Galmarini Carlos María, Clarke Marilyn L, Santos Cheryl L, Jordheim Lars, Perigaud Christian, Gosselin Gilles, Cros Emeline, Mackey John R, Dumontet Charles
INSERM 590, Laboratoire de Cytologie Analytique, Faculté de Médecine Rockefeller, Lyon, France.
Int J Cancer. 2003 Oct 20;107(1):149-54. doi: 10.1002/ijc.11339.
Adequate intracellular concentrations of ara-CMP, the monophosphorylated derivative of ara-C, are essential for its cytotoxicity. The critical step for ara-CMP formation is intracellular phosphorylation of ara-C by deoxycytidine kinase (dCK). A common nucleoside resistance mechanism is mutation affecting the expression or the specificity of dCK. We describe the ability of a tert-butyl S-acyl-thioethyl (SATE) derivative of ara-CMP (UA911) to circumvent ara-C resistance in a dCK-deficient human follicular lymphoma cell line (RL-G). The RL-G cell line was produced by continuous exposure to gemcitabine and displayed low dCK mRNA and protein expression that conferred resistance both to ara-C (2,250-fold) and to gemcitabine (2,092-fold). RL-G cells were able to take up the UA911 pronucleotide by diffusion and metabolize it to the corresponding ara-CMP and ara-CTP nucleotides, exhibiting a 199-fold reduction in resistance ratios, and a similar cell cycle arrest to the parental RL-7 cells. Exposures to 10, 50 or 100 microM concentrations of UA911 produced 160 +/- 7, 269 +/- 8 and 318 +/- 62 pmol ara-CTP/mg protein in RL-7 cells, and 100 +/- 12, 168 +/- 10 and 217 +/- 39 pmol ara-CTP/mg protein in RL-G cells, respectively. Exposure of RL-G cells to underivatized, radiolabeled ara-C produced no detectable amounts of the active triphosphate metabolites. We conclude that the UA911 pronucleotide is capable of overcoming dCK-mediated resistance. This result can be attributed to the unique cellular metabolism of the SATE pronucleotides giving rise to the intracellular delivery of ara-CMP to dCK-deficient cells.
阿糖胞苷单磷酸化衍生物阿糖胞苷一磷酸（ara - CMP）在细胞内达到足够浓度对其细胞毒性至关重要。阿糖胞苷一磷酸形成的关键步骤是脱氧胞苷激酶（dCK）对阿糖胞苷进行细胞内磷酸化。一种常见的核苷耐药机制是影响dCK表达或特异性的突变。我们描述了阿糖胞苷一磷酸的叔丁基S - 酰基硫代乙酯（SATE）衍生物（UA911）在dCK缺陷的人滤泡性淋巴瘤细胞系（RL - G）中规避阿糖胞苷耐药的能力。RL - G细胞系是通过持续暴露于吉西他滨产生的，其dCK mRNA和蛋白表达水平低，对阿糖胞苷（2250倍）和吉西他滨（2092倍）均具有耐药性。RL - G细胞能够通过扩散摄取UA911前体药物并将其代谢为相应的阿糖胞苷一磷酸和阿糖胞苷三磷酸核苷酸，耐药比降低了199倍，并且细胞周期阻滞情况与亲代RL - 7细胞相似。暴露于10、50或100微摩尔浓度的UA911时，RL - 7细胞中分别产生160±7、269±8和318±62皮摩尔阿糖胞苷三磷酸/毫克蛋白，RL - G细胞中分别产生100±12、168±10和217±39皮摩尔阿糖胞苷三磷酸/毫克蛋白。将RL - G细胞暴露于未衍生化的放射性标记阿糖胞苷时，未检测到活性三磷酸代谢产物。我们得出结论，UA911前体药物能够克服dCK介导的耐药性。这一结果可归因于SATE前体药物独特的细胞代谢，从而使阿糖胞苷一磷酸能在细胞内递送至dCK缺陷细胞。
