Localization of estrogen and progesterone receptors in the endometrium of common marmosets Callithrix jacchus

In the present study, changes in the immunohistochemical localization of endometrial estrogen receptor (ER) and progesterone receptor (PR) during various stages of the ovarian cyclicity in common marmoset, have been reported. Ovarian cyclicity was monitored by estimating plasma estradiol and progesterone. During the early follicular phase, weak ER immunolocalization was observed in the endometrial stroma. During the late follicular phase under the influence of rising estradiol levels, stromal ER localization was intense. During the luteal phase, ER localization was absent in the stroma indicating that high concentrations of progesterone suppressed ER. PR localization was not observed in the stroma during the early follicular phase, while weak staining was seen in the stroma during the late follicular phase. PR localization was maximum during the mid luteal phase. However in marmoset, endometrial ER and PR localization was restricted only to the stroma. This unique feature may be due to the characteristic reproductive profile of this nonmenstruating species and needs to be studied further. Thus it can be hypothesized that in the marmoset endometrium, steroid hormone mediated effects possibly occur directly in the stroma and are then transmitted to the epithelium by autocrine/paracrine action of growth factors and cytokines.     

Estrogen receptors, progestin receptors and DNA synthesis in the macaque endometrium during the luteal-follicular transition

We have suggested that in the nonhuman primate endometrium, stromal cells might play a role in mediating the effects of estrogen on the epithelium, especially during the luteal-follicular transition (LFT) when target cells normally escape from the inhibitory influence of progesterone (P). We now report that like estrogen receptors (ER), endometrial progestin receptors (PR) are detectable only in stromal cells until the fifth day of the LFT. With a technique that combined immunocytochemistry and autoradiography on the same sections, we characterized the cellular distribution of ER or PR coincidentally with the localization of [3H]thymidine taken up in vitro by endometria from monkeys undergoing an LFT. DNA synthesis in the glands of the upper endometrium was E2-dependent, but the distribution of [3H]thymidine was not positively correlated with the presence of ER or PR. Readministration of P to animals on days 3 or 4 of the LFT significantly reduced the [3H]thymidine labeling index of the glandular epithelium and caused stromal ER to decline, but P did not block the eventual appearance of ER in epithelial cells on day 5 of the LFT. Thus, E2 stimulated DNA synthesis in epithelial cells that lacked ER, and P suppressed DNA synthesis in these cells even though PR was only detected in the stroma when P treatment began. These data are consistent with a role for endometrial stromal cells in mediating the effects of E2 and P on the epithelium during the LFT.     

Estrogen and progestin receptors in human uterus: reference ranges of clinical conditions

Estrogen receptor (ER) and progestin receptor (PR) levels and their respective dissociation constants (Kd) were determined by titration assay and Scatchard analyses in 319 human uteri. Levels of receptors were neither age nor uterine weight dependent. ER was higher in postmenopausal patients while PR levels were lower in women under 25 years of age. ER ranged from undetectable to 560 fmol/mg cytosol protein (mcp) while PR levels were generally 10-fold greater with a mean of 791 fmol/mcp. The mean of the Kd of ER was 4.0 X 10(-10) M while that for the PR was 9.2 X 10(-10) M. Receptor levels were not correlated with their respective Kd values nor with the Kd of the other receptor; therefore ligand affinities were not receptor concentration dependent. A population of patients was identified (12.5% of the total) in which the ER levels were undetectable while their corresponding PR ranged from 38 to 2,100 fmol/mcp. This suggests the existence of a type of PR which may not require ER for its expression and is independent of the phase of the cycle. Both ER and PR content were significantly elevated in the proliferative phase of the cycle. Evaluation of results as a function of histopathological features showed no relationship between the ER and PR of patients with anovulatory bleeding versus pathology. Uteri with leiomyomas contained ER and PR at levels comparable to those of histologically normal uteri. Adenomyosis patients tended to have lower ER and higher PR levels than the normal uteri. Reference ranges have been established for these receptors in uteri as a corollary to studies of these proteins in endometrial cancer.     

Immunocytochemical analysis of estrogen and progestin receptors in uteri of steroid-treated and pregnant cats.

The purpose of this study was to determine the distribution of estrogen receptors (ER) and progestin receptors (PR) in specific uterine cell populations during various steroid hormone treatment regimens, and to determine if ER and PR distribution in the uterus is altered during implantation and the establishment of pregnancy in the cat. The tissues were processed for indirect immunocytochemical localization of receptors using specific monoclonal antibodies against ER and PR. ER were present in the nuclei of all epithelial cells and stromal fibroblasts in endometrium obtained from ovariectomized animals, whereas PR were only detectable in the nuclei of stromal fibroblasts. There was an apparent increase in the staining intensity and number of nuclei that stained positively for both ER and PR in all cell populations after 14 days of estradiol treatment. The administration of progesterone for 14 and 21 days, in the presence or absence of continuous estradiol, reduced the apparent intensity of staining and the number of nuclei staining positively for both ER and PR. ER were undetectable in the luminal epithelium, but remained in the glandular epithelial cells and stromal fibroblasts, whereas PR were only detectable in stromal fibroblasts. ER and PR localization in the endometrium obtained from estrus animals was similar to that observed in the estradiol-treated animals. A general decrease in intensity of staining for both ER and PR was evident by Day 5 postcoitus in pregnant animals. This decrease in intensity of staining continued until Day 12 postcoitus, when the distributions of ER and PR were similar to those observed in the ovariectomized estradiol-primed, progesterone-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regulation of progesterone receptors and decidualization in uterine stroma of the estrogen receptor-alpha knockout mouse

Regulation of progesterone receptor (PR) in uterine stroma (endometrial stroma plus myometrium) by estrogen was investigated in estrogen receptor-alpha (ERalpha) knockout (alphaERKO) mice. 17 beta-Estradiol (E(2)) increased PR levels in uterine stroma of ovariectomized alphaERKO mice, and ICI 182 780 (ICI) inhibited this E(2)-induced PR expression. Estrogen receptor-beta(ER beta) was detected in both uterine epithelium and stroma of wild-type and alphaERKO mice by immunohistochemistry. In organ cultures of alphaERKO uterus, both E(2) and diethylstilbestrol induced stromal PR, and ICI inhibited this induction. These findings suggest that estrogen induces stromal PR via ERbeta in alphaERKO uterus. However, this process is not mediated exclusively by ERbeta+, because in ERbeta knockout mice, which express ERalpha, PR was up-regulated by E(2) in uterine stroma. In both wild-type and alphaERKO mice, progesterone and mechanical traumatization were essential and sufficient to induce decidual cells, even though E(2) and ERalpha were also required for increase in uterine weight. Progesterone receptor was strongly expressed in decidual cells in alphaERKO mice, and ICI did not inhibit decidualization or PR expression. This study suggests that up-regulation of PR in endometrial stroma is mediated through at least three mechanisms: 1) classical estrogen signaling through ERalpha, 2) estrogen signaling through ERbeta, and 3) as a result of mechanical stimulation plus progesterone, which induces stromal cells to differentiate into decidual cells. Each of these pathways can function independently of the others.     

Estrogen and progesterone receptors in some human myeloma cell lines and murine hybridomas

The control of immune responses by sex hormones is well documented but the effect of sex hormones on lymphoid cell subsets is poorly understood. We have investigated the expression of receptors for androgens (AR), estradiol (ER) and progesterone (PR) by human cell lines of the B lymphocyte lineage and by murine myeloma or hybridomas. AR, ER and PR were determined by cytosol and nuclear binding assays. Eleven human lymphoblastoid cell lines obtained by in vitro infection of blood or tonsil B cells with Epstein-Barr Virus (EBV) B95, did not express AR or ER. Similarly, 10 Burkitt's lymphoma cell lines were AR, ER and PR negative with the exception of the pre-B RAJI cells which bear AR. Among 13 cell lines derived from patients with multiple myeloma none expressed AR but five were found to bear ER (20-164 fmol/mg DNA or 5-10 fmol/mg protein). Four of the latter group also bear PR (86-450 fmol/mg DNA). Two mouse hybridomas out of seven tested were ER and PR positive. The MOPC 315 myeloma expressed ER but not PR. The possible functional role of these sex hormone binding sites in cell proliferation and immunoglobulin secretion deserves further investigation.     

Steroid receptors in canine endometrial cells can be regulated by estrogen and progesterone under in vitro conditions

The expression of estrogen (ER) and progesterone receptors (PR) in the endometrium is regulated by steroid hormones. An increase in plasma estrogen leads to upregulation of the number of both steroid receptors, whereas a decrease in both receptors population is due to high concentration of plasma progesterone. To study the exact effect of different concentrations of beta-estradiol and progesterone on canine epithelial and stromal endometrial cells an in vitro model from dog uterus was developed and kept for 20 days. Material was obtained from healthy dogs, undergoing ovariohysterectomy. Endometrial epithelial and stromal cells were gained after collagenase treatment, followed by filtration steps. Electron microscopy and immunolabeling were used to study cell morphology and differentiation. Immunocytochemistry was used to determine proliferation rate (Ki-67), ER and PR status on Days 3, 8, 10, 13, and 20. Mitotic activity of both cells was stimulated with different concentrations of steroids and revealed high values until cells reached confluency. ER and PR expression in confluent layer from epithelial and stromal cells was upregulated with beta-estradiol. In addition progesterone significant downregulated both receptors population in stromal cells, whereas the reduction was less pronounced in epithelial cells. Results showed that our in vitro system is a useful tool to study the influence of beta-estradiol and progesterone on cell proliferation rate, ER and PR expression. The primary cell culture model helps to avoid experiments on living animals.     

Detection of estrogen alpha and progesterone receptors and cell proliferation in the uterus during early pregnancy in the goat

The objectives of this study were to investigate in the goat uterus the expression of estrogen-alpha (ER alpha) and progesterone receptors (PR) and their relationship to proliferation indices (Ki-67) during peri-implantation on Days 22 to 30 post coitum (pc). Immunohistochemical methods were used to quantify ER alpha and PR for luminal and deep regions of the endometrium and of the myometrium. On Day 22 pc cell proliferation was only observed in the luminal epithelium. On Day 24 pc, high cell proliferation indices were seen in luminal epithelium and proliferation began in the luminal stroma and glands. There was a positive correlation between Ki-67 and total ER alpha score in the luminal epithelium (r = 0.53, P < 0.01). Levels of PR scores were highly correlated with Ki-67 indices in luminal epithelium (r = 0.74, P < 0.01) and stroma (r = 0.70, P < 0.01). No Ki-67 expression was observed in deep glands, stroma or myometrium on any of the days studied. Results indicate that patterns of ER alpha and PR expression differ markedly, and that there was a high correlation between PR expression and cell proliferation in the caprine uterus during the peri-implantation period.     

Aromatase cytochrome P450 and estrogen and progesterone receptors in uterine sarcomas: correlation with clinical parameters

We examined the immunohistochemical expression of aromatase cytochrome P450 (P450arom), estrogen receptor (ER), progesterone receptor (PR), and Ki-67 in postoperative uterine sarcomas (n = 31) and the corresponding eutopic endometria (n = 20) to evaluate the relationships between the endocrine character of uterine sarcomas and the clinical features. In sarcoma tissues, P450arom was detected in 55% of cases, ER in 42%, PR in 42%, and Ki-67 in 90%. In eutopic endometria, P450arom was detected in 60% of cases, ER in 60%, and PR in 35%. There were correlations in the steroid-related proteins between the tumors and endometria (P = 0.001-0.026). The positivity of endometrial P450arom (P = 0.04) and ER (P = 0.006) was higher in surviving patients than dead patients regardless of the menstrual state. The results demonstrate correlation between the expression of P450arom, ER, and PR in tumors and eutopic endometria. Intense expression of the steroid-related proteins was associated with better survival.     

Epidermal growth factor receptors in human breast and endometrial carcinomas

The incidence and levels of epidermal growth factor receptor (EGFR) were studied in 67 breast tumors and 22 endometrial carcinomas. Estrogen receptors (ER) were also measured in all samples and progesterone receptors (PR) were analyzed in 57 breast samples and 21 endometrial tumors. A high level of EGFR expression is found in both breast and endometrial carcinomas, although the incidence of EGFR content is greater in breast carcinomas. 36% of breast tumors had EGFR at levels 3-49.5 fmol/mg membrane protein, whereas this percentage of positivity was 27% for endometrial tumors. In 51% of breast carcinoma and 73% of endometrial tumors, there was a positive ER content, whereas 53% of breast tumors and 62% of endometrial carcinomas were positive. A clear inverse relationship between EGFR content and ER and PR status has been observed in breast tumors. Our data confirm the previously described inverse correlation between expression of EGFR and estrogen receptors in human breast cancer. We also show here that there is a similar inverse relationship between EGFR content and ER levels in endometrial tumors.     

The influence of exogenous steroid hormones on steroid receptors, uterine histological structure and the bacterial flora of the normal bitch.

Oestrogen (ER) and progesterone (PR) receptors have been shown to vary in both concentration and distribution during the oestrous cycle of the bitch, influenced by the normal changes in endogenous reproductive hormones. The influence of exogenous steroid hormones on steroid receptors and the histological structure of the uterus was studied in two groups of parous Beagle bitches. Group A (n = 6) were treated with progesterone (P4) in oil i.m. (3 mg/kg) in late metoestrus on the day that peripheral plasma P4 concentrations were first identified as <10 ng/ml, and subsequently once weekly on three other occasions. Group B (n = 6) were treated with a single i.m. injection of MPA (50 mg, 4.2-5.6 mg/kg) following the same protocol. Full-thickness uterine wall biopsies were obtained from the mid part of one horn 2-7 days after the last (fourth) injection of P4 or MPA. During the subsequent oestrus, when peripheral plasma P4 concentrations were between 8 and 10 ng/ml, each bitch in both groups (n = 12) received a single injection of oestradiol benzoate (ODB) in oil i.m. (7.5 mg, 0.63-0.84 mg/kg). All bitches had an ovariohysterectomy 7 days later. Full-thickness uterine wall samples were obtained from the mid part of the intact horn and other parts of the uterus. Swabs were taken from the uterine lumen for bacteriological examination; all were sterile. Tissue samples were sectioned and examined for evidence of lesions, and stained for ER and PR receptors using an immunocytochemical method. The immunoreactivity was scored semiquantitatively, incorporating both the intensity and distribution of specific staining of the receptors using a simplified histoscore (H-score). At the time of ovariohysterectomy, fluid had accumulated in the isolated section of the uterine horn distal to the point of biopsy; the volume was greater in the MPA-treated bitches. There was also evidence in some sections of histological changes in the endometrium. Variations in the expression of both ER and PR were seen between bitches, which may have been due to some not being in mid-metoestrus at the time of treatment. In general, ER scores were low after P4 and MPA treatment, but following ODB there was a significant (P<0.05) increase in ER expression in all parts of the endometrium. PR scores were zero in the glandular epithelium of all 12 bitches after P4, MPA and ODB treatment, whereas in the other parts of the endometrium they were generally moderate to high. Following treatment with ODB, PR generally increased in the three regions of the endometrium where PR were present. The study shows that ER and PR distribution and expression in the endometrium of bitches can be modified by P4, MPA and ODB, with evidence of individual variation.     

Alkaline phosphatases and steroid receptors in human breast cancer

Estrogen receptors (ER), progesterone receptors (PR) and alkaline phosphatases (AP) were measured in 150 tumors from patients who underwent mastectomy for primary breast cancer. The percentage of ER positive samples was inversely related to the AP activity ranging from 88.9% in low activity samples (less than 30 U/mg prot.) down to 30.6% in the high activity ones (greater than 400 U/mg prot.). When considering only ER positive samples, the ER content was inversely related to the AP activity. This could not be demonstrated for PR. Therefore, the authors suggest the hypothesis that in human breast cancer, the AP may play a role in the dephosphorylation of the ER molecule and in the consequent modulation of its binding capability.     

Immunohistochemical localisation of progesterone and oestrogen receptors at the placental interface in mares during early pregnancy

Previous reports documenting progesterone receptors (PR) and oestrogen receptors (ER) in the endometrium of early pregnant mares included specimens only up to Day 20 post ovulation. This study aimed to localise PR and ERα on equine feto-maternal tissues between Days 20 and 68 to encompass the period around fixation of the conceptus, development of the endometrial cups and attachment and initial interdigitation of the allantochorion. During early pregnancy mares had the same pattern of PR in the endometrium as that reported for other mammals; namely, a loss of PR from the endometrial epithelia but continued localisation in stromal cells. The spatial arrangement of ERα over the same time period showed cytoplasmic staining of endometrial epithelia and in the nuclei of occasional stromal cells. In the fetal tissues, no cells had PR although ERα was evident in some tissue compartments. No major change in localisation of either receptor was noted throughout the time period examined despite important changes occurring at the placental interface. Nevertheless, these steroid receptor molecules probably play important roles in the production of histotroph and growth factors by the endometrium which go on to stimulate differentiation and growth of the feto-maternal tissues.     

Distribution of estrogen and progesteron receptors in the uterus: an immunohistochemical study in the immature and adult pseudopregnant rabbit

Summary In order to clarify the distribution and content of estrogen (ER) and progesteron receptors (PR) under changing hormonal influences within the various cell populations of the uterus (glandular and luminal endometrial epithelium, stroma, myometrium), immunohistochemical determinations using specific monoclonal antibodies were made. To correlate the immunohistochemical findings with peripheral hormone levels and specific tasks of the endometrium, 17-estradiol and progesterone serum levels were measured and cell proliferation determined by use of BrdU-labelling-immunohistochemistry. At the subcellular level ER and PR were located exclusively in the cell nuclei of female rabbits, which were either immature and lacking any peripheral hormone levels or were pseudopregnant (d0–d8 p.hCG). In the immature rabbits a general faint ER and PR immunostaining was found. In addition to a general increase in ER and PR in all cell populations estrous rabbits (d0 p.hCG) showed a significant rise of ER in the epithelial cells and of PR in the myometrium. Within the epithelial cells and the myometrium the ER dropped heavily within a few days of pseudopregnancy. The PR, however, increased sharply during the first two days of pseudopregnancy and decreased gradually following d4 p.hCG. A close relationship was observed between the high PR content and the proliferation rate of the epithelial cells on d2 p.hCG. In spite of the more rapid decrease of ER compared with PR, the glandular epithelium retained positive immunostaining. In the stroma the ER and especially PR content did not change significantly during the course of pseudopregnancy suggesting that some of the well-known differentiation events in the luminal epithelium may be mediated by the stroma.     

ER和PRmRNAs在内异症子宫内膜表达的变化

目的 :探讨雌激素受体 (ER)和孕激素受体 (PR)在子宫内膜异位症 (内异症 )子宫内膜的表达。方法 :利用大鼠内异症动物模型 ,采用逆转录聚合酶链反应 (RT PCR)技术 ,检测子宫内膜ER和PRmRNAs的表达情况。结果 :内异症模型组大鼠异位内膜ER、PRmRNAs的表达低于在位内膜和对照组正常子宫内膜 ,与后两者比较差异有显著性意义 (P <0 .0 1) ;而模型组在位内膜ER、PRmRNAs的表达与正常对照组比较差异无显著性意义 (P >0 .0 5 )。内异症模型组异位内膜ER/PRmRNA比值大于在位内膜和正常子宫内膜ER/PRmRNA比值 (P <0 .0 1)。结论 :内异症大鼠异位内膜ERmRNA表达的相对增高在内异症的发生与发展中起着一定的作用。     

Effects of onapristone on postmenopausal endometrium

The progesterone antagonist mifepristone (RU486, Exelgyn) has been shown to exert a paradoxical agonist effect on postmenopausal endometrium. We conducted a study to investigate the effects of the 'pure' antiprogestin onapristone (ZK 98 299, Schering AG) on postmenopausal endometrium. Seventeen postmenopausal subjects (45-62 years), took 2 mg of oestradiol and either placebo, 1 mg onapristone or 10 mg of onapristone, daily for 56 days. An endometrial biopsy was performed during the final week of treatment and assessed for histology and immunohistochemistry for oestrogen receptors (ER), progesterone (PR), androgen receptors (AR) and the cell proliferation marker Ki 67. FSH fell in all 14 subjects who completed the study, consistent with the effect of oestradiol treatment. There was a dose-dependent additive effect of onapristone on suppression of gonadotrophins. All endometrial biopsies showed proliferative endometrium. A similar pattern and intensity of immunostaining of ER, PR and Ki 67 was observed in all groups, with positive immunoreactivity in both glands and stroma. AR immunostaining was observed in both glands and stroma from all subjects, but there was an increase in intensity of immunostaining within the glandular epithelium of women receiving 10 mg onapristone. The antiprogestin onapristone, in contrast to mifepristone, is not agonistic on postmenopausal endometrium and does not exert obvious antiproliferative effects. It does however cause a dose dependent suppression of FSH and LH release.     

Expression of estrogen receptors during growth of human pancreatic adenocarcinoma cells (Capan-1)-relationship with differentiation

Summary In steroid target tissues, the presence of the corresponding hormone receptors is indicative of hormone dependence. In an attempt to assess the possible role of steroid hormones in the mechanism of growth and/or differentiation of cancerous pancreatic duct cells, the expression of estrogen receptor (ERα) was evaluated in human cancerous pancreatic duct cells (Capan-1) maintained in culture. These cells were selected as they acquire progressively a high degree of differentiation during growth in culture. In the present study, we showed that Capan-1 cells during growth in steroid-free medium associate spontaneously, become polarized, and form duct-like structures, features that are indicative of a high degree of differentiation. Capan-1 cells were also found to express ERα and progesterone receptor (PR). Immunoenzymatic assay showed maximal expression of ERα (236 ± 55 fmol/mg protein) on the first day of the exponential growth phase, followed by a marked fall in expression (76.3%). At the onset of the stationary phase (Day 5), ERα levels were below 10 fmol/mg protein, becoming undetectable by Day 7. A similar time course was observed for PR: 18 ± 0.9 fmol/mg protein at the onset of the exponential growth phase and no expression during the stationary phase. Addition of estradiol to 1-d-old cultures resulted in a twofold increase in PR expression, suggesting an induction of PR expression by estrogen. Immunocytochemical analysis with anti-ERα-1D5 antibodies showed nuclear and cytoplasmic localization of ERα in Capan-1 cells in the first 24 h of culture followed by a progressive disappearance thereafter. We also showed that cellular multiplication was increased by estradiol and progesterone during the exponential growth phase, pointing to the involvement of steroid hormones in the proliferation of nonpolarized Capan-1 cells. These results indicate that the expression of ERα is linked to the state of differentiation of the cells and make Capan-1 cells a model of choice to study ER regulation in nontarget tissues.     

Cell-specific expression of estrogen-responsive genes in the uteri of cyclic, early pregnant and ovariectomized ewes

A single physiological dose of estradiol up-regulates estrogen receptor-alpha(ER), progesterone receptor (PR), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), c-fos, cyclophilin, and actin mRNAs in the endometrium of ovariectomized ewes. Therefore, we hypothesized that these genes would be up-regulated by the preovulatory surge of estrogen which occurs on the evening of Day 15 in the estrous cycle of sheep. ER and PR mRNA concentrations increased between Day 15 and Day 1 in cyclic ewes in most endometrial epithelial cells, while GAPDH mRNA increased in epithelial and stromal cells in the deep endometrium. Day 15 pregnant ewes had lower expression of ER, PR, GAPDH, cyclophilin and actin genes. For ER and GAPDH mRNAs, the greatest reduction occurred in the superficial endometrium. Ovariectomized ewes demonstrated concentrations of ER, PR, and GAPDH mRNAs that were similar to those in the cyclic ewes. While concentrations of c-fos mRNA did not differ between groups, those of cyclophilin and actin mRNAs were lower in the pregnant and ovariectomized ewes. In conclusion, ER, PR and GAPDH gene expression rose during estrus in endometrial cells with the highest ER gene expression and were repressed in pregnant ewes in superficial endometrial cells with the greatest PR gene expression.     

Monoclonal antibody characterization of progesterone receptors, estrogen receptors and the stress-responsive protein of 27 kDa (SRP27) in human uterine leiomyoma

Uterine leiomyoma occurs in one of every four or five women during their reproductive life. Its origin is unknown but it is accepted that estrogens play a significant role in its development. In order to learn more about the estrogen dependency of leiomyoma, the biochemical and immunological properties of two markers of estrogen response in target cells (the progesterone receptor (PR) and the stress-responsive protein of 27 kDa (SRP27)) were studied in leiomyoma. The ER (estrogen receptor) and PR content were determined by conventional DCC exchange assays. Specific anti-ER, anti-PR and anti-SRP27 monoclonal antibodies were used in immunoblots and immunohistochemical (IHC) studies. The binding properties of PR from cytosol of leiomyoma showed a Kd of 0.8-1.3 nM, which is in the range described for other human tissues. 80% of all studied leiomyoma contained PR, in a range of 805-2000 fmol/mg protein. The Kd for leiomyoma ER was 0.1-0.9 nM, and 84% of the samples were positive for ER. The PR of leiomyoma has the two A and B forms of 120 and 94 kDa, as shown in the immunoblot using the AB52 anti-PR monoclonal antibody. The IHC study revealed that the PR is concentrated in the cell nuclei, in the form of perinuclear bodies, with a homogeneous staining pattern from cell to cell. The leiomyoma fibres contain SRP27 in a higher concentration than the healthy myometrium. The leiomyoma SRP27 shows a typical doublet of 24 kDa and 27 kDa in immunoblot, the same as in MCF-7 cells. The IHC study revealed a high degree of organization of SRP27 in leiomyoma cells, suggesting that this protein may be part of the cytoskeleton. The results obtained show that human leiomyomas contain ER, PR and RSP27 with similar immunological and biochemical properties to those of other human tissues, including the MCF-7 breast cancer cell line.     

Distribution of estrogen and progesteron receptors in the uterus: an immunohistochemical study in the immature and adult pseudopregnant rabbit.

In order to clarify the distribution and content of estrogen (ER) and progesteron receptors (PR) under changing hormonal influences within the various cell populations of the uterus (glandular and luminal endometrial epithelium, stroma, myometrium), immunohistochemical determinations using specific monoclonal antibodies were made. To correlate the immunohistochemical findings with peripheral hormone levels and specific tasks of the endometrium, 17 beta-estradiol and progesterone serum levels were measured and cell proliferation determined by use of BrdU-labelling-immunohistochemistry. At the subcellular level ER and PR were located exclusively in the cell nuclei of female rabbits, which were either immature and lacking any peripheral hormone levels or were pseudopregnant (d0-d8 p.hCG). In the immature rabbits a general faint ER and PR immunostaining was found. In addition to a general increase in ER and PR in all cell populations estrous rabbits (d0 p.hCG) showed a significant rise of ER in the epithelial cells and of PR in the myometrium. Within the epithelial cells and the myometrium the ER dropped heavily within a few days of pseudopregnancy. The PR, however, increased sharply during the first two days of pseudopregnancy and decreased gradually following d4 p.hCG. A close relationship was observed between the high PR content and the proliferation rate of the epithelial cells on d2 p.hCG. In spite of the more rapid decrease of ER compared with PR, the glandular epithelium retained positive immunostaining. In the stroma the ER and especially PR content did not change significantly during the course of pseudopregnancy suggesting that some of the well-known differentiation events in the luminal epithelium may be mediated by the stroma.