Bortezomib initiates endoplasmic reticulum stress, elicits autophagy and death in Echinococcus granulosus larval stage

MARÍA CELESTE NICOLAO; JULIA A. LOOS; CHRISTIAN RODRIGUEZ RODRIGUES; VIVIANA BEAS; ANDREA C. CUMINO

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2017

1932-6203

Cystic echinococcosis (CE) is a worldwidedistributed helminthic zoonosis caused by Echinococcusgranulosus. Benzimidazolederivatives are currently the only drugs for chemotherapeutic treatment of CE.However, their low efficacy and the adverse effects encourage the search for newtherapeutic targets. Weevaluated the in vitro efficacy ofBortezomib (Bz), a proteasome inhibitor, in the larval stage of the parasite.After 96 h, Bz showed potent deleterious effects at a concentration of 5 μM and0.5 μM in protoscoleces and metacestodes, respectively (P < 0.05). After 48h of exposure to this drug, it was triggered a mRNA overexpression ofchaperones (Eg-grp78 and Eg-calnexin)and of Eg-ire2/Eg-xbp1 (the conserved UPR pathway branch)in protoscoleces. Nochanges were detected in the transcriptional expression of chaperones inBz-treated metacestodes, thus allowing ER stress to be evident and viability tohighly decrease in comparison with protoscoleces. We also found that Bz treatment activated theautophagic process in both larval forms. These facts were evidenced by the increase inthe amount of transcripts of the autophagy related genes (Eg-atg6, Eg-atg8, Eg-atg12, Eg-atg16) together with the increase inEg-Atg8-II detected by western blot and by intoto immunofluorescence labeling. It was further confirmed by directobservation of autophagic structures by electronic microscopy. Finally, inorder to determine the impact of autophagy induction on Echinococcus cell viability, we evaluated the efficacy of Bz incombination with rapamycinand a synergistic cytotoxic effect on protoscolex viability was observedwhen both drugs were used together. In conclusion, our findings demonstratedthat Bz induced endoplasmic reticulum stress, autophagy and subsequent deathallowing to identify unstudied parasite-host pathways that could provide a newinsight for control of parasitic diseases.