title: UCP2 inhibition triggers ROS-dependent nuclear translocation of GAPDH and autophagic cell death in pancreatic adenocarcinoma cells.
abstract: Mitochondrial uncoupling protein 2 (UCP2) can moderate oxidative stress by favoring the influx of protons into the mitochondrial matrix, thus reducing electron leakage from respiratory chain and mitochondrial superoxide production. Here, we demonstrate that UCP2 inhibition by genipin or UCP2 siRNA strongly increases reactive oxygen species (ROS) production inhibiting pancreatic adenocarcinoma cell growth. We also show that UCP2 inhibition triggers ROS-dependent nuclear translocation of the glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH), formation of autophagosomes, and the expression of the autophagy marker LC3-II. Consistently, UCP2 over-expression significantly reduces basal autophagy confirming the anti-autophagic role of UCP2. Furthermore, we demonstrate that autophagy induced by UCP2 inhibition determines a ROS-dependent cell death, as indicated by the apoptosis decrease in the presence of the autophagy inhibitors chloroquine (CQ) or 3-methyladenine (3-MA), or the radical scavenger NAC. Intriguingly, the autophagy induced by genipin is able to potentiate the autophagic cell death triggered by gemcitabine, the standard chemotherapeutic drug for pancreatic adenocarcinoma, supporting the development of an anti-cancer therapy based on UCP2 inhibition associated to standard chemotherapy. Our results demonstrate for the first time that UCP2 plays a role in autophagy regulation bringing new insights into mitochondrial uncoupling protein field.
authors.affiliation: Department of Life and Reproduction Sciences, Biochemistry Section, University of Verona, Verona, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Dando
authors.forename: Claudia
authors.initials: C
authors.lastname: Fiorini
authors.forename: Elisa Dalla
authors.initials: ED
authors.lastname: Pozza
authors.forename: Chiara
authors.initials: C
authors.lastname: Padroni
authors.forename: Chiara
authors.initials: C
authors.lastname: Costanzo
authors.forename: Marta
authors.initials: M
authors.lastname: Palmieri
authors.forename: Massimo
authors.initials: M
authors.lastname: Donadelli
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002756:Cholagogues and Choleretics / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D039823:Iridoids / Q000494:pharmacology*; D024101:Mitochondrial Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000071246:Uncoupling Protein 2
chemical_list: D002756:Cholagogues and Choleretics; D007473:Ion Channels; D039823:Iridoids; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C000604389:UCP2 protein, human; D000071246:Uncoupling Protein 2; C007834:genipin; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases