Abstract: Abstract: Objective To explore the effects and mechanism of cigarette smoke extract (CSE) on the proliferation of air⁃ way smooth muscle cells (ASMCs) and the expression of CCAAT/enhancer-binding protein (CEBPα) and calreticulin. Meth⁃ ods (1) The ASMCs were stimulated with different concentrations of CSE for twenty-four hours. According to the concentra⁃ tions of CSE， the cells were divided into control group, 2.5% CSE group, 5% CSE group and 10%CSE group. The prolifera⁃ tion of ASMCs was measured by MTT colrimetric method. The CEBPαmRNA was analyzed by RT-PCR. Western bloting as⁃ say was performed to detect the levels of CRT and CEBPα protein. (2) In 10%CSE group, transfection of the siRNA respec⁃ tively for negative control or calreticulin was performed in accordance with instructions. The cell proliferation and the expres⁃ sion of calreticulin and CEBPα were compared in negative control siRNA group and calreticulin siRNA group. Results (1) With the increasing of the concentrations of CSE, the protein expression of CEBPα decreased gradually (P＜0.05), while the proliferation of ASMCs and the protein expression of calreticulin increased (P＜0.05), but the expression of CEBPα mRNA in ASMCs showed no significant difference in groups with different concentrations of CSE (P＞0.05). (2) Under the 10%CSE, the expression of CEBPα was significantly higher in CRT siRNA group than that in negative control group (P＜0.05)， but the cell proliferation and CRT were significantly lower in the calreticulin siRNA group than those in negative control siRNA group (P＜0.05). Conclusion The CSE exposure contributes to the expression of calreticulin protein， and then inhibits the translation of CEBPα mRNA， thus promotes the proliferation of ASMCs.

Key words: myocytes, smooth muscle, cell proliferation , pulmonary disease, chronic obstructive, in vitro, cigarette
smoke extract； calreticulin； CCAAT enhancer-binding protein