ABSTRACT
Ruthenium catalyzed 1,3-cycloaddition (click chemistry) of an azido moiety installed on dihydroxycumene scaffold with differently substituted aryl propiolates gave a new family of 1,4,5-trisubstituted triazole carboxylic acid derivatives that showed high affinity toward Hsp90 associated with cell proliferation inhibition, both in nanomolar range. The 1,5 arrangement of the resorcinol, the aryl moieties, and the presence of an alkyl (secondary) amide in position 4 of the triazole ring were essential to get high activity. Docking simulations suggested that the triazoles penetrate the Hsp90 ATP binding site. Some 1,4,5-trisubstituted triazole carboxamides induced dramatic depletion of the examined client proteins and a very strong increase in the expression levels of the chaperone Hsp70. In vitro metabolic stability and in vivo preliminary studies on selected compounds have shown promising results comparable to the potent Hsp90 inhibitor NVP-AUY922. One of them, (compound 18, SST0287CL1) was selected for further investigation as the most promising drug candidate.
Subject(s)
Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacology , HSP90 Heat-Shock Proteins/antagonists & inhibitors , Triazoles/chemical synthesis , Triazoles/pharmacology , Animals , Antineoplastic Agents/metabolism , Blotting, Western , Catalysis , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Computational Biology , Flow Cytometry , HSP90 Heat-Shock Proteins/metabolism , Humans , Indicators and Reagents , Isoxazoles/chemical synthesis , Isoxazoles/pharmacology , Mice , Models, Molecular , Protein Binding , Resorcinols/chemical synthesis , Resorcinols/pharmacology , Ruthenium , Spectrometry, Fluorescence , Structure-Activity Relationship , X-Ray Diffraction , Xenograft Model Antitumor AssaysABSTRACT
A structural investigation on the isoxazole scaffold led to the discovery of 3,4-isoxazolediamide compounds endowed with potent Hsp90 inhibitory properties. We have found that compounds possessing a nitrogen atom directly attached to the C-4 heterocycle ring possess in vitro Hsp90 inhibitory properties at least comparable to those of the structurally related 4,5-diarylisoxazole derivatives. A group of compounds from this series of diamides combine potent binding affinity and cell growth inhibitory activity in both series of alkyl- and aryl- or heteroarylamides, with IC50 in the low nanomolar range. The 3,4-isoxazolediamides were also very effective in causing dramatic depletion of the examined client proteins and, as expected for the Hsp90 inhibitors, always induced a very strong increase in the expression levels of the chaperone Hsp70. In vivo studies against human epidermoid carcinoma A431 showed an antitumor effect of morpholine derivative 73 comparable to that induced by the reference compound 10.
