Subdirección de Investigación Básica, Instituto Nacional de Cancerología, San Fernando No. 22, Tlalpan, CP 14080 México, DF, Mexico.
Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Los Reyes Iztacala, CP 54090, Tlalnepantla, Estado de México, Mexico.
Chemosphere. 2019 Nov;235:794-804. doi: 10.1016/j.chemosphere.2019.06.232. Epub 2019 Jul 1.
Particulate matter (PM) is a risk factor for lung cancer development and chromosomal missegregation and cell cycle disruptions are key cellular events that trigger tumorigenesis. We aimed to study the effect of PM (PM with an aerodynamic diameter ≤10 μm) on mitotic arrest and chromosomal segregation, evaluating the spindle assembly checkpoint (SAC) protein dynamics in the human lung A549 adenocarcinoma cell line. For this purpose, synchronized cells were exposed to PM for 24 h to obtain the frequency of micronucleated (MN) and trinucleated (TN) cells. Then, the efficiency of the mitotic arrest after PM exposure was analyzed. To elucidate the effect of PM in chromosomal segregation, the levels and subcellular localization of essential SAC proteins were evaluated. Results indicated that A549 cells exposed to PM exhibited an increase in MN and TN cells and a decrease in mitotic indexes and G2/M phase. A549 cells treated with PM showed reduced protein levels of MDC1 and NEK2 (38% and 35% respectively), which is required for MAD2 recruitment to kinetochores, MAD2 and BUBR1, effectors of the SAC (25% and 18% respectively), and CYCLIN B1, required during G2/M phase (35%). Besides, PM exposure increase the levels of AURORA B and SURVIVIN, required for SAC activation through chromosome-microtubule attachment errors (85% and 74% respectively). We suggest that PM causes mitotic slippage due to alterations in MAD2 localization. Thus, PM causes inadequate chromosomal segregation and deficient mitotic arrest by altering SAC protein levels, predisposing A549 cells to chromosomal instability, a common feature observed in cancer.
颗粒物（PM）是肺癌发展的风险因素，染色体错误分离和细胞周期紊乱是触发肿瘤发生的关键细胞事件。我们旨在研究 PM（空气动力学直径≤10μm 的 PM）对有丝分裂阻滞和染色体分离的影响，评估人肺 A549 腺癌细胞系中纺锤体组装检查点（SAC）蛋白的动力学。为此，同步化细胞暴露于 PM 24 小时以获得微核（MN）和三核（TN）细胞的频率。然后，分析 PM 暴露后有丝分裂阻滞的效率。为了阐明 PM 在染色体分离中的作用，评估了必需 SAC 蛋白的水平和亚细胞定位。结果表明，暴露于 PM 的 A549 细胞表现出 MN 和 TN 细胞增加，有丝分裂指数和 G2/M 期减少。用 PM 处理的 A549 细胞显示 MAD2 募集到动粒所需的 MDC1 和 NEK2 蛋白水平降低（分别为 38%和 35%），SAC 的效应物 MAD2 和 BUBR1（分别为 25%和 18%）以及 G2/M 期所需的 CYCLIN B1（35%）。此外，PM 暴露增加了 AURORA B 和 SURVIVIN 的水平，这是通过染色体-微管附着错误激活 SAC 所必需的（分别为 85%和 74%）。我们认为，PM 导致 MAD2 定位改变引起有丝分裂滑走。因此，PM 通过改变 SAC 蛋白水平导致染色体分离不充分和有丝分裂阻滞，使 A549 细胞易发生染色体不稳定，这是癌症中常见的特征。
