Estrogen regulates the synthesis of epidermal growth factor in mouse uterine epithelial cells

Physiological coupling of growth factor and steroid receptor signaling pathways: estrogen receptor knockout mice lack estrogen-like response to epidermal growth factor

Past studies have shown that epidermal growth factor (EGF) is able to mimic the uterotropic effects of estrogen in the rodent. These studies have suggested a "cross-talk" model in which EGF receptor (EGF-R) signaling results in activation of nuclear estrogen receptor (ER) and its target genes in an estrogen-independent manner. Furthermore, in vitro studies have indicated the requirement for ER in this mechanism. To verify the requirement for ER in an in vivo system, EGF effects were studied in the uteri of ER knockout (ERKO) mice, which lack functional ER. The EGF-R levels, autophosphorylation, and c-fos induction were observed at equivalent levels in both genotypes indicating that removal of ER did not disrupt the EGF responses. Induction of DNA synthesis and the progesterone receptor gene in the uterus were measured after EGF treatment of both ERKO and wild-type animals. Wild-type mice showed increases of 4.3-fold in DNA synthesis, as well as an increase in PR mRNA after EGF treatment. However, these responses were absent in ERKO mice, confirming that the estrogen-like effects of EGF in the mouse uterus do indeed require the ER. These data conclusively demonstrate the coupling of EGF and ER signaling pathways in the rodent reproductive tract.

Effects of sex hormones on mesangial cell proliferation and collagen synthesis

In a variety of renal diseases, males progress at a more rapid rate and have a more fulminant course than females. This gender difference may be related to the direct effects of sex hormones on the cells of the kidney. To evaluate this hypothesis, we studied the effects of estrogens and testosterone on mesangial cell proliferation and collagen synthesis. At 48 hours, estradiol at 10 nM and 100 nM had a modest proliferative effect on cultured mesangial cells, as measured by 3H thymidine incorporation into DNA and direct cell counting. This estradiol effect was fully reversed by Tamoxifen (1 microM). Estradiol had no effect on cellular proliferation at 1 microM concentrations, but suppressed proliferation at 10 microM doses. Testosterone had a modest but statistically insignificant effect on proliferation at 10 nM and 100 nM concentrations but no effect at 1 microM or 10 microM. Neither estradiol nor testosterone at 10 microM affected total cellular protein accumulation. Estradiol at 1 microM and 10 microM, markedly suppressed total collagen synthesis as measured by 3H proline incorporation, and specifically suppressed the synthesis of collagen types I and IV, as measured by immunoprecipitation and gel electrophoresis. Testosterone did not affect collagen synthesis. Estradiol also reduced the steady state message for the alpha 2 chain of type I collagen, while testosterone had no effect. Neither estradiol nor testosterone affected the steady state message for TGF beta or EGF. The direct effects of estradiol on mesangial cell collagen generation may help explain the slower development of glomerulosclerosis in women and therefore the "protective" effect of female gender on the progression of renal disease.

Immunohistochemical studies on the expression and estrogen dependency of EGF and its receptor and C-fos proto-oncogene in the uterus and vagina of normal and neonatally estrogen-treated mice

BACKGROUND

The final target cell response to estrogen is dependent not only on the estrogen receptor, but also on autocrine/paracrine interactions with growth factors (e.g., EGF) and proto-oncogenes (e.g., c-fos). Because neonatal estrogen treatment results in permanent changes in the female mouse genital tract (permanent vaginal cornification, cervical adenosis and tumors, changed growth control mechanisms in uterus), it was of interest to study possible acute and permanent effects of such treatment on distribution and levels of EGF, its receptor (EGF-r), and c-fos and to relate such changes to morphological development and appearance of epithelial abnormalities.

METHODS

Immunohistochemical techniques using frozen sections from the uterus and vagina of neonatal and adult (ovariectomized, estradiol-treated) females, treated with olive oil or diethylstilbestrol in neonatal life.

RESULTS

A difference in stromal-epithelial distribution of EGF was demonstrated with respect to region studied (uterus, vagina) and age (neonatal, adult). EGF was localized mainly in the uterine stroma but in both vaginal epithelium and stroma (with a different pattern compared to uterus). In neonatal females, EGF occurred in both tissue components in both regions, and the distribution pattern was quite different from that in adult females. The EGF level was increased by estrogen in adult but not in neonatal females. EGF-r and c-fos occurred in both uterine epithelium and stroma and in the vaginal epithelium; levels and distribution pattern were affected by estrogen. Neonatal estrogen treatment increased the levels of uterine EGF and c-fos in adult life.

CONCLUSIONS

There are distinct developmental changes in the distribution and estrogen sensitivity of EGF. Only further studies can prove or disprove the association between the earlier reported disturbed growth control mechanisms in the uterus of adult but neonatally estrogen-treated females and the increased levels of uterine EGF and c-fos. The present results do not seem to explain mechanisms involved in the origin of neonatally estrogen-induced cervicovaginal epithelial abnormalities, nor do they explain the earlier described difference in estrogen-induced proliferative response between the uterine cervix and uterus proper.

Estrogen induces expression of c-fos and c-jun via activation of protein kinase C in an endometrial cancer cell line and fibroblasts derived from human uterine endometrium

Endometrial fibroblasts derived from uterine endometrium as controls and endometrial cancer cell lines (Ishikawa and HHUA cells) were analyzed for the induction manner of c-fos and c-jun transcripts in endometrial cancers, some of which are estrogen-dependent in growth. Estrogen increased c-fos expression and protein kinase C (PKC) activity in fibroblasts and Ishikawa cells, but not in HHUA cells. Progesterone diminished c-fos and c-jun expression and PKC activity induced by estradiol in the fibroblasts, but not in Ishikawa cells, which persistently overexpressed c-fos and c-jun. In these cells, 12-0-tetra-decanoylphorbol-13-acetate (TPA) increased c-fos and c-jun expression as did estradiol. Pretreatment with 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7) abolished estrogen-inducible over-expression of c-fos and c-jun. The combination of both estradiol and TPA at maximum effective concentration exerted no additive and synergistic effect on induction of c-fos and c-jun expression. In conclusion, persistent activation of PKC might lead to overexpression of c-fos and c-jun in some endometrial cancers with an estrogen predominant milieu, which might be, at least in part, associated with the transformation or growth potential.

A phorbol ester that activates protein kinase C mimics the action of estradiol or epidermal growth factor for initiating embryo implantation in the delayed implanting hypophysectomized rat

In rodents an action of estrogen is required for the initiation of implantation of the blastocyst into the endometrium of a progesterone-primed uterus. Thus removal of endogenous estrogen, either directly by ovariectomy or indirectly by hypophysectomy, prevents implantation in the pregnant rat. In the present study, delayed implanting hypophysectomized progesterone-primed rats were used to test the efficacy of cyclic adenosine 3',5'-monophosphate (cAMP), epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I), which are agents that have been shown to mimic some uterine actions of estradiol, to initiate implantation. In confirmation of previous studies, EGF injected into the uterine lumen plus intravenously was effective at initiating implantation in all animals. IGF-I showed no such activity in this model system. Cyclic AMP, increased via direct activation of adenylyl cyclase by forskolin, or administration of sodium dibutyryl cAMP, did not initiate implantation. However, a ligand for protein kinase C (PKC), phorbol 12-myristate 13-acetate, was effective in augmenting the action of intrauterine EGF, or forskolin, for initiation of implantation. A phorbol ester that does not activate PKC was ineffective. The results provide circumstantial evidence for the requirement of PKC activity in the implantation initiating action of estrogens.

Differential gene regulation by estrogen and progesterone in the primate endometrium

During the shift from a proliferative to a secretory endometrium in the rhesus menstrual cycle, progesterone action causes massive metabolic and structural remodelling. In order to identify genes whose expression is potentially important for the change from estrogen (E) to progesterone (P) dominance we have initiated a study of specific gene regulation using semiquantitative, reverse transcription polymerase chain reaction (RT-PCR). PolyA+ RNA was isolated from both E-dominant (days 9-13 of artificial menstrual cycles [AMCs]) and P-dominant (days 21-23) rhesus monkey endometria. The two pools of mRNA were converted to cDNA, end-ligated to double-stranded oligonucleotide adaptors and amplified by PCR using an adaptor-complementary primer. This procedure resulted in the production of E- and PcDNA template populations for cDNA-specific screening and comparative quantitation by PCR. Initial analysis showed that placental protein 14 (PP14) was P-dependent and human complement 3 (HC3) was up-regulated in E-dominant tissue, whereas the housekeeping genes B-actin and glyceraldehyde-3-phosphate dehydrogenase (G-3-PDH) were expressed at equivalent levels under E and P dominance. Expression of the E receptor (ER), P receptor (PR), epidermal growth factor receptor (EGFR) and insulin-like growth factor (IGF-I) was equivalent under E or P dominance. Expression of epidermal growth factor (EGF) and retinoblastoma (RB) was down-regulated in P-dominant tissue. Conversely IGF-1 receptor (IGF-1-R), transforming growth factor-beta 2 (TGFB-2), TGFB-2 receptor (TGFB-2-R), 17 beta-hydroxysteroid dehydrogenase (17-B-HSD) and leukemia inhibitory factor (LIF) levels were up-regulated in PcDNA. Among these factors, PP14, LIF, IGF-1-R TGFB-2 and 17-B-HSD were also detectable in PCR in a P-dependent cDNA library isolated by subtractive hybridization. These data provide evidence for hormonal regulation of specific gene products that may play important roles in the normal maturation of the primate endometrium in preparation for implantation.

Estrogen induces c-Ha-ras expression via activation of tyrosine kinase in uterine endometrial fibroblasts and cancer cells

Endometrial fibroblasts derived from uterine endometrium as controls and endometrial cancer cells (Ishikawa and HHUA cells) were used to analyze the manner of induction of c-Ha-ras transcripts in endometrial cancers, some of which are estrogen-dependent in growth. Estrogen increased c-Ha-ras expression and tyrosine kinase (TK) activity in fibroblast and Ishikawa cells, but not in HHUA cells. Progesterone diminished c-Ha-ras expression and tyrosine kinase (TK) activity induced by estradiol in the fibroblasts, but not in Ishikawa cells, which persistently overexpressed c-Ha-ras. In these cells, epidermal growth factor (EGF) increased c-Ha-ras expression as did estradiol. Pretreatment with tyrphostin, an inhibitor of TK, abolished estrogen-inducible overexpression of c-Ha-ras. The combination of both estradiol and EGF at maximum effective concentration exerted no additive or synergistic effect on induction of c-Ha-ras expression. In conclusion, persistent activation of TK might lead to overexpression of c-Ha-ras in some endometrial cancer cells under estrogen predominant milieu, which might be associated with the transformation or growth potential.

Dexamethasone attenuates the estradiol-induced increase of IGF-I mRNA in the rat uterus

In recent years growth factors, e.g. insulin-like growth factor-I (IGF-I), transforming growth factor-alpha (TGF-alpha) and epidermal growth factor (EGF), have been considered as mediators of estradiol-stimulated growth in the uterus. In the liver, dexamethasone (Dex) has been shown to inhibit the IGF-I mRNA increase induced by growth hormone (GH). In the present study the influence of Dex on estradiol-stimulated induction of uterine IGF-I mRNA was examined. The concentration of IGF-I mRNA in the uterus and liver was monitored, as well as the levels of ER mRNA and estrogen receptor (ER). Since it has been previously shown that the maximal induction of uterine IGF-I mRNA after estradiol (E2) stimulation occurs after 21-24 h, Dex was administered to ovariectomized (ovx) rats 3 h before an E2 injection and 24 h before sacrifice. There was a significant decrease in IGF-I mRNA in the Dex+E2 treated rats compared to the rats given E2 only. In both groups an increase was seen compared to the level in the ovx control group. The uterine ER mRNA levels in E2 and Dex+E2 treated animals were significantly elevated compared to the ovx control. There were no significant changes in uterine ER content after hormone treatment compared to the level in ovx control rats. In the liver no effects on IGF-I mRNA were detected. Hepatic ER mRNA was significantly increased in the E2 treated group, compared to both the ovx control group and the animals that received Dex+E2. The hepatic ER level was also increased in the E2 treated group compared to the ovx control and the group which received Dex+E2. In conclusion, Dex does attenuate the estrogen-induced uterine IGF-I mRNA increase in ovx rats. In addition to this, Dex was found to inhibit the estrogen-induced increase in ER and ER mRNA in the liver of ovx rats.

Epidermal growth factor receptor function in early mammalian development

We review here the data indicating a role for epidermal growth factor receptor (EGF receptor) signalling in early mouse development. Embryonic development of the metazoan embryo generally begins with the formation of a cystic structure and epithelial layers that subsequently form anlagen of the definitive body parts and organs. For the mammalian embryo, this cystic structure is a blastocyst whose wall consists of trophectoderm, the first epithelium to develop during mammalian embryogenesis. The onset of expression and function of EGF receptors is coincident with the onset of trophectoderm development. Modulating EGF receptor expression and function modulates trophectoderm differentiation, leading to the hypothesis that functional EGF receptors participate in the induction of trophectoderm development and perhaps of other embryonic epithelial derivatives such as nervous tissues.

Oestrogen induces c-Ha-ras expression in the fibroblasts derived from human uterine endometrium

In this preliminary study, fibroblasts derived from uterine endometrium as a substitute for normal endometrial stroma were used to analyse the stromal role in uterine endometrium, which depends on oestrogen for growth. C-Ha-ras expression and tyrosine kinase (TK) activity in the fibroblasts were increased by oestradiol, and the increase was diminished by progesterone. Epidermal growth factor (EGF), an activator of TK, also increased c-Ha-ras expression. The combination of both oestradiol and EGF at maximum effective concentration exerted no additive and synergistic effect on induction of c-Has-ras expression. Pretreatment with tyrphostin, an inhibitor of TK, abolished the oestrogen-inducible expression of c-Ha-ras. Oestrogen might lead to rapid induction of c-Ha-ras expression in endometrial stroma, at least in part, via the activation of TK for the early stages of oestrogen dependent growth in endometrium.

Steroid regulation of parathyroid hormone-related protein expression and action in the rat uterus

The gene encoding parathyroid hormone-related protein (PTHrP), an autocrine/paracrine inhibitor of vascular and nonvascular smooth muscle contractility, is regulated by hormonal steroids including estrogens (E2), 1,25-dihydroxy vitamin D (Vit D3) and glucocorticoids. While E2 increases PTHrP gene expression, Vit D3 and glucocorticoids inhibit transcriptional activity of this gene. In the uterus of ovariectomized rats, E2-treatment increases both PTHrP mRNA levels and smooth muscle sensitivity to the action of PTHrP(1-34). To examine the action(s) of Vit D3 and glucocorticoids on these parameters, OVX rats were treated with E2, Vit D3 or the synthetic glucocorticoid, dexamethasone (Dex), alone, or with E2 following a 1 h pretreatment with Vit D3 or Dex. PTHrP and PTH/PTHrP receptor mRNA were measured by blot hybridization analysis of RNA prepared from uteri collected 2, 4 and 24 h after treatment. Uterine horns were used to measure the effect of the steroids on the ability of PTHrP(1-34) to inhibit spontaneous myometrial contraction. When E2, Vit D3 and Dex were given alone, only E2 altered PTHrP mRNA levels in the uterus, however, a 1 h pretreatment with Dex but not Vit D3 markedly diminished this effect of E2. The temporal decline in uterine PTH/PTHrP receptor mRNA levels measured 2 and 4 h after E2 treatment inversely correlated to changes in sensitivity of the tissue to PTHrP(1-34) measured at 24 h after E2 administration. In comparison to E2 alone, treatment with Vit D3 and E2 augmented the uterine responsiveness to PTHrP(1-34) while pretreatment with Dex (1 mg/kg) and E2 decreased this response. These data indicate that in the uterus, Dex opposes the positive effect of E2 on PTHrP gene activity and differentially modulates the action of PTHrP on myometrial tone. Moreover, elevations in the circulating levels of cortisol at term may serve to decrease both the uterine expression of PTHrP and the local action of PTHrP on the myometrium prior to parturition, therefore promoting myometrial contraction associated with labor.

The impact of gender on the progression of chronic renal disease

Observations in experimental animals and in humans have shown that the rate of progression of renal disease is influenced by gender. Deterioration of renal function in patients with chronic renal disease is more rapid in men than in women, independent of differences in blood pressure or serum cholesterol levels. In addition to genetically determined differences between the sexes in renal structure and function, sex hormones may directly influence many of the processes implicated in the pathogenesis of renal disease progression. Potential mechanisms include receptor-mediated effects of sex hormones on glomerular hemodynamics and mesangial cell proliferation and matrix accumulation as well as effects on the synthesis and release of cytokines, vasoactive agents, and growth factors. In addition, estrogens may exert potent antioxidant actions in the mesangial microenvironment, which may contribute to the protective effect of female gender.

Proteinase expression in early mouse embryos is regulated by leukaemia inhibitory factor and epidermal growth factor

Several proteinases from different multigene families have been implicated in the uterine invasion required for establishment of pregnancy in some mammals. In this study, the expression of matrix metalloproteinase gelatinase B (MMP-9), urokinase-type plasminogen activator (uPA) and their inhibitors was investigated during early mouse embryo development. Transcripts for tissue inhibitors of metalloproteinases (TIMP-1,-2,-3) and uPA receptor were detected throughout pre- and peri-implantation development whilst MMP-9 and uPA mRNAs were first detected in peri-implantation blastocysts associated with the invasive phase of implantation. Through use of in situ hybridization, it was shown that MMP-9 transcripts were strongly expressed in the network of trophoblast giant cells at the periphery of implanting 7.5 day embryos and TIMP-3 transcripts were strongly expressed in the decidua immediately adjacent to the implanting embryo. uPA transcripts were preferentially expressed in the ectoplacental cone and its derivatives. Because these proteinases are regulated by growth factors and cytokines in other tissues, the effect of leukaemia inhibitory factor (LIF) and epidermal growth factor (EGF) on their activity was investigated. Both LIF and EGF, like the proteinases, have been implicated in peri-implantation development. Blastocysts collected on day 4 of pregnancy were cultured 2 days in TCM 199 + 10% fetal bovine serum to allow outgrowth followed by 24 hour culture in defined media containing either LIF or EGF. Conditioned media were assayed for uPA activity by a chromogenic assay and MMP activity by gelatin zymography. Both LIF and EGF stimulated uPA and MMP-9 activity in blastocyst outgrowths after 3 days of culture (day 7). Proteinase activity was assayed again at the 5th to 6th day of culture (day 9 to 10). EGF was found to have no effect whereas LIF decreased production of both proteinases. These results demonstrate that proteinase activity in early embryos can be regulated by growth factors and cytokines during the implantation process and, in particular, they demonstrate the possible involvement of LIF in establishment of the correct temporal programme of proteinase expression.

Expression of pituitary peptide 23 in the rat uterus: regulation by estradiol

Peptide 23 was first identified in pituitary cell conditioned medium as a secreted protein which was regulated in a similar fashion to growth hormone. It was subsequently found to be a member of the C-type lectin gene superfamily and identical to pancreatis associated protein (PAP). It is widely expressed in the gastrointestinal tract. Our present study demonstrates that peptide 23 gene is also expressed in the uterus. Peptide 23/PAP mRNA was at highest levels during estrus and was not detectable in the immature rat uterus. A single injection of 17 beta-estradiol resulted in a transient induction of peptide 23/PAP mRNA in ovariectomized rats whereas a sustained induction was seen with diethylstilbestrol implants. In situ hybridization localized peptide 23/PAP mRNA to the luminal epithelial cells. During gestation, peptide 23/PAP mRNA was detected only in the uterine samples from day 12 to 18 of pregnancy with maximal expression on day 12. Peptide 23 expression was confined to the uterus itself and not expressed in either the decidua or the fetal tissues. PSP/reg, another closely related member of the C-lectin gene family was not expressed in any of these uterine tissues. These results indicate that estrogen may act as a physiological regulator of peptide 23 in the uterus and suggests that this protein may have some role in estrogen action.

EGF, TGF-alpha and EGFR expression in human preimplantation embryos

Epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha) through their common receptor, epidermal growth factor receptor (EGFR) are known to enhance mitogenesis, development and implantation in several species. In the mouse, co-culture of grouped embryos in microdrops increases the cell number and proportion developing to the blastocyst stage. A similar effect is observed with culture of single embryos in medium supplemented with EGF or TGF-alpha highlighting their embryotrophic effects. To study the role of EGF, TGF-alpha and EGFR in early human development, two methods applicable for analysis of expression at the single embryo level have been employed. In the first method, reverse transcription-polymerase chain reaction has been used to examine the presence of transcripts. Following reverse transcription, strategically designed nested primers, optimised for specificity, were used for amplification from the cDNA equivalent of a single embryo. The products were then verified by restriction enzyme digestion and sequence analysis. In the second method, immunocytochemistry has been used to colocalise the expressed proteins. Individual embryos were paraffin embedded and serial sectioned, allowing adjacent sections to be examined with different antibodies and controls. Monoclonal TGF-alpha and polyclonal EGF and EGFR primary antibodies were used. Staining was performed by peroxidase-conjugated avidin-biotin immunocytochemistry with the appropriate controls. The combination of these two methods can potentially be used for simultaneous analysis of several growth factors and/or their receptors in the same human embryos. Transcripts for EGF, TGF-alpha and EGFR were detected in unfertilized oocytes and embryos between 8-cell and blastocyst stages on day 3 to 6 post-insemination.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of insulin-like growth factor binding proteins (IGFBPs) by human endometrial stromal cell is stimulated by the presence of embryos

PURPOSE

To identify IGFBPs among endometrial secretory products and study their role in implantation and early embryo development.

METHODS

Two-cell CB6F1 mouse embryos were cultured alone or with human endometrial stromal cells in RPMI 1640 plus 10% fetal calf serum (FCS) with or without addition of IGF-I (20 micrograms/ml), IGF receptor antibody (0.1 microgram/ml), progesterone (P) (20 ng/ml) and relaxin (R) (20 micrograms/ml). On the designated day, the medium was changed to protein-free RPMI and incubated for 16 h. Both conditioned medium and conditioned protein-free medium were then collected for protein analysis and immunoradiometric assay. Cells were fixed with 4% paraformaldehyde for immunohistochemical staining.

RESULTS

IGFBP1 (31 kDa), IGFBP2 (36 kDa), IGFBP3 (45 kDa and 50 kDa) and an unknown IGFBP (25 kDa) were identified in conditioned medium of human endometrial stromal cells cultured alone or cocultured with mouse embryos. Secretion of IGFBPs by endometrial stromal cells was stimulated in the presence of mouse embryos as well as by P and R. IGFBP3 appears to be more responsive to embryonic signals. On the other hand, the secretion of IGFBP1 was greatly stimulated by P and R. Immunolocalization revealed that all three BPs were present in both embryonic and endometrial cells and their immunological staining was heavily increased by P and R.

CONCLUSIONS

Endometrial stromal cells were able to synthesize and secrete IGFBPs to modify IGF action on embryo development. Secretion of IGFBPs was stimulated by embryonic signals and was hormonally dependent. The fact that IGFBP3 was more responsive to embryonic signals suggests that it may be important in early implantation. On the other hand, IGFBP1 production was highly responsive to both P and R, suggesting that it may be important throughout pregnancy. In addition, the fact that IGFBPs were located in endometrial and embryonic cells may suggest that these secretory products have autocrine and/or paracrine effects on both types of cells.

The role of growth factors in preimplantation development

It has become clear that the mammalian embryo participates in a complex dialogue with the maternal physiology. The language of the dialogue is growth factor signalling. The embryo expresses receptors for insulin, IGFs, GH, EGF and cytokines including LIF, and CSFs; whilst ligands are secreted by the supporting tissues of the oviduct and uterus, and in some cases, the embryo itself. In the preimplantation period when the embryo is travelling to the uterus and passing through its first differentiation, these ligands affect embryonic physiology, apparently in ways that optimise developmental potential and synchronise embryonic and maternal physiologies. It is not yet clear in most cases whether this is by autocrine, paracrine or endocrine mode. In the crucial peri-implantation phase the embryo is preparing to invade the maternal system for which extensive uterine remodelling is necessary. A model is proposed in which a cascade of growth factor activities, orchestrated by the ovarian steroid patterns, choreographs the biochemical players (ECM proteinases and their inhibitors) which initiate this activity.

Myometrial expression of mRNA encoding epidermal growth factor receptor (EGFR) throughout the menstrual cycle

PROBLEM

To investigate the quantitative changes in expression of EGFR mRNA in the myometrium throughout the menstrual cycle.

METHOD

Myometrium was collected at hysterectomy from 27 women with a history of regular cycles. Total RNA (20 micrograms) was isolated and analyzed by Northern blot using a human EGF-R specific 32P-labeled cDNA probe. The hybridization signals were quantified by densitometry, standardized, and reported in densitometry signal units (DSU). Endometrial specimens from the same uteri were simultaneously evaluated for histologic dating of menstrual cycle day. EGFR gene expression in endometrium was previously reported. Statistical significance of the differences in myometrial gene expression between menstrual phases was evaluated by student's t test.

RESULTS

EGFR mRNA was expressed in all myometrial tissues tested. Levels were higher in the late proliferative phase than in all other phases (P < .05). Women over 40 years old had lower proliferative phase expression than younger women.

CONCLUSION

This data suggests that myometrial EGFR mRNA expression varies in association with the histologic phases of the normal menstrual cycle, and may be affected by aging, even when cycles occur at regular intervals.

Epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor localization in the baboon (Papio anubis) oviduct during steroid treatment and the menstrual cycle

OBJECTIVES

Polypeptide growth factors may modulate the actions of estrogen (E2) and progesterone (P) in reproductive tissues in an autocrine/paracrine manner. The objective of this study was to determine whether the baboon oviduct contains epidermal growth factor (EGF), transforming growth factor-alpha (TGF alpha), and EGF receptor (EGF-R) and whether changes in their expression are correlated with various hormonal states.

METHODS

Oviductal tissue was obtained from adult female baboons (Papio anubis) after oophorectomy and steroid treatment, and during the menstrual cycle. Ampullary regions were fixed in Bouin's fixative and embedded in paraffin for immunocytochemistry using rabbit polyclonal antibodies against EGF and EGF-R, and mouse monoclonal antibody against TGF alpha.

RESULTS

Both EGF and EGF-R were present in all tissue compartments (most strongly in the epithelium, followed by smooth muscle and stroma) at all reproductive stages and showed similar staining patterns. However, the most intense immunoreactive product was found in the tissue obtained from the E2-treated and late follicular phase animals. At this time, intense staining was present in the apical regions of the mature ciliated cells, whereas the stain was dispersed uniformly over the cytoplasm of all other cell types. Immunoreactive TGF alpha was limited primarily to the nonciliated epithelial cells, and staining was most intense in the E2-treated and late follicular phase tissues. Transforming growth factor-alpha formed intense perinuclear deposits in the mature secretory cells, an area that corresponds to the Golgi region. No immunoreactive product was observed for any of these proteins when preimmune serum was substituted for the primary antibody or when the primary antibody was preabsorbed with antigen.

CONCLUSION

In summary, EGF, TGF alpha, and EGF-R are present in the ampulla of the baboon oviduct. Moreover, the localization and intensity of immunoreactive product are dependent on cell type and hormonal state. These data are consistent with the concept that EGF, TGF alpha, and EGF-R may be regulated by E2 and P and thus may play a role in cell differentiation and function. In addition, the specific localization of TGF alpha suggests that this growth factor may be synthesized for release from the secretory cells and thus may also function as a modulator of gamete/embryo viability and development.

Human trophoblast invasion. Autocrine control and paracrine modulation

Development of the human placenta involves rapid invasion of the uterine wall by fetal trophoblasts, a process with certain similarities to tumor cell invasion. Unlike tumor invasion, however, this unique interaction between genetically dissimilar trophoblast and uterine cells is closely regulated and limited both temporally and spatially by mechanisms that are largely unknown. We have used a combination of two experimental approaches to study this process: immunolocalization using tissue sections to investigate trophoblast invasion in vivo, and a cell culture model that allows manipulation of the invasion process in vitro. The results show that invading trophoblasts express activated forms of metalloproteinases, adhesion molecules and the novel class I histocompatibility antigen, HLA-G, in a highly regulated manner during invasion. The behavior of cytotrophoblasts in vitro, removed from the influences of uterine cells, closely parallels their behavior in vivo, suggesting the existence of autocrine control mechanisms. However, studies examining the effect of growth factors and cytokines on trophoblast invasion suggest that molecules of uterine origin can modify this process. Thus, we hypothesize that the intrinsic invasiveness of these cells is controlled, at least in part, by the specialized environment of the uterus. Future studies will concentrate on identifying these factors and the specific trophoblast functions they modify.

Epidermal growth factor--induced implantation and decidualization in the rat

Effects of epidermal growth factor (EGF) on blastocyst implantation and experimentally-induced decidualization were examined in the rat. Intraluminal injection of EGF into each uterine horn induced implantation in the ovariectomized progesterone-treated delayed implanting rat in a dose-dependent manner. This induction was inhibited by indomethacin, an inhibitor of prostaglandin synthesis. Intraluminal injection of EGF on day 5 of pseudopregnancy elicited a greater decidual response when compared to the vehicle-injected contralateral uterine horn. These results suggest that EGF may play important roles in the process of implantation and decidualization in the rat.

Heparin-binding EGF-like growth factor gene is induced in the mouse uterus temporally by the blastocyst solely at the site of its apposition: a possible ligand for interaction with blastocyst EGF-receptor in implantation

Heparin-binding EGF-like growth factor (HB-EGF) is a newly discovered member of the EGF family of growth factors. HB-EGF can bind to two loci on cell surfaces, heparan sulphate proteoglycans and EGF-receptor (EGF-R), and either one or both of these interactions could play a role in cell-cell interactions. In the rodent, increased endometrial vascular permeability at the site of blastocyst apposition is considered to be an earliest discernible prerequisite event in the process of implantation and this event coincides with the initial attachment reaction between the blastocyst trophectoderm and uterine luminal epithelium. This investigation demonstrates that the HB-EGF gene is expressed in the mouse uterine luminal epithelium surrounding the blastocyst 6–7 hours before the attachment reaction that occurs at 2200–2300 hours on day 4 of pregnancy. It was further demonstrated that this gene is not expressed in the luminal epithelium at the site of the blastocyst apposition during the progesterone-maintained delayed implantation, but is readily induced in the luminal epithelium surrounding an activated blastocyst after termination of the delay by an estrogen injection. In vitro studies showed that HB-EGF induced blastocyst EGF-R autophosphorylation, and promoted blastocyst growth, zona-hatching and trophoblast outgrowth. These results suggest possible interactions between the uterine HB-EGF and blastocyst EGF-R very early in the process of implantation, earlier than any other embryo-uterine interactions defined to date at the molecular level.

Progesterone-dependent expression of keratinocyte growth factor mRNA in stromal cells of the primate endometrium: keratinocyte growth factor as a progestomedin

In vitro studies have shown that keratinocyte growth factor (KGF, also known as FGF-7) is secreted by fibroblasts and is mitogenic specifically for epithelial cells. Therefore, KGF may be an important paracrine mediator of epithelial cell proliferation in vivo. Because stromal cells are thought to influence glandular proliferation in the primate endometrium, we investigated the hormonal regulation and cellular localization of KGF mRNA expression in the rhesus monkey uterus. Tissues were obtained both from naturally cycling monkeys in the follicular and luteal phases of the cycle, and from spayed monkeys that were either untreated or treated with estradiol (E2) alone, E2 followed by progesterone (P), E2 plus P, or E2 plus P plus an antiprogestin (RU 486). Northern blot analysis of total RNA with 32P-labeled probes revealed that the level of KGF mRNA in the endometrium was 70-100-fold greater in the luteal phase or after P treatment than in untreated, E2-treated, or follicular phase animals. Northern analysis also showed that KGF mRNA was present in the myometrium but was unaffected by hormonal state. RU 486 treatment prevented the P-induced elevation of endometrial KGF mRNA. P-dependent elevation of endometrial KGF expression was confirmed by measurement of KGF protein in tissue extracts using a two-site enzyme-linked immunosorbent assay. In situ hybridization with nonradioactive digoxigenin-labeled cDNA probes revealed that the KGF mRNA signal, which was present only in stromal and smooth muscle cells, was substantially increased by P primarily in the stromal cells located in the basalis region. Smooth muscle cells in the myometrium and the walls of the spiral arteries also expressed KGF mRNA, but the degree of this expression did not differ with hormonal state. P treatment led to increased proliferation in the glandular epithelium of the basalis region and to extensive growth of the spiral arteries. We conclude that the P-dependent increase in endometrial KGF resulted from a dual action of P: (a) a P-dependent induction of KGF expression in stromal cells, especially those in the basalis (zones III and IV), and (b) a P-dependent increase in the number of KGF-positive vascular smooth muscle cells caused by the proliferation of the spiral arteries. KGF is one of the first examples in primates of a P-induced, stromally derived growth factor that might function as a progestomedin.

Endometrial secretory proteins enhance early embryo development

PURPOSE

To evaluate the role of endometrial stromal cells and their secretory proteins in early embryo development, two-celled CB6F1 mouse embryos were cultured alone or cocultured with human endometrial stromal cells in various culture conditions.

RESULTS

The percentage of embryo blastocyst formation, hatching, and outgrowth was significantly greater in (1) coculture with endometrial stromal cells than in a cell-free control when both coculture and control were carried out in protein-free medium or in RPMI 1640 plus 10% fetal calf serum; (2) coculture with hormone (i.e., progesterone plus relaxin)-treated cells than in coculture with hormone-nontreated cells; and (3) media supplemented with isolated endometrial secretory proteins than in media supplemented with BSA (0.35%). Embryo development was not found to be significantly different in coculture and in media supplemented with endometrial secretory protein.

CONCLUSION

Our data provides credence to the theory that endometrial stromal cells enhance embryo development by secreting specific proteins that are beneficial to embryo growth in vitro.

Expression of transforming growth factor-beta 1 messenger ribonucleic acid and the modulation of deoxyribonucleic acid synthesis by transforming growth factor-beta 1 in human endometrial cells

OBJECTIVE

The purpose of this study was (1) to evaluate the potential sites of transforming growth factor-beta 1 synthesis in human endometrium by analyzing separated endometrial glands and stromal cells for transforming growth factor-beta 1 messenger ribonucleic acid by Northern analysis of total ribonucleic acid and (2) to investigate the effects of transforming growth factor-beta 1 on deoxyribonucleic acid synthesis in endometrial epithelial and stromal cells in culture.

STUDY DESIGN

Endometrial glands and stroma from proliferative and secretory endometrium were isolated after collagenase treatment of endometrial tissue minces and were analyzed for transforming growth factor-beta 1 messenger ribonucleic acid by Northern analysis. We studied the effects of estradiol-17 beta and transforming growth factor-beta 1 on deoxyribonucleic acid synthesis in endometrial epithelium and transforming growth factor-beta 1 on stromal cells in culture by evaluating tritiated thymidine incorporation into trichloroacetic acid-precipitable material.

RESULTS

Transforming growth factor-beta 1 messenger ribonucleic acid was detected for Northern analysis in separated endometrial stromal cells in levels that were greatest during the secretory phase and in greater levels than in epithelial cells from that same tissue. Transforming growth factor-beta 1 messenger ribonucleic acid in glandular epithelium in culture was not increased to detectable levels by treatment with transforming growth factor-beta 1. Deoxyribonucleic acid synthesis in endometrial glandular epithelium was inhibited by transforming growth factor-beta 1, but transforming growth factor-beta 1 stimulated deoxyribonucleic acid synthesis in endometrial stromal cells in culture. After treatment for 5 days with estradiol-17 beta (10(-8) mol/L), deoxyribonucleic acid synthesis in endometrial glands in culture was decreased by 40%. Transforming growth factor-beta 1 (1 ng/ml) did not alter this effect of estradiol-17 beta on deoxyribonucleic acid synthesis.

CONCLUSIONS

Transforming growth factor-beta 1 acts to decrease deoxyribonucleic acid synthesis in epithelial cells and to increase it in stromal cells isolated from human endometrium and maintained in monolayer culture. Transforming growth factor-beta 1, potentially of stromal cell origin, could participate in the regulation of endometrial cell proliferation and differentiation in vivo.

Tenascin is induced at implantation sites in the mouse uterus and interferes with epithelial cell adhesion

Expression of tenascin, an extracellular matrix protein associated with morphogenetic events and altered states of cellular adhesion, was examined in mouse uterus during the peri-implantation period. A uniform low level expression of tenascin was detected in stromal extracellular matrix during the estrous cycle and days 1 through 4 of early pregnancy. During the period of blastocyst attachment (day 4.5), an intense deposition of tenascin fibrils was located in the extracellular matrix of stroma immediately subjacent to the uterine epithelium surrounding the attaching blastocyst. This localized intensity of tenascin expression was both spatially and temporally restricted. By day 5.5, differentiation of stroma in the immediate area around the embryo to form the primary decidual zone was accompanied by a reduced amount of tenascin expression in the form of fragmented fibrils. Tenascin also could be induced by an artificial stimulus in uterine stroma of mice that had been hormonally prepared for implantation. The ability of artificial stimuli to induce tenascin expression suggested that the tenascin-inducing signals were derived from uterine cells, presumably lumenal epithelium, rather than embryonic cells. Consistent with this, conditioned medium from primary cultures of uterine epithelium was found to induce tenascin expression (2- to 4-fold) in isolated uterine stroma. Artificial stimuli generated a temporal pattern of tenascin expression similar to that observed during early pregnancy; however, in the artificially induced model, tenascin was induced in stroma immediately subjacent to lumenal epithelium along the entire length of the uterus. Purified tenascin and a recombinant tenascin fragment consisting of alternatively spliced fibronectin type III repeats, interfered with maintenance of uterine epithelial cell adhesion to Matrigel. In contrast, other recombinant tenascin fragments or fibronectin had no effect in this regard. Tenascin had no effect on adhesion of uterine stroma. Collectively, these results suggest that stimulation of TN expression in stromal extracellular matrix in vivo occurs via hormonally regulated, epithelial-mesenchymal interactions and serves as an early marker for uterine receptivity and the attachment phase of implantation. Furthermore, tenascin may facilitate embryo penetration by disrupting uterine epithelial cell adhesion to underlying basal lamina.

Luteal maintenance during early pregnancy in the pig: role for prostaglandin E2

We previously demonstrated that prostaglandin E2 (PGE) directly inhibits prostaglandin F2 alpha (PGF)-induced regression of individual pig corpora lutea (CL) in a dose dependent manner. The present experiments were conducted to 1) characterize and compare uterine secretion of PGE and PGF during the estrous cycle and early pregnancy and 2) evaluate the local effect of the conceptus on uterine prostaglandin secretion and associated CL function in unilaterally pregnant pigs. In Experiment 1, utero-ovarian venous blood samples were collected from two nonpregnant and two pregnant gilts at 3-h intervals from day 10 through 16 (first day of estrus or mating = day 0) for quantitation of uterine PGE and PGF secretion. In Experiment 2, gilts (n = 4) were made unilaterally pregnant on day 2, and utero-ovarian venous catheters were placed bilaterally to determine if differences in PGE and/or PGF secretion might account for the known luteotrophic/antiluteolytic effect of the gravid uterine horn on the CL of the ipsilateral ovary. During the estrous cycle (Experiment 1), pulsatile secretion of PGF increased markedly on day 13 and continued to increase through day 16. PGE secretion also increased from day 13 to 16 of the estrous cycle; however, concentrations of PGE remained at least 3-fold lower than those of PGF. In contrast to changes in non-mated gilts, prostaglandin secretion in mated gilts peaked earlier (day 11-12), with PGE predominating. Thereafter, both PGE and PGF secretion declined to basal levels where they remained through day 16 of pregnancy. During unilateral pregnancy (Experiment 2), PGF concentration in nongravid and gravid horns was similar (P > 0.8). In contrast, PGE concentrations were greater (P < 0.06) in utero-ovarian venous blood draining the gravid uterine horn. This increase in PGE was associated with enhanced CL function on the ipsilateral ovary as evidenced by an elevated progesterone content and concentration as well as increased CL weights. These data are consistent with a role for conceptus-associated increases in uterine PGE secretion in the local stimulation of luteal function during early pregnancy in the pig.

Estradiol regulation of secretory component: expression by rat uterine epithelial cells

Sex hormones are known to play an important role in the regulation of mucosal immunity in the female reproductive tract. The purpose of this study was to examine the effect of estradiol (E2) on secretory component (SC) expression by epithelial cells in the rat uterus and to determine whether SC mRNA is present in uterine tissues and is under hormonal control. When ovariectomized rats treated with E2 for 3 days and sacrificed 12 h after the last injection, expression of SC on luminal and glandular epithelial cells, as determined by immunohistochemistry, was elevated when compared to control animals. To determine whether E2 regulation of SC involves mRNA synthesis, uterine RNA was extracted and analyzed by Northern blot. These experiments demonstrated that SC RNA is present in uteri from intact rats and markedly increased when ovariectomized animals are treated with E2. In other studies, uterine epithelial cells from adult rats were isolated and grown on permeable membranes for 5 to 10 days. Under these conditions, isolated epithelial cells grow to confluence, form tight junctions, and preferentially secrete SC into the apical medium. These studies identify epithelial cells as a key target cell in the uterus for the regulation of mucosal immunity by E2, which we postulate will play an important role in studies to prevent and/or control the spread of sexually transmitted diseases.

Insulin-like growth factor regulation of human endometrial stromal cell function: coordinate effects on insulin-like growth factor binding protein-1, cell proliferation and prolactin secretion

The insulin-like growth factor (IGF) autocrine/paracrine system is believed to be involved in endometrial differentiation, but there is limited information on the specific cellular functions regulated by IGFs in uterine tissues and their regulation of IGF-binding proteins (IGFBPs). We have investigated the regulation by insulin, IGF-I, and IGF-II, of IGFBP secretion in human endometrial stromal cells decidualized in vitro, and examined the interrelationship between the induced changes in IGFBP levels and the biological responses of stromal cells to IGFs. IGFBPs in conditioned media were analyzed by Western ligand blotting, and IGFBP-1 was quantified by an immunoenzymometric assay (IEMA). In the absence of peptides, decidualized stromal cells secreted 25.5 +/- 3.2 micrograms/day per 10(6) cells of IGFBP-1. Insulin caused a dose-dependent reduction of IGFBP-1 secretion (half-maximal inhibition at < 1 ng/ml) to a maximum of 1% of control values. Northern analysis using a specific cDNA probe showed the expression in decidualized stromal cells of a single 1.5 kb transcript for IGFBP-1, which was absent in insulin-treated cells. The effects of IGF-I and IGF-II on IGFBP-1 secretion were biphasic, with initial stimulation (200-250%) that peaked at 1 and 10 ng/ml, respectively, followed by inhibition at higher concentrations (half maximal inhibition at 3 ng/ml and 30 ng/ml, respectively). The decrease in IGFBP-1 levels in decidualized stromal cultures was associated with the induction of mitogenesis by IGF-I and IGF-II, while IGF effects on prolactin secretion paralleled those of IGFBP-1 secretion, with stimulation (243-324%) in the low concentration range followed by inhibition at higher concentrations. These data indicate that endometrial stromal cell IGFBP-1 is regulated by insulin, at concentrations that are compatible with insulin acting via its own receptor, while the effects of IGF-I and IGF-II on IGFBP-1 secretion, are suggestive of their acting probably through the type I IGF receptor. The present study describes distinct effects of the IGFs on stromal cell IGFBPs, that correlate with changes in the proliferative and secretory responses of decidualized stromal cells to the IGFs. Our findings suggest that complex IGF-IGFBP interactions may participate in the regulation of endometrial cell function, and support a role for IGF-II in stromal cell mitogenesis during decidualization, and as a local regulator of decidual cell function during the late secretory phase and early pregnancy.

Regulation of endometrial cancer cell growth by insulin-like growth factors and the luteinizing hormone-releasing hormone antagonist SB-75

The involvement of IGFs in growth regulation of the Ishikawa endometrial tumor cell line and the possible interference of LH-RH analogues with a potential autocrine or paracrine loop involving IGFs was evaluated. The mitogenic effects of IGF-I, IGF-II, and insulin were compared. IGF-I was found to be 3-fold more potent than IGF-II and 30-fold more potent than insulin, suggesting that the effects of these growth factors are mediated by the IGF-I receptor. Ishikawa endometrial cancer cells secrete IGF-II, but not IGF-I, and insulin (1 microM) stimulates IGF-II release. The LH-RH antagonist [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Cit6, D-Ala10]-GnRH (SB-75, CETRORELIX) inhibited basal and IGF-induced growth. Moreover, this antagonist almost completely inhibited IGF-II release from Ishikawa cells, while having no significant effect on the number or affinity of IGF-I binding sites. Inhibition of IGF-II release occurred at a lower SB-75 concentration than that needed for a reduction in cell number. The ED50 of SB-75 for IGF-II release was 0.3 microM as compared to 1.5 microns concentration which is required for reduction in cell number, suggesting that inhibition of growth factor release precedes cell growth inhibition. We conclude that the LH-RH antagonist SB-75 can inhibit the growth of endometrial cancer cells by interfering with the autocrine action of IGF-II and also by directly inhibiting the growth-stimulatory effects of IGFs, probably through effects on a post-receptor mechanism.

Endometrial expression of mRNA encoding epidermal growth factor receptor in normal and leiomyomatous uteri throughout the menstrual cycle

PROBLEM

To investigate the relationship between the histologic phase and the quantitative expression of epidermal growth factor receptor (EGFR) mRNA in the endometrium of normal and leiomyomatous uteri.

METHODS

To test this relationship, endometrium was collected at hysterectomy from 38 women with a history of regular cycles. Total RNA (20 micrograms) was isolated and analyzed by Northern blot using a human EGFR-specific 32P labeled cDNA probe. The hybridization signals were quantified by densitometry, standardized, and reported in densitometry signal units. Separate portions of the same endometrial specimens were simultaneously prepared for histologic evaluation. The differences between menstrual phases were evaluated by Student's t-test.

RESULTS

EGFR mRNA was expressed in all endometrial tissues tested. Levels were higher in the midproliferative phase than in all other phases for both myomatous and nonmyomatous uteri (P < .05). Myomatous uteri showed lower expression than nonmyomatous uteri in the early and late proliferative phase (P < .05). Age did not appear to alter endometrial EGFR mRNA expression.

CONCLUSION

This data suggest that endometrial EGFR mRNA expression varies in association with the histologic changes of the normal menstrual cycle, and may be associated with the presence of leiomyomata uteri.

Differentiation and uteroglobin gene expression by novel rabbit endometrial cell lines

A clear understanding of the mechanism of differentiation of mammalian endometrial epithelia would significantly improve our knowledge of embryo implantation and placentation. An ideal model for such studies would be immortal endometrial epithelial cell lines which express a well characterized, steroid-responsive, differentiation-specific gene in vitro. We characterized two cell lines which are temperature-sensitive for differentiation. At the non-permissive temperature (39.5 degrees C), in presence of ovarian steroids, these cells express the gene coding for uteroglobin, a steroid-dependent, immunomodulatory/antiinflammatory protein in the rabbit. In addition, when cultured on artificial basement membrane (Matrigel), in presence of ovarian steroids both cell lines developed organized, tubular structures with lumens, reminiscent of an intact endometrium and secreted 33-fold more uteroglobin than the untreated controls. Thus, these immortal cell lines provide a unique model to study endometrial epithelial cell differentiation and steroid hormone action in vitro.

Epidermal growth factor (EGF) replaces estradiol for the initiation of embryo implantation in the hypophysectomized rat

Several studies have provided evidence that epidermal growth factor (EGF) or transforming growth factor alpha (TGF alpha) mediate some of the physiological effects of estrogen. The object of the present study was to determine whether exogenous EGF could initiate embryo implantation in the rat, a response known to depend upon the action of estrogen in a progesterone-primed uterus. Immunocytochemical examination showed the presence of immunoreactive EGF, TGF alpha and the EGF receptor in luminal glandular epithelium of uteri on days 4,5 and 6 of pregnancy. EGF receptor was also present in the implanting embryo and in decidual cells of the uterine stroma. Attempts to initiate implantation by intravenous injection of murine EGF into ovariectomized or hypophysectomized delayed-implanting rats maintained with progesterone were unsuccessful. Implantation sites were found, however, in 24 of 33 (73 per cent) hypophysectomized progesterone-primed rats given 100 micrograms EGF immediately after intrauterine transfer of blastocysts from hypophysectomized delayed implanting animals. Although EGF is capable of initiating implantation in the delayed implanting rat model it remains to be determined whether this growth factor is responsible for the implantation inducing action of estrogen in vivo.

Effects of 9-ene-tetrahydrocannabinol on expression of beta-type transforming growth factors, insulin-like growth factor-I and c-myc genes in the mouse uterus

Effects of cannabinoid on expression of beta-type transforming growth factors (TGF-beta 1, -beta 2 and -beta 3), insulin-like growth factor-I (IGF-I) and c-myc genes in the uteri of adult ovariectomized mice were examined using Northern blot hybridization. Mice were exposed to 9-ene-tetrahydrocannabinol (THC) alone or in combination with an injection of estradiol-17 beta (E2) and/or progesterone (P4), and uteri were analyzed at various times thereafter. TGF-beta isoform messenger RNAs (mRNAs) persisted in ovariectomized uteri and their levels were not altered after THC treatment, whereas an injection of E2 caused a modest increase in TGF-beta 1 and -beta 3 mRNA levels at 24 h. Imposition of THC treatment advanced the stimulatory effects of E2 by changing the timing for the peak of TGF-beta 3 mRNA levels to 12 h. In comparison, E2 treatment substantially elevated the levels of TGF-beta 2 mRNA at 6 h, and THC potentiated this E2 response without affecting the timing for the response. Imposition of P4 treatment did not antagonize any of these responses. P4 treatment alone or with THC had insignificant effects on mRNA levels for these TGF-beta isoforms. Uterine levels of IGF-I and c-myc mRNAs were low in ovariectomized mice and THC did not alter these mRNA levels. In contrast, E2 treatment induced a rapid, but transient, increase in IGF-I and c-myc mRNAs, and THC antagonized the rapid c-myc mRNA response and altered the timing of the IGF-I mRNA response. P4 treatment alone also caused the transient induction of these mRNAs, but THC failed to antagonize these effects. An injection of P4 plus E2 resulted in further modest increases in IGF-I and c-myc mRNA levels as compared to E2 or P4 treatment alone. However, THC did not antagonize these transient stimulatory effects of the combined ovarian steroids. The data suggest that THC should not be classified as estrogenic or antiestrogenic. However, this compound can modulate (potentiate, antagonize and/or alter timing) the effects of ovarian steroids on uterine gene expression.

Modulation of Muc-1 mucin expression in the mouse uterus during the estrus cycle, early pregnancy and placentation

The Muc-1 protein is an integral membrane protein that is expressed apically by simple secretory epithelia in many different organs. We present in this paper a study on Muc-1 protein expression in the mouse uterus during early pregnancy, placentation and the estrus cycle. Muc-1 immunopositive reaction is found in the decidua by day 8 of pregnancy onwards. The observed pattern was unusual, since Muc-1 protein was present in spherical cytoplasmic granules in granular metrial gland cells. Both the intracellular pattern of expression and the lymphoid origin of these cells were striking results. Muc-1 is thought to be an epithelial differentiation marker, and this is the first report of its expression by non-epithelial cells. Our results on Muc-1 expression in the uterus of cycling mice showed that higher levels of Muc-1 mRNA and protein correlate with higher levels of plasma estrogen in the estrus and proestrus phases. However, in ovariectomized mice without hormone replacement, the endometrium expressed high levels of this protein. These levels could not be substantially changed by estrogen, although progesterone reduced the levels of Muc-1 protein associated with the epithelium. These data together with the normal expression in the cycling mice suggest that progesterone might repress Muc-1 expression during the metestrus and diestrus phases. In cycling mice, when plasma progesterone is at its nadir and the estrogen level is elevated in estrus and proestrus phases, Muc-1 concentration would increase to its basal level, not because of estrogen stimulation, but due to lack of progesterone repression.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of messenger ribonucleic acid for epidermal growth factor receptor and its ligands, epidermal growth factor and transforming growth factor-alpha, in human first- and second-trimester fetal ovary and uterus

OBJECTIVES

The epidermal growth factor receptor, a 170 kd polypeptide with tyrosine kinase activity, is used as the common receptor by two homologous polypeptide growth factors, epidermal growth factor and transforming growth factor-alpha. The activation of the epidermal growth factor receptor results in effects including deoxyribonucleic acid synthesis and cellular differentiation. Epidermal growth factor, transforming growth factor-alpha, and the epidermal growth factor receptor are reported to be associated with adult reproduction. However, the pattern of gene expression for the epidermal growth factor receptor and its ligands in human fetal reproductive tissues has not been detailed previously.

STUDY DESIGN

We studied the expression of messenger ribonucleic acid encoding three polypeptides, epidermal growth factor receptor, epidermal growth factor, and transforming growth factor-alpha, in 10-, 15-, 19-, and 22-week human fetal ovaries and uteri. Ribonucleic acid was prepared from the fetal tissues and made into complementary deoxyribonucleic acid by reverse transcription. The complementary deoxyribonucleic acid was amplified by polymerase chain reaction, using primers specific for the human epidermal growth factor receptor, epidermal growth factor, and transforming growth factor-alpha.

RESULTS

We found that epidermal growth factor receptor messenger ribonucleic acid was present in all stages of ovarian and uterine tissues studied. In addition, both epidermal growth factor and transforming growth factor-alpha messenger ribonucleic acid was found in all four stages of ovarian development. Epidermal growth factor messenger ribonucleic acid was detected in all four stages of fetal uterine development.

CONCLUSIONS

This is the first demonstration, to our knowledge, of epidermal growth factor receptor, epidermal growth factor, and transforming growth factor-alpha messenger ribonucleic acid expression in human first- and second-trimester uterus and ovary.

Acute and permanent growth effects in the mouse uterus after neonatal treatment with estrogens

Acute and late effects of neonatal estrogen treatment were studied in NMRI mice treated with diethylstilbestrol (DES) or estradiol-17 beta (E2) on days 1 to 5 after birth (estrogenized females). The uterine wet weight (UWW) response in 6-day-old females, after 5 daily treatments with DES, had a peak at a daily dose of 10(-2) micrograms DES and declined with higher doses. Females (26-day-old) treated with DES or E2 neonatally had a reduced UWW response to a challenge with DES; on a dose basis, DES was more effective neonatally than E2. A single injection with DES or E2 in the neonatal period stimulated mitotic activity in the uterine horn epithelium; the UWW response to a 24-h DES pulse increased from day 2 to 6 after birth, but the uterine epithelial mitotic rate response decreased. Epidermal growth factor (EGF) was a more potent stimulator of mitotic activity than DES or E2. DES inhibited mitotic activity in the uterine cervical epithelium; EGF protected from this DES effect. In adult estrogenized females, EGF-induced uterine stimulation of 3H-thymidine incorporation subsided more rapidly than in control females; uterine epithelium did not respond to EGF in vitro. Uterine stroma of adult estrogenized females is postulated to house a population of cells under nonovarian proliferation control while the uterine epithelium may be under influence of an ovary-dependent proliferation inhibiting factor that is gradually lost under culture conditions.

The trophoblast as an integral component of a macrophage-cytokine network

The trophoblast, an epithelial cell of fetal origin that forms the physical barrier between the mother and developing conceptus, becomes a component of the host immune system during pregnancy. Of the classical immune cells, it most closely resembles the macrophage, also present in high numbers in the pregnant uterus. The macrophage and trophoblast, as cell classes, share characteristics such as phagocytosis, syncytialization, invasiveness, expression of the proteins CD4, CD14, IgG receptor (FcR), non-specific esterase, granulocyte macrophage-CSF (GM-CSF), colony stimulating factor 1 (CSF-1), interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor (TNF-alpha), transforming growth factors (TGF), platelet-alpha derived growth factor (PDGF) and receptors for these cytokines. In the uterus both cell types appear regulated by a common element, the uterine epithelium, that secretes cytokines such as CSF-1, GM-CSF, TNF alpha, TGF beta, IL-6, and leukaemia inhibitory factor (LIF) that target both macrophages and trophoblasts. The common characteristics and regulation that make teleological sense in terms of co-ordinating local uterine immunity during pregnancy may also be important in transmission of congenital diseases such as AIDS. The production by the uterine epithelium of a number of cytokines previously only associated with mononuclear phagocyte production and function predicts the existence of a similar, but broader, shared cytokine network encompassing trophoblast and the principal immune regulatory cell, the T lymphocyte.

Expression of the epidermal growth factor receptor gene is regulated in mouse blastocysts during delayed implantation

The delayed implantation model was used to study epidermal growth factor receptor(s) (EGF-R) in the mouse blastocyst. Delayed implantation and blastocyst dormancy were induced by ovariectomy on day 4 of pregnancy and were maintained by daily (days 5-7) injections of progesterone (P4). Blastocyst activation and implantation were initiated by coinjection of estradiol-17 beta (E2) with P4 on the 3rd day of delay. Immunostaining of EGF-R, autoradiographic detection of 125I-labeled EGF binding, and measurement of EGF-inducible subcellular protein tyrosine phosphorylation demonstrated the loss of EGF-R from blastocysts (dormant) recovered 24 h after ovariectomy or on the 3rd day of P4-maintained delay. However, increased EGF-R levels were detected in blastocysts (activated) recovered 12 or 24 h after E2 injection. Blastocyst EGF-R mRNA levels were quantitated by reverse transcriptase (RT)-PCR and distribution of this mRNA was examined by in situ hybridization. To provide a homologous probe for these studies, a mouse EGF-R partial cDNA was cloned and used as the template for synthesis of antisense- and sense-strand EGF-R RNA. Quantitative RT-PCR demonstrated an 8- to 10-fold reduction in EGF-R mRNA copies per cell in dormant blastocysts. In contrast, an 8-fold increase in EGF-R mRNA copies per cell was detected in activated blastocysts 8 h after injection of E2. In situ hybridization detected EGF-R mRNA in most cells of normal day 4 blastocysts but not in those of dormant blastocysts. These studies establish that expression of the EGF-R gene in mouse blastocysts is tightly regulated by maternal steroid hormonal status.

Contrasting action of antiestrogen (ICI-182780) for preventing initiation of embryo implantation by estradiol or epidermal growth factor (EGF)

The pure estrogen antagonist ICI-182780, at doses above 50 micrograms/kg, effectively inhibited the initiation of embryo implantation in rats when administered on day 4 of pregnancy (day 1 = sperm positive). The same dose inhibited the implantation initiating effect of intravenous 25 ng of estradiol-17 beta in delayed implanting progesterone-primed hypophysectomized rats. In contrast, the anti-estrogen at a dose of 1 mg/kg was ineffective at inhibiting the initiation of implantation induced by intrauterine plus intravenous administration of murine epidermal growth factor to delayed implanting rats. The growth factor also initiated implantation of blastocysts transferred from donor animals injected with the anti-estrogen to progesterone-primed hypophysectomized recipients. The results clearly demonstrate that the implantation initiating effect of the growth factor is not inhibited by a pure estrogen antagonist, and therefore this estrogenic function does not appear to require action initiated by the classical estrogen receptor.

Expression of estrogen receptor gene in mouse oocyte and during embryogenesis

Estrogen is required for oocyte maturation and embryonic development in vivo; however, the mechanism involved is not clear. Since the effect of estrogen is mediated through the estrogen receptor (ER), we examined the ontogeny and expression of the ER gene in mouse oocytes and embryos of various gestational stages using the highly sensitive reverse transcriptase-polymerase chain reaction (RT-PCR) technique. Total RNA, extracted from 40 ovulated oocytes, 2-cell embryos, morulae, and blastocysts, was reverse transcribed into cDNA. A pair of primers flanking the 453-bp region encoding the hormone-binding domain of ER was used for 30 cycles of PCR. The identity of the amplified product was confirmed by sizing and Southern blot hybridization. The results indicated that ER gene is expressed in unfertilized oocytes and cumulus-oocyte complexes. The amount of ER mRNA decreases in 2-cell embryos, coincident with degradation of maternal mRNA. No ER transcript can be detected in the morulae or blastocyst stage when the embryonic genome has been activated. Postimplantation embryos do not contain detectable ER mRNA until gestation day 8. The levels of ER mRNA increase from day 10 to day 18 of gestation. These data suggest that estrogen, secreted by granulosa cells, may directly influence oocyte growth and maturation in vivo. Since estrogen is known to stimulate the production of growth factors in mouse uteri, the absence of ER mRNA in periimplantation embryos suggests that the effects of estrogen on early embryogenesis may be indirect, i.e., through estrogen-regulated growth-promoting factors produced by the reproductive tract. In mid- and late-post-implantation embryos which contain ER mRNA, estrogen may affect embryonic development through the receptor-mediated mechanisms.

The cell biology of blastocyst development

Preimplantation development encompasses the "free"-living period of mammalian embryogenesis, which culminates in the formation of a fluid-filled structure, the blastocyst. Cavitation (blastocyst formation) is accompanied by the expression of a novel set of gene products that contribute directly to the attainment of cell polarity with the trophectoderm, which is both the first epithelium of development and the outer cell layer encircling the inner cell mass of the blastocyst. Several of these gene products have been identified and include the tight junction (ZO-1), Na/K-ATPase (alpha and beta subunits), uvomorulin, gap junction (connexin43), and growth factors such as transforming growth factor-alpha (TGF-alpha) and epidermal growth factor (EGF). This review will examine the role(s) of each of these gene products during the onset and progression of blastocyst formation. The trophectodermal tight junctional permeability seal regulates the leakage of blastocoel fluid and also assists in the maintenance of a polarized Na/K-ATPase distribution to the basolateral plasma membrane domain of the mural trophectoderm. The polarized distribution of the Na/K-ATPase plays an integral role in the establishment of a trans-trophectoderm Na+ gradient, which drives the osmotic accumulation of water across the epithelium into the nascent blastocoelic cavity. The cell adhesion provided by uvomorulin is necessary for the establishment of the tight junctional seal, as well as the maintenance of the polarized Na/K-ATPase distribution. Growth factors such as TGF-alpha and EGF stimulate an increase in the rate of blastocoel expansion, which could, in part, be mediated by secondary messengers that result in an increase in Na/K-ATPase activity. Insight into the mechanism of cavitation has, therefore, directly linked blastocyst formation to trophectoderm cell differentiation, which arises through fundamental cell biological processes that are directly involved in the attainment of epithelial cell polarity.

Gene expression in pre-implantation mammalian embryos

The pre-implantation mammalian embryo is initially under the control of maternal informational macromolecules that are accumulated during oogenesis. Subsequently, the genetic program of development becomes dependent upon new transcription derived from activation of the embryonic genome. Several embryonic transcripts including those that encode growth factors, cell junction components and plasma membrane ion transporters are required for normal progression of the embryo to the blastocyst stage. The pattern of genes expressed and the overall program of development is subject to the influences of genomic imprinting as well as external influences encountered by the embryo within the maternal reproductive tract.

The concentration of estrogen receptors in rabbit uterine myocytes decreases in culture

OBJECTIVE

The purpose of this study was to determine whether the concentration of estrogen receptors in cultured myocytes is preserved after dispersion.

STUDY DESIGN

Primary myocytes were prepared from rabbit myometrium by collagenase dispersion after removing the endometrium and were isolated with Percoll density gradients. The cells were assayed for estrogen receptor concentration at intervals after dispersion by means of a whole-cell binding assay. Unpaired t test was used for comparisons.

RESULTS

The concentration of estrogen receptors on the first day after dispersion was 12,058 +/- 1096 sites per cell (mean +/- SEM) and decreased to 4389 +/- 1223 site per cell within 9 to 14 days after dispersion (63% decline, p < 0.001). A similar decrease was observed when 2 nmol/L estradiol was present in the medium.

CONCLUSION

The concentration of estrogen receptors in isolated rabbit uterine myocytes decreases after dispersion. This may partly explain the difficulty of demonstrating in vitro estrogen effects on myocytes, which are well established in vivo.

Antisense c-myc effects on preimplantation mouse embryo development

Antisense DNA inhibition of gene expression was explored as an approach toward elucidating mechanisms regulating development of preimplantation mammalian embryos. Specifically, a role for the c-myc protooncogene was examined. Detection of c-myc mRNA and immunoreactive nuclear c-myc protein in preimplantation mouse embryos at the eight-cell/morula and blastocyst stages suggested that this DNA-binding protein could be important during early embryo-genesis. The effects of c-myc oligodeoxyribonucleotides (oligos) on the in vitro development of two-cell mouse embryos were examined. Embryos cultured in medium containing an unmodified (phosphodiester) antisense c-myc oligo complementary to the translation initiation codon and spanning the first seven codons exhibited a dose-dependent arrest at the eight-cell/morula stage. At lower concentrations (7.5 microM) this inhibitory effect was specific to the antisense oligo and did not occur with the sense-strand complement or with duplexes of the antisense and sense oligos. However, at 4-fold higher concentrations of DNA (30 microM), all unmodified c-myc oligos were embryotoxic, causing embryos to arrest at the two-cell to four-cell stages. In contrast, almost all (98%) two-cell embryos cultured with a modified (chimeric phosphorothioate/phosphodiester) antisense c-myc oligo (7.5 microM) exhibited developmental arrest at the eight-cell/morula stage, whereas no developmental arrest occurred following incubation with high concentrations of the modified sense complement (30 microM). Culture of freshly recovered eight-cell embryos with antisense c-myc led to the absence of c-myc protein but no change in epidermal growth factor receptor in those embryos that developed a blastocoel. These effects on c-myc were specific for the antisense oligo. These results suggest that c-myc function becomes particularly critical for preimplantation mouse embryos at the eight-cell/morula stage of development and establish that antisense DNA can be successfully applied as an approach toward elucidating the roles of specific genes in preimplantation mammalian embryo development.

Cytokines in rodent reproduction and the cytokine-endocrine interaction

Insights derived from recent studies employing rodent models demonstrate that the synthesis of pluripotent cytokines is an important function of resident cells in the female reproductive tract. Through steroid hormone regulated secretion of these mediators, resident cells appear to coordinate the recruitment and action of leukocytes that are centrally implicated in the dramatic remodelling processes characteristic of reproductive events.

Hydrazine sulfate protection against endotoxin lethality: analysis of effects on expression of hepatic cytokine genes and an acute-phase gene

Hydrazine sulfate (HS) pretreatment protects mice against the lethal effects of bacterial endotoxin lipopolysaccharide (LPS) through mechanisms yet to be established. The liver was examined as a model organ to determine HS effects on (a) LPS activation of leukocyte (Kupffer cell) interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) genes and (b) subsequent cytokine-mediated induction of the acute-phase response as measured by hepatic metallothionein (MT) gene expression. The utility of this model was documented by in situ hybridization which showed that acute induction by LPS of the IL-1 beta gene occurred in cells found in liver sinusoids, consistent with Kupffer cells, whereas induction of the MT gene occurred in hepatocytes. The cell specific expression of these genes was further verified by Northern blot hybridization to LPS-treated liver RNA which showed that the LPS-mediated increase in hepatic cytokine mRNA levels, unlike that of MT, was not prevented by D-galactosamine (D-GalN) treatment. Northern blot hybridization established that HS pretreatment did not block the acute induction of hepatic cytokine mRNAs (IL-1 beta and TNF-alpha) by LPS nor did it induce these cytokine mRNAs in the absence of LPS. Northern blot hybridization further established that HS did not prevent LPS-mediated activation of hepatocyte MT gene expression. Thus, HS does not prevent LPS from activating liver leukocytes. These results also suggest that HS pretreatment neither prevents the general release of cytokines from LPS activated leukocytes nor the general induction of acute-phase protein gene expression in hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)