N6‐methyladenosine (m6A) RNA methylation, one of the common RNA modifications, has been determined to execute crucial functions in tumorigenesis and cancer development. The m6A “writers” including methyltransferase like 3 (METTL3), METTL14, and Wilms tumor 1‐associated protein (WTAP) contribute to the m6A modification process initiation. However, the coordination of m6A methyltransferase complex is not fully understood in endometrioid epithelial ovarian cancer (EEOC). In this study, mRNA and protein levels of METTL3, METTL14, and WTAP were detected in 33 EEOC cases using quantitative polymerase chain reaction (qPCR), immunohistochemistry, and western blot analysis. The overall m6A methylation was detected by dot plot. The METTL3 expression and overall m6A level were elevated in EEOC tissues, while the expressions of METTL14 and WTAP have no significant difference in EEOC compared to the adjacent tissues. The expression of METTL3 was an independent factor that correlated with poor malignancy and survival of EEOC patients. Moreover, METTL3 knockdown in TOV‐112D and CRL‐11731D cells weakened the capability of cell proliferation and migration, and promoted cell apoptosis compared to negative control and cells with WTAP or METTL14 knockdown using CCK‐8 assay, transwell assay, wound healing assay, and TUNEL assay. Furthermore, METTL3 knockdown also reduced m6A enrichment of the genes associated with ovarian cancer including EIF3C, AXL, CSF‐1, FZD10 in TOV‐112D, and CRL‐11731D cells by RIP‐qPCR assay. Taken together, the high expressed METTL3 indicated poor malignancy and survival of EEOC via modulating the aberrant m6A RNA methylation. METTL3‐mediated m6A modification, independent of WTAP and METTL14, was considered as a novel mechanism underlying m6A modulation and a potential therapeutic target of EEOC.

中文翻译：

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METTL3 独立于 METTl14 和 WTAP 调节子宫内膜样上皮性卵巢癌中的 m6A。

N6-甲基腺苷 (m6A) RNA 甲基化是常见的 RNA 修饰之一，已被确定在肿瘤发生和癌症发展中发挥关键作用。包括甲基转移酶 3 (METTL3)、METTL14 和 Wilms 肿瘤 1 相关蛋白 (WTAP) 在内的 m6A“编写者”有助于 m6A 修饰过程的启动。然而，m6A 甲基转移酶复合物在子宫内膜样上皮性卵巢癌 (EEOC) 中的协调尚未完全了解。在这项研究中，使用定量聚合酶链反应 (qPCR)、免疫组织化学和蛋白质印迹分析在 33 例 EEOC 病例中检测了 METTL3、METTL14 和 WTAP 的 mRNA 和蛋白质水平。通过点图检测整体 m6A 甲基化。EEOC 组织中 METTL3 表达和整体 m6A 水平升高，而 METTL14 和 WTAP 的表达在 EEOC 中与邻近组织相比没有显着差异。METTL3 的表达是与 EEOC 患者恶性程度和生存率相关的独立因素。此外，与阴性对照和 WTAP 或 METTL14 敲低的细胞相比，TOV-112D 和 CRL-11731D 细胞中的 METTL3 敲低减弱了细胞增殖和迁移的能力，并促进了细胞凋亡。和 TUNEL 检测。此外，通过 RIP-qPCR 测定，METTL3 敲低还减少了与卵巢癌相关的基因的 m6A 富集，包括 TOV-112D 和 CRL-11731D 细胞中的 EIF3C、AXL、CSF-1、FZD10。总之，高表达的 METTL3 通过调节异常的 m6A RNA 甲基化表明 EEOC 的恶性程度和存活率较差。