Fig. 1: A chemically modified siRNA provides prolonged activity.

a The t(8;21) fusion transcript RUNX1/ETO has a unique breakpoint targeted with siRE spans the fusion site, swapping two nucleotides in siRE generates a mismatch control siMM. b Chemically modified siRNAs (siRE-mod, siMM-mod) are generated by the introduction of 2’-deoxy- (2’-H), 2’-fluoro (2’-F) and 2’-methoxy (2’-Ome) ribose modifications and 3’-terminal phosphorothioate (PS). c Western blotting of RUNX1-ETO, RUNX1 and GAPDH in Kasumi-1 following RUNX1/ETO knockdown using either siRE (top) and siRE-mod (bottom). Cells were electroporated once on day 0 and cell lysates collected after 3 and 7 days. d–f Kasumi-1 cells were electroporated sequentially on days 0 and 3 with either 200 nM siMM, 200 nM siRE, 100 nM siRE-mod or no oligos (mock), d Proliferation curve of Kasumi-1 cells following RUNX1/ETO knockdown (n = 4). ln(cell number), natural logarithm of the cell number; t(d), time in days. e Western blotting showing RUNX1/ETO, RUNX1, p-RB1 T821, RB1 and GAPDH in Kasumi-1 cells on days 6, f Senescence-associated β-galactosidase (SAβGal) staining (n = 3). g Semi-solid colony formation units of Kasumi-1 cells following RUNX1/ETO knockdown, cells were seeded on day 1 following the first electroporation and colonies were counted on day 8 and replated (n = 3). h RUNX1/ETO expression level in t(8;21)-AMLs blast 3 days after electroporation with 200 nM siMM, 200 nM siRE or 100 nM siRE-mod. Significance was tested by unpaired Student’s t tests (d, f, g).