荷瘤裸鼠放射自显影受体辨别的实验研究(英文)

Receptor discrimination with autoradiography in tumor-bearing nude mice

背景应用放射性核素标记小分子肽类配体进行肿瘤受体显像,针对肿瘤组织所表达的高密度αvβ3受体,发展放射性标记的含RGD序列的高选择性αvβ3受体拮抗剂,是目前肿瘤受体显像研究的热点。目的以实验动物为基础,探讨放射性核素标记小分子环形多肽RGD-4CY实现肿瘤αvβ3受体显像的可行性。设计完全随机的实验对照。地点和对象实验在解放军第三军医大学西南医院核医学中心完成研究对象为25只正常小鼠和15只荷人QBC939胆管癌裸鼠,由解放军第三军医大学实验动物中心提供,4～6周龄,体质量15～20g。干预采用Iodogen法标记、SEP-PAKC18柱分离纯化制备125I-RGD-4CY。取25只正常小鼠与15只荷人QBC939胆管癌裸鼠,经尾静脉注射125I-RGD-4CY0.1mL(370kBq),分别于注射后10,30,60,120和240min各取5只与3只处死,测定体内放射性的生物分布。取3只荷瘤裸鼠各注射0.1mL(3.7MBq)125I-RGD-4CY,1h后处死并行全身放射自显影。主要观察指标125I-RGD-4CY的放射化学纯度;125I-RGD-4CY的体内分布及动力学特点,肿瘤(T)与非肿瘤组织(NT)放射性比值;自显影图像中瘤体及正常组织的放射性分布。结果125I-RGD-4CY的放射化学纯度为99%。正常小鼠血液放射性清除和肝脏放射性下降迅速,肠道无明显增加,主要通过肾脏排泄。

BACKGROUND:Tumor receptor scintigraphy by using small molecule peptide labeled with radionucide is nowadays one of the foremost border research domain in molecular nuclear medicine. To aim directly at the high density of alpha(v)beta(3)receptor expressing in tumor tissues, it is the research hotspot of tumor receptor imaging at present to develop high selectivity αvβ3 receptor antagonist containing RGD motif labeled with radionucide.OBJECTIVE:To investigate the possibility of RGD 4CY labeled with radionuclide to perform tumor αvβ3 receptor scintigraphy according to the basis of experimental animal.DESIGN:A completely randomized controlled trial.SETTING and PARTICIPANTS:The experiment was completed in Nuclear Medicine Center, Southwest Hospital,Third Military Medical University of Chinese PLA.Twenty five healthy mice and fifteen QBC939(human cholangiocarcinoma)with a mass of(15-20)g and aged 4-6 weeks were provided by the center of Third Military Medical University of Chinese PLA. INTERVENTION: RGD 4CY was labeled with 125I by using routine Iogogen method, subsequently separated by SEP PAK C18 column.The biodistribution of 125I RGD 4CY was studied separately in 25 normal mice and 15 nude mice bearing human QBC939 cholangiocarcinoma after venous injection of 125I RGD 4CY 0.1 mL(370 kBq) at 10,30,60,120 and 240 minutes,and the autoradiography was performed in 3 tumor bearing nude mice after venous injection of vein at 1 hour.MAIN OUTCOME MEASURES:The radiochemical purity of 125I RGD 4Cy;the biodistribution and kinetic characteristics of 125I RGD 4CY;the radioactivity ratio of tumor tissues(T)and no tumor tissues(NT) and the radioactivity distribution of tumor and normal tissues on the autoradiography images of tumor bearing nude mice were mesured.RESULTS:The radiochemical purity of 125I RGD 4CY was 99%. Biodistribution showed that the radioactive descent was rapid in blood and liver; The radioactivity was mainly eliminated through kidneys; The amount of radioactivity was only 32%and 44%respectively in lungs and muscles of the liver at 120 minutes(t values were 3.33 and 3.64,P< 0.05).The tumor radioactivity was higher than that of lungs, muscles and intestines at all phases in tumor bearing nude mice(t values were 3.18-13.24,P< 0.05), and the T/NT radioactive ratio was 26.0,26.0 and 8.7 respectively at 240 minutes. Autoradiography displayed that the radioactive image was the highest in tumor region and there was only a small quantity radioactive distribution in lungs, muscles, neck and other soft tissues. CONCLUSION:RGD 4CY labeled with γ emitter nuclide is a potential tracer of tumor αvβ3 receptor scintigraphy.