Biomedical subjects

A Makrigiannakis

Publications and source records attributed to A Makrigiannakis.

At least 19 recordsLinked to original sources

PubMed2001

Endometrial and myometrial corticotropin-releasing hormone (CRH): its regulation and possible roles.

In human endometrium, both epithelial and stroma cells produce corticotropin-releasing hormone (CRH). Both types of cells also possess specific CRH-binding sites indicating a local effect of endometrial CRH. The transcription of the CRH gene in human endometrium is under the control of steroid hormones and locally produced prostanoids and interleukins. Endometrial CRH interacts with locally produced prostaglandins and interleukins. Based on these observations it can be hypothesized that CRH, prostaglandins and interleukins form a network responsible for the communication between epithelial and stromal cells, at the level of the endometrium, and between endometrial and myometrial cells at the level of uterus. The net product of these interaction is the micro-regulation of the decidualizing process and the preparation of endometrium for the implantation/nidation of the conceptus. Indeed, this network may represent the core of the intrauterine neuroendocrine-immune interactions involved in the decidualization of stroma and implantation of blastocyst. In addition, this network appears to be essential for the fine-tuning of myometrial tone.

Animals↗

PubMed2001

Corticotropin-releasing hormone promotes blastocyst implantation and early maternal tolerance.

The semi-allograft embryo in the blastocyst stage implants itself in the endometrium, yet no immune rejection processes are activated. Embryonic trophoblast and maternal decidua produce corticotropin-releasing hormone (CRH) and express Fas ligand (FasL), a proapoptotic cytokine. We found that antalarmin, a CRH receptor type 1 antagonist, decreased FasL expression and promoted apoptosis of activated T lymphocytes, an effect which was potentiated by CRH and inhibited by antalarmin. Female rats treated with antalarmin showed a marked decrease in implantation sites and live embryos and diminished endometrial FasL expression. Embryos from mothers that lacked T cells or from syngeneic matings were not rejected when the mothers were given antalarmin. These findings suggested that locally produced CRH promotes implantation and maintenance of early pregnancy primarily by killing activated T cells.

Animals↗

PubMed2001

The Fas/FasL apoptotic pathway is involved in kappa-opioid-induced apoptosis of human endometrial stromal cells.

Human endometrium expresses specific kappa-opioid binding sites and their endogenous ligands, the dynorphins. In neural crest-derived tissues, kappa-opioids affect apoptosis, a phenomenon of major significance in endometrial stroma physiology. Our hypothesis was that endometrial kappa-opioids may play a role in endometrial stromal cell apoptosis. Thus, we examined the effect of the synthetic kappa-opioid agonist, U69593, on the apoptotic rate of human endometrial stromal cells in primary culture. Apoptosis of endometrial stromal cells was elevated after 3 h exposure to 100 nmol/l U69593, and remained elevated for up to 3 days. This effect was dose-dependent and was reversed by the general opioid antagonist, naloxone, suggesting that it is mediated via opioid receptors. In parallel, semi-quantitative Western blot and flow cytometry analysis showed that U69593 caused a rapid but transient up-regulation of Fas protein, suggesting that its effect on apoptosis is mediated by activation of the Fas/FasL apoptotic pathway. Additionally, U69593 increased the content of the anti-apoptotic members of the Bcl-2 family of proteins, the Bcl-2 and Bcl-x(L), whereas it had no significant effect on the apoptosis-promoting homologues Bax, Bcl-x(S) and Bak. This implies that a transient survival mechanism is activated in stromal cells as a parallel rescue response to the apoptosis-inducing factor. In conclusion, our data suggest that endometrial opioid dynorphins may participate in the apoptotic processes related to endometrial tissue remodelling during early pregnancy or menstruation.

Apoptosis↗

PubMed2001

Differential expression of the coxsackievirus and adenovirus receptor regulates adenovirus infection of the placenta.

The molecular mechanisms and pathologic significance of placental viral infections are poorly understood. We investigated factors that regulate placental infection by adenovirus, which is the most common viral pathogen identified in fetal samples from abnormal pregnancies (i.e., fetal growth restriction, oligohydramnios, and nonimmune fetal hydrops). We also determined the pathologic significance of placental adenovirus infection. Northern hybridization, flow cytometry, and immunostaining revealed that placental expression of the coxsackievirus and adenovirus receptor (CAR) varied with gestational age and trophoblast phenotype. The CAR was continuously expressed in invasive or extravillous trophoblast cells but not in villous trophoblast cells. We postulate that the villous syncytiotrophoblast, which does not express CAR and is resistant to adenovirus infection, limits the transplacental transmission of viral pathogens, including adenovirus. Conversely, extravillous trophoblast cells underwent apoptosis when infected by adenovirus in the presence of decidual lymphocytes (which simulated the maternal immune response to viral infection). Thus, adenovirus infection and/or the maternal immune response to adenovirus infection induced the death of placental cell types that expressed CAR. Consequently, we speculate that adenovirus infection of extra-villous trophoblast cells may negatively impact the process of placental invasion and predispose the mother and fetus to adverse reproductive outcomes that result from placental dysfunction.

Adenoviridae Infections↗

PubMed2001

Expression of Wilms' tumor suppressor gene (WT1) in human endometrium: regulation through decidual differentiation.

The Wilms' tumor suppressor gene (WT1) encodes a zinc-finger containing transcription factor that is selectively expressed in the developing urogenital tract and functions as a tissue-specific developmental regulator. In addition to its gene-regulatory function through DNA binding properties, WT-1 also regulates transcription by formation of protein-protein complexes. These properties place WT-1 as a major regulator of cell growth and differentiation. In view of these observations, we studied WT1 mRNA and protein in human endometrial extracts and in endometrial stromal cells (ESCs) differentiating into decidual cells in vitro, by RT-PCR and Western blotting, respectively. WT1 protein expression was also studied in situ in the proliferative and the secretory phase of the menstrual cycle in the early pregnant state. Analysis by PCR of total RNA prepared from human ESCs demonstrated the presence of WT1 mRNA and four WT1 mRNA splice variants. Western blot analysis of nuclear protein extracts from ESCs yielded one immunoreactive protein of the expected size (approximately 52-54 kDa) recognized by the WT1 antibody. Immunohistochemical staining showed that WT1 protein is localized only to nuclei of human endometrial stromal cells. It remains constant in the proliferative and the secretory phase of the menstrual cycle and is increased remarkably during decidualization in early pregnancy. ESCs decidualized in vitro were investigated for WT-1 expression, which confirmed that decidualizing stimuli (E2, medroxy-progesterone-acetate, and relaxin for 12 d or cAMP and progesterone for 1-4 d) induced WT-1 mRNA (P < 0.05) and increased protein levels (P < 0.05). These data indicate that in humans the WT1 gene is expressed in ESCs and its mRNA and protein levels remain constant in the proliferative and the secretory phase of the menstrual cycle and that WT1 mRNA and protein expression increases significantly in ESCs when these cells differentiate into decidual cells.

Cells, Cultured↗

PubMed2000

The adhesion molecule CEACAM1 (CD66a, C-CAM, BGP) is specifically expressed by the extravillous intermediate trophoblast.

CEACAM1 (CD66a, C-CAM, BGP) is an adhesion molecule of the carcinoembryonic antigen family which has been shown to be normally expressed at the apical pole of epithelial cells, including the apical pole of endometrial surface and glandular epithelia. The purpose of the present study was to investigate its expression pattern at the maternal-fetal interface, and thus to determine whether CEACAM1 could be implicated in the human implantation process. For this purpose, we performed immunohistochemistry using the 4D1/C2 monoclonal antibody (mAb) as well as flow cytometry and Western blot on isolated trophoblast populations. On the maternal side of the maternal-fetal interface, CEACAM1 was present in epithelial cells of pregnancy endometrium as well as in small endometrial vessels, whereas it was absent from decidual cells. On the fetal side, CEACAM1 was strongly expressed by the extravillous (intermediate) trophoblast at the implantation site, as well as by extravillous trophoblast cells with invasive phenotype in primary culture, as shown by flow cytometry and Western blot. Expression was also observed in placental villous core vessels but was absent from both villous cyto- and syncytiotrophoblasts throughout the pregnancy. We conclude that, given its specific expression pattern, CEACAM1 can be a useful marker for extravillous intermediate trophoblast and might be functionally implicated in mediating trophoblast/endometrial and/or trophoblast/endothelial interactions during the trophoblastic invasion of the endometrium.

Antigens, CD↗

PubMed2000

Inhibitory G protein alpha subunit (Gi alpha) expression and localization during human trophoblast differentiation.

OBJECTIVE: Cyclic adenosine monophosphate (cAMP) participates in the regulation of processes associated with trophoblast syncytialization. As guanosine triphosphate (GTP)-binding regulatory proteins (G-proteins) modulate adenylate cyclase activity, the present study investigated the expression and regulation of the alpha subunit of inhibitory G protein (Gi alpha) during human trophoblast differentiation in vitro. STUDY DESIGN: Protein levels and the immunolocalization of the protein at a subcellular-level were assessed. RESULTS: Expression of Gi alpha protein decreased during syncytialization. Moreover, Gi alpha transmigrated from a predominantly cell membrane-associated to a predominantly perinuclear location during the process. CONCLUSION: These results suggest that Gi alpha is regulated and may be implicated in cAMP-dependent events during the terminal differentiation of human trophoblasts.

Adenosine Diphosphate Ribose↗

PubMed2000

Multi-attenuated herpes simplex virus-1 mutant G207 exerts cytotoxicity against epithelial ovarian cancer but not normal mesothelium and is suitable for intraperitoneal oncolytic therapy.

Recombinant strains of herpes simplex virus-1 (HSV-1) harboring mutations in the infected cell product (ICP)34.5 region lose their neurovirulence and replicate more efficiently in dividing tumor cells than stationary cells, becoming replication-selective oncolytic agents. Additional mutation of the ICP6 gene, which encodes ribonucleotide reductase, further impairs the ability of HSV-1 mutants to replicate in normal cells, enhancing tumor selectivity. The present study investigated the effect of HSV-G207, a recombinant HSV-1 lacking ICP34.5 and ICP6, against epithelial ovarian cancer (EOC) in vitro and in vivo in a mouse xenograft model. To assess the selectivity of multimutated HSV-G207 against malignant cells, HSV-G207 and wild-type HSV-F were comparatively tested against normal human peritoneal mesothelial cells and EOC cells in vitro. HSV-G207 infected both EOC cells and mesothelial cells; however, unlike EOC cells, mesothelial cells provided a poor substrate for replication of HSV-G207. In contrast to wild-type HSV-F, HSV-G207 exerted a potent oncolytic effect on EOC cells but spared normal mesothelial cells in vitro. Primary EOC cells were more sensitive to the virus than established EOC cell lines. A single intraperitoneal injection of HSV-G207 resulted in a significant reduction in tumor volume and tumor spread in vivo. HSV-G207 was shown to penetrate deeply within tumor nodules and caused no apparent intraperitoneal toxicity. Oncolytic therapy with multimutated replication-restricted HSV may offer a novel approach in the treatment of EOC.

Animals↗

PubMed2000

Corticotrophin-releasing hormone (CRH) interacts with inflammatory prostaglandins and interleukins and affects the decidualization of human endometrial stroma.

The hypothalamic neuropeptide, corticotrophin-releasing hormone (CRH), which is also produced by human endometrium, has been shown to induce its decidualization in vitro. This process, induced mainly by progesterone, has characteristics of an aseptic inflammatory reaction, and is modulated by locally produced pro-inflammatory factors. In humans, prostaglandin E(2) (PGE(2)) enhances while interleukin (IL)-1 inhibits the decidualizing effect of progesterone. The aim of the present work was to test the hypothesis that CRH might affect the decidualization of human endometrium interacting with these factors. Therefore, we studied its effects on the production of pro-inflammatory interleukins IL-1, IL-6 and of PGE(2) from human endometrial stromal cells in primary culture. The results strongly suggest that CRH decidualizes stromal cells, as judged by the appearance of cytokeratins and the production of prolactin, two established markers of decidualization. In parallel to its effect on decidualization, CRH also decreased the production of PGE(2), while it increased the production of IL-1 and IL-6. Exposure of endometrial stromal cells to IL-6 also caused decidualization. The data presented here suggest that endometrial CRH regulates the production of local modulators of decidualization, i.e. PGE(2), IL-1 and IL-6. We postulate that, through the regulation of these factors, CRH acts as a local fine-tuner of decidualization initiated by progesterone.

Cell Differentiation↗

PubMed2000

Kappa opioids and TGFbeta1 interact in human endometrial cells.

The transforming growth factor beta1 (TGFbeta1) is a major regulator of human endometrial function. Human endometrium possesses specific opioid binding sites, the majority of which belong to the kappa type, for which the prodynorphin-derived opioids are the endogenous ligands. Since these two systems interact in several other tissues we postulated that opioids may affect the production of TGFbeta1 in human endometrium. We have found that kappa opioids exerted a time- and dose-dependent inhibitory effect on TGFbeta1 production from endometrial stromal and epithelial cells and from the Ishikawa human endometrial adenocarcinoma cell line. This effect was reversible by the specific opioid antagonist diprenorphine. To examine if this effect represents a paracrine endometrial response to locally produced kappa opioids we searched for the presence of the endogenous kappa opioid receptor ligands. Indeed, the prodynorphin transcript was detectable on Northern blots from normal and tumoral human endometrial cells; its size was that of the pituitary transcript, i.e. approximately 2.4 kb long. Most immunoreactive dynorphin from human endometrium had a molecular weight of 8 kDa. Finally, immunofluorescence staining of normal and tumoral human endometrial cells revealed the presence of dynorphin-positive cytoplasmic secretory granules. Taken together, our data suggest that in human endometrium, kappa opioids and the TGFbeta1 form a paracrine network which appears to be retained by the Ishikawa human endometrial adenocarcinoma cell line.

Cells, Cultured↗

PubMed2000

Progesterone is an autocrine/paracrine regulator of human granulosa cell survival in vitro.

Ovarian follicles are composed of granulosa cells (GC), which undergo apoptosis within 24 hours of culture in serum-free medium. The present study was designed to assess the role of progesterone in regulating human GC survival. Human GC were isolated from follicular aspirates of women undergoing in vitro fertilization. GC were then cultured for 24 hours in serum-free media supplemented with progesterone and/or the progesterone antagonist RU486 and dexamethasone. Cells were then fixed and assessed for apoptosis by in situ end labeling of DNA fragments, cell cycle analysis of DNA content, and electron microscopy. When compared with controls, progesterone reduced and RU486 increased the percentage of apoptotic GC (p < 0.05), whereas dexamethasone had no effect. In addition, RU486 inhibited the protective effect of progesterone on GC survival (p < 0.05). Taken together, these data indicate that progesterone inhibits human GC apoptosis, and this effect is mediated through the progesterone receptor.

Adult↗

PubMed2000

Follicular atresia and luteolysis. Evidence of a role for N-cadherin.

Studies suggest that cell-cell interactions may regulate apoptosis; and, in particular, the calcium-dependent cell adhesion molecule N-cadherin has been shown to be capable of modulating this process. Here, we review the evidence that N-cadherin is expressed by human granulosa cells (GCs) and mediates cell-cell adhesion between GCs. There is strong correlation between N-cadherin expression by granulosa or luteal cells and follicular survival in isolated follicles and archival tissue sections. There exists a strong expression of the molecule by GCs in follicles of the resting pool, of growing antral follicles, and of healthy corpora lutea. In contrast, the molecule is lost in degenerating GCs of atretic follicles and in luteal cells of the late luteal phase. Further, the experimental evidence demonstrates that cell-cell adhesion is critical to the survival of GCs and that N-cadherin-mediated cell-cell adhesion is a critical mediator of survival signals and inhibits apoptosis in these cells. Possible mechanisms by which apoptosis may be triggerred in GCs include the downregulation of N-cadherin, which is mediated, at least in part, through the enzymatic cleavage of the extracellular domain of the molecule. Collectively, these observations suggest that downregulation of N-cadherin or the absence of a functional extracellular domain of the molecule prevent GC aggregation and is associated with GC apoptosis. We propose that N-cadherin-mediated GC signaling plays a central role in follicular and luteal cell survival.

Apoptosis↗

PubMed2000

Surface morphology of the human endometrium. Basic and clinical aspects.

The human endometrium is an extremely sensitive target for steroid hormones. During the menstrual cycle, this tissue undergoes dynamic changes that are reflected on the surface morphology of the epithelium and that can be followed by scanning electron microscopy. The morphologic changes peak at the midsecretory phase, with the formation of the so-called pinopodes. Increasing evidence suggests that these pinopodes are accurate markers for endometrial receptivity, and their detection may be of high clinical utility in the preparation of endometrium before embryo transfer. This article recapitulates published figures of endometrial ultrastructure and presents some unpublished data from ongoing studies.

Endometrium↗

PubMed2000

Regulated expression and potential roles of p53 and Wilms' tumor suppressor gene (WT1) during follicular development in the human ovary.

It has been previously demonstrated that the gonadotropin-mediated inhibition ofapoptosis in rat ovarian granulosa cells is associated with changes in the expression of several cell death-regulatory genes, including p53. In addition, it has been shown that the actions of p53 may be amplified through a cooperative interaction with the Wilms' tumor suppressor gene product (WT1). Based on these findings, the present studies were conducted to determine whether p53 and WT1 are expressed and gonadotropin regulated in the human ovary and to study the relationship between tumor suppressor gene expression and apoptosis in human granulosa/lutein cells (GCs). Analysis of total RNA prepared from human GCs using the RT-PCR demonstrated the presence of p53 messenger RNA (mRNA) and four WT1 mRNA splice variants. These observations were supported by Northern blot analysis of total RNA prepared from human GCs, which revealed the presence of a single (approximately 2.8 kb) p53 mRNA transcript and two primary (approximately 1.8 and approximately 3.5 kb) WT1 mRNA transcripts. Western blot analysis of nuclear protein extracts from human GCs yielded one immunoreactive protein of the expected size (approximately 53 kDa) recognized by a p53 antibody and one immunoreactive protein of the expected size (approximately 52-54 kDa) recognized by the WT1 antibody. Immunohistochemical staining showed that both molecules were localized to nuclei of human GCs and were coordinately regulated during follicular development. Immunofluorescence analysis showed that p53 protein was localized exclusively to nuclei of GCs undergoing apoptosis during in vitro culture and was similarly localized to nuclei and cytoplasm of apoptotic granulosa cells in atretic follicles in vivo. To further evaluate whether human GC apoptosis is linked to increased expression of tumor suppressor genes, we analyzed levels of p53 and WT1 mRNA and protein in GCs induced to undergo apoptosis in vitro. Healthy (nonapoptotic) GCs snap-frozen immediately after isolation from patients undergoing in vitro fertilization-embryo transfer possessed relatively low, but detectable, levels of p53 and WT1 mRNA and protein. However, following serum-free culture to induce apoptosis, p53 mRNA and protein levels increased significantly after 24 h, paralleling the increase in the number of apoptotic GCs. The induction of both p53 mRNA and protein in GCs was inhibited by the addition of human CG to the culture medium. In contrast, WT1 mRNA and protein levels remained constitutive in GCs incubated for 24 h compared with GCs snap-frozen immediately after isolation. We conclude that the p53 and WT1 genes are expressed at the mRNA and protein levels in human GCs and that expression of p53 is regulated during follicular maturation. Nuclear accumulation of p53 protein occurs in human GCs during apoptosis in vitro and in vivo, and p53 mRNA and protein are up-regulated in GCs starved of hormonal support but down-regulated by the presence of human CG. We propose that the products of these two principal tumor suppressor genes serve as important regulators of human follicular development and corpus luteum function.

Adult↗

PubMed2000

Oncolytic herpes simplex virus-1 lacking ICP34.5 induces p53-independent death and is efficacious against chemotherapy-resistant ovarian cancer.

Replication-restricted herpes simplex virus-1 (HSV-1) strains lacking ICP34.5 are emerging as powerful anticancer agents against several solid tumors including epithelial ovarian cancer (EOC). Although chemotherapy-resistant tumors would be likely candidates for treatment with HSV-1 mutants lacking ICP34.5, the efficacy of these mutants on such tumors is unknown. In the present study, we investigated whether chemotherapy resistance affects the response of ovarian cancer cells to HSV-R3616, an ICP34.5-deficient, replication-restricted HSV-1. Primary EOC cultures obtained from patients who varied in their responses to platinum/paclitaxel induction chemotherapy displayed similar sensitivity to HSV-R3616. Similarly, chemotherapy-sensitive ovarian cancer cells A2780 and PA-1, possessing wild-type p53, and their respective chemotherapy-resistant clones A2780/200CP, lacking p53 function, and PA-1/E6, permanently expressing the HPV E6 gene, were equally sensitive to HSV oncolysis. Because wild-type HSV can kill cells by apoptosis and nonapoptotic mechanisms, we investigated the involvement of apoptosis and the role of the p53 tumor suppressor gene in oncolysis induced by HSV-R3616. Infection of ovarian cancer cell lines by HSV-R3616 was followed by cell death via apoptosis or nonapoptotic mechanisms as noted by morphology, cell cycle analysis, and in situ TUNEL assay. p53 protein levels remained unchanged, and Bax protein levels decreased in cells possessing intact p53 and that mainly underwent HSV-induced apoptosis. Loss of p53 function did not affect the frequency or rate of apoptosis or the sensitivity of EOC cells to the oncolytic effect of HSV-R3616. These results suggest that recombinant HSV-1 lacking ICP34.5 is capable of killing ovarian cancer cells that lack p53 function, resist apoptosis, and/or are chemotherapy resistant. These data support the hypothesis that HSV-based oncolytic therapy may be efficacious in chemotherapy-resistant tumors, including tumors that are deficient in p53.

Antineoplastic Agents↗

PubMed1999

N-cadherin-mediated human granulosa cell adhesion prevents apoptosis: a role in follicular atresia and luteolysis?

Studies suggest that cell-cell interactions may regulate apoptosis, and in particular, the calcium-dependent cell adhesion molecule N-cadherin has been shown to be capable of modulating this process. Rat granulosa cells (GCs) are known to express N-cadherin whereas cAMP is known to induce apoptosis in human and rat GCs. Based on these observations, we hypothesized that N-cadherin regulates human GC apoptosis via a cAMP-dependent mechanism. N-cadherin expression was evaluated in ovarian follicles and corpora lutea utilizing immunohistochemical techniques and in luteinized GCs in culture using immunoblotting, flow cytometric analysis, immunohistochemistry, and indirect immunofluorescence techniques utilizing anti-N-cadherin antibodies directed against both the extracellular and cytoplasmic domains of the molecule. Apoptosis was assessed by TUNEL and DNA fragmentation analysis and confirmed by flow cytometric cell cycle analysis and electron microscopy. The rate of GC apoptosis was found to be two- to three-fold lower among aggregated cells, as compared with single cells. N-cadherin was found to be expressed by aggregating GCs in vitro and GCs cultured in the presence of either N-cadherin function disrupting antibodies or peptides exhibiting enhanced rates of apoptosis. GCs in situ stained intensely for N-cadherin in preantral and normal growing preovulatory follicles as well as early corpora lutea. N-cadherin was weak in atretic follicles and regressing corpora lutea. Exposure of GCs to cAMP increased apoptosis while decreasing N-cadherin protein expression in a dose-dependent manner. Cell culture under serum-free conditions increased apoptosis and decreased N-cadherin expression, in part through cleavage of the extracellular domain of the molecule. The metalloproteinase inhibitor 1-10-phenanthroline inhibited the cleavage of the extracellular domain of N-cadherin and concomitantly inhibited the serum-deprivation-induced apoptosis of aggregated GCs. Collectively, these observations suggest that down-regulation of N-cadherin or the absence of a functional extracellular domain of the molecule prevents cell aggregation and is associated with GC apoptosis. In addition, cAMP induces apoptosis in a dose-dependent manner, and this process is dependent, at least in part, on regulation of the N-cadherin molecule at the surface of the cells. We conclude that N-cadherin-mediated GC signaling plays a central role in follicular and luteal cell survival.

Adult↗

PubMed1999

Insulin and insulin-like growth factor-I and -II modulate human granulosa-lutein cell steroidogenesis: enhancement of steroidogenic acute regulatory protein (StAR) expression.

Insulin and insulin-like growth factors (IGF)-I and -II stimulate granulosa cell steroidogenesis. Since steroidogenic acute regulatory protein (StAR) regulates the rate-limiting step in steroid hormone biosynthesis, the ability of insulin and IGF to modulate StAR protein and mRNA expression was examined in two human granulosa cell culture systems: (i) proliferating granulosa-lutein cells and (ii) luteinized-granulosa cells derived during in-vitro fertilization (IVF). In proliferating granulosa-lutein cells, IGF-I and IGF-II increased StAR protein approximately 4-5-fold, while insulin and 8-bromoadenosine 3',5'-cAMP (8-Br-cAMP) increased amounts of StAR protein 2.5- and 6-fold respectively. A combination of IGFs/insulin and 8-Br-cAMP increased StAR 7-9-fold. Luteinized granulosa cells also had increased StAR expression after treatment with IGF-I (2. 8-fold), IGF-II (3-fold), insulin (2.5-fold) and 8-Br-cAMP (4. 5-fold). Progesterone production generally followed a pattern similar to StAR protein in both cell systems. In proliferating granulosa-lutein cells, both IGF-I and insulin increased StAR mRNA (3-fold) and 8-Br-cAMP increased StAR mRNA 4-fold, whereas a combination of IGF-I and 8-Br-cAMP had an additive effect on StAR mRNA expression (7-fold). Transient transfection of proliferating granulosa-lutein cells with StAR promoter-luciferase reporter constructs demonstrated that IGF-I, IGF-II, and insulin had no effect on the StAR promoter activity, while 8-Br-cAMP stimulated StAR promoter function. The results indicate that: (i) IGFs and insulin stimulate StAR mRNA and protein expression in human granulosa-lutein cells; (ii) IGF-I and 8-Br-cAMP have an additive effect on StAR gene expression; and (iii) IGF-I increases StAR mRNA and protein by a mechanism that does not involve activation of the proximal StAR gene promoter.

Blotting, Northern↗

PubMed1999

The decidualizing effect of progesterone may involve direct transcriptional activation of corticotrophin-releasing hormone from human endometrial stromal cells.

The hypothalamic neuropeptide corticotrophin-releasing hormone (CRH) is also produced by human endometrial cells and is directly involved in the decidualization process as a paracrine inducer. The aim of the present work was to examine the effect of progesterone, the main decidualizing factor, on endometrial CRH, in primary cultures of human endometrial stromal cells. The effect of progesterone was examined by measuring the effects of medroxyprogesterone acetate (MPA) on (i) the concentration of immunoreactive CRH in isolated human endometrial stromal cells and (ii) the activity of the CRH promoter in human endometrial stromal cells transfected with a 0.9 kb fragment of the 5'-flanking region of the human CRH gene coupled to luciferase reporter. The data show that MPA increased the production and secretion of immunoreactive CRH from stromal cells and induced the activity of the CRH promoter, both in a dose-dependent manner. These effects were partially reversed by a molar excess of the antiprogestin RU 486 and were completely abolished in the presence of 100 nmol/l of the cAMP inhibitor, Rp-cAMP. The effect of progesterone on the CRH promoter requires the existence of an intact CRH sequence since experiments carried out with a deleted palindromic cAMP response element (CRE: 5'-TGACGTCA) at -224 bp of the CRH promoter resulted in a complete loss of MPA effect. In conclusion, these data provide evidence that progesterone induces the transcription of CRH gene in human endometrial stroma. This effect coupled with the decidualizing properties of progesterone and CRH may indicate that progesterone and CRH form a decidualizing local pathway within the human endometrium.

8-Bromo Cyclic Adenosine Monophosphate↗