Tianjin Institute of Urology, the Second Hospital of Tianjin Medical University, Tianjin, 300211, China.
Bone and Soft Tissue Department, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou, 450000, China.
J Exp Clin Cancer Res. 2023 Aug 21;42(1):215. doi: 10.1186/s13046-023-02777-z.
N7-methylguanosine (m7G) modification is, a more common epigenetic modification in addition to m6A modification, mainly found in mRNA capsids, mRNA interiors, transfer RNA (tRNA), pri-miRNA, and ribosomal RNA (rRNA). It has been found that m7G modifications play an important role in mRNA transcription, tRNA stability, rRNA processing maturation, and miRNA biosynthesis. However, the role of m7G modifications within mRNA and its "writer" methyltransferase 1(METTL1) in tumors, particularly prostate cancer (PCa), has not been revealed.
The differential expression level of METTL1 between hormone-sensitive prostate cancer (HSPC) and castrate-resistant prostate cancer (CRPC) was evaluated via RNA-seq and in vitro experiments. The effects of METTL1 on CRPC progression were investigated through in vitro and in vivo assays. The upstream molecular mechanism of METTL1 expression upregulation and the downstream mechanism of its action were explored via Chromatin Immunoprecipitation quantitative reverse transcription polymerase chain reaction (CHIP-qPCR), Co-immunoprecipitation (Co-IP), luciferase reporter assay, transcriptome-sequencing, m7G AlkAniline-Seq, and mRNA degradation experiments, etc. RESULTS AND CONCLUSION: Here, we found that METTL1 was elevated in CRPC and that patients with METTL1 elevation tended to have a poor prognosis. Functionally, the knockdown of METTL1 in CRPC cells significantly limited cell proliferation and invasive capacity. Mechanistically, we unveiled that P300 can form a complex with SP1 and bind to the promoter region of the METTL1 gene via SP1, thereby mediating METTL1 transcriptional upregulation in CRPC. Subsequently, our findings indicated that METTL1 leads to enhanced mRNA stability of CDK14 by adding m7G modifications inside its mRNA, ultimately promoting CRPC progression.
N7-甲基鸟嘌呤（m7G）修饰是一种除 m6A 修饰外更为常见的表观遗传修饰，主要存在于 mRNA 衣壳、mRNA 内部、转移 RNA（tRNA）、pri-miRNA 和核糖体 RNA（rRNA）中。现已发现，m7G 修饰在 mRNA 转录、tRNA 稳定性、rRNA 加工成熟和 miRNA 生物合成中发挥重要作用。然而，mRNA 内的 m7G 修饰及其“书写者”甲基转移酶 1（METTL1）在肿瘤，特别是前列腺癌（PCa）中的作用尚未被揭示。
通过 RNA-seq 和体外实验评估 METTL1 在激素敏感型前列腺癌（HSPC）和去势抵抗性前列腺癌（CRPC）之间的差异表达水平。通过体外和体内实验研究 METTL1 对 CRPC 进展的影响。通过染色质免疫沉淀定量逆转录聚合酶链反应（CHIP-qPCR）、免疫共沉淀（Co-IP）、荧光素酶报告基因测定、转录组测序、m7G AlkAniline-Seq 和 mRNA 降解实验等方法探索 METTL1 表达上调的上游分子机制及其作用的下游机制。
结果表明，METTL1 在 CRPC 中上调，METTL1 升高的患者预后较差。功能上，CRPC 细胞中 METTL1 的敲低显著限制了细胞的增殖和侵袭能力。在机制上，揭示了 P300 可以通过 SP1 与 SP1 形成复合物，并通过 SP1 结合到 METTL1 基因的启动子区域，从而介导 CRPC 中 METTL1 的转录上调。随后，研究结果表明，METTL1 通过在其 mRNA 内添加 m7G 修饰，导致 CDK14 的 mRNA 稳定性增强，最终促进 CRPC 的进展。
