METTL3‐mediated ALDH m6A methylation regulates the malignant behavior of BMI1+HNSCC stem cells

Abstract Objectives To reveal the effect and mechanism of methyltransferase‐like 3 (METTL3) on cancer stem cells (CSCs) of head and neck squamous cell carcinoma (HNSCC). Materials and Methods First, we analyzed 14‐HNSCC‐patients’ scRNA‐seq dataset and TCGA dataset of HNSCC. Then, Mettl3 knockout or overexpression mice models were studied via tracing and staining technologies. In addition, we took flow cytometry sorting and sphere formation assays to observe tumorigenicity and used cell transfection and western blotting to verify target protein expression levels. Furthermore, methylated RNA immunoprecipitation sequencing (MeRIP‐seq) and MeRIP‐quantitative real‐time PCR (MeRIP‐qPCR) were taken to identify the mechanism of Mettl3 regulating Bmi1 + CSCs in HNSCC. Results Due to SOX4 transcriptional regulation, METTL3 regulated the malignant behavior of BMI1 + HNSCC stem cells through cell division pathway. The progression and malignancy of HNSCC were decreased after Mettl3 knocked‐out, while increased after Mettl3 knocked‐in in Bmi1 + CSCs in vivo. Knockdown of Mettl3 inhibited stemness properties of CSCs in vitro. Mechanically, Mettl3 mediated the m 6 A modification of ALDH1A3 and ALDH7A1 mRNA in Bmi1 + HNSCC CSCs. Conclusion Regulated by SOX4, METTL3‐mediated ALDH m 6 A methylation regulates the malignant behavior of BMI1 + HNSCC CSCs through cell division pathway.