Preventive Effects of Glycyrrhizae radix Extract on Estrogen‐related Endometrial Carcinogenesis in Mice

Short‐ and long‐term experiments were conducted to examine the effects of Glycyrrhizae radix (Gl radix) extract on mouse endometrial carcinogenesis. Gl radix treatment (2 weeks) decreased the levels of c‐fos/jun mRNA and the corresponding oncoproteins induced by estradiol‐17β(E(2)) in castrated mice uteri, as determined by reverse transcription‐polymerase chain reaction and Southern blot analysis, and immunohistochemical methods, respectively. For the long‐term assays, 98 female ICR mice were given N‐methyl‐N‐nitrosourea (MNU) solution (1 mg/100 g body wt.) and normal saline (as controls) into their left and right uterine corpora, respectively. They were divided into four groups as follows: group 1 was given 0.625%Gl radix‐ and 5 ppm E2–containing diet; group 2, 5 ppm E2–containing diet; group 3, 0.625%Gl radix‐containing diet; and group 4, the basal diet alone. Gl radix treatment significantly decreased uterine weights and the incidences of uterine endometrial atypical hyperplastic and malignant lesions. It is suggested that Gl radix has inhibitory effects on E(2)‐related endometrial carcinogenesis in mice, through suppression of estrogen‐induced c‐fos/jun‐expressions.