Sex disparity in colonic adenomagenesis involves promotion by male hormones, not protection by female hormones.

It recently has been recognized that men develop colonic adenomas and carcinomas at an earlier age and at a higher rate than women. In the Apc(Pirc/+) (Pirc) rat model of early colonic cancer, this sex susceptibility was recapitulated, with male Pirc rats developing twice as many adenomas as females. Analysis of large datasets revealed that the Apc(Min/+) mouse also shows enhanced male susceptibility to adenomagenesis, but only in the colon. In addition, WT mice treated with injections of the carcinogen azoxymethane (AOM) showed increased numbers of colonic adenomas in males. The mechanism underlying these observations was investigated by manipulation of hormonal status. The preponderance of colonic adenomas in the Pirc rat model allowed a statistically significant investigation in vivo of the mechanism of sex hormone action on the development of colonic adenomas. Females depleted of endogenous hormones by ovariectomy did not exhibit a change in prevalence of adenomas, nor was any effect observed with replacement of one or a combination of female hormones. In contrast, depletion of male hormones by orchidectomy (castration) markedly protected the Pirc rat from adenoma development, whereas supplementation with testosterone reversed that effect. These observations were recapitulated in the AOM mouse model. Androgen receptor was undetectable in the colon or adenomas, making it likely that testosterone acts indirectly on the tumor lineage. Our findings suggest that indirect tumor-promoting effects of testosterone likely explain the disparity between the sexes in the development of colonic adenomas.

Correction: Intestinal Tumorigenesis Is Not Affected by Progesterone Signaling in Rodent Models.

[This corrects the article DOI: 10.1371/journal.pone.0022620.].

Intestinal tumorigenesis is not affected by progesterone signaling in rodent models.

Clinical data suggest that progestins have chemopreventive properties in the development of colorectal cancer. We set out to examine a potential protective effect of progestins and progesterone signaling on colon cancer development. In normal and neoplastic intestinal tissue, we found that the progesterone receptor (PR) is not expressed. Expression was confined to sporadic mesenchymal cells. To analyze the influence of systemic progesterone receptor signaling, we crossed mice that lacked the progesterone receptor (PRKO) to the Apc(Min/+) mouse, a model for spontaneous intestinal polyposis. PRKO-Apc(Min/+) mice exhibited no change in polyp number, size or localization compared to Apc(Min/+). To examine effects of progestins on the intestinal epithelium that are independent of the PR, we treated mice with MPA. We found no effects of either progesterone or MPA on gross intestinal morphology or epithelial proliferation. Also, in rats treated with MPA, injection with the carcinogen azoxymethane did not result in a difference in the number or size of aberrant crypt foci, a surrogate end-point for adenoma development. We conclude that expression of the progesterone receptor is limited to cells in the intestinal mesenchyme. We did not observe any effect of progesterone receptor signaling or of progestin treatment in rodent models of intestinal tumorigenesis.

A signaling-selective, nanomolar potent allosteric low molecular weight agonist for the human luteinizing hormone receptor.

Luteinizing hormone (LH) and human chorionic gonadotropin (hCG) activate the LH receptor/cyclic AMP (cAMP) signaling pathway to induce ovulation. As an alternative to parenterally administered hCG to treat anovulatory infertility, orally active low molecular weight (LMW) LHR agonists have been developed at Organon. In this paper, we present the mechanism of action of a prototypic, nanomolar potent and almost full LHR agonist, Org 43553. Org 43553 interacts with the endodomain of the LHR, whereas LH acts via the N-terminal exodomain. LH stimulates the cAMP pathway with an EC50 of 35 pM, but this stimulation is not antagonized by simultaneous incubation with Org 43553. At nanomolar concentrations, LH also stimulates phospholipase C (PLC), but Org 43553 is hardly able to do so. In contrast, Org 43553 inhibits LH-induced PLC (IC50 approximately 10 nM). While Org 43553 stimulates dissociation of [125I]hCG from the LHR and reduces [125I]hCG binding, LH reduces specific [3H]Org 43553 binding. We conclude that Org 43553 is a signaling-selective, allosteric LHR agonist. We hypothesize that Org 43553 and LH induce a similar LHR conformation necessary for activating adenylyl cyclase, which initiates most, if not all, physiological responses of LH.

Localization of LGR7 gene expression in adult mouse brain using LGR7 knock-out/LacZ knock-in mice: correlation with LGR7 mRNA distribution.

Knowledge of the distribution of the relaxin receptor, LGR7, in the brain provides a basis for studies of the physiologic actions of relaxin. LGR7 knock-out (KO) mice were produced by the in-frame replacement of LGR7 exon 10 and 11 with a LacZ-reporter cassette (knock-in [KI]), and in this study we used LGR7-KO/LacZ-KI mice to determine the regional/cellular distribution of LGR7 gene expression in adult mouse brain by assessing beta-galactosidase activity in perfusion-fixed sections. High densities of beta-galactosidase-positive neurons were detected in anterior olfactory and claustrum/endopiriform nuclei, deep layers of cortex (particularly somatosensory), and the subiculum. Low to moderate densities were detected in olfactory bulb (periglomerular layer), cingulate cortex, subfornical organ, hippocampal CA2/dentate hilus, amygdala, hypothalamus, and thalamus. This LGR7/LacZ expression appears to recapitulate that of native LGR7 in wild-type mice and provides a model to further investigate the phenotype of LGR7-responsive neurons in the brain and to help reveal functions associated with central relaxin signaling.

Effect of controlled ovarian hyperstimulation in IVF on endometrial gene expression profiles.

Controlled ovarian hyperstimulation (COH) used in IVF produces lower implantation rates per embryo transferred compared to natural cycles utilized in ovum donation, suggesting a suboptimal endometrial development. Endometrial receptivity has recently been investigated in natural menstrual cycles with the aid of microarray technology. The aim of this study is to investigate the impact of COH using urinary gonadotrophins with a long protocol with GnRH agonists without progesterone supplementation (similar to the natural cycle) on endometrial gene expression profiles during the window of implantation by comparing the profiles at day hCG + 7 of COH versus LH + 7 of a previous natural cycle in the same women. For this purpose we have used microarray technology by Affymetrix (GeneChip HG_U133A), which allows more than 22,000 genes to be tested simultaneously. Results were validated by semi-quantitative PCR and quantitative PCR experiments. We found that more than 200 genes showed a differential expression of more than 3-fold when COH and normal cycles were compared at hCG + 7 versus LH + 7. We simultaneously re-analysed the LH + 2 versus LH + 7 endometrial gene expression profiles in previous natural cycles in the same subject using this specific GeneChip, the results obtained were consistent with our own published results. This is the first time that gene expression profiles of the endometrium during COH are reported. The large degree of gene expression disturbance is surprising and highlights the need for further efforts to optimize COH protocols.

Valproate-induced alterations in human theca cell gene expression: clues to the association between valproate use and metabolic side effects.

Valproic acid (VPA) is an anti-epileptic drug that has been associated with polycystic ovary syndrome (PCOS)-like symptoms, including increased ovarian androgen production. The hyperandrogenemia likely reflects the stimulatory action of VPA on theca cell androgen synthesis and has been correlated to its activity as a histone deacteylase inhibitor in these cells. To determine whether VPA induces a PCOS-like genomic phenotype, we compared the gene expression profiles of untreated (UNT) normal, VPA-treated normal, and UNT PCOS theca cells. Hierarchal cluster analysis demonstrated similarities in the gene expression profiles of VPA-treated normal and PCOS theca cells. Statistical analysis identified 1,050 transcripts that have significantly altered mRNA abundance in both VPA-treated normal and UNT PCOS theca cells compared with normal UNT theca cells. Among these 1,050 transcripts were cAMP-GEFII and TRB3, which have increased and decreased mRNA abundance, respectively. The altered abundance of these two mRNAs was correlated to increased basal and insulin-induced phosphorylation of protein kinase B (Akt/PKB). Thus these studies indicate that VPA- and PCOS-induced changes in gene expression enhance Akt/PKB signal transduction in human theca cells. Furthermore, common changes in gene expression in PCOS and VPA-treated normal theca cells suggest a possible mechanism for the development of PCOS-like symptoms, including increased steroid synthesis and arrested follicle development in women receiving chronic VPA therapy.

Abnormal gene expression profiles in human ovaries from polycystic ovary syndrome patients.

Polycystic ovary syndrome (PCOS) represents the most common cause of anovulatory infertility and affects 5-10% of women of reproductive age. The etiology of PCOS is still unknown. The current study is the first to describe consistent differences in gene expression profiles in human ovaries comparing PCOS patients vs. healthy normoovulatory individuals. The microarray analysis of PCOS vs. normal ovaries identifies dysregulated expression of genes encoding components of several biological pathways or systems such as Wnt signaling, extracellular matrix components, and immunological factors. Resulting data may provide novel clues for ovarian dysfunction in PCOS. Intriguingly, the gene expression profiles of ovaries from (long-term) androgen-treated female-to-male transsexuals (TSX) show considerable overlap with PCOS. This observation provides supportive evidence that androgens play a key role in the pathogenesis of PCOS. Presented data may contribute to a better understanding of dysregulated pathways in PCOS, which might ultimately reveal novel leads for therapeutic intervention.

Global gene expression profiling of human endometrial receptivity.

Scientific knowledge on the molecular changes that occur during the window of implantation is fundamental for the understanding of human reproduction. To gain a global molecular understanding of human endometrial receptivity, we have compared gene expression profiles of pre-receptive (day LH + 2) versus receptive (LH + 7) in well characterized human endometrial biopsies. The samples were analyzed using the Affymetrix HG-95A array, a high density oligonucleotide microarray comprising more than 12,000 genes. In this work, we present part of our results and a comparison with similar works published in the literature. Identified genes include not only genes previously documented to be involved in implantation but also genes for which a role in endometrial receptivity, or even endometrial expression, has not been previously described. Collectively, these studies identify new candidate markers that may be used to diagnose unequivocally the receptive endometrium.

Uterine Msx-1 and Wnt4 signaling becomes aberrant in mice with the loss of leukemia inhibitory factor or Hoxa-10: evidence for a novel cytokine-homeobox-Wnt signaling in implantation.

Successful implantation absolutely depends on the reciprocal interaction between the implantation-competent blastocyst and the receptive uterus. Expression and gene targeting studies have shown that leukemia inhibitory factor (LIF), a cytokine of the IL-6 family, and Hoxa-10, an abdominalB-like homeobox gene, are crucial to implantation and decidualization in mice. Using these mutant mice, we sought to determine the importance of Msx-1 (another homeobox gene formerly known as Hox-7.1) and of Wnt4 (a ligand of the Wnt family) signaling in implantation because of their reported functions during development. We observed that Msx-1, Wnt4, and a Wnt antagonist sFRP4 are differentially expressed in the mouse uterus during the periimplantation period, suggesting their role in implantation. In addition, we observed an aberrant uterine expression of Msx-1 and sFRP4 in Lif mutant mice, and of Wnt4 and sFRP4 in Hoxa-10 mutant mice, further reinforcing the importance of these signaling pathways in implantation. Collectively, the present results provide evidence for a novel cytokine-homeotic-Wnt signaling network in implantation.

Linkage analysis of extremely discordant and concordant sibling pairs identifies quantitative trait loci influencing variation in human menopausal age.

Age at natural menopause may be used as parameter for evaluating the rate of ovarian aging. Environmental factors determine only a small part of the large variation in menopausal age. Studies have shown that genetic factors are likely to be involved in variation in menopausal age. To identify quantitative-trait loci for this trait, we performed a genomewide linkage study with age at natural menopause as a continuous quantitative phenotype in Dutch sister pairs, through use of a selective sampling scheme. A total of 165 families were ascertained using extreme selected sampling and were genotyped for 417 markers. Data were analyzed by Haseman-Elston regression and by an adjusted variance-components analysis. Subgroup analyses for early and late menopausal age were conducted by Haseman-Elston regression. In the adjusted variance-components analysis, 12 chromosomes had a LOD score of > or =1.0. Two chromosomal regions showed suggestive linkage: 9q21.3 (LOD score 2.6) and Xp21.3 (LOD score 3.1). Haseman-Elston regression showed rather similar locations of the peaks but yielded lower LOD scores. A permutation test to obtain empirical P values resulted in a significant peak on the X chromosome. To our knowledge, this is the first study to attempt to identify loci responsible for variability in menopausal age and in which several chromosomal regions were identified with suggestive and significant linkage. Although the finding of the region on the X chromosome comes as no surprise, because of its widespread involvement in premature ovarian failure, the definition of which particular gene is involved is of great interest. The region on chromosome 9 deserves further consideration. Both findings require independent confirmation.

Impaired nipple development and parturition in LGR7 knockout mice.

LGR7 is a G-protein coupled receptor with structural homology to the gonadotrophin and thyrotrophin receptors. Recently, LGR7 was deorphanized, and it was shown that relaxin is the ligand for LGR7. To further study the function of this receptor, mice deficient for LGR7 were generated by replacing part of the transmembrane-encoding region with a LacZ reporter cassette. Here we show that LGR7 is expressed in various tissues, including the uterus, heart, brain, and testis. Fertility studies using female LGR7-/- mice showed normal fertility and litter size. However, some females were incapable of delivering their pups, and several pups were found dead. Moreover, all offspring died within 24 to 48 h after delivery because female LGR7-/- mice were unable to feed their offspring due to impaired nipple development. In some male LGR7-/- mice, spermatogenesis was impaired, leading to azoospermia and a reduction in fertility. Interestingly, these phenomena were absent in mutant mice at older ages or in later generations. Taken together, results from LGR7 knockout mice indicate an essential role for the LGR7 receptor in nipple development during pregnancy. Moreover, a defect in parturition was observed, suggesting a role for LGR7 in the process of cervical ripening.

Gene expression pattern and immunoreactive protein localization of LGR7 receptor in human endometrium throughout the menstrual cycle.

Relaxin (RLX) is a pregnancy-associated polypeptide hormone. In non-pregnant women, the peak of circulating relaxin coincides with the window of endometrial receptivity and both in vivo and in vitro experiments showed that it plays a role in the decidualization process. Recently, two receptors, LGR7 and LGR8, have been identified as high affinity receptors for relaxin. Here we describe LGR7 mRNA and protein expression in human endometrium using semi-quantitative and quantitative fluorescent PCR (Q-PCR) and immunohistochemical analyses. Three different experimental designs were used. First, endometrial biopsies from five different phases of the menstrual cycle were analysed. Secondly, we assessed the early luteal phase in more detail. Finally we analysed the expression at LH+2 (2 days after the natural LH surge, pre-receptive endometrium) versus LH+7 (receptive endometrium) within the same menstrual cycle from the same patient to avoid inter-cycle or inter-person variations in gene expression. Our results indicate that there is no consistent regulation of LGR7 mRNA expression, neither during the menstrual cycle nor during the early-mid-luteal phase. In general, we observed a large degree of variation in LGR7 mRNA expression levels between patients. LGR7 immunoreactive protein was identified in all stages of the menstrual cycle. LGR7 protein was localized in both the epithelial and the stromal compartments, except for the mid-luteal phase when the expression was restricted to the endometrial epithelium. We conclude that no consistent regulation of LGR7 mRNA expression can be detected in human endometrium during the menstrual cycle.

The molecular phenotype of polycystic ovary syndrome (PCOS) theca cells and new candidate PCOS genes defined by microarray analysis.

Polycystic ovary syndrome (PCOS) affects 5% of reproductive aged women and is the leading cause of anovulatory infertility. A hallmark of PCOS is excessive theca cell androgen secretion, which is directly linked to the symptoms of PCOS. Our previous studies demonstrated that theca cells from PCOS ovaries maintained in long term culture persistently secrete significantly greater amounts of androgens than normal theca cells, suggesting an intrinsic abnormality. Furthermore, previous studies suggested that ovarian hyperandrogenemia is inherited as an autosomal dominant trait. However, the genes responsible for ovarian hyperandrogenemia of PCOS have not been identified. In this present study, we carried out microarray analysis to define the gene networks involved in excess androgen synthesis by the PCOS theca cells in order to identify candidate PCOS genes. Our analysis revealed that PCOS theca cells have a gene expression profile that is distinct from normal theca cells. Included in the cohort of genes with increased mRNA abundance in PCOS theca cells were aldehyde dehydrogenase 6 and retinol dehydrogenase 2, which play a role in all-trans-retinoic acid biosynthesis and the transcription factor GATA6. We demonstrated that retinoic acid and GATA6 increased the expression of 17alpha-hydroxylase, providing a functional link between altered gene expression and intrinsic abnormalities in PCOS theca cells. Thus, our analyses have 1) defined a stable molecular phenotype of PCOS theca cells, 2) suggested new mechanisms for excess androgen synthesis by PCOS theca cells, and 3) identified new candidate genes that may be involved in the genetic etiology of PCOS.

Gene expression profiling of human endometrial receptivity on days LH+2 versus LH+7 by microarray technology.

In humans, embryonic implantation and reproduction depends on the interaction of the embryo with the receptive endometrium. To gain a global molecular understanding of human endometrial receptivity, we compared gene expression profiles of pre-receptive (day LH+2) versus receptive (LH+7) endometria obtained from the same fertile woman (n = 5) in the same menstrual cycle in five independent experiments. Biopsies were analysed using the Affymetrix HG-U95A array, a DNA chip containing approximately 12,000 genes. Using the pre-defined criteria of a fold change >/=3 in at least four out of five women, we identified 211 regulated genes. Of these, 153 were up-regulated at LH+7 versus LH+2, whereas 58 were down-regulated. Amongst these 211 regulated genes, we identified genes that were known to play a role in the development of a receptive endometrium, and genes for which a role in endometrial receptivity, or even endometrial expression, has not been previously described. Validation of array data was accomplished by mRNA quantification by real time quantitative fluorescent PCR (Q-PCR) of three up-regulated [glutathione peroxidase 3 (GPx-3), claudin 4 (claudin-4) and solute carrier family 1 member 1 (SLC1A1)] genes in independent LH+2 versus LH+7 endometrial samples from fertile women (n = 3) and the three up-regulated genes throughout the menstrual cycle (n = 15). Human claudin-4 peaks specifically during the implantation window, whereas GPx-3 and SLC1A1 showed highest expression in the late secretory phase. In-situ hybridization (ISH) experiments showed that GPx-3 and SLC1A1 expression was restricted to glandular and luminal epithelial cells during the mid- and late luteal phase. The present work adds new and important data in this field, and highlights the complexity of studying endometrial receptivity even using global gene-expression analysis.

Ligand selectivity of gonadotropin receptors. Role of the beta-strands of extracellular leucine-rich repeats 3 and 6 of the human luteinizing hormone receptor.

The difference in hormone selectivity between the human follicle-stimulating hormone receptor (hFSH-R) and human luteinizing hormone/chorionic gonadotropin receptor (hLH-R) is determined by their approximately 350 amino acid-long N-terminal receptor exodomains that allow the mutually exclusive binding of human follicle-stimulating hormone (hFSH) and human luteinizing hormone (hLH) when these hormones are present in physiological concentrations. The exodomains of each of these receptors consist of a nine-leucine-rich repeat-containing subdomain (LRR subdomain) flanked by N- and C-terminal cysteine-rich subdomains. Chimeric receptors, in which the structural subdomains of the hFSH-R exodomain were substituted with those of the hLH-R, showed a similar high responsiveness to human chorionic gonadotropin (hCG) and hLH as long as they harbored the LRR subdomain of the hLH-R. In addition, these chimeric receptors showed no responsiveness to hFSH. The LRR subdomains of the gonadotropin receptor exodomains are predicted to adopt a horseshoe-like conformation, of which the hormone-binding concave surface is composed of nine parallel beta-strands. Receptors in which individual beta-strands of the hFSH-R were replaced with the corresponding hLH-R sequences revealed that hCG and hLH selectivity is predominantly determined by hLH-R beta-strands 3 and 6. A mutant receptor in which the hFSH-R beta-strands 3 and 6 were substituted simultaneously with their hLH-R counterparts displayed a responsiveness to hCG and hLH similar to that of the wild type hLH-R. Responsiveness to hFSH was not affected by most beta-strand substitutions, suggesting the involvement of multiple low-impact determinants for this hormone.

Thyrostimulin, a heterodimer of two new human glycoprotein hormone subunits, activates the thyroid-stimulating hormone receptor.

Human thyrotropin (TSH), luteotropin (LH), follitropin (FSH), and chorionic gonadotropin are members of the heterodimeric glycoprotein hormone family. The common alpha subunit forms noncovalent heterodimers with different beta subunits. Two novel human glycoprotein hormonelike genes, alpha2 (A2) and beta5 (B5), recently have been identified. Using a yeast two-hybrid assay, the two subunits were found as potential heterodimerization partners. Immunological analyses confirmed the heterodimerization of A2 and B5 in transfected cells and their colocalization in the anterior pituitary. Recombinant A2/B5 heterodimeric glycoproteins, purified using cation exchange and size fractionation chromatography, activated human TSH receptors, but not LH and FSH receptors, and showed high affinity to TSH receptors in a radioligand receptor assay. The heterodimer also stimulated cAMP production and thymidine incorporation by cultured thyroid cells and increased serum thyroxine levels in TSH-suppressed rats in vivo. This new heterodimeric glycoprotein hormone was named as thyrostimulin based on its thyroid-stimulating activity. The expression of thyrostimulin in the anterior pituitary known to express TSH receptors suggested a paracrine mechanism. The present discovery of a new ligand based on genomic approaches could facilitate the understanding of the physiological roles of extra-thyroid TSH receptor systems and the structural-functional basis of receptor signaling by related glycoprotein hormones.