Hormone regulation of the growth of endometrial hyperplasias and tumors from the aged fischer rat.

Abstract A monolayer culture system was developed for growing hyperplastic endometrial cells and endometrial tumor cells derived from aged Fischer 344 rats. This system permits the study of the action of hormones and drugs on growth of rat endometrial cells in a defined system. The growth of the hyperplastic endometrial cells in culture was stimulated by 5 n M 17β-estradiol and inhibited by 1.5 m M , N 6 ,O 2′ -dibutyryl cAMP. Equilibrium binding studies with cAMP and tumor cytosols showed a biphasic Scatchard plot with apparent K d values of 10 and 376 n M cAMP and a binding capacity of 3.0 pmole/mg protein. Normal uterine cytosols exhibited apparent K d values of 11 and 267 n M and a binding capacity of 3.8 pmole/mg protein. Binding studies with 17β-estradiol (E 2 ) and cytosols exhibited apparent K d values of 0.40 and 0.42 n M E 2 and binding capacities of 76 and 115 fmole E2mg protein for normal uterine and endometrial tumor cytosols, respectively. These data indicate that both normal uterine and endometrial tumor cytosols exhibit high-affinity receptor sites for cAMP and E 2 which may mediate the responses of the uterine cells to the actions of cAMP and E 2 . Endometrial tumor cells from the aged Fischer rat thus offer a system to investigate hormone regulation of tumor growth.