Abstract:
Background: Upper tract urothelial carcinoma (UTUC) is a distinct malignancy arising from the renal pelvis or ureter. Globally, UTUC represents 5–10% of urothelial carcinomas, but in Taiwan its incidence reaches up to 30%, the highest reported worldwide. This epidemiological uniqueness highlights the need to define UTUC-specific molecular mechanisms that can guide improved diagnostics and therapeutic strategies. N6-methyladenosine (m6A) is the most common and abundant post-transcriptional modification found in eukaryotic RNAs and is known to regulate RNA splicing, processing, degradation, storage, stability, transport, localization, and translation. m6A modification of RNA has been implicated in various diseases, including cancer, and has been shown to influence critical cancer cell functions, such as proliferation, invasion, metastasis, and drug resistance. Although METTL3, a major m6A writer with methyltransferase activity, has been extensively studied in bladder cancer, its role in UTUC remains largely unknown. This study aims to investigate the role of METTL3-mediated m6A modification in UTUC.
Methods: Paired UTUC tumor and adjacent normal tissues were analyzed using RNA-seq and m6A-methylated RNA immunoprecipitation (MeRIP) microarray. Differentially expressed and differentially methylated mRNAs were identified and compared with the public dataset GSE159824 from the GEO database to filter m6A-regulated candidates. Functional studies were conducted to confirm the direct involvement of candidate mRNAs and their encoded proteins in UTUC progression.
Results: A total of 3579 differentially expressed mRNAs and 366 differentially methylated mRNAs were detected. Cross-comparison with GSE159824 identified 73 m6A-regulated mRNAs, including multiple drivers of tumor growth and the cell cycle, such as CCND1, CCNB1, CDK1, and CDC25C. Functional studies in urothelial carcinoma cell lines showed that METTL3 overexpression enhances proliferation, colony formation, migration, and invasion, whereas METTL3 knockdown reverses these oncogenic behaviors. Several tumor growth–related mRNAs regulated by the METTL3/m6A axis were also identified.
Conclusions: This study provides new insights into UTUC-specific epitranscriptomic regulation and highlights METTL3 as a potential therapeutic target for advancing precision medicine in UTUC.
