Accumulation of high levels of the p53 and p130 growth-suppressing proteins in cell lines stably over-expressing cyclin-dependent kinase 6 (cdk6)

Oncogene. 2001 May 24;20(23):2889-99. doi: 10.1038/sj.onc.1204396.


Cyclin-dependent kinase 6(cdk6) is present in randomly proliferating cultures of 3T3 cells but has little detectable enzymatic activity. Significant activity is detected only during a short period in early G1 phase. To examine the possible functions of cdk6 in 3T3 cells, lines stably over-expressing cdk6 were constructed and compared to normal 3T3 cells or cell lines with reduced cdk6 levels due to expression of a dominant-negative form of the protein. Over-expression of cdk6 in cells, which led to high levels of activity even in proliferating cultures, had dramatic effects. Cell lines stably over-expressing wild-type cdk6 had a markedly reduced growth rate compared to parental 3T3 cells or lines expressing a dominant-negative form of cdk6. They also over-produced the p53 and p130 proteins and had increased sensitivity to UV-irradiation. Irradiation resulted in accumulation of the Bax protein and rapid cell death. Levels of p53 and p130 proteins were down-regulated and the growth rate of the cells was increased by introduction of the dominant-negative form of cdk6 into cells over-expressing cdk6, indicating that cdk6 is involved in the overproduction of p53 and p130. The results suggest that cdk6, through regulation of growth-suppressing molecules, may play a role in halting cellular growth when proliferation is inappropriate.

Publication types

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

MeSH terms

  • 3T3 Cells / radiation effects
  • Animals
  • Cell Division / genetics
  • Cell Line / radiation effects
  • Culture Media, Serum-Free
  • Cyclin-Dependent Kinase 6
  • Cyclin-Dependent Kinases*
  • Mice
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins / radiation effects
  • Proto-Oncogene Proteins c-bcl-2*
  • Transfection
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • bcl-2-Associated X Protein


  • Bax protein, mouse
  • Culture Media, Serum-Free
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Tumor Suppressor Protein p53
  • bcl-2-Associated X Protein
  • Protein-Serine-Threonine Kinases
  • Cdk6 protein, mouse
  • Cyclin-Dependent Kinase 6
  • Cyclin-Dependent Kinases