| Abstract: |
High throughput screening identified 2-acetamido-thiazolylthio acetic ester 1 as an inhibitor of cyclin-dependent kinase 2 (CDK2). Because this compound is inactive in cells and unstable in plasma, we have stabilized it to metabolic hydrolysis by replacing the ester moiety with a 5-ethyl-substituted oxazole as in compound 14. Combinatorial and parallel synthesis provided a rapid analysis of the structure-activity relationship (SAR) for these inhibitors of CDK2, and over 100 analogues with IC50 values in the 1-10 nM range were rapidly prepared. The X-ray crystallographic data of the inhibitors bound to the active site of CDK2 protein provided insight into the binding modes of these inhibitors, and the SAR of this series of analogues was rationalized. Many of these analogues displayed potent and broad spectrum antiproliferative activity across a panel of tumor cell lines in vitro. In addition, A2780 ovarian carcinoma cells undergo rapid apoptosis following exposure to CDK2 inhibitors of this class. Mechanism of action studies have confirmed that the phosphorylation of CDK2 substrates such as RB, histone H1, and DNA polymerase α (p70 subunit) is reduced in the presence of compound 14. Further optimization led to compounds such as water soluble 45, which possesses a favorable pharmacokinetic profile in mice and demonstrates significant antitumor activity in vivo in several murine and human models, including an engineered murine mammary tumor that overexpresses cyclin E, the coactivator of CDK2. |
| Keywords: |
controlled study; protein expression; protein phosphorylation; unclassified drug; human cell; squamous cell carcinoma; area under the curve; nonhuman; antineoplastic agents; animal cell; mouse; animals; mice; animal tissue; cell cycle; apoptosis; enzyme inhibition; animal experiment; animal model; protein binding; in vivo study; antineoplastic activity; cancer cell culture; drug potency; drug structure; in vitro study; drug screening; drug screening assays, antitumor; tumor cells, cultured; drug synthesis; structure activity relation; structure-activity relationship; phosphorylation; mice, inbred balb c; drug mechanism; enzyme inhibitors; protein-serine-threonine kinases; breast carcinoma; ovary carcinoma; drug clearance; models, molecular; crystallography, x-ray; flavopiridol; drug bioavailability; drug blood level; ic 50; x ray crystallography; cyclin-dependent kinases; cyclin dependent kinase inhibitor; thiazoles; retinoblastoma protein; distribution volume; histones; drug protein binding; drug stability; concentration response; cyclin e; combinatorial chemistry; combinatorial chemistry techniques; enzyme active site; chemical modification; hydrophilicity; cyclin dependent kinase 2; dna directed dna polymerase alpha; dna polymerase i; cyclin-dependent kinase 2; dose time effect relation; mice, inbred dba; histone h1; oxazoles; cdc2-cdc28 kinases; humans; human; male; female; article; benzeneacetamides; drug hydrolysis; 2 acetamidothiazolylthioacetic acid ester; n [5 [[(5 ethyl 2 oxazolyl)methyl]thio] 2 thiazolyl] 3 pyridineacetamide; n [5 [[(5 ethyl 2 oxazolyl)methyl]thio] 2 thiazolyl]acetamide; n [5 [[(5 tert butyl 2 oxazolyl)methyl]thio] 2 thiazolyl] 4 [[[bis(hydroxymethyl)methyl]amino]methyl]benzeneacetamide; leukemia p 388
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