Nitric Oxide in Tumor Angiogenesis, Microcirculation and Radiation Therapy

描述（由申请人提供）：肿瘤血流的可再现控制，这是向实体瘤最佳输送药物和氧气所需的，仍然是一个难以实现的目标。一氧化氮（NO）是一系列生理和病理过程的多功能介质。研究表明，来源于血管内皮NO合酶的NO诱导血管生成并维持肿瘤血流。最近的研究结果表明，血管NO介导的招聘血管周围细胞的血管生成的血管，以及分支，纵向延伸和随后的稳定的血管。然而，初步的研究表明，NO产生的肿瘤和基质细胞以外的血管区可能与血管成熟的过程中竞争。该项目的中心假设是，选择性定位血管周围的NO改善肿瘤血管形态和功能，药物和氧气的输送，从而提高伴随的细胞毒性治疗的疗效。 将研究在小鼠透明窗模型中生长的原位神经胶质瘤和乳腺肿瘤。在目标1中，通过遗传和药理学修饰将阻断NO产生的非血管来源，并增加血管NO。这些修饰对肿瘤血管功能和组织氧合的影响将通过高分辨率活体显微镜技术和免疫组织化学来确定。将使用荧光报告基因转基因小鼠在体内监测血管周围细胞。最后，将确定NO修饰期间肿瘤对分次辐射的反应。 血管生成素（Ang）-Tie 2途径已显示通过血管周围细胞募集介导血管成熟。在目标2中，将使用最近建立的体外迁移测定和组织工程血管模型以及肿瘤模型来确定血管NO参与Ang-Tie 2诱导的血管周细胞募集以及NO依赖性血管周细胞募集的下游信号传导。 最近的结果表明，阻断血管内皮生长因子受体2（VEGFR 2）通过Tie 2受体信号传导瞬时改善血管周围细胞覆盖，组织氧合和对肿瘤放射治疗的反应。在目标3中，将使用目标1的模型和方法确定血管NO在抗VEGFR 2治疗诱导的血管效应中的作用以及NO的血管选择性定位对组合抗VEGFR 2和放射治疗的功效的影响。 为了支持中心假设，初步研究表明，消除非血管来源的NO改善了肿瘤血管的结构和功能，并增强了肿瘤对分次放疗的反应。该项目将推进对NO介导的血管成熟的基本理解，并帮助开发新的策略来改善药物和氧气向肿瘤的输送。

DESCRIPTION (provided by applicant): The reproducible control of tumor blood flow, which is required for the optimal delivery of drugs and oxygen to solid tumors, remains an elusive goal. Nitric oxide (NO) is a multifunctional mediator of an array of physiological and pathological processes. It has been shown that NO derived from vascular endothelial NO synthase induces angiogenesis and maintains tumor blood flow. Recent results show that vascular NO mediates the recruitment of perivascular cells to angiogenic vessels, as well as the branching, longitudinal extension and subsequent stabilization of the vessels. However, preliminary studies suggest that NO produced by tumor and stromal cells outside the vascular area may compete with the process of vessel maturation. The central hypothesis of this project is that selective localization of NO around blood vessels improves tumor vascular morphology and function, the delivery of drugs and oxygen, and thus the efficacy of concomitant cytotoxic therapy. Orthotopic glioma and breast tumors grown in transparent window models in mice will be studied. In Aim 1, non-vascular sources of NO production will be blocked and vascular NO will be increased by means of genetic and pharmacological modifications. The effect of these modifications on tumor vascular function and tissue oxygenation will be determined by high-resolution intravital microscopy techniques and immunohistochemistry. Perivascular cells will be monitored in vivo using fluorescence-reporter transgenic mice. Finally, the tumor response to fractionated radiation during NO modifications will be determined. The angiopoietin (Ang)-Tie2 pathway has been shown to mediate vessel maturation via perivascular cell recruitment. In Aim 2, involvement of vascular NO in Ang-Tie2-induced perivascular cell recruitment as well as in downstream signaling of NO-dependent perivascular cell recruitment will be determined using recently established in vitro migration assays and a tissue-engineered blood vessel model as well as tumor models. Recent results show that blockade of vascular endothelial growth factor receptor 2 (VEGFR2) transiently improves perivascular cell coverage, tissue oxygenation and response to radiation therapy in tumors via Tie2 receptor signaling. In Aim 3, the role of vascular NO in anti-VEGFR2 treatment-induced vascular effects and the impact of vessel-selective localization of NO on the efficacy of combined anti-VEGFR2 and radiation treatments will be determined using the models and methods of Aim 1. In support of the central hypothesis, preliminary studies show that elimination of non-vascular sources of NO improves the structure and function of tumor vessels and enhances tumor response to fractionated radiation therapy. This project will advance the basic understanding of NO-mediated vessel maturation and help develop novel strategies to improve the delivery of drugs and oxygen to tumors.