Figure 1.

Differential Induction of Growth Inhibition and IFN-β Expression by 2′F-Modified 5′ppp RNAs in a Structure-Dependent Manner

2′F pyrimidine-incorporated 5′ppp RNAs were designed and generated to contain 5′ppp and various secondary structures, including a 3′ overhang hairpin (ICR1, ICR1A, ICR1B, and ICR1C), a blunt-ended hairpin (ICR2–3, ICR2, ICR2A, and ICR2B), a 5′ overhang hairpin (ICR3, ICR3A, ICR3B, and ICR3C), and multiple stem-loops (ICR4, ICR4A, and ICR5) at various lengths. Linear 5′ppp ssRNA (ICR-L) and long dsRNA (pIC) were also generated. The RNA secondary structure was predicted using mFold (http://mfold.rna.albany.edu/?q=mfold/RNA-Folding-Form). To treat cancer cells with these RNAs, WM266-4 human melanoma cells (1 × 10⁴ cells/well) were transfected for 4 hr with the indicated concentrations of RNAs in a 96-well plate. 72 hr after RNA treatment, cells and culture supernatants were harvested and analyzed for growth inhibition and IFN-β expression, respectively. The data represent two individual experiments. Error bars show SD.