Understanding Mechanisms of Resistance to Anti-angiogenic Treatments

了解抗血管生成治疗的耐药机制

• 批准号: 8616733
• 负责人: ALI SYED ARBAB
• 金额: $ 35.21万
• 依托单位: AUGUSTA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-03-19 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8616733
• 关键词: Address; Adjuvant Therapy; Alkane 1-monooxygenase; Angiogenesis Inhibitors; Angiogenesis Promoter; Angiogenic Factor; Animals; Antibodies; Apoptosis; Arachidonic Acids; Blood Vessels; Blood Volume; Bone Marrow; Bone Marrow Cells; Brain Neoplasms; CXCR4 gene; Cell Survival; Cells; Clinical; Clinical Trials; Data; Diffusion; Diffusion weighted imaging; EGF gene; Endothelial Cells; Failure; Fibroblast Growth Factor 2; Future; Glioblastoma; Glioma; Growth; Growth Factor; Home environment; Homing; Human; Hydroxyeicosatetraenoic Acids; Hypervascular; Hypoxia; Image; Imaging Techniques; Immigration; Immunohistochemistry; In Vitro; Indium-111; Label; Magnetic Resonance Imaging; Malignant - descriptor; Mediating; Modeling; Monitor; Morphology; New Agents; Nude Rats; PTK787; Pattern; Permeability; Phenotype; Platelet-Derived Growth Factor; Play; Process; Rattus; Refractory; Regulation; Reporting; Resistance; Resistance development; Reverse Transcriptase Polymerase Chain Reaction; Role; Signal Transduction; Site; Solid Neoplasm; Stem cells; Stromal Cell-Derived Factor 1; Techniques; Transplantation; Tumor Angiogenesis; Tumor Volume; U251; Vascular Endothelial Growth Factor Receptor; Vascular Endothelial Growth Factors; Vascular Permeabilities; Weight; Western Blotting; angiogenesis; antitumor drug; bevacizumab; cell growth; cellular imaging; chemokine; density; formamidine; gliosarcoma; in vivo; in vivo imaging; inhibitor/antagonist; innovation; irradiation; migration; neoplastic cell; novel; precursor cell; promoter; receptor; research study; resistance mechanism; response; single photon emission computed tomography; time use; tool; tumor; tumor growth; vasculogenesis

DESCRIPTION (provided by applicant): At present survival from malignant glioblastoma (GBM, brain tumor) is usually less than a year. GBM are characterized by release of vascular endothelial growth factor (VEGF), an important regulator and promoter of new vessel formation (angiogenesis) and vascular permeability. Because of initial positive responses noted in clinical trials, it was thought that anti-angiogenic therapy targeting VEGF or VEGF receptors (VEGFRs) would become an effective tool for controlling GBM. However, it is now well recognized that the positive responses are temporary and that the tumors develop resistance and eventually progress, and in some cases with a more aggressive and invasive phenotype. To overcome the failure, it is essential to understand the basic mechanism of resistance to anti-angiogenic therapy. We hypothesize that anti-angiogenic treatment using VEGFR inhibitors (such as vetanalib) will cause hypoxia due to vascular loss and decreased endothelial cell (EC) survival, which will enhance compensatory increases in other pro-angiogenic factors such as stromal-cell derived factor 1 (SDF-1). SDF-1 in turn will induce the mobilization, migration and accumulation of endothelial progenitor cells (EPCs) around or into the tumor. Bone marrow (BM) derived precursor cells are known to promote angiogenesis and pro-growth responses and may be a mechanism for resistance. However it is not known whether EPCs accumulate in the tumor during anti VEGF therapy, or whether decreasing BM cells or neutralizing SDF-1 helps overcome resistance to anti- angiogenic therapy. It would be advantageous to use novel compounds that target multiple sites of angiogenesis to overcome anti-angiogenic resistance. HET0016 is one of the compounds that target multiple sites of angiogenesis. In this proposal we'll make orthotopic human glioma tumor model in nude rat. Tumor bearing animals will be treated either with vetanalib, or HET0016 alone or in combination. Dynamic contrast enhanced MRI (DCE-MRI) will be performed to determine permeability transfer constant (Ktrans), distribution (tumor blood) volume, tumor volume, enhancement pattern, and diffusion parameters in the tumors under basal and treated conditions. Western blot and RT-PCR analysis will determine the expression level of different angiogenic factors/receptors while immunohistochemistry will assess the vascular density and morphology. We expect that treatment resistance tumor will show changes in size, permeability, tumor blood volume, and other MRI parameters. The data may give direct evidence of compensatory/refractory angiogenesis, explain why certain tumors become refractory to anti VEGFR therapy and identify HET0016 as a possible adjuvant therapy in surmounting the tumor resistance to anti-angiogenic therapy. Previous studies by our group showed that transplanted EPCs migrated and incorporated in the tumor angiogenesis due to chemotactic cytokines released from the tumors (such as HIF-1 mediated SDF-1 release). To determine whether decreasing available BM cells or blocking accessible SDF-1, will diminish or even overcome resistance to anti VEGFR or HET0016 therapy. We will use sub lethal irradiation to lower the ability of the BM to release pro-angiogenic cells. In a set of experiments we will also block SDF-1 using specific antibodies or CXCR4 antagonists and thus reduce the ability of EPCs to migrate to the tumor. The initial migration and incorporation of intravenously administered EPCs will be detected by SPECT using In-111 labeled cells and the long term incorporation of the administered cells will be detected by cellular MRI using magnetically labeled cells. These data will be validated by immunohistochemistry. We expect the results of this experimental proposal will shade lights on the mechanisms of resistance to anti- angiogenic treatments and allow clinician to change the strategy of future treatment for GBM or other solid tumors.

描述（由申请人提供）：目前来自恶性胶质母细胞瘤（GBM，脑肿瘤）的存活通常不到一年。 GBM的特征是释放血管内皮生长因子（VEGF），这是新血管形成（血管生成）和血管渗透性的重要调节剂和启动子。由于临床试验中指出的最初阳性反应，因此人们认为针对VEGF或VEGF受体（VEGFR）的抗血管生成疗法将成为控制GBM的有效工具。但是，现在已经有充分认识的是，阳性反应是暂时的，并且肿瘤会产生抵抗力并最终发展，在某些情况下，具有更具侵略性和侵入性的表型。为了克服失败，必须了解抗血管生成治疗的基本机制。我们假设使用VEGFR抑制剂（例如vetanalib）抗血管生成治疗将由于血管丧失和降低内皮细胞（EC）存活而导致缺氧，这将增强其他促血管生成因子的补偿性增加，例如Stromal-Cell衍生因子1（SDF-1）。 SDF-1反过来会诱导内皮祖细胞（EPC）周围或进入肿瘤的动员，迁移和积累。已知骨髓（BM）衍生的前体细胞可促进血管生成和促增长反应，并且可能是抗性的机制。但是，尚不清楚EPC在抗VEGF治疗期间是否积累在肿瘤中，或者降低BM细胞或中和SDF-1是否有助于克服对抗血管生成治疗的抗药性。使用靶向多个血管生成部位的新型化合物来克服抗血管生成抗性，这将是有利的。 HET0016是针对多个血管生成位点的化合物之一。在此提案中，我们将在裸鼠中制作原位的人神经瘤肿瘤模型。肿瘤轴承动物将用vetanalib或单独或组合治疗HET0016。将执行动态对比度增强的MRI（DCE-MRI），以确定在基础和治疗条件下肿瘤中肿瘤中肿瘤中的渗透率转移常数（KTRAN），分布（肿瘤血）体积，肿瘤体积，增强模式和扩散参数。蛋白质印迹和RT-PCR分析将确定不同血管生成因子/受体的表达水平，而免疫组织化学将评估血管密度和形态。我们预计耐药性肿瘤将显示出大小，渗透率，肿瘤血容量和其他MRI参数的变化。数据可能给出了补偿性/难治性血管生成的直接证据，解释了为什么某些肿瘤对抗VEGFR治疗产生难治性，并确定HET0016是可能辅助治疗，以探测抗抗血管生成疗法的肿瘤性。我们组的先前研究表明，由于肿瘤释放的趋化细胞因子（例如HIF-1介导的SDF-1释放），移植的EPC迁移并纳入了肿瘤血管生成中。为了确定减少可用的BM细胞或阻止可访问的SDF-1，是否会降低甚至可以克服对抗VEGFR或HET0016治疗的抵抗力。我们将使用亚致死照射来降低BM释放前血管生成细胞的能力。在一组实验中，我们还将使用特定的抗体或CXCR4拮抗剂阻止SDF-1，从而降低EPC迁移到肿瘤的能力。使用In-1111标记的细胞将检测到静脉内施用的EPC的初始迁移和掺入，并将使用磁性标记的细胞通过细胞MRI检测到施用细胞的长期掺入。这些数据将通过免疫组织化学验证。我们预计该实验建议的结果将使对抗血管生成治疗的耐药机制遮挡，并允许临床医生改变GBM或其他实体瘤的未来治疗策略。