Nyati M K, Symon Z, Kievit E, Dornfeld K J, Rynkiewicz S D, Ross B D, Rehemtulla A, Lawrence T S
Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109-0010, USA..
Gene Ther. 2002 Jul;9(13):844-9. doi: 10.1038/sj.gt.3301706.
Colorectal cancer can metastasize to the liver, but remain liver confined for years. A critical step in developing treatments for intrahepatic cancer involves assessment in an orthotopic intrahepatic model. The purpose of this study was to develop a noninvasive intrahepatic tumor model to study the efficacy of 5-flucytosine/yeast cytosine deaminase (5FC/yCD)-based gene therapy for liver tumors. Luciferase expressing human colorectal carcinoma (HT-29luc) cells were generated by retroviral infection and implanted in the left liver lobe of nude mice. The bioluminescence was measured every week for a period of 1 month, then animals were killed and tumors were measured by calipers. After we found a correlation between photon counts and tumor size, animals were implanted with tumors composed of either 0%, 10%, or 100% yCD/HT-29luc cells, and treated with 5FC. Tumor bioluminescence was measured during treatment and tumor histology examined at the time of death. We found that 5FC caused significant regression of yCD expressing tumors. Furthermore, visible tumors at the time of death, which emitted little bioluminescence, contained little or no viable tumor. We then developed an adenoviral vector for yCD. Intraperitoneal administration of adenovirus containing yCD led to the production of yCD enzyme within intrahepatic tumors. These results suggest that (1) intrahepatic cancer responds to 5FC when cells express yCD; (2) the luciferin-luciferase system permits non-invasive real time imaging of viable intrahepatic cancer; and (3) this system can be used to carry out gene therapy experiments using yCD adenovirus.
结直肠癌可转移至肝脏，但多年来一直局限于肝脏。开发肝内癌治疗方法的关键步骤之一涉及在原位肝内模型中进行评估。本研究的目的是建立一种非侵入性肝内肿瘤模型，以研究基于5-氟胞嘧啶/酵母胞嘧啶脱氨酶（5FC/yCD）的基因疗法对肝肿瘤的疗效。通过逆转录病毒感染产生表达荧光素酶的人结肠癌细胞（HT-29luc），并将其植入裸鼠的左肝叶。每周测量生物发光，持续1个月，然后处死动物，用卡尺测量肿瘤大小。在发现光子计数与肿瘤大小之间存在相关性后，给动物植入由0%、10%或100% yCD/HT-29luc细胞组成的肿瘤，并给予5FC治疗。在治疗期间测量肿瘤生物发光，并在处死时检查肿瘤组织学。我们发现5FC可使表达yCD的肿瘤显著消退。此外，死亡时可见的几乎不发出生物发光的肿瘤含有很少或没有存活肿瘤。然后我们开发了一种用于yCD的腺病毒载体。腹腔注射含yCD的腺病毒导致肝内肿瘤产生yCD酶。这些结果表明：（1）当细胞表达yCD时，肝内癌对5FC有反应；（2）荧光素-荧光素酶系统允许对存活的肝内癌进行非侵入性实时成像；（3）该系统可用于使用yCD腺病毒进行基因治疗实验。
