核素示踪反义寡核苷酸在荷人淋巴瘤裸鼠中的分布及显像研究

Biodistribution and Imaging of Radionuclide Tracing Antisense Oligonucleotides in Nude Mice Bearing Human Lymphoma

目的研究125I标记反义寡核苷酸在正常小鼠内的生物分布,比较脂质体介导131I标记正义及反义寡核苷酸在荷人淋巴瘤裸鼠体内的显像,以探讨核素标记的ASON作为反义显像剂及反义治疗药物的可能性。方法通过氯胺-T法进行125I与131I标记含酪胺的18聚体寡核苷酸,制作荷瘤裸鼠模型,将148kBq125I标记反义寡核苷酸(2μg～3μg),尾静脉注入正常小鼠,于不同时间处死小鼠,测定不同组织及标准源的放射性计数。荷瘤裸鼠瘤内注入脂质体介导3.33MBq131I标记反义寡核苷酸(7μg～9μg),分别与注射后不同时间进行SPECT显像,以脂质体介导正义寡核苷酸作为对照,24h显像后处死全部裸鼠,取出血液、重要器官和肿瘤组织,测定各组织的放射性计数,并记算肿瘤与非肿瘤组织T/NT)比值。结果125I标记反义寡核苷酸注入正常小鼠体内后1h,各脏器达高峰,24h基本清除。肝、胃和肠放射性分布最高,骨、肌肉、脑中放射性分布较少。荷瘤裸鼠瘤内注入脂质体介导的131I标记反义寡核苷酸后立即用SPECT成像仅见肿瘤部位,1、2h成像可见示踪剂从肿瘤到腹腔,24h仍见肿瘤显像。比较24h正义组与反义组肿瘤的%ID/g、肿瘤/血液、肿瘤/肌肉,差异有统计学意义。结论131I标记ASON对淋巴瘤肿瘤组织有很强的特异性,可用于淋巴瘤反义显像和反义治疗的研究,但仍需进行大量的临床应用前研究。

Objective To investigate the possibility of using radioiodine labeled FR antisense oligonucleotides （ASON） as an imaging agent or antisense therapeutic radiopharmaceuticals in lymphoma. Methods A 18-mer oligonucleotides with a tyramine group was labeled by ^125I and ^131I using the chloramine T method and than made nude medal.Normal mice were injected via a tail vein with 148 kBq （4 μ Ci） ^125I-FR- antisense oligonucleotide （ASON）（2-3 μ g）. Animals were sacrificed at 1,2,4 and 24h and tissue samples were studied. DMRIE-C-mediated ^131I-FR-ASON and ^131I labeled sense oligonucleotides were injected intratumorally tumor-bearing BALB/c mice. Biodistribution was monitored by sequential scintigraphy and organ radioactivity at 24h after injection. Results The 5＇tyramine group allowed specific and stable radiolabelling of the ASON with radioiodine.The radioactivity reached its peak at l h after injection, and then decreased rapidly in normal mice after intravenous administration of ^125I-FR-ASON. When ^131I-FR-ASON injected intratumorally into mice grafted with Narnalwa cell line, images show tracer accumulate in tumor. Oonclusion Radiolabeled Ig FR-ASON showed high specificity in V 1 family B-cell lymphoma, and it should be considered further for nuclear medicine imaging application and radionuclide antisense therapy.