Regulation of tumor angiogenesis by Id+ marrow precursor

描述(申请人提供)：这项建议的目的是研究骨髓来源的循环内皮前体细胞(CEP)和造血细胞(HCS)在出生后调节血管生成中的作用。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。我们拟明确ID基因介导和血管内皮生长因子受体VEGFR1(Flt-L)和VEGFR2(FIK-1，KDR)上调调控CEP和HC存活、增殖、动员和募集的机制。我们已经鉴定出循环中的CEPs，AC133(+)VEGFR2(+)，能够从骨髓募集到肿瘤血管床，促进血管生成。我们发现，通过VEGFR2的信号对于CEP的增殖是必不可少的，并且VEGF诱导VEGFR1(+)HC的一个子集的动员，从而影响肿瘤血管网络的启动。此外，VEGF还诱导BM来源的CEPs和HCS表达Id1和Id3。通过骨髓移植，Id1和Id3基因敲除(Id1+/-Id3-/-)小鼠的进一步血管生成缺陷(肿瘤生长、Matrigel血管形成)是可逆的。因此，(Id1+/-Id3-/-)小鼠的原发血管生成缺陷可能是由于血管内皮生长因子/血管内皮生长因子受体2和血管内皮生长因子受体1信号的失调，导致动员失败。我们推测，血管内皮生长因子介导的Id1和/或Id3的上调对于动员VEGFR1(+)Hcs和VEGFR2(+)CEPs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、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CEPs和HCS动员过程中对ID基因和VEGF受体表达的调节作用；3)评估BM来源的CEPs和/或HCS在体内肿瘤血管生成中的生理意义和贡献。这些实验将有助于理解在肿瘤血管床上募集具有血管内皮生长因子反应性ID活性的骨髓前体细胞的机制，并提出阻止肿瘤生长的新的临床策略。

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.