Hu Jia, Qin Guangming, Zhang Yongxue, An Rui, Lan Xiaoli
Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
J Huazhong Univ Sci Technolog Med Sci. 2007 Aug;27(4):471-4. doi: 10.1007/s11596-007-0432-3.
The validity of (99m)Tc-YIGSR, a novel receptor radio-tracer, in imaging the Ehrlich ascites tumor was evaluated. YIGSR, a pentapeptide of laminin, was labeled with (99m)Tc by using a bifunctional chelator S-Acetly-NH(3)-MAG(3). The MIBI was labeled with (99m)Tc by following the kit instruction. The mice of tumor group were intravenously injected 1-2 mCi of (99m)Tc-YIGSR or (99m)Tc-MIBI via caudal vein, immobilized and imaged under a Gamma camera. The same procedure was performed in mice of blockade group, in which the unlabeled YIGSR was previously injected to block the receptor-recognition sites, and inflammation group serving as control. The reverse-phase Sep-Pak C(18) chromatogram was found to have an essentially complete conjugation between YIGSR and S-Acetly-NH(3)-MAG(3). The conjugated YIGSR could be radio-labeled successfully with (99m)Tc at room temperature and neutral pH, with a radio-labeling yield of 62%. Without the chelator S-Acetly-NH(3)-MAG(3), the YIGSR was labeled with (99m)Tc at an efficiency of 4%. The imagological study revealed obvious tumor accumulation of (99m)Tc-YIGSR 15 min after the injection, and the uptake peaked after 3 h with a tumor-to-muscle ratio (T/M) of 11.36. The radio-tracer was slowly cleared up and resulted in a T/M of 3.01 at the 8th h after the injection. As for blocked group, the tumor uptake of radiotracer was significantly lower, with the highest T/M being 4.61 after 3 h and 0.89 after 8 h. The T/M was 3.72 at the 3rd h and 1.29 at the 8th h after the (99m)Tc-YIGSR injection in the inflammatory group. The T/M was significantly higher in tumor group than in inflammatory group or control group (P<0.001). In the 99mTc-MIBI group, the T/M was 1.40 at the 3rd h and 0.55 at the 8th h after the injection, which showed a significant difference as compared with (99m)Tc-YIGSR (P<0.001). It is concluded that YIGSR can be successfully radiolabelled by using S-Acetly-NH(3)-MAG(3). (99m)Tc-YIGSR has many advantages in tumor imaging, such as quick and clear visualization, high sensitivity and specificity, and satisfactory target/non-target ratio (N/NT). It promises to be tumor radio-tracer.
评估了新型受体放射性示踪剂（99m）Tc - YIGSR对艾氏腹水瘤成像的有效性。层粘连蛋白的五肽YIGSR通过双功能螯合剂S - 乙酰 - NH(3)-MAG(3)用（99m）Tc进行标记。按照试剂盒说明书用（99m）Tc标记甲氧基异丁基异腈（MIBI）。肿瘤组小鼠经尾静脉注射1 - 2毫居里的（99m）Tc - YIGSR或（99m）Tc - MIBI，固定后在γ相机下成像。在阻断组小鼠中进行相同操作，该组预先注射未标记的YIGSR以阻断受体识别位点，炎症组作为对照。发现反相Sep - Pak C(18)色谱图显示YIGSR与S - 乙酰 - NH(3)-MAG(3)之间基本完全共轭。共轭的YIGSR在室温及中性pH条件下能够成功地用（99m）Tc进行放射性标记，放射性标记产率为62%。在没有螯合剂S - 乙酰 - NH(3)-MAG(3)的情况下，YIGSR用（99m）Tc标记的效率为4%。影像学研究显示，注射后15分钟（99m）Tc - YIGSR在肿瘤中有明显聚集，3小时后摄取达到峰值，肿瘤与肌肉比值（T/M）为11.36。该放射性示踪剂清除缓慢，注射后8小时T/M为3.01。对于阻断组，放射性示踪剂在肿瘤中的摄取显著降低，3小时后最高T/M为4.61，8小时后为0.89。炎症组在注射（99m）Tc - YIGSR后3小时T/M为3.72，8小时后为1.29。肿瘤组的T/M显著高于炎症组或对照组（P<0.001）。在（99m）Tc - MIBI组中，注射后3小时T/M为1.40，8小时后为0.55，与（99m）Tc - YIGSR相比有显著差异（P<0.001）。结论是YIGSR可以通过使用S - 乙酰 - NH(3)-MAG(3)成功地进行放射性标记。（99m）Tc - YIGSR在肿瘤成像方面有许多优点，如快速清晰的可视化、高灵敏度和特异性以及令人满意的靶/非靶比值（N/NT）。它有望成为肿瘤放射性示踪剂。
