Wu Shun-Long, Li Ya-Jun, Liao Kui, Shi Lei, Zhang Na, Liu Shuang, Hu Yao-Yao, Li Shao-Lin, Wang Ying
Department of Oncology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China.
Zunyi Medical College, Zunyi, Guizhou 563000, P.R. China.
Oncol Rep. 2017 Feb;37(2):793-802. doi: 10.3892/or.2016.5319. Epub 2016 Dec 14.
Accumulating evidence indicates that cancer stem cells (CSCs) are a source of resistance to radiation therapy (RT); however, the mechanism of this resistance remains unclear. 2-Methoxyestradiol (2-ME2) is a metabolic product of estrogen in the body. Recent studies have found that 2-ME2 regulates the activation of transcription factors, including nuclear factor (NF)-κB/hypoxia-inducible factor-1 (HIF-1), thus contributing to tumor cell apoptosis and chemosensitivity. Therefore, 2-ME2 is being studied as a potential anticancer drug. The purpose of this study was to determine the effect and mechanism by which 2-ME2 inhibits nasopharyngeal carcinoma CNE-2 stem-like cell (NPCSC) proliferation and migration and reduces NPCSC radioresistance. This study has important significance for reducing the radioresistance of these cells to improve the cure rate of NPC. First, the NPCSCs were collected in a serum-free culture system and then identified by relevant experiments. The NPCSCs were treated with 2-ME2 (0-8 µM) combined with X-ray exposure and Cell Counting Kit-8 (CCK-8), Transwell assay, colony formation assay, western blot analysis, RT-PCR, flow cytometry and RNA interference technology were used to explore the effect and mechanism of 2-ME2 on NPCSCs. The results showed that the microspheres collected in the serum‑free culture system possessed CSC traits and radioresistance. 2-ME2 obviously inhibited NPCSC growth and migration and reduced NPCSC radioresistance. 2-ME2 decreased NF-κB p65 and HIF-1α protein expression, downregulated NF-κB p65 nuclear localization, and reversed epithelial-mesenchymal transition (EMT). NF-κB p65 knockdown reduced HIF-1α expression, reversed EMT, and enhanced the suppressive effect of 2-ME2 on NPCSCs. Collectively, these data indicate that 2-ME2 inhibits NPCSC proliferation and migration and reduces the radioresistance of NPCSCs via NF-κB/HIF-1 signaling pathway inactivation and EMT reversal.
越来越多的证据表明，癌症干细胞（CSCs）是放疗（RT）耐药性的一个来源；然而，这种耐药性的机制仍不清楚。2-甲氧基雌二醇（2-ME2）是体内雌激素的一种代谢产物。最近的研究发现，2-ME2可调节包括核因子（NF）-κB/缺氧诱导因子-1（HIF-1）在内的转录因子的激活，从而促进肿瘤细胞凋亡和化疗敏感性。因此，2-ME2正在作为一种潜在的抗癌药物进行研究。本研究的目的是确定2-ME2抑制鼻咽癌CNE-2干细胞样细胞（NPCSC）增殖和迁移并降低NPCSC放射抗性的作用及机制。本研究对于降低这些细胞的放射抗性以提高鼻咽癌的治愈率具有重要意义。首先，在无血清培养系统中收集NPCSCs，然后通过相关实验进行鉴定。将NPCSCs用2-ME2（0-8µM）处理并结合X射线照射，采用细胞计数试剂盒-8（CCK-8）、Transwell实验、集落形成实验、蛋白质免疫印迹分析、逆转录-聚合酶链反应（RT-PCR）、流式细胞术和RNA干扰技术来探究2-ME2对NPCSCs的作用及机制。结果显示，在无血清培养系统中收集的微球具有CSC特性和放射抗性。2-ME2明显抑制NPCSC生长和迁移，并降低NPCSC放射抗性。2-ME2降低NF-κB p65和HIF-1α蛋白表达，下调NF-κB p65核定位，并逆转上皮-间质转化（EMT）。NF-κB p65基因敲低降低HIF-1α表达，逆转EMT，并增强2-ME2对NPCSCs的抑制作用。总体而言，这些数据表明，2-ME2通过NF-κB/HIF-1信号通路失活和EMT逆转来抑制NPCSC增殖和迁移，并降低NPCSCs的放射抗性。
