p21Waf1/Cip1/Sdi1 induces permanent growth arrest with markers of replicative senescence in human tumor cells lacking functional p53

Oncogene. 1999 May 6;18(18):2789-97. doi: 10.1038/sj.onc.1202615.


We have shown previously that wild type p53 can rapidly induce replicative senescence in EJ human bladder carcinoma cells lacking functional p53. A major effector of p53 functions is p21Waf1/Cip1/Sdi1, a potent cyclin-dependent kinase inhibitor. p21Waf1/Cip1/Sdi1 has been shown to be involved in both p53 dependent and independent control of cell proliferation, differentiation and death. To directly investigate the effects of p21Waf1/Cip1/Sdi1 in the p53 response observed in EJ tumor cells, we established p21Waf1/Cip1/Sdi1 inducible lines using the tetracycline-regulatable vector system. p21Waf1/Cip1/Sdi1 induction caused irreversible cell cycle arrest in both G1 and G2/M, and diminished Cdk2 kinase activity. In addition, p21Waf1/Cip1/Sdi1 induction led to morphological alterations characteristic of cells undergoing replicative senescence with morphological, biochemical and ultrastructural markers of the senescent phenotype. Furthermore, sustained p21Waf1/Cip1/Sdi1 induction sensitized EJ cells to apoptotic cell death induced by mitomycin C, a cross-linking DNA damaging agent. These findings support the function of p21Waf1/Cip1/Sdi1 as an inducer of replicative senescence and a major mediator of this phenomenon in response to p53. Moreover, our results imply that therapeutic intervention in human cancers might be aimed at sustained elevation of p21Waf1/Cip1/Sdi1 expression.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / genetics
  • Biomarkers
  • CDC2-CDC28 Kinases*
  • Carcinoma / drug therapy
  • Carcinoma / genetics*
  • Carcinoma / pathology
  • Cell Division / genetics
  • Cellular Senescence / genetics*
  • Cross-Linking Reagents / pharmacology
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclin-Dependent Kinases / genetics
  • Cyclin-Dependent Kinases / metabolism
  • Cyclins / genetics*
  • Cyclins / metabolism
  • G1 Phase / genetics
  • G2 Phase / genetics
  • Gene Expression Regulation, Neoplastic
  • Genetic Engineering
  • Humans
  • Mitomycin / pharmacology
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism
  • Tetracycline / pharmacology
  • Tumor Cells, Cultured
  • Tumor Suppressor Protein p53 / genetics*
  • Urinary Bladder Neoplasms / drug therapy
  • Urinary Bladder Neoplasms / genetics*
  • Urinary Bladder Neoplasms / pathology
  • beta-Galactosidase / genetics
  • beta-Galactosidase / metabolism


  • Biomarkers
  • CDKN1A protein, human
  • Cross-Linking Reagents
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • Tumor Suppressor Protein p53
  • Mitomycin
  • Protein-Serine-Threonine Kinases
  • CDC2-CDC28 Kinases
  • CDK2 protein, human
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinases
  • beta-Galactosidase
  • Tetracycline