhibits ephrin-B2 binding. Although ephrin-B2 interacts promiscuously with all the EphB receptors, the TNYL-RAW peptide is remarkably selective and only binds to EphB4. Therefore, this peptide is a useful tool for studying the biological functions of EphB4 and for imaging EphB4-expressing tumors. Furthermore, TNYL-RAW could be useful for treating pathologies involving EphB4-ephrin-B2 interaction. However, the peptide has a very short half-life in cell culture and in the mouse blood circulation due to proteolytic degradation and clearance by the kidneys and reticuloendothelial system. To overcome these limitations, we have modified TNYL-RAW by fusion with the Fc portion of human IgG1, complexation with streptavidin or covalent coupling to a 40 KDa branched polyethylene glycol (PEG) polymer. These modified forms of TNYL-RAW all have greatly increased stability in cell culture, while retaining high binding affinity for EphB4. Furthermore, PEGylation most effectively increases peptide half-life in vivo. Consistent with increased stability, submicromolar concentrations of PEGylated TNYL-RAW effectively impair EphB4 activation by ephrin-B2 in cultured B16 melanoma cells as well as capillary-like tube formation and capillary sprouting in co-cultures of endothelial and epicardial mesothelial cells. Therefore, PEGylated TNYL-RAW may be useful for inhibiting pathological forms of angiogenesis through a novel mechanism involving disruption of EphB4-ephrin-B2 interactions between endothelial cells and supporting perivascular mesenchymal cells. Furthermore, the PEGylated peptide is suitable for other cell culture and in vivo applications requiring prolonged EphB4 receptor targeting.
    PLoS ONE 12/2011; 6(12):e28611. DOI:10.1371/journal.pone.0028611 · 3.53 Impact Factor
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    Shuhei Sakakibara, Giovanna Tosato
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    ABSTRACT: Viral interleukin-6 (vIL-6) is a product of Kaposi's sarcoma-associated herpesvirus (KSHV) expressed in latently infected cells and to a higher degree during viral replication. A distinctive feature of vIL-6 is the ability to directly bind and activate gp130 signaling in the absence of other receptor subunits. Secretion of vIL-6 is generally poor, but vIL-6 can activate gp130 from inside the cell. Due to the wide cell distribution of gp130, vIL-6 has the potential to induce a wide range of biological effects. Expression of vIL-6 is variable in KSHV-associated Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), multicentric Castleman's disease (MCD), and in a newly described MCD-like systemic inflammatory syndrome observed in human immunodeficiency virus-positive patients. PEL effusions usually contain vIL-6 at high concentrations; since vIL-6 induces vascular endothelial growth factor, vIL-6 likely contributes to vascular permeability and formation of PEL effusions. Lymph nodes affected with MCD contain vIL-6-positive cells, and vIL-6 levels rise in conjunction with flares of the disease and likely contribute to symptoms of inflammation. The development of vIL-6 inhibitors is a potentially important advance in the treatment of KSHV-associated malignancies where vIL-6 is expressed.
    Journal of interferon & cytokine research: the official journal of the International Society for Interferon and Cytokine Research 07/2011; 31(11):791-801. DOI:10.1089/jir.2011.0043 · 3.90 Impact Factor
  • Cancer Research 07/2011; 71(8 Supplement):3469-3469. DOI:10.1158/1538-7445.AM2011-3469 · 9.28 Impact Factor
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    ABSTRACT: A precise identification of adult human hemangioblast is still lacking. To identify circulating precursors having the developmental potential of the hemangioblast, we established a new ex vivo long-term culture model supporting the differentiation of both hematopoietic and endothelial cell lineages. We identified from peripheral blood a population lacking the expression of CD34, lineage markers, CD45 and CD133 (CD34⁻Lin⁻CD45⁻CD133⁻ cells), endowed with the ability to differentiate after a 6-week culture into both hematopoietic and endothelial lineages. The bilineage potential of CD34⁻Lin⁻CD45⁻CD133⁻ cells was determined at the single-cell level in vitro and was confirmed by transplantation into NOD/SCID mice. In vivo, CD34⁻Lin⁻CD45⁻CD133⁻ cells showed the ability to reconstitute hematopoietic tissue and to generate functional endothelial cells that contribute to new vessel formation during tumor angiogenesis. Molecular characterization of CD34⁻Lin⁻D45⁻CD133⁻ cells unveiled a stem cell profile compatible with both hematopoietic and endothelial potentials, characterized by the expression of c-Kit and CXCR4 as well as EphB4, EphB2, and ephrinB2. Further molecular and functional characterization of CD34⁻Lin⁻CD45⁻CD133⁻ cells will help dissect their physiologic role in blood and blood vessel maintenance and repair in adult life.
    Blood 06/2011; 118(8):2105-15. DOI:10.1182/blood-2010-10-316596 · 10.43 Impact Factor
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    ABSTRACT: Kaposi sarcoma herpesvirus (KSHV)-associated multicentric Castleman disease (MCD) is a lymphoproliferative disorder most commonly observed in HIV-infected patients. It is characterized by KSHV-infected plasmablasts that frequently express lytic genes. Patients manifest inflammatory symptoms attributed to overproduction of KSHV viral IL-6, human IL-6, and human IL-6. There is no standard therapy and no established response criteria. We investigated an approach targeting 2 KSHV lytic genes, ORF36 and ORF21, the protein of which, respectively, phosphorylate ganciclovir and zidovudine to toxic moieties. In a pilot study, 14 HIV-infected patients with symptomatic KSHV-MCD received high-dose zidovudine (600 mg orally every 6 hours) and the oral prodrug, valganciclovir (900 mg orally every 12 hours). Responses were evaluated using new response criteria. A total of 86% of patients attained major clinical responses and 50% attained major biochemical responses. Median progression-free survival was 6 months. With 43 months of median follow-up, overall survival was 86% at 12 months and beyond. At the time of best response, the patients showed significant improvements in C-reactive protein, albumin, platelets, human IL-6, IL-10, and KSHV viral load. The most common toxicities were hematologic. These observations provide evidence that therapy designed to target cells with lytic KSHV replication has activity in KSHV-MCD. This trial was registered at as #NCT00099073.
    Blood 04/2011; 117(26):6977-86. DOI:10.1182/blood-2010-11-317610 · 10.43 Impact Factor

Publication Stats

10k Citations
1,644.69 Total Impact Points


  • 2000–2014
    • NCI-Frederick
      Фредерик, Maryland, United States
  • 1994–2013
    • National Cancer Institute (USA)
      • • HIV and AIDS Malignancy Branch
      • • Laboratory of Cellular Oncology
      • • Experimental Transplantation and Immunology Branch
      • • Laboratory of Pathology
      Maryland, United States
    • Georgetown University
      Washington, Washington, D.C., United States
  • 1979–2013
    • National Institutes of Health
      • • Laboratory of Cellular Oncology
      • • Branch of Experimental Transplantation and Immunology
      • • Basic Research Laboratory
      • • Branch of HIV and AIDS Malignancy
      • • Branch of Medical Genetics
      • • Laboratory of Pathology
      • • Laboratory of Immunology
      • • Branch of Metabolism
      • • Branch of Pediatric Oncology
      베서스다, Maryland, United States
  • 2006–2008
    • University of Oxford
      Oxford, England, United Kingdom
  • 1988–2008
    • U.S. Food and Drug Administration
      • Center for Biologics Evaluation and Research
      Washington, Washington, D.C., United States
    • The Rockefeller University
      New York, New York, United States
    • National Institute of Child Health and Human Development
      베서스다, Maryland, United States
  • 2007
    • Astellas Pharmaceutical
      Northbrook, Illinois, Japan
  • 2004
    • Translational Genomics Research Institute
      Phoenix, Arizona, United States
    • Council for Chemical Research
      베서스다, Maryland, United States
  • 2001
    • American Society of Hematology
      American Fork, Utah, United States
  • 1999
    • Toyama Medical and Pharmaceutical University
      Тояма, Toyama, Japan
  • 1997
    • Kochi Medical School
      Kôti, Kōchi, Japan
  • 1995
    • Children's National Medical Center
      Washington, Washington, D.C., United States
  • 1986–1991
    • Walter Reed Army Institute of Research
      Silver Spring, Maryland, United States
  • 1985
    • National Institute of Allergy and Infectious Diseases
      Maryland, United States