Effects of Celecoxib on lung metastasis of lung adeno-carcinoma initiated by thoracotomy stress and the underlying mechanism

Abstract

Objective To explore the effects of Celecoxib on lung metastasis of lung adeno-carcinoma initiated by thoracotomy stress and the underlying mechanism.Methods Animal models of metastasis of lung adeno-carcinoma initiated by thoracotomy stress were created by thoracotomy and injection of lung adeno-carcinoma cell line (A549) via the lateral tail vein into BALB/c nude mice.Seventy-five nude mices were randomly divided into 3 groups:control,mice receiving thoracotomy; mice receiving thoracotomy and Celecoxib.All nude mices were injected with a suspension of 1 x 106 A549 cells via the lateral tail vein and killed at 4th week.The nodules on the lung surface were stained with 5％ picric acid and the number of nodules in each group was analyzed.In addition,the nodules were also cut into sections for hematoxylin and eosin (HE) staining to identify their pathological features.The serum prostaglandin E2 (PGE2) level was determined using the PGE2 enzyme linked immunosorbent assay (ELISA) kit at different time points.The effects of Celecoxib and PGE2 on cell migration and invasion were studied by wound healing and Transwell assay.Real-time quantitative polymerase chain reaction (Real-time PCR) and Western blotting were applied to detect the expression of matrix metalloproteinase (MMP)-2/-9,E-cadherin,GSK-3β and β-catenin in A549 cells.Results HE staining showed that the metastatic nodules of A549 cells on the lung surface were identified.The number of metastasis in mice receiving thoracotomy was greater than that in control mice (30.2 ±8.8 vs.17.2 ±5.2,P ＜0.05) and serum PGE2 level in mice receiving thoraeotomy was increased to (212.8 ±52.9) ng/L at 31st day after surgery.However,Celecoxib inhibited the increased nodules of metastases (9.1 ± 4.2) and serum PGE2 level [(102.7 ± 11.2) ng/L] respectively (P ＜0.05).PGE2 increased migration and invasion of A549 cells in the wound healing and Transwell assays,which could be reversed by Celecoxib [(177.8 ± 13.2) ％ vs.(79.8 ± 9.9) ％,P ＜ 0.01].Real-time PCR showed that mRNA expression of MMP-9 was increased by PGE. and reversed by Celecoxib,while E-cadherin was markedly decreased,and Celecoxib increased its expression.The results of Western blotting showed similar effects in the protein expression of MMP-9 and E-cadherin.Western blotting also showed that the effects of PGE2-induced increase in the protein level of β-catenin in the nucleus of A549 cells and activation of GSK-3β were significantly inhibited by Celecoxib.Conclusion Celecoxib markedly inhibits lung metastasis of lung adeno-carcinoma initiated by thoracotomy stress and the underlying mechanism may associate with inhibiting translocation of β-catenin into nucleus. Key words: Celecoxib; Surgery stress; Prostaglandin E2 ; Lung metastasis; Mechanism