Stomatin-like protein 2 overexpression in papillary thyroid carcinoma is significantly associated with high-risk clinicopathological parameters and BRAFV600E mutation.

Stomatin-like protein 2 (SLP-2), a member of the stomatin protein family, has emerged as a potential molecular hallmark of tumor progression in several human malignancies. The aim of this study was to analyze SLP-2 expression pattern in benign and malignant thyroid tumors (n = 210) and to examine its relationship with clinicopathological parameters and BRAFV600E mutation in thyroid cancer. SLP-2 immunohistochemical expression was not detected in benign adenomas and was absent/weak in follicular and anaplastic carcinomas. High expression levels of SLP-2, found only in papillary thyroid carcinoma (PTC), particularly in the classical variant, were significantly associated with adverse clinicopathological parameters: lymph node metastasis (p = 0.002), extrathyroid invasion (p < 0.001), pT status (p < 0.001), and advanced tumor stage (p = 0.001). Additional genotyping of PTC cases for the BRAFV600E mutation revealed for the first time a close relation between SLP-2 overexpression and the presence of BRAF mutation (p = 0.02) with high positive rates of lymph node metastasis (70%) and extrathyroid invasion (80%) in these cases. The significant association of SLP-2 overexpression with unfavorable clinicopathological characteristics and BRAFV600E mutation indicates that SLP-2 may have a role in aggressiveness of BRAF-mutated PTC and that SLP-2 evaluation could be clinically useful in identification of high-risk PTC patients.