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目的探讨~(18)F标记抗人表皮生长因子受体2(HER2)亲和体探针在HER2过表达胃癌中的示踪作用。方法化学合成制备C末端含半胱氨酸的抗HER2亲和体Z_(HER2):342,通过双功能螯合剂1,4,7-三氮杂环壬烷-1,4,7三乙酸的马来酰亚胺衍生物(NOTA-MAL)与巯基的加成反应合成NOTA-MAL-Cys59-ZHER2:342偶联物(简称偶联物),经~(18)FAl一步法定位标记制得新型HER2靶向分子探针~(18)FAl-NOTA-MAL-Cys59Z_(HER2):342(简称探针),并经高效液相色谱法(HPLC)进行质量控制。构建NOD SCID鼠HER2高表达胃癌NCI N87移植瘤模型。进行体外细胞摄取、阻断、竞争结合实验和模型鼠micro PET显像以评价探针的靶向能力。结果~(18)F标记探针放化纯度>95%。细胞结合实验显示HER2过表达NCI N87细胞对~(18)F标记亲和体的摄取速度快,孵育15 min后接近摄取高峰,约(7.48±0.49)%ID。阻断HER2后,细胞对标记物的摄取水平显著下降,15 min为(0.85±0.09)%ID(P<0.05),说明NCI N87对亲和体的摄取是通过HER2所特异性介导的。细胞竞争结合实验测得IC50为9.4 n M,说明探针与HER2结合亲和力高。NOD SCID鼠micro PET显像肿瘤摄取高,30 min为(7.22±0.24)%ID/g。阻断组micro PET显像肿瘤摄取显著降低,1h为(2.56±0.11)%ID/g(P<0.05)。探针主要经肾脏排泄。结论新型探针标记方便,对HER2过表达胃癌靶向能力强。
Objective To investigate the tracing effect of ~ (18) F-labeled anti-human epidermal growth factor receptor 2 (HER2) probe on HER2-overexpressing gastric cancer. Methods The C-terminal cysteine-containing anti-HER2 antibody Z_ (HER2): 342 was synthesized by chemical synthesis. The bifunctional chelator 1,4,7-triazacyclononane-1,4,7-triacetate NOTA-MAL-Cys59-ZHER2: 342 conjugate was synthesized by the addition reaction of maleimide derivative (NOTA-MAL) and thiol. The new HER2-targeted molecular probe, FAl-NOTA-MAL-Cys59Z_ (HER2): 342 (referred to as probe), was used for quality control by high performance liquid chromatography (HPLC) Construction of NOD SCID murine HER2 overexpressing gastric cancer NCI N87 xenograft model. In vitro cellular uptake, blocking, competition binding experiments and model mouse micro PET imaging were performed to assess the targeting ability of the probe. Results ~ (18) F labeled probe radiochemical purity> 95%. Cell-binding assay showed that the uptake of ~ (18) F-labeled affibodies in HER2-overexpressing NCI N87 cells was rapid and reached a peak of (7.48 ± 0.49)% ID after 15 min of incubation. After blocking HER2, the cellular uptake of the marker decreased markedly (15% vs. (0.85 ± 0.09)% ID) (P <0.05), indicating that the uptake of the affinity complex by NCI N87 was specifically mediated by HER2. IC50 was 9.4 nM in the cell competition binding assay, indicating that the probe has high binding affinity to HER2. NOD SCID mice showed high tumor uptake of micro PET and (7.22 ± 0.24)% ID / g at 30 min. The tumor uptake of micro PET imaging in the blocking group was significantly lower than that of the control group (2.56 ± 0.11)% ID / g at 1 hour (P <0.05). Probes are mainly excreted by the kidneys. Conclusion The new probe is convenient for labeling and targeting HER2 overexpressing gastric cancer.