Objective  To investigate the effect of exposure to particulate matter ≤ 2.5 μm in aerodynamic diameter (PM_2.5) on the expression of zinc finger E-box binding homeobox 1 (Zeb1) and Twist1 and cell proliferation in rat lung and H1299 cells.

  Methods  Totally 40 Wistar rats were treated with PM_2.5 suspension and normal saline 6 hours per day and 6 days per week for 2 and 4 weeks; then lung tissues of the rats were collected. The H1299 cells were cultured in suspension mixed with PM_2.5 at the dosages of 0, 50, 100, 200 μg/mL for 48 hours. The expression of Zeb1 and Twist1 protein in the rats' lung tissues and H1299 cells were detected with immunoblotting. The proliferation rate of H1299 cells was detected with methyl thiazolyl tetrazolium (MTT) assay.

  Results  The Zeb1 and Twist1 protein (0.27 ± 0.18 and 0.44 ± 0.15) in lung tissues of the rats exposed to PM_2.5 for 4 weeks were significantly down-regulated compared to those in control rats (0.68 ± 0.19 and 0.99 ± 0.11) (both P < 0.05). Significantly down-regulated expression of Zeb1 and Twist1 protein (0.17 ± 0.08 and 0.20 ± 0.05) were also observed in H1299 cells cultured with 200 μg/mL PM_2.5 suspension in comparison with those (1.34 ± 0.38 and 1.05 ± 0.11) in control cells (both P < 0.05); in addition, the survival rate (25.26 ± 1.84%) of H1299 cells cultured with 200 μg/mL PM_2.5 suspension for 72 hours was significantly lower than that of the control cells (P < 0.05).

  Conclusion  PM_2.5 exposure could decrease the expression of Zeb1 and Twist1 in rats' lung tissues and human lung adenocarcinoma H1299 cells and inhibit the proliferation of the H1299 cells.