Jin Bicheng, Jin Dongfang, Zhuo Zhaozhen, Zhang Bo, Chen Kun
Department of Surgery, Guizhou Electric Power Staff Hospital, Guiyang, Guizhou Province, People's Republic of China.
Department of Clinical Laboratory, Jinhua People's Hospital, Jinhua, Zhejiang Province, People's Republic of China.
Onco Targets Ther. 2020 Nov 17;13:11807-11818. doi: 10.2147/OTT.S274451. eCollection 2020.
Osteosarcoma (OS) is one of the most common malignant bone tumors with a poor overall prognosis. MiR-1224-5p plays an important role in cancer, but its function and mechanism in OS have not been studied.
The expression of miR-1224-5p and PLK1 was detected by qRT-PCR in OS cells, adjacent tissues, and cell lines. Dual-luciferase reporter gene assay was used to verify the interaction between miR-1224-5p and PLK1. The expression of miR-1224-5p and PLK1 was intervened by transfection with miR-1224-5p mimic, NC mimic, pc-NC and PLK1, respectively. MTT, colony formation assay, Transwell and flow cytometry were used to observe the cell proliferation, invasion and apoptosis. Western blot was used to detect the expression levels of PLK1, PI3K/AKT/mTOR signaling pathway-related proteins, autophagy-related proteins, and epithelial-mesenchymal transition (EMT)-related proteins in the cells.
We found that miR-1224-5p was down-regulated and PLK1 expression was up-regulated in OS tissues and cells. On the other hand, it is further confirmed that PLK1 was a target gene of miR-1224-5p. Overexpression of miR-1224-5p inhibited the proliferation, invasion while promoted the apoptosis of OS cells, whereas overexpression of PLK1 promoted the proliferation, invasion and inhibited the apoptosis of OS cells. In the miR-1224-5p group (overexpression of miR-1224-5p), PI3K, AKT, and mTOR protein phosphorylation levels were significantly reduced, while autophagic activity was significantly activated, and the degree of EMT was significantly reduced. But the results in the PLK1 group (overexpression of PLK1) were the opposite. In addition, overexpression of miR-1224-5p reversed the effect of PLK1 upregulation on OS cells.
MiR-1224-5p targets PLK1 to inhibit PI3K/AKT/mTOR signaling pathway, thus mediating the proliferation, invasion, apoptosis, autophagy and EMT in OS cells.
骨肉瘤（OS）是最常见的恶性骨肿瘤之一，总体预后较差。MiR-1224-5p在癌症中发挥重要作用，但其在骨肉瘤中的功能和机制尚未得到研究。
采用qRT-PCR检测骨肉瘤细胞、癌旁组织及细胞系中miR-1224-5p和PLK1的表达。双荧光素酶报告基因检测法验证miR-1224-5p与PLK1之间的相互作用。分别转染miR-1224-5p模拟物、NC模拟物、pc-NC和PLK1干预miR-1224-5p和PLK1的表达。采用MTT法、集落形成实验、Transwell实验和流式细胞术观察细胞增殖、侵袭和凋亡情况。采用蛋白质免疫印迹法检测细胞中PLK1、PI3K/AKT/mTOR信号通路相关蛋白、自噬相关蛋白和上皮-间质转化（EMT）相关蛋白的表达水平。
我们发现miR-1224-5p在骨肉瘤组织和细胞中表达下调，而PLK1表达上调。另一方面，进一步证实PLK1是miR-1224-5p的靶基因。过表达miR-1224-5p可抑制骨肉瘤细胞的增殖、侵袭，同时促进其凋亡，而过表达PLK1则促进骨肉瘤细胞的增殖、侵袭并抑制其凋亡。在miR-1224-5p组（miR-1224-5p过表达）中，PI3K、AKT和mTOR蛋白磷酸化水平显著降低，而自噬活性显著激活，EMT程度显著降低。但PLK1组（PLK1过表达）的结果则相反。此外，过表达miR-1224-5p可逆转PLK1上调对骨肉瘤细胞的影响。
MiR-1224-5p靶向PLK1以抑制PI3K/AKT/mTOR信号通路，从而介导骨肉瘤细胞的增殖、侵袭、凋亡、自噬和EMT。
