Objective: In this study, we aimed to investigate the role of RNA N6-methyladenosine demethylase fat mass and obesity-associated protein (FTO ) in head and neck squamous cell carcinoma (HNSCC).
Methods: Clinical data downloaded from The Cancer Genome Atlas (TCGA) database were used to analyze the relationship between mRNA levels of FTO, METTL3, METTL14 , and ALKBH5 , and the overall survival in cancer and para-cancer datasets. FTO  expression in tumor and normal tissues was compared using immunohistochemistry, and its relationship with overall survival was analyzed based on the Kaplan–Meier method. The FaDu cell line with high FTO  levels was chosen from five HNSCC cell lines for further experiments. FTO  was verified as an oncogene in HNSCC by in vitro loss-of-function and overexpression studies, cell proliferation assay, wound healing assay, and identification of expression changes of epithelial–mesenchymal transition (EMT)-related markers. Catenin beta 1 (CTNNB1 ) was confirmed as a downstream target gene of FTO  with additional methods like the GEPIA online tool, qRT-PCR, Western blotting, and dot blot assay.
Results: We found that FTO  expression was significantly upregulated in HNSCC datasets and tissues. Increased FTO  expression indicated a trend towards poor prognosis and was found to promote disease proliferation and migration. Mechanistically, cell proliferation assay, wound healing assay, and identification of expression changes of EMT-related markers demonstrated that FTO  could act as an oncogene in HNSCC. FTO  expression was significantly correlated with CTNNB1  expression. Moreover, it exerted a tumorigenic effect by increasing CTNNB1  expression in an m⁶A-dependent manner.
Conclusion: FTO  promotes head and neck squamous cell carcinoma proliferation and migration by increasing CTNNB1  in an m⁶A-dependent manner.
Keywords: FTO , m⁶A, HNSCC, CTNNB1