Yuval Yung

Exposure of fallopian tube epithelium to follicular fluid mimics carcinogenic changes in precursor lesions of serous papillary carcinoma

OBJECTIVES Ovulation-related inflammation is suspected to have a causal role in ovarian carcinogenesis, but there are no human models to study the molecular pathways. Our aim is to develop such an ex-vivo model based on human fallopian tube (FT) epithelium exposed to human follicular fluid (FF). METHODS FT epithelium was dissociated from normal surgical specimens. FF was obtained from donors undergoing in-vitro fertilization. The cells were cultured on collagen-coated Transwells and incubated with FF for various periods of time. The transcriptomic changes resulting from FF treatment were profiled using Affymetrix expression arrays. Specific characteristics of the FT pre-cancerous lesions were studied using immunohistochemistry, immunofluorescence, RT-PCR and XTT assay. RESULTS We show that FF exposure causes up-regulation of inflammatory and DNA repair pathways. Double stranded DNA breaks are induced. There is a minor increase in cell proliferation. TP53, which is the hallmark of the precursor lesion in-vivo, is accumulated. Levels of expression and secretion of Interleukin-8 are significantly increased. CONCLUSIONS Our model addresses the main non-genetic risk factor for ovarian cancer, namely the impact of ovulation. This study demonstrates the biological implications of in-vitro exposure of human FT epithelial cells to FF. The model replicates elements characterizing the precursor lesions of ovarian cancer, and warrants further investigation of the linkage between repeated exposure to ovulation-related damage and accumulation of neoplastic changes.

High expression of luteinizing hormone receptors messenger RNA by human cumulus granulosa cells is in correlation with decreased fertilization.

OBJECTIVE To elucidate the LH receptor (LHR) expression patterns in human granulosa cells (GCs) from antral to preovulatory stages, and to investigate a correlation to oocyte function. DESIGN Luteinized preovulatory GCs were obtained from preovulatory follicles aspirated during IVF (≥ 17 mm). The GCs from small- (<10 mm) and medium-sized (10-15 mm) follicles were obtained during in vitro maturation (IVM) procedures. Cumulus GCs were obtained during oocyte denudation for intracytoplasmatic sperm injection (ICSI) procedures (IVF). SETTING Referral center. PATIENT(S) Seventy IVF patients and 20 IVM patients. INTERVENTION(S) GC collection. MAIN OUTCOME MEASURE(S) The LHR expression levels in mural and cumulus GCs of different follicular sizes and their correlation to oocyte outcome. RESULT(S) The LHR expression increased with follicle size and was higher in mural GCs compared with cumulus cells. The LHR expression in cumulus GCs from preovulatory follicles was higher in metaphase II (MII) oocytes than in metaphase I or germinal vesicle oocytes (IVF). Unexpectedly, higher expression of LHR in cumulus GCs of MII oocytes correlated with decreased fertilization rates. CONCLUSION(S) The LHR expression in small follicles obtained in IVM suggests a role for hCG administration during IVM procedures. Overexpression of LHR in cumulus GCs of MII oocytes may signal malfunction of oocytes and low fertilization capacity.

Characterization of the human cumulus cell transcriptome during final follicular maturation and ovulation

Cumulus expansion and oocyte maturation are central processes in ovulation. Knowledge gained from rodent and other mammalian models has revealed some of the molecular pathways associated with these processes. However, the equivalent pathways in humans have not been thoroughly studied and remain unidentified. Compact cumulus cells (CCs) from germinal vesicle cumulus oocyte complexes (COCs) were obtained from patients undergoing in vitro maturation (IVM) procedures. Expanded CCs from metaphase 2 COC were obtained from patients undergoing IVF/ICSI. Global transcriptome profiles of the samples were obtained using state-of-the-art RNA sequencing techniques. We identified 1746 differentially expressed (DE) genes between compact and expanded CCs. Most of these genes were involved in cellular growth and proliferation, cellular movement, cell cycle, cell-to-cell signaling and interaction, extracellular matrix and steroidogenesis. Out of the DE genes, we found 89 long noncoding RNAs, of which 12 are encoded within introns of genes known to be involved in granulosa cell processes. This suggests that unique noncoding RNA transcripts may contribute to the regulation of cumulus expansion and oocyte maturation. Using global transcriptome sequencing, we were able to generate a library of genes regulated during cumulus expansion and oocyte maturation processes. Analysis of these genes allowed us to identify important new genes and noncoding RNAs potentially involved in COC maturation and cumulus expansion. These results may increase our understanding of the process of oocyte maturation and could ultimately improve the efficacy of IVM treatment.

Screening of human pluripotent stem cells using CGH and FISH reveals low-grade mosaic aneuploidy and a recurrent amplification of chromosome 1q.

Pluripotency and proliferative capacity of human embryonic stem cells (hESCs) make them a promising source for basic and applied research as well as in therapeutic medicine. The introduction of human induced pluripotent cells (hiPSCs) holds great promise for patient-tailored regenerative medicine therapies. However, for hESCs and hiPSCs to be applied for therapeutic purposes, long-term genomic stability in culture must be maintained. Until recently, G-banding analysis was considered as the default approach for detecting chromosomal abnormalities in stem cells. Our goal in this study was to apply fluorescence in-situ hybridization (FISH) and comparative genomic hybridization (CGH) for the screening of pluripotent stem cells, which will enable us identifying chromosomal abnormalities in stem cells genome with a better resolution. We studied three hESC lines and two hiPSC lines over long-term culture. Aneuploidy rates were evaluated at different passages, using FISH probes (12,13,16,17,18,21,X,Y). Genomic integrity was shown to be maintained at early passages of hESCs and hiPSCs but, at late passages, we observed low rates mosaiciam in hESCs, which implies a direct correlation between number of passages and increased aneuploidy rate. In addition, CGH analysis revealed a recurrent genomic instability, involving the gain of chromosome 1q. This finding was detected in two unrelated cell lines of different origin and implies that gains of chromosome 1q may endow a clonal advantage in culture. These findings, which could only partially be detected by conventional cytogenetic methods, emphasize the importance of using molecular cytogenetic methods for tracking genomic instability in stem cells.

Localization of luteinizing hormone receptor protein in the human ovary

The luteinizing hormone receptor (LHR) plays a pivotal role during follicular development. Consequently, its expression pattern is of major importance for research and has clinical implications. Despite the accumulated information regarding LHR expression patterns, our understanding of its expression in the human ovary, specifically at the protein level, is incomplete. Therefore, our aim was to determine the LHR protein localization and expression pattern in the human ovary. We examined the presence of LHR by immunohistochemical staining of human ovaries and western blots of mural granulosa and cumulus cells aspirated during IVF treatments. We were not able to detect LHR protein staining in primordial or primary follicles. We observed equivocal positive staining in granulosa cells and theca cells of secondary follicles. The first appearance of a clear signal of LHR protein was observed in granulosa cells and theca cells of small antral follicles, and there was evidence of increasing LHR production as the follicles mature to the pre-ovulatory stage. After ovulation, LHR protein was ubiquitously produced in the corpus luteum. To confirm the expression pattern in granulosa cells and cumulus cells, we performed western blots and found that LHR expression was stronger in granulosa cells than in cumulus cells, with the later demonstrating low, but still significant, amounts of LHR protein. In summary, we conclude that LHR protein starts to appear on granulosa cells and theca cells of early antral follicles, and low but significant expression of LHR exists also in the cumulus cells. These results may have implications for the future design of clinical protocols and culture mediums for in vitro fertilization and especially in vitro maturation of oocytes.

Anti-Müllerian hormone is highly expressed and secreted from cumulus granulosa cells of stimulated preovulatory immature and atretic oocytes

This study investigated anti-Müllerian hormone (AMH) expression and secretion from cumulus granulosa cells (GC) and steroidogenesis in follicular fluids (FF) with relation to oocyte maturational stages and fertilization capacity in large preovulatory follicles. This prospective study included 53 ovulatory women undergoing intracytoplasmic sperm injection. FF and cumulus GC from 140 large preovulatory follicles were individually obtained during oocyte retrieval. Main outcome measures were oocyte maturation, fertilization and embryo quality. FF were assayed for AMH, progesterone, 17β-oestradiol and testosterone. Cumulus GC were assayed for AMH mRNA expression. AMH mRNA expression and secretion in cumulus GC in preovulatory follicles containing germinal-vesicle (GV) and metaphase-I (MI) oocytes were significantly higher than follicles containing MII oocytes (P<0.01 and P<0.0001, respectively). In addition, FF AMH concentrations from atretic oocytes were significantly higher than from MII oocytes. No correlation was found between AMH expression and secretion to fertilization or embryo quality. FF of MI and GV oocytes had higher concentrations of testosterone and lower progesterone/oestradiol ratios than MII oocytes, and FF of atretic oocytes contained higher testosterone concentrations than FF of MII oocytes. AMH is highly expressed in and secreted from cumulus GC of preovulatory follicles containing premature and atretic oocytes. Anti-Müllerian hormone (AMH) is produced in the female exclusively by granulosa cells. AMH has recently been shown to be one of the most important markers of ovarian reserve and it is highly associated with ovarian follicular development. This study investigates AMH expression and secretion from cumulus granulosa cells (GC) and steroidogenesis in the follicular fluids (FF) with relation to oocyte maturational stages, and fertilization capacity in large preovulatory follicles. We conducted a prospective study with 53 ovulatory women undergoing intracytoplasmic sperm injection. FF and cumulus GC from 140 large preovulatory follicles were individually obtained during oocyte retrieval. The main outcome measures were oocyte maturation, fertilization and embryo quality. FF were assayed for AMH, progesterone, 17β-oestradiol and testosterone. Cumulus GC were assayed for AMH mRNA expression. AMH mRNA expression in cumulus GC and AMH concentrations in FF of preovulatory follicles containing premature oocytes (germinal vesicle (GV) and metaphase I (MI)) were significantly higher than preovulatory follicles containing mature oocytes (MII oocytes). In addition, FF AMH concentrations of atretic oocytes were significantly higher than FF AMH of MII oocytes. No correlation was found between AMH expression and secretion for fertilization or embryo quality. FF of preovulatory MI and GV oocytes had higher levels of testosterone and lower progesterone/oestradiol ratios than MII oocytes, and FF of atretic oocytes contained higher testosterone levels than FF of MII oocytes. This study shows that AMH is highly expressed in and secreted from cumulus GC of preovulatory follicles containing premature and atretic oocytes.

GnRH agonist vs. hCG for triggering of ovulation--differential effects on gene expression in human granulosa cells.

Objective To investigate the mRNA expression of genes related to steroidogenesis and OHSS in granulosa cells (GCs) of patients triggered with GnRH agonist compared to patients triggered with hCG. Design Mural GCs were obtained at the time of oocyte retrieval and gene expression was analyzed using quantitative real time RT-PCR. Settings Single center, case control study. Patient(s) 24 women who were treated with GnRH agonist or hCG for triggering of ovulation. Interventions GC collection. Main Outcome Measure(s) The expression of genes related to steroidogenesis and OHSS in mural GCs Results The fertilization rate was similar in the two groups. The mRNA expression of CYP19A1 (0.50 vs 1, arbitrary unit), CYP11A1 (0.6 vs. 1) and 3 beta hydroxysteroid-dehydrogenase (0.39 vs 1) was significantly lower in the GnRH group. The expression of VEGF (0.74 vs. 1) and inhibin β B (0.38 vs 1) was lower in the GnRH analog triggered group. Conclusion Expression of genes related to steroidogenesis is lower at the time of oocyte retrieval in patients triggered with GnRH agonist. The decreased expression of VEGF and inhibin β B in the GnRH agonist group can explain the mechanism of early OHSS prevention.

Does BPA alter steroid hormone synthesis in human granulosa cells in vitro

STUDY QUESTION Does Bisphenol A (BPA) impair steroid hormone production in human luteinized granulosa cells in vitro? SUMMARY ANSWER At supra-physiological concentrations, BPA alters progesterone and estradiol synthesis in vitro and significantly reduces the mRNA and protein expression levels of three genes encoding steroidogenesis enzymes. WHAT IS KNOWN ALREADY In IVF patients, the effects of BPA exposure on cycle outcome are controversial. Previous animal studies have shown that granulosa cell steroid hormone synthesis is compromised after BPA exposure, but their findings have been difficult to replicate in humans due, in part, to the low availability of discarded biological material. STUDY DESIGN, SIZE, DURATION Luteinized granulosa cells obtained from 44 fertile and infertile patients undergoing in vitro fertilization were cultured for 48 h with different concentrations of BPA (0, 0.2, 0.02, 2.0, 20 µg/ml). PARTICIPANTS/MATERIALS, SETTING, METHODS Culture medium and total RNA extracted from the luteinized granulosa cells were examined for estradiol and progesterone levels as well as mRNA and protein expression of steroidogenesis enzymes, using enzyme immunoassays, real-time PCR and western blots. MAIN RESULTS AND THE ROLE OF CHANCE Treatment of granulosa cells with 2 or 20 µg/ml BPA for 48 h resulted in significantly lower progesterone biosynthesis (P < 0.005 and <0.001, respectively). Estradiol production was significantly altered only after incubation with 20 µg/ml of BPA (P < 0.001). These concentrations also significantly reduced the mRNA levels of 3β-hydroxysteroid dehydrogenase (3β-HSD), CYP11A1 and CYP19A1 without affecting StAR and 17β-hydroxysteroid dehydrogenase mRNA expression. Similarly, 3β-HSD, CYP11A1 and CYP19A1 protein levels were reduced after administration of 20 µg/ml BPA. Lower BPA concentrations similar to, and up to 100 times, the concentrations measured in human follicular fluid, serum and urine did not alter steroidogenesis in primary granulosa cell cultures. LIMITATIONS, REASONS FOR CAUTION This was an in vitro study investigating the effects of acute exposure (48 h) of BPA on discarded material. As such, the model may not accurately reflect the effect of BPA on the physiological events of follicular steroid hormone synthesis in vivo. WIDER IMPLICATIONS OF THE FINDINGS Our results show that in vitro exposure to BPA at low doses does not affect granulosa cells steroidogenesis. Combined with recent in vivo studies, these data can be reassuring but further studies are needed to assess the effects of chronic exposure to BPA on ovarian steroidogenesis. STUDY FUNDING AND COMPETING INTERESTS This study was supported by grant number 1936/12 from the Israeli Science Foundation (ISF). The authors have no conflict of interest.

Expression and regulation of sFRP family members in human granulosa cells

Follicular development and ovulation are major processes in the reproductive system. Understanding their complexity is important to female fertility treatments and the control of reproductive processes. Wnt signaling pathway components were shown to be involved in reproduction in animal models. The secreted frizzled-related protein-4 (sFRP4), a potential modulator of Wnt4 signaling pathway, was shown to be induced by LH in rodents and expressed in the corpus lutea, but the pattern of its expression in human ovaries remains unknown. We evaluated the expression pattern of sFRP4 and other sFRP family members in human mural and cumulus granulosa cells (GCs), as well as their regulation by LH/hCG. GCs were obtained from follicles aspirated during in vitro maturation and IVF procedures. GCs were also plated and grown in culture. We showed that the human sFRP4 expression decreases as follicles grows to the preovulatory stage and its expression was higher in cumulus GCs than in mural GCs. Interestingly, LH/hCG stimulation of GCs in vivo and in culture resulted in decreased expression of sFRP4. Of the other sFRP family members, sFRP5 expression was found in mural and cumulus GC in vivo and was shown to be induced by LH/hCG in vitro and in vivo. In summary, sFRP4 is expressed in human GCs and its expression declines during late antral follicular growth. sFRP4 expression is also inhibited by LH/hCG, unlike its rodent homolog. In human GC, sFRP5 may substitute the role of sFRP4 in mouse GC.

Progesterone antagonist, RU486, represses LHCGR expression and LH/hCG signaling in cultured luteinized human mural granulosa cells

Abstract Progesterone, the main steroid synthesized by the corpus luteum (CL), prepares the uterus for implantation, maintains the CL survival, and induces progesterone auto-secretion. However, the molecular mechanisms involving the progesterone auto-secretion pathways at the luteal phase are not fully understood, especially in humans. We aim to study the molecular mechanism of the progesterone pathway in human granulosa cells. Our model system consists of luteinized human-mural-granulosa-cells (hmGCs) obtained from follicles aspirated during in vitro fertilization (IVF) procedures. hmGCs were seeded in culture and were subjected to different hormonal treatments. mRNA levels were analyzed by quantitative real-time PCR (qRT-PCR). Progesterone levels were measured by enzyme immunoassay (EIA). We show that exposure of luteinized hmGCs to the progesterone receptor antagonist, RU486 (mifepristone), resulted in inhibition of LHCGR, LH/hCG target genes and progesterone secretion. Exposure of hmGCs to medium that was incubated with hmGCs for 4 d – conditioned medium (CM), which contain 150 ± 7.5 nM progesterone, resulted in induction of LHCGR and LH/hCG target genes, which was blocked by RU486. In addition, RU486 inhibited some of the progesterone biosynthesis pathway genes. Our results revealed a novel mechanism of the progesterone antagonist pathway in the luteal granulosa cells and emphasis the fundamental role of progesterone in the early luteal phase.