Department of Earth and Environmental Sciences, Polaris Research Centre, University of Milano-Bicocca, Piazza della Scienza, 1, 20126, Milan, Italy.
Department of Biological and Chemical Working Environment, National Institute of Occupational Health, 0033, Oslo, Norway.
Arch Toxicol. 2018 Sep;92(9):2923-2933. doi: 10.1007/s00204-018-2259-z. Epub 2018 Jul 9.
Exposure to particulate matter (PM) has been related to the onset of adverse health effects including lung cancer, but the underlying molecular mechanisms are still under investigation. Epithelial-to-mesenchymal transition (EMT) is regarded as a crucial step in cancer progression. In a previous study, we reported EMT-related responses in the human bronchial epithelial cell line HBEC3-KT, exposed to Milan airborne winter PM2.5. We also found a strong modulation of SERPINB2, encoding for the PAI-2 protein and previously suggested to play an important role in cancer. Here we investigate the role of SERPINB2/PAI-2 in the regulation of EMT-related effects induced by PM exposure in HBEC3-KT. PM exposure (up to 10 µg/cm) increased SERPINB2 expression, reduced cell migration and induced morphological alterations in HBEC3-KT. Changes in actin structure and cadherin-1 relocalization were observed in PM-exposed samples. Knockdown of SERPINB2 by siRNA down-regulated the CDH1 gene expression, as well as PAI-2 and cadherin-1 protein expression. SERPINB2 knockdown also increased cell migration rate, and counteracted the PM-induced reduction of cell migration and alteration of cell morphology. SERPINB2 was found to be greatly down-regulated in a HBEC2-KT transformed cell line, supporting the importance of this gene in the regulation of EMT. In conclusion, here we show that PAI-2 regulates CDH1 gene/cadherin-1 protein expression in bronchial HBEC3-KT cells, and this mechanism might be involved in the regulation of cell migration. SERPINB2 down-regulation should be considered part of EMT, and the over-expression of SERPINB2 in PM-exposed samples might be interpreted as an initial protective mechanism.
颗粒物（PM）暴露与包括肺癌在内的不良健康影响的发生有关，但潜在的分子机制仍在研究中。上皮-间充质转化（EMT）被认为是癌症进展的关键步骤。在之前的研究中，我们报道了暴露于米兰冬季空气 PM2.5 后人类支气管上皮细胞系 HBEC3-KT 中的 EMT 相关反应。我们还发现 SERPINB2 强烈调节，其编码 PAI-2 蛋白，先前被认为在癌症中发挥重要作用。在这里，我们研究了 SERPINB2/PAI-2 在调节 PM 暴露诱导的 HBEC3-KT 中 EMT 相关效应中的作用。PM 暴露（最高达 10μg/cm）增加了 SERPINB2 的表达，降低了细胞迁移，并诱导了 HBEC3-KT 的形态改变。在暴露于 PM 的样品中观察到肌动蛋白结构和钙粘蛋白-1 重定位的变化。siRNA 敲低 SERPINB2 下调了 CDH1 基因表达以及 PAI-2 和钙粘蛋白-1 蛋白表达。SERPINB2 敲低还增加了细胞迁移率，并抵消了 PM 诱导的细胞迁移减少和细胞形态改变。在 HBEC2-KT 转化细胞系中发现 SERPINB2 大大下调，支持该基因在 EMT 调控中的重要性。总之，我们在这里表明 PAI-2 调节支气管 HBEC3-KT 细胞中 CDH1 基因/钙粘蛋白-1 蛋白的表达，并且该机制可能参与调节细胞迁移。SERPINB2 下调应被视为 EMT 的一部分，并且 PM 暴露样品中 SERPINB2 的过度表达可以被解释为初始保护机制。
