F Chen1, R Wu, X Wang. 1. Department of Pathology, Tongji Medical College, Huazhong Science and Technology University, Wuhan 430030, China.
Abstract
OBJECTIVE: To explore the possible mechanism of injury by smoking and its repairing, the effects of cigarette smoke extract on the expression of beta-catenin (beta-cat), c-Src and level of phosphoric tyrosine in airway epithelial cells (AEC). METHODS: Pig AECs were cultured in vitro. After CSE and tyrphostin 25 exposure, (1) the expression of beta-cat was determined by immunocytochemical stain in 300 randomly selected AECs of each group, (2) the level of phosphoric tyrosine, content of c-Src and beta-cat mRNA in AECs were evaluated by immunocytochemical stain, in situ hybridization and image analysis in 30 randomly selected AECs of each group. RESULTS: After exposure to CSE for 4 hours and 24 hours, the levels of phosphoric tyrosine were 1.51 and 3.44 times of that of the control groups of the same time (P < 0.0001) respectively; the ratio of positive stain of beta-cat on membrane was markedly lower than that in the control groups (78.3% vs 83.3%, 77.7% vs 81.3%, P < 0.0001), and the cytoplasmic content of c-Src decreased 47.9% and 51.4% (P < 0.0001) compared with the control groups of the same time, respectively. While dealt with CSE and tyrphostin 25 together, the level of phosphoric tyrosine, the expression of beta-cat and c-Src resembled those in normal control. Contends of beta-cat mRNA decreased in the both two situations (P < 0.0010). CONCLUSION: CSE decreased the membranous expression of beta-cat and increased the level of tyrosine phosporylation of AECs. The change of beta-cat expression might mediate the airway epithelial injuries caused by smoking, and tyrphostin 25 might prevent such injuries through inhibiting the tyrosine kinase.
OBJECTIVE: To explore the possible mechanism of injury by smoking and its repairing, the effects of cigarette smoke extract on the expression of beta-catenin (beta-cat), c-Src and level of phosphoric tyrosine in airway epithelial cells (AEC). METHODS:Pig AECs were cultured in vitro. After CSE and tyrphostin 25 exposure, (1) the expression of beta-cat was determined by immunocytochemical stain in 300 randomly selected AECs of each group, (2) the level of phosphoric tyrosine, content of c-Src and beta-cat mRNA in AECs were evaluated by immunocytochemical stain, in situ hybridization and image analysis in 30 randomly selected AECs of each group. RESULTS: After exposure to CSE for 4 hours and 24 hours, the levels of phosphoric tyrosine were 1.51 and 3.44 times of that of the control groups of the same time (P < 0.0001) respectively; the ratio of positive stain of beta-cat on membrane was markedly lower than that in the control groups (78.3% vs 83.3%, 77.7% vs 81.3%, P < 0.0001), and the cytoplasmic content of c-Src decreased 47.9% and 51.4% (P < 0.0001) compared with the control groups of the same time, respectively. While dealt with CSE and tyrphostin 25 together, the level of phosphoric tyrosine, the expression of beta-cat and c-Src resembled those in normal control. Contends of beta-cat mRNA decreased in the both two situations (P < 0.0010). CONCLUSION: CSE decreased the membranous expression of beta-cat and increased the level of tyrosine phosporylation of AECs. The change of beta-cat expression might mediate the airway epithelial injuries caused by smoking, and tyrphostin 25 might prevent such injuries through inhibiting the tyrosine kinase.