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Malignant progression and blockade of angiogenesis in a murine transgenic model of neuroblastoma.

ABSTRACT: Targeted expression of MYCN to the neural crest [under control of the rat tyrosine hydroxylase (TH) promoter] causes neuroblastoma in transgenic mice (TH-MYCN) and is a well-established model for this disease. Because high levels of MYCN are associated with enhanced tumor angiogenesis and poor clinical outcome in neuroblastoma, we serially characterized malignant progression, angiogenesis, and sensitivity to angiogenic blockade in tumors from these animals. Tumor cells were proliferative, secreted high levels of the angiogenic ligand vascular endothelial growth factor (VEGF), and recruited a complex vasculature expressing the angiogenic markers VEGF-R2, alpha-SMA, and matrix metalloproteinases MMP-2 and MMP-9, all of which are also expressed in human disease. Treatment of established murine tumors with the angiogenesis inhibitor TNP-470 caused near-complete ablation, with reduced proliferation, enhanced apoptosis, and vasculature disruption. Because TNP-470 has been associated with neurotoxicity, we tested the recently described water-soluble HPMA copolymer-TNP-470 conjugate (caplostatin), which showed comparable efficacy and was well tolerated without weight loss or neurotoxicity as measured by rotarod testing. This study highlights the importance of angiogenesis inhibition in a spontaneous murine tumor with native tumor-microenvironment interactions, validates the use of mice transgenic for TH-MYCN as a model for therapy in this common pediatric tumor, and supports further clinical development of caplostatin as an antiangiogenic therapy in childhood neuroblastoma.

SUBMITTER: Chesler L

PROVIDER: S-EPMC2921769 | biostudies-literature | 2007 Oct

REPOSITORIES: biostudies-literature

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Malignant progression and blockade of angiogenesis in a murine transgenic model of neuroblastoma.

Chesler Louis L Goldenberg David D DD Seales Isha T IT Satchi-Fainaro Ronit R Grimmer Matt M Collins Rodney R Struett Chris C Nguyen Kim N KN Kim Grace G Tihan Tarik T Bao Yun Y Brekken Rolf A RA Bergers Gabriele G Folkman Judah J Weiss William A WA

Cancer research 20071001 19

Targeted expression of MYCN to the neural crest [under control of the rat tyrosine hydroxylase (TH) promoter] causes neuroblastoma in transgenic mice (TH-MYCN) and is a well-established model for this disease. Because high levels of MYCN are associated with enhanced tumor angiogenesis and poor clinical outcome in neuroblastoma, we serially characterized malignant progression, angiogenesis, and sensitivity to angiogenic blockade in tumors from these animals. Tumor cells were proliferative, secret ...[more]

PMID: 17909053

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Project description:BackgroundThe induction of tumor angiogenesis, a pathologic process critical for tumor progression, is mediated by multiple regulatory factors released by tumor and host cells. We investigated the role of the hematopoietic cytokine erythropoietin as an angiogenic factor that modulates tumor progression.Methodology/principal findingsFluorescently-labeled rodent mammary carcinoma cells were injected into dorsal skin-fold window chambers in mice, an angiogenesis model that allows direct, non-invasive, serial visualization and real-time assessment of tumor cells and neovascularization simultaneously using intravital microscopy and computerized image analysis during the initial stages of tumorigenesis. Erythropoietin or its antagonist proteins were co-injected with tumor cells into window chambers. In vivo growth of cells engineered to stably express a constitutively active erythropoietin receptor EPOR-R129C or the erythropoietin antagonist R103A-EPO were analyzed in window chambers and in the mammary fat pads of athymic nude mice. Co-injection of erythropoietin with tumor cells or expression of EPOR-R129C in tumor cells significantly stimulated tumor neovascularization and growth in window chambers. Co-injection of erythropoietin antagonist proteins (soluble EPOR or anti-EPO antibody) with tumor cells or stable expression of antagonist R103A-EPO protein secreted from tumor cells inhibited angiogenesis and impaired tumor growth. In orthotopic tumor xenograft studies, EPOR-R129C expression significantly promoted tumor growth associated with increased expression of Ki67 proliferation antigen, enhanced microvessel density, decreased tumor hypoxia, and increased phosphorylation of extracellular-regulated kinases ERK1/2. R103A-EPO antagonist expression in mammary carcinoma cells was associated with near-complete disruption of primary tumor formation in the mammary fat pad.Conclusions/significanceThese data indicate that erythropoietin is an important angiogenic factor that regulates the induction of tumor cell-induced neovascularization and growth during the initial stages of tumorigenesis. The suppression of tumor angiogenesis and progression by erythropoietin blockade suggests that erythropoietin may constitute a potential target for the therapeutic modulation of angiogenesis in cancer.

Project description:Neuroblastoma (NB) is a typical childhood and heterogeneous neoplasm for which efficient targeted therapies for high-risk tumors are not yet identified. The chemokine CXCL12, and its receptors CXCR4 and CXCR7 have been involved in tumor progression and dissemination. While CXCR4 expression is associated to undifferentiated tumors and poor prognosis, the role of CXCR7, the recently identified second CXCL12 receptor, has not yet been elucidated in NB. In this report, CXCR7 and CXCL12 expressions were evaluated using a tissue micro-array including 156 primary and 56 metastatic NB tissues. CXCL12 was found to be highly associated to NB vascular and stromal structures. In contrast to CXCR4, CXCR7 expression was low in undifferentiated tumors, while its expression was stronger in matured tissues and specifically associated to differentiated neural tumor cells. As determined by RT-PCR, CXCR7 expression was mainly detected in N-and S-type NB cell lines, and was slightly induced upon NB cell differentiation in vitro. The relative roles of the two CXCL12 receptors were further assessed by overexpressing CXCR7 or CXCR4 receptor alone, or in combination, in the IGR-NB8 and the SH-SY5Y NB cell lines. In vitro functional analyses indicated that, in response to their common ligand, both receptors induced activation of ERK1/2 cascade, but not Akt pathway. CXCR7 strongly reduced in vitro growth, in contrast to CXCR4, and impaired CXCR4/CXCL12-mediated chemotaxis. Subcutaneous implantation of CXCR7-expressing NB cells showed that CXCR7 also significantly reduced in vivo growth. Moreover, CXCR7 affected CXCR4-mediated orthotopic growth in a CXCL12-producing environment. In such model, CXCR7, in association with CXCR4, did not induce NB cell metastatic dissemination. In conclusion, the CXCR7 and CXCR4 receptors revealed specific expression patterns and distinct functional roles in NB. Our data suggest that CXCR7 elicits anti-tumorigenic functions, and may act as a regulator of CXCR4/CXCL12-mediated signaling in NB.

Dataset Information

Malignant progression and blockade of angiogenesis in a murine transgenic model of neuroblastoma.

Publications

Malignant progression and blockade of angiogenesis in a murine transgenic model of neuroblastoma.

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