Antitumor efficacy of a dual-therapeutic-gene expressing adenovirus against bladder cancer

同时表达野生型p53和抗erbB 2核酶的腺病毒载体（Ad-p53/erbB 2 Rz）对人膀胱癌细胞的抗肿瘤效果进行了评价。腺病毒感染可充分调节靶基因及其编码蛋白的表达，并呈剂量依赖性抑制细胞生长。该病毒的治疗功效上级于表达单一治疗基因的其它对照病毒，即，p53或erbB 2核酶，当病毒滴度相同时，即使这些病毒组合使用时，也是如此。减少腺病毒的数量可以降低载体相关的非特异性细胞毒性，提高腺病毒对膀胱癌细胞的感染性是提高治疗效果的关键。柯萨奇-腺病毒受体（CAR）在腺病毒感染中起重要作用，有报道称CAR在高级别膀胱癌中表达降低。在几种膀胱癌细胞系中评估CAR表达和腺病毒感染性，并且根据培养细胞的条件观察到CAR的不稳定表达谱和不稳定的腺病毒感染性。这些现象与传代次数和细胞密度密切相关。然后使用纤维突变腺病毒（Ad 5/F35）来克服这种不稳定的腺病毒对膀胱癌细胞的感染性。在Ad 5/F35的感染中不需要CAR表达，并且CD 46被揭示为该病毒的受体。在几种膀胱癌细胞系中评估了CD 46的表达，并且在大多数细胞系中证明了稳定的强表达，而不像CAR表达。Ad 5/F35在大多数膀胱癌细胞中的感染性上级Ad 5，尤其是在高级别肿瘤中。该腺病毒载体有望在膀胱癌基因治疗中发挥重要作用。

Antitumor efficacy of an adenoviral vector (Ad-p53/erbB2Rz), which simultaneously expresses wild-type p53 and anti-erbB2 ribozyme, was evaluated against human bladder cancer cells. Expression of the targeted genes and their encoded proteins was sufficiently modulated by the adenoviral infection, and cell growth was inhibited dose-dependently. The therapeutic efficacy of this virus was superior to other control viruses those express single therapeutic genes, i.e., p53 or erbB2 ribozyme, when the amount of viral titer was same, even when these viruses were used in combination. Decreasing the amount of viruses resulted in reduced nonspecific vector-related cytotoxicity.For enhancing the therapeutic efficacy, improvement of adenoviral infectivity to bladder cancer cells was aimed. Cocsackie-Adenovirus Receptor (CAR) plays crucial role in adenoviral infection, and the decreased expression of CAR in high-grade bladder cancer has been reported. CAR expression and adenoviral infectivity were evaluated in several bladder cancer cell lines, and unstable expression profile of CAR and unsteady adenoviral infectivity were observed depending on the condition of cultured cells. These phenomenons were related strongly to passage numbers and density of the cells. Fiber-mutant adenovirus (Ad5/F35) was then employed for overcoming this unstable adenoviral infectivity to bladder cancer cells. CAR expression is not required in infection of Ad5/F35, and CD46 was revealed as the receptor of this virus. The expression CD46 was evaluated in several bladder cancer cell lines, and stable strong expression was demonstrated in most cell lines unlike CAR expression. The infectivity of Ad5/F35 was superior to Ad5 in most bladder cancer cells, especially in high-grade tumors. This fiber-mutant adenoviral vector might have strong impact on bladder cancer gene therapy.