Wirkmechanismen ovarieller steroidhormone und antiostrogene in der karzinogenese der mamma und des endometriums

The ovarian steroid hormones (e.g., estrogen and progesterone) exert their many cellular and organ-specific effects via steroidhormone receptors. Steroid-hormon-dependent genes are stimulated by binding of the ligand- receptor complex to the DNA binding site. Most steroid-hormone-receptors in the breast and endometrium are located in the cell nuclei. Additionally, non- genomic effects are mediated by intracellular proteins. Cell activities such as proliferation, differentiation, division and apoptosis are regulated by proto-oncogenes, tumor suppressor genes and mutator genes. Normally various regulatory mechanisms are in balance. Dysfunctions in regulatory mechanisms are key steps in the malignant transformation of cells in the breast or endometrium. Thus, the effects of steroid hormones or anti-estrogens such as tamoxifen or ralofixene can be obviated despite the presence of functional receptors.