Could the AXIN-based lysosomal pathway be involved in the anti-echinococcal effects of metformin?

LOOS JULIA .A.; DÁVILA VALERIA A.; COCCIMIGLIO MAGALÍ; CUMINO ANDREA C.

MAR DEL PLATA

Congreso; LXIII Reunión Anual de la Sociedad Argentina de Investigación Clínica; 2018

Sociedad Argentina de Investigaciones Clínicas

Echinococcosis is a neglected zoonotic disease caused by infection with the larval stage of tapeworms within the genus Echinococcus. Chemotherapy treatment for this disease has had limited effectiveness thus far, which is why it is a dire need to find new drugs for its treatment. We have previously shown that Metformin (Met), an anti-hyperglycemic and anti-proliferative drug, exhibits considerable in vitro and in vivo activity against E. granulosus larval stage (the causative agent of cystic echinococcosis). Here, we extended the study and evaluated the effect of the drug on E. multilocularis, the causative agent of alveolar echinococcosis (AE), a more aggressive variant of the disease. Metformin exerted a dose-dependent effect on the viability of totipotent parasite stem cells. By in toto immunolocalization assays, the expression and cellular localization of Em-AMPKα, Em-TOR, and Em-Atg8 were detected in the germinal layer of in vitro obtained metacestodes vesicles. The drug induced the activation of AMPK (Em-AMPKɑ-P176) as well as the reduction of the Ser3122-phosphorylated form of Em-TOR and the overexpression of the autophagic marker Em-Atg8. The induction of the autophagic process was concomitant with the nuclear localization of Em-foxO, which could be correlated with the transcriptional regulation of this pathway. Based on our in vitro results, we then examined the in vivo chemopreventive effect of Met on the growth of E. multilocularis larval stage in the murine AE infection model. Oral administration of Met (50 mg/kg/day) exhibited remarkable chemoprotective properties against secondary alveolar echinococcosis in mice. These results raise the question of whether Met controls the development of Echinococcus through the indirect inhibition of TOR, as a consequence of the ATP synthesis inhibition, and/or through the direct inhibition of TOR, by the Lysosomal pathway, which involve LAMPTOR and AXIN, identified in the parasite.