title: Rationally induced RNA:DNA G-quadruplex structures elicit an anticancer effect by inhibiting endogenous eIF-4E expression.
abstract: 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 at a physiologically relevant salt concentration. We established the specificity and efficacy of the induced GQ formation by monitoring the targeted repression of a reporter gene. Most importantly we have demonstrated that inducing GQ in the 5'-UTR and the protein coding region of eIF-4E mRNA in human cancer cells results in 30% and 60% inhibition of the endogenous protein expression, respectively. Treating with the GQ inducing oligonucleotide sequences resulted in a decrease in the viability of human cancer cells in a dose-dependent manner. The above concept opens up a new strategy for targeted modulation of endogenous gene expression.
authors: Department of Chemistry & Biochemistry, Kent State University , Kent, Ohio 44242, United States.
authors: Debmalya
authors: D
authors: Bhattacharyya
authors: Kim
authors: K
authors: Nguyen
authors: Soumitra
authors: S
authors: Basu
mesh_terms: D020121:5' Untranslated Regions; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D002942:Circular Dichroism; D039561:Eukaryotic Initiation Factor-4E / Q000037:antagonists & inhibitors / Q000235:genetics*; D054856:G-Quadruplexes; D005786:Gene Expression Regulation / Q000187:drug effects; D006367:HeLa Cells / Q000187:drug effects; D006801:Humans; D009841:Oligonucleotides / Q000737:chemistry / Q000494:pharmacology; D010957:Plasmids / Q000235:genetics; D014176:Protein Biosynthesis / Q000187:drug effects; D013696:Temperature
chemical_list: D020121:5' Untranslated Regions; D000970:Antineoplastic Agents; D039561:Eukaryotic Initiation Factor-4E; D009841:Oligonucleotides