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

研究同时表达野生型p53和抗-erbB2核酶的重组腺病毒载体(Ad-P53/erbB2Rz)对人膀胱癌细胞的抗肿瘤作用。腺病毒感染可充分调控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。在病毒滴度相同的情况下，即使联合使用，该病毒的治疗效果也优于其他表达单一治疗基因的对照病毒，即p53或erbB2核酶。减少病毒数量可降低非特异性载体相关的细胞毒作用，为提高治疗效果，提高腺病毒对膀胱癌细胞的感染力。柯萨奇-腺病毒受体(CAR)在腺病毒感染中起重要作用，高级别膀胱癌中CAR的表达降低已有报道。在几种膀胱癌细胞系中检测了CAR的表达和腺病毒的感染性，根据培养细胞的不同，CAR的表达谱不稳定，腺病毒的感染性也不稳定。这些现象与传代次数和细胞密度密切相关。然后利用纤维突变型腺病毒(Ad5/F35)克服这种不稳定的腺病毒对膀胱癌细胞的感染性。Ad5/F35的感染不需要CAR的表达，CD46是该病毒的受体。CD46在几种膀胱癌细胞系中的表达与CAR表达不同，在大多数细胞系中表现出稳定的强表达。在大多数膀胱癌细胞中，Ad5/F35的感染性优于Ad5，尤其是在高级别肿瘤中。这种纤维突变型腺病毒载体可能对膀胱癌的基因治疗有很大的影响。

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.