Figure 4.

G4 ligand counteracts G4‐forming oligonucleotides and enhances ISG15 induction. (a) PC3 cells were transfected with oligonucleotides or treated with Phen‐DC3 or BIBR1532 for 72 hr under 3D culture conditions. Then, RT‐qPCR was performed to quantitate ISG15 expression. The data were normalized to GPI mRNA levels. A relative expression value of 1 was defined as the expression in cells cultured under 2D conditions. Error bar indicates standard deviation (n = 3). **p < .01 as determined by the Tukey–Kramer test. (b) Effect of Phen‐DC3 on G4‐forming oligonucleotide‐mediated repression of ISG15 induction. PC3 cells were treated with Phen‐DC3 in the presence or absence of (ttaggg)4 oligonucleotide. After 72 hr, RNAs were prepared and subjected to RT‐qPCR as described in (a). (c) Effect of Phen‐DC3 on the interaction of SF3B2 with G4‐forming oligonucleotide. Biotin‐conjugated (ttaggg)12 was incubated with whole PC3 cell extracts in the presence of DMSO or Phen‐DC3 and pulled down by Dynabeads M‐280 Streptavidin. The bead‐bound proteins were subjected to Western blot analysis of SF3B2