Experimental studies of depreotide labeled with 99Tcm and the affinity with human lung adenocarcinoma cell line A549

Objective To establish a simple and reliable method of making 99Tcm-depreotide by direct labeling. Furthermore, to investigate 99Tcm-depreotide's specific receptor binding properties in vitro with human lung adenocarcinoma cell line A549, and to evaluate the potentiality of 99Tcm-depreotide as a through a direct labeling using SnCl2 as reductant. Compared the labeling efficiency in different pH and temperature, then searched the best labeling method. Assessed the radiochemical purity and stability in uptake kinetics, then stagnation and half time were compared at different temperature and time points, and that 99Tcm-depreotide was incubated with A549 cell the internalization and surface-bound activity were group was higher than that of pH5.0 and pH7.0 groups. At the same pH,the labeling rate of all of the three The uptake rate increased with temperature at the same time point, and the peak time of maximum uptake was 60min at 37 ℃. The cleaning curves were similar at different temperature,and the half cleaning time at 37 ℃ was 48 min. Conclusions When depreotide was labeled with 99Tcm, the temperature could not be too high(＜15 ℃) and the pH would better be less than 6.0. 99Tcm-depreotid was a potential somatostatin receptor imaging agent with its appropriate the peak time of maximum uptake and the half cleaning time at 37 ℃. Key words: Receptors,somatostatin; Isotope labeling; Lung neoplasms; 99Tcm- depreotide