Poster abstracts
Poster number 7 submitted by Grace Arhin
Identification and Characterization of Small Molecules Targeting Oncogenic Pre-miR-31
Grace Arhin (Biophysics Program, University of Michigan), Lily Haghpassand (Department of Chemistry, University of Michigan), Sarah C. Keane (Biophysics Program, Department of Chemistry, University of Michigan)
Abstract:
Abnormal levels of microRNA 31 (miR-31) is well documented in several pathological states including cancers, neurodegenerative and cardiovascular disorders. Therefore, the ability to modulate miR-31 levels in cells can have immense therapeutic potential. One promising strategy to achieve this goal involves the use of small molecule ligands to control the biogenesis of miR-31. Following transcription, primary (pri-) miR-31 is processed to form precursor (pre-) miR-31 and ultimately mature miR-31 by the enzymes Drosha/DGCR8 and Dicer/TRBP respectively. Mature miR-31 is a 22 nucleotide single stranded RNA which lacks structural complexity needed to provide binding pockets for small molecule targeting. In contrast, pre-miR-31, folds into a highly structured RNA with cavities capable of accommodating small molecule ligands. Targeting pre-miR-31 could inhibit the production of mature miR-31 by modulating its processing by the Dicer/TRBP enzyme complex.
Herein, we employed a structure-guided approach to screening for small molecule ligands to pre-miR-31. Our approach involves initial virtual screening of 1,493 drug-like small molecules from the National Cancer Institute’s DTP library against pre-miR-31’s ligandable cavities. Our virtual screening campaign identified 40 initial hits with binding energies at least two standard deviations more negative than the average binding energy of compounds in the library. We next experimentally validated ligand binding for these hits using saturation transfer difference (STD) NMR spectroscopy and identified nine compounds that bound pre-miR-31 in vitro. Heteronuclear single quantum coherence (HSQC) chemical shift mapping experiments revealed that two of these compounds bound pre-miR-31 at the Dicer/TRBP cleavage site, which may be linked to the inhibition of its maturation. We are currently evaluating if these compounds modulate the Dicer/TRBP cleavage of pre-miR-31 in vitro
Keywords: MicroRNAs, Virtual Screening, NMR