Potent aromatase inhibitors and molecular mechanism of inhibitory action.

Estrogen is a significant factor in the maintenance and progression of hormone-dependent breast cancer. As well known, aromatase mediates the production of estrogen. Thus, inhibition of aromatase with chemical molecules has been considered to be an effective treatment for estrogen receptor-positive (ER+) breast cancer. In this work, we designed and synthesized a series of novel non-steroidal molecules containing 2-phenylindole scaffold and moiety of either imidazole or 1,2,4-triazole to enhance their binding capacity with the aromatase. Among these molecules, a compound named as 8o was confirmed experimentally to have the highest inhibitory activity to aromatase. Further cell activity assay proved that compound 8o has low cytotoxicity and is a promising lead for developing novel aromatase inhibitors. Molecular modeling and simulation techniques were performed to identify the binding modes of letrozole and 8o with the aromatase. Analysis of energy of the two compound-aromatase complexes revealed that the 8o has low binding energy (strong binding affinity) to the aromatase as compared to letrozole, which was in accordance with the experimental results. As concluded, a combination of experimental and computational approaches facilitates us to understand the molecular mechanism of inhibitory action and discover more potent non-steroidal AIs against aromatase, thereby opening up a novel therapeutic strategy for hormone-dependent breast cancer.