Rapid Generation of miRNA Inhibitor Leads by Bioinformatics and Efficient High-Throughput Screening Methods.

The discovery of microRNAs (miRNAs) has opened an entire new avenue for drug development. These short (15-22 nucleotides) noncoding RNAs, which function in RNA silencing and posttranscriptional regulation of gene expression, have been shown to critically affect numerous pathways in both development and disease progression. Current miRNA drug development focuses on either reintroducing the miRNA into cells through the use of a miRNA mimic or inhibiting its function via use of a synthetic antagomir. Although these methods have shown some success as therapeutics, they face challenges particularly with regard to cellular uptake and for use as systemic reagents. We recently presented a novel mechanism of inhibiting miR-544 by directed inhibition of miRNA biogenesis. We found that inhibition of DICER processing of miR-544 through the use of a small molecule abolished miR-544 function in regulating adaptation of breast cancer cells to hypoxic stress. Herein, we describe a protocol that utilizes bioinformatics to first identify lead small molecules that bind to DICER cleavage sites in pre-miRNAs and then employ an efficient, high-throughput fluorescent-based screening system to determine the inhibitory potential of the lead compounds and their derivatives.