TMPRSS6: A novel and highly sensitive biomarker outperforming BRAF-V600E for diagnosis and risk stratification of papillary thyroid cancer

Background The BRAF-V600E mutation, while established in papillary thyroid cancer (PTC), exhibits a suboptimal detection rate, limiting its diagnostic and prognostic utility. This study aimed to evaluate transmembrane protease serine 6 (TMPRSS6) as a superior biomarker for PTC diagnosis and risk stratification. Methods We conducted an integrative analysis combining database mining (TCGA), tissue validation, RNA sequencing, and functional assays in PTC cell lines. Diagnostic performance, expression stability between primary and metastatic lesions, and clinicopathological correlations were assessed. A support vector machine model incorporating TMPRSS6 was developed for malignancy diagnosis and the identification of high-risk PTC. Results TMPRSS6 demonstrated high specificity for PTC, with detection rates of 89.2% (TCGA) and 87.5% (in-house cohort), significantly exceeding those of BRAF-V600E (47.5% and 61.3%, respectively). Consequently, TMPRSS6 showed superior diagnostic accuracy (AUC: 0.900 vs. 0.583 for BRAF-V600E). Its expression was consistent across primary and metastatic sites and positively correlated with aggressive features, including extrathyroidal extension and lymph node metastasis. Functional knockdown inhibited PTC cell migration, invasion, and iodine uptake. Clinically, TMPRSS6 accurately diagnosed malignancy in BRAF wild-type patients (91.8%). Its combination with BRAF-V600E achieved a diagnostic accuracy of 93.2%. Integration into a molecular model enabled the precise identification of high-risk PTCs with 90.3% (training) and 98.4% (validation) accuracy. Conclusion TMPRSS6 is a robust biomarker that outperforms BRAF-V600E in PTC diagnosis, particularly in BRAF wild-type cases. It enhances molecular subtyping for the precise identification of high-risk PTC, offering significant clinical utility.