HSP90 inhibition enhances antimitotic drug-induced mitotic arrest and cell death in preclinical models of non-small cell lung cancer.

HSP90 inhibitors are currently undergoing clinical evaluation in combination with antimitotic drugs in non-small cell lung cancer (NSCLC), but little is known about the cellular effects of this novel drug combination. Therefore, we investigated the molecular mechanism of action of IPI-504 (retaspimycin HCl), a potent and selective inhibitor of HSP90, in combination with the microtubule targeting agent (MTA) docetaxel, in preclinical models of NSCLC. We identified a subset of NSCLC cell lines in which these drugs act in synergy to enhance cell death.

PI3K-δ and PI3K-γ inhibition by IPI-145 abrogates immune responses and suppresses activity in autoimmune and inflammatory disease models.

Phosphoinositide-3 kinase (PI3K)-δ and PI3K-γ are preferentially expressed in immune cells, and inhibitors targeting these isoforms are hypothesized to have anti-inflammatory activity by affecting the adaptive and innate immune response. We report on a potent oral PI3K-δ and PI3K-γ inhibitor (IPI-145) and characterize this compound in biochemical, cellular, and in vivo assays. These studies demonstrate that IPI-145 exerts profound effects on adaptive and innate immunity by inhibiting B and T cell proliferation, blocking neutrophil migration, and inhibiting basophil activation.

Synthetic silvestrol analogues as potent and selective protein synthesis inhibitors.

Misregulation of protein translation plays a critical role in human cancer pathogenesis at many levels. Silvestrol, a cyclopenta[b]benzofuran natural product, blocks translation at the initiation step by interfering with assembly of the eIF4F translation complex. Silvestrol has a complex chemical structure whose functional group requirements have not been systematically investigated.

Hsp90 (heat shock protein 90) inhibitor occupancy is a direct determinant of client protein degradation and tumor growth arrest in vivo.

Several Hsp90 (heat shock protein 90) inhibitors are currently under clinical evaluation as anticancer agents. However, the correlation between the duration and magnitude of Hsp90 inhibition and the downstream effects on client protein degradation and cancer cell growth inhibition has not been thoroughly investigated. To investigate the relationship between Hsp90 inhibition and cellular effects, we developed a method that measures drug occupancy on Hsp90 after treatment with the Hsp90 inhibitor IPI-504 in living cells and in tumor xenografts.

Diversity-oriented synthesis of a cytisine-inspired pyridone library leading to the discovery of novel inhibitors of Bcl-2.

Four enantiopure cytisine-inspired scaffolds can be accessed via a versatile pyrrolidine template derived from a stereocontrolled [3+2] azomethine ylide-alkene cycloaddition. Differential ester protection allows for the selective formation of either a bridged bicyclic or tricyclic scaffold via pyridone cyclization. Solid-phase diversification of the pyridone scaffolds yielded a diverse library of 15,000 compounds enabling the discovery of a novel class of Bcl-2 inhibitors.

Cell-based high-throughput screening assay system for monitoring G protein-coupled receptor activation using beta-galactosidase enzyme complementation technology.

A novel cell-based functional assay to directly monitor G protein-coupled receptor (GPCR) activation in a high-throughput format, based on a common GPCR regulation mechanism, the interaction between beta-arrestin and ligand-activated GPCR, is described. A protein-protein interaction technology, the InteraX trade mark system, uses a pair of inactive beta-galactosidase (beta-gal) deletion mutants as fusion partners to the protein targets of interest. To monitor GPCR activation, stable cell lines expressing both GPCR- and beta-arrestin-beta-gal fusion proteins are generated.