Department of Nuclear Medicine, Tianjin Medical University General Hospital, Anshan Road 154, Heping, Tianjin, People's Republic of China .
Cancer Biother Radiopharm. 2011 Aug;26(4):443-51. doi: 10.1089/cbr.2010.0908. Epub 2011 Jul 28.
Radioiodine is a routine therapy for differentiated thyroid cancers. In principle, undifferentiated thyroid cancers as well as nonthyroid cancers can concentrate and, thus, be treated with radioiodine after transfection with the human sodium iodide symporter (hNIS) gene. The human telomerase reverse transcriptase (hTERT) promoter is an effective tumor-specific promoter of gene expression and, thus, may be useful in targeted gene therapy of cancer.
We used hTERT promoter-modulated expression of the hNIS and human thyroperoxidase (hTPO) genes in an experimental model of radioiodine-based treatment of malignant glioma. Cells were cotransfected by adenovirus in which the hNIS gene had been coupled to the hTERT promoter and the hTPO gene had been coupled to the human cytomegalovirus (CMV) promoter (Ad-hTERT-hNIS and Ad-CMV-hTPO, respectively), and they were evaluated in cells thus transfecting transgene expression by western blots, (125)I uptake and influx, and clonogenecity after (131)I treatment.
After cotransfection with two adenovirus, cells showed about 31-34 times higher (125)I uptake than the control cells transfected with Ad-CMV-EGFP (enhanced green fluorescent protein) and almost 1.3-1.4 times higher (125)I uptake than cells only transfected with Ad-hTERT-hNIS. Western blots revealed two bands of ∼70 and 110 kDa, respectively. The in vitro clonogenic assay indicated that, after exposure to 100-1000 μCi of (131)I-iodide for 12 hours, 91%-94% of cells cotransfected with the hNIS and hTPO genes, 88%-93% of cells transfected with the hNIS gene, and only 62%-68% of control (nontransfected) cells were killed.
The experiments demonstrated that an effective therapy of (131)I was achieved in malignant glioma cell lines after induction of tumor-specific iodide uptake activity by the hTERT promoter-directed NIS expression in vitro. Cotransfection of the hNIS and hTPO genes can lead to longer retention of radioiodide, but did not increase cell killing over that achieved with transfection with the hNIS gene alone.
放射性碘是分化型甲状腺癌的常规治疗方法。原则上，未分化型甲状腺癌以及非甲状腺癌在转染人钠碘同向转运体（hNIS）基因后可以浓缩并因此用放射性碘进行治疗。人端粒酶逆转录酶（hTERT）启动子是一种有效的肿瘤特异性基因表达启动子，因此可能对癌症的靶向基因治疗有用。
我们使用 hTERT 启动子调节放射性碘治疗恶性胶质瘤的实验模型中 hNIS 和人甲状腺过氧化物酶（hTPO）基因的表达。细胞通过腺病毒共转染，其中 hNIS 基因与 hTERT 启动子相连，hTPO 基因与人类巨细胞病毒（CMV）启动子相连（分别为 Ad-hTERT-hNIS 和 Ad-CMV-hTPO），并用 Western blot、（125）I 摄取和流入以及（131）I 处理后的集落形成能力来评估转染细胞中外源基因的表达。
共转染两种腺病毒后，与转染 Ad-CMV-EGFP（增强型绿色荧光蛋白）的对照细胞相比，细胞的（125）I 摄取量高约 31-34 倍，与仅转染 hTERT-hNIS 的细胞相比，（125）I 摄取量高约 1.3-1.4 倍。Western blot 显示两条约 70 和 110 kDa 的条带。体外集落形成试验表明，在暴露于 100-1000 μCi（131）I-碘化物 12 小时后，共转染 hNIS 和 hTPO 基因的细胞 91%-94%、转染 hNIS 基因的细胞 88%-93%，而非转染（未转染）细胞仅 62%-68%被杀死。
实验证明，在体外通过 hTERT 启动子指导的 NIS 表达诱导肿瘤特异性碘摄取活性后，恶性胶质瘤细胞系中实现了有效的（131）I 治疗。hNIS 和 hTPO 基因的共转染可以导致放射性碘的更长保留，但与单独转染 hNIS 基因相比，并未增加细胞杀伤。
