Expression of Cell Cycle Regulators in Thyroid Neoplasms Originating from Follicular Cells

Yasuhiro      Ito

Abstract

Thyroid carcinoma arising from normal follicular cells is generally slow-growing with an excellent prognosis if competently resected. However, once the tumor dedifferentiates and becomes undifferentiated (anaplastic) carcinoma, it becomes one of the most aggressive malignancies. Such a polarized characteristic is quite unique yet typical of thyroid carcinoma. To date, many researchers have studied differences in the characteristics of thyroid carcinoma before and after dedifferentiation. In this review, the difference in cell proliferating activity and the expression of cell cycle modulators is addressed. Cell proliferating activity of undifferentiated carcinoma is definitely higher than that of differentiated carcinoma. However, expression of cell cycle modulators in thyroid carcinoma is often unique and even discrepant. Some negative modulators are diffusely expressed and reduced expression of some positive modulators can be observed in undifferentiated carcinoma. We described these interesting findings in thyroid carcinoma in this review.

Keywords: thyroid cancer, cell cycle, cell proliferation

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