Metformina inhibe la viabilidad de Echinococcus granulosus mediante aumento de autofagia.

LOOS, JULIA A.; CUMINO ANDREA C.

Buenos Aires

Congreso; XXV Reunión Anual de la Sociedad Argentina de Protozoología y Enfermedades Parasitarias; 2012

Sociedad Argentina de Protozoología

Interruption of TOR-dependent signaling by rapamycin is known to stimulate autophagy, in mammalian and yeast cells. As the activation of AMPK also inhibits directly TOR-dependent signaling, through phosphorylation of raptor, stimulation of autophagy by AMPK activation is expected. This is true for yeast and mammalian cells, but it is unknown in the cestode parasite Echinococcus granulosus (Eg), causative agent of the human hydatid disease. Hypoglucemiant drug metformin, recently proposed as an anticancer agent, is a way to stimulate AMPK activity. To examine the possible role of AMPK in the control of autophagy in E. granulosus, we studied the effects of metformin on the viability of protoscoleces and cysts. The drug reduced the vitality of protoscoleces in a dose-dependent manner and induced the deleterious effect on germinal layer of cysts determined by SEM. Metformin also increased the level of acidic vesicles (detected by staining with acridine orange and confocal microscopy), determined the presence of autophagosomes (detected by TEM) and upregulated the LC3II expression (confirmed by immunoblot) in treated protoscoleces. Furthermore, we studied the expression of regulatory and structural genes involved in the formation of autolysosomes described in Eg, such as atg6, atg8, atg9, atg12, atg16 and atg18. Previous works in our laboratory reported the existence of TOR in addition to induction of autophagy by rapamycin in Eg. On this basis, we identified one Eg-raptor ortholog (in the contig pathogen_EgG_scaffold_0006, which ORF contains 1147 amino acis and characteristic domains), that showed 42% and 37% of identity and 57% and 52% of homology with Homo sapiens (BAH12314) and Ascaris suum (ADY40316) orthologs, respectively. These results reveal that the induction of autophagy by metformin could be related to its ability to activate AMPK. Also, the sensitivity of these two drugs plus bioinformatic results may be suggesting the presence of the TORC1 complex in Eg.