The benzoquinone ansamycin geldanamycin stimulates proteolytic degradation of focal adhesion kinase

Mol Genet Metab. 1999 Jan;66(1):24-30. doi: 10.1006/mgme.1998.2774.


FAK is a nonreceptor tyrosine kinase involved in adhesion-mediated signal transduction whose level of expression is related to the invasiveness of malignant tumors. In seeking strategies to downregulate FAK, we treated various cell lines in vitro with the benzoquinone ansamycin geldanamycin (GA) which was previously described as a tyrosine kinase inhibitor, but recently has been shown to exert its effects by interfering with the chaperone function of members of the hsp90 family of heat-shock proteins. We evaluated the effects of benzoquinone ansamycins on FAK steady-state protein level and FAK half-life in breast and prostate carcinoma, Ewing's sarcoma, and 3T3 fibroblasts. Our data demonstrate that GA stimulates the proteolytic degradation of FAK in all cell lines examined and markedly reduces the half-life of newly synthesized FAK protein without significantly altering the level of FAK mRNA. These data demonstrate FAK to be another tyrosine kinase sensitive to the destabilizing effects of benzoquinone ansamycins and further show that small molecule-mediated pharmacologic modulation of FAK protein level is a feasible approach to the interdiction of FAK function.

MeSH terms

  • 3T3 Cells
  • Animals
  • Benzoquinones / pharmacology
  • Cell Adhesion Molecules / chemistry*
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism
  • Cysteine Endopeptidases / metabolism
  • Enzyme Inhibitors / pharmacology*
  • Enzyme Stability / drug effects
  • Focal Adhesion Kinase 1
  • Focal Adhesion Protein-Tyrosine Kinases
  • Hydrolysis / drug effects
  • Lactams, Macrocyclic
  • Mice
  • Multienzyme Complexes / metabolism
  • Proteasome Endopeptidase Complex
  • Protein-Tyrosine Kinases / chemistry*
  • Protein-Tyrosine Kinases / genetics
  • Protein-Tyrosine Kinases / metabolism
  • Quinones / pharmacology*
  • RNA, Messenger / drug effects
  • RNA, Messenger / genetics
  • Rifabutin / pharmacology
  • Tumor Cells, Cultured


  • Benzoquinones
  • Cell Adhesion Molecules
  • Enzyme Inhibitors
  • Lactams, Macrocyclic
  • Multienzyme Complexes
  • Quinones
  • RNA, Messenger
  • Rifabutin
  • quinone
  • Protein-Tyrosine Kinases
  • Focal Adhesion Kinase 1
  • Focal Adhesion Protein-Tyrosine Kinases
  • Ptk2 protein, mouse
  • Cysteine Endopeptidases
  • Proteasome Endopeptidase Complex
  • geldanamycin