Brady Urological Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287-2101, USA.
Cancer Gene Ther. 2010 Aug;17(8):585-97. doi: 10.1038/cgt.2010.15. Epub 2010 May 7.
Conditionally replicating adenoviruses (CRAds) represent a promising modality for the treatment of neoplastic diseases, including Prostate Cancer. Selectively replicating viruses can be generated by placing a tissue or cancer-specific promoter upstream of one or more of the viral genes required for replication (for example, E1A, E1B). We have previously reported multiple cellular processes that can attenuate viral replication, which in turn compromises viral oncolysis and tumor kill. In this study, we investigated the importance of the cyclin-dependent kinase inhibitor p21/Waf-1, on viral replication and tumor growth. To our knowledge, this is the first report describing the importance of p21/Waf-1shRNA on the induction of an androgen responsive element (ARE) based promoter driving the E1A gene. As a proof of concept, the study emphasizes the use of RNA interference technology to overcome promoter weaknesses for tissue-specific oncolytic viruses, as well as the cellular inhibitor pathways on viral life cycle. Using RNA interference against p21/Waf-1, we were able to show an increase in viral replication and viral oncolysis of prostate cancer cells. Similarly, CRAd viruses that carry p21/Waf-1 shRNA (Ad5-RV004.21) were able to prevent tumor outgrowth that resulted in a marked increase in the mean survival time of tumor-bearing mice compared with CRAd without p21/Waf-1 shRNA (Ad5-RV004). In studies combining Ad5-RV004.21 with Adriamycin, a suprar-additive effect was observed only in CRAds that harbor shRNA against p21/Waf-1. Taken together, these findings of enhanced viral replication in prostate cancer cells by using RNA interference against the cdk inhibitor p21/Waf-1 have significant implications in the development of prostate-specific CRAd therapies.
条件复制型腺病毒（CRAd）是治疗肿瘤疾病（包括前列腺癌）的一种很有前途的方法。通过将组织或癌症特异性启动子置于一个或多个复制所需的病毒基因（例如 E1A、E1B）的上游，可以生成选择性复制的病毒。我们之前报道了多种可以减弱病毒复制的细胞过程，这反过来又会影响病毒的溶瘤作用和肿瘤杀伤作用。在这项研究中，我们研究了细胞周期蛋白依赖性激酶抑制剂 p21/Waf-1 对病毒复制和肿瘤生长的重要性。据我们所知，这是第一份描述 p21/Waf-1shRNA 对基于雄激素反应元件（ARE）的启动子驱动 E1A 基因的重要性的报告。作为一个概念验证，该研究强调了使用 RNA 干扰技术来克服组织特异性溶瘤病毒的启动子弱点，以及细胞抑制剂途径对病毒生命周期的影响。通过针对 p21/Waf-1 的 RNA 干扰，我们能够证明前列腺癌细胞中的病毒复制和溶瘤作用增加。同样，携带 p21/Waf-1shRNA 的 CRAd 病毒（Ad5-RV004.21）能够防止肿瘤生长，从而导致荷瘤小鼠的平均存活时间显著延长，与没有 p21/Waf-1shRNA 的 CRAd（Ad5-RV004）相比。在将 Ad5-RV004.21 与阿霉素联合使用的研究中，只有携带 p21/Waf-1shRNA 的 CRAd 观察到了超相加作用。综上所述，通过针对细胞周期蛋白依赖性激酶抑制剂 p21/Waf-1 使用 RNA 干扰来增强前列腺癌细胞中的病毒复制，这对开发前列腺特异性 CRAd 治疗具有重要意义。
