The Expression of the High Mobility Group I(Y) mRNA in Thyroid Cancers: Useful Tool of Differential Diagnosis of Thyroid Nodules

OBJECTIVE Thyroid nodule is frequent and occurs in about 5% of the general population. In contrast, thyroid cancer is much less frequent and occurs in about 5-10% of thyroid nodules. Distinguishing between benign and malignant lesions is an important task that is best accomplished by fine needle aspiration. Recently, Chiappetta et al. reported that the expression of the high mobility group (HMG) I(Y) proteins correlates with the malignant phenotype of human thyroid neoplasia, and suggested that the detection of the HMG I(Y) proteins might be a valid tool for an easy and sensitive discrimination assay between benign and malignant neoplastic thyroid disease. METHODS We evaluated the expression of the HMG I(Y) mRNA in 39 frozen thyroid tissues from patients with thyroid nodule by semiquantitative RT-PCR. RESULTS The expression of the HMG I(Y) mRNA was low in all of 10 normal thyroid tissues. In all of 3 adenomatous goiters, 6 follicular adenomas and 2 Hürthle cell adenomas, the HMG I(Y) mRNA expression level was low. In 11 of 13 papillary carcinomas and all of 5 follicular carcinomas, the HMG I(Y) mRNA expression level was high. CONCLUSION These results indicate that there is a correlation between the expression of HMG I(Y) and the malignant phenotype of thyroid cancer, suggesting that these proteins may be useful as a marker in thyroid cancer.