基于VEGFR靶点的小分子肿瘤靶向抑制肽的99Tcm标记及鉴定

目的 探讨基于血管内皮生长因子受体( vascular endothelial growth factor receptor,VEGFR)靶点的小分子肿瘤靶向抑制肽理想的放射性核素99 Tcm标记方法.方法 多肽QKRKRKKSRKKH、RKRKRKKSRYIVLS分别经双功能螯合剂S-acetyl-MAG3、GA(D)GG、HYNIC修饰后进行放射性核素99 Tcm标记,HPLC及纸层析法鉴定其标记率及放化纯度,3 H-TdR参入实验鉴定其抑制细胞增殖的能力,体外受体竞争结合实验鉴定其受体结合活性.结果 以HYNIC为双功能螯合剂,这2条多肽的99 Tcm标记率分别为(94.13±1.77)％、(93.79±3.53)％,明显高于S-acetyl-MAG3、GA(D) GG修饰多肽的标记率.经HYNIC修饰后的多肽对肿瘤细胞A549增殖的抑制率约为(32.86±3.36)％、(61.50±4.50)％,与修饰前无明显变化(P＞0.05)；多肽标记后仍保持了良好的VEGFR结合活性,室温下放置24 h后,放化纯度仍高达90％左右.结论 以HYNIC为双功能螯合剂,以TPPTS为协同配体及还原剂,多肽QKRKRKKSRKKH、RKRKRKKSRYIVLS的99Tcm标记率高,且仍具有良好的抑制肿瘤细胞增殖的能力和VEGFR结合活性.

Radionuclide labeling of small molecular inhibitory peptides targeting VEGF receptor

Objective To investigate radionuclide labeling methods of small molecular inhibitory peptide targeting vascular endothelial growth factor receptor(VEGF receptor) of tumor with 99Tcm.Methods After being modified by S-acetyl-MAG3,GA(D)GG and HYNIC respectively,QKRKRKKSRKKH and RKRKRKKSRYIVLS were labeled with 99Tcm.Labeling efficiency and radiochemical purity was identified by paper chromatography and HPLC.The inhibitory affect of peptide to tumor cell was testified by 3H-TdR incorporation.Receptor competition binding assay was used to testify the affinity of peptide ligand based on A549 cells.Results The labeling efficiency of two peptide modified by three bifunctional chelating agents was about 78%,40% and 94% respectively.The inhibitory efficiency of HYNIC-QKRKRKKSRKKH and HYNIC-RKRKRKK-SRYIVLS to A549 cells was about(32.86±3.36)% and(61.50±4.50)%,and did not have statistically significant difference with QKRKRKKSRKKH and RKRKRKKSRYIVLS.Meanwhile the 99Tcm-HYNIC-QKRKRKKSRKKH and 99Tcm-HYNIC-RKRKRKKSRYIVLS retained a good stability and binding activity of VEGF receptor in A549 cells.Conclusion HYNIC-QKRKRKKSRKKH and HYNIC-RKRKRKKSRYIVLS have a high labeling efficiency with TPPTS as a reducing agent and collaborative ligand,and the labeled agents retain inhibiting activity and binding activity of receptor to A549 cells.