Department of Vascular Surgery, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China.
Int J Mol Med. 2018 Sep;42(3):1367-1378. doi: 10.3892/ijmm.2018.3746. Epub 2018 Jun 27.
Abdominal aortic aneurysm (AAA) is a common disease, which is characterized by the apoptosis of vascular smooth muscle cells (VSMCs). In previous years, microRNAs (miRNAs) have been associated with AAA and functionally implicated in the pathogenesis of this disease. However, the role of miRNAs in the apoptosis of VSMCs remains to be fully elucidated. The present study aimed to elucidate the role and mechanism of miRNAs in protecting against hydrogen peroxide (H2O2)‑induced apoptosis in VSMCs. The expression of miRNAs in peripheral blood from patients diagnosed with AAA was analyzed using a microarray and reverse transcription polymerase chain reaction. A VSMC injury model induced by H2O2 was used to determine the potential role of miR‑26a against cell injury. Cell viability, cell apoptosis and reactive oxygen species (ROS) generation were determined by a CCK8 assay, flow cytometry and a 2',7'‑DCF diacetate assay, respectively. It was observed that miRNA (miR)‑26a (miR‑26a‑1‑5p) was significantly downregulated in peripheral blood samples from patients with AAA. It was revealed that H2O2 treatment dose‑dependently inhibited cell viability, enhanced apoptosis and induced the production of ROS, which indicated the success of the model establishment. It was also observed that miR‑26a was downregulated in the VSMCs following H2O2 stimulation. The upregulation of miR‑26a attenuated H2O2‑induced cell injury, as evidenced by the enhancement of cell viability, and inhibition of the activity of caspase‑3, apoptosis and ROS production. In addition, phosphatase and tensin homolog (PTEN), a well‑known regulator of the AKT/mammalian target of rapamycin (mTOR) pathway, was found to be a direct target of miR‑26a in the VSMCs and this was validated using a luciferase reporter assay. Overexpression of PTEN by pcDNA‑PTEN plasmids markedly eliminated the protective effects of the overexpression of miR‑26a on H2O2‑induced cell injury. Finally, it was found that miR‑26a mediated its anti‑apoptotic action by reactivation of the AKT/mTOR pathway, as demonstrated by the upregulation of phosphorylated (p‑)AKT and p‑mTOR, and the Akt inhibitor API‑2 reversing the protective effects on VSMCs mediated by miR‑26a. These results indicated that miR‑26a protected VSMCs against H2O2‑induced injury through activation of the PTEN/AKT/mTOR pathway, and miR‑26a may be considered as a potential prognostic biomarker and therapeutic target in the treatment of AAA.
腹主动脉瘤（AAA）是一种常见疾病，其特征在于血管平滑肌细胞（VSMC）的凋亡。近年来，microRNAs（miRNAs）与 AAA 相关，并在该疾病的发病机制中具有功能意义。然而，miRNAs 在 VSMC 凋亡中的作用仍有待充分阐明。本研究旨在阐明 miRNAs 在保护 VSMC 免受过氧化氢（H2O2）诱导的凋亡中的作用和机制。使用微阵列和逆转录聚合酶链反应分析诊断为 AAA 的患者外周血中的 miRNA 表达。使用 H2O2 诱导的 VSMC 损伤模型来确定 miR-26a 对细胞损伤的潜在作用。通过 CCK8 测定、流式细胞术和 2'，7'-二氯荧光素二乙酸酯测定分别测定细胞活力、细胞凋亡和活性氧（ROS）的产生。结果观察到，AAA 患者外周血样本中 miRNA（miR）-26a（miR-26a-1-5p）显著下调。结果表明，H2O2 处理剂量依赖性地抑制细胞活力，增强细胞凋亡并诱导 ROS 的产生，这表明模型建立成功。结果还观察到，H2O2 刺激后 VSMCs 中 miR-26a 下调。上调 miR-26a 可减轻 H2O2 诱导的细胞损伤，表现为细胞活力增强，以及 caspase-3 活性、凋亡和 ROS 产生的抑制。此外，发现磷酸酶和张力蛋白同源物（PTEN）是 AKT/哺乳动物雷帕霉素靶蛋白（mTOR）通路的众所周知的调节剂，是 VSMCs 中 miR-26a 的直接靶标，这通过荧光素酶报告基因测定得到验证。pcDNA-PTEN 质粒过表达 PTEN 显著消除了 miR-26a 过表达对 H2O2 诱导的细胞损伤的保护作用。最后，发现 miR-26a 通过重新激活 AKT/mTOR 通路发挥其抗凋亡作用，表现为磷酸化（p-）AKT 和 p-mTOR 的上调，以及 Akt 抑制剂 API-2 逆转 miR-26a 介导的对 VSMCs 的保护作用。这些结果表明，miR-26a 通过激活 PTEN/AKT/mTOR 通路保护 VSMCs 免受 H2O2 诱导的损伤，miR-26a 可能被认为是治疗 AAA 的潜在预后生物标志物和治疗靶点。
