title: Stimulatory heterotrimeric GTP-binding protein inhibits hydrogen peroxide-induced apoptosis by repressing BAK induction in SH-SY5Y human neuroblastoma cells.
abstract: Heterotrimeric stimulatory GTP-binding protein (G(s)) stimulates adenylate cyclases to activate the cAMP signaling pathway. Although the cAMP pathway has been reported to be involved in apoptosis, the role of the G(s)-cAMP signaling pathway during reactive oxygen species (ROS)-mediated apoptosis, which is involved in the resistance of cancer cells to chemotherapy and radiation, is not clearly understood. Thus, in this study we aimed to investigate the role of the alpha subunit of G(s) (Galpha(s)) in the ROS-induced apoptosis of cancer cells. The stable expression of constitutively active Galpha(s) (Galpha(s)QL) inhibited the hydrogen peroxide-induced apoptosis of SH-SY5Y human neuroblastoma cells and reduced the hydrogen peroxide-induced increase in Bak and the decrease in Bcl-x(L) protein expression. Exogenous Bak expression abolished these inhibitory effects of Galpha(s)QL, but Bak small interfering RNA decreased hydrogen peroxide-induced apoptosis. Galpha(s) repressed hydrogen peroxide-induced Bak expression by inhibiting the transcription of Bak mRNA, which resulted from the inhibition of the hydrogen peroxide-induced activation of transcription factors such as AP1, NF-kappaB, and NFAT. Moreover, Galpha(s) also inhibited the hydrogen peroxide-induced binding of AP1, NF-kappaB, and NFAT to the Bak promoter. Furthermore, hydrogen peroxide-induced apoptosis was reduced by treating cells with prostaglandin E(2), which activates Galpha(s), but this was augmented by CCPA, which activates Galpha(i) causing a decrease in cAMP levels. From the results, we conclude that Galpha(s) protects neuroblastoma cells from hydrogen peroxide-induced apoptosis by repressing Bak induction, which is mediated by the inhibition of the hydrogen peroxide-induced activations of AP1, NF-kappaB, and NFAT through cAMP-PKA-CREB signaling system.
authors.affiliation: Department of Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799.
authors.forename: So-Young
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Department of Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799.
authors.forename: MiRan
authors.initials: M
authors.lastname: Seo
authors.affiliation: Department of Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799.
authors.forename: Yeni
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799.
authors.forename: Yun-Il
authors.initials: YI
authors.lastname: Lee
authors.affiliation: Department of Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799.
authors.forename: Jung-Min
authors.initials: JM
authors.lastname: Oh
authors.affiliation: Department of Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799.
authors.forename: Eun-Ah
authors.initials: EA
authors.lastname: Cho
authors.affiliation: Department of Microbiology, College of Medicine, Inha University, Incheon 402-751, Korea.
authors.forename: Jae-Seung
authors.initials: JS
authors.lastname: Kang
authors.affiliation: Department of Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799. Electronic address: juhnn@snu.ac.kr.
authors.forename: Yong-Sung
authors.initials: YS
authors.lastname: Juhnn
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008024:Ligands; D016328:NF-kappa B / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000235:genetics / Q000378:metabolism; D009447:Neuroblastoma / Q000201:enzymology / Q000473:pathology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D008024:Ligands; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D050998:bcl-2 Homologous Antagonist-Killer Protein; D006861:Hydrogen Peroxide; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D019205:GTP-Binding Protein alpha Subunits, Gs