ABSTRACT
Libraries of nonpurified resorcinol amide derivatives were screened by surface plasmon resonance (SPR) to determine the binding dissociation constant (off-rate, kd) for compounds binding to the pyruvate dehydrogenase kinase (PDHK) enzyme. Parallel off-rate measurements against HSP90 and application of structure-based drug design enabled rapid hit to lead progression in a program to identify pan-isoform ATP-competitive inhibitors of PDHK. Lead optimization identified selective sub-100-nM inhibitors of the enzyme which significantly reduced phosphorylation of the E1α subunit in the PC3 cancer cell line in vitro.
Subject(s)
Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Adenosine Triphosphate/metabolism , Cell Line, Tumor , Drug Design , HSP90 Heat-Shock Proteins/metabolism , Humans , Male , Models, Molecular , Phosphorylation/drug effects , Prostatic Neoplasms/drug therapy , Prostatic Neoplasms/metabolism , Protein Isoforms/metabolism , Protein Serine-Threonine Kinases/metabolism , Pyruvate Dehydrogenase Acetyl-Transferring KinaseABSTRACT
Pin1 is an emerging oncology target strongly implicated in Ras and ErbB2-mediated tumourigenesis. Pin1 isomerizes bonds linking phospho-serine/threonine moieties to proline enabling it to play a key role in proline-directed kinase signalling. Here we report a novel series of Pin1 inhibitors based on a phenyl imidazole acid core that contains sub-µM inhibitors. Compounds have been identified that block prostate cancer cell growth under conditions where Pin1 is essential.
Subject(s)
Imidazoles/pharmacology , Peptidylprolyl Isomerase/antagonists & inhibitors , Caco-2 Cells , Drug Discovery , Humans , Imidazoles/chemistry , Models, Molecular , Molecular Structure , NIMA-Interacting Peptidylprolyl IsomeraseABSTRACT
Inhibitors of the Hsp90 molecular chaperone are showing considerable promise as potential chemotherapeutic agents for cancer. Here, we describe the structure-based design, synthesis, structure-activity relationships and pharmacokinetics of potent small-molecule inhibitors of Hsp90 based on the 4,5-diarylisoxazole scaffold. Analogues from this series have high affinity for Hsp90, as measured in a fluorescence polarization (FP) competitive binding assay, and are active in cancer cell lines where they inhibit proliferation and exhibit a characteristic profile of depletion of oncogenic proteins and concomitant elevation of Hsp72. Compound 40f (VER-52296/NVP-AUY922) is potent in the Hsp90 FP binding assay (IC50 = 21 nM) and inhibits proliferation of various human cancer cell lines in vitro, with GI50 averaging 9 nM. Compound 40f is retained in tumors in vivo when administered i.p., as evaluated by cassette dosing in tumor-bearing mice. In a human colon cancer xenograft model, 40f inhibits tumor growth by approximately 50%.