Benzodiazepine peptidomimetic BZA-5B interrupts the MAP kinase activation pathway in H-Ras-transformed Rat-1 cells, but not in untransformed cells.
A benzodiazepine peptidomimetic, BZA-5B, inhibits farnesylation of H-Ras and normalizes the morphology of Rat-1 cells transformed with H-RasV12 at concentrations that do not affect the growth of untransformed Rat-1 cells. In the current experiments, we show that BZA-5B decreases the active forms of enzymes in the mitogen-activated protein (MAP) kinase signaling cascade, including Raf, MAP kinase kinase (MEK), and MAP kinase, in cells transformed with H-RasV12. BZA-5B had no effect on these enzymes in cells transformed with H-RasV12,L189, which is geranylgeranylated rather than farnesylated. In cells transformed with H-RasV12, BZA-5B reduced the activities of enzymes in the MAP kinase pathway at concentrations that only partially blocked farnesylation of H-RasV12, suggesting that nonfarnesylated H-RasV12 is a dominant inhibitor of the action of farnesylated H-RasV12 in the BZA-5B treated cells. In untransformed Rat-1 cells, BZA-5B did not inhibit MAP kinase activity nor did it prevent the acute activation triggered by epidermal growth factor, even though farnesylated endogenous H-Ras was no longer detectable. These data raise the possibility that untransformed cells contain a form of Ras (K-Ras or N-Ras) whose prenylation is not inhibited by BZA-5B, thus allowing them to resist the effects of BZA-5B.
James
G L
GL
Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.
Brown
M S
MS
Cobb
M H
MH
Goldstein
J L
JL
D000818:Animals; D001569:Benzodiazepines / Q000494:pharmacology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066298:In Vitro Techniques; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D009842:Oligopeptides / Q000494:pharmacology*; D015689:Oncogene Protein p21(ras) / Q000235:genetics; D010766:Phosphorylation; D017368:Protein Prenylation; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection
C090156:BZA 5B; D009842:Oligopeptides; D011518:Proto-Oncogene Proteins; D001569:Benzodiazepines; D004815:Epidermal Growth Factor; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020929:Mitogen-Activated Protein Kinase Kinases; D015689:Oncogene Protein p21(ras); D016283:Proto-Oncogene Proteins p21(ras)