Loss of the high-affinity pentamidine transporter is responsible for high levels of cross-resistance between arsenical and diamidine drugs in African trypanosomes
Loss of the high-affinity pentamidine transporter is responsible for high levels of cross-resistance between arsenical and diamidine drugs in African trypanosomes
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DOI：
10.1124/mol.106.031351
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发表时间：
2007-04-01
影响因子：
3.6
通讯作者：
de Koning, Harry P.
中科院分区：
文献类型：
--
作者：
Bridges, Daniel J.;Gould, Matthew K.;de Koning, Harry P.
许多传染病的治疗受到耐药性的威胁。了解耐药机制与开发新药一样重要。我们已经调查了在非洲锥虫的联脒和三聚氰胺苯砷类药物之间的交叉耐药性的基础。我们诱导了高水平的戊烷脒耐药株系中没有tbat 1基因，该基因编码P2转运蛋白先前涉及药物摄取。我们分离的独立克隆，显示非常可观的交叉耐药性与美拉胂氧化物，但不氧化苯胂和减少摄取[H-3]pentamidine。特别是，高亲和力的喷他脒转运（HAPT 1）的活动是不存在的喷他脒适应线，而低亲和力的喷他脒转运（LAPT 1）的活动是不变的。亲本tbat 1（-/-）细胞系对氧化黑胂的裂解敏感，低浓度的喷他脒可抑制该过程，表明HAPT 1参与其中。在适应株系KO-B48中不存在这种戊脒可降解的裂解。同样地，荧光联脒4 ′，6-二脒基-2-苯基吲哚二盐酸盐的摄取在活KO-B48细胞中被大大延迟，并且对高达10 μ M的喷他脒的竞争不敏感。在KO-B48中未检测到布氏锥虫ATP结合盒转运蛋白TbMRPA的过表达。我们还表明，布氏冈比亚锥虫的实验室线，适应高水平的耐药性的三聚氰胺苯砷药物盐酸三聚氰胺（Cymelarsan），同样失去了TbAT 1和HAPT 1的活性，同时保留LAPT 1的活性。因此，似乎对喷他脒或砷类药物的抗性选择可以导致药物积累减少的相似表型，解释交叉抗性的发生。
Treatment of many infectious diseases is under threat from drug resistance. Understanding the mechanisms of resistance is as high a priority as the development of new drugs. We have investigated the basis for cross-resistance between the diamidine and melaminophenyl arsenical classes of drugs in African trypanosomes. We induced high levels of pentamidine resistance in a line without the tbat1 gene that encodes the P2 transporter previously implicated in drug uptake. We isolated independent clones that displayed very considerable cross-resistance with melarsen oxide but not phenylarsine oxide and reduced uptake of [H-3]pentamidine. In particular, the high-affinity pentamidine transport (HAPT1) activity was absent in the pentamidine-adapted lines, whereas the low affinity pentamidine transport (LAPT1) activity was unchanged. The parental tbat1(-/-) line was sensitive to lysis by melarsen oxide, and this process was inhibited by low concentrations of pentamidine, indicating the involvement of HAPT1. This pentamidine-inhibitable lysis was absent in the adapted line KO-B48. Likewise, uptake of the fluorescent diamidine 4', 6-diamidino-2-phenylindole dihydrochloride was much delayed in live KO-B48 cells and insensitive to competition with up to 10 mu M pentamidine. No overexpression of the Trypanosoma brucei brucei ATP-binding cassette transporter TbMRPA could be detected in KO-B48. We also show that a laboratory line of Trypanosoma brucei gambiense, adapted to high levels of resistance for the melaminophenyl arsenical drug melarsamine hydrochloride ( Cymelarsan), had similarly lost TbAT1 and HAPT1 activity while retaining LAPT1 activity. It seems therefore that selection for resistance to either pentamidine or arsenical drugs can result in a similar phenotype of reduced drug accumulation, explaining the occurrence of cross-resistance.