Leukemias following retroviral transfer of multildrug resistance 1 (MDR1) are driven by combinatorial insertional mutagenesis
Leukemias following retroviral transfer of multildrug resistance 1 (MDR1) are driven by combinatorial insertional mutagenesis
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DOI：
10.1182/blood-2004-11-4535
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发表时间：
2005-06-01
期刊：
影响因子：
20.3
通讯作者：
Baum, C
中科院分区：
文献类型：
--
作者：
Modlich, U;Kustikova, OS;Baum, C
先前的研究已经证明了在多药耐药1（MDR1）cDNA的高拷贝逆转录病毒基因转移后小鼠的白血病并发症，MDR1 cDNA编码在造血干细胞中表达的膜定位外排泵。相反，在探索MDR1基因转移至细胞系、小鼠、犬、非人灵长类动物和人类受试者的许多其他研究中，未观察到此类并发症或MDR1相关的造血改变。在这里，我们表明，白血病与逆转录病毒表达的MDR1依赖于高载体剂量，并涉及选择与组合插入突变的原癌基因或其他信号基因的克隆。与正常的长期再生造血细胞的插入模式相比，这种命中在白血病克隆中过度代表，指出因果作用。在荧光蛋白高拷贝逆转录病毒基因转移后出现的白血病中也观察到类似的插入位点群。光谱核型分析表明，额外的染色体易位的情况下，一个子集，指示继发性遗传不稳定。我们还表明，插入突变体可以在移植前在体外扩增。基于这些发现，我们建议使用临床前剂量递增研究来定义逆转录病毒转基因递送的治疗指数。
Previous studies have demonstrated leukemic complications in mice after high-copy retroviral gene transfer of the multidrug resistance 1 (MDR1) cDNA, encoding a membrane-located efflux pump expressed in hematopoietic stem cells. In contrast, no such complications or MDR1 associated alterations of hematopoiesis were observed in numerous other studies exploring MDR1 gene transfer into cell lines, mice, dogs, nonhuman primates, and human subjects. Here, we show that leukemias associated with retroviral expression of MDR1 depend on high vector dose, and involve the selection of clones with combinatorial insertional mutagenesis of proto-oncogenes or other signaling genes. Compared with insertion patterns in normal long-term repopulating hematopoietic cells, such hits were over-represented in leukemic clones, pointing to a causal role. A similar constellation of insertion sites was also observed in a leukemia arising after high-copy retroviral gene transfer of a fluorescent protein. Spectral karyotyping demonstrated additional chromosomal translocations in a subset of cases, indicative of secondary genetic instability. We also show that insertional mutants can be amplified in vitro prior to transplantation. On the basis of these findings, we suggest the use of preclinical dose-escalation studies to define a therapeutic index for retroviral transgene delivery.