Abstract
Three novel, synthetic biarylheterocycles bearing imidazole terminal groups were discovered with extreme potency (IC50 16–640 nM) against the drug‐resistant (Mitomycin C and EO9) colon carcinoma cell line BE, and also the human ovarian carcinoma A2780 and human non‐small cell lung cancer H460 cell lines. Notably, this biological activity was independent of duplex DNA binding affinity. The compounds were tested in the NCI 60‐cell line panel and COMPARE analysis suggests they are targeting the product of a ‘gene‐like sequence’ of unidentified function.
The identity of the target proteins was explored using an affinity chromatography proteomic strategy. Bespoke affinity matrices were prepared in which test compounds were attached to a solid support through a biotin tag. A synthetic route to compounds containing a biotin moiety in place of one of the imidazole sidechains was developed. Chemosensitivity studies confirmed that the biotinylated compounds retain their activity (IC50 6.25 µM in a susceptible cell line, compared with > 100 µM for an insensitive cell line).
The biotinylated ligands were exposed to protein extracts from the susceptible cell lines and ligand‐protein complexes collected using a streptavidin‐activated affinity column. Bound proteins were eluted from the column and separated using SDS‐PAGE. Proteins were characterised by MALDI MS/MS and identified using database searches.
In parallel, the mechanism of action of the compound series has been investigated using NCI 3D MIND data mining. This suggests the mechanisms of action to be associated with phosphatase‐ and kinase‐mediated cell cycle regulation.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A204.
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