NOP2-mediated 5-methylcytosine modification of APOL1 messenger RNA activates PI3K-Akt and facilitates clear cell renal cell carcinoma progression

Background: By regulating the functions of multiple RNAs, 5-methylcytosine (m⁵C) RNA methylation, particularly mediated by NOP2, is involved in tumorigenesis and developments. However, the specific functions and potential mechanisms of m⁵C, especially involving NOP2, in clear-cell renal cell carcinoma (ccRCC), remain unclear./nMethods: NOP2 expression in cell lines and patient tissues was detected using western blotting, quantitative real-time polymerase chain reaction (RT-qPCR), and immunohistochemistry. The biological effects of NOP2 on ccRCC cells were investigated through a series of in vitro and in vivo experiments. To explore the potential regulatory mechanisms by which NOP2 affects ccRCC progression, m⁵C bisulfite sequencing, RNA-sequencing, RNA immunoprecipitation and methylated RNA immunoprecipitation (RIP/MeRIP) RT-qPCR assay, luciferase reporter assay, RNA stability assay, and bioinformatic analysis were performed./nResults: NOP2 expression was significantly upregulated in ccRCC tissues and was associated with poor prognosis. Moreover, loss-of-function and gain-of-function assays demonstrated that NOP2 altered ccRCC cell proliferation, migration, and invasion. Mechanistically, NOP2 stimulated m⁵C modification of apolipoprotein L1 (APOL1) mRNA, and m⁵C reader YBX1 stabilized APOL1 mRNA through recognizing and binding to m⁵C site in the 3′-untranslated regions. Silencing APOL1 expression inhibited ccRCC cell proliferation in vitro and tumor formation in vivo. Furthermore, NOP2/APOL1 affected ccRCC progression via the PI3K-Akt signaling pathway./nConclusion: NOP2 functions as an oncogene in ccRCC by promoting tumor progression through the m⁵C-dependent stabilization of APOL1, which in turn regulates the PI3K-Akt signaling pathway, suggesting a potential therapeutic target for ccRCC.