结肠腺癌（COAD）是消化系统常见的致命性恶性肿瘤，病因复杂。 NSUN 基因家族 (NSUN1-NSUN7) 和 DNMT2 对 RNA 的 5-甲基胞嘧啶 (m5C) 修饰重塑细胞生物学并调节肿瘤发展。然而，这些 m5C 修饰因子在 COAD 中的表达谱、预后意义和功能仍不清楚。通过挖掘多个整合的肿瘤数据库，我们发现相对于正常样本，NSUN1、NSUN2、NSUN5和NSUN6在COAD肿瘤样本中过表达。临床上，NSUN6的高表达与COAD患者的较短生存期（包括无病生存期和总生存期）显着相关。进一步证实 NSUN6 在 COAD 的组织和细胞水平上表达上调，表明 NSUN6 在疾病进展中发挥着关键作用。通过全面的基因富集分析和基于细胞的功能验证，揭示NSUN6促进COAD的细胞周期进程和细胞增殖。从机制上讲，NSUN6 上调 COAD 细胞中致癌 METTL3 的表达并催化其 m5C 修饰。 METTL3的过表达显着缓解了NSUN6缺陷引起的COAD细胞周期抑制。此外，NSUN6 与 COAD 肿瘤中浸润免疫细胞的丰度呈负相关，例如激活的 B 细胞、自然杀伤细胞、效应记忆 CD8 T 细胞和调节性 T 细胞。重要的是，泛癌分析进一步发现 NSUN6 在各种肿瘤中失调且具有异质性。因此，我们的研究结果扩展了 m5C 转移酶在 COAD 中的作用，并表明 NSUN6 是这种恶性肿瘤的潜在生物标志物和靶标。© 2024 Wiley periodicals LLC。

Colon adenocarcinoma (COAD) is a common and fatal malignant tumor of digestive system with complex etiology. 5-Methylcytosine (m5C) modification of RNA by the NSUN gene family (NSUN1-NSUN7) and DNMT2 reshape cell biology and regulate tumor development. However, the expression profile, prognostic significance and function of these m5C modifiers in COAD remain largely unclear. By mining multiple integrated tumor databases, we found that NSUN1, NSUN2, NSUN5, and NSUN6 were overexpressed in COAD tumor samples relative to normal samples. Clinically, high expression of NSUN6 was significantly associated with shorter survival (including both disease-free survival and overall survival) in COAD patients. NSUN6 was further confirmed to be upregulated at both tissue and cellular levels of COAD, suggesting that NSUN6 plays a critical role in disease progression. Through comprehensive gene enrichment analysis and cell-based functional validation, it was revealed that NSUN6 promoted the cell cycle progression and cell proliferation of COAD. Mechanistically, NSUN6 upregulates the expression of oncogenic METTL3 and catalyzes its m5C modification in COAD cells. Overexpression of METTL3 significantly relieved the cell cycle inhibition of COAD caused by NSUN6 deficiency. Furthermore, NSUN6 was negatively associated with the abundance of infiltrating immune cells in COAD tumors, such as activated B cells, natural killer cells, effector memory CD8 T cells, and regulatory T cells. Importantly, pan-cancer analysis further uncovered that NSUN6 was dysregulated and heterogeneous in various tumors. Thus our findings extend the role of m5C transferase in COAD and suggest that NSUN6 is a potential biomarker and target for this malignancy.© 2024 Wiley Periodicals LLC.