Objectives: The aim of the present study was to examine the expressions of mucin genes MUC1 and MUC4 and to evaluate the difference of their expressions in normal thyroid tissue, follicular adenoma, and papillary carcinoma. Furthermore, we aimed to estimate their prognostic significance in papillary carcinoma.
Methods: We performed semiquantitative reverse-transcription polymerase chain reaction for determining the MUC1 and MUC4 mRNA expressions, and immunohistochemical staining was performed to determine the MUC1 and MUC4 protein expressions in 22 normal thyroid tissues, 22 follicular adenomas, and 15 papillary carcinomas. The semiquantitative scoring of the immunohistochemical staining was compared with the prognostic factors for thyroid carcinoma to evaluate the prognostic significance in 87 papillary carcinoma patients.
Results: The MUC1 mRNA of the papillary carcinoma tissue showed an increased expression level compared with the other tissues. However, the expression level of MUC4 mRNA was weak in all the specimens, and this was not significantly different among the three groups. MUC1 immunoreactivity was more intense in papillary carcinoma but not in the other tissues. MUC4 was not expressed in all thyroid tissues. The expression of MUC1 was significantly associated with tumor size, extrathyroidal spread, and TNM stage (P < .05).
Conclusions: Up-regulation of MUC1 may play a more important role than that of MUC4 in the development of thyroid papillary carcinoma, and it may have some significance as a prognostic factor.