Biochemical and structural characterization of a novel class of inhibitors of the type 1 insulin-like growth factor and insulin receptor kinases.
The type 1 insulin-like growth factor receptor (IGF-1R) is often overexpressed on tumor cells and is believed to play an important role in anchorage-independent proliferation. Additionally, cell culture studies have indicated that IGF-1R confers increased resistance to apoptosis caused by radiation or chemotherapeutic agents. Thus, inhibitors of the intracellular kinase domain of this receptor may have utility for the clinical treatment of cancer. As part of an effort to develop clinically useful inhibitors of IGF-1R kinase, a novel class of pyrrole-5-carboxaldehyde compounds was investigated. The compounds exhibited selectivity against the closely related insulin receptor kinase intrinsically and in cell-based assays. The inhibitors formed a reversible, covalent adduct at the kinase active site, and treatment of such adducts with sodium borohydride irreversibly inactivated the enzyme. Analysis of a tryptic digest of a covalently modified IGF-1R kinase fragment revealed that the active site Lys1003 had been reductively alkylated with the aldehyde inhibitor. Reductive alkylation of the insulin receptor kinase with one of these inhibitors led to a similarly inactivated enzyme which was examined by X-ray crystallography. The crystal structure confirmed the modification of the active site lysine side chain and revealed details of the key interactions between the inhibitor and enzyme.
Department of Medicinal Chemistry, Merck Research Laboratories, West Point, Pennsylvania 19486, USA. ian.bell@merck.com
Ian M
IM
Bell
Steven M
SM
Stirdivant
Janet
J
Ahern
J Christopher
JC
Culberson
Paul L
PL
Darke
Christopher J
CJ
Dinsmore
Robert A
RA
Drakas
Steven N
SN
Gallicchio
Samuel L
SL
Graham
David C
DC
Heimbrook
Dawn L
DL
Hall
Jin
J
Hua
Nathan R
NR
Kett
Annette S
AS
Kim
Maria
M
Kornienko
Lawrence C
LC
Kuo
Sanjeev K
SK
Munshi
Amy G
AG
Quigley
John C
JC
Reid
B Wesley
BW
Trotter
Lloyd H
LH
Waxman
Theresa M
TM
Williams
C Blair
CB
Zartman
D000447:Aldehydes / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D001894:Borohydrides / Q000737:chemistry; D002460:Cell Line; D018360:Crystallography, X-Ray; D004789:Enzyme Activation; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011758:Pyrroles / Q000737:chemistry* / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors*; D011972:Receptor, Insulin / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D012545:Schiff Bases / Q000737:chemistry; D013329:Structure-Activity Relationship
D000447:Aldehydes; D001894:Borohydrides; D010446:Peptide Fragments; D047428:Protein Kinase Inhibitors; D011758:Pyrroles; D012545:Schiff Bases; C025364:sodium borohydride; D017526:Receptor, IGF Type 1; D011972:Receptor, Insulin