Dislodgment and accelerated degradation of Ras

Biochemistry. 1998 Feb 3;37(5):1306-14. doi: 10.1021/bi972032d.


Membrane anchorage of Ras oncoproteins, required for transforming activity, depends on their carboxy-terminal farnesylcysteine. We previously showed that S-trans,trans-farnesylthiosalicylic acid (FTS), a synthetic farnesylcysteine mimetic, inhibits growth of ErbB2- and Ras-transformed cells, but not of v-Raf-transformed cells, suggesting that FTS interferes specifically with Ras functions. Here we demonstrate that FTS dislodges Ras from membranes of H-Ras-transformed (EJ) cells, facilitating its degradation and decreasing total cellular Ras. The dislodged Ras that was transiently present in the cytosol was degraded relatively rapidly, causing a decrease of up to 80% in total cellular Ras. The half-life of Ras was 10 +/- 4 h in FTS-treated EJ cells and 27 +/- 4 h in controls. The dislodgment of membrane Ras and decrease in total cellular Ras were dose-dependent: 50% of the effects occurred at 10-15 microM, comparable to concentrations (7-10 microM) required for 50% growth inhibition in EJ cells. Higher concentrations of FTS (25-50 microM) were required to dislodge Ras from Rat-1 cell membranes expressing normal Ras, suggesting some selectivity of FTS toward oncogenic Ras. Membrane localization of the prenylated G beta gamma of heterotrimeric G proteins was not affected by FTS in EJ cells. An FTS-related compound, N-acetyl-S-farnesyl-L-cysteine, which does not inhibit EJ cell growth, did not affect Ras. FTS did not inhibit growth of Rat-1 cells transformed by N-myristylated H-Ras and did not reduce the total amount of this Ras isoform. The results suggest that FTS affects docking of Ras in the cell membrane in a rather specific manner, rendering the protein susceptible to proteolytic degradation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcysteine / analogs & derivatives
  • Acetylcysteine / pharmacology
  • Animals
  • Cell Line, Transformed
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Cytosol / drug effects
  • Cytosol / metabolism
  • Farnesol / analogs & derivatives
  • Farnesol / pharmacology
  • Growth Inhibitors / pharmacology
  • Methylation / drug effects
  • Oncogene Proteins v-raf
  • Rats
  • Receptor, ErbB-2 / pharmacology
  • Retroviridae Proteins, Oncogenic / pharmacology
  • Salicylates / pharmacology
  • ras Proteins / antagonists & inhibitors
  • ras Proteins / drug effects
  • ras Proteins / metabolism*


  • Growth Inhibitors
  • Retroviridae Proteins, Oncogenic
  • Salicylates
  • farnesylthiosalicylic acid
  • Farnesol
  • Receptor, ErbB-2
  • Oncogene Proteins v-raf
  • ras Proteins
  • N-acetyl-S-farnesylcysteine
  • Acetylcysteine