The expression of the high mobility group HMGI(Y) proteins correlates with the malignant phenotype of human thyroid neoplasias

High Mobility Group I (HMGI) proteins are nuclear proteins involved in the regulation of chromatin structure and function. Elevated expression of the HMGI proteins (HMGI, HMGY and HMGI-C) has been correlated with the presence of a highly malignant phenotype in epithelial and fibroblastic rat thyroid cells, and in several experimental carcinomas. Here, we demonstrate that HMGI and HMGY proteins are expressed in human thyroid carcinomas and thyroid carcinoma cell lines, but not in adenomas, goiters, normal thyroid tissues and cells. These results indicate a correlation between HMGI and HMGY expression and the malignant phenotype of thyroid neoplasias, suggesting that these proteins may be used as markers in thyroid cancer.