Expression of Matrix Metalloproteinase-2, but not Caspase-3, Facilitates Distinction between Benign and Malignant Thyroid Follicular Neoplasms

Purpose: Definite diagnosis of follicular thyroid carcinoma (FTC) is based on the presence of capsularor vascular invasion. To date, no reliable and practical method has been introduced to discriminate thismalignant neoplasm from follicular thyroid adenoma (FTA) in fine needle aspiration biopsy material. Matrixmetalloproteinase-2 (MMP-2), by degrading extracellular matrix, and caspase-3, by induction of apoptosis, havebeen shown to play important roles in carcinogenesis and aggressive behavior in many tumor types. The aim of thisstudy was to examine expression of MMP-2 and caspase-3 in thyroid follicular neoplasms and to determine theirusefulness for differential diagnosis.
Method: Sixty FTAs and 41 FTCs were analysed immunohistochemicallyfor MMP-2 and caspase-3.
Result: MMP-2 was positive in 4 FTCs (9.8%), but in none of FTAs, with statisticalsignificance (p= 0.025). Caspase-3 was positive in 30 (50%) of FTAs and in 27 (65.9%) of FTCs.
Conclusion: Ourresults show MMP-2 expression only in FTCs and suggest that this protein may be a useful marker to confirmdiagnosis of FTC versus FTA with 100% specificity and 100% predictive value of a positive test. We failed toshow any differential diagnostic value for caspase-3 in thyroid follicular neoplasms.