IHEM   20887
INSTITUTO DE HISTOLOGIA Y EMBRIOLOGIA DE MENDOZA DR. MARIO H. BURGOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
CHANGES IN DISTRIBUTION OF CATHEPSIN D AND CATION-DEPENDENT MANNOSE-6-PHOSPHATE RECEPTOR INDUCED BY CHLOROQUINE IN BREAST CANCER CELLS
Autor/es:
PERALTA S; CARVELLI L; VARGAS-ROIG L; PEREIRA LAURA; SOSA MIGUEL ANGEL
Reunión:
Congreso; XXXVI Reunión Anual de la Sociedad de Biología de Cuyo; 2020
Resumen:
Breast cancer causes high mortality worldwide. The cells of some tumors have increased lysosomal biogenesis as response to its altered metabolism. These events affect lysosomal integrity and/or functionality, where increased levels of lysosomal proteases such as cathepsin D (CatD) are observed. In most cell types, lysosomal proteins are selectively transported from the trans Golgi network (TGN) to lysosomes by the mannose-6-phosphate receptors (CD-MPR and CI-MPR). In acidic compartments (e.g. late endosomes) the complexes enzyme-MPR are dissociated and receptors recycled back. Alterations in the lysosomal membrane lead to a CatD drainage into the cytoplasm, triggering apoptotic processes. Thus lysosomes appear as potential therapeutic targets for antitumor drugs. Acidotropic amines usually accumulate in lysosomes and could induce an increase in lysosomal membrane permeability, leading to an escape of enzymes into the cytoplasm. Chloroquine (CQ)is an acidotropic amine known to affect lysosomal acidification and inhibits autophagy. The aim of this study was to evaluate the effect of CQ on the distribution of CatD and CD-MPR in human mammary tumor cells MCF-7. Cultures incubated with CQ at different times and processed for detection of CatD and CD-MPR by indirect immunofluorescence. After 6 h incubation with CQ, CD-MPR is mostly distributed in the cytoplasm indicating that increasing of lysosomal pH prevents the recycling of CD-MPR to Golgi.In turn, the TGN becomes disorganized and its markers co-localize with the CD-MPR. However, CatD exhibits an apparent increase in perinuclear labeling compared to control cells. This could be explained by a delay in the transport of the newly synthesized enzymes to the lysosomes Surprisingly, at 12 h of incubation the perinuclear CatD signal is redistributed throughout the cytoplasm, indicating that it would have reached the lysosomes. At 18 h, CD-MPR and CatD fully recovered their initial location, denoting that the effect of CQ is lost over time.. From these preliminary results we conclude that CQ affect the lysosomal system , altering the normal transport and processing of CatD, although the effect is not lasting. The mechanism by which the effect of CQ is reversed should be elucidated.