AhR pathway is involved in the antiapoptotic effect of Parisian PM
. (A) 16HBE epithelial cells were preincubated or not in the presence of the agonist beta-naphtoflavone (beta-NF, 20 μg/ml) or the antagonist alpha-naphtoflavone (alpha-NF, 10 μg/ml) one hour before the usual PM2.5-AW pretreatment and/or apoptosis inducer A23187 (3 μM). Apoptosis was measured by flow cytometry as above. Results are mean ± SD (n = 3). p < 0.001, * vs. Control, # vs. A23187, § vs. A23187 + PM2.5. (B) Effect of AhR silencing. (Upper panel) 16HBE cells were incubated during 48 h with AhR siRNA (AhR, 10 nM), a control siRNA (Co, 10 nM) or non-transfected (NT), then total cell extract (80 μg) were loaded onto gel and subjected to immunoblotting with anti-AhR and anti-Actin antibodies. Quantifications were performed as respect to Actin and illustrated as AhR/Actin ratio. (Lower Graph) 16HBE cells were incubated with siRNA for 48 h as above and then 4 h pretreated to PM2.5-AW before apoptosis induction with A23187 for 20 h supplementary. Results of flow cytometry (DiOC(6)3 low and IP high) are from transfected cells (Alexa Fluor 647 positive population) which were around 80% for all conditions, illustrated as mean ± SD (n = 4). p < 0.001, * vs non-treated siRNA Co; p < 0.001, # vs. A23187 siRNA Co; p < 0.005, § vs. A23187 + PM2.5 siRNA Co.