Identification of Inhibitors of Protein Kinase B Using Fragment-Based Lead Discovery

Abstract

Using fragment-based screening techniques, 5-methyl-4-phenyl-1H-pyrazole (IC50 80 microM) was identified as a novel, low molecular weight inhibitor of protein kinase B (PKB). Herein we describe the rapid elaboration of highly potent and ligand efficient analogues using a fragment growing approach. Iterative structure-based design was supported by protein-ligand structure determinations using a PKA-PKB "chimera" and a final protein-ligand structure of a lead compound in PKBbeta itself.

AT7867 Is a Potent and Oral Inhibitor of AKT and p70 S6 Kinase That Induces Pharmacodynamic Changes and Inhibits Human Tumor Xenograft Growth

“…AT7867 was discovered using fragment-based screening combined with structure-based design and was previously called compound 8a by Saxty et al (31). The molecule is a pyrazole, linked via the 4-position to a geminally substituted 4,4-biaryl piperidine, with the terminal aromatic group incorporating a para-chloro substituent (Fig.…”

“…Recently, the PI3K/AKT signal transduction pathway has become the focus of intense interest as a critical regulator of tumor cell survival, and a number of AKT pathway inhibitors have been disclosed with a wide variety of potencies and specificities (2,44,45). In this report, we describe the in vitro and in vivo effects of AT7867, a recently developed inhibitor of AKT and p70S6K, which has been identified using fragment-based lead discovery and structure-based design technologies (29)(30)(31)(32).…”

“…All reagents were purchased from Sigma unless otherwise stated. AT7867 (31) and LY294002 (Calbiochem, Merck Biosciences) were dissolved to a 10 mmol/L stock in DMSO, whereas okadaic acid (Calbiochem, Merck Biosciences) was dissolved to a 50 μmol/L stock in DMSO. The recombinant purified AKT2 enzyme used was the pleckstrin homology-truncated AKT2 protein PKB-PIF Pif as previously described (29), which was kindly provided by Professor David Barford (Institute of Cancer Research).…”

“…These fragments were validated by structural studies and rapidly transformed into potent lead compounds using structure-based design to increase the efficiency of the medicinal chemistry. This research was recently described in detail and has identified potent, low molecular weight inhibitors of AKT that exhibit drug-like properties (29)(30)(31)(32).…”

A review of recent progress (2002-2012) on the biological activities of pyrazoles

“…From hit 190 and using a fragment growing approach, the lead 191 was obtained and it bound to the ATP pocket. 181 Compound 192 has been reported as a HCVNS5 inhibitor with an EC50 ~ 1 M. It was included in a patent application of HCVNS5 inhibitors based on homoproline and its isosteres.…”