Li Xiong, Liu You-Hong, Zhang Yan-Ping, Zhang Shaobo, Pu Xinzhu, Gardner Thomas A, Jeng Meei-Huey, Kao Chinghai
Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA..
Clin Cancer Res. 2007 Sep 15;13(18 Pt 1):5463-73. doi: 10.1158/1078-0432.CCR-07-0342.
Recent studies showed that Fas ligand (FasL) induced apoptosis in tumor cells and suppressed the immune response in several types of tumors. However, the toxicity of FasL limited further administration. This study delivered FasL in prostate cancer cells using an improved prostate-restricted replicative adenovirus (PRRA), thereby improving the antitumor effect while decreasing systemic toxicity.
We designed a FasL-armed PRRA, called AdIU3, by placing adenoviral E1a and E4 genes, FasL cDNA, and E1b gene under the control of two individual PSES enhancers. Tissue-specific viral replication and FasL expression were analyzed, and the tumor killing effect of AdIU3 was investigated both in vitro and in vivo using androgen-independent CWR22rv s.c. models via local administration and bone models via systemic administration. The safety of systemic administration of AdIU3 was evaluated. AdCMVFasL, in which FasL was controlled by a universal cytomegalovirus (CMV) promoter, was used as a control.
AdIU3 enhanced FasL expression in prostate-specific antigen (PSA)/prostate-specific membrane antigen (PSMA)-positive cells but not in PSA/PMSA-negative cells. It induced apoptosis and killed PSA/PMSA-positive prostate cancer cells but spared normal human fibroblasts, hepatocytes, and negative cells. The increase in killing activity was confirmed to result in part from a bystander killing effect. Furthermore, AdIU3 was more effective than a plain PRRA in inhibiting the growth of androgen-independent prostate cancer xenografts and bone tumor formation. Importantly, systemic administration of AdIU3 resulted in undetectable toxicity, whereas the same doses of AdCMVFasL killed all mice due to multiviscera failure in 16 h.
AdIU3 decreased the toxicity of FasL by controlling its expression with PSES, with greatly enhanced prostate cancer antitumor efficacy. The results suggested that toxic antitumor factors can be delivered safely by a PRRA.
近期研究表明，Fas配体（FasL）可诱导肿瘤细胞凋亡，并抑制多种肿瘤的免疫反应。然而，FasL的毒性限制了其进一步应用。本研究利用改良的前列腺限制性复制腺病毒（PRRA）将FasL递送至前列腺癌细胞，从而在降低全身毒性的同时提高抗肿瘤效果。
我们通过将腺病毒E1a和E4基因、FasL cDNA以及E1b基因置于两个独立的前列腺特异性增强子（PSES）的控制之下，设计了一种携带FasL的PRRA，称为AdIU3。分析了组织特异性病毒复制和FasL表达，并通过局部给药在雄激素非依赖性CWR22rv皮下模型以及通过全身给药在骨模型中，体外和体内研究了AdIU3的肿瘤杀伤作用。评估了AdIU3全身给药的安全性。以由通用巨细胞病毒（CMV）启动子控制FasL的AdCMVFasL作为对照。
AdIU3增强了前列腺特异性抗原（PSA）/前列腺特异性膜抗原（PSMA）阳性细胞中的FasL表达，但在PSA/PMSA阴性细胞中未增强。它诱导凋亡并杀死PSA/PMSA阳性前列腺癌细胞，但对正常人成纤维细胞、肝细胞和阴性细胞无影响。杀伤活性增加被证实部分是由旁观者杀伤效应导致的。此外，AdIU3在抑制雄激素非依赖性前列腺癌异种移植瘤生长和骨肿瘤形成方面比普通PRRA更有效。重要的是，AdIU3全身给药未检测到毒性，而相同剂量的AdCMVFasL由于多脏器衰竭在16小时内导致所有小鼠死亡。
AdIU3通过用PSES控制FasL的表达降低了其毒性，同时大大增强了前列腺癌的抗肿瘤疗效。结果表明，毒性抗肿瘤因子可通过PRRA安全递送。
