VEGFR2靶向胶质瘤探针在判定脑部胶质瘤边界及侵袭性中的价值研究

Glioma is one of the most malignant and invasive brain tumor.Routine examination approaches were either unable to detect the infiltrative tummor cells around solid tumor or determining actual tumor boundary. It is critical to establish a new imaging approach to determine actual glioma boundary for more effetive treatment stategies of brain glioma.Based on our prebious study, we have found VEGF could significantly increase the Blood-brain barrier permeability,VEGF/VEGFR2expression was obviously higher in peri-tumor area of glioma, which suggest VEGFR2 could be a specific maker for detecting glioma boundary and tumor cll around infiltration. We planned to establish a new VEGFR2-based effectice, high specific glioma targeting MRI probe, composed of other three BSA which conjugating other three components biotin, VEGFR2-Ab and Gd-DTPA.Hopefully,this study will apply this gioma specfic probe to detect actual tumor boundary, identify tumor invasion ablity and evaluate anti-angiogenesis therapy effect. It could also provide an alternative non invasive approch for glioma early diagnosis,tumor angiogenesis observation,tumor biological behavior study and anti-angiogenesis therapy evaluation.

脑胶质瘤是恶性程度极高，侵袭性极强的脑部肿瘤。常规检查手段往往只能检出实体瘤，未成瘤体的肿瘤周围浸润细胞难以有效检测。因此，明确肿瘤真实边界是提高胶质瘤有效治疗的关键。本研究在前期研究中发现VEGF能显著提高血脑屏障通透性，胶质瘤肿瘤周围明显增高的VEGF/VEGFR2可以成为探测肿瘤边界及浸润范围的靶向分子。因此，本研究拟研制基于VEGFR2的胶质瘤靶向造影剂BSA-Biotin-anti VEGFR2-Gd-DTPA。通过体外BSA与生物素，VEGFR2单克隆抗体及Gd-DTPA高效连接，构建稳定、高效、高度特异性地靶向胶质瘤探针。本研究将应用该靶向探针检测肿瘤真实边界、评价肿瘤侵袭度及抗血管生成治疗后疗效，有望为活体客观评价胶质瘤血管生成提供新的可靠方法，还可为胶质瘤早期诊断、生物学行为的研究、靶向抗血管生存治疗及疗效评价提供新的无创性方法。

c-Met是参与肿瘤细胞生长、侵袭、转移和血管生成的受体酪氨酸激酶。c-Met的过度表达是经常出现在恶性。在这方面，我们评估c-Met分子探针在体外和体内对于脑胶质瘤的治疗作用。本实验主要采用了人胶质瘤细胞系U87和大鼠星形胶质细胞系。利用针对c-Met受体短肽cMBP2肽合成了靶向分子探针Den-cMBP2。通过生长抑制实验，划痕实验、细胞凋亡检测和免疫印迹观察cMET对U87细胞的抑制作用。此外，原位胶质瘤裸鼠模型被用来在探针的体内疗效。免疫组织化学分析表明，cMet在GBM小鼠原位模型中高表达，特别是在肿瘤的边缘表达更强。Den-cMBP降低癌细胞的繁殖能力和迁移能力，并促进细胞凋亡，但是对大鼠星形胶质细胞只有轻微的影响。Den-cMBP治疗抑制的GBM肿瘤细胞信号分子的活化。有趣的是，Den-CMBP对cMet表达几乎没有影响，而主要抑制cMet及其下游蛋白的磷酸化。在体内，Den-cMBP抑制裸鼠上胶质瘤的生长，并延长生存期。与体外实验结果类似的是，Den-cMBP对cMet表达几乎没有增加，cMet及其下游蛋白的磷酸化被抑制了。这个研究证明cMET靶向分子探针对于胶质瘤有治疗作用，可能今后可以在人胶质瘤的治疗上发挥作用