SUMMARY
Thyroid hormones show not only genomic, but also nongenomic activity, which is related to specific membrane, cytoplasmic and organelle receptors. The best known receptors are located on the alpha-V-beta-3 integrin of cell membrane. Their stimulation results in an activation of mitogen-activated protein kinases (MAPKs) or phosphoinositide 3-kinase (PI3K), which directly leads to an inhibition of apoptosis and increased proliferation of tumor cells, as well as promotes angiogenesis and metastasis formation. In ovarian cancer cells L-thyroxine is proven to be involved in MAPK activation as well as in the up-regulation of expression and enhanced cellular accumulation of programmed death ligand 1 (PD-L1), which results in an inhibition of neoplastic cells apoptosis.