Erkut Attar

Aromatase excess in cancers of breast, endometrium and ovary

Pathogenesis and growth of three common womens cancers (breast, endometrium and ovary) are linked to estrogen. A single gene encodes the key enzyme for estrogen biosynthesis named aromatase, inhibition of which effectively eliminates estrogen production in the entire body. Aromatase inhibitors successfully treat breast cancer, whereas their roles in endometrial and ovarian cancers are less clear. Ovary, testis, adipose tissue, skin, hypothalamus and placenta express aromatase normally, whereas breast, endometrial and ovarian cancers overexpress aromatase and produce local estrogen exerting paracrine and intracrine effects. Tissue-specific promoters distributed over a 93-kb regulatory region upstream of a common coding region alternatively control aromatase expression. A distinct set of transcription factors regulates each promoter in a signaling pathway- and tissue-specific manner. In cancers of breast, endometrium and ovary, aromatase expression is primarly regulated by increased activity of the proximally located promoter I.3/II region. Promoters I.3 and II lie 215 bp from each other and are coordinately stimulated by PGE(2) via a cAMP-PKA-dependent pathway. In breast adipose fibroblasts exposed to PGE(2) secreted by malignant epithelial cells, PKC is also activated, and this potentiates cAMP-PKA-dependent induction of aromatase. Thus, inflammatory substances such as PGE(2) may play important roles in inducing local production of estrogen that promotes tumor growth.

Progesterone resistance in endometriosis: Link to failure to metabolize estradiol

Endometriosis is the most common cause of pelvic pain and affects an estimated 5 million women in the US. The biologically active estrogen estradiol (E2) is the best-defined mitogen for the growth and inflammation processes in the ectopic endometriotic tissue that commonly resides on the pelvic organs. Progesterone and progestins may relieve pain by limiting growth and inflammation in endometriosis but a portion of patients with endometriosis and pelvic pain do not respond to treatment with progestins. Moreover, progesterone-induced molecular changes in the eutopic (intrauterine) endometrial tissue of women with endometriosis are either blunted or undetectable. These in vivo observations are indicative of resistance to progesterone action in endometriosis. The molecular basis of progesterone resistance in endometriosis may be related to an overall reduction in the levels of progesterone receptors (PRs) and the lack of the PR isoform named progesterone receptor B (PR-B). In normal endometrium, progesterone acts on stromal cells to induce secretion of paracrine factor(s). These unknown factor(s) act on neighboring epithelial cells to induce the expression of the enzyme 17beta-hydroxysteroid dehydrogenase type 2 (17beta-HSD-2), which metabolizes the biologically active estrogen E2 to estrone (E1). In endometriotic tissue, progesterone does not induce epithelial 17beta-HSD-2 expression due to a defect in stromal cells. The inability of endometriotic stromal cells to produce progesterone-induced paracrine factors that stimulate 17beta-HSD-2 may be due to the lack of PR-B and very low levels of progesterone receptor A (PR-A) observed in vivo in endometriotic tissue. The end result is deficient metabolism of E2 in endometriosis giving rise to high local concentrations of this local mitogen. The cellular and molecular mechanisms underlying progesterone resistance and failure to metabolize E2 in endometriosis are reviewed.

Estrogen Receptor-β, Estrogen Receptor-α, and Progesterone Resistance in Endometriosis

Loss of progesterone signaling in the endometrium may be a causal factor in the development of endometriosis, and progesterone resistance is commonly observed in women with this disease. In endometriotic stromal cells, the levels of progesterone receptor (PR), particularly the PR-B isoform, are significantly decreased, leading to a loss of paracrine signaling. PR deficiency likely underlies the development of progesterone resistance in women with endometriosis who no longer respond to progestin therapy. Here we review the complex epigenetic and transcriptional mechanisms leading to PR deficiency. The initial event may involve deficient methylation of the estrogen receptor (ER)beta promoter resulting in pathologic overexpression of ERbeta in endometriotic stromal cells. We speculate that alterations in the relative levels of ERbeta and ERalpha in endometrial tissue dictate E2-regulated PR expression, such that a decreased ERalpha-tauomicron-ERbeta ratio may result in suppression of PR. In this review, we propose a molecular model that may be responsible for changes in ERbeta and ERalpha leading to PR loss and progesterone resistance in endometriosis.

Role of Estrogen Receptor-β in Endometriosis

Endometriosis is an estrogen-dependent disease. The biologically active estrogen, estradiol, aggravates the pathological processes (e.g., inflammation and growth) and the symptoms (e.g., pain) associated with endometriosis. Abundant quantities of estradiol are available for endometriotic tissue via several mechanisms including local aromatase expression. The question remains, then, what mediates estradiol action. Because estrogen receptor (ER)β levels in endometriosis are >100 times higher than those in endometrial tissue, this review focuses on this nuclear receptor. Deficient methylation of the ERβ promoter results in pathological overexpression of ERβ in endometriotic stromal cells. High levels of ERβ suppress ERα expression. A severely high ERβ-to-ERα ratio in endometriotic stromal cells is associated with suppressed progesterone receptor and increased cyclo-oxygenase-2 levels contributing to progesterone resistance and inflammation. ERβ-selective estradiol antagonists may serve as novel therapeutics of endometriosis in the future.

Modulation of leukemia inhibitory factor gene expression and protein biosynthesis in the human fallopian tube

OBJECTIVE The fallopian tube is the site of fertilization and early embryonic growth and a common site of ectopic implantation. Although the factors responsible for early embryogenesis and implantation are incompletely understood, leukemia inhibitory factor may have an important role in early embryonic development and implantation. We set out to evaluate the production and modulation of leukemia inhibitory factor in the fallopian tube. STUDY DESIGN We first investigated leukemia inhibitory factor messenger ribonucleic acid levels in fallopian tubes. We then investigated leukemia inhibitory factor messenger ribonucleic acid and protein production in tubal epithelial and stromal cell cultures. RESULTS Leukemia inhibitory factor messenger ribonucleic acid is expressed in the fallopian tube with only slight variation during the menstrual cycle; however, it is markedly elevated in association with ectopic pregnancy. The level is higher in the tubal mucosa than in the remaining layers and is higher in the more distal segments of the fallopian tube. Estradiol and progesterone did not modulate leukemia inhibitory factor expression in epithelial or stromal cell cultures. Interleukin-1 alpha, tumor necrosis factor-alpha, and transforming growth factor-beta enhanced leukemia inhibitory factor expression in epithelial and stromal cells, with transforming growth factor-beta 1 enhancing expression by fourfold in stromal cells. Epithelial cells secreted high levels of leukemia inhibitory factor compared with stromal cells (332 +/- 89 vs 25 +/- 42 pg/mg total protein). Yet stromal cells treated with transforming growth factor-beta alone or in combination with epidermal growth factor and platelet-derived growth factor, as well as TNF-alpha alone or in combination with interleukin-1 alpha enhanced secretion of leukemia inhibitory factor at or above the levels found with epithelial cells. CONCLUSIONS We speculate that the high constitutive levels of leukemia inhibitory factor expressed in the ampullary portion of the fallopian tube may play a role in early embryonic development. Additionally, elevated expression with ectopic implantation and the marked induction of secretion in the tubal stroma by growth factors and cytokines suggest a link between inflammation, leukemia inhibitory factor, and tubal ectopic pregnancies.

Upstream Stimulatory Factor-2 Regulates Steroidogenic Factor-1 Expression in Endometriosis

Local estrogen biosynthesis is a major factor in the pathogenesis of endometriosis. Aberrant expression of steroidogenic acute regulatory protein (StAR) and aromatase in endometriotic tissue leads to an up-regulation of estrogen production. The transcription factor steroidogenic factor-1 (SF-1) activates the promoters of both StAR and aromatase in endometriotic tissue. We investigated differences in SF-1 expression in endometriotic tissue and normally located endometrium to elucidate the mechanism underlying increased StAR and aromatase activities in endometriosis. Serial deletion and site-directed mutants of the SF-1 promoter showed that an E-box sequence was critical for its activity in endometriotic stromal cells. EMSAs showed that the upstream stimulatory factor (USF) 1 and 2 in nuclear extracts from endometrial and endometriotic stromal cells bound to the E-box. Chromatin-immunoprecipitation-PCR assay, however, demonstrated in intact cells that binding activity of USF2 to the SF-1 promoter was strikingly higher than that of USF1 in endometriotic stromal cells and that USF1 or USF2 binding activity was hardly detectable in endometrial stromal cells. Moreover, knockdown of USF2 but not USF1 resulted in robust and consistent down-regulation of SF-1 and its target genes StAR and aromatase in endometriotic stromal cells. USF2 but not USF1 mRNA and protein levels were significantly higher in endometriotic vs. endometrial stromal cells. In vivo, USF2 mRNA and immunoreactive USF2 levels in endometriotic tissues were strikingly higher than those in endometrium. Taken together, the elevated levels of USF2 in endometriosis account for, in part, the aberrant expression of SF-1 and its target gene StAR and aromatase.

Steroidogenic factor-1 and endometriosis

Endometriosis is a common and chronic disease characterized by persistent pelvic pain and infertility. Estradiol is essential for growth and inflammation in endometriotic tissue. The complete cascade of steroidogenic proteins/enzymes including aromatase is present in endometriosis leading to de novo estradiol synthesis. PGE(2) induces the expression of the genes that encode these enzymes. Upon PGE(2) treatment, coordinate recruitment of the nuclear receptor SF-1 to the promoters of these steroidogenic genes is the key event for estradiol synthesis. SF-1 is the key factor determining that an endometriotic cell will respond to PGE(2) by increased estradiol formation. The presence of SF-1 in endometriosis and its absence in endometrium is determined primarily by the methylation of its promoter. The key steroidogenic enzyme in endometriosis is aromatase encoded by a single gene because its inhibition blocks all estradiol biosynthesis. Aromatase inhibitors diminish endometriotic implants and associated pain refractory to existing treatments in affected women.

Effect of leukaemia inhibitory factor on long-term sperm motility and survival

Leukaemia inhibitory factor (LIF) is expressed at high constitutive levels in the human Fallopian tubal epithelium. In this study, the effect of human recombinant LIF on sperm motility and survival in vitro was investigated. Human spermatozoa were incubated in sperm washing medium that contained various concentrations of LIF at 37 degrees C and under 5% of CO(2) in air for up to 48 h. Sperm motion characteristics were measured using a sperm motility analyser. Sperm survival was determined by the hypo-osmotic swelling test. The effect of LIF on sperm motility was concentration-dependent and maximal effect was observed at a concentration of 5 ng/ml. Sperm motility was significantly higher after 24 h exposure to LIF compared with control (P < 0.001). Sperm survival was also prolonged in a concentration-dependent manner. LIF significantly enhanced sperm survival at higher concentrations (10 ng/ml) and the result was significant after 48 h exposure (P < 0.05). LIF increased long-term sperm motility and survival in vitro.

Hypermobility syndrome in 105 women with pure urinary stress incontinence and in 105 controls

Abstract. We compared the frequency of Hypermobility Syndrome (HS) in 105 patients with urinary stress incontinence (USI) with the frequency of HS in 105 healthy controls that matched for age and parity. A Beighton score (BS) of more than 3 was used to make the clinical diagnosis of HS. Thirty-six patients (34.28%) from the USI group and 28 patients (26.66%) from the control group were diagnosed as HS. The mean BS values were 6.44±0.35 and 5.21±0.29 respectively. The difference between the two groups was statistically significant (P<0.05).

Use of hematopoietic stem cells in obstetrics and gynecology.

Stem cells can be used in different areas of obstetrics and gynecology. Adult stem cells are specialized cells found within many tissues of the body where they function in tissue homeostasis and repair. In vitro they have been shown to differentiate into a wide variety of cell types. Hematopoietic stem cells (HSC) have been used to set up therapeutic strategies for the treatment of gynecological solid tumors such as ovarian cancer. Stem cells can be used for prenatal transplantation and in utero gene therapy. Also stem cells can be used in infertility and IVF for research and treatment.