RNA drug targets are pervasive in cells but methods to design small molecules that target them are sparse. Herein, we report a general approach to
score the affinity and selectivity of
RNA motif-
small molecule interactions identified via selection. Named High
Throughput Structure-Activity Relationships Through Sequencing (HiT-StARTS), HiT-StARTS is statistical in nature and compares input
nucleic acid sequences to selected
library members that bind a ligand via high
throughput sequencing. The approach allowed facile definition of the fitness landscape of hundreds of thousands of
RNA motif-
small molecule binding partners. These results were mined against folded RNAs in the human
transcriptome and identified an avid interaction between a
small molecule and the
Dicer nuclease-
processing site in the oncogenic
microRNA (miR)-18a hairpin precursor, which is a member of the miR-17-92 cluster. Application of the small molecule, Targapremir-18a, to
prostate cancer cells inhibited production of miR-18a from the cluster, de-repressed
serine /
threonine protein kinase 4
protein (STK4), and triggered
apoptosis. Profiling the cellular targets of Targapremir-18a via Chemical Cross Linking and isolation by Pull Down (Chem-CLIP), a covalent small molecule-RNA cellular profiling approach, and other studies showed specific binding of the compound to the miR-18a precursor, revealing broadly applicable factors that govern small molecule drugging of non-coding RNAs.