Regulation of tumor angiogenesis by Id+ marrow precursor

描述（由申请人提供）：本提案的目的是检查骨髓（BM）源性循环内皮前体细胞（CEP）和造血细胞（HC）在纳塔尔后血管生成调节中的作用。尽管最近鉴定出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。我们打算定义Id基因介导沿着血管内皮生长因子受体VEGFR 1（Flt-l）和VEGFR 2（FIK-1，KDR）的上调调节CEP和HC的存活、增殖、动员和募集的机制。我们已经鉴定了循环CEP，AC 133（+）VEGFR 2（+），能够从BM募集到肿瘤血管床，加速血管生成。我们发现，通过VEGFR 2的信号传导对于CEP增殖是必不可少的，并且VEGF诱导VEGFR 1（+）HC亚群的动员，其影响肿瘤血管网络的启动。VEGF还诱导Id 1和Id 3在BM来源的CEP和HC中的表达。通过BM移植，Id 1和Id 3敲除（Id 1 +/-Id 3-/-）小鼠中的进一步血管生成缺陷（肿瘤生长、基质胶血管化）是可逆的。因此，（Id 1 +/-Id 3-/-）小鼠中的原发性血管生成缺陷可能是由于VEGF/VEGFR 2和可能的VEGF/VEGFR 1信号转导失调，导致动员失败。我们假设VEGF介导的Id 1和/或Id 3的上调对于VEGFR 1（+）HC和VEGFR 2（+）CEP的动员是必不可少的。具体目标是：确定肿瘤血管生成过程中Id基因、VEGFR 1和VEGFR 2在新血管上的时空表达模式，2）确定趋化因子信号传导途径在CEP和HC动员过程中调节Id基因和VEGF受体表达的作用，3）评估BM衍生的CEP和/或HC对体内模型肿瘤血管生成的生理意义和贡献。这些实验将导致了解参与招募VEGF响应性Id主管BM衍生的前体到肿瘤血管床的机制，并提出新的临床策略来阻断肿瘤生长。

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.