Liang Shumei, Guan Hongwei, Lin Xiaoyan, Li Na, Geng Feng, Li Juan
Department of Obstetrics and Gynecology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China.
Department of Obstetrics and Gynecology, Weihai Huancui Maternal and Child Care Family Planning Service Centre, Weihai, Shandong 264200, P.R. China.
Oncol Lett. 2020 Apr;19(4):3197-3204. doi: 10.3892/ol.2020.11425. Epub 2020 Mar 3.
Methyltransferase-like 3 (METTL3) has been identified as a methyltransferase responsible for N6-methyla-denosine (m6A) modification of mRNA. METTL3 functions in tumorigenesis and tumor development by promoting the translation of oncoproteins; however, the role of METTL3 in ovarian cancer has not been extensively studied. The present study performed immunohistochemistry to detect METTL3 expression levels in 52 samples of ovarian cancer tissue paired with corresponding paracancerous tissue. RNA interference was conducted to downregulate the expression levels of METTL3 in the SKOV3 and OVCAR3 ovarian cancer cell lines. Reverse transcription-quantitative PCR and western blot analysis demonstrated the effects of METTL3 knockdown on mRNA and protein levels, respectively. CCK-8, colony formation, apoptosis and Transwell assays were also performed. The results demonstrated that METTL3 exhibited significantly higher expression levels in ovarian cancer tissues compared with corresponding paracancerous tissue. High METTL3 expression levels were associated with large tumors, lymph node metastasis and high pathological grade. Cell proliferation analysis revealed that METTL3 knockdown reduced the proliferation and clonogenic ability of SKOV3 and OVCAR3 cells. Apoptotic rates were increased in METTL3-silenced ovarian cancer cells, which may have been mediated by the activation of the mitochondrial apoptosis pathway, and METTL3 knockdown reduced cell invasion. METTL3 knockdown downregulated the phosphorylation levels of AKT and the expression of the downstream effector Cyclin D1. These results suggested that METTL3 may serve an oncogenic function in the progression of human ovarian cancer cells partially through the AKT signaling pathway, indicating that METTL3 may be a potentially novel therapeutic target for the treatment of ovarian cancer.
甲基转移酶样3（METTL3）已被鉴定为一种负责mRNA的N6-甲基腺苷（m6A）修饰的甲基转移酶。METTL3通过促进癌蛋白的翻译在肿瘤发生和肿瘤发展中发挥作用；然而，METTL3在卵巢癌中的作用尚未得到广泛研究。本研究进行免疫组织化学检测52例卵巢癌组织及其相应癌旁组织中METTL3的表达水平。进行RNA干扰以下调SKOV3和OVCAR3卵巢癌细胞系中METTL3的表达水平。逆转录定量PCR和蛋白质印迹分析分别证明了敲低METTL3对mRNA和蛋白质水平的影响。还进行了CCK-8、集落形成、凋亡和Transwell实验。结果表明，与相应癌旁组织相比，METTL3在卵巢癌组织中的表达水平显著更高。METTL3高表达水平与肿瘤体积大、淋巴结转移和高病理分级相关。细胞增殖分析显示，敲低METTL3可降低SKOV3和OVCAR3细胞的增殖和克隆形成能力。METTL3沉默的卵巢癌细胞凋亡率增加，这可能是由线粒体凋亡途径的激活介导的，并且敲低METTL3可降低细胞侵袭。敲低METTL3可下调AKT的磷酸化水平和下游效应分子细胞周期蛋白D1的表达。这些结果表明，METTL3可能在人卵巢癌细胞进展中发挥致癌作用，部分是通过AKT信号通路，这表明METTL3可能是治疗卵巢癌的潜在新治疗靶点。
