A comprehensive investigation of crosstalk between m5C writer NSUN2 and MYC in breast cancer microenvironment

Abstract Background Aberrant post transcriptional modifications of RNA, such as 5-methylcytosine modifications, have been frequently observed in breast cancer (BC). The M5C core catalytic enzyme NSUN2 gene was found to be co-amplified with the oncogenic transcription factor MYC in BC. However, the function of m5C modification in the immune response and metabolism to BC remains unknown. Therefore, we aimed to investigate the crosstalk between NSUN2 and MYC in BC microenvironment. Methods We investigated the function of NSUN2 in breast cancer using vivo and vitro assays. Next, the co-occurrence of NSUN2 and MYC in BC were tested by cBioPortal analysis. Co-immunoprecipitation and mass spectrometry were performed to determine the interact between NSUN2 and MYC. Then, correlation between the expression of NSUN2 and BC microenvironment were explored by CAMOIP, PCR and western-blotting. Additionally, RNA sequencing (RNA-Seq), Gene Set Enrichment Analysis (GSEA) were used to investigate the underlying mechanism of NSUN2 in BC. Results In the current study, increased expression of NSUN2 was observed in BC tissue compared to that in the adjacent normal tissue. Elevated NSUN2 levels were associated with poor prognosis in patients with BC. NSUN2 knockout (KO) suppressed cell proliferation, migration, and invasion; induced apoptosis in vitro; and repressed tumor growth in vivo. Subsequently, we determined NSUN2 can interact with MYC protein, and found that immune infiltration and glycolysis were increased in the NSUN2 KO BC cell line. In addition, RNA sequencing demonstrated that the differentially expressed genes in BC cells after NSUN2 KO were significantly enriched in the negative regulation of immune processes and metabolic processes. Conclusions Overall, NSUN2 overexpression drove immunosuppression and promoted BC progression. NSUN2 can interact with MYC protein, thereby being involved in the functional regulation of MYC target genes. Our findings suggest that NSUN2 may act as a potential therapeutic target for BC in the context of MYC amplification.