title: PI3K inhibitors changed the p53-induced response of Saos-2 cells from growth arrest to apoptosis.
abstract: p53 is activated by stress leading to oncogenic alteration, which induces either cell cycle arrest or apoptosis, although the mechanism involved in this decision has not been fully clarified as yet. This work was undertaken to change the cellular response by inducing apoptosis with PI3K inhibitors to Saos-2 cells that had been growth-arrested in both G1 and G2/M by the wild-type activity of temperature-sensitive (ts) p53. We found that the PI3K/Akt inhibitors LY294002 and wortmannin, but not the MEK inhibitor U0126, were capable of inducing apoptosis in growth-arrested Saos-2 cells, as assessed by an increase in the sub-G1 population, pyknotic nuclei, and DNA ladder formation. We detected the cleavage of caspases 9 and 3, and PARP after LY294002 addition, accompanied by a loss of cytochrome c from the mitochondria, and observed Bax translocation to the mitochondria and down-regulation of phospho-Akt, suggesting that blocking of survival signals triggered the apoptotic signal through the mitochondrial apoptotic pathway. It is thus suggested that the PI3K/Akt pathway played an important role in determining cell fate between growth arrest and apoptosis.
authors.affiliation: Department of Molecular Cellular Oncology and Microbiology, Graduate School of Medicine and Dentistry, Tokyo Medical Dental University, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Shuo
authors.initials: S
authors.lastname: Ren
authors.forename: ChongFeng
authors.initials: C
authors.lastname: Gao
authors.forename: Lilin
authors.initials: L
authors.lastname: Zhang
authors.forename: Katsuro
authors.initials: K
authors.lastname: Koike
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tsuchida
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002070:Butadienes / Q000494:pharmacology; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects* / Q000502:physiology; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D006868:Hydrolysis; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*; D000077191:Wortmannin; D051028:bcl-2-Associated X Protein
chemical_list: D000730:Androstadienes; C494826:BAX protein, human; D002070:Butadienes; D002867:Chromones; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D009025:Morpholines; D009570:Nitriles; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; C113580:U 0126; D051028:bcl-2-Associated X Protein; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; D000077191:Wortmannin