Osteopontin (OPN) expression in thyroid carcinoma.

BACKGROUND Osteopontin (OPN) and its interacting partner CEA-cell adhesion molecule (CEACAM1) mediate similar biological functions and have been expressed in several types of cancer. Here we investigated the prognostic significance of OPN in thyroid tumours and correlated our findings with the expression of CEACAM1. MATERIALS AND METHODS 297 human thyroid samples were collected in a tissue microarray and as fresh frozen samples to perform immunohistochemistry and western blotting for OPN and to compare these data with our previously published data on CEACAM1 expression. RESULTS Nearly all normal samples were negative for OPN. Some thyroid adenomas were weakly OPN positive whereas many carcinomas were strongly positive. In contrast to CEACAM1, which was preferentially expressed in metastatic papillary carcinomas, no associations were found between OPN expression and patient age, gender and tumour size. CONCLUSION These results may have future implications for the diagnosis and management of patients with thyroid cancers.