Peripheral and ovarian vein plasma levels of 20alpha-dihydroprogesterone in women with normal menstrual cycles

Suppression of the transformed phenotype and induction of differentiation-like characteristics in cultured ovarian tumor cells by chronic treatment with progesterone

Epidemiological evidence suggests that elevated levels of the pregnancy hormone progesterone might play a role in the reduced risk of women to develop ovarian cancer. In vitro studies have supported this hypothesis by demonstrating negative effects of this hormone on the growth and proliferation of cultured ovarian carcinoma cells. However, little is known about the underlying molecular processes and how progesterone might decrease the risk for ovarian tumors. Therefore, we investigated the effects of chronic hormone treatment on the cell-cycle and transformed phenotype of ovarian carcinoma cell lines in vitro. We found that long-term treatment of these cells with progesterone caused a concomitant reduction of cyclin-dependent kinase (CDK) activity. In parallel, these cells lost their transformed phenotype as indicated by the acquisition of contact inhibition and the loss of anchorage-independence, as well as the reduced expression of tumor markers such as heat shock protein (HSP) 72 and carcinoma antigen (CA) 125. In addition, progesterone-treated cells exhibited characteristics that resembled a more differentiated phenotype. Taken together, our data indicated that progesterone was able to suppress the transformed phenotype of ovarian tumor cells. This observation could serve to explain progesterone's alleged protective effect in ovarian carcinogenesis.

Deoxycorticosterone secretion by the human ovary

Progesterone (P), deoxycorticosterone (DOC), estradiol-17 beta (E2) and cortisol (F) were determined simultaneously in the peripheral and the ovarian veins in 13 patients. Blood was collected either by direct sampling during laparotomy (12 patients) or by selective catheterization (1 patient). In all ovarian effluents P and E2 levels were significantly higher than in the peripheral vein. This was also true for DOC except in one ovarian effluent. The gradient was higher on the side of the corpus luteum-bearing ovary. P and E2 levels were correlated in ovarian as well as in peripheral veins. In ovarian effluents, DOC gradients were only significantly correlated with P levels (r = 0.63; P less than 0.01) suggesting a metabolic relationship between the two steroids.

Labor in humans: 1. Progesterone, 20 alpha-dihydro-progesterone, estrone and 17 beta-estradiol in near placental and most distant human amnion and chorion laeve in various stages of labor at term

In some species the onset of labor is regulated by changes in the estrogen/progesterone ratio. The same change in fetal membranes has been suggested to be one of the triggering mechanisms of labor in humans. In order to examine if a gradient in steroid concentration existed in fetal membranes and if changes in concentrations could be observed with the onset and advancing labor, the concentration of progesterone (P), 20 alpha-dihydro-progesterone (20 alpha-OHP), estrone (E1) and 17 beta-estradiol (E2) were determined by specific radioimmunoassay in the near placental and most distant regions of human amnion and chorion laeve obtained at term, before, at the onset and in advanced labor. Both estrogen and progestin concentrations in the chorion were higher than in the amnion. No gradient in the concentration of steroids was found. No statistically significant differences in estrogen and progestin levels were associated with the onset of labor.

Corpus luteum function during the early puerperium

Progesterone and 17 beta-estradiol peripheral plasma levels have been determined during labor and after 1, 3, 6, 12, 24, 48, 72, 96, 120 and 144 h from delivery in a group of 7 women, whose corpus luteum had been removed at delivery and in a corresponding control group with intact corpus luteum. In both groups the results indicate a progressive fall of progesterone and 17 beta-estradiol, that is evident until 144 h for progesterone and 72 h from 17 beta-estradiol. The analysis of the two groups with the Student's t test has shown significantly lower levels in the group of women, whose corpus luteum had been removed, at the 6th h (p less than 0.01), 12th h (p less than 0.02) and 24th h (p less than 0.05) for progesterone and at 3rd h (p less than 0.01) and 6th (p less than 0.01) for 17 beta-estradiol. The significant difference for progesterone appearing later than for 17 beta-estradiol could be due to the fact that progesterone is also dismissed by the adipose tissue, where it is stored. A further statistical elaboration of the results, carried out by calculating the regression line and the transfer function, confirmed the different pattern in time of progesterone and 17 beta-estradiol plasma levels after delivery in the two groups of patients considered.