saRNA激活hNIS和hTPO基因介导肝癌核素显像与治疗的机制研究

Liver cancer is the fouth most frequently diagnosed cancer but the second most frequent cause of cancer death in China. Surgical resection remains the curative therapy for LC so far. However, the patients who have local recurrence or distant metastasis after curative nephrectomy are susceptible to have a cancer-related death.LC cells are resistant to express sodium iodide transporter (NIS) gene and thyroid peroxidase (TPO) gene, even if they are the molecular basis of 131I treatment for differentiated thyroid cancer metastases. Previous studies have shown that it has potential value for the treatment of liver cancer if we use NIS gene transfect the liver cancer cell which can promote liver cells intake radioactive iodine.But the molecular weight of NIS gene so large and the transfection rate so low that can’t be synthesized by chemical methods, and iodine in liver cancer cell remains short retention time, therefore the radiotherapy effect on liver cancer cells is weakly. Early We have adopt small activate RNA (saRNA) acrivate endogenous NIS gene in liver cancer cells to verify that can promote liver cancer cells to intake radioactive iodine. Most impotant of all, saRNA has only 21 base pairs, which makes synthesis and mass production easily. In according to above, we get a hypothesis that there is a success treatment for liver cancer metastasis, if we adopt saRNA activate endogenous NIS and TPO gene of liver cancer cells, transfect those, and upgrade the expression level of hTPO and hNIS genes to promote liver cancer cells intake and strand the radioactive iodine.

我国肝癌死亡率为全国恶性肿瘤的第二位，肝癌高致死率的根本原因是复发和转移，临床上仍缺乏有效手段。钠碘转运体（ NIS）和甲状腺过氧化物酶(TPO)基因是131I治疗分化型甲状腺癌转移灶的分子基础，但肝癌细胞NIS和TPO基因不表达，无法实现131I靶向治疗。研究报道用NIS基因转染肝癌细胞，可促进肝癌细胞摄取碘。但所用外源性NIS基因分子量大，不能化学合成，且碘在细胞内滞留时间短。课题组前期用小激活RNA（ saRNA）激活肝癌细胞NIS基因，促进其摄取碘，而saRNA仅为21碱基对，易合成和批量生产。本研究拟采用saRNA转染肝癌细胞，激活肝癌细胞的内源性NIS和TPO基因的表达水平，促进肝癌细胞摄取和滞留碘，以期实现131I靶向治疗肝癌转移灶的目的。

我国肝癌死亡率为全国恶性肿瘤的第二位，肝癌高致死率的根本原因是复发和转移，临床上仍缺乏有效手段。钠碘转运体（ NIS）和甲状腺过氧化物酶(TPO)基因是131I治疗分化型甲状腺癌转移灶的分子基础，但肝癌细胞NIS和TPO基因不表达，无法实现131I靶向治疗。研究报道用NIS基因转染肝癌细胞，可促进肝癌细胞摄取碘。但所用外源性NIS基因分子量大，不能化学合成，且碘在细胞内滞留时间短。课题组前期用小激活RNA（saRNA）激活肝癌细胞NIS基因，促进其摄取碘，而saRNA仅为21碱基对，易合成和批量生产。本研究设计并合成了多条分别靶向hNIS和hTPO基因的saRNA序列，通过分子生物学实验筛选了可以有效上调hNIS和hTPO基因表达水平的saRNA序列，并通过系列分子生物学、细胞学和动物实验，验证了saRNA上调hNIS和hTPO基因表达水平的效率，及其介导肝癌细胞摄取放射性131I的能力和抑瘤作用，获取了saRNA调控NIS基因、saRNA调控TPO基因、saRNA转染肝癌细胞后的共聚焦成像、saRNA上调TPO表达水平、NIS-saRNA和TPO-saRNA联合转染介导核素摄取、131I的体内抑瘤作用等一系列关键数据。对于非甲状腺源肿瘤，至今的研究都是通过转染外源性DNA的方法调控hNIS和hTPO基因的表达，本研究采用具有靶向性saRNA通过RNAa技术激活瘤细胞内源性hNIS和hTPO基因，并通过上调hNIS和hTPO基因表达水平，促进癌细胞摄取放射性核素131I，达到对肿瘤的放射内照射治疗效果。