title: Cationic liposomes induce apoptosis through p38 MAP kinase-caspase-8-Bid pathway in macrophage-like RAW264.7 cells.
abstract: We have demonstrated that cationic liposomes composed of stearylamine (SA-liposomes) induce apoptosis in a variety of cells, but the mechanism responsible for the cellular death is not clear. In this paper, we investigated the signaling pathways implicated in SA-liposome-induced apoptosis in the macrophage-like cell line RAW264.7. Treatment with SA-liposomes caused the activation of mitogen-activated protein kinases (MAPKs), especially p38 and c-jun N-terminal kinase, and apoptosis was only inhibited upon the addition of a specific inhibitor for p38. N-acetylcysteine, a scavenger of reactive oxygen species (ROS), effectively inhibited the activation of p38 and cellular death, indicating that the activation induced by ROS is an initial step in the process of apoptosis triggered by SA-liposomes. Caspase-8 was activated by p38, and caspase-8-dependent cleavage of Bid was also observed. No down-regulation of bcl-2 expression, and no cleavage of Bax protein were observed. Taken together, our results suggest that apoptosis of RAW264.7 by SA-liposomes was mediated by the MAPK p38 and a caspase-8-dependent Bid-cleavage pathway. Moreover, we found that ROS can contribute intimately to the SA-liposome-induced cell death in RAW264.7.
authors.affiliation: School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Iwaoka
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nakamura
authors.forename: Shuhei
authors.initials: S
authors.lastname: Takano
authors.forename: Seishi
authors.initials: S
authors.lastname: Tsuchiya
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Aramaki
mesh_terms: D000588:Amines / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D015536:Down-Regulation / Q000187:drug effects; D016166:Free Radical Scavengers / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008081:Liposomes / Q000737:chemistry / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D051379:Mice; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012694:Serine / Q000031:analogs & derivatives / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000588:Amines; D051023:BH3 Interacting Domain Death Agonist Protein; C494815:Bid protein, mouse; D016166:Free Radical Scavengers; D008081:Liposomes; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; C115688:sterylamine; D012694:Serine; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C505526:Casp8 protein, mouse; D053181:Caspase 8; D020169:Caspases; C012162:N-acetylserine