[Study of matrix metalloproteinase-2 and -9 in thyroid papillary cancer]

Metastasis of cancer starts with the penetration of cancer cells through the membrane surrounding the cancer focus into the stroma (extracellular matrix). The focal membrane consists of mainly type-IV collagen. An immunochemical study of 28 patients with benign thyroid nodular diseases and 27 patients with papillary carcinoma revealed the fragmentation of type-IV collagen in 4 patients with papillary carcinoma. Matrix metalloprotease (MMP)-2 and MMP-9 are the major enzymes which decompose type-IV collagen, and they have been suggested to be related to cancer metastasis. Therefore, we conducted biochemical and immunohistochemical studies to determine the relationship between these MMPs and the degree of malignancy in thyroid diseases. The concentration of MMP-2 in the serum of patients with papillary carcinoma and patients with benign nodules was 526.0 +/- 96.6 and 522.7 +/- 114.6 ng/ml, respectively, and that of MMP-9 was 53.8 +/- 40.3 and 39.9 +/- 36.0 respectively. There was no significant difference between the two groups in the concentration of either enzyme. The concentration of TIMP-2 in the serum was below the detectable level. On the other hand, the concentration of MMP-2 in the tissue of papillary carcinoma, benign nodules and normal tissue was 12.1 +/- 8.1, 5.7 +/- 4.3, and 0.6 +/- 0.5 ng/mg tissue protein, respectively, and that of MMP-9 was 4.2 +/- 4.1, 2.1 +/- 1.7, and 0.4 +/- 0.3 ng/mg tissue protein, respectively. Concentrations of both enzymes were significantly higher in the papillary carcinoma tissue. Immunohistochemical studies revealed a diffuse granular distribution of MMP-2 in the cytoplasm of the tumor cells. These findings imply that MMP-2 and MMP-9 are related to the degree of malignancy of cancer, especially metastasis.