[Show abstract][Hide abstract] ABSTRACT: In normal ovarian function a controlled angiogenesis is essential. Several growth factors are involved in this process, such as the vascular endothelial growth factor (VEGF) and nerve growth factor (NGF). The angiogenesis process in the normal ovary is a tightly controlled process that occurs in each ovarian cycle. Also, angiogenesis is critical for ovarian cancer development and it is responsible for tumor spread, metastasis and its peritoneal dissemination. Ovarian cancer is the fifth leading cause of cancer death in women and it is distinguished as the most lethal gynecologic cancer. In recent years angiogenesis has been given considerable attention in order to identify targets for developing effective anti-tumor therapies. Several molecules have been reported to promote angiogenesis, such as platelet-derived growth factor (PDGF) and its receptors, the angiopoietin/Tie ligand/receptor system and fibroblast growth factor (FGF). Primarily, VEGF has been identified to play key roles in driving angiogenesis. The above-mentioned molecules are candidate drug targets. Used in combination with other treatments, anti-angiogenic therapies have managed to reduce disease progression. The present review is focused in NGF and its high affinity receptor tyrosine kinase A (TRKA). The expression of VEGF, proliferation and the angiogenesis process in ovarian cancer is importantly induced by NGF, among other molecules.
Journal of Ovarian Research 08/2014; 7(1):82. · 2.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Women with Polycystic Ovary Syndrome (PCOS) show high prevalence of endometrial hyperplasia and adenocarcinoma. Endometrial proliferation is increased, evaluated by high levels of Ki67 (cell cycle marker) and low levels of p27 (negative regulator of cell cycle). Nevertheless, endometrial changes in cyclin D1 (positive regulator of cell cycle) in PCOS-women are not described. Androst-5-ene-3β,17β-diol (androstenediol), steroid with estrogenic activity present in endometria, could be related to increased endometrial cell proliferation. The objective of this study was to determine protein content of cyclin D1 and androstenediol levels in endometria from PCOS and control-women and to evaluate the possible mechanism favoring cell proliferation associated with hormonal characteristics of patients. Therefore, cyclin D1 protein content in PCOS-women and control-endometrial tissue were assessed by western blot and immunohistochemistry. The androstenediol levels were evaluated by ELISA. To further analyze the effect of steroids (androstenediol, 17β-estradiol, testosterone) in cell proliferation, levels of proteins cyclin D1, p27 and Ki67 were evaluated in an in vitro model of stromal endometrial cells T-HESC and St-T1b. An increase in cyclin D1 and androstenediol was observed in tissues from PCOS-women relative to control group (p<0.05). In the in vitro model, androstenediol exerted increase in cyclin D1 (p<0.05) and a decrease in p27 protein level (p<0.05), while Ki67 in St-T1b cells increased under this stimulus (p<0.05). Testosterone produces opposite effects in the levels of the above markers (p<0.05). Therefore, the hormonal imbalance associated with this syndrome could alter endometrial tissue homeostasis, promoting cell proliferation. Androstenediol is a molecule that could be involved by stimulating proliferation, whereas testosterone elicits a role of cell cycle repressor.
[Show abstract][Hide abstract] ABSTRACT: Polycystic ovary syndrome (PCOS) is a common hyperandrogenic disorder associated with insulin resistance. Insulin exerts its metabolic function by activating the PI3K/Akt pathway and favoring glucose uptake. Caveolin-1 is a scaffolding protein which increases insulin receptor (IR) stability. Alternatively, activation of IR increases caveolin-1 phosphorylation on tyrosine-14. Furthermore, endometrial tissue from PCOS patients is proposed to be insulin resistant; however, the particular role of testosterone in modulating the metabolic effects of insulin remains unexplored in endometrial stromal cells. To evaluate whether androgens modulate the response to insulin, T-HESCs cells were stimulated with 100 nM testosterone for 24 h and changes in the protein levels of caveolin-1, IR, and Akt were determined by Western blotting (WB). After testosterone treatment, the consequences of acute insulin stimulation were evaluated by WB analysis of phospho-S473Akt and phospho-Y14Caveolin-1, as well as by measuring glucose incorporation analyzing 2-deoxyglucose (2-DOG) uptake. For cells pretreated with testosterone, higher IR, IRS-1, and caveolin-1 protein levels compared with control conditions were detected. However, in testosterone treated cells acute insulin stimulation did not increase phospho-S473Akt and phospho-Y14caveolin-1 levels and reduced 2-DOG uptake was observed compared to control cells. Our results suggest that testosterone may have a detrimental role on the metabolic effects of insulin in endometrial stromal cell cultures. Thus, the high androgen levels in patients with PCOS may favor insulin resistance observed in endometria from these women.
Hormone and Metabolic Research 05/2013; · 2.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: STUDY QUESTION: Does treatment with the insulin sensitizer metformin modify the levels and activation of proteins related to the expression of the insulin-dependent glucose transporter (GLUT4), such as adenosine monophosphate-activated protein kinase (AMPK) and myocyte enhancer factor 2A (MEF2A), in endometria from hyperinsulinemic hyperandrogenemic polycystic ovary syndrome (PCOS h-Ins) patients? SUMMARY ANSWER: In PCOS h-Ins patients, metformin increases endometrial levels of GLUT4 mRNA and protein levels by normalizing the quantity and activation of molecules that regulate GLUT4 expression to healthy values. These changes could improve endometrial metabolic function. WHAT IS ALREADY KNOWN: PCOS is an endocrine-metabolic disorders closely associated with insulin resistance. In particular, the insulin signaling pathway is impaired in endometria from these patients and the concentration of GLUT4, as well as the molecules involved in its translocation to the cell surface, is decreased. However, there are limited data about the mechanisms that regulate the GLUT4 expression in the endometria and the effect of metformin on them. STUDY DESIGN, SIZE AND DURATION: This is a case-control study in the setting of a research unit, approved by the Ethical Committees of our institution. The groups whose endometria were studied were PCOS h-Ins (n = 8); PCOS patients with hyperandrogenemia hyperinsulinemia taking only metformin for at least 3 months (PCOS-MTF, n = 8) and healthy fertile women at the time of hysterectomy because of benign pathology as controls (CE, n = 8). PARTICIPANTS/MATERIALS, SETTING, METHODS: Steroids and sex hormone-binding globulin were measured and glucose and insulin levels were evaluated during an oral glucose tolerance test. Protein levels for αAMPK (catalytic subunit of AMPK), phosphorylated (p)-AMPKαThr(172) (activating phosphorylation site), MEF2A, p-MEF2AThr312 (activating phosphorylation site) and GLUT4 were assessed by western blot and immunohistochemistry. In addition, GLUT4 gene expression was evaluated by RT-PCR. MAIN RESULTS AND THE ROLE OF CHANCE: We found significantly lower levels of MEF2A and p-MEF2AThr312 in PCOS h-Ins compared with CE endometria (P < 0.05). Also, we detected lower levels of p-AMPKαThr(172) in PCOS h-Ins endometria compared with the PCOS-MTF group (P < 0.05). The ratios of phospho-AMPK/total AMPK and phospho-MEF2A/total MEF2A were significantly increased in the PCOS-MTF compared with the PCOS h-Ins group (P < 0.05). The RT-PCR experiments showed lower levels of GLUT4 mRNA transcripts in PCOS h-Ins compared with PCOS-MTF-treated group (P < 0.05), the protein levels of GLUT4 were decreased in a similar way. LIMITATIONS, REASONS FOR CAUTION: The limited number of patients included in this study who presented large clinical variability. Therefore, it would be necessary to recruit a greater number of patients to minimize our data dispersion in order to prove the clinical benefits of metformin described by others. WIDER IMPLICATIONS OF THE FINDINGS: Since the insulin sensitizer metformin increases the expression of the GLUT4, it may improve endometrial physiology in PCOS patients and, therefore, promote better reproductive outcomes. These results suggest that in PCOS patients, metformin may act directly at the endometrial level and decrease insulin resistance condition by increasing the expression of GLUT4 and, in this way, indirectly restore endometrial function. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by Fondo Nacional de Desarrollo Científico y Tecnológico (grant number 1095127 to M.V.). None of the authors has any conflict of interest to declare.
[Show abstract][Hide abstract] ABSTRACT: Endometrial tissue of patients with polycystic ovary syndrome (PCOS) shows an impaired expression of insulin signaling molecules. Tyrosine phosphorylation of the insulin receptor (IR) by insulin promotes glucose uptake by activating the PI3K/Akt pathway. IR stability and function depend on the presence of the protein caveolin-1. Activation of IR increases phosphorylation of Y14caveolin-1. Since the endometrium of PCOS patients is proposed to be insulin resistant, we evaluated the phosphorylation of IR and caveolin-1 in endometria of patients with insulin resistance (PCOSE-IR) compared to controls (CE). To explore the mechanism associated with this condition, cultured endometrial cells (T-HESC) were exposed to high glucose (25 mM, 24 h), an experimental condition that leads to insulin resistance in other cell types. Endometrial protein levels of phospho-Y972IR, phospho-Y14caveolin-1 and caveolin-1 were determined by Western blotting. In cultured cells, protein levels of caveolin-1, IR, and Akt were evaluated by Western blotting. After acute insulin stimulation, phospho-S473Akt, phospho-Y14caveolin-1, and 2-deoxyglucose (2-DOG) uptake were determined. PCOSE-IR samples showed high protein levels of caveolin-1, but reduced phospho-Y14caveolin-1 compared to CE. No differences were observed for phospho-Y972IR between both groups. Cells pretreated with glucose showed a reduction in protein levels of IR and caveolin-1 and were unable to increase 2-DOG uptake, phospho-S473Akt and phospho-Y14caveolin-1 after insulin stimulation. In conclusion, in PCOSE-IR the impaired phosphorylation of IR downstream molecules such as phospho-Y14caveolin-1 suggests a diminished insulin sensitivity in endometria, condition that could be supported in vitro by the ability of T-HESCs to become insulin resistant when they are exposed to high glucose.
Hormone and Metabolic Research 12/2012; · 2.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Epithelial ovarian cancer is highly angiogenic and high expression of Nerve Growth Factor (NGF), a proangiogenic protein. Calreticulin is a multifunctional protein with anti-angiogenic properties and its translocation to the tumor cell membrane promotes recognition and engulfment by dendritic cells. The aim of this work was to evaluate calreticulin expression in human normal ovaries, benign and borderline tumors, and epithelial ovarian cancer samples and to evaluate whether NGF regulates calreticulin expression in human ovarian surface epithelium and in epithelial ovarian cancer cell lines. Calreticulin mRNA and protein levels were analyzed using RT-PCR, Western blot and immunohistochemistry in 67 human ovarian samples obtained from our Institution. Calreticulin expression induced by NGF stimulation in cell lines was evaluated using RT-PCR, Western blot and immunocytochemistry. We found a significant increase of calreticulin mRNA levels in epithelial ovarian cancer samples as compared to normal ovaries, benign tumors, and borderline tumors. Calreticulin protein levels, evaluated by Western blot, were also increased in epithelial ovarian cancer with respect to benign and borderline tumors. When HOSE and A2780 cell lines were stimulated with Nerve Growth Factor, we found an increase in calreticulin protein levels compared to controls. This effect was reverted by GW441756, a TRKA specific inhibitor. These results suggest that NGF regulates calreticulin protein levels in epithelial ovarian cells through TRKA receptor activation.
Hormone and Metabolic Research 07/2012; 44(8):639-43. · 2.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Due to its ability to induce vascular endothelial growth factor expression and proliferation, migration, and vasculogenesis of endothelial cells, nerve growth factor (NGF) has been considered as an angiogenic factor in epithelial ovarian cancer (EOC). In this work, we evaluated the angiogenic and proliferative mRNA expression profiles of EOC and addressed the responsiveness of EOC explants to NGF stimulation. Twenty EOC samples were obtained from Obstetrics and Gynecology Department, University of Chile's Clinical Hospital. Global gene expression profiles of selected poorly differentiated serous EOC samples were obtained with DNA oligonucleotide microarrays. In addition, EOC explants were subjected to NGF stimulation and levels of p-AKT, BAX, BCL2, Ki-67, c-MYC, and FOXL2 proteins were determined by immunohistochemistry. Results showed that mRNAs coding for specific transcriptional regulators and antiapoptotic components of the NGF signaling pathway were upregulated in EOC cells. At the protein level, key members of the NGF pathway including p-AKT, BCL2/BAX, Ki-67, and c-MYC were found increased, while FOXL2 was decreased in response to NGF stimulation. These findings strongly suggest that NGF stimulates cellular proliferation of human EOC.
Hormone and Metabolic Research 03/2012; 44(9):656-61. · 2.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Polycystic Ovary Syndrome (PCOS) is an endocrine-metabolic disorder commonly associated with insulin resistance (IR). Previous studies indicate about the expression of molecules involved in the insulin pathway in endometria of women with PCOS-IR. Therefore, the aim of the present study was to evaluate the effect of insulin and testosterone in the expression of these proteins in the endometria and immortal endometrial stromal cell line (T-HESCs).
We examined the protein levels of Munc18c, PKC zeta, phospho-PKC Zeta, and Syntaxin-4. Protein levels were assessed by Western Blot and/or immunohistochemistry in proliferative endometria (NPE = 6) and in PCOS endometria with insulin resistance (PCOSE-IR = 6). We also evaluated whether high concentrations of insulin (100 nM) and/or testosterone (100 nM), during a 24 h stimulatory period, affected the expression of these proteins in an immortal endometrial stromal cell line (T-HESCs). Once stimulated, proteins were extracted from cells and were assessed by Western Blot analysis. Immunocytochemistry was performed to detect AR in T-HESC cells.
Western Blot data showed decreased expression (p < 0,05) of Munc18c and phospho-PKC Zeta in PCOS-IR endometria (PCOSE-IR) with respect to the control (NPE). In the in vitro study, Western Blot analysis showed decreased levels of Munc18c, PKC Zeta and phospho-PKC Zeta with the different hormonal treatments when compared to the control condition (no hormonal stimulation) (p < 0,05). The AR was present in the endometrial stromal cell line (T-HESC).
The conditions of hyperinsulinism and hyperandrogenism present in PCOS-IR patients modulate the expression and/or phosphorylation of the proteins involved in the insulin pathway at the endometrial level. These data extend to the T-HESCs cells results, where insulin and testosterone exert an effect on both the expression and phosphorylation of proteins present in the pathway.
Reproductive Biology and Endocrinology 03/2012; 10:17. · 2.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To evaluate the role of trkA receptor as a potential tumor marker in serous epithelial ovarian cancer and its relationship with the angiogenic factors expression as vascular endothelial growth factor (VEGF) and nerve growth factor (NGF). Additionally, to examine whether NGF and VEGF secreted by epithelial ovarian cancer (EOC) explants and from epithelial ovarian cancer cell line (A2780) are involved in the process of angiogenesis, such as cellular proliferation, migration and differentiation of the human endothelial cell line (EA.hy926).
The mRNA levels of VEGF, NGF and trkA receptors were measured using PCR in 60 ovarian samples. Cellular localization and semi-quantitative estimation of VEGF, NGF, total trkA and p-trkA was performed using IHC in epithelial cells. NGF, total trkA and p-trkA protein were also evaluated in endothelial cells from the same tissues. Human endothelial cell line EA.hy926 was cultured with conditioned media obtained from both EOC explants and from the A2780 cell line, with or without NGF stimulus.
Significantly higher levels of NGF, total trkA and p-trkA protein expressions were observed in epithelial and endothelial cells in poorly differentiated EOC versus normal ovary. Interestingly, the p-trkA receptor expression level showed the most significant difference and its presence was only found in borderline tumor and EOC samples indicating the importance of trkA receptor in EOC as a potential tumor marker. A significant increase in proliferation, migration and differentiation of EA.hy926 cells was observed with NGF, and this effect was significantly reverted when NGF was immuno-blocked and when a trkA inhibitor was used, showing that NGF is an important angiogenic factor in EOC by activating its trkA receptor.
These results indicate that p-trkA may be considered as a new potential tumor marker in EOC, and that NGF may also act as a direct angiogenic factor in EOC.
[Show abstract][Hide abstract] ABSTRACT: The changes in endometrial homeostasis found in women with polycystic ovarian syndrome (PCOS) could be associated with alterations in the intracrine metabolism of steroid hormones. The uptake of dehydroepiandrosterone-sulphate (DHEA-S), precursor of the intracrine pathway, is achieved by transporters, such as organic anion transporter polypeptides (OATPs), and molecules with oestrogenic activity, such as androst-5-ene-3beta,17beta-diol (androstenediol), can be generated. We aimed to determine androstenediol generation and the expression of OATPs in human endometria throughout the menstrual cycle and in endometria from PCOS women. Endometrial samples were obtained from control women in the proliferative phase (control endometria (CEp), n=7), secretory phase (CEs, n=7), and from PCOS patients (PCOSEp, n=7). The mRNA levels of OATP-B, OATP-D and OATP-E were measured by reverse transcriptase polymerase chain reaction (RT-PCR) and protein levels of OATP-E by immunofluorescence; 3beta-hydroxysteroid dehydrogenase (HSD) by immunohistochemistry/Western blot; the metabolism of DHEA to androstenediol was evaluated by thin layer chromatography-high-performance liquid chromatography (TLC-HPLC). Lower levels of OATP-E transcript were obtained in PCOSEp (p<0.05) compared with CEp, while OATP-E protein levels (p<0.05) and DHEA conversion to androstenediol (p<0.01) were higher in PCOSEp. Lower 3beta-(hydroxysteroid dehydrogenase) HSD protein levels were found in PCOSEp (p<0.05) (Western blot, immunohistochemistry). These results reveal a higher capacity of the endometria from PCOS women to metabolise DHEA to androstenediol, which, coupled with the high oestrogen sensitivity previously found in these endometria, may account for the increase in cell proliferation in PCOSEp already reported.
[Show abstract][Hide abstract] ABSTRACT: Polycystic ovary syndrome (PCOS) is an endocrine-metabolic disorder highly associated with insulin resistance and compensatory hyperinsulinemia. It is known that the insulin signaling pathway is impaired in endometria from PCOS hyperinsulinemic women, but no information is available about molecules associated with cell surface GLUT4 translocation. We therefore evaluated the protein levels of AS160 target molecules, Rab8A and Rab10, and the WAVE family proteins involved in the cortical-actin remodeling, Neural Wiskott-Aldrich Syndrome Protein (N-WASP) and WASP, in endometria from hyperinsulinemic PCOS women and controls.
Protein levels were assessed by western blot, immunohistochemistry and immunofluorescence in proliferative (PE = 7) and secretory (SE = 7) phase endometria from control women and in endometria from hyperinsulinemic PCOS women (PCOS h-INS = 7).
Similar levels were detected for Rab10 in the three studied groups; however, Rab8A levels decreased in SE (P < 0.05) while higher levels were obtained in PCOSE h-INS compared with PE (P < 0.05). In the normal menstrual cycle, Neural Wiskott-Aldrich syndrome protein (N-WASP) and WASP levels were increased in SE versus PE (P < 0.05), but in PCOSE h-INS, the levels were diminished compared with PE (P < 0.05).
SE is characterized by protein expression changes associated with glucose uptake. In endometria from PCOS women with hyperinsulinemia, reduced levels of WAVE family proteins could compromise the cell surface GLUT4 exposure and the consequent glucose uptake in this tissue.
Human Reproduction 11/2010; 25(11):2870-7. · 4.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fifty to seventy percent of patients with polycystic ovary syndrome (PCOS) present hyperinsulinemia. On the other hand, reports indicate that forkhead box class O 1 (FOXO1) and peroxisome proliferator-activated receptor-gamma (PPARG) are involved in the insulin signaling pathway, regulating the gene expression of SLC2A4 (GLUT4). The negative effect of FOXO1 over PPARG transcription disappears when FOXO1 is phosphorylated (p-FOXO1) and excluded from the nucleus, whereas PPARG can suppress gene expression of SLC2A4. Scarce knowledge is available in endometrium of women with PCOS and hyperinsulinemia (PCOSE h-Ins) about the role of these factors. We aimed to evaluate whether the endocrine and metabolic status of PCOS modify the levels of gene and protein expression of FOXO1, PPARG, and SLC2A4 in the endometria from hyperinsulinemic PCOS women compared with controls. In endometria from control (CE, n=7) or PCOSE h-Ins (n=7), we determined the subcellular location and protein levels of p-FOXO1Ser319 and FOXO1/FOXO4 by immunohistochemistry and western blot respectively; gene and/or protein levels of PPARG and SLC2A4 were evaluated by RT-PCR and/or western blot. Cytoplasm location for FOXO1 and p-FOXO1Ser319 was immunodetected in both groups of endometria, showing significantly higher staining in PCOSE h-Ins for these proteins (P<0.05). In PCOSE h-Ins, gene and protein levels of PPARG were significantly higher than in CE, whereas SLC2A4 mRNA was decreased (P<0.05). In conclusion, the derepression of PPARG transcription by the high levels of p-FOXO1Ser319 could partially account for the lower levels of SLC2A4 found in PCOSE h-Ins, suggesting an alteration of the endometrial function in these patients.
[Show abstract][Hide abstract] ABSTRACT: Polycystic ovary syndrome (PCOS) is an endocrine-metabolic disorder associated with insulin resistance and compensatory hyperinsulinemia. Scarce information is available on the expression of molecules involved in the insulin pathway in endometria from women with PCOS. Therefore, we examined the protein levels of insulin-signaling molecules, like insulin receptor, insulin-receptor substrate (IRS)-1, pIRS-1Y612, Akt, AS160, pAS160T642 and GLUT4 in endometria from PCOS women with or without hyperinsulinemia. Protein levels were assessed by Western blot and immunohistochemistry in 21 proliferative-phase endometria from control women (CE = 7), normoinssulinemic PCOS women (PCOSE-NI = 7) and hyperinsulinemic PCOS women (PCOSE-HI = 7). The data show no differences in the expression of insulin receptor between all groups as assessed by Western blot; however, IRS-1 and pIRS-1Y612 were lower in PCOSE-HI than controls and PCOSE-NI (P < 0.05). AS160 was detected in all analyzed tissues with similar expression levels between groups. Importantly, PCOSE-HI exhibited lower levels of pAS160T642 (P < 0.05) and of GLUT4 (P < 0.05) compared with CE. The immunohistochemistry for insulin receptor, IRS-1, Akt, AS160 and GLUT4 showed epithelial and stromal localization; IRS-1 staining was lower in PCOSE-HI (P < 0.05). In conclusion, human endometrium has the machinery for glucose uptake mediated by insulin. The diminished expression of GLUT4, as well as the lower level of pIRS-1Y612 and pAS160T642 exhibited by PCOSE-HI, suggests a disruption in the translocation of vesicles with GLUT4 to the cell surface in these patients.
Molecular Medicine 12/2009; 16(3-4):129-36. · 4.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Acquisition of ovulatory competence by antral follicles requires development of an adequate vascular supply. Although it is well established that ovarian angiogenesis is cyclically regulated by vascular endothelial growth factor (VEGF), the factors controlling VEGF production by ovarian follicles remain largely unknown. Nerve growth factor (NGF) may be one of these factors, because NGF promotes angiogenesis and synthesis of angiogenic factors in other tissues and is produced by human granulosa cells (hGCs).
The aim of the study was to determine whether NGF influences the production of VEGF by hGCs and to identify a potential signaling pathway underlying this effect.
We conducted a prospective experimental study.
hGCs were obtained from 41 women participating in the in vitro fertilization program of our institution.
Changes in VEGF mRNA after exposure to NGF were evaluated in cultured hGCs by PCR and real-time PCR. The effect of NGF on VEGF secretion was determined by ELISA. The involvement of trkA, the high affinity NGF receptor, was examined by inhibiting the receptor's tyrosine kinase activity with K252a. The contribution of an ERK1/ERK2-mediated signaling pathway was identified by detecting NGF-dependent phosphorylation of these proteins and by blocking their activity with the inhibitor U0126. Results: NGF promotes VEGF production in cultured hGCs. Blockade of trkA receptor tyrosine kinase activity blocks this effect. NGF induces MAPK-ERK2 phosphorylation, and blockade of this signaling pathway prevents the NGF-induced increase in VEGF production.
NGF promotes ovarian angiogenesis by enhancing the synthesis and secretion of VEGF from hGCs via a trkA- and ERK2-dependent mechanism.
The Journal of Clinical Endocrinology and Metabolism 06/2009; 94(8):3065-71. · 6.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of the present investigation was to study whether the endocrinological status of women bearing polycystic ovarian syndrome (PCOS) affects the endometrial in situ steroid metabolism. For this purpose, we evaluated the mRNA levels (RT-PCR), and the activity of steroid metabolic enzymes: P450 aromatase, steroid sulfatase (STS), estrogen sulfotransferase (EST) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD) in 23 samples of normal endometria (CE), 18 PCOS endometria without treatment (PCOSE), 10 specimens from PCOS women with endometrial hyperplasia (HPCOSE), and 7 endometria from patients with endometrial hyperplasia not associated to PCOS (EH). The data showed lower levels of STS mRNA for PCOSE and HPCOSE (p<0.05, p<0.01, respectively) and of EST for HPCOSE and EH compared to control (p<0.05). However, higher levels for EST mRNA were obtained in PCOSE (p<0.05) versus CE. The mRNA and protein levels for P450 aromatase were undetectable in all analyzed endometria. The relationship between the activities of STS and EST was lower in PCOSE and HPCOSE (p<0.05) versus CE. The ratio between the mRNA from 17beta-HSD type 1/type 2 was higher in PCOSE (p<0.05), whereas, a diminution in the 17beta-HSD type 2 activity was observed in PCOSE (p<0.05). These results indicate that the activity of enzymes related to the steroid metabolism in analyzed PCOSE differ from those found in the CE. Consequently, PCOSE may present an in situ deregulation of the steroid metabolism.
The Journal of Steroid Biochemistry and Molecular Biology 05/2008; 110(1-2):163-9. · 4.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Polycystic Ovary Syndrome (PCOS) is an endocrine-metabolic pathology related with infertility and recurrent miscarriage. We have previously shown that the endometrium of these patients can exhibit a potentially higher sensitivity to estrogen action, being estrogens important regulators of the cell cycle and tissue homeostasis. The effect of estrogens on tissues depends on their in situ availability, which is in part regulated by the activity of steroid metabolic enzymes within the tissues. Therefore, the objective of the present study was to analyze if the activity and/or expression of steroid metabolic enzymes in endometria from women with PCOS differ from controls. For this purpose, the activity of the enzymes was determined by using radiometric assays and the mRNA levels measured by semi-quantitative RT-PCR. Both assays were assessed in endometria obtained during mid secretory phase from control (CE, n=12) and PCOS women (PCOSE, n=11). For the statistical analyses, Mann-Whitney and Student's t-tests were used to compare CE and PCOSE, considering a p value <0.05 significantly different. The results showed an increase in the sulfatase activity in PCOS respect to control endometria (200+/-28pmol/mg vs. 115+/-13pmol/mgproth; p<0.05), in agreement with the higher mRNA levels found for the enzyme in PCOSE. In addition, a PCOSE exhibited lower activity of sulfotransferase respect to the control group (50+/-21pmol/mg vs. 124+/-10pmol/mgproth; p<0.05), whereas a higher level of 17beta-hydroxysteroid dehydrogenase type 1mRNA was found in PCOSE compared with the control tissues (p<0.05). The activity of 17beta-hydroxysteroid dehydrogenase type 2 and the mRNA levels of sulfotransferase were similar in both groups; meanwhile, the expression of aromatase was undetectable. These data indicate that the sulfatase pathway could play an important role in the local production of estrogens in PCOSE from secretory phase. This potentially higher bioavailability of estrogens in endometria from PCOS women could influence the deregulation of tissue homeostasis that we have previously reported, and could partially explain the poor reproductive performance observed in this group of patients.
[Show abstract][Hide abstract] ABSTRACT: To compare the expression of nerve growth factor (NGF) and its high-affinity receptor trkA in normal ovaries and in epithelial ovarian carcinomas. Given NGF acts as an angiogenic factor through a vascular endothelial growth factor (VEGF)-mediated mechanism in several types of tissues, we examined whether NGF regulates the expression of VEGF isoforms in epithelial ovarian cancer (EOC).
The expression and localization of NGF and tyrosine kinase receptor A (trkA) in normal ovarian samples and in ovarian cancer samples were analyzed by RT-PCR and immunohistochemistry. NGF regulates the expression of three VEGF isoforms (VEGF(121), VEGF(165) and VEGF(189)); these were examined using RT-PCR in explants of EOC and ELISA in culture media.
TrkA mRNA levels were over-expressed in ovarian cancer compared to normal ovarian samples, whereas NGF mRNA levels remained unchanged. NGF and trkA proteins were absent or found in very low levels in normal ovarian surface epithelium (OSE), whereas they were highly expressed in epithelial cells of EOC. Additionally, NGF stimulated the expression of VEGF isoforms in cancer explants. The effect was dose-dependent and inhibited by a NGF antibody and by K(252a), a trk receptor inhibitor.
The abundance of NGF and trkA receptors in epithelial cells of EOC, together with the ability of NGF to increase VEGF expression strongly suggests an autocrine role of NGF in EOC. These findings suggest that blocking neurotrophin action could be a therapeutic target in treating ovarian cancer.
[Show abstract][Hide abstract] ABSTRACT: The hormonal alterations observed in women with polycystic ovary syndrome (PCOS) may promote implantation failure as well as disruption of their endometrial homeostasis. To evaluate cell survival of mid-secretory endometrium from untreated women with PCOS, we measured the expression of apoptosis and proliferation-related proteins.
A case-control study of 11 patients with PCOS and 11 fertile women in the Hospital Research Unit was performed. Endometrial samples were obtained from PCOS women (PCOSE) and fertile healthy women (CE) during the mid-secretory phase of the menstrual cycle. Protein expressions for Akt, p-AktSer473 and p-AktThr308, Bad, p-BadSer136, Bcl-2, Bax and pro-caspase-3/caspase-3, were assessed by western blot, and Ki67 and p-histone-3 (p-H3) by immunohistochemistry.
In CE and PCOSE, a predominance of p-AktThr308 over p-AktSer473 is observed; p-BadSer136 expression is higher in PCOSE than in CE (P < 0.05). Also, Bcl-2 protein is overexpressed in PCOSE (P < 0.05), with no changes in Bax expression among the two groups, resulting in a significantly higher Bcl-2/Bax ratio in PCOSE than in CE (P < 0.05). No changes in the expression of caspase-3 are obtained between both groups of endometria. Furthermore, cell proliferation detected by the expression of Ki67 and p-H3 proteins is higher in the epithelia than the stroma of PCOSE versus CE (P < 0.05).
The abnormal tissue homeostasis exhibited by the secretory endometrium from PCOS patients with spontaneous ovulation may interfere with their endometrial receptivity.
Human Reproduction 12/2006; 21(12):3116-21. · 4.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Previous studies showed that nerve growth factor (NGF) induces the expression of functional FSH receptors (FSHR) in preantral follicles of the developing rat ovary.
The objective of this study was to determine whether NGF can affect granulosa cell (GC) function in human periovulatory follicles using intact human ovaries and isolated human GCs.
Human GCs were obtained from in vitro fertilization patients and normal ovaries from women with elective pelvic surgery for nonovarian indications. Results: In normal ovaries, NGF and trkA (NGF's high-affinity receptor) were detected by immunohistochemistry in GCs of preantral and antral follicles. NGF and trkA are also present in thecal cells of antral follicles. Both freshly collected and cultured GCs contained immunoreactive NGF and trkA in addition to their respective mRNAs. Human GCs respond to NGF with increased estradiol (E(2)) secretion and a reduction in progesterone output. Exposure of human GCs to NGF increased FSHR mRNA content within 18 h of treatment, and this effect was blocked by the trk tyrosine kinase blocker K-252a. Also, cells preexposed to NGF released significantly more E(2) in response to hFSH than cells not pretreated with the neurotropin, showing that the NGF-induced increase in FSHR gene expression results in the formation of functional FSHRs.
These results suggest that one of the functions of NGF in the preovulatory human ovary is to increase the secretion of E(2) while preventing early luteinization via an inhibitory effect on progesterone secretion. NGF stimulates E(2) secretion both directly and by increasing the formation of FSHRs.
[Show abstract][Hide abstract] ABSTRACT: Angiogenesis is a crucial process in follicular development and luteogenesis. The nerve growth factor (NGF) promotes angiogenesis in various tissues. An impaired production of this neurotrophin has been associated with delayed wound healing. A variety of ovarian functions are regulated by NGF, but its effects on ovarian angiogenesis remain unknown. The aim of this study was to elucidate if NGF modulates 1) the amount of follicular blood vessels and 2) ovarian expression of two angiogenic factors: vascular endothelial growth factor (VEGF) and transforming growth factor beta 1 (TGFbeta1), in the rat ovary.
In cultured neonatal rat ovaries, NGF increased VEGF mRNA and protein levels, whereas TGFbeta1 expression did not change. Sectioning of the superior ovarian nerve, which increases ovarian NGF protein content, augmented VEGF immunoreactivity and the area of capillary vessels in ovaries of prepubertal rats compared to control ovaries.
Results indicate that NGF may be important in the maintenance of the follicular and luteal vasculature in adult rodents, either indirectly, by increasing the expression of VEGF in the ovary, or directly via promoting the proliferation of vascular cells. This data suggests that a disruption on NGF regulation could be a component in ovarian disorders related with impaired angiogenesis.
Reproductive Biology and Endocrinology 02/2006; 4:57. · 2.41 Impact Factor