Amino-thio-acrylonitriles as MEK inhibitors

Details Amino-thio-acrylonitriles as MEK inhibitors Amino-thio-acrylonitriles as MEK inhibitors

2000-03-17

2004-03-09

Rotman, Alan L. (Department: 1625)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Ester doai

C558S390000

Reexamination Certificate

active

06703420

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to amino-thio-acrylonitriles as MEK inhibitors, pharmaceutical compositions containing the same, and methods of using the same as for treatment and prevention of inflammatory disorders, cancer or other proliferative diseases or as a radiosensitizing agents against cancer or other proliferative disorders.
BACKGROUND OF THE INVENTION
The mitogen activated protein kinase (MAPK) signaling pathways are involved in cellular events such as growth, differentiation and stress responses (
J. Biol. Chem.
(1993) 268, 14553-14556). Four parallel pathways have been identified to date ERK1/ERK2, JNK, p38 and ERK5. These pathways are linear kinase cascades in that MAPKKK phosphorylates and activates MAPKK that phosphorylates and activates MAPK. To date, there are 7 MAPKK homologs (MEK1, MEK2, MKK3, MKK4/SEK, MEK5, MKK6, and MKK7) and 4 MAPK families (ERK1/2, JNK, p38, and ERK5). The MAPKK family members are unique in that they are dual-specific kinases, phosphorylating MAPKs on threonine and tyrosine. Activation of these pathways regulates the activity of a number of substrates through phosphorylation. These substrates include transcription factors such as TCF, c-myc, ATF2 and the AP-1 components, fos and Jun; the cell surface components EGF-R; cytosolic components including PHAS-I, p90
rsk
, cPLA
2
and c-Raf-1; and the cytoskeleton components such as tau and MAP2.
The prototypical mitogen activated protein kinase cascade is reflected by the ERK pathway (
Biochem J.
(1995) 309, 361-375). The ERK pathway is activated primarily in response to ligation of receptor tyrosine kinases (RTKs) (
FEBS Lett.
(1993) 334, 189-192). Signal propagation from the RTKs occurs down the Ras pathway through sequential phosphorylation of Raf, MEK and ERK. This pathway has not been typically viewed of as an important contributor to the inflammatory response, but rather involved in growth and differentiation processes. This view stems from the profile of typical activators of this pathway, which include growth factors (PDGF, NGF, EGF), mitogens (phorbol esters), and polypeptide hormones (insulin, IGF-1). Evidence for ERK pathway involvement in inflammatory and immune responses has, however, gained some support in recent years (
Proc. Natl. Acad. Sci. USA.
(1995) 92, 1614-1618;
J. Immunol.
(1995) 155, 1525-1533; and
J. Biol. Chem.
(1995) 270, 27391-27394). Cytokines such as TNFa and IL-1b, the bacterial cell wall mitogen, LPS, and chemotactic factors such as fMLP, C5a, and IL-8 all activate the ERK pathway. In addition, the ERK pathway is activated as a result of T cell receptor ligation with antigen or agents such as PMA/ionomycin or anti-CD3 antibody, which mimic TCR ligation in T cells (
Proc. Natl. Acad. Sci. USA
(1995) 92, 7686-7689). These findings indicate that inhibitors of the ERK pathway should function as anti-inflammatory and immune suppressive agents.
Small molecule inhibitors of the Raf/MEK/ERK pathway have been identified. A series of benzoquinones has been disclosed by Parke-Davis, which is exemplified by PD 098059 that inhibits MEK activity (
J. Biol. Chem.
(1995) 46, 27498-27494). Recently, we identified a MEK inhibitor, U0126 (
J. Biol. Chem.
(1998) 29, 18623-18632). Comparative kinetic analysis showed that U0126 and PD 098059 were non-competitive inhibitors of activated MEK (
J. Biol. Chem.
(1998) 29, 18623-18632). These MEK inhibitors have been used to investigate the role of the ERK activation cascade in a wide variety of systems including inflammation, immune suppression and cancer. For example, PD 098059 blocks thymidine incorporation into DNA in PDGF-stimulated Swiss 3T3 cells (
J. Biol. Chem.
(1995) 46, 27498-27494). PD 098059 also prevents PDGF-BB-dependent SMC (Smooth Muscle Cell) chemotaxis at concentrations which inhibit ERK activation (
Hypertension
(1997) 29, 334-339). Similarly, U0126 prevents PDGF-dependent growth of serum starved SMC. We have also shown that U0126 blocks keratinocyte proliferation in response to a pituitary growth factor extract, which consists primarily of FGF. These data coupled with those obtained with PD 098059 above indicate that MEK activity is essential for growth factor-stimulated proliferation.
The role of the MEK/ERK pathway in inflammation and immune suppression has been examined in a number of systems, including models of T cell activation. The T cell antigen receptor (TCR) is a non-RTK receptor whose intracellular signaling pathways have been elucidated (
Proc. Natl. Acad. Sci. USA
(1995) 92, 7686-7689). DeSilva et al. have generated a great deal of information with U0126 in T cell systems (
J. Immunol.
(1998) 160, 4175-4181). Their data showed that U0126 prevents ERK activation in T cells in response to PMA/ionomycin, Con A stimulation, and antigen in the presence of costimulation. In addition, T cell activation and proliferation in response TCR engagement is blocked by U0126 as is IL-2 synthesis. These results indicate that MEK inhibition does not result in a general antiproliferative effect in this IL-2-driven system, but selectively blocks components of the signaling cascades initiated by T cell receptor engagement.
PD 098059 has also been shown to inhibit T cell proliferation in response to anti-CD3 antibody, which is reversed by IL-2 (
J. Immunol.
(1998) 160, 2579-2589.). PD 098059 also blocked IL-2 production by T cells stimulated with anti-CD3 antibody in combination with either anti-CD28 or PMA. In addition, the MEK inhibitor blocked TNFa, IL-3 GM-CSF, IFN-g, IL-6 and IL-10 production. In contrast, PD 098059 enhanced production of IL-4, IL-5 and IL-13 in similarly stimulated T cell cultures. These differential T cells effects with MEK inhibition suggest that therapeutic manipulations may be possible.
Neutrophils show ERK activation in response to the agonists N-formyl peptide (fMLP), IL-8, C5a and LTB
4
, which is blocked by PD 098059 (
Biochem. Biophy. Res. Commun.
(1997) 232, 474-477). Additionally, PD 098059 blocks neutrophil chemotaxis in response to all agents, but does not alter superoxide anion production. However, fMLP-stimulated superoxide generation was inhibited by PD098059 in HL-60 cells (
J. Immunol.
(1997) 159, 5070-5078), suggesting that this effect may be cell-type specific. U0126 blocks ERK activation in fMLP- and LTB
4
-stimulated neutrophils, but does not impair NADPH-oxidase activity or bacterial cell killing. U0126 at 10 mM blunts up regulation of b2 integrin on the cell surface by 50% and blocks chemotaxis through a fibrin gel >80% in response to IL-8 and LTB
4
. Thus, neutrophil mobility is affected by MEK inhibition although the acute functional responses of the cell remain intact.
Eicosanoids are key mediators of the inflammatory response. The proximal event leading to prostaglandin and leukotriene biosynthesis is arachidonic acid release from membrane stores, which is mediated largely through the action of cytosolic phospholipase A
2
(cPLA
2
). Activation of cPLA
2
requires Ca
2+
along with phosphorylation on a consensus MAP kinase site, Ser505, which increases catalytic efficiency of the enzyme (
J. Biol. Chem.
(1997) 272, 16709-16712). In neutrophils, mast cells, or endothelial cells, PD 098059 blocks arachidonic acid release in response to opsonized zymosan, aggregation of the high affinity IgG receptor, or thrombin, respectively. Such data support a role for ERK as the mediator of cPLA
2
activation through phosphorylation (
FEBS Lett.
(1996) 388, 180-184.
Biochem J.
(1997) 326, 867-876 and
J. Biol. Chem.
(1997) 272, 13397-13402). Similarly, U0126 is able to block arachidonic acid release along with prostaglandin and leukotriene synthesis in keratinocytes stimulated with a variety of agents. Thus, the effector target, cPLA
2
, is sensitive to MEK inhibition in a variety of cell types.
MEK inhibitors also seem to affect eicosanoid production through means other than inhibition of arachidonic acid release. PD 098059 partially blocked LPS-induced Cox-2 expression in RAW 264.7 cells, indicating ERK activation alone may not be

Affiliated with

Also associated with

Rating

Amino-thio-acrylonitriles as MEK inhibitors does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Amino-thio-acrylonitriles as MEK inhibitors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Amino-thio-acrylonitriles as MEK inhibitors will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3283967