M6A-induced transcription factor IRF5 contributes to the progression of cervical cancer by upregulating PPP6C

Cervical cancer (CC) is a gynaecological malignancy tumour that seriously threatens women's health. Recent evidence has identified that interferon regulatory factor 5 (IRF5), a nucleoplasm shuttling protein, is a pivotal transcription factor regulating the growth and metastasis of various human tumours. This study aimed to investigate the function and molecular basis of IRF5 in CC development. IRF5, protein phosphatase 6 catalytic subunit (PPP6C) and methyltransferase-like 3 (METTL3) mRNA levels were evaluated by quantitative real-time (qRT)-polymerase chain reaction (PCR). IRF5, PPP6C, METTL3, B-cell lymphoma 2 and Bax protein levels were detected using western blot. Cell proliferation, migration, invasion, angiogenesis and apoptosis were determined by using colony formation, 5-ethynyl-2'-deoxyuridine (EdU), transwell, tube formation assay and flow cytometry assay, respectively. Glucose uptake and lactate production were measured using commercial kits. Xenograft tumour assay in vivo was used to explore the role of IRF5. After JASPAR predication, binding between IRF5 and PPP6C promoter was verified using chromatin immunoprecipitation and dual-luciferase reporter assays. Moreover, the interaction between METTL3 and IRF5 was verified using methylated RNA immunoprecipitation (MeRIP). IRF5, PPP6C and METTL3 were highly expressed in CC tissues and cells. IRF5 silencing significantly inhibited cell proliferation, migration, invasion, angiogenesis and glycolytic metabolism in CC cells, while induced cell apoptosis. Furthermore, the absence of IRF5 hindered tumour growth in vivo. At the molecular level, IRF5 might bind with PPP6C to positively regulate the expression of PPP6C mRNA. Meanwhile, IRF5 was identified as a downstream target of METTL3-mediated m6A modification. METTL3-mediated m6A modification of mRNA might promote CC malignant progression by regulating PPP6C, which might provide a promising therapeutic target for CC treatment.