Wang Weijun, Tai Chien-Kuo, Kershaw Allan D, Solly Sounkary K, Klatzmann David, Kasahara Noriyuki, Chen Thomas C
Department of Neurosurgery, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
Neurosurg Focus. 2006 Apr 15;20(4):E25. doi: 10.3171/foc.2006.20.4.1.
The authors had previously reported on a replication-competent retrovirus (RCR) that has been demonstrated to be stable, capable of effective transduction, and able to prolong survival in an intracranial tumor model in nude mice. The purpose of this study was further investigation of this gene therapy option.
The transduction efficiency of RCR in RG2, an immunocompetent intracranial tumor model, was tested in Fischer 344 rats. The immune response to the RCR vector was expressed by the quantification of CD4, CD8, and CD11/b in tumors. The pharmaceutical efficacy of the suicide gene CD in converting prodrug 5-fluorocytosine (5-FC) to 5-fluorouracil (5-FU) was measured using fluorine-19 nuclear magnetic resonance (19F-NMR) spectroscopy. Animal survival data were plotted on Kaplan-Meier survival curves. Finally, the biodistribution of RCR was determined using quantitative real-time polymerase chain reaction (RT-PCR) for the detection of retroviral env gene. There was no evidence of viral transduction in normal brain cells. Neither severe inflammation nor immunoreaction occurred after intracranial injection of RCR-green fluorescent protein compared with phosphate-buffered saline (PBS). The 19F-NMR spectroscopy studies demonstrated that RCR-CD was able to convert 5-FC to 5-FU effectively in vitro. The infection of RG2 brain tumors with RCR-CD and their subsequent treatment with 5-FC significantly prolonged survival compared with that in animals with RG2 transduced tumors treated with PBS. In contrast to the nude mouse model, evidence of virus dissemination to the systemic organs after intracranial injection was not detected using RT-PCR.
The RCR-mediated suicide gene therapy described in this paper effectively transduced malignant gliomas in an immunocompetent in vivo rodent model, prolonging survival, without evidence of severe intracranial inflammation, and without local transduction of normal brain cells or systemic organs.
作者之前报道了一种具有复制能力的逆转录病毒（RCR），已证明其具有稳定性，能够有效转导，并能延长裸鼠颅内肿瘤模型的生存期。本研究的目的是进一步研究这种基因治疗方案。
在Fischer 344大鼠中测试RCR在具有免疫活性的颅内肿瘤模型RG2中的转导效率。通过对肿瘤中CD4、CD8和CD11/b进行定量来表达对RCR载体的免疫反应。使用氟-19核磁共振（19F-NMR）光谱法测定自杀基因CD将前药5-氟胞嘧啶（5-FC）转化为5-氟尿嘧啶（5-FU）的药物疗效。将动物生存数据绘制在Kaplan-Meier生存曲线上。最后，使用定量实时聚合酶链反应（RT-PCR）检测逆转录病毒env基因来确定RCR的生物分布。在正常脑细胞中未发现病毒转导的证据。与磷酸盐缓冲盐水（PBS）相比，颅内注射RCR-绿色荧光蛋白后未发生严重炎症或免疫反应。19F-NMR光谱研究表明，RCR-CD在体外能够有效地将5-FC转化为5-FU。与用PBS处理的RG2转导肿瘤动物相比，用RCR-CD感染RG2脑肿瘤并随后用5-FC治疗可显著延长生存期。与裸鼠模型不同，使用RT-PCR未检测到颅内注射后病毒扩散到全身器官的证据。
本文所述的RCR介导的自杀基因疗法在具有免疫活性的体内啮齿动物模型中有效转导恶性胶质瘤，延长生存期，没有严重颅内炎症的证据，也没有正常脑细胞或全身器官的局部转导。
