Regulation of tumor angiogenesis by Id+ marrow precursor

描述（由申请人提供）：本提案的目的是研究骨髓（BM）来源的循环内皮前体细胞（cep）和造血细胞（hc）在出生后血管生成调节中的作用。尽管最近发现了调节胚胎发育的血管生成因子，但这些因子和效应细胞在调节肿瘤血管生成中的作用尚不清楚。我们打算确定Id基因介导和血管内皮生长因子受体VEGFR1 （flt -1）和VEGFR2 （FIK-1， KDR）上调调控cep和hc存活、增殖、动员和募集的机制。我们已经确定了循环cep， AC133 (+) VEGFR2(+)，能够从BM募集到肿瘤血管床，加速血管生成。我们发现通过VEGFR2的信号传导对于CEP的增殖至关重要，并且VEGF诱导VEGFR1 (+) hc亚群的动员，从而影响肿瘤血管网络的启动。此外，VEGF在BM源性cep和hc中诱导了Id1和Id3的表达。在Id1和Id3敲除（Id1+/-Id3-/-）小鼠中，进一步的血管生成缺陷（肿瘤生长，基质血管化）通过骨髓移植是可逆的。因此，（Id1+/- id3 -/-）小鼠的原发性血管生成缺陷可能是由于VEGF/VEGFR2和VEGF/VEGFR1信号失调，导致动员失败。我们假设vegf介导的Id1和/或Id3的上调对于VEGFR1(+) hcc和VEGFR2(+) cep的动员是必不可少的。具体目的是：确定肿瘤血管生成过程中Id基因、VEGFR1和VEGFR2在新生血管上的时空表达模式；2)明确趋化因子信号通路在cep和hcc动员过程中对Id基因和VEGF受体表达的调控作用；3)评估脑源性cep和/或hcc在体内模型肿瘤血管生成中的生理意义和贡献。这些实验将有助于了解肿瘤血管床募集vegf反应性和脑基衍生前体的机制，并提出新的临床策略来阻止肿瘤生长。

DESCRIPTION (provided by applicant): The objective of this proposal is to examine the role of bone marrow (BM) - derived circulating endothelial precursor cells (CEPs) and hematopoietic cells (HCs) in the post natal regulation of angiogenesis. Despite recent identification of angiogenic factors regulating embryonic development, the role of such factors and effector cells in modulation of tumor angiogenesis is not clear. We intend to define the mechanisms whereby Id gene mediation along with the upregulation of vascular endothelial growth factor receptors, VEGFR1 (Flt-l) and VEGFR2 (FIK-1, KDR) regulate survival, proliferation, mobilization, and recruitment of CEPs and HCs. We have identified circulating CEPs, AC133 (+) VEGFR2 (+), capable of being recruited from BM to tumor vasculature bed, accelerating angiogenesis. We found that signaling through VEGFR2 is essential for CEP proliferation and that VEGF induces mobilization of a subset of VEGFR1 (+) HCs that affects initiation of the tumor vascular network. Also VEGF induced Id1 and Id3 expression in both BM derived CEPs and HCs. Further angiogenic defects (tumor growth, Matrigel vascularization) in Id1 and Id3 knock out (Id1+/-Id3-/-) mice were reversible by BM transplantation. Thus the primary angiogenic defect in (Id1+/-Id3-/-) mice may be due to dysregulated VEGF/VEGFR2 and perhaps VEGF/VEGFR1 signaling, causing mobilization failure. We hypothesize that VEGF-mediated upregulation of Id1 and/or Id3 is essential for mobilization of VEGFR1(+) HCs and VEGFR2(+) CEPs. Specific aims are: Determine the temporal and spatial expression patterns of Id genes, VEGFR1, and VEGFR2 on neovessels during tumor angiogenesis, 2) Define the role of chemokine signaling pathways for the regulation of Id gene and VEGF receptor expression during the mobilization of CEPs and HCs, 3) Assess the physiological significance and contributions of BM-derived CEPs and/or HCs to tumor angiogenesis in vivo models. These experiments will lead to the understanding of the mechanisms involved in the recruitment of VEGF-responsive Id competent BM-derived precursors to the tumor vasculature bed and suggest new clinical strategies to block tumor growth.