title: Azacitidine-resistant SKM1 myeloid cells are defective for AZA-induced mitochondrial apoptosis and autophagy.
abstract: Azacitidine (AZA) is the current treatment for patients with high-risk myelodysplastic syndrome, but resistance is a common feature of AZA-treated patients. To investigate the mechanisms associated with AZA resistance in vitro, we generated AZA-resistant SKM1 myeloid cells, called hereafter AZA-R. AZA-R cells exhibit impaired mitochondrial membrane permeabilization and caspase activation in response to AZA compared to their AZA-sensitive (AZA-S) counterpart. AZA induced LC3-II accumulation and cathepsin B activity in AZA-S cells, two hallmarks of autophagy. AZA-R cells displayed increased basal autophagy but are resistant to AZA-mediated autophagy. Inhibition of autophagy using LC3 siRNA revealed that autophagy is protective in AZA-S cells and AZA-R cells in basal conditions. By contrast, AZA-R cells exhibited impaired autophagy in response to AZA. Collectively, our findings indicate that AZA promotes apoptosis and autophagy in SKM1 cells, and that AZA-R cells are resistant to both apoptosis and autophagy induced by AZA.
authors.affiliation: Cell Death, Differentiation, Inflammation and Cancer Team, Inserm U895, Nice, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Cluzeau
authors.forename: Guillaume
authors.initials: G
authors.lastname: Robert
authors.forename: Alexandre
authors.initials: A
authors.lastname: Puissant
authors.forename: Karsenti
authors.initials: K
authors.lastname: Jean-Michel
authors.forename: Jill-Patrice
authors.initials: JP
authors.lastname: Cassuto
authors.forename: Sophie
authors.initials: S
authors.lastname: Raynaud
authors.forename: Patrick
authors.initials: P
authors.lastname: Auberger
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis; D001343:Autophagy; D001374:Azacitidine / Q000494:pharmacology*; D045744:Cell Line, Tumor; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects*; D009190:Myelodysplastic Syndromes / Q000473:pathology; D034622:RNA Interference; D034741:RNA, Small Interfering
chemical_list: D000964:Antimetabolites, Antineoplastic; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; D001374:Azacitidine