title: Bcl-2 activates a programme of premature senescence in human carcinoma cells.
abstract: The apoptosis regulator Bcl-2 has been shown to modulate cell-cycle progression, favouring a quiescent state over a proliferative state, in both normal and tumour cells. We show here that constitutive expression of Bcl-2 in human carcinoma cells results in a cell-cycle arrest that within a few days can become irreversible. Arrested cells acquire a senescent-like phenotype, which consists of several characteristic morphological alterations and increased activity of senescence-associated beta-galactosidase. The induction of the premature senescence programme is mediated by inhibition of Cdk2 kinase activity, and p27(KIP1) is required to maintain the senescent phenotype. We propose that the ability to activate an endogenous premature senescence programme allows Bcl-2 to suppress tumour growth. These results suggest that the down-regulation of Bcl-2 expression, which has been observed during the development and progression of human carcinoma, is related to the ability of Bcl-2 to severely hamper the growth of carcinoma cells and to induce a permanent cell-cycle arrest, with the features of senescence.
authors.affiliation: Molecular Haematology and Cancer Biology Unit, Institute of Child Health, University College of London, 30 Guilford Street, London WC1N 1EH, UK.
authors.forename: Elvira
authors.initials: E
authors.lastname: Crescenzi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Palumbo
authors.forename: Hugh J M
authors.initials: HJ
authors.lastname: Brady
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D042846:CDC2-CDC28 Kinases / Q000378:metabolism; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D016922:Cellular Senescence; D051357:Cyclin-Dependent Kinase 2; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004318:Doxycycline / Q000494:pharmacology; D006801:Humans; D010641:Phenotype; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D004318:Doxycycline