Department of Thoracic Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China.
Department of Clinical Medicine, Medical School of Nantong University, Nantong, Jiangsu 226001, P.R. China.
Int J Mol Med. 2021 Feb;47(2):573-582. doi: 10.3892/ijmm.2020.4819. Epub 2020 Dec 15.
Deoxyribonucleic acid (DNA) epigenetic modification has been linked to specific sequences of CpG islands and plays roles in the progression of lung cancer. In this study, it was found that peroxiredoxin‑5 (PRDX5) was highly expressed in non‑small cell lung cancer (NSCLC) tissues; however, its specific regulatory mechanisms and functions in NSCLC remain unknown. The present study therefore explored the regulatory mechanism of PRDX5 under conditions of oxidative stress (OS) in NSCLC. The results revealed that 79 of 121 NSCLC patients exhibited demethylation in the PRDX5 promoter region, which was related to the tumor, node and metastasis (TNM) stage (P=0.027). PRDX5 messenger ribonucleic acid (mRNA) expression positively correlated with the demethylation status of the promoter region. The results of bisulfite sequencing polymerase chain reaction (BSP) revealed lower demethylation frequencies in H1299 cells treated with 0 µM H2O2, but maximum demethylation following treatment with 100 µM H2O2. Using chromatin immunoprecipitation (ChIP) and luciferase detection assays, the effective binding of STAT3 to the transcriptional binding sites of the PRDX5 promoter region was confirmed (2 sites confirmed: Site 1, ‑444 to ‑434 bp; and site 4, ‑1,417 to ‑1,407 bp). STAT3 knockdown significantly decreased the protein expression of PRDX5, while the overexpression of STAT3 significantly increased the protein levels of PRDX5. When PRDX5 was overexpressed in lung cancer cells under conditions of OS, the levels of the epithelial‑mesenchymal transition (EMT) biomarkers, E‑cadherin and vimentin, were significantly decreased and increased, respectively. By contrast, PRDX5 knockdown resulted in significantly increased E‑cadherin and decreased vimentin protein expression levels. Ultimately, when PRDX5‑small interfering RNA (siRNA) or pcDNA3.1‑PRDX5 expression vector were constructed and transfected into H1299 cells pre‑treated with 100 µM H2O2, the nuclear factor (erythroid‑derived 2)‑like 2 (Nrf2) signaling pathway was inhibited or activated. All these results suggested that the reactive oxygen species (ROS)‑mediated hypomethylation of PRDX5 enhanced STAT3 binding affinity with the promoter region, and resulted in the promotion of cell migration and invasion, as well as in the activation of the Nrf2 signaling pathway in NSCLC. The demethylation status of the PRDX5 promoter may thus be used as an epigenetic biomarker in NSCLC. STAT3/PRDX5 signaling may also prove to be a potential strategy for the treatment of this type of cancer.
脱氧核糖核酸（DNA）的表观遗传修饰与 CpG 岛的特定序列有关，并在肺癌的进展中发挥作用。在本研究中，发现过氧化物酶 5（PRDX5）在非小细胞肺癌（NSCLC）组织中高表达；然而，其在 NSCLC 中的具体调控机制和功能仍不清楚。因此，本研究探讨了 PRDX5 在 NSCLC 氧化应激（OS）条件下的调控机制。结果显示，121 例 NSCLC 患者中有 79 例 PRDX5 启动子区域出现去甲基化，与肿瘤、淋巴结和转移（TNM）分期有关（P=0.027）。PRDX5 信使核糖核酸（mRNA）表达与启动子区域的去甲基化状态呈正相关。亚硫酸氢盐测序聚合酶链反应（BSP）的结果显示，在 0 µM H2O2 处理的 H1299 细胞中，去甲基化频率较低，但在 100 µM H2O2 处理后达到最大去甲基化。通过染色质免疫沉淀（ChIP）和荧光素酶检测实验，证实了 STAT3 与 PRDX5 启动子区域转录结合位点的有效结合（2 个确认的结合位点：位点 1，-444 至-434 bp；和位点 4，-1,417 至-1,407 bp）。STAT3 敲低显著降低了 PRDX5 的蛋白表达水平，而过表达 STAT3 则显著增加了 PRDX5 的蛋白水平。当 OS 条件下肺癌细胞中过表达 PRDX5 时，上皮-间充质转化（EMT）标志物 E-钙黏蛋白和波形蛋白的水平分别显著降低和升高。相比之下，PRDX5 敲低导致 E-钙黏蛋白的表达水平显著增加，波形蛋白的表达水平显著降低。最终，当构建并转染 H1299 细胞 PRDX5-小干扰 RNA（siRNA）或 pcDNA3.1-PRDX5 表达载体，并预先用 100 µM H2O2 处理时，核因子（红细胞衍生 2）样 2（Nrf2）信号通路被抑制或激活。所有这些结果表明，PRDX5 的活性氧（ROS）介导的低甲基化增强了 STAT3 与启动子区域的结合亲和力，从而促进了 NSCLC 细胞的迁移和侵袭，并激活了 Nrf2 信号通路。PRDX5 启动子的去甲基化状态因此可用作 NSCLC 的表观遗传生物标志物。STAT3/PRDX5 信号可能也是治疗这种癌症的一种有潜力的策略。
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