Chen Libo, Altmann Annette, Mier Walter, Eskerski Helmut, Leotta Karin, Guo Lihe, Zhu Ruisen, Haberkorn Uwe
Department of Nuclear Medicine, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China.
J Nucl Med. 2006 May;47(5):854-62.
We investigated the feasibility of radioiodine therapy targeting hepatoma cells (MH3924A) by tissue-specific expression of the human sodium/iodide symporter (hNIS) gene directed by the murine albumin enhancer and promoter (mAlb).
The cell-specific transcriptional activity of mAlb was examined by a luciferase assay in several transiently transfected cell lines. MH3924A cells were stably transfected with the recombinant retroviral vector, in which hNIS complementary DNA expression was driven by mAlb and coupled to hygromycin resistance gene using an internal ribosomal entry site (IRES). Functional hNIS expression in hepatoma cells was confirmed by an iodide uptake assay. In imaging studies, the tumor-bearing ACI rats were intravenously injected with (131)I and imaged with a gamma-camera. Biodistribution was studied at 30 min and at 1, 3, 6, and 25 h after injection of (131)I. Toxic effects of (131)I on hepatoma cells were studied in vitro and in vivo.
Stably transfected MH3924A cells concentrated (125)I up to 240-fold higher than the wild-type cells. The iodide uptake in stably transfected cells was inhibited by ouabain and sodium perchlorate but increased by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. An in vitro clonogenic assay revealed an 86% decrease in colony number in stably transfected cells after exposure to 3.7 MBq/mL of (131)I and only about 8% in hNIS-negative control cells. Furthermore, the in vivo study showed intense tracer accumulation in hNIS-expressing tumors after administration of (131)I. At 3 h after intraperitoneal injection, the transfected tumors accumulated (131)I 19.2-fold higher than the parental tumors in a biodistribution study. Moreover, administration of a therapeutic dose of (131)I resulted in an inhibition of hNIS-expressing tumor growth, whereas control tumors continued to increase in size.
A therapeutic effect of (131)I on hepatoma cells in vitro and in vivo has been demonstrated after tumor-specific iodide uptake induced by mAlb-directed hNIS gene expression. Because a stable transformed cell line has been used in these experiments, the clinical potential of this strategy must be evaluated after in vivo transfection of hepatoma cells.
我们研究了通过鼠白蛋白增强子和启动子（mAlb）指导的人钠/碘同向转运体（hNIS）基因的组织特异性表达来靶向肝癌细胞（MH3924A）进行放射性碘治疗的可行性。
通过荧光素酶测定法在几种瞬时转染的细胞系中检测mAlb的细胞特异性转录活性。用重组逆转录病毒载体稳定转染MH3924A细胞，其中hNIS互补DNA的表达由mAlb驱动，并使用内部核糖体进入位点（IRES）与潮霉素抗性基因偶联。通过碘摄取试验证实肝癌细胞中功能性hNIS的表达。在成像研究中，给荷瘤ACI大鼠静脉注射（131）I并用γ相机成像。在注射（131）I后30分钟以及1、3、6和25小时研究生物分布。在体外和体内研究了（131）I对肝癌细胞的毒性作用。
稳定转染的MH3924A细胞对（125）I的摄取比野生型细胞高240倍。哇巴因和高氯酸钠抑制稳定转染细胞中的碘摄取，但4,4'-二异硫氰基芪-2,2'-二磺酸可增加碘摄取。体外克隆形成试验显示，暴露于3.7 MBq/mL的（131）I后，稳定转染细胞中的集落数减少86%，而hNIS阴性对照细胞中仅减少约8%。此外，体内研究显示给予（131）I后，hNIS表达肿瘤中有强烈的示踪剂积聚。在生物分布研究中，腹腔注射后3小时，转染肿瘤对（131）I的摄取比亲本肿瘤高19.2倍。此外，给予治疗剂量的（131）I可抑制hNIS表达肿瘤的生长，而对照肿瘤继续增大。
在mAlb指导的hNIS基因表达诱导肿瘤特异性碘摄取后，已证明（131）I在体外和体内对肝癌细胞具有治疗作用。由于在这些实验中使用了稳定转化的细胞系，该策略的临床潜力必须在肝癌细胞体内转染后进行评估。
