Progesterone and estradiol-17-beta concentration in human endometrial carcinoma and the effect of progesterone on [3H]-thymidine incorporation

The influence of progesterone and androgens on the growth of endometrial carcinoma

BACKGROUND

The prognosis for endometrial cancer is correlated to the proliferative activity, expressed as the fraction of cells in the synthesis phase (S-phase fraction [SPF]). Progesterone has an antiproliferative effect on the normal endometrium. Its effect in endometrial adenocarcinoma has not been investigated in such detail.

METHODS

The SPF in tumor tissue and serum levels of progesterone, androstenedione, and testosterone were measured in 78 postmenopausal women with the diagnosis of endometrial adenocarcinoma.

RESULTS

No correlations were found between the SPF and androstenedione or testosterone level. No linear correlation between the progesterone concentration and the SPF was revealed when all the patients were analyzed. The material was then divided into subgroups according to the tumor grade and ploidy level. A stepwise analysis based on the progesterone concentration showed that, in well-differentiated and moderately differentiated tumors, the growth rate, expressed as the SPF, fell when progesterone reached a serum level above 0.8 nM.

CONCLUSIONS

Endogenous progesterone plays a role in the control of the tumor's proliferation activity and, consequently, might be significant in the prognosis.

Inhibition of 17 beta-hydroxysteroid dehydrogenase activity in human endometrium by adrenal androgens

The effect of dehydroepiandrosterone sulphate (DHA-S) and its metabolites dehydroepiandrosterone (DHA) and 5-androstene-3 beta, 17 beta-diol (ADIOL) on the activity of 17 beta-hydroxysteroid dehydrogenase in human endometrial tissue was investigated by an isotope ratio technique. The apparent KM for oestradiol was 1.59 X 10(-6) M. All three androgens inhibited the metabolism of oestradiol and the apparent Ki values were: ADIOL, 2.05 X 10(-6) M; DHA-S and DHA, 1.59 X 10(-6) M. However, ADIOL acted by direct competition with oestradiol for the active enzyme site whereas inhibition by DHA and its sulphate was non-competitive. DHA-S and DHA were more potent inhibitors of oestradiol metabolism than was ADIOL. These results support the hypothesis that adrenal androgens could be involved in the development of endometrial hyperplasia and adenocarcinoma. Inhibition of oestradiol metabolism could increase the concentration of oestradiol in endometrial tissue and if unopposed by progesterone, e.g. after the menopause or in subjects with ovulatory defects, could stimulate abnormal endometrial growth.