P-glycoprotein efflux pump plays an important role in Trypanosoma cruzi drug resistance

Abstract

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.

Thiol efflux mediated by an ABCC-like transporter participates forTrypanosoma cruziadaptation to environmental and chemotherapeutic stresses

“…Parasites were submitted to the same procedure up to 8 weeks. Then, the concentration of benznidazole was increased in 10 µM per week up to a final concentration of 120 µM (74). Resistance to benznidazole was then evaluated by the MTT reduction assay as described before.…”

Current and Future Prospects of Nitro-compounds as Drugs for Trypanosomiasis and Leishmaniasis

“…However, one study reported contradictory findings suggesting upregulation of Old Yellow Enzyme rather than downregulation and found no changes in enzyme levels of cytochrome P450 reductase [130] or superoxide dismutase [130]. P-glycoprotein efflux pumps have also been implicated in drug resistance by some investigators [139] but not others [140]. Clearly further investigations are required to clarify some of these conflicting findings.…”

Clinical and pharmacological profile of benznidazole for treatment of Chagas disease

“…Several in vitro and in vivo studies suggest, via a comparison of parasite growth kinetics and cure rates in animal models, evaluation of shifts in IC 50 values, and molecular approaches, that there is the potential for development of resistance to BZN [36,[59][60][61][62]. However, while there is clear evidence of resistance in T. cruzi under multiple experimental conditions, a direct link between in vitro/in vivo susceptibility and the clinical efficacy of BZN is still undefined.…”

“…The mechanism of generation of resistance is likely to be multifactorial, involving higher activity of efflux pumps, and mutation and/or modulation of parasite gene expression [34,36,[59][60][61][62]. A recent whole genome sequencing study showed that mutagenic effects of BZN-reactive metabolites, combined with deficiencies in DNA repair mechanisms, could generate early-stage, extensive alterations in the T. cruzi genome, leading to the development of BZN resistance and other phenotypic changes [63].…”