Immunohistochemical localization of matrix metalloproteinase-2 (MMP-2) in medullary thyroid carcinoma

Background: Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade protein components of the extracellular matrix. These enzymes are believed to play an important role in tumor progression, invasion and metastasis. Materials and methods: We examined the expression of one member of the MMP family, matrix metalloproteinase-2 (MMP-2, collagenase A) in twenty-two paraffin-embedded specimens of medullary thyroid carcinoma (MTC) using an immunohistochemical method and a monoclonal antibody against MMP-2. In addition, we compared MMP-2 expression with clinicopathological data at the time of surgery. Results: Immunohistochemical staining showed moderate to strong positivity in 19/22 cases and weak positivity in 3/22 cases. MMP-2 was immunohistochemically localized mainly in tumor cells, but was also present in surrounding stromal tissue. MMP-2 expression, however, was not associated with histopathological appearance of the tumor tissue, tumor size or the presence of lymph node metastases. Conclusion: Considerble production of MMP-2 is associated with the malignant phenotype of parafollicular thyroid cells, suggesting a potential role of this proteolytic enzyme in tumorigenesis in vivo. However, since MMP-2 expression was not related to clinicopathological data, immunohistochemical staining of MMP-2 does not seem to be helpful in predicting the prognosis of medullary thyroid carcinoma.