title: Inhibitory heterotrimeric GTP-binding proteins inhibit hydrogen peroxide-induced apoptosis by up-regulation of Bcl-2 via NF-kappaB in H1299 human lung cancer cells.
abstract: Inhibitory heterotrimeric GTP-binding proteins (Gi proteins) mediate a variety of signaling pathways by coupling receptors and effectors to regulate cellular proliferation, differentiation, and apoptosis. However, the role of Gi proteins in the modulation of hydrogen peroxide-induced apoptosis is not clearly understood. Thus, we investigated the effect of Gi proteins on hydrogen peroxide-induced apoptosis and the underlying mechanisms in H1299 human lung cancer cells. The stable expression of constitutively active alpha subunits of Gi1 (Galphai1QL), Gi2, or Gi3 inhibited hydrogen peroxide-induced apoptosis. The expression of Galphai1QL up-regulated Bcl-2 expression, and the knockdown of Bcl-2 with siRNA abolished the anti-apoptotic effect of Galphai1QL. Galphai1 induced the transcription of Bcl-2 by activation of NF-kappaB, which resulted from an increase in NF-kappaB p50 protein. We conclude that Galphai1 inhibits hydrogen peroxide-induced apoptosis of H1299 lung cancer cells by up-regulating the transcription of Bcl-2 through a p50-mediated NF-kappaB activation.
authors.affiliation: Department of Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, 28 Yongon-dong, Jongno-gu, Seoul 110-799, Republic of Korea.
authors.forename: Miran
authors.initials: M
authors.lastname: Seo
authors.forename: Hyo-Jung
authors.initials: HJ
authors.lastname: Nam
authors.forename: So-Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Yong-Sung
authors.initials: YS
authors.lastname: Juhnn
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008175:Lung Neoplasms / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D006861:Hydrogen Peroxide; D019206:GTP-Binding Protein alpha Subunits, Gi-Go