NSUN2/FOXM1 positive feedback pathway promotes the malignant development of non-small cell lung cancer
Lin Wang, Dujuan Zhou, Yangjing Ou
Abstract
• FOXM1 expression was upregulated in NSCLC tissues and cells. • FOXM1 silencing inhibited NSCLC cell proliferation, invasion, and M2 macrophage polarization and induced cell apoptosis and ferroptosis. • NSUN2 stabilized FOXM1 expression in a YBX1-dependent manner. • FOXM1 transcriptionally activated NSUN2 in NSCLC cells. • NSUN2 knockdown repressed tumor formation by regulating FOXM1. Non-small cell lung cancer (NSCLC) constitutes the majority of lung cancer cases and is associated with poor prognosis. The forkhead box M1 (FOXM1) transcription factor is implicated in cancer progression, yet the precise mechanisms regulating its activity in NSCLC remain poorly understood. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to assess mRNA expression levels. Immunohistochemistry (IHC) and western blotting were utilized to analyze protein expression. Cell viability was evaluated using a cell counting kit-8 (CCK-8) assay, while 5-ethynyl-2′-deoxyuridine (EdU) assay was used to measure cell proliferation. Cell invasion was determined through a transwell assay. Flow cytometry was performed to quantify CD206-positive M2 macrophages, measure reactive oxygen species (ROS) levels, and analyze cell apoptosis. The colorimetric method was used to analyze Fe 2+ , malondialdehyde (MDA), and glutathione (GSH) levels. M5C methylated RNA immunoprecipitation (MeRIP), RNA immunoprecipitation (RIP), chromatin immunoprecipitation and dual-luciferase reporter assays were conducted to validate the interaction between FOXM1, NOL1/NOP2/Sun domain family, member 2 (NSUN2), and Y-box binding protein 1 (YBX1). In vivo effects of NSUN2 silencing and FOXM1 overexpression on NSCLC cell malignancy were examined using a mouse model assay. FOXM1 expression was elevated in NSCLC tissues and cells. FOXM1 knockdown suppressed NSCLC cell proliferation, invasion, and M2 macrophage polarization, while promoted apoptosis and ferroptosis. In addition, NSUN2 stabilized FOXM1 mRNA through m5C modification and regulated FOXM1 expression in a YBX1-dependent manner. The results also showed that NSUN2 knockdown inhibited NSCLC cell proliferation, invasion, and M2 macrophage polarization, and induced apoptosis and ferroptosis by modulating FOXM1. Moreover, FOXM1 transcriptionally activated NSUN2 in A549 and 95D cells. Further, NSUN2 knockdown repressed tumor formation by regulating FOXM1. The NSUN2/FOXM1 positive feedback pathway accelerated the malignant development of NSCLC, suggesting that targeting this pathway may have significant clinical implications for NSCLC treatment.