Subdirección de Investigación Básica, Instituto Nacional de Cancerología, San Fernando No. 22, Tlalpan 14080, Mexico.
Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán 04510, Mexico.
Int J Mol Sci. 2022 Feb 17;23(4):2224. doi: 10.3390/ijms23042224.
Airborne particulate matter with a diameter size of ≤10 µm (PM) is a carcinogen that contains polycyclic aromatic hydrocarbons (PAH), which form PAH-DNA adducts. However, the way in which these adducts are managed by DNA repair pathways in cells exposed to PM has been partially described. We evaluated the effect of PM on nucleotide excision repair (NER) activity and on the levels of different proteins of this pathway that eliminate bulky DNA adducts. Our results showed that human lung epithelial cells (A549) exposed to 10 µg/cm of PM exhibited PAH-DNA adducts as well as an increase in RAD23 and XPD protein levels (first responders in NER). In addition, PM increased the levels of H4K20me2, a recruitment signal for XPA. However, we observed a decrease in total and phosphorylated XPA (Ser196) and an increase in phosphatase WIP1, aside from the absence of XPA-RPA complex, which participates in DNA-damage removal. Additionally, an NER activity assay demonstrated inhibition of the NER functionality in cells exposed to PM, indicating that XPA alterations led to deficiencies in DNA repair. These results demonstrate that PM exposure induces an accumulation of DNA damage that is associated with NER inhibition, highlighting the role of PM as an important contributor to lung cancer.
空气中直径≤10 µm（PM）的颗粒物是一种致癌物质，其中含有多环芳烃（PAH），会形成 PAH-DNA 加合物。然而，暴露于 PM 的细胞中 DNA 修复途径对这些加合物的处理方式仅部分被描述。我们评估了 PM 对核苷酸切除修复（NER）活性以及该途径消除大体积 DNA 加合物的不同蛋白水平的影响。我们的结果表明，暴露于 10 µg/cm 的 PM 的人肺上皮细胞（A549）显示出 PAH-DNA 加合物，以及 RAD23 和 XPD 蛋白水平增加（NER 的早期反应蛋白）。此外，PM 增加了 H4K20me2 的水平，这是 XPA 的募集信号。然而，我们观察到总 XPA（Ser196 位点磷酸化）和磷酸化 XPA（Ser196 位点）减少，以及磷酸酶 WIP1 增加，此外还缺乏参与 DNA 损伤清除的 XPA-RPA 复合物。此外，NER 活性测定表明暴露于 PM 的细胞中 NER 功能受到抑制，表明 XPA 改变导致 DNA 修复缺陷。这些结果表明，PM 暴露会导致 DNA 损伤的积累，这与 NER 抑制有关，突出了 PM 作为肺癌重要贡献因素的作用。
