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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.

Inhibition of the ATPase activity of the chaperone protein HSP90 is a potential strategy for treatment of cancers. We have determined structures of the HSP90α N-terminal domain complexed with the purine-based inhibitor, PU3, and analogs with enhanced potency both in enzyme and cell-based assays. The compounds induce upregulation of HSP70 and downregulation of the known HSP90 client proteins Raf-1, CDK4, and ErbB2, confirming that the molecules inhibit cell growth by a mechanism dependent on HSP90 inhibition. We have also determined the first structure of the N-terminal domain of HSP90β, complexed with PU3. The structures allow a detailed rationale to be developed for the observed affinity of the PU3 class of compounds for HSP90 and also provide a structural framework for design of compounds with improved binding affinity and drug-like properties.

Multiple co-crystal structures of an adenine-based series of inhibitors bound to the molecular chaperone Hsp90 have been determined. These structures explain the observed SAR for previously described compounds and new compounds, which possess up to 8-fold improved potency against the isolated enzyme. Anti-tumour cell potency and mechanism of action data is also described for the most potent compounds. These data should enable the design of more potent Hsp90 inhibitors.

We report the reactivity of new Cβ silylated ketenimines (4, 5, 6) and lithiated-silylated ketenimine 3 leasily generated from lithiated S-methyl-N-phenyl-trimethylsilylethanimidothioate 2] toward electrophilic reagents. Reactions of these ketenimines with strong electrophilic reagents such as sulfanyl chloride (PhSCl) gave access to new sulfanylated ketenimines. With less reactive species [benzenesulfinyl chloride (PhS(O)Cl), p-toluenesulfonyl chloride, trimethylhalosilanes, diisopropyl chlorophosphate, acetyl chloride and propylene oxide] and 3, the addition took place either on Cβ or on the nitrogen atom leading to relatively unstable functionalised ketenimines or new silylated ynamines respectively.