[Tamoxifen molecular targets different from estrogen receptors]

Experimental studies showing ever new biological effects of tamoxifen on tumor cells, both expressing and nonexpressing estrogen receptors, are providing a novel conception of the drug, likely well known at present. The review describes tamoxifen targets, whose blocking induces inhibition of tumor cell growth and angiogenesis, stimulation of the programmed cell death (apoptosis, autophagia and necrosis), inhibition of multiple drug resistance mechanism and inhibition of invasion and metastasizing. In all the events, the results of the tamoxifen interaction with the cells are prognostically favourable from the viewpoint of both the inhibition of the tumor growth and metastasizing and the susceptibility to the medicinal therapy, that is considered by some authors as an extremely important addition to the tamoxifen antiestrogenic effect. The strategy of long-term tamoxifen adjuvant therapy of breast cancer with positive status of the estrogen reseptors was developed by Craig V. Jordan as far back as in the seventies of the XXth century, however there are arguments allowing to consider it also useful for the treatment of other tumors. First of all it is the fact described lately in regard to expression of estrogen beta-reseptors in solid tumors of practically all known localization and histological types, that are also the targets of tamoxifen. Apart from estimation of estrogen receptors, it is believed by some authors that molecular and biological choice of patients is necessary with an account of expression of other cell targets of antiestrogen for complete realization of all the aspects of tamoxifen biological activity in long-term adjuvant therapy of malignant tumors of various localization.