THE REGULATION OF PROLIFERATION AND INVASION IN DIFFERENTIATED THYROID-CANCER BY GROWTH-FACTORS

Invasion and metastasis are the primary cause of death in patients wit h follicular thyroid cancer (FTC). The thyroid is a micro-economic sys tem in which proliferation and differentiation was supposed to be unde r the major control of only a single homone (thyroid stimulating hormo ne - TSH). It has shown, however, that a complex network of various gr owth factors regulates growth and invasion of thyroid cancer cells. A growing literature has established the close association between malig nant tumor progression and growth regulatory aberrations in cancer cel ls. Most of these studies have focused on the phenomenon, that advance d and more aggressive tumors or metastases lost the sensitivity to gro wth inhibitors, such as transforming growth factor beta. These finding s highlight two aberrations of growth regulation which may favour prog ression of malignant disease and acquisition of metastatic competence: (1) Resistence to growth factor inhibitors and (2) growth autonomy of metastatic follicular thyroid cancer cells.