环状 RNA 多效蛋白通过调节 microRNA-122/SRY 盒转录因子 6 轴促进胶质瘤发生。
Circular RNA Pleiotrophin promotes carcinogenesis in glioma via regulation of microRNA-122/SRY-box transcription factor 6 axis.
机构信息
Department of Neurosurgery, The Second Affiliated Hospital of Soochow University, Suzhou.
Department of Neurosurgery, Yancheng City No. 1 People's Hospital, Yancheng.
出版信息
Eur J Cancer Prev. 2020 Mar;29(2):165-173. doi: 10.1097/CEJ.0000000000000535.
BACKGROUND
Circular RNAs (circRNAs) are recently identified as gene regulators in mammals and play important roles in carcinogenesis of cancer. For example, circRNA_PTN has been recognized as a biomarker of human cancer and is overexpressed in glioma. The molecular function of circRNA_PTN and its downstream targets in glioma, however, remains elusive.
METHODS
Quantitative polymerase chain reaction analysis was used to measure the expression of circular RNA pleiotrophin (circ_PTN) and miR-122. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, propidium iodide and Annexin-V/propidium iodide assay were performed to determine cell proliferation and apoptosis of glioma cells. Circular RNA Interactome and TargetScan were used to predict the potential microRNA targeting of circ_PTN and the potential targets of miR-122, respectively. Luciferase activity assay was used to validate these interactions. Downstream molecular mechanisms, including SRY-box transcription factor 6 (SOX6), extracellular regulated protein kinases (ERK), Cyclin D1, B-cell lymphoma-2 (BCL-2) and BCL2 associated X, apoptosis regulator (BAX), were determined by western blot.
RESULTS
Circ_PTN was overexpressed in glioma cells, and its knockdown induced cell proliferation inhibition, cell cycle arrest and apoptosis in glioma cells. The target microRNA of circ_PTN was predicted to be miR-122, the expression of which was negatively correlated with circ_PTN in glioma cells. Moreover, SOX6 was predicted as a potential target of miR-122, and miR-122 overexpression decreased SOX6 expression. MiR-122 inhibitor reversed the tumor-suppressing effects of circ_PTN knockdown, while overexpression of SOX6 impaired the miR-122 overexpression-induced cell growth inhibition and apoptosis. In addition, mitogen activated kinase-like protein (MAPK)/ERK pathway was involved in circ_PTN/miR-122/SOX6 axis.
CONCLUSIONS
Circ_PTN acted as a sponge of miR-122 and upregulated miR-122 target SOX6, thus promoting carcinogenesis of glioma cells.
背景
环状 RNA（circRNAs）最近被鉴定为哺乳动物中的基因调控因子，在癌症的发生中发挥重要作用。例如，环状 RNA_PTN 已被认为是人类癌症的生物标志物，在神经胶质瘤中过度表达。然而，circRNA_PTN 在神经胶质瘤中的分子功能及其下游靶标仍不清楚。
方法
采用实时定量聚合酶链反应分析检测环状 RNA 多效蛋白（circ_PTN）和 miR-122 的表达。采用 3-(4,5-二甲基-2-噻唑基)-2,5-二苯基-2-H-四唑溴盐（MTT）比色法、碘化丙啶（PI）和 Annexin-V/PI 检测试剂盒分别检测神经胶质瘤细胞的增殖和凋亡。采用环状 RNA 相互作用组和 TargetScan 分别预测 circ_PTN 的潜在 microRNA 靶点和 miR-122 的潜在靶点。采用荧光素酶活性检测验证这些相互作用。通过 Western blot 检测下游分子机制，包括性决定区 Y 框转录因子 6（SOX6）、细胞外调节蛋白激酶（ERK）、细胞周期蛋白 D1（Cyclin D1）、B 细胞淋巴瘤-2（BCL-2）和 BCL2 相关 X，凋亡调节剂（BAX）。
结果
circ_PTN 在神经胶质瘤细胞中过度表达，其敲低可诱导神经胶质瘤细胞增殖抑制、细胞周期阻滞和凋亡。circ_PTN 的靶 microRNA 被预测为 miR-122，其表达与神经胶质瘤细胞中的 circ_PTN 呈负相关。此外，SOX6 被预测为 miR-122 的潜在靶标，miR-122 的过表达可降低 SOX6 的表达。miR-122 抑制剂逆转了 circ_PTN 敲低的肿瘤抑制作用，而过表达 SOX6 则损害了 miR-122 过表达诱导的细胞生长抑制和凋亡。此外，丝裂原活化蛋白激酶样蛋白（MAPK/ERK）通路参与了 circ_PTN/miR-122/SOX6 轴。
结论
circ_PTN 作为 miR-122 的海绵，上调 miR-122 的靶标 SOX6，从而促进神经胶质瘤细胞的致癌作用。
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