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

By regulating the functions of multiple RNAs, 5-methylcytosine (mC) RNA methylation, particularly mediated by NOP2, is involved in tumorigenesis and developments. However, the specific functions and potential mechanisms of mC, especially involving NOP2, in clear-cell renal cell carcinoma (ccRCC), remain unclear. 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 and experiments. To explore the potential regulatory mechanisms by which NOP2 affects ccRCC progression, mC 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. 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 mC modification of apolipoprotein L1 (APOL1) mRNA, and mC reader YBX1 stabilized APOL1 mRNA through recognizing and binding to mC site in the 3'-untranslated regions. Silencing APOL1 expression inhibited ccRCC cell proliferation and tumor formation . Furthermore, NOP2/APOL1 affected ccRCC progression via the PI3K-Akt signaling pathway. NOP2 functions as an oncogene in ccRCC by promoting tumor progression through the mC-dependent stabilization of APOL1, which in turn regulates the PI3K-Akt signaling pathway, suggesting a potential therapeutic target for ccRCC.