Fig. 4

The role of MMP-3 on Nano-CuO-induced production of cleaved OPN in BEAS-2B cells and U937* macrophages. BEAS-2B cells (a and b) and U937* macrophages (c and d) were transfected with 30 nM of MMP-3 siRNA or Negative Control No. 2 siRNA. After transfection, the cells were exposed to 1 µg/mL of Nano-CuO for 12 h. The conditioned media were collected to detect the level of cleaved OPN (40 kDa N-terminal fragment) by Western blot. Equal protein loading was verified by Coomassie Brilliant Blue staining. a and c were the results of a single experiment. b and d were normalized band densitometry readings averaged from three independent experiments. Data represent mean ± SE (n = 3). * Significant difference as compared to the control group, p < 0.05; # Significant difference as compared to the Nano-CuO-treated group transfected with Negative Control No. 2 siRNA, p < 0.05