Overexpressions of c-fos/jun mRNA and their oncoproteins (Fos/Jun) in the mouse uterus treated with three natural estrogens

To further understand hormonal carcinogenesis of natural estrogens (estrone, 17β-estradiol (E2) and estriol), we determined the expressions of c-fos/jun mRNA, and their oncoproteins (Fos/Jun) with intracellular localization in the uterus of ovarectomized mice treated with these estrogens. Mid-term chronic, as well as short-term assays were examined. Of three estrogens examined, mid-term chronic E2-treatment significantly increased the expression of c-fos/jun mRNA, and their oncoproteins (Fos/Jun). These were most prominently expressed in glandular cells of Entreated mouse endometrium. Therefore, mid-term chronic E2-treatment might partially induce glandular cell transformation of uterine endometrium via overexpression of Fos/Jun.