Abstract：
Fine particulate matter (PM2.5) is a risk factor for pulmonary diseases and lung cancer, and inhaled PM2.5 is mainly deposited in the bronchial epithelium. In this study, we investigated the effect of long-term exposure to low-dose PM2.5 on BEAS-2B cells derived from the normal bronchial epithelium. BEAS-2B cells chronically exposed to a concentration of 5 µg/ml PM2.5 for 30 passages displayed the phenotype promoting epithelial-mesenchymal transition (EMT) and cell invasion. Cellular internalization of exosomes (designated PM2.5 Exo) extracted from BEAS-2B cells chronically exposed to low-dose PM2.5 promoted cell invasion in vitro and metastatic potential in vivo. Hence, to identify the key players driving phenotypic alterations, we analyzed microRNA (miRNA) expression profiles in PM2.5 Exo. Five miRNAs with altered expression were selected: miRNA-196b-5p, miR-135a-2-5p, miR-3117-3p, miR-218-5p, and miR-497-5p. miR-196b-5p was the most upregulated in both BEAS-2B cells and isolated exosomes after PM2.5 exposure. In a functional validation study, genetically modified exosomes overexpressing a miR-196b-5p mimic induced an enhanced invasive phenotype in BEAS-2B cells. Conversely, miR-196b-5p inhibition diminished the PM2.5-enhanced EMT and cell invasion. These findings indicate that exosomal miR-196b-5p may be a candidate biomarker for predicting the malignant behavior of the bronchial epithelium and a therapeutic target for inhibiting PM2.5-triggered pathogenesis.
摘要：
细颗粒物（PM2.5）是肺部疾病和肺癌的危险因素，吸入性PM2.5主要沉积在支气管上皮细胞。在这项研究中,我们研究了长期暴露于低剂量PM2.5对来自正常支气管上皮的BEAS-2B细胞的影响.长期暴露于浓度为5μg/mlPM2.5的BEAS-2B细胞传代30次，表现出促进上皮-间质转化（EMT）和细胞侵袭的表型。从长期暴露于低剂量PM2.5的BEAS-2B细胞中提取的外泌体（称为PM2.5Exo）的细胞内化促进了细胞的体外侵袭和体内转移潜力。因此，为了确定驱动表型改变的关键参与者，我们分析了PM2.5Exo中的microRNA（miRNA）表达谱。选择了五种表达改变的miRNA：miRNA-196b-5p，miR-135a-2-5p,miR-3117-3p,miR-218-5p,和miR-497-5p。在PM2.5暴露后，miR-196b-5p在BEAS-2B细胞和分离的外泌体中上调幅度最大。在功能验证研究中，过表达miR-196b-5p模拟物的基因修饰外泌体在BEAS-2B细胞中诱导了增强的侵袭表型.相反，miR-196b-5p抑制减少了PM2.5增强的EMT和细胞侵袭。这些发现表明，外泌体miR-196b-5p可能是预测支气管上皮恶性行为的候选生物标志物和抑制PM2.5触发的发病机制的治疗靶标。
