title: Reactive oxygen species mediate doxorubicin induced p53-independent apoptosis.
abstract: Doxorubicin (DOX) is a common anticancer drug. The mechanisms of DOX induced apoptosis and the involvement of reactive oxygen species (ROS) in apoptotic signaling were investigated in p53-null human osteosarcoma Saos-2 cells. Accumulation of pre-G1 phase cells and induction of DNA laddering, which are the hallmarks of apoptosis, were detected in cells at 48 h upon DOX treatment. Furthermore, DOX increased the intracellular hydrogen peroxide and superoxide levels, followed by mitochondrial membrane depolarization, cytochrome c release, caspase-3 activation, prior to DNA laddering in Saos-2 cells. In addition, DOX treatment also upregulated Bax and downregulated Bcl-2 levels in the cells. The role of ROS in DOX induced cell death was confirmed by the suppression effect of catalase on DOX induced ROS formation, mitochondrial cytochrome c release, procaspase-3 cleavage, and apoptosis in Saos-2 cells. The catalase treatment however only suppressed DOX induced Bax upregulation but had no effect on Bcl-2 downregulation. Results from the present study suggested that ROS might act as the signal molecules for DOX induced cell death and the process is still functional even in the absence of p53.
authors.affiliation: Department of Biochemistry, The Chinese University of Hong Kong, Shatin, Hong Kong, PR China.
authors.forename: W P
authors.initials: WP
authors.lastname: Tsang
authors.forename: Sophia P Y
authors.initials: SP
authors.lastname: Chau
authors.forename: S K
authors.initials: SK
authors.lastname: Kong
authors.forename: K P
authors.initials: KP
authors.lastname: Fung
authors.forename: T T
authors.initials: TT
authors.lastname: Kwok
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002374:Catalase / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D003574:Cytochrome c Group / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology*; D004792:Enzyme Precursors / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology; D012516:Osteosarcoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D051028:bcl-2-Associated X Protein
chemical_list: D000970:Antineoplastic Agents; C494826:BAX protein, human; D003574:Cytochrome c Group; D004792:Enzyme Precursors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D004317:Doxorubicin; D002374:Catalase; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases