Expression Patterns of S100A6 Gene in Human Thyroid Diseases

ABSTRACT

S100A6 (calcyclin) is a member of the S100 family and has been originally isolated from the cDNA library of Syrian baby hamster kidney cells. The S100A6 gene expression is reported to remain high throughout the cell cycle following induction by serum or growth factors, suggesting that the gene may be required for cell cycle progression. Nevertheless, the role that S100A6 may play in tumor progression remains unknown. In this study, we have explored the expression patterns of S100A6 gene in human thyroid tissues by northern blot analysis. Using the S100A6 monoclonal antibody, we carried out the immunohistochemical staining to determine the distribution/localization of S100A6 protein within tumor or non-tumorous cells of the thyroid. To modulate the regulation of endogenously expressed S100A6 protein in the intracellular level, overexpressed or anti-sense treated transfectant was constructed by using the eukaryotic expression vector. As a result, immunohistochemistry for S100A6 showed a strong positivity in the malignant tumors of thyroid and a high expression level of S100A6 protein affected cell proliferation in the overexpressed transfectant. These findings suggest that S100A6 may be involved in the tumor pathogenesis and provides another parameter for the differentiation of malignant and benign lesions. A well defined monoclonal antibody against S100A6 protein is now available for the immunohistochemical studies of the various thyroid tissues.