Yong Min, Hu Jianguo, Zhu Hongtao, Jiang Xinwei, Gan Xiaolin, Hu Lina
Department of Obstetrics and Gynecology, Second Affiliated Hospital, Chongqing Medical University Linjiang Road, No. 76, Chongqing 400010, China.
Joint International Research Lab for Reproduction and Development, Ministry of Education China.
Am J Cancer Res. 2020 Nov 1;10(11):3737-3751. eCollection 2020.
Circular RNAs, a special class of non-coding RNA with closed circular structure, have been increasingly proven to be involved in the progression of various tumors. However, the biological functions of circular RNAs in epithelial ovarian cancer (EOC) tissues remain a mystery. In this study, we detected the function of circEEF2 (has-circ-0048559) in EOC tissues. Firstly, the basic characteristics including closed circular structure and spliced mature sequence length of circEEF2 were confirmed. The location and expression in EOC tissues was detected by fluorescence in situ hybridization (FISH). The regulatory effect of circEEF2 on autophagy, proliferation, and invasion were investigated in SKOV3 and A2780 cells. The relationship between circEEF2 and mir-6881-3p was confirmed using dual-luciferase reporter gene assay. The binding of circEEF2 with ANXA2 was confirmed using RNA-pulldown assay and MALDI-TOF-MS. We found that the expression level of circEEF2 was higher in EOC tissue than in normal tissue. CircEEF2 promoted autophagy, proliferation, and invasion. CircEEF2-regulated EOC proliferation and invasion are closely related to the occurrence of autophagy. Mechanistically, circEEF2 harbor miR-6881-3p to upregulate the latter's targets ATG5 and ATG7. Moreover, circEEF2 could directly bind with ANXA2 to inhibit the expression of p-mTOR. In conclusion, findings of the current study illustrate that circEEF2 promoted autophagy, proliferation, and invasion of EOC by interacting with miR-6881-3p and ANXA2.
环状RNA是一类具有封闭环状结构的特殊非编码RNA，越来越多的证据表明其参与了多种肿瘤的进展。然而，环状RNA在上皮性卵巢癌（EOC）组织中的生物学功能仍是个谜。在本研究中，我们检测了环状EEF2（has-circ-0048559）在EOC组织中的功能。首先，证实了环状EEF2的基本特征，包括封闭环状结构和剪接成熟序列长度。通过荧光原位杂交（FISH）检测其在EOC组织中的定位和表达。在SKOV3和A2780细胞中研究了环状EEF2对自噬、增殖和侵袭的调节作用。使用双荧光素酶报告基因测定法证实了环状EEF2与mir-6881-3p之间的关系。使用RNA下拉测定法和基质辅助激光解吸电离飞行时间质谱（MALDI-TOF-MS）证实了环状EEF2与膜联蛋白A2（ANXA2）的结合。我们发现，环状EEF2在EOC组织中的表达水平高于正常组织。环状EEF2促进自噬、增殖和侵袭。环状EEF2调节的EOC增殖和侵袭与自噬的发生密切相关。机制上，环状EEF2携带miR-6881-3p以上调后者的靶标ATG5和ATG7。此外，环状EEF2可直接与ANXA2结合以抑制p-mTOR的表达。总之，本研究结果表明，环状EEF2通过与miR-6881-3p和ANXA2相互作用促进了EOC的自噬、增殖和侵袭。
