Mirna mimic

Cells were seeded at 70-80% confluency one day before transfection. All transfections (plasmids, siRNAs or miRNA mimics) were performed using Lipofectamine2000 (LF2000) according to the manufacturer’s instructions (0.4 μL/well in 96-well plates, 4 μL/well in 6well plates and 10 μL/dish in 10 cm dishes). Cells were incubated for 48 or 72 h at 37 °C, 5% CO₂ in a humidified atmosphere before they were used for experiments.
All siRNAs (Dharmacon, Lafayette, USA) and synthesized miRNA mimics (Qiagen, Hilden, Germany) were used at a final concentration of 30 nM. The siRNAs purchased from siTOOLs Biotech (Planegg, Germany) were used at a final concentration of 2 nM. The sequences of siRNAs and miRNA mimics are listed in Additional file 2: Supplementary Table 1.

The nanodrugs consisted of magnetic nanoparticles (MN, magnetic resonance imaging moiety) conjugated to LNA ASO or miRNA mimics (Exiqon, Denmark) as a therapeutic moiety (Fig. 1). The sequences of miRNA mimics, inhibitors and scramble controls used for the synthesis of the nanodrugs are included in Supplemental Table 1. Nanoparticles with a size of ~30 nm were used for conjugation to the oligonucleotides²⁸ . Synthesis of the prototype nanodrugs have been previously described by us^{6 (link),29 (link)} and involved: (1) synthesis of dextran-coated magnetic nanoparticles^{30 (link)}; (2) conjugation of Cy5.5 fluorescent dye. The number of dyes per magnetic nanoparticle was determined as 3.2 (6); (3) conjugation of antisense LNA inhibiting oligonucleotides (ASO) or miRNA mimics through heterobifunctional linker N-succinimidyl 3-[2-pyridyldithio]-propionate (SPDP; Thermo Scientific Co., Rockford, IL) to produce MN-ASO or MN-miRNA^{31 (link)–33 (link)}. ASO-scrambled (MN-ASOscr, single stranded) and mimics-scrambled (MN-miRNAscr, double stranded) nanodrugs were also synthesized as controls. The number of oligos per MN was determined as 4.0 using the electrophoresis analysis method described previously^{33 (link)}.