Rationally Induced RNA:DNA G-Quadruplex Structures Elicit an Anticancer Effect by Inhibiting Endogenous eIF-4E Expression

RNA G-quadruplex (GQ) structures act as regulators of a diverse array of cellular processes including translation, pre-mRNA processing, and mRNA targeting. We report here a strategy of harnessing the natural ability of RNA GQs to inhibit translation by rationally inducing a GQ on a targeted mRNA to knockdown endogenous gene expression. We chose to target eIF-4E because of its key role in translation initiation and overexpression in multiple cancers and with the expectation that downregulation of eIF-4E would result in antiproliferation of cancer cells. Targeted hybrid (RNA:DNA) GQ structures were induced at the 5′-untranslated region (UTR) and the protein coding region of the eIF-4E mRNA by rationally designed and partially modified extraneous DNA sequences and their effect on eIF-4E expression was determined. The formation of a stable induced G-quadruplex was established by biophysical and biochemical methods. Thermodynamic parameters calculated from CD melting indicate formation of a stable induced GQ a...