Optimizing Aromatase Expression and Uncovering Novel Allosteric Inhibitors for Breast Cancer Treatment

Abstract

Breast cancer occurs in 1 of 8 women while 2,600 new cases of breast cancer are expected in men during 2016 alone1 . Aromatase, a cytochrome P450 enzyme that interconverts androgens into estrogens, is linked to hormonal breast cancer development2 . Aromatase inhibitors are currently used to treat breast cancer, but the mode of binding for some inhibitors remains unknown. The objective of this project is to optimize aromatase recombinant expression in E. coli and discover novel allosteric inhibitors. While screening possible new inhibitory compounds using an activity assay, we identified AR11 and AR13, which produced IC50 values of 25.35 μM and 0.41 μM respectively. We have not yet been successful in increasing recombinant expression of mutant-type aromatase, despite adjusting induction time, incubation temperature, and cell strain. Although optimization of aromatase expression was not achieved, possible inhibitors were uncovered which will be used in future screening of protein crystallization conditions once expression is improved. These crystal screens can then be used to generate new structures of aromatase:inhibitor complexes, leading to improved inhibitor potency and reduced toxicity.