NSUN2-mediated RNA m5C modification modulates uveal melanoma cell proliferation and migration

RNA 5-methylcytosine (m5C) is a widespread post-transcriptional modification involved in diverse biological processes through controlling RNA metabolism. However, its roles in uveal melanoma (UM) remain unknown. Here, we describe the biological roles and regulatory mechanisms of RNA m5C in UM. Initially, we identified significantly elevated global RNA m5C levels in both UM cells and tissue specimens using ELISA assay and dot blot analysis. Meanwhile, NOP2/Sun RNA methyltransferase family member 2 (NSUN2) was upregulated in both types of these samples, whereas NSUN2 knockdown significantly decreased RNA m5C level. Such declines inhibited UM cell migration and suppressed cell proliferation through cell cycle G1 arrest. Furthermore, bioinformatic analyses, m5C-RIP-qPCR, and luciferase assay identified β-Catenin (CTNNB1) as a direct target of NSUN2-mediated m5C modification in UM cells. Additionally, overexpression of miR-124a in UM cells diminished NSUN2 expression levels indicating that it is an upstream regulator of this response. Our study suggests that NSUN2-mediated RNA m5C methylation provides a potential novel target to improve the therapeutic management of UM pathogenesis.

RNA 5-甲基胞嘧啶（m5C）是一类广泛存在的转录后修饰，可通过调控RNA代谢参与多种生物学过程。然而其在葡萄膜黑色素瘤（UM）中的作用仍不明晰。本研究阐明了RNA m5C在UM中的生物学功能及其调控机制。研究伊始，我们通过酶联免疫吸附测定（ELISA）与斑点印迹分析，确认UM细胞与组织标本中整体RNA m5C水平均显著升高。同时，两类样本中NOP2/Sun RNA甲基转移酶家族成员2（NSUN2）均呈现上调表达；而敲低NSUN2可显著降低RNA m5C水平，此类下调可抑制UM细胞迁移，并通过引发细胞周期G1期阻滞抑制细胞增殖。进一步通过生物信息学分析、m5C RNA免疫沉淀定量聚合酶链反应（m5C-RIP-qPCR）与荧光素酶报告基因测定，我们证实β-连环蛋白（CTNNB1）是UM细胞中NSUN2介导的m5C修饰的直接靶标。此外，在UM细胞中过表达miR-124a可降低NSUN2的表达水平，表明miR-124a是该调控通路的上游调控因子。本研究提示，NSUN2介导的RNA m5C甲基化为改善UM发病机制的临床治疗管理提供了潜在的新型靶点。