Evaluation of the therapeutic effect of replication-competent adenovirus on thyroid carcinomas

在体外和体内研究了条件复制腺病毒对甲状腺癌的治疗作用。(1)分化的甲状腺癌——我们构建了复制型腺病毒（AdTgE1A），其中E1A基因（腺病毒复制不可或缺的基因）位于甲状腺球蛋白（Tg）启动子（甲状腺特异性启动子）的下游。AdTgElA感染导致表达Tg的分化甲状腺癌细胞中E1A的表达、病毒复制（子代产生）和细胞病变作用，而在其他不表达Tg的细胞中则没有。此外，我们的研究表明，AdTgE1A与其他基因疗法（包括表达自杀基因或细胞因子的腺病毒）联合使用的效果增强。(2)间变性甲状腺癌——为了实现p53突变腺病毒的细胞特异性复制，我们采用p53应答启动子的“基因失活策略”、Cre-LoxP系统和双重感染方法。这种策略在体外效果很好，但在体内效果不太好，可能是因为体内传染性较低。由于p53启动子在293细胞中并非完全沉默，因此不可能构建包含所有成分的单个腺病毒。

We studied the therapeutic effect of the conditionally replication competent adenovirus on thyroid carcinomas in vitro and in vivo.(1) Differentiated thyroid carcinomas - We constructed the replicative adenovirus (AdTgE1A) in which the E1A gene, an indispensable gene for adenovirus replication, is placed downstream of thyroglobulin (Tg) promoter, a thyroid-specific promoter. Infection of AdTgElA led to E1A expression, virus replication (progeny production) and cytopathic effect in differentiated thyroid carcinoma cells expressing Tg, but not in other cells expressing no Tg. Furthermore, our studies demonstrated the enhanced effect of the combination of AdTgE1A and other gene therapies, including adenoviruses expressing a suicide gene or a cytokine.(2) Anaplastic thyroid carcinomas - To achieve p53-mutated cell-specific replication of adenovirus, we used "gene inactivation strategy" with p53-responseive promoter, Cre-LoxP system and double infection method. This strategy worked very well in vitro, but not so well in vivo, presumably because of low in vivo infectivity. Construction of a single adenovirus containing all the components was found impossible, since p53 promoter is not absolutely silent in 293 cells.