Effects of Sex Steroid Hormones on Corticosteroid-Binding Globulin Gene Expression in Human Endometrial Cancer Cell Line Ishikawa

The effect of progestins on intracellular corticosteroid-binding globulin (CBG) mRNA expression in an endometrial cancer cell line (Ishikawa) was examined in an attempt to understand the biological effects of high-dose progestins in the treatment of well-differentiated uterine endometrial cancers. Oestradiol-17β (E2) significantly increased CBG mRNA expression in a dose-dependent manner, while a high dose of progesterone with or without E2 suppressed it significantly. Furthermore, a high dose of progesterone or medroxyprogesterone acetate (MPA) suppressed CBG mRNA expression to a greater degree than did chlormadinone acetate or 17 α-hydroxyprogesterone caproate with or without E2. These findings suggest that the effects of high-dose progestins on cancer cells may be mediated via suppression of intracellular CBG.