Inhibitors of cyclin-dependent kinases induce features of replicative senescence in early passage human diploid fibroblasts

Curr Biol. 1998 Mar 12;8(6):351-4. doi: 10.1016/s0960-9822(98)70137-x.


After a limited number of population doublings (PDs), cultures of normal mammalian diploid cells undergo an irreversible growth arrest known as replicative senescence [1]. As well as contributing to cellular ageing, senescence is viewed as an important mechanism of tumour suppression by preventing the emergence of immortal cell clones [2-4]. Senescent cells have a number of characteristics that distinguish them from cycling or quiescent cells including elevated levels of two cyclin-dependent kinase (Cdk) inhibitors, p16INK4a and p21CIP1 [5-11]. Here, we demonstrate that both of these Cdk inhibitors, as well as other members of their protein families (the INK4 and CIP/KIP families, respectively [12]), induce several facets of the senescent phenotype when ectopically expressed in young human diploid fibroblasts. These include a reduced proliferative capacity, an altered size and shape, the presence of underphosphorylated retinoblastoma protein (pRb), increased expression of plasminogen activator inhibitor (PAI-1) and the appearance of senescence-associated beta-galactosidase (SA-beta-gal) activity [2,3,13-15]. A 20 amino acid peptide from p16INK4a that inhibits Cdks active in the G1 phase of the cell cycle [16] produces similar effects in a dose-dependent manner suggesting that, in primary fibroblasts, inhibition of G1-specific Cdk activity is sufficient to induce phenotypic changes that normally occur at the end of their finite lifespan.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Cycle Proteins*
  • Cells, Cultured
  • Cellular Senescence / physiology
  • Cyclin-Dependent Kinase Inhibitor p15
  • Cyclin-Dependent Kinase Inhibitor p16 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclin-Dependent Kinase Inhibitor p27
  • Cyclin-Dependent Kinases / antagonists & inhibitors*
  • Cyclins / metabolism
  • Enzyme Inhibitors / administration & dosage
  • Fibroblasts / physiology*
  • Fluorescent Antibody Technique
  • Humans
  • Microtubule-Associated Proteins / metabolism
  • Phenotype
  • RNA
  • Time Factors
  • Transcription Factors / metabolism
  • Tumor Suppressor Proteins*


  • CDKN1A protein, human
  • CDKN2B protein, human
  • Cell Cycle Proteins
  • Cyclin-Dependent Kinase Inhibitor p15
  • Cyclin-Dependent Kinase Inhibitor p16
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • Enzyme Inhibitors
  • Microtubule-Associated Proteins
  • Transcription Factors
  • Tumor Suppressor Proteins
  • Cyclin-Dependent Kinase Inhibitor p27
  • RNA
  • Cyclin-Dependent Kinases