Engineered mutants of pRB with improved growth suppression potential

Oncogene. 1997 Dec 4;15(23):2855-66. doi: 10.1038/sj.onc.1201465.


We have constructed a panel of substitution mutants which affect one or more of the putative cdk target sites of the RB protein. We have examined the activity of these mutants relative to wild-type RB by both a transcriptional repression assay and by measuring growth suppression in vitro. We find that some phosphorylation site mutants of pRB can repress E2 transcription more strongly than wild-type RB. These mutants are partially resistant to phosphorylation by cdks and can arrest tumor cells in G1 in vitro. Our results indicate a functional correlation between the ability to repress E2F-dependent transcription and the ability to suppress tumor cell growth in vitro. In addition, we describe two classes of RB mutants: N-terminal truncated p56RB and a novel mutant of RB containing multiple substitutions near its nuclear localization signal. Both classes of RB mutants have greater activity than the wild-type protein. Because RB is a key regulator of cell cycle progression, expression of a more potent, phosphorylation resistant RB may have utility in both RB(-/-) and RB(+/+) tumors as well as in hyperproliferative disorders.

MeSH terms

  • Amino Acid Substitution / genetics*
  • Antineoplastic Agents / antagonists & inhibitors
  • Antineoplastic Agents / metabolism
  • Binding Sites / genetics
  • Carrier Proteins*
  • Cell Cycle Proteins*
  • Cyclin E / physiology
  • Cyclin-Dependent Kinases / physiology
  • DNA-Binding Proteins*
  • E2F Transcription Factors
  • G1 Phase / drug effects
  • G1 Phase / genetics
  • Growth Inhibitors / antagonists & inhibitors
  • Growth Inhibitors / genetics*
  • Growth Inhibitors / metabolism
  • Growth Inhibitors / physiology*
  • Humans
  • Mutagenesis, Site-Directed*
  • Osteosarcoma
  • Phosphorylation
  • Retinoblastoma Protein / antagonists & inhibitors
  • Retinoblastoma Protein / genetics*
  • Retinoblastoma Protein / metabolism
  • Retinoblastoma Protein / physiology*
  • Retinoblastoma-Binding Protein 1
  • Sequence Deletion
  • Transcription Factor DP1
  • Transcription Factors / physiology
  • Tumor Cells, Cultured


  • Antineoplastic Agents
  • Carrier Proteins
  • Cell Cycle Proteins
  • Cyclin E
  • DNA-Binding Proteins
  • E2F Transcription Factors
  • Growth Inhibitors
  • Retinoblastoma Protein
  • Retinoblastoma-Binding Protein 1
  • Transcription Factor DP1
  • Transcription Factors
  • Cyclin-Dependent Kinases