NSUN4 Facilitates the Activity of Oncogenic Protein CDC20 to Promote NSCLC Development by Mediating m5C Modification of CDC20 mRNA.

Abstract

Background: 5-methylcytosine (m5C) methylation is the crucial posttranscriptional modification of RNA. NSUN4, a methyltransferase for m5C methylation, contributes to lung tumorigenesis. Here, we determined the precise action of NSUN4 on the development of non-small cell lung cancer (NSCLC).

Methods: NSUN4 and CDC20 mRNA expression was detected by quantitative PCR. Western blot and immunohistochemistry were used for the analysis of protein expression. Cell growth, apoptosis, invasiveness, migratory ability, and stemness potential were evaluated by colony formation, flow cytometry, transwell, and sphere formation assays. The influence of NSUN4 in CDC20 mRNA was analyzed using RNA immunoprecipitation (RIP) assay and Actinomycin D (Act D) treatment. Subcutaneous xenograft studies were performed to analyze the function in vivo.

Results: In human NSCLC tumors and cell lines, NSUN4 and CDC20 levels were upregulated. NSUN4 inhibition diminished NSCLC cell growth, stemness, invasiveness, and migratory ability in vitro, while NSUN4 increase had opposite effects. A positive expression association between CDC20 and NSUN4 was observed in NSCLC samples. Mechanistically, NSUN4 enhanced the stability of CDC20 mRNA through m5C modification. CDC20 depletion significantly counteracted NSUN4-driven cell phenotype alterations in vitro. Additionally, inhibition of NSUN4 impeded the growth of A549 NSCLC subcutaneous xenografts in vivo.

Conclusion: Our findings identify the pro-tumorigenic property of the NSUN4/CDC20 cascade in NSCLC. Targeting the novel cascade may be a promising way for combating this deadly disease.