Aryl amide small-molecule inhibitors of microRNA miR-21 function.

MicroRNAs (miRNAs) are single stranded RNA molecules of ∼22 nucleotides that negatively regulate gene expression. MiRNAs are involved in fundamental cellular processes, such as development, differentiation, proliferation, and survival. MiRNA misregulation has been linked to various human diseases, most notably cancer. MicroRNA-21 (miR-21), a well-established oncomiR, is significantly overexpressed in many types of human cancers, thus rendering miR-21 a potential therapeutic target. Using a luciferase-based reporter assay under the control of miR-21 expression, a high-throughput screen of >300,000 compounds led to the discovery of a new aryl amide class of small-molecule miR-21 inhibitors. Structure-activity relationship (SAR) studies resulted in the development of four aryl amide derivatives as potent and selective miR-21 inhibitors. The intracellular levels of various miRNAs in HeLa cells were analyzed by qRT-PCR revealing specificity for miR-21 inhibition over other miRNAs. Additionally, preliminary mechanism of action studies propose a different mode of action compared to previously reported miR-21 inhibitors, thus affording a new chemical probe for future studies.