BMS-345541 is a highly selective inhibitor of I kappa B kinase that binds at an allosteric site of the enzyme and blocks NF-kappa B-dependent transcription in mice.
The signal-inducible phosphorylation of serines 32 and 36 of I kappa B alpha is critical in regulating the subsequent ubiquitination and proteolysis of I kappa B alpha, which then releases NF-kappa B to promote gene transcription. The multisubunit I kappa B kinase responsible for this phosphorylation contains two catalytic subunits, termed I kappa B kinase (IKK)-1 and IKK-2. BMS-345541 (4(2'-aminoethyl)amino-1,8-dimethylimidazo(1,2-a)quinoxaline) was identified as a selective inhibitor of the catalytic subunits of IKK (IKK-2 IC(50) = 0.3 microm, IKK-1 IC(50) = 4 microm). The compound failed to inhibit a panel of 15 other kinases and selectively inhibited the stimulated phosphorylation of I kappa B alpha in cells (IC(50) = 4 microm) while failing to affect c-Jun and STAT3 phosphorylation, as well as mitogen-activated protein kinase-activated protein kinase 2 activation in cells. Consistent with the role of IKK/NF-kappa B in the regulation of cytokine transcription, BMS-345541 inhibited lipopolysaccharide-stimulated tumor necrosis factor alpha, interleukin-1 beta, interleukin-8, and interleukin-6 in THP-1 cells with IC(50) values in the 1- to 5-microm range. Although a Dixon plot of the inhibition of IKK-2 by BMS-345541 showed a non-linear relationship indicating non-Michaelis-Menten kinetic binding, the use of multiple inhibition analyses indicated that BMS-345541 binds in a mutually exclusive manner with respect to a peptide inhibitor corresponding to amino acids 26-42 of I kappa B alpha with Ser-32 and Ser-36 changed to aspartates and in a non-mutually exclusive manner with respect to ADP. The opposite results were obtained when studying the binding to IKK-1. A binding model is proposed in which BMS-345541 binds to similar allosteric sites on IKK-1 and IKK-2, which then affects the active sites of the subunits differently. BMS-345541 was also shown to have excellent pharmacokinetics in mice, and peroral administration showed the compound to dose-dependently inhibit the production of serum tumor necrosis factor alpha following intraperitoneal challenge with lipopolysaccharide. Thus, the compound is effective against NF-kappa B activation in mice and represents an important tool for investigating the role of IKK in disease models.
Burke
James R
JR
Department of Immunology, Inflammation and Pulmonary Drug Discovery, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08543, USA. james.burke@bms.com
Pattoli
Mark A
MA
Gregor
Kurt R
KR
Brassil
Patrick J
PJ
MacMaster
John F
JF
McIntyre
Kim W
KW
Yang
Xiaoxia
X
Iotzova
Violetta S
VS
Clarke
Wendy
W
Strnad
Joann
J
Qiu
Yuping
Y
Zusi
F Christopher
FC
D000495:Allosteric Site; D000818:Animals; D020134:Catalytic Domain; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D051550:I-kappa B Kinase; D007093:Imidazoles / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D016328:NF-kappa B / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D011810:Quinoxalines / Q000378:metabolism / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects* / Q000502:physiology
C471109:4(2'-aminoethyl)amino-1,8-dimethylimidazo(1,2-a)quinoxaline; D004791:Enzyme Inhibitors; D007093:Imidazoles; D016328:NF-kappa B; D011810:Quinoxalines; D017346:Protein Serine-Threonine Kinases; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse