Laboratório de Bioquímica de Tripanosomatídeos, Instituto Oswaldo Cruz, IOC, Avenida Brasil 4365, Manguinhos, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.
Parasitol Res. 2013 Jun;112(6):2341-51. doi: 10.1007/s00436-013-3398-z. Epub 2013 Apr 10.
Drug resistance in protozoan parasites has been associated with the P-glycoprotein (Pgp), an energy-dependent efflux pump that transports substances across the membrane. Interestingly, the genes TcPGP1 and TcPGP2 have been described in Trypanosoma cruzi, although the function of these genes has not been fully elucidated. The main goal of this work was to investigate Pgp efflux pump activity and expression in T. cruzi lines submitted to in vitro induced resistance to the compounds 4-N-(2-methoxy styryl)-thiosemicarbazone (2-Meotio) and benznidazole (Bz) and to verify the stability of the resistant phenotypes during the parasite life cycle. We observed that the EC50 values for the treatment of epimastigotes with 2-Meotio or Bz were increased at least 4.7-fold in resistant lines, and this phenotype was maintained in metacyclic trypomastigotes, cell-derived trypomastigotes, and intracellular amastigotes. However, in epimastigotes, 2-Meotio resistance is reversible, but Bz resistance is irreversible. When compared with the parental line, the resistant lines exhibited higher Pgp efflux activity, reversion of the resistant phenotypes in the presence of Pgp inhibitors, cross-resistance with Pgp modulators, higher basal Pgp ATPase activity, and overexpression of the genes TcPGP1 and TcPGP2. In conclusion, the resistance induced in T. cruzi by the compounds 2-Meotio and Bz is maintained during the entire parasite life cycle. Furthermore, our data suggest the participation of the Pgp efflux pump in T. cruzi drug resistance.
寄生虫的抗药性与 P-糖蛋白(Pgp)有关,Pgp 是一种能量依赖性外排泵,可将物质运输穿过膜。有趣的是,在克氏锥虫中已经描述了基因 TcPGP1 和 TcPGP2,尽管这些基因的功能尚未完全阐明。这项工作的主要目的是研究 Pgp 外排泵活性和表达在 Trypanosoma cruzi 株中,这些株系已经对化合物 4-N-(2-甲氧基苯乙烯基)-硫代半卡巴腙(2-Meotio)和苯并硝唑(Bz)进行了体外诱导耐药,并验证耐药表型在寄生虫生命周期中的稳定性。我们观察到,在用 2-Meotio 或 Bz 处理epimastigotes 时,耐药株的 EC50 值至少增加了 4.7 倍,这种表型在 metacyclic trypomastigotes、细胞衍生的 trypomastigotes 和细胞内 amastigotes 中得以维持。然而,在 epimastigotes 中,2-Meotio 耐药是可逆的,但 Bz 耐药是不可逆的。与亲本株系相比,耐药株系表现出更高的 Pgp 外排活性,在 Pgp 抑制剂存在下耐药表型的逆转,与 Pgp 调节剂的交叉耐药性,更高的基础 Pgp ATP 酶活性,以及基因 TcPGP1 和 TcPGP2 的过度表达。总之,2-Meotio 和 Bz 在 T. cruzi 中诱导的耐药性在整个寄生虫生命周期中得以维持。此外,我们的数据表明 Pgp 外排泵参与了 T. cruzi 的药物耐药性。