Marenco Manuela, Lodola Lorenzo, Persico Marco G, Frangipane Vanessa, Facoetti Angelica, Aprile Carlo, Hodolič Marina
Nuclear Medicine Unit, IRCCS Policlinico San Matteo Foundation, Pavia, Italy.
University School for Advanced Studies IUSS, Pavia, Italy.
Curr Pharm Biotechnol. 2018;19(9):754-759. doi: 10.2174/1389201019666180829152314.
Neurotensin receptors are overexpressed in several cancer types including pancreatic ductal adenocarcinoma. Three NTR subtypes have been cloned: NTR-1, NTR-2 and NTR-3. The most expressed NTR-1 is not present in normal pancreatic tissue and has a low expression in chronic pancreatitis.
Objective of this study was to test in vitro affinity of the new 68Ga labelled neurotensin analogue DOTA-NT-20.3 (fragment 6-13, Ac-Lys(DOTA)-Pro-Arg(N-CH3)-Arg-Pro-Tyr-Tle-Leu) on the human pancreatic ductal adenocarcinoma cell line AsPC-1.
For the preparation of 68Ga-DOTA-NT-20.3, 68GaCl3 solution (eluted from 68Ge/68Ga generator) and 50 μg of precursor (Iason, Graz, Austria) water dissolved were used in an automatic synthesis module. The labeled compound was added to cell culture flask and incubated at 37°C. At various time points after tracer addition up to 80min, cells were recovered, rinsed and counted for radioactivity. Results were expressed as percent binding normalized to 200000 cells and affinity parameters were calculated.
Labeling yield was ≥98 %. The molar ratio between labelled and total peptide was about 1/400. AsPC-1 cell line showed rapid uptake of the tracer including surface and internalized binding, tending to a plateau phase 80 min after tracer addition (11%/200.000 cells). The Kd (7.335 pmol) and Bmax (90.52 kBq) value indicated high tracer affinity for AsPC-1cell line especially if compared with the literature data regarding other malignancies (e.g. colonic cancer cell line). Binding sites were 1.09x106 sites per cell.
New tracer 68Ga-DOTA-NT-20.3 can be a suitable candidate for the clinical use in patients with pancreatic ductal adenocarcinoma.
神经降压素受体在包括胰腺导管腺癌在内的多种癌症类型中过表达。已克隆出三种神经降压素受体亚型：NTR-1、NTR-2和NTR-3。表达最多的NTR-1在正常胰腺组织中不存在，在慢性胰腺炎中表达较低。
本研究的目的是在体外测试新型68Ga标记的神经降压素类似物DOTA-NT-20.3（片段6-13，Ac-Lys(DOTA)-Pro-Arg(N-CH3)-Arg-Pro-Tyr-Tle-Leu）对人胰腺导管腺癌细胞系AsPC-1的亲和力。
为制备68Ga-DOTA-NT-20.3，在自动合成模块中使用68GaCl3溶液（从68Ge/68Ga发生器洗脱）和50μg溶解于水的前体（Iason，格拉茨，奥地利）。将标记化合物加入细胞培养瓶中，在37°C下孵育。在加入示踪剂后长达80分钟的不同时间点，回收细胞，冲洗并计数放射性。结果以相对于200000个细胞的结合百分比表示，并计算亲和力参数。
标记产率≥98%。标记肽与总肽的摩尔比约为1/400。AsPC-1细胞系显示出对示踪剂的快速摄取，包括表面结合和内化结合，在加入示踪剂80分钟后趋于平稳期（11%/200000个细胞）。Kd（7.335皮摩尔）和Bmax（90.52千贝克勒尔）值表明示踪剂对AsPC-1细胞系具有高亲和力，特别是与关于其他恶性肿瘤（如结肠癌细胞系）的文献数据相比。每个细胞的结合位点为1.09×106个位点。
新型示踪剂68Ga-DOTA-NT-20.3可能是胰腺导管腺癌患者临床应用的合适候选者。
