Preventive effects of danazol on endometrial carcinogenesis in mice.

Short and long-term experiments were designed to determine effects of danazol on estrogen-related endometrial carcinogenesis in mice. The short-term assays showed that danazol decreased expression levels of c-fos/jun mRNA and their oncoproteins induced by estradiol-17beta (E2). For the long-term assay, 85 female ICR mice were given N-methyl-N-nitrsourea solution into their uterine corpora. The animals were divided into three groups as follows: Group 1, E2-diet (5 ppm) plus danazol (2 mg/body (s.c.), every 4 weeks); Group 2, E2-diet alone, Group 3, basal diet alone. At 30 weeks, incidences of atypical and complex endometrial hyperplasia were significantly decreased by danazol-treatment. These results suggest that danazol has preventive effects on estrogen-related endometrial carcinogenesis in mice, through the suppression of estrogen-induced c-fos/jun-expression.