title: Autophagy contributes to therapy-induced degradation of the PML/RARA oncoprotein.
abstract: Treatment of acute promyelocytic leukemia (APL) with all-trans retinoic acid and/or arsenic trioxide represents a paradigm in targeted cancer therapy because these drugs cause clinical remission by affecting the stability of the fusion oncoprotein promyelocytic leukemia (PML)/retinoic acid receptor alpha (RARA). The authors of previous studies have implicated the ubiquitin-proteasome pathway as the main mechanism involved in therapy-induced PML/RARA degradation. Here we have investigated a role of autophagy, a protein degradation pathway that involves proteolysis of intracellular material within lysosomes. We found that both all-trans retinoic acid and arsenic trioxide induce autophagy via the mammalian target of rapamycin pathway in APL cells and that autophagic degradation contributes significantly both to the basal turnover as well as the therapy-induced proteolysis of PML/RARA. In addition, we observed a correlation between autophagy and therapy-induced differentiation of APL cells. Given the central role of the PML/RARA oncoprotein in APL pathogenesis, this study highlights an important role of autophagy in the development and treatment of this disease.
authors.affiliation: Department of Biochemistry, Institute of Basic Medical Sciences, University of Oslo, Blindern, Oslo, Norway.
authors.forename: Pauline
authors.initials: P
authors.lastname: Isakson
authors.forename: Magnar
authors.initials: M
authors.lastname: Bjørås
authors.forename: Stig Ove
authors.initials: SO
authors.lastname: Bøe
authors.forename: Anne
authors.initials: A
authors.lastname: Simonsen
mesh_terms: D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology; D001343:Autophagy / Q000187:drug effects* / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015514:Oncogene Proteins, Fusion / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010087:Oxides / Q000494:pharmacology; D000071156:Promyelocytic Leukemia Protein; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D018168:Receptors, Retinoic Acid / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000072482:Retinoic Acid Receptor alpha; D012995:Solubility; D058570:TOR Serine-Threonine Kinases; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001152:Arsenicals; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion; D010087:Oxides; D000071156:Promyelocytic Leukemia Protein; C000607071:RARA protein, human; D034741:RNA, Small Interfering; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C093476:promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein; C070576:PML protein, human; D014212:Tretinoin; C546842:MTOR protein, human; D017346:Protein Serine-Threonine Kinases; D058570:TOR Serine-Threonine Kinases; D000077237:Arsenic Trioxide