NCL-targeting compound interferes with aggressiveness of breast cancer cells in vivo. (A) 10⁶ viable Luc⁺ MDA-MB-231 cells were injected into the fourth left-side mammary fat pad of female NOD-SCID mice (n = 34). 2 wk after orthotopic injections, mice with comparable visible tumors were treated with intraperitoneal injections (5 mg/kg) of AS1411 (n = 10) or control drug (DCT; n = 10) Monday through Friday for 3 wk. An additional 14 mice, treated with AS1411 as described above, were randomly divided into one group (n = 7) also treated Monday, Wednesday, and Friday for 3 wk with intratumoral injections of an miRNA pool including miR-103, miR-221, miR-222, and miR-21 and another group (n = 7) with a mixture of scrambled sequences. Once a week, the bioluminescence intensity of the injected mice was evaluated. Chart represents bioluminescence intensity (BLI) assessed every week in the four different groups of mice inoculated with 10⁶ viable Luc⁺ MDA-MB-231 cells as indicated. 2 wk after cell inoculation, mice were treated with intraperitoneal injections of AS1411 (5 mg/kg) or DCT and, where indicated, with intratumoral injection of miRNAs/Scr. 4 wk after cell inoculation, the bioluminescence intensity signal in the primary tumors reached saturation in all experimental groups. (B) Representative bioluminescence imaging after 5 wk of combined treatments showing increase of bioluminescence intensity signal in the lungs of the mice treated with control aptamer (DCT) or with intratumoral miRNA injection upon AS1411 treatment. (C) Representative hematoxylin and eosin staining of lung lesions for each group of treatments. (D) Quantification of metastatic dissemination in the different group of treatments. Analyses were performed on histological sections of the lungs (four sections per lung) for each mouse stained with hematoxylin and eosin. Horizontal bars indicate the median. *, P < 0.01. (A–D) Data are representative of three independent experiments.