Search

Neuroblastoma RAS (NRAS) is an oncogene that is deregulated and highly mutated in cancers including melanomas and acute myeloid leukemias. The 5′ untranslated region (UTR) (5′ UTR) of the NRAS mRNA contains a G-quadruplex (G4) that regulates translation. Here we report a novel class of small molecule that binds to the G4 structure located in the 5′ UTR of the NRAS mRNA. We used a small molecule microarray screen to identify molecules that selectively bind to the NRAS -G4 with submicromolar affinity. One compound inhibits the translation of NRAS in vitro but showed only moderate effects on the NRAS levels in cellulo. Rapid Amplification of cDNA Ends and RT-PCR analysis revealed that the predominant NRAS transcript does not possess the G4 structure. Thus, although NRAS transcripts lack a G4 in many cell lines the concept of targeting folded regions within 5′ UTRs to control translation remains a highly attractive strategy. [Display omitted] • SMMs enable identification of a lead compound which binds to a G4 in the NRAS mRNA • Chemical inhibition of translation by targeting G4 in the 5 ′ -UTR of the NRAS mRNA • Analysis indicates heterogeneity in in the length of the NRAS mRNA 5′-UTR Balaratnam et al. used a high throughput small molecule microarray screen to identify novel small molecules that block translation by binding to a G-quadruplex structure from the NRAS mRNA. Detailed chemical, biophysical, structural, and biological evaluation provide insights into both the structure and targetability of this cancer-associated mRNA, revealing transcript heterogeneity as a challenge to targeting NRAS translation. [ABSTRACT FROM AUTHOR]

MicroRNA families are ubiquitous in the human transcriptome, yet targeting of individual members is challenging because of sequence homology. Many secondary structures of the precursors to these miRNAs (pri- and pre-miRNAs), however, are quite different. Here, we demonstrate both in vitro and in cellulis that design of structure-specific small molecules can inhibit a particular miRNA family member to modulate a disease pathway. The miR-200 family consists of five miRNAs, miR-200a, -200b, -200c, -141, and -429, and is associated with type 2 diabetes (T2D). We designed a small molecule that potently and selectively targets pre-miR-200c's structure and reverses a pro-apoptotic effect in a pancreatic β cell model. In contrast, an oligonucleotide targeting the RNA's sequence inhibited all family members. Global proteomics and RNA sequencing analyses further demonstrate selectivity for miR-200c. Collectively, these studies establish that miR-200c plays an important role in T2D, and small molecules targeting RNA structure can be an important complement to oligonucleotides. [Display omitted] • A small molecule can selectively target an individual microRNA in a cluster • Selective base pair binders enhance the affinity of RNA structure-targeting molecules • Inhibition of miR-200c represses pancreatic β cell apoptosis observed in T2D microRNA (miR)-200c, part of a microRNA family with significant sequence homology, is associated with type 2 diabetes (T2D). This sequence homology makes selective inhibition of miR-200c difficult. Haniff and Liu et al. exploit structural differences to inhibit miR- 200c's biogenesis selectively with a small molecule, defining its pathway in T2D. [ABSTRACT FROM AUTHOR]