Health and Environmental Risk Division, National Institute for Environmental Studies, Tsukuba 305-8506, Japan.
Health and Environmental Risk Division, National Institute for Environmental Studies, Tsukuba 305-8506, Japan.
Toxicol Appl Pharmacol. 2022 Nov 1;454:116231. doi: 10.1016/j.taap.2022.116231. Epub 2022 Sep 9.
Exposure to inorganic arsenic has been known to induce cancers in various organs, however, the underlying mechanisms remain unclear. Premature senescence refers to the irreversible growth arrest induced by stress stimuli. The senescence-associated secretory phenotype (SASP), particularly in fibroblasts, has been shown to promote cancer development. In this study, we examined whether arsenite exposure causes premature senescence and induction of SASP in liver fibroblasts using the human hepatic stellate cell line, LX-2. Exposure of LX-2 cells to 5 or 7.5 μM of sodium arsenite for 144 h induced the features of senescence in the cells, including morphological changes, growth inhibition, increased senescence-associated β-galactosidase activity, increased P21 gene expression, and decreased LAMINB1 gene expression. The mRNA expressions of SASP factors, such as MMP1, MMP3, IL-8, IL-1β, and CXCL1, were also highly upregulated. The wound healing assay revealed that the conditioned medium from LX-2 cells with arsenite-induced senescence increased the migration activity of cells of the human hepatoma cell line, Huh-7. Gene expression data of liver cancer samples from the Human Protein Atlas showed that high expression levels of the SASP factors that were upregulated in the cells with arsenite-induced senescence were strongly associated with a poor prognosis. In addition, the cellular levels of γ-H2AX, a DNA double-strand break marker, were increased by arsenite exposure, suggesting that DNA damage could contribute to premature senescence induction. These results show that arsenite exposure induces premature senescence in hepatic stellate cells and suggest that the SASP factors from the senescent cells promote hepatic carcinogenesis.
已知无机砷暴露会导致各种器官的癌症,但潜在机制仍不清楚。衰老前期是指由应激刺激引起的不可逆生长停滞。衰老相关分泌表型(SASP),特别是成纤维细胞中的 SASP,已被证明可促进癌症发展。在这项研究中,我们使用人肝星状细胞系 LX-2 研究了亚砷酸钠暴露是否会导致肝成纤维细胞发生衰老前期和诱导 SASP。将 LX-2 细胞暴露于 5 或 7.5 μM 亚砷酸钠 144 h 会诱导细胞发生衰老特征,包括形态变化、生长抑制、衰老相关β-半乳糖苷酶活性增加、P21 基因表达增加和 LAMINB1 基因表达减少。SASP 因子(如 MMP1、MMP3、IL-8、IL-1β和 CXCL1)的 mRNA 表达也高度上调。划痕愈合试验显示,亚砷酸钠诱导衰老的 LX-2 细胞的条件培养基增加了人肝癌细胞系 Huh-7 细胞的迁移活性。人类蛋白质图谱中肝癌样本的基因表达数据显示,亚砷酸钠诱导衰老的细胞中上调的 SASP 因子的高表达水平与预后不良密切相关。此外,γ-H2AX(一种 DNA 双链断裂标志物)的细胞水平因砷暴露而增加,表明 DNA 损伤可能导致衰老前期的诱导。这些结果表明亚砷酸钠暴露诱导肝星状细胞发生衰老前期,并提示衰老细胞的 SASP 因子促进肝致癌作用。