BACKGROUND: Cathepsin D is a widely distributed lysosomal acidic endopeptidase. It is an estrogen-regulated protein that is a prognostic factor in breast cancer. The aim of this study was to measure cathepsin D concentrations in thyroid tissues and to correlate these concentrations with clinical and pathologic parameters. METHODS: Cathepsin D and thyroglobulin concentrations were measured in the cytosol of normal thyroid tissues (n = 14), benign nodules (n = 6), and thyroid carcinomas (n = 32) with an immunoradiometric assay. Statistical analysis was based on the Kruskal-Wallis and Wilcoxon tests and on the Spearman rank correlation coefficient. RESULTS: The mean level of cathepsin D, expressed as picomoles per milligram protein minus thyroglobulin, was higher in the 32 carcinomas, 29.1 +/- 15.5, than in the 14 normal thyroid tissues, 8.4 +/- 2.5 (p < 0.001) or in the 6 benign nodules, 11.2 +/- 7.3 (p = 0.003). Cathepsin D concentrations correlated with tumor size; Spearman rank correlation coefficient was rs = 0.44 (p = 0.012). No significant difference was found regarding histologic type. Cathepsin D concentrations were inversely correlated with the thyroglobulin level in the tumor; Spearman rank correlation coefficient was rs = -0.60 (p < 0.001). CONCLUSIONS: Cathepsin D concentration is higher in thyroid carcinoma than in normal thyroid tissue. Increased cathepsin D concentrations correlate with thyroid tumor size but not with histologic type. Further studies should be done to confirm the potential prognostic value of cathepsin D in patients with thyroid carcinomas.
BACKGROUND:Cathepsin D is a widely distributed lysosomal acidic endopeptidase. It is an estrogen-regulated protein that is a prognostic factor in breast cancer. The aim of this study was to measure cathepsin D concentrations in thyroid tissues and to correlate these concentrations with clinical and pathologic parameters. METHODS:Cathepsin D and thyroglobulin concentrations were measured in the cytosol of normal thyroid tissues (n = 14), benign nodules (n = 6), and thyroid carcinomas (n = 32) with an immunoradiometric assay. Statistical analysis was based on the Kruskal-Wallis and Wilcoxon tests and on the Spearman rank correlation coefficient. RESULTS: The mean level of cathepsin D, expressed as picomoles per milligram protein minus thyroglobulin, was higher in the 32 carcinomas, 29.1 +/- 15.5, than in the 14 normal thyroid tissues, 8.4 +/- 2.5 (p < 0.001) or in the 6 benign nodules, 11.2 +/- 7.3 (p = 0.003). Cathepsin D concentrations correlated with tumor size; Spearman rank correlation coefficient was rs = 0.44 (p = 0.012). No significant difference was found regarding histologic type. Cathepsin D concentrations were inversely correlated with the thyroglobulin level in the tumor; Spearman rank correlation coefficient was rs = -0.60 (p < 0.001). CONCLUSIONS:Cathepsin D concentration is higher in thyroid carcinoma than in normal thyroid tissue. Increased cathepsin D concentrations correlate with thyroid tumor size but not with histologic type. Further studies should be done to confirm the potential prognostic value of cathepsin D in patients with thyroid carcinomas.