Waterpipe Smoke-Induced N6-Methyladenosine Modification Promotes the Progression of Oral Squamous Cell Carcinoma

Background Waterpipe smoking (WPS) is increasingly recognized as a risk factor for oral squamous cell carcinoma (OSCC), but the molecular mechanisms are still not well understood. Emerging evidence emphasizes the role of m6A RNA methylation in cancer development and progression, with METTL3 serving as a key regulator of m6A. This study investigates METTL3 expression and its impact on epithelial-mesenchymal transition (EMT) and cell proliferation in OSCC exposed to waterpipe smoke condensate (WPSC). Methods CAL27 OSCC cells were treated with WPSC, and the expressions of METTL3, its target oncogene HMGA2, and EMT markers were analysed using quantitative PCR and Western blotting. Cell proliferation, clonogenic assays, and METTL3 inhibition were conducted for functional studies. METTL3 expression was evaluated in both primary and metastatic OSCC tissues and further validated using TCGA-OSCC datasets. Protein-protein interactions and functional enrichment analyses were also performed. Results WPSC treatment significantly increased METTL3 and its target HMGA2, as well as the expression of EMT markers in OSCC cells ( P < .001). Inhibiting METTL3 suppressed WPSC-induced HMGA2 expression, EMT, and clonogenic potential. Patient tissues and TCGA-OSCC dataset analyses verified that METTL3 was highly expressed in metastatic and smoking-related OSCCs ( P < .001). Functional enrichment results suggest METTL3 plays a critical role in tumour progression. High HMGA2 expression is correlated with poor prognosis and resistance to PD-L1 immunotherapy. Conclusions WPSC promotes OSCC progression by increasing METTL3 levels, which enhances HMGA2 expression and facilitates EMT. Targeting METTL3 could be an effective therapeutic approach and a useful biomarker for metastatic, tobacco-related OSCC. Clinical relevance Elevated levels of METTL3 induced by waterpipe smoke lead to OSCC progression via HMGA2 and EMT, highlighting METTL3 as a potential biomarker and therapeutic target in OSCC caused by smoking.