^(125)I-NT类似物与人结肠癌细胞HT29体外结合特性研究

In vitro binding characteristics of ^(124)I labeled neurotensin analogue NT_2 to human colonic adenocarcinoma cell line HT29

目的设计神经紧张肽(NT)C 端六肽 NT(8-13)类似物 NT_2:Lys-Arg-Pro-Tyr-Tle-Leu,并研究高比活度(125)~I-NT_2与人结肠癌细胞 HT29 体外结合特性。方法采用氯胺 T 法对 NT_2进行(125)I 标记,用 Sep-Pak 柱纯化,以高效液相色谱法(HPLC)检测标记产物,通过(125)~I-NT_2与 HT29细胞体外结合实验条件的选择,确定细胞量、保温温度和时间,并在选定条件下进行体外受体饱和实验,研究其亲和特性。结果①(125)~I-NT_2标记率为76%,放化纯>98%,比活度为9.71×10^(12)Bq/mmol。②(125)~I-NT_2与 HT29细胞结合具有饱和性,在细胞量、保温温度和时间分别为10~6个、25℃和1 h 条件下,平衡解离常数(K_d)为(0.745±0.418)nmol/L,最大结合容量(B_(max))为(0.103±0.060)pmol/10~6 cell。结论NT_2与 HT29细胞具有较高的亲和力,在人结肠癌显像中具有潜在的应用前景。

Objective To study the binding properties of radioiodinated peptide neurotensin analog ^125I-NT2 through its binding with HT29 cells in vitro. Methods NT2（Lys-Arg-Pro-Tyr-Tle-Leu） was labeled with NaOmi by Ch-T, purified by Sep-Pak column and assessed by high performance liquid chromatography （HPLC）. The incubation time, cell concentration and temperature for ^125I-NT2 binding to HT29 cells were carried out in order to obtain optimal labeling condition. Saturable binding between ^125I-NT2 and HT29 cells was also performed in order to investigate the binding affinity. Results ①The labeling rate of ^125I- NT2 was 76%. The radiochemical purity was 〉98%. The specific activity was 9.71 × 10^12 Bq/mmol. ②The optimal condition of binding： cell number, temperature and time of incubation were 106, 25℃ and 1 h respectively. The Kd and Bmax were （0.745 ±0.418） nmol/L and （0. 103 ±0.060） pmol/10^6 cell. Conclusion ^125I-NT2 has high affinity of binding to HT29 ceils and it may be a promising targeting agent for the imaging of colon adenocarcinoma.