VEGF受体结合抑制肽的筛选及其特性鉴定

Screening and characterization of inhibiting peptides binding to the tumor vascular growth factor receptor

目的 筛选能抑制VEGF与血管内皮细胞表面受体结合的VEGF模拟短肽 ,探讨小分子短肽作为血管内皮细胞生长抑制剂、肿瘤疫苗的可行性。方法 以抗 VEGF单克隆抗体分别对噬菌体随机 7肽、12肽库进行筛选。通过硝酸纤维膜斑点印迹法进行阳性克隆鉴定。用噬菌体克隆免疫小鼠检验这种短肽可否模拟VEGF的抗原决定簇诱发机体产生能与VEGF结合的抗体 ,研究小鼠抗血清、噬菌体表达的 7肽和 12肽以及人工合成 7肽对人脐静脉血管内皮细胞 (HUVEC)生长的抑制作用。结果 对肽库进行 3轮筛选后 ,噬菌体克隆具有良好的富集效果。硝酸纤维膜斑点印迹法证实阳性率达到 10 0 % ,测序结果显示噬菌体上的短肽有共同序列 :GWYYDAL、VASAVFYSALVE。这两种噬菌体短肽免疫小鼠能激发产生高效价的抗 VEGF抗体。噬菌体表达的 7肽和 12肽对HUVEC的生长有明显的抑制作用。由短肽GWYYDAL阳性克隆免疫的抗血清对VEGF诱导的内皮细胞生长起抑制作用 ,人工合成的 7肽 (GWYYDAL)呈剂量依赖性阻拮VEGF促HUVEC增殖作用。结论 从噬菌体肽库中筛选到的噬菌体短肽GWYYDAL、VASAVFYSALVE模拟了VEGF的抗原表位 ,为研究VEGF受体结合抑制肽和设计肿瘤疫苗奠定了实验基础。

Objective To screen the phage-epitope library to predict the receptor recognition site on VEGF,identify peptide that is able to block the interaction of VEGF-KDR and to find a potent vaccine against tumor angiogenesis through targeting VEGF. Methods Two phage-epitope libraries were screened with two anti-VEGF neutralizing monoclonal antibodies JH121 and VG189. The clones were tested by Dot blot and the positive clones were used to immunize mice. The serum, phage peptides and 7-mer peptide(GWYYDAL) were added to measure their effects on the growth of HUVEC(human umbilical vascular endothelial cell). Results All the selected clones gave strong signal in Dot blot. The 7-mer peptide and 12-mer peptide selected from the peptide library elicited strong anti-VEGF antibody immuno-reaction in mice. The antibody induced by peptide GWYYDAVL abolished VEGF-induced HUVEC growth. Moreover, the peptide GWYYDAL, VASAVFYSALVE displaying on phage and the synthetic peptide, also inhibited the growth of HUVEC. Conclusion Our results suggested that the two peptides GWYYDAL and VASAVFYSALVE were both effective mimickers of VEGF and might function as potent inhibitors of KDR.