PD98059

J Biol Chem,1995 Nov 17;270(46):27489-94.

PD 098059 is a specific inhibitor of the activation of mitogen-activated protein kinase kinase in vitro and in vivo.[Pubmed: 7499206]

PD 098059 has been shown previously to inhibit the dephosphorylated form of mitogen-activated protein kinase kinase-1 (MAPKK1) and a mutant MAPKK1(S217E,S221E), which has low levels of constitutive activity (Dudley, D. T., Pang, L., Decker, S. J., Bridges, A. J., and Saltiel, A. R. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 7686-7689).
METHODS AND RESULTS:
Here we report that PD 098059 does not inhibit Raf-activated MAPKK1 but that it prevents the activation of MAPKK1 by Raf or MEK kinase in vitro at concentrations (IC50 = 2-7 microM) similar to those concentrations that inhibit dephosphorylated MAPKK1 or MAPKK1(S217E,S221E). PD 098059 inhibited the activation of MAPKK2 by Raf with a much higher IC50 value (50 microM) and did not inhibit the phosphorylation of other Raf or MEK kinase substrates, indicating that it exerts its effect by binding to the inactive form of MAPKK1. PD 098059 also acts as a specific inhibitor of the activation of MAPKK in Swiss 3T3 cells, suppressing by 80-90% its activation by a variety of agonists. The high degree of specificity of PD 098059 in vitro and in vivo is indicated by its failure to inhibit 18 protein Ser/Thr kinases (including two other MAPKK homologues) in vitro by its failure to inhibit the in vivo activation of MAPKK and MAP kinase homologues that participate in stress and interleukin-1-stimulated kinase cascades in KB and PC12 cells, and by lack of inhibition of the activation of p70 S6 kinase by insulin or epidermal growth factor in Swiss 3T3 cells. PD 098059 (50 microM) inhibited the activation of p42MAPK and isoforms of MAP kinase-activated protein kinase-1 in Swiss 3T3 cells, but the extent of inhibition depended on how potently c-Raf and MAPKK were activated by any particular agonist and demonstrated the enormous amplification potential of this kinase cascade. PD 098059 not only failed to inhibit the activation of Raf by platelet-derived growth factor, serum, insulin, and phorbol esters in Swiss 3T3 cells but actually enhanced Raf activity. The rate of activation of Raf by platelet-derived growth factor was increased 3-fold, and the subsequent inactivation that occurred after 10 min was prevented.
CONCLUSIONS:
These results indicate that the activation of Raf is suppressed and that its inactivation is accelerated by a downstream component(s) of the MAP kinase pathway.

Proc Natl Acad Sci U S A, 1995 Aug 15;92(17):7686-9.

A synthetic inhibitor of the mitogen-activated protein kinase cascade.[Pubmed: 7644477]

Treatment of cells with a variety of growth factors triggers a phosphorylation cascade that leads to activation of mitogen-activated protein kinases (MAPKs, also called extracellular signal-regulated kinases, or ERKs).
METHODS AND RESULTS:
We have identified a synthetic inhibitor of the MAPK pathway. PD 098059 [2-(2'-amino-3'-methoxyphenyl)-oxanaphthalen-4-one] selectively inhibited the MAPK-activating enzyme, MAPK/ERK kinase (MEK), without significant inhibitory activity of MAPK itself. Inhibition of MEK by PD 098059 prevented activation of MAPK and subsequent phosphorylation of MAPK substrates both in vitro and in intact cells. Moreover, PD 098059 inhibited stimulation of cell growth and reversed the phenotype of ras-transformed BALB 3T3 mouse fibroblasts and rat kidney cells.
CONCLUSIONS:
These results indicate that the MAPK pathway is essential for growth and maintenance of the ras-transformed phenotype. Further, PD 098059 is an invaluable tool that will help elucidate the role of the MAPK cascade in a variety of biological settings.

Proc Natl Acad Sci U S A,1995 Aug 15;92(17):7686-9.

A synthetic inhibitor of the mitogen-activated protein kinase cascade.[Pubmed: 7644477]

Cell lines:K-Balb, KNRK, v-raf-3Y1, SRA/3Y1, EGFR/3T3, and K562
Concentrations: Dissolved in DMSO, final concentrations ~100 μM
Incubation Time: 3 dyas, or 7-10 days
Method:
For monolayer growth, cells are plated into multi-well plates at 10,000-20,000/mL. Forty-eight hours later, various concentrations of PD98059 are added to the cell growth medium and incubation is continued for an additional 3 days. Cells are then removed from the wells by incubation with trypsin and enumerated with a Coulter Counter. For growth in soft agar, cells are seeded into 35-mm dishes at 5,000-10,000 cells per dish with growth medium containing 0.3% agar and desired concentrations of PD98059. After 7-10 days of growth, visible colonies are manually enumerated with the aid of a dissecting microscope.

Int J Immunopathol Pharmacol,Oct-Dec 2009;22(4):937-50.

Effect of PD98059, a selective MAPK3/MAPK1 inhibitor, on acute lung injury in mice.[Pubmed: 20074457]

Animal Models: Male Sprague–Dawley rats with acute pancreatitis
Dosages: 10 mg/kg
Administration: Injection i.v.