title: The choice between p53-induced senescence and quiescence is determined in part by the mTOR pathway.
abstract: Transient induction of p53 can cause reversible quiescence and irreversible senescence. Using nutlin-3a (a small molecule that activates p53 without causing DNA damage), we have previously identified cell lines in which nutlin-3a caused quiescence. Importantly, nutlin-3a caused quiescence by actively suppressing the senescence program (while still causing cell cycle arrest). Noteworthy, in these cells nutlin-3a inhibited the mTOR (mammalian Target of Rapamycin) pathway, which is known to be involved in the senescence program. Here we showed that shRNA-mediated knockdown of TSC2, a negative regulator of mTOR, partially converted quiescence into senescence in these nutlin-arrested cells. In accord, in melanoma cell lines and mouse embryo fibroblasts, which easily undergo senescence in response to p53 activation, nutlin-3a failed to inhibit mTOR. In these senescence-prone cells, the mTOR inhibitor rapamycin converted nutlin-3a-induced senescence into quiescence. We conclude that status of the mTOR pathway can determine, at least in part, the choice between senescence and quiescence in p53-arrested cells.
authors.affiliation: Department of Cell Stress Biology, Roswell Park Cancer Institute, BLSC, L3-312, Buffalo, NY 14263, USA.
authors.forename: Lioubov G
authors.initials: LG
authors.lastname: Korotchkina
authors.forename: Olga V
authors.initials: OV
authors.lastname: Leontieva
authors.forename: Elena I
authors.initials: EI
authors.lastname: Bukreeva
authors.forename: Zoya N
authors.initials: ZN
authors.lastname: Demidenko
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Gudkov
authors.forename: Mikhail V
authors.initials: MV
authors.lastname: Blagosklonny
mesh_terms: D000818:Animals; D016922:Cellular Senescence / Q000187:drug effects / Q000502:physiology*; D055785:Gene Knockdown Techniques; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D051379:Mice; D010879:Piperazines / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D058570:TOR Serine-Threonine Kinases; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D007093:Imidazoles; D047908:Intracellular Signaling Peptides and Proteins; D010879:Piperazines; D016159:Tumor Suppressor Protein p53; C482205:nutlin 3; C546842:MTOR protein, human; C546843:mTOR protein, mouse; D017346:Protein Serine-Threonine Kinases; D058570:TOR Serine-Threonine Kinases