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

NICOLAO MA. CELESTE; LOOS JULIA A.; RODRIGUEZ RODRIGUES C; BEAS VIVIANA; CUMINO ANDREA CARINA

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2017 vol. 12

1932-6203

Cystic echinococcosis (CE) is a worldwide distributed helminthic zoonosis caused byEchinococcus granulosus. Benzimidazole derivatives are currently the only drugs forchemotherapeutic treatment of CE. However, their low efficacy and the adverse effectsencourage the search for new therapeutic targets. We evaluated 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 and 0.5 μM inprotoscoleces and metacestodes, respectively (P < 0.05). After 48 h of exposure to thisdrug, it was triggered a mRNA overexpression of chaperones (Eg-grp78 and Egcalnexin)and of Eg-ire2/Eg-xbp1 (the conserved UPR pathway branch) inprotoscoleces. No changes were detected in the transcriptional expression ofchaperones in Bz-treated metacestodes, thus allowing ER stress to be evident andviability to highly decrease in comparison with protoscoleces. We also found that Bztreatment activated the autophagic process in both larval forms. These facts wereevidenced by the increase in the amount of transcripts of the autophagy related genes(Eg-atg6, Eg-atg8, Eg-atg12, Eg-atg16) together with the increase in Eg-Atg8-IIdetected by western blot and by in toto immunofluorescence labeling. It was furtherconfirmed by direct observation of autophagic structures by electronic microscopy.Finally, in order to determine the impact of autophagy induction on Echinococcus cellviability, we evaluated the efficacy of Bz in combination with rapamycin and asynergistic cytotoxic effect on protoscolex viability was observed when both drugs wereused together. In conclusion, our findings demonstrated that Bz induced endoplasmicreticulum stress, autophagy and subsequent death allowing to identify unstudiedparasite-host pathways that could provide a new insight for control of parasiticdiseases.