地塞米松抑制人肺成纤维细胞增殖和丝裂原活化蛋白激酶信号转导途径

目的探讨地塞米松对人肺成纤维细胞周期和丝裂原活化蛋白激酶(MAPK)信号转导通路的作用.方法不同浓度的地塞米松作用于培养的人肺成纤维细胞,采用直接计数法测定细胞的增殖,PI(propidium iodide)染色流式细胞仪分析细胞周期和细胞凋亡,用特异的抗磷酸化抗体、Western印迹法分别检测c-Jun N-末端激酶(JNK)、细胞外信号调节激酶(ERK)和p38蛋白的磷酸化,用特异的MAPK抗体分别检测相应的JNK、ERK和p38蛋白.结果1×10-7mol/L和1×10-6mol/L地塞米松抑制肺成纤维细胞增殖,4 d时细胞增殖分别减少了34%和72%,呈剂量依赖关系;地塞米松阻断肺成纤维细胞的细胞周期,G0/G1期细胞比率从(81.9±3.0)%增加到(90.1±1.4)%(P＜0.05),但地塞米松不能诱导肺成纤维细胞的凋亡;地塞米松抑制ERK的磷酸化,但不影响肺成纤维细胞中JNK和p38的激活.结论地塞米松能够抑制肺成纤维细胞的增殖,这种作用部分是通过抑制MAPK信号转导通路的ERK途径实现的,对JNK和p38途径影响较少;地塞米松不能直接诱导肺成纤维细胞的凋亡.

Inhibition of human lung fibroblast proliferation and the mitogen activated protein kinase pathway by dexamethasone

OBJECTIVE: To investigate the effects of dexamethasone on human lung fibroblast cell proliferation, cell cycles, and cell mitogen-activated protein kinases (MAPKs) passway. METHODS: Dexamethasone was used at various concentration in culture medium. Cell number was counted using a hemacytometer. Whole cell propidium iodide staining and flow cytometric analysis were performed to determine cellular DNA content. MAPK proteins and activation were tested by Western blot analysis with antibodies to c-Jun N-terminal kinase (JNK), phospho-JNK, extracellular signal-regulated kinase (ERK), phospho-ERK, p38 and phospho-p38. RESULTS: 1x10(-7) mol/L and 1x10(-6) mol/L dexamethasone suppressed the proliferation of lung fibroblast cells by 34% and 72%, respectively, than that of control. This suppression was dose-dependant. Dexamethasone suppressed cell cycle with accumulation of cells in G1/G0 stage. It increased from 81.9% to 90.1% compared with that of control. We did not find any apoptosis induced by dexamethasone for lung fibroblast cells. Using Western blot analysis, we found that dexamethasone resulted in decreased activity of ERK, but had no effects on JNK and p38. CONCLUSIONS: Dexamethasone may suppresses the proliferation of lung fibroblast cells, which is partly resulted from the facts that it can inhibit ERK activation in MAPK-signaling pathway but has little effect on JNK and p38 pathway. Dexamethasone may not induce lung fibroblast cell apoptosis directly.