Biological effects of thyroid hormones

The article presents the findings from the study on multifunctional effects of thyroid hormones in relation to normal and malignantly transformed tissues and cells. Both “rapid” and «slow» effects of thyroid hormones including calorigenic effects and effects over adenylate cyclase – cAMP system have been described. Thyroxin (Т4) has been established capable to inhibit proliferation and to induce apoptosis of cells carrying Т4 receptors on their membranes as well as to change course of metabolic processes under its effect. Spectrum of Т4 targets is quite broad to include not only cells of hormone-producing organs, to name those of the breast and the colon, but also other types of cells to name melanin-containing ones; Т4 effects resulting in reconstruction of presentation of regulatory proteins on the cell membrane surface to ultimately activate the process of cell apoptosis. Our findings help determine alternative paths for hormonal regulation of cell proliferation and apoptosis of cells of hormone-dependent tumors, breast cancer, in particular, upon impossibility to regulate the processes by conventional methods. This facilitates understanding mechanisms for activation of signal system of the breast cancer’s cells by hormones upon changes in expression of receptors on the cells’ surface, making possible development of novel strategy for replacement therapy of hormone-dependent tumors upon low efficacy of drug therapy