Lan K H, Kanai F, Shiratori Y, Ohashi M, Tanaka T, Okudaira T, Yoshida Y, Hamada H, Omata M
Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Cancer Res. 1997 Oct 1;57(19):4279-84.
Previously, we reported that adenoviral vectors carrying the carcinoembryonic antigen (CEA) promoter sequences to direct the Echerichia coli beta-galactosidase gene (AdCEA-lacZ) or cytosine deaminase (CD) gene (AdCEA-CD) confer selective gene expression on a CEA-positive gastric cancer cell line (MKN45) in vitro. Here, adenovirus-mediated tumor-specific gene therapy for CEA-positive gastric carcinoma in vivo was investigated. Using an animal model with i.p. disseminated MKN45 tumors, adenovirus-mediated tumor-specific transgene expression and therapeutic efficacy were analyzed. After an i.p. injection of AdCEA-lacZ, beta-galactosidase activity was confined to tumor xenografts. Moreover, CD mRNA was expressed exclusively in MKN45 tumor xenografts after infection with AdCEA-CD, despite the fact that an adenovirus-mediated transfer of CD DNA was detected in all tissues tested. In contrast, CD mRNA was detected not only in tumor xenografts but also in other organs of mice infected with AdCA-CD, in which CD gene expression is governed by an ubiquitous promoter. Suppression of tumor growth and prolongation of survival were noted in tumor-bearing mice treated with AdCEA-CD and 5-fluorocytosine (5FC) without observable adverse effects. In contrast, significant hepatic toxicity was noted in animals treated with AdCA-CD. These results reveal that the CEA promoter restricts CD gene expression to CEA-positive tumor cells in the adenoviral context in vivo, along with the beneficial therapeutic effects of 5FC treatment, suggesting the i.p. AdCEA-CD/5FC system may provide a novel approach to treatment of i.p. disseminated gastric cancer.
此前，我们报道了携带癌胚抗原（CEA）启动子序列以指导大肠杆菌β-半乳糖苷酶基因（AdCEA-lacZ）或胞嘧啶脱氨酶（CD）基因（AdCEA-CD）的腺病毒载体在体外可使CEA阳性胃癌细胞系（MKN45）实现选择性基因表达。在此，我们研究了腺病毒介导的体内CEA阳性胃癌肿瘤特异性基因治疗。利用腹腔播散性MKN45肿瘤的动物模型，分析了腺病毒介导的肿瘤特异性转基因表达和治疗效果。腹腔注射AdCEA-lacZ后，β-半乳糖苷酶活性局限于肿瘤异种移植瘤。此外，感染AdCEA-CD后，CD mRNA仅在MKN45肿瘤异种移植瘤中表达，尽管在所有检测组织中均检测到腺病毒介导的CD DNA转移。相比之下，在感染AdCA-CD（其中CD基因表达由普遍存在的启动子调控）的小鼠的肿瘤异种移植瘤以及其他器官中均检测到CD mRNA。在用AdCEA-CD和5-氟胞嘧啶（5FC）治疗的荷瘤小鼠中，观察到肿瘤生长受到抑制且生存期延长，且无明显不良反应。相比之下，用AdCA-CD治疗的动物出现了明显的肝毒性。这些结果表明，在体内腺病毒环境中，CEA启动子可将CD基因表达限制在CEA阳性肿瘤细胞中，同时5FC治疗具有有益的治疗效果，提示腹腔注射AdCEA-CD/5FC系统可能为腹腔播散性胃癌的治疗提供一种新方法。
