Faculty Bibliography

Human fetal membranes, taken from 30 patients submitted to caesarean section during the final stages of gestation and labor, were examined in order to evaluate the presence and characteristics of the oxytocin receptor. The presence of oxytocin receptors in human fetal membranes, both in the amnion and in the chorion-decidua, was demonstrated in this study. The receptor binding to oxytocin showed a significant increase during early and advanced labor compared with before the onset of labor. When the pre-labor level was taken as the normalized form (control = 100) the increase with respect to the control (10 cases) for the amnion in early labor (2.27 times +/- 0.11, mean +/- SEM, P less than 0.001, 10 cases) and in advanced labor (2.53 times +/- 0.15, 10 cases, P less than 0.001) was highly significant. In the chorion-decidua the increase was 1.61 times +/- 0.09, P less than 0.001 in early labor and 1.66 times +/- 0.19, P less than 0.001 in advanced labor. Scatchard analysis showed a single receptor site for oxytocin in amnion and chorion decidua. The dissociation constant (Kd) did not change during the various stages of labor; the mean values found were 0.228 +/- 0.02 (mean +/- SEM) nM in the amnion and 0.193 +/- 0.03 nM in the chorion-decidua respectively. These findings suggest that human fetal membranes are target organs for oxytocin and that they might play a role in the onset of labor through an increase of receptor binding

Arylsulfatase (EC 3.1.6.1) activity in human stromal cells isolated from specimens of histologically normal proliferative endometrium was increased several-fold during culture for 8-15 days in RPMI-1640 medium plus 10% charcoal-treated fetal bovine serum in the presence of a mixture of ovarian hormones (36 nM estradiol, 1 microM medroxyprogesterone acetate, and 100 micrograms/mL relaxin). The changes in sulfatase activity, determined by measuring the rate of formation of estrone from tritiated estrone sulfate, were associated with in vitro decidualization of the stromal cells, as determined by changes in secretion of PRL into daily renewed culture medium. PRL output by the cells during the last 24 h in culture and sulfatase activity in the cells collected at the end of the culture period were related to their DNA and protein contents. Sulfatase activity in the cells cultured in the presence of the ovarian hormones was comparable to the activity found in decidual cells at term pregnancy. PRL added for 1 day to cultures of stromal cells in the absence of exogenous hormones increased sulfatase activity in the cells, probably by acting in an autocrine manner, as previously demonstrated with human decidual cells during pregnancy. These experiments also revealed a hormonal regulation of stromal cell proliferation in vitro, as estimated from measurements of both DNA and protein levels per dish. Augmentation of sulfatase activity can serve as another marker of in vitro decidualization. Physiologically, an increase in this enzymatic activity may result in a preferential estrogenic stimulation of the decidualized cells by utilization of a circulating substrate, estrone sulfate. This hypothesis could explain the preferential retention of progesterone receptors in decidual cells observed immunohistochemically during the late luteal phase of the menstrual cycle, suggestive of a shift in progestogenic actions from the epithelium to the stroma

The hormone sensitivity of endometrial carcinoma is related to the presence of steroid hormone receptors. The determination of progesterone receptors has been proposed in order to predict clinical prognosis and to aid treatment selection. The integrity of the hormone receptor system and postreceptoral events in tumors is essential to endocrine therapy response. Nevertheless, although hormone receptors are present in a large number of endometrial carcinomas, only 30% of cases respond to hormone therapy. In some neoplasms the receptors can be present, but not functioning, or else neoplastic transformation could have induced alterations in processes after hormone-receptor interaction

Steroid receptor levels were determined in 196 samples of endometrial adenocarcinoma: cytosol estradiol receptors (ERc) were measured in 171 samples, cytosol progesterone receptors (PRc) in all samples; nuclear estradiol receptors (ERn) and nuclear progesterone receptors (PRn) in 68 samples; total estradiol receptors (ERt = ERc plus ERn) and total progesterone receptors (PRt = PRc plus PRn) were measured in 68 samples. The ERc levels were 88.2 +/- 8.9 (mean +/- SEM) and ERn were 94.4 +/- 15.6 fmol/mg protein; PRc levels were 197.9 +/- 25.9 and PRn 178.3 +/- 55.9 fmol/mg protein. The ERt levels were 162.6 +/- 23.2 and PRt 249.8 +/- 75.7 fmol/mg protein. The presence of PRc was related to the ERc levels according to the cut-off used. Estradiol receptors (ER) and progesterone receptors (PR) were present in the cytoplasmic and nuclear fractions in 60.2% and 36.8% of cases, respectively. The simultaneous presence of both ERt and PRt was observed only in 27.9% of cases. In the normal endometrium ERc and PRc were negatively correlated (r = -0.525, P less than 0.005), whereas in endometrial adenocarcinoma the correlation was positive (r = 0.491, P less than 0.001). In contrast with the normal endometrium the correlation between ERc and ERn was positive (r = 0.582, P less than 0.001) in tumor tissue. In neoplastic tissue Scatchard analysis showed a single class of specific ERc sites with a dissociation constant (Kd) of 1.39 +/- 0.8 X 10(-9) mol/l, one tenth of that found in the normal premenopausal endometrium. Qualitative and quantitative analysis of the receptor status showed that in 30% to 40% of cases studied the behavior of the neoplastic cell was similar to that found in the normal endometrial cell. In a 4-year follow-up of patients affected by endometrial adenocarcinoma there is better survival in the groups of patients with a simultaneous presence of ERt and PRt than in the group with their absence

The effect of natural beta-interferon (beta-IFN) on steroid receptor levels and output of prostaglandins (PGs) was investigated in human endometrial cancer. beta-IFN determines in endometrial adenocarcinoma explants an increase of cytosolic estradiol (ER) and progesterone (PR) receptors at concentrations ranging from 10 to 1000 IU/ml of culture medium. Only cases in which there was an enhancement of at least 50% with respect to control values were considered. Low concentrations of beta-IFN (10 IU/ml of culture medium) produce an enhancement of ER in 60% and of PR in 42% of cases, while higher concentrations of beta-IFN (1000 IU/ml of culture medium) produce an enhancement of ER in 32%, and of PR in 82% of cases. Since PGs are involved in proliferation control in a large variety of tumors, we evaluated the ratio between PGF2-alpha and PGE2 levels in culture medium. This ratio increased, in our experimental model, after treatment with 10 and 1000 IU/ml of beta-IFN in 38% and 58% of cases respectively. Our data suggest that beta-IFN could affect cellular hormone sensitivity through a modification of ER and PR and it can also determine a variation of PG output in human endometrial cancer

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