Troglitazone (Tro) reverses TGF-β1-induced EMT in primary AEC.

A. Following treatment with TGF-β1 starting on day 2 for 6 days, ZO-1 immunoreactivity was markedly decreased while α-SMA was robustly expressed, reflecting that cells are undergoing EMT (ii,vi). Following subsequent treatment with troglitazone for an additional 6 days (from day 8 through day 14), ZO-1 expression was restored and α-SMA returned to control levels (iv, viii). Nuclei are labeled with DAPI. Cells treated with TGF-β1 vehicle (i,v) serve as negative control. TGF-β1 removal (iii, vi) only shows partial reversal of EMT. B. Treatment with increasing amounts of TGF-β1 (2.5–10 ng/ml) in the presence of troglitazone (10 µM) does not prevent inhibitory effects of troglitazone on TGF-β1-induced α-SMA expression. These data are representative of three separate experiments. C. Treatment with increasing amounts of troglitazone (2.5–10 µM) in the presence of TGF-β1 (2.5 ng/ml) for 2 hours reduced phosphorylation of Smad2 and Smad3 induced by TGF-β1. These data are representative of two separate experiments.