Fig. 2

Effect of organic matters extracted from ambient PM on MMP expression and activity in VSMCs. a The expression levels of MMP2, 9, and 13 were analyzed by western blotting. Serum-starved VSMCs were treated with control (0.1% DMSO), PDGF-BB (20 ng/mL), SPM, or WPM at the indicated concentration for 24 h. The band densities were normalized to β-actin band density. The gel images shown are representative of those obtained from at least three independent experiments. b The mRNA levels of MMPs were quantified by qPCR. Gene expression was normalized to GAPDH. c The zymolytic activity of MMP2 was evaluated using gelatin zymography. Serum-starved VSMCs without or with NAC (1 mM) were pretreated with the designated concentrations of SPM or WPM for 24 h. PDGF treatment alone was used as a positive control. The media were then collected and used for this assay. The images shown are representative of those obtained from at least three independent experiments. d The effect of NAC on transcriptional activity of the MMP9 promoter in VSMCs was evaluated using a luciferase assay. e The expression levels of phosphorylated ERK1/2, Akt, FAK, and Src were analyzed by western blotting. Protein levels were normalized to their total levels. All values are represented as mean ± SD. *P < 0.05, **P < 0.01, and ***P < 0.001 versus control; ^#P < 0.05 WPM versus SPM; ^$P < 0.05 and ^$$$P < 0.001 PM with NAC versus PM alone; NS, no significance