Department of Diagnostic Imaging and Interventional Oncology, Graduate School of Medicine, Juntendo University, Tokyo 113‑8421, Japan.
Division of Medical AI Research and Development, National Cancer Center Research Institute, Tokyo 104‑0045, Japan.
Int J Oncol. 2022 Jan;60(1). doi: 10.3892/ijo.2021.5294. Epub 2021 Dec 16.
RNA modifications have attracted increasing interest in recent years because they have been frequently implicated in various human diseases, including cancer, highlighting the importance of dynamic post‑transcriptional modifications. Methyltransferase‑like 6 (METTL6) is a member of the RNA methyltransferase family that has been identified in many cancers; however, little is known about its specific role or mechanism of action. In the present study, we aimed to study the expression levels and functional role of METTL6 in hepatocellular carcinoma (HCC), and further investigate the relevant pathways. To this end, we systematically conducted bioinformatics analysis of METTL6 in HCC using gene expression data and clinical information from a publicly available dataset. The mRNA expression levels of were significantly upregulated in HCC tumor tissues compared to that in adjacent non‑tumor tissues and strongly associated with poorer survival outcomes in patients with HCC. CRISPR/Cas9‑mediated knockout of METTL6 in HCC cell lines remarkably inhibited colony formation, cell proliferation, cell migration, cell invasion and cell attachment ability. RNA sequencing analysis demonstrated that knockout of METTL6 significantly suppressed the expression of cell adhesion‑related genes. However, chromatin immunoprecipitation sequencing results revealed no significant differences in enhancer activities between cells, which suggests that METTL6 may regulate genes of interest post‑transcriptionally. In addition, it was demonstrated for the first time that METTL6 was localized in the cytosol as detected by immunofluorescence analysis, which indicates the plausible location of RNA modification mediated by METTL6. Our findings provide further insight into the function of RNA modifications in cancer and suggest a possible role of METTL6 as a therapeutic target in HCC.
RNA 修饰近年来引起了越来越多的关注，因为它们经常与各种人类疾病（包括癌症）有关，这突显了动态转录后修饰的重要性。甲基转移酶样 6（METTL6）是 RNA 甲基转移酶家族的成员，已在许多癌症中被鉴定出来；然而，其具体作用或作用机制知之甚少。在本研究中，我们旨在研究 METTL6 在肝细胞癌（HCC）中的表达水平和功能作用，并进一步研究相关途径。为此，我们使用公开数据集的基因表达数据和临床信息，系统地进行了 HCC 中 METTL6 的生物信息学分析。与相邻非肿瘤组织相比，METTL6 的 mRNA 表达水平在 HCC 肿瘤组织中显著上调，并且与 HCC 患者的生存结局较差密切相关。CRISPR/Cas9 介导的 METTL6 在 HCC 细胞系中的敲除显著抑制集落形成、细胞增殖、细胞迁移、细胞侵袭和细胞黏附能力。RNA 测序分析表明，METTL6 的敲除显著抑制了细胞黏附相关基因的表达。然而，染色质免疫沉淀测序结果表明细胞之间的增强子活性没有显著差异，这表明 METTL6 可能在后转录水平调节感兴趣的基因。此外，首次通过免疫荧光分析证明 METTL6 定位于细胞质中，这表明 METTL6 介导的 RNA 修饰的可能位置。我们的研究结果进一步深入了解了 RNA 修饰在癌症中的功能，并表明 METTL6 可能作为 HCC 的治疗靶点发挥作用。
