Grogl M, Martin R K, Oduola A M, Milhous W K, Kyle D E
Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Washington, DC.
Am J Trop Med Hyg. 1991 Jul;45(1):98-111. doi: 10.4269/ajtmh.1991.45.98.
Multidrug-resistance (MDR) in neoplastic cells is frequently characterized by the overexpression of P-glycoprotein (PGP), a 170 kDa transmembrane glycoprotein that binds multiple cytotoxic drugs as well as calcium channel antagonists. Chloroquine resistance in Plasmodium falciparum appears to be analogous to MDR in neoplastic cells, where the induction of resistance with one drug confers resistance to other structurally and functionally unrelated drugs. To test the hypothesis that chloroquine resistance in P. falciparum and antimony resistance in Leishmania is mediated by a similar mechanism of MDR in mammalian neoplastic cells, a PGP-specific monoclonal antibody (C219) was used to determine the presence of PGP genes in resistant and sensitive Plasmodium and Leishmania parasites by indirect immunofluorescence assays and Western blotting procedures. These PGP-like components were detected in both drug-sensitive and -resistant Plasmodium and Leishmania cells. A 40-42 kDa component was observed to be greater in a chloroquine-resistant P. berghei (C line) than in a chloroquine-susceptible P line. Differences observed between Pentostam-resistant and -sensitive Leishmania promastigote clones and isolates included the increased expression of 96-106 and 23-25 kDa peptides in drug-resistant L. enrietti, and increased amounts of two different peptides in two drug-resistant L. panamensis clones (i.e., 96-106 and 43-45 kDa in WR-746-CL4, and 53 and 23-25 kDa in kDa) in amastigotes as in MDR KB carcinoma cells (KB-V1). Comparative indirect immunofluorescent studies suggested that a correlation existed between the degree of antimony susceptibility and the concentration of the moiety recognized by C219 in two L. panamensis clones. Binding of the C219 monoclonal antibody to the PGP-like component of Leishmania was blocked by Pentostam, while the binding of C219 to multiple-drug resistant KB-V1 PGP was not inhibited by Pentostam, regardless of the PGP concentration. This suggests some degree of specificity in the binding of Pentostam to the Leishmania PGP-like components. In addition, these studies have demonstrated that drug-sensitive Leishmania accumulate two to five times more 125Sb-Pentostam than resistant clones.
肿瘤细胞中的多药耐药性（MDR）通常表现为P-糖蛋白（PGP）的过度表达，PGP是一种170 kDa的跨膜糖蛋白，可结合多种细胞毒性药物以及钙通道拮抗剂。恶性疟原虫对氯喹的耐药性似乎类似于肿瘤细胞中的MDR，即一种药物诱导的耐药性会使细胞对其他结构和功能无关的药物产生耐药性。为了验证恶性疟原虫对氯喹的耐药性和利什曼原虫对锑的耐药性是由与哺乳动物肿瘤细胞中类似的MDR机制介导的这一假说，使用了一种PGP特异性单克隆抗体（C219），通过间接免疫荧光测定和蛋白质印迹法来确定耐药和敏感的疟原虫及利什曼原虫中PGP基因的存在情况。在对药物敏感和耐药的疟原虫及利什曼原虫细胞中均检测到了这些类似PGP的成分。观察到在氯喹耐药的伯氏疟原虫（C系）中，一种40 - 42 kDa的成分比氯喹敏感的P系中更多。在喷他脒耐药和敏感的利什曼原虫前鞭毛体克隆及分离株之间观察到的差异包括，在耐药的恩氏利什曼原虫中96 - 106 kDa和23 - 25 kDa肽段的表达增加，以及在两个耐药的巴拿马利什曼原虫克隆（即WR - 746 - CL4中的96 - 106 kDa和43 - 45 kDa，以及kDa中的53 kDa和23 - 25 kDa）的无鞭毛体中，与多药耐药的KB癌细胞（KB - V1）一样，两种不同肽段的含量增加。比较间接免疫荧光研究表明，在两个巴拿马利什曼原虫克隆中，锑敏感性程度与C219识别的部分的浓度之间存在相关性。喷他脒可阻断C219单克隆抗体与利什曼原虫类似PGP成分的结合，而无论PGP浓度如何，喷他脒均不抑制C219与多药耐药的KB - V1 PGP的结合。这表明喷他脒与利什曼原虫类似PGP成分的结合具有一定程度的特异性。此外，这些研究表明，药物敏感型利什曼原虫积累的125Sb - 喷他脒比耐药克隆多两到五倍。
