Expression of matrix metalloproteinase-2 and its tissue inhibitor-2 in fetal and neoplastic thyroid tissue and their significance as diagnostic and prognostic markers in papillary carcinoma

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) have roles in physiological and pathological processes. We evaluated immunohistochemical expression of MMP-2 and TIMP-2 in paraffin sections of 12 human fetal thyroids at mid-term gestation and 79 thyroid tumors of follicular origin. Besides evaluating expression of these proteins during fetal development and neoplastic transformation, we determined whether expression of MMP-2 and TIMP-2 may help to differentiate papillary thyroid carcinoma (PTC) from follicular thyroid adenoma (FTA) and/or peritumoral tissue (PT). We also investigated their relationship with prognostically important clinicopathological parameters of PTC. Immunoreactive MMP-2 and TIMP-2 were found in all fetal thyroid tissues examined. Tumor tissues contained variable amounts of MMP-2 and TIMP-2, with overexpression of these proteins in PTC compared to FTA and PT tissue. According to the statistical analysis, MMP-2 distinguished follicular variant of PTC from FTA and overall PTC from total nonmalignant lesions. In PTC, high MMP-2 expression correlated with lymph node metastasis (P = 0.022), while high TIMP-2 expression was positively correlated with tumor size (P = 0.049) and extrathyroid invasion (P = 0.017). Overall, these results indicate a role for MMP-2 and TIMP-2 in both thyroid development and malignant transformation and suggest that positive immunohistochemistry for MMP-2 and TIMP-2 might support diagnosis of PTC and predict unfavorable biological behavior.