Experimental Transplantation and Immunology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
Gene Ther. 2011 Jun;18(6):553-9. doi: 10.1038/gt.2010.169. Epub 2011 Jan 13.
Proto-oncogene activation caused by retroviral vector integration can cause malignancies in gene therapy trials. This has led investigators to search for less genotoxic vectors with minimal enhancer activity and a decreased risk of influencing neighboring chromosomal gene expression after integration. We previously showed that foamy virus (FV) vectors expressing the canine CD18 gene from an internal murine stem cell virus (MSCV) promoter could cure canine leukocyte adhesion deficiency (LAD). Here, we have repeated these studies using a FV vector expressing canine CD18 from a phosphoglycerate kinase (PGK) gene promoter. In vitro analysis showed that this vector did not contain an enhancer that activated neighboring genes, and it expressed CD18 efficiently in canine neutrophils and CD34+ cells. However, dogs that received hematopoietic stem cells transduced with the PGK-CD18 vector continued to suffer from LAD, and sometimes died prematurely of the disease. These studies show that the PGK promoter cannot effectively replace the MSCV promoter in CD18-expressing FV vectors, and they suggest that vectors containing a strong promoter-enhancer may be necessary for the treatment of human LAD.
逆转录病毒载体整合引起的原癌基因激活可能导致基因治疗试验中的恶性肿瘤。这促使研究人员寻找毒副作用较小的载体，其增强子活性最低，整合后影响邻近染色体基因表达的风险降低。我们之前曾报道，表达来自内部鼠干细胞病毒 (MSCV) 启动子的犬 CD18 基因的泡沫病毒 (FV) 载体可治愈犬白细胞黏附缺陷症 (LAD)。在此，我们使用表达来自磷酸甘油酸激酶 (PGK) 基因启动子的犬 CD18 的 FV 载体重复了这些研究。体外分析表明，该载体不含有激活邻近基因的增强子，并且它在犬中性粒细胞和 CD34+细胞中高效表达 CD18。然而，接受用 PGK-CD18 载体转导的造血干细胞的狗继续患有 LAD，并且有时过早死于该疾病。这些研究表明，PGK 启动子不能有效地替代 FV 载体中表达 CD18 的 MSCV 启动子，并且它们表明含有强启动子增强子的载体可能是治疗人类 LAD 所必需的。
