Department of Precision Medicine Center, Tianjin Medical University General Hospital, Tianjin, China.
Eur Rev Med Pharmacol Sci. 2020 Mar;24(5):2585-2600. doi: 10.26355/eurrev_202003_20528.
Glioma is a primary intracranial tumor with an unfavorable prognosis. Evolving evidence indicates that circular RNA Tau tubulin kinase 2 (circ-TTBK2) is a cancer-associated gene. Therefore, this study was to explore the potential role of circ-TTBK2.
Levels of circ-TTBK2, microRNA (miR)-761, and integrin subunit beta 8 (ITGB8) were determined by adopting quantitative real-time polymerase chain reaction (qRT-PCR) or Western blot. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to detect cell viability, and the invaded cells were distinguished utilizing transwell assay. Iron and lipid reactive oxygen species (ROS) assays were implemented to examine the iron (total iron and ferrous iron) and lipid-based ROS in glioma cells, respectively. Besides, dual-luciferase reporter assay was administrated to illustrate the interaction between miR-761 and circ-TTBK2 or ITGB8. The role of circ-TTBK2 was identified via xenograft tumor model.
Levels of circ-TTBK2 and ITGB8 were upregulated, whereas miR-761 level was low-expressed in glioma tissues and cells. Circ-TTBK2 was a sponge of miR-761 to modulate ITGB8. Additionally, circ-TTBK2 knockdown or miR-761 increase could retard cell proliferation, invasion, and promote ferroptosis in glioma cells. Interestingly, miR-761 inhibitor could abolish the repressive impact of circ-TTBK2 silencing on cell growth in vitro. Also, the influence of miR-761 mimic on cell phenotypes was regained after ITGB8 upregulation. Meanwhile, circ-TTBK2 deficiency caused the decrease of tumor growth.
Circ-TTBK2 regulated cell proliferation, invasion and ferroptosis via targeting ITGB8 by sponging miR-761 in glioma, providing a promising biomarker for the clinical therapy of human glioma.
神经胶质瘤是一种原发性颅内肿瘤，预后不良。不断发展的证据表明，环状 RNA 微管相关蛋白 Tau 激酶 2（circ-TTBK2）是一种与癌症相关的基因。因此，本研究旨在探讨 circ-TTBK2 的潜在作用。
采用实时定量聚合酶链反应（qRT-PCR）或 Western blot 检测 circ-TTBK2、microRNA（miR）-761 和整合素亚基β 8（ITGB8）的水平。采用 3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四唑溴盐（MTT）法检测细胞活力，采用 Transwell 法检测侵袭细胞。分别采用铁和脂质活性氧（ROS）测定法检测胶质瘤细胞中的铁（总铁和亚铁）和脂质 ROS。此外，还进行了双荧光素酶报告基因实验以说明 miR-761 与 circ-TTBK2 或 ITGB8 之间的相互作用。通过异种移植肿瘤模型确定 circ-TTBK2 的作用。
circ-TTBK2 和 ITGB8 的水平上调，而 miR-761 的水平在神经胶质瘤组织和细胞中低表达。circ-TTBK2 是 miR-761 的海绵体，可调节 ITGB8。此外，circ-TTBK2 敲低或 miR-761 增加可抑制胶质瘤细胞的增殖、侵袭，并促进铁死亡。有趣的是，miR-761 抑制剂可消除 circ-TTBK2 沉默对体外细胞生长的抑制作用。此外，上调 ITGB8 后可恢复 miR-761 模拟物对细胞表型的影响。同时，circ-TTBK2 缺乏导致肿瘤生长减少。
circ-TTBK2 通过靶向 ITGB8 调节细胞增殖、侵袭和铁死亡，为人类神经胶质瘤的临床治疗提供了有前途的生物标志物。
