Background and objective: Recent studies have shown that integrin α5β1 as a core in the integrin family plays an important role in metastasis, invasion and poor difference of non-small cell lung cancer. In this study, A549 cells were cultured and treated with integrin α5β1 small interfering RNA (siRNA) and extracelluar signal-regulated protein kinase (ERK) inhibitor PD98059 to investigate the effect of integrin α5β1 on proliferation and migration of A549 cells and explore its signal transduction mechanism.
Methods: A549 cells were divided into four groups: Untransfection, Lipofectamine, Integrin α5β1 siRNA-transfected group and PD98059 group. The protein expression levels of integrin α5β1 were detected by Western blot analysis and the expression levels of integrin α5β1 mRNA was measured by reverse transcription-polymerase chain reaction (RT-PCR). The protein expression level of ERK1/2, MMP-9 and caspase-3 were measured by Western blot analysis. The proliferation and apoptosis of A549 cells were measured by MTT assay and Annexin-V FITC PI double staining.
Results: Integrin α5β1 siRNA could inhibit the phosphorylated ratio of ERK by down-regulate the expression of ERK 1/2 proteins. In addition, integrin α5β1 siRNA or PD98059 could inhibit the proliferation of A549 cells, induce the apoptosis of A549 cells, up-regulate the expression of caspase-3 and down-regulate the expression of MMP-9.
Conclusions: Integrin α5β1 might involves the abnormal proliferation and migration of A549 cells through mediating ERK signal transduction pathway.
背景与目的: 近年研究显示整合素α5β1作为整合素家族的重要部分与非小细胞肺癌的转移性、浸润性和低分化趋向密切相关。本研究应用整合素α5/β1 siRNA双链及ERK抑制剂PD98095干预人肺癌细胞A549，探讨整合素α5β1蛋白表达对A549细胞生长和迁移能力的影响及其细胞内信号转导机制。
方法: 实验分为未转染组、脂质体组、整合素α5β1 siRNA转染组和PD98095组四组。采用免疫印迹（Western blot）和逆转录-聚合酶链反应（RT-PCR）检测A549中整合素α5β1蛋白和mRNA表达水平，Western blot检测A549中ERK1/2、MMP-9和caspase-3蛋白水平，四甲基偶氮唑盐比色（MT）法和Annexin-V FITC PI双染色法检测A549增殖和凋亡。
结果: 整合素α5/β1 siRNA双链在抑制α5/β1蛋白和mRNA表达的同时，可以下调ERK的mRNA和蛋白表达，并抑制其磷酸化水平。整合素α5/β1 siRNA双链和PD98059均可以明显抑制A549细胞的增殖，促进细胞凋亡和细胞内caspase-3蛋白表达，并抑制细胞内MMP-9蛋白表达。
结论: 整合素α5β1可能通过介导的ERK信号转导通路参与了A549细胞的增殖和迁移调控。