The role of beta-catenin in the repair of the damaged airway epithelium in smoking mice]

OBJECTIVE: To evaluate the role of beta-catenin(beta-cat) in the repair of the damaged airway epithelium by comparing their expressions of beta-cat in different stages of smoking in murine model. METHODS: With HE staining, morphological changes of airway epithelium were observed microscopically in mice model at 5th week (S5 w), 10th week (S10 w) and 15th week (S15 w) of smoking. Immunohistochemistry and hybridization in situ were performed to investigate the expressions of beta-cat mRNA, beta-cat, c-Src gene and phospho-rytyrosine-protein (p-Tyr). RESULTS: Morphological changes of the airway epithelium showed predominant damage(S5 w), repair(S10 w) and excessive proliferation (S15 w) Mean beta-cat OD values at S5 w, S10 w and S15 w were 0.097 +/- 0.007, 0.160 +/- 0.003 and 0.107 +/- 0.008, being significantly lower than the control value(0.204 +/- 0.012, all P < 0.01); The mean beta-cat mRNA OD value of S5 w, S10 w and S15 w were (0.123 +/- 0.011, 0.173 +/- 0.008 and 0.116 +/- 0.004) were also lower than that in control(0.223 +/- 0.008, all P < 0.01), but the OD value of S10 w was higher than those of S5 w and S15 w. OD value of S15 w was the lowest with only traced beta-cat mRNA expression in the nuclei. The expressions of c-Src and p-Tyr in normal airway epithelium(OD values: 0.048 +/- 0.015, 0.075 +/- 0.011) were significantly lower than those in S5 w(0.127 +/- 0.018, 0.112 +/- 0.012), S10 w (0.147 +/- 0.010, 0.127 +/- 0.018) and S15 w(0.147 +/- 0.010, 0.127 +/- 0.018, all P < 0.001). CONCLUSION: beta-cat may play an important role in the process of repair of airway epithelium. Downregulation of beta-cat may be caused by c-Src which phosphorylates tyrosin residues of beta-cat, leading to its degradation; Intracellular level of p-Tyr may, to some extent, reflect the functional condition of beta-cat.