<i>NRAS</i> mRNA-Degrading Bifunctional Small Molecules Induce Diverse Cellular Morphological Changes in Cancer Cells

Therapeutic targeting of the oncogenic NRAS protein, which is constitutively activated in human cancers, with small molecules is a promising yet challenging anticancer strategy. Therefore, targeting the <i>NRAS</i> mRNA poses a feasible alternative that will likely yield new biological consequences due to the new mechanism of regulation at the post-transcriptional level. We report herein the first examples of a reversely regulating <i>NRAS</i> mRNA-degrading ribonuclease targeting chimeric small molecules (<i>NRAS</i>-RIBOTAC), which were assembled by conjugating a reported 4-aminoquinazoline G4-<i>NRAS</i> binder with a biphenyl RNase L binder. Among the obtained <i>NRAS</i>-RIBOTACs, <b>5</b> impacted G4-containing <i>NRAS</i> mRNA expression while it did not significantly impact the expression of NRAS protein in MD-MB-231 cells, which could be explained by the fact that the G4-containing <i>NRAS</i> transcript only accounts for a trace amount in comparison with the dominant G4-lacking <i>NRAS</i> mRNA. Furthermore, we report here for the first time the phenotypic evaluation of RIBOTACs in the unbiased phenotypic profiling method, cell painting assay. In comparison with the monovalent ribonuclease recruiter and G4-<i>NRAS</i> mRNA binder, selected RIBOTACs showed significant activities in inducing cellular morphological changes and demonstrated a new biological performance that is reflected by the diverse cellular morphological changes in cancer cells.