Nicotine down-regulates miR-24-1. (A) Nicotine (10 nM) down-regulates miR-24 expression in human AoSMCs via the NF-kB pathway. Down-regulation is neutralized with siRNA to RELA. (B) Nicotine (10 nM) down-regulates pri-miR-24-1 but not pri-miR-24-2 in RAW264.7 cells. (C) Nicotine reduces pri-miR-24-1 expression in RAW264.7 cells via ROS. Addition of ROS-scavenger TEMPOL leads to an increase in pri-miR-24-1 expression despite nicotine treatment. (D and E) Recombinant IL-6 treatment lowers pri-miR-24-1 in RAW264.7 cells and human AoSMCs, a process which is augmented dose-dependently by nicotine. Gene expression data are presented as fold change vs. control. *P < 0.05 vs. untreated control (A, B, and C). §P < 0.05 vs. control; §§ vs. control and IL6; † vs. control, IL6, and IL6 + Nic10 nM (D and E). All Student’s t-test. Data are mean ± SEM (n = 3–8/treatment group). Down-regulated genes are shown as −1/FC.