Additional considerations in cancer cell radioresistance, integrin αvβ3 and thyroid hormones

Background The existence of a functional relationship between a certain thyroid hormone analogue and cancer cell radioresistance has been shown by Leith and coworkers. The hormone analogue with relevance to malignant cells' radioresistance is tetraiodothyroacetic acid (tetrac). Tetrac is the deaminated derivative of L-thyroxine (T4), the principal product of the thyroid gland. Preclinical studies demonstrated that tetrac and chemically modified tetrac (CMT), e.g. a fluorobenzyl-conjugated tetrac analogue, restores radiosensitivity in certain radioresistant tumor cells. Due to their molecular, physico-chemical, and biological properties, actions of CMT analogues are believed to be initiated at the thyroid hormone analogue receptor site on plasma membrane integrin αvβ3.