Design and synthesis of small molecules targeting pre-miRNA21 toward the development of ribonuclease targeting chimeras (RIBOTACs) to regulate the oncogenic miRNA21

RNA has become a promising target for small-molecule drug discovery due to its complex structures, which provide accessible binding sites.a Among these, pre-miRNA-21, a non-coding RNA associated with various cancers and diseases, is a validated therapeutic target.b This project focuses on developing selective binders for pre-miRNA-21 to reduce miRNA-21 levels. We started with screening over 35 compounds using high-resolution native mass spectrometry (HR-MS) to identify the best candidates based on their binding affinity to pre-miRNA-21, guiding structure-activity relationship studies. Simultaneously, we are employing RIBOTAC technology, which utilizes small molecule "warheads" conjugated to RNA binders to recruit RNase L for RNA degradation. The formation of a ternary complex between the RNA, RIBOTAC, and RNase L induces selective degradation of the target RNA.c [Figure 1] To date, we have synthesized over six RIBOTACs. Ongoing studies are assessing the affinity, selectivity, and miRNA-21 maturation inhibition of these warheads using biophysical methods, such as NMR, along with enzymatic assays and cell lysates.4 In parallel, we are conducting in-cell assays to characterize phenotypic outcomes and further understand the therapeutic potential of the RIBOTACs. Through this integrated approach, we aim to identify the optimal inhibitor and miRNA-21 degrader, advancing RNA-targeted therapeutics.