Two distinct molecular mechanisms underlying cytarabine resistance in human leukemic cells
Two distinct molecular mechanisms underlying cytarabine resistance in human leukemic cells
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DOI：
10.1158/0008-5472.can-07-5528
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发表时间：
2008-04-01
期刊：
影响因子：
11.2
通讯作者：
Gros, Philippe
中科院分区：
文献类型：
--
作者：
Cai, Jie;Damaraju, Vijaya L.;Gros, Philippe
为了了解细胞对核苷类似物阿糖胞苷（1-β-D-阿拉伯呋喃糖基胞嘧啶，AraC）耐药的机制，通过在不同浓度的AraC中逐步选择获得了两种人白血病细胞系CCRF-CEM的耐药衍生物。CEM/4XAraC细胞对AraC的耐药性较低，而CEM/20 XAraC细胞对AraC的耐药性较高。两种细胞系显示出对多种细胞毒性核苷类似物的交叉耐药性的相似模式，除了CEM/20 xAraC细胞对5-氟尿苷和2-脱氧-5-氟尿苷保持敏感。两种细胞系均对5-氟尿嘧啶和多种天然产物药物敏感。尽管CEM/4XAraC和CEM/20 XAraC细胞都显示出[H-3]AraC的细胞内积累减少，但只有CEM/4xAraC细胞显示出用于评估核苷转运活性的[H-3]尿苷摄取减少。对已知参与核苷转运、外排和代谢的蛋白质编码基因进行了分析，以确定两种细胞系中是否存在突变。在CEM/4XAraC细胞中，在人平衡型核苷转运蛋白I（hENT 1; SLUM]）的每个等位基因处鉴定出独立突变，一个对应于外显子4中的单核苷酸变化，另一个是破坏外显子13剪接的复杂内含子突变。与CEM/20 XAraC细胞相反，CEM/4XAraC细胞不结合hENT 1/SLC 29 A1配体硝基苄基巯基嘌呤核糖核苷，并且缺乏可检测的hENT 1/SLC 29 A1蛋白。在CEM/20 XAraC细胞中，在脱氧胞苷激酶基因的每个等位基因处发现了独立的内含子突变，其损害外显子2和3的剪接。这些研究指出了白血病细胞中AraC抗性的至少两种不同机制。
To understand the mechanism of cellular resistance to the nucleoside analogue cytarabine (1-beta-D-arabinofuranosylcytosine, AraC), two resistant derivatives of the human leukemic line CCRF-CEM were obtained by stepwise selection in different concentrations of AraC. CEM/4XAraC cells showed low AraC resistance, whereas CEM/20XAraC cells showed high resistance. Both cell lines showed similar patterns of cross-resistance to multiple cytotoxic nucleoside analogues, with the exception that CEM/20xAraC cells remained sensitive to 5-fluorouridine and 2-deoxy-5-fluorouridine. Both cell lines were sensitive to 5-fluorouracil and to a variety of natural product drugs. Although both CEM/4XAraC and CEM/ 20XAraC cells displayed reduced intracellular accumulation of [H-3]AraC, only CEM/4xAraC cells showed reduced uptake of [H-3]uridine, which was used to assess nucleoside transport activities. Genes encoding proteins known to be involved in nucleoside transport, efflux, and metabolism were analyzed for the presence of mutations in the two cell lines. In CEM/4XAraC cells, independent mutations were identified at each allele of human equilibrative nucleoside transporter I (hENT1; SLUM]), one corresponding to a single-nucleotide change in exon 4, the other being a complex intronic mutation disrupting splicing of exon 13. In contrast to CEM/20XAraC cells, CEM/4XAraC cells did not bind the hENT1/SLC29A1 ligand nitrobenzylmercaptopurine ribonucleoside and lacked detectable hENT1/SLC29A1 protein. In CEM/20XAraC cells, independent intronic mutations impairing splicing of exons 2 and 3 were found at each allele of the deoxycytidine kinase gene. These studies point to at least two distinct mechanisms of AraC resistance in leukemic cells.