Tan Jian, Li Wei, Wang Peng
Department of Nuclear Medicine, General Hospital of Tianjin Medical University, Tianjin 300052, P. R. China.
Chin J Cancer. 2011 Aug;30(8):574-80. doi: 10.5732/cjc.010.10580.
Radioiodine is a routine therapy for differentiated thyroid cancers. Non-thyroid cancers can intake radioiodine after transfection of the human sodium iodide symporter (hNIS) gene. The human telomerase reverse transcriptase (hTERT) promoter, an excellent tumor-specific promoter, has potential value for targeted gene therapy of glioma. We used the hTERT promoter to drive the expression of the hNIS and human thyroid peroxidase (hTPO) gene as a primary step for testing the effects of radioiodine therapy on malignant glioma. The U87 and U251 cells were co-transfected with two adenoviral vectors, in which the hNIS gene had been coupled to the hTERT promoter and the hTPO gene had been coupled to the CMV promoter, respectively. Then, we performed Western blot, 125I intake and efflux assays, and clonogenic assay with cancer cells. We also did 99mTc tumor imaging of nude mice models. After co-transfection with Ad-hTERT-hNIS and Ad-CMV-hTPO, glioma cells showed the 125I intake almost 1.5 times higher than cells transfected with Ad-hTERT-hNIS alone. Western blots revealed bands of approximately 70 kDa and 110 kDa, consistent with the hNIS and hTPO proteins. In clonogenic assay, approximately 90% of co-transfected cells were killed, compared to 50% of control cells after incubated with 37 MBq of 131I. These results demonstrated that radioiodine therapy was effective in treating malignant glioma cell lines following induction of tumor-specific iodide intake by the hTERT promoter-directed hNIS expression in vitro. Co-transfected hNIS and hTPO genes can result in increased intake and longer retention of radioiodine. Nude mice harboring xenografts transfected with Ad-hTERT-NIS can take 99mTc scans.
放射性碘是分化型甲状腺癌的常规治疗方法。非甲状腺癌在转染人钠碘同向转运体（hNIS）基因后可摄取放射性碘。人端粒酶逆转录酶（hTERT）启动子是一种优良的肿瘤特异性启动子，对胶质瘤的靶向基因治疗具有潜在价值。我们使用hTERT启动子驱动hNIS和人甲状腺过氧化物酶（hTPO）基因的表达，作为测试放射性碘治疗对恶性胶质瘤效果的第一步。将U87和U251细胞分别与两种腺病毒载体共转染，其中hNIS基因与hTERT启动子相连，hTPO基因与CMV启动子相连。然后，我们对癌细胞进行了蛋白质免疫印迹、125I摄取和流出试验以及克隆形成试验。我们还对裸鼠模型进行了99mTc肿瘤成像。与单独转染Ad-hTERT-hNIS的细胞相比，在与Ad-hTERT-hNIS和Ad-CMV-hTPO共转染后，胶质瘤细胞的125I摄取几乎高出1.5倍。蛋白质免疫印迹显示出约70 kDa和110 kDa的条带，与hNIS和hTPO蛋白一致。在克隆形成试验中，与用37 MBq的131I孵育后的对照细胞的50%相比，约90%的共转染细胞被杀死。这些结果表明，在体外通过hTERT启动子指导的hNIS表达诱导肿瘤特异性碘摄取后，放射性碘治疗对恶性胶质瘤细胞系有效。共转染的hNIS和hTPO基因可导致放射性碘摄取增加和滞留时间延长。携带用Ad-hTERT-NIS转染的异种移植物的裸鼠可进行99mTc扫描。
