title: p53 mediates DNA damaging drug-induced apoptosis through a caspase-9-dependent pathway in SH-SY5Y neuroblastoma cells.
abstract: The signaling pathway for DNA damaging drug-triggered apoptosis was examined in a chemosensitive human neuroblastoma cell line, SH-SY5Y. Doxorubicin and etoposide induce rapid and extensive apoptosis in SH-SY5Y cells. After the drug treatment, p53 protein levels increase in the nucleus, leading to the induction of its transcription targets p21(Waf1/Cip1) and MDM2. Inactivation of p53, either by the human papillomavirus type 16 E6 protein or by a dominant-negative mutant p53 (R175H), completely protects SH-SY5Y cells from drug-triggered apoptosis. Cytochrome c and caspase-9 function downstream of p53 in mediating the drug-triggered apoptosis in SH-SY5Y cells. In drug-treated cells, cytochrome c is released, and caspase-9 becomes activated. Inactivation of p53 blocks cytochrome c release and caspase-9 activation. Furthermore, drug-induced cell death can be prevented by expression of a dominant-negative mutant of caspase-9. These findings define a molecular pathway for mediating DNA damaging drug-induced apoptosis in the human neuroblastoma SH-SY5Y cells and suggest that inactivation of essential components of this apoptotic pathway may confer drug resistance on neuroblastoma cells.
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical College of Ohio, Toledo, Ohio 43614, USA.
authors.forename: Hongjuan
authors.initials: H
authors.lastname: Cui
authors.forename: Allen
authors.initials: A
authors.lastname: Schroering
authors.forename: Han-Fei
authors.initials: HF
authors.lastname: Ding
mesh_terms: D017209:Apoptosis; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D004249:DNA Damage; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D004789:Enzyme Activation; D005047:Etoposide / Q000494:pharmacology; D016158:Genes, p53; D006801:Humans; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000201:enzymology; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology*; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D003574:Cytochrome c Group; D016159:Tumor Suppressor Protein p53; D005047:Etoposide; D004317:Doxorubicin; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases