Efficient NMR Screening Approach to Discover Small Molecule Fragments Binding Structured RNA

Small molecules targeting microRNAs: new opportunities and challenges in precision cancer therapy

Noncoding RNAs, especially miRNAs, play a pivotal role in cancer initiation and metastasis, underscoring their susceptibility to precise modulation via small molecule inhibitors. This review examines the innovative strategy of targeting oncogenic miRNAs with small drug-like molecules, an approach that can reshape the cancer treatment landscape. We review the current understanding of the multifaceted roles of miRNAs in oncogenesis, highlighting emerging therapeutic paradigms that have the potential to expand cancer treatment options. As research on small molecule inhibitors of miRNA is still in its early stages, ongoing investigative efforts and the development of new technologies and chemical matter are essential to fulfill the significant potential of this innovative approach to cancer treatment.

Fragment-Based Approaches to Identify RNA Binders

Although fragment-based drug discovery (FBDD) has been successfully implemented and well-explored for protein targets, its feasibility for RNA targets is emerging. Despite the challenges associated with the selective targeting of RNA, efforts to integrate known methods of RNA binder discovery with fragment-based approaches have been fruitful, as a few bioactive ligands have been identified. Here, we review various fragment-based approaches implemented for RNA targets and provide insights into experimental design and outcomes to guide future work in the area. Indeed, investigations surrounding the molecular recognition of RNA by fragments address rather important questions such as the limits of molecular weight that confer selective binding and the physicochemical properties favorable for RNA binding and bioactivity.

Contemporary Progress and Opportunities in RNA-Targeted Drug Discovery

The surprising discovery that RNAs are the predominant gene products to emerge from the human genome catalyzed a renaissance in RNA biology. It is now well-understood that RNAs act as more than just a messenger and comprise a large and diverse family of ribonucleic acids of differing sizes, structures, and functions. RNAs play expansive roles in the cell, contributing to the regulation and fine-tuning of nearly all aspects of gene expression and genome architecture. In line with the significance of these functions, we have witnessed an explosion in discoveries connecting RNAs with a variety of human diseases. Consequently, the targeting of RNAs, and more broadly RNA biology, has emerged as an untapped area of drug discovery, making the search for RNA-targeted therapeutics of great interest. In this Microperspective, I highlight contemporary learnings in the field and present my views on how to catapult us toward the systematic discovery of RNA-targeted medicines.

Drug-Like Small Molecules That Inhibit Expression of the Oncogenic MicroRNA-21

We report the discovery of drug-like small molecules that bind specifically to the precursor of the oncogenic and pro-inflammatory microRNA-21 with mid-nanomolar affinity. The small molecules target a local structure at the Dicer cleavage site and induce distinctive structural changes in the RNA, which correlate with specific inhibition of miRNA processing. Structurally conservative single nucleotide substitutions eliminate the conformational change induced by the small molecules, which is also not observed in other miRNA precursors. The most potent of these compounds reduces cellular proliferation and miR-21 levels in cancer cell lines without inhibiting kinases or classical receptors, while closely related compounds without this specific binding activity are inactive in cells. These molecules are highly ligand-efficient (MW < 330) and display specific biochemical and cellular activity by suppressing the maturation of miR-21, thereby providing an avenue toward therapeutic development in multiple diseases where miR-21 is abnormally expressed.

Fragment-to-Lead Medicinal Chemistry Publications in 2021

This Perspective is the seventh in an annual series that summarizes successful Fragment-to-Lead (F2L) case studies published in a given year. A tabulated summary of relevant articles published in 2021 is provided, and features such as target class, screening methods, and ligand efficiency are discussed, both for the 2021 examples and for the combined examples over the years 2015-2021. In addition, trends and new developments in the field are summarized. In particular, the use of structural information in fragment-based drug discovery is discussed.

A Fluorescent Reverse-Transcription Assay to Detect Chemical Adducts on RNA

Herein, we detail a novel reverse-transcription (RT) assay to directly detect chemical adducts on RNA. We optimize a fluorescence quenching assay to detect RT polymerization and employ our approach to detect N¹-alkylation of inosine, an important post-transcriptional modification, using a phenylacrylamide as a model compound. We anticipate our approach can be expanded to identify novel reagents that form adducts with RNA and further explored to understand the relationship between RT processivity and natural post-transcriptional modifications in RNA.