Downregulated METTL14 Expression Correlates with Breast Cancer Tumor Grade and Molecular Classification

It is unclear whether the methyltransferase-like 14 (METTL14) protein promotes or suppresses cancer growth. We examined the association between METTL14 expression, cancer progression, and patient prognosis in a total of 398 breast cancer tissue specimens. Significantly fewer cancer tissue specimens compared with normal breast tissue expressed high levels of METTL14 (52.8% vs. 75.0%). METTL14 expression was negatively associated with tumor grade and positively associated with patient age, estrogen, and progesterone receptor status. High METTL14 expression was more common in luminal A and luminal B tissue (75.9% and 60.8%, respectively), compared with human epidermal growth factor receptor 2- (HER2-) enriched and triple-negative breast cancer (TNBC) samples (38.2% and 18.6%, respectively). In multiple logistic regression analysis, independent predictors of METTL14 expression in breast cancer included higher tumor grade (odds ratio (OR) = 0.494, 95% confidence interval (CI): 0.289-0.844; P = 0.010), TNBC subtype (OR = 0.109, 95% CI: 0.054-0.222; P < 0.001), and HER2-enriched subtype (OR = 0.298, 95% CI: 0.156-0.567; P < 0.001). No clear relationship was observed between patient prognosis and METTL14 expression. It appears that downregulated METTL14 expression in breast cancer is associated with tumor grade and molecular classification.