Hakkarainen Tanja, Hemminki Akseli, Curiel David T, Wahlfors Jarmo
Rational Drug Design Program, University of Helsinki, 00014 University of Helsinki, Helsinki, Finland.
Int J Mol Med. 2006 Oct;18(4):751-9.
The utility of conditionally replicative adenoviruses (CRAds) in cancer gene therapy is based on their ability to destroy tumor cells by oncolysis. However, in order to achieve adequate therapeutic response, CRAds have to spread through the tumor tissue by replication. Thus, to study the potency of these viruses to replicate and penetrate in tumors, we created a herpes simplex virus type 1 thymidine kinase-green fluorescent protein fusion gene (TK-GFP) encompassing CRAd (Ad5Delta24TK-GFP), whose tumor selectivity is mediated by a retinoblastoma (Rb)-binding site mutation. In addition, we evaluated the oncolytic efficacy of Ad5Delta24TK-GFP in combination with the TK/ganciclovir (GCV) system. Based on our results, Ad5Delta24TK-GFP replicates in cancer cells resulting in oncolysis and can efficiently penetrate into tumors. Additionally, the combination of GCV with Ad5Delta24TK-GFP augmented cell death in vitro but this was not observed in vivo: tumor growth was significantly reduced by oncolysis when compared to non-replicative virus (p<0.001), but administration of GCV did not significantly enhance oncolysis. This suggests that in certain conditions, TK/GCV-mediated cell killing may be counterproductive to replication and oncolysis, which on the other hand might be useful feature for clinical trials in case of replication-associated toxicity.
条件性复制腺病毒（CRAds）在癌症基因治疗中的效用基于其通过溶瘤作用破坏肿瘤细胞的能力。然而，为了实现足够的治疗反应，CRAds必须通过复制在肿瘤组织中扩散。因此，为了研究这些病毒在肿瘤中复制和渗透的能力，我们构建了一种包含CRAd（Ad5Delta24TK-GFP）的单纯疱疹病毒1型胸苷激酶-绿色荧光蛋白融合基因（TK-GFP），其肿瘤选择性由视网膜母细胞瘤（Rb）结合位点突变介导。此外，我们评估了Ad5Delta24TK-GFP与TK/更昔洛韦（GCV）系统联合使用时的溶瘤效果。基于我们的结果，Ad5Delta24TK-GFP在癌细胞中复制导致溶瘤，并能有效渗透到肿瘤中。此外，GCV与Ad5Delta24TK-GFP联合使用在体外增强了细胞死亡，但在体内未观察到这种情况：与非复制型病毒相比，溶瘤作用显著降低了肿瘤生长（p<0.001），但给予GCV并未显著增强溶瘤作用。这表明在某些情况下，TK/GCV介导的细胞杀伤可能对复制和溶瘤产生反作用，而另一方面，在存在与复制相关的毒性的情况下，这可能是临床试验中的一个有用特征。
