Interaction of methotrexate with organic-anion transporting polypeptide 1A2 and its genetic variants
Interaction of methotrexate with organic-anion transporting polypeptide 1A2 and its genetic variants
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DOI：
10.1124/jpet.106.104364
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发表时间：
2006-08-01
影响因子：
3.5
通讯作者：
Giacomini, Kathleen M.
中科院分区：
文献类型：
--
作者：
Badagnani, Ilaria;Castro, Richard A.;Giacomini, Kathleen M.
甲氨蝶呤 (MTX) 用于治疗恶性疾病和自身免疫性疾病患者。该药物主要以原形通过尿液排泄，其净排泄通过主动分泌和重吸收过程发生。我们表征了 MTX 与人有机阴离子转运多肽转运蛋白 (OATP) 1A2 的相互作用，该蛋白在对 MTX 处置和毒性重要的组织中表达，例如肠、肾、肝和血脑屏障的内皮细胞。在表达 OATP1A2 的非洲爪蟾卵母细胞中，与未注射的卵母细胞相比，对模型底物 3-硫酸雌酮 (ES) 的摄取增强了 30 倍。表达 OATP1A2 的卵母细胞中的 MTX 摄取是饱和的（K-m = 457 +/- 118 muM；V-max = 17.5 +/- 4.9 pmol/卵母细胞/60 分钟）并且对细胞外 pH 敏感。也就是说，酸性 pH 值会刺激 MTX 的吸收高达 7 倍。在 270 个不同种族的 DNA 样本中发现了 7 种新的蛋白质改变变异。 OATP1A2 中的四个蛋白质改变变体表现出 ES 和/或 MTX 转运的改变。常见的变体，蛋白质参考序列 (p.) IIe13Thr，对于 ES 和 MTX 功能亢进，并且 ES 的 V-max 增加了 2 倍。常见的变体，p。 Glu172Asp 表现出 ES 和 MTX 最大转运能力降低。 p。 Arg168Cys 功能减退，p。 Asn277DEL 不起作用。由于其在远端小管的顶膜以及与 MTX 处置和毒性相关的组织中表达，这些发现表明 OATP1A2 可能在 MTX 的主动肾小管重吸收和 MTX 诱导的毒性中发挥作用。此外，OATP1A2 的遗传变异可能导致 MTX 处置和反应的变化。
Methotrexate (MTX) is used in patients with malignant and autoimmune diseases. This drug is primarily excreted unchanged in the urine, and its net excretion occurs via active secretory and reabsorptive processes. We characterized the interaction of MTX with human organic-anion transporting polypeptide transporter (OATP) 1A2, which is expressed in tissues important for MTX disposition and toxicity, such as the intestine, kidney, liver, and endothelial cells of the blood-brain barrier. In Xenopus laevis oocytes expressing OATP1A2, the uptake of the model substrate, estrone-3-sulfate (ES), was enhanced 30-fold compared with uninjected oocytes. MTX uptake in oocytes expressing OATP1A2 was saturable (K-m = 457 +/- 118 mu M; V-max = 17.5 +/- 4.9 pmol/oocyte/60 min) and sensitive to extracellular pH. That is, acidic pHs stimulated MTX uptake by as much as 7-fold. Seven novel protein-altering variants were identified in 270 ethnically diverse DNA samples. Four protein-altering variants in OATP1A2 exhibited altered transport of ES and/or MTX. The common variant, protein reference sequence (p.) IIe13Thr, was hyperfunctional for ES and MTX and showed a 2-fold increase in the V-max for ES. The common variant, p. Glu172Asp, exhibited reduced maximal transport capacity for ES and MTX. p. Arg168Cys was hypofunctional, and p. Asn277DEL was nonfunctional. Because of its expression on the apical membrane of the distal tubule and in tissues relevant to MTX disposition and toxicity, these findings suggest that OATP1A2 may play a role in active tubular reabsorption of MTX and in MTX-induced toxicities. Furthermore, genetic variation in OATP1A2 may contribute to variation in MTX disposition and response.