| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
RESEARCH |
Comprehensive Reproductive Medicine, Graduate School, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
Correspondence should be addressed to T Ishikawa; Email: t.ishikawa.crm{at}tmd.ac.jp
| Abstract |
|---|
|
|
|---|
| Introduction |
|---|
|
|
|---|
Androgens induced prolactin production in human endometrial stromal cells (HESCs) in vitro (Narukawa et al. 1994) and showed an inhibitory effect on the growth and the secretory activity of endometrial epithelial cells in vitro (Tuckerman et al. 2000). In addition, HOXA-10 expression, which is essential for endometrial development and uterine receptivity to implantation, was suppressed by testosterone in vitro (Cermik et al. 2003). In contrast, hydroxyflutamide (FLU), a specific androgen receptor antagonist, delayed the initiation of implantation, fetal development, and parturition in pregnant rats and suppressed decidualization in pseudo pregnant rats (Chandrasekhar et al. 1990). These reports suggest that the endometrium itself may be the target of androgens, and androgens may play important roles in human endometrium.
In addition, it has also been documented that hyperandrogenism, which is one of the cardinal features in poly cystic ovary syndromes (PCOS; The Rotterdam ESHRE/ASRM-Sponsored PCOS consensus workshop group 2004), may have an influence on the endometrium. In PCOS patients, although early pregnancy loss is one of the reproductive problems (Van der Spuy & Dyer 2004), the exact mechanism and causative factor of this problem has yet to be defined. An association between hyperandrogenism and increased incidence of miscarriage in PCOS patients was reported (Tulppala et al. 1993). Okon et al.(1998) postulated that androgens might have a detrimental effect on endometrial function, preventing effective endometrial development both in the proliferative and secretory phase. High levels of serum androgens have also been associated with recurrent miscarriages in women with or without PCOS (Okon et al. 1998, Bussen et al. 1999). On the other hand, Rai et al.(2000) reported that an elevated serum testosterone concentration was not associated with an increased miscarriage rate. The relationship between hyperandrogenism and increased incidence of miscarriage in PCOS patients is under some current controversy (Checa et al. 2005). The influences of androgens and hyperandrogenism on the endometrium need to be fully elucidated because PCOS is a common endocrinopathy in women of reproductive age (Van der Spuy & Dyer 2004).
Matrix metalloproteinases (MMPs), in part, regulate dynamic structural changes observed in the uterus throughout the menstrual cycle. In fact, MMPs play a pivotal role in embryo implantation (Xu et al. 2000) and the initiation of menstruation (Hampton & Salamonsen 1994, Marbaix et al. 1995). MMPs are grouped according to their domain structure into collagenases, gelatinases, stromelysins, and matrilysin (Sternlicht & Werb 2001). Collagenases (MMP-1, MMP-8, and MMP-13) are the only mammalian enzymes that can cleave collagen helices to yield characteristic one-quarter to three-quarter products at neutral pH (Marbaix et al. 1996). Denaturation of fibrillar collagens, which are essential components of endometrial extracellular matrix (ECM) (Aplin et al. 1988) by MMP-1, is necessary for further processing towards menstruation by strolelysins (MMP-3) and gelatinases (MMP-2; Lockwood et al. 1998). Therefore, MMP-1 appears to be important for the endometrial tissue degradation and remodeling.
The purpose of the present study is to investigate the role of testosterone and AR in the regulation of MMP-1 in HESCs in vitro using ELISA measurements and western blotting analysis. Furthermore, we compared the effect of testosterone and those of progestins (natural progesterone and medroxyprogesterone acetate (MPA)) with the regulation of MMP-1 in HESCs.
| Materials and Methods |
|---|
|
|
|---|
HESC culture and steroid hormone treatments
Tissue culture reagents and steroid hormones were purchased from Sigma unless otherwise specified. HESCs were grown to confluence in a 37 °C, 95:5 (%) air/CO2 incubators in cultured medium: phenol red free-D-MEM/F-12 (Invitrogen Corporation) containing 10% heat-inactivated and charcoal stripped fetal bovine serum (FBS; Wako, Osaka, Japan) and 1% AntibioticAntimycotic (Invitrogen Corporation). After confluency, HESCs were washed with D-PBS and treated with 0.02% EDTA and 0.25% trypsin (Invitrogen Corporation). To confirm the purity of the purified HESCs, immunocytochemical staining for vimentin, cytokeratin, and CD45 was performed using antivimentin, cytokeratin, or CD45 MAB (DakoCytomation, Glostrup, Denmark) as described previously (Tuckerman et al. 2000). The trypsinized HESCs were seeded 20x104/well in 24-well plates (Becton Dickinson) in cultured media containing 10 nM 17ß-estradiol (E2), 100 nM testosterone, or E2 + 1 to 1000 nM testosterone. A measure of 100 nM progestins (natural progesterone or MPA) or vehicle (dimethyl sulfoxide) were also added to the media instead of testosterone in order to compare the effects of testosterone with those of progestins. Furthermore, 1 µM FLU, a specific AR antagonist, was added to the media. The media were replaced every 4 days. Culture was terminated on day 8. All the collected media were centrifuged to remove cell debris and the supernatants were stored at 20 °C until MMP-1 concentration measurement. The wells were washed twice with cold D-PBS and HESCs were taken for protein preparation.
ELISA for MMP-1
The cultured media were assayed for MMP-1 levels by ELISA (Amersham Biosciences), which detected total MMP-1 (proMMP-1, active MMP-1, and MMP-1/tissue inhibitor of metalloproteinase complexes), according to the manufacturers instructions. Briefly, samples and standards were incubated in microtiter wells precoated with anti-MMP-1 antibody. After washing, a polyclonal antibody to MMP-1 was bound to the MMP-1. Any excess was removed, and then the second antibody bound to the wells was detected using donkey anti-rabbit horseradish peroxidase. The amount of peroxidase bound to each well was determined by the addition of tetramethylbenzidine (TMB) substrate. The reaction was stopped by the addition of sulfuric acid (Wako) and the resultant color was read at 450 nm in a microplate spectrophotometer by Model 450 Microplate Reader (Bio-Rad Laboratories). The concentrations of MMP-1 in samples were determined by interpolation from a standard curve and then normalized to the protein content of the HESCs. Experiments were done in quadruplicate. The sensitivity of this assay was 1.7 ng/ml, and there was no significant cross-reactivity or interference in the assay with MMP-3, MMP-2, and MMP-9 according to the manufacturers specification (Amersham Biosciences).
Protein assay and western blotting analysis
HESCs were lysed with lysis buffer (50 mM TrisHCl pH 7.5, 0.15 M NaCl, 1% Nodidet P-40, 0.1% deoxycholic acid, 10 µM phenyl methylsulphonyl fluoride, 0.5 mU/ml apoprotinin, 1 µM leupeptin, and 1 µM pepstatin) to analyze the expression of MMP-1 protein. Protein content of the HESCs was determined by Micro BCA Protein Assay Reagent Kit (Pierce, Rockford, IL, USA) according to manufacturers instructions. Samples, each containing equivalent amounts of protein, were separated by 10% SDS-PAGE and transferred onto PVDF membranes (Atto, Tokyo, Japan). After blocking with Block Ace (Dainipponseiyaku, Osaka, Japan) containing 10% FBS to prevent non-specific binding of the antibodies, the membranes were incubated with anti-MMP-1 polyclonal antibody (Sigma) (1:1000) overnight at room temperature. After washing with buffer, the membranes were sequentially incubated with horseradish peroxidase-conjugated anti-rabbit IgG antibody (1:5000) (Amersham Biosciences). The bound antibodies were detected by ECL (Amersham Biosciences) in accordance with the recommended procedure. Quantification was performed by computerized optimal densitometric scanning of images (National Institutes of Health image program), and then normalized using ß-actin protein as internal standard.
RNA extraction and RT-PCR
Total RNA was isolated from HESCs using RNeasy mini kits (Qiagen) in accordance with the manufacturers instructions. The quantity of extracted total RNA was determined by spectrophotometry at 260 and 280 nm. CDNA was prepared from 5 µg DNase-treated RNA using the SuperScript First-Strand Synthesis System (Invitrogen Corporation), and one-tenth of the mixture was treated with RT and used as a template for PCR. The primer sequences for human AR were designed according to the published cDNA sequences (Lovely et al. 2000). The sense 5'-AGATGGGCTTGACTTTCCCAGAAAG-3' and the antisense 5'-ATGGCTGTCATTCAGTACTCCTGGA-3' primers were used to amplify a 545 bp fragment. The housekeeping gene glyceraldehyde-3-phosphate dehydrogenase was also amplified using the following primers: 5'-TGAAGGTCGGAGTCAACGGATTTG-3' and 5'-GCGCCAGTAGAGGCAGGGATGATG-3', yielding a 628 bp product. PCR amplification was carried out using a PCR core kit (Roche). Samples were amplified in a 50 µl PCR solution (10 mM TrisHCl (pH 8.3), 50 mM KCl, 1.5 mM MgCl2, 0.2 mM dNTP, and 2.5 IU Taq polymerase) with 30 cycles of the following sequential steps: denaturation at 94 °C for 1 min, annealing at 55 °C for 2 min, and extension at 72 °C for 3 min in a GeneAmp PCR System 2700 Thermal Cycler (Applied Biosystems, Foster City, CA, USA). The PCR products were subjected to 2.0% agarose gel (Takara, Tokyo, Japan) electrophoresis and visualized by ethidium bromide staining. The sequences were determined using an automated ABI Prism 310 sequencer (Perkin-Elmer, Boston, MA, USA) and compared with those of AR to confirm their identity. PCR amplification of samples without prior RT was performed as a negative control.
Statistical analysis
All experiments were repeated at least three times to ensure reproducibility of the results, and the values are shown as the mean ± S.D. when applicable. For comparison between unpaired groups, one-way ANOVA was used. Differences were considered significant for a P value less than 0.05.
| Results |
|---|
|
|
|---|
Effect of testosterone on MMP-1 secretion
Amounts of MMP-1 in cultured media were measured by ELISA. The representative results of MMP-1 concentrations in cultured media are shown in Figs 1
4![]()
![]()
. E2 had no independent effect on the amounts of MMP-1 in cultured media (Fig. 1
). Testosterone markedly suppressed the amounts of MMP-1 in a dose-dependent manner, and the concentrations of MMP-1 were significantly decreased (P < 0.05) by 100 nM testosterone when compared with control (vehicle) and E2 alone (Fig. 2
). On the other hand, amounts of MMP-1 were also significantly reduced (P < 0.05) by both 100 nM MPA and natural progesterone (Fig. 3
). Furthermore, the suppression of MMP-1 concentration by MPA was significantly greater than by natural progesterone and testosterone (P < 0.05; Fig. 3
). Thus, the secretion of MMP-1 from cultured HESCs was inhibited by testosterone as well as natural progesterone, and MPA was much more effective in MMP-1 inhibition than natural progesterone and testosterone.
|
|
|
|
|
|
|
|
| Discussion |
|---|
|
|
|---|
The roles of androgens in uterine endometrium are beginning to be investigated. It is suggested that the endometrium itself may be the target of androgens, and androgens may play important roles in human endometrium. The fact that testosterone inhibited MMP-1 production in HESCs in this study is very important, because we clarified one of the mechanisms of regulation of MMP-1, which have important roles in implantation and pregnancy.
Expression and secretion of MMPs are tightly controlled by a variety of growth factors, cytokines, oncogenic cellular transformation, tumor promoters, physical stress, and chemical agents such as steroid hormones (Woessner 1991, Nagase & Woessner 1999). This regulation occurs at the transcriptional or post-transcriptional level, and also at the protein level via their activators, their inhibitors, and their cell surface localization (Sternlicht & Werb 2001). The precise mechanism of testosterone-induced MMP-1 repression in HESCs was not reported. In the human prostate carcinoma cell line, however, MMP-1 production was inhibited by testosterone and this inhibition occurred not through AP-1 but through a family of Ets-related transcription factors (Schneikert et al. 1996). Dynamic tissue remodeling occurs as a result of alteration in extracellular matrix in prostate as well as in endometrium (Nagle et al. 1994). Further investigation of the regulatory mechanisms of the repressive effect on MMP-1 production by testosterone in HESCs is needed.
In addition, a decrease in MMP-1 induced by natural progesterone and MPA in HESCs was also demonstrated in the present study (Figs 3
and 7
). Furthermore, we demonstrated that MPA was much more effective in the decrease in MMP-1 than natural progesterone and testosterone. This greater inhibition by MPA is due to its multiple hormone profiles including progesterone, glucocorticoid, and androgenic activity. Glucocorticoid also has an inhibitory effect on MMP-1 production in some cell types (Jonat et al. 1990, Yang-Yen et al. 1990). However, the MPA-induced decrease in MMP-1 in HESCs was mainly due to its androgenic activity, because FLU recovered the repressive effect of MPA to a level similar to that induced by testosterone or natural progesterone. The repressive effects of progestins on the production of MMP-1 in the human endometrium have been reported before (Marbaix et al. 1992, Lockwood et al. 1998). They showed inhibition of MMP-1 expression using explants of human endometrium (Marbaix et al. 1992) and cultured HESCs (Lockwood et al. 1998); however, the mechanism of the regulation on transcription of MMP-1 by progesterone is not yet understood. Progesterone may regulate MMP-1 gene via non-classical DNA sequences (Hulboy et al. 1997). Furthermore, the ligand-activated progesterone receptor may decrease the amounts of transcription factors by a direct proteinprotein interaction, resulting in a decreased binding of the transcription factors on the AP-1 site of MMP-1 promoter (Dong et al. 2002).
In conclusion, the present study demonstrated that the secretion and production of MMP-1 in HESCs in vitro are inhibited by testosterone through androgen receptors. Appropriate regulation of MMP-1 is crucial for uterine remodeling because MMP-1 plays an important role in endometrial tissue degradation that initiates menstruation. These findings indicate that androgen plays an important role in cyclic degradation and renewal of human endometrium.
| Acknowledgements |
|---|
|
|
|---|
| Footnotes |
|---|
| References |
|---|
|
|
|---|
Ajossa S, Guerriero S, Paoletti AM, Orru M & Melis GB 2002 The antiandrogenic effect of flutamide improves uterine perfusion in women with polycystic ovary syndrome. Fertility and Sterility 77 11361140.[CrossRef][ISI][Medline]
Aplin JD, Charlton AK & Ayad S 1988 An immunohistochemical study of human endometrial extracellular matrix during the menstrual cycle and first trimester of pregnancy. Cell and Tissue Research 253 231240.[ISI][Medline]
Apparao KB, Lovely LP, Gui Y, Lininger RA & Lessey BA 2002 Elevated endometrial androgen receptor expression in women with polycystic ovarian syndrome. Biology of Reproduction 66 297304.
Bussen S, Sutterlin M & Steck T 1999 Endocrine abnormalities during the follicular phase in women with recurrent spontaneous abortion. Human Reproduction 14 1820.
Cermik D, Selam B & Taylor HS 2003 Regulation of HOXA-10 expression by testosterone in vitro and in the endometrium of patients with polycystic ovary syndrome. Journal of Clinical Endocrinology and Metabolism 88 238243.
Chandrasekhar Y, Armstrong DT & Kennedy TG 1990 Implantation delay and anti-deciduogenic activity in the rat by the anti-androgen, hydroxyflutamide. Biology of Reproduction 42 120125.[Abstract]
Checa MA, Requena A, Salvador C, Tur R, Callejo J, Espinos JJ, Fabregues F & Herrero J 2005 Insulin-sensitizing agents: use in pregnancy and as therapy in polycystic ovary syndrome. Human Reproduction Update 11 375390.
Curry TE Jr & Osteen KG 2003 The matrix metalloproteinase system: changes, regulation, and impact throughout the ovarian and uterine reproductive cycle. Endocrine Reviews 24 428465.
Dong JC, Dong H, Campana A & Bischof P 2002 Matrix metalloproteinases and their specific tissue inhibitors in menstruation. Reproduction 123 621631.[Abstract]
Hampton AL& Salamonsen LA 1994 Expression of messenger ribonucleic acid encoding matrix metalloproteinases and their tissue inhibitors is related to menstruation. Journal of Endocrinology 141 R1R3.[Abstract]
Hulboy DL, Rudolph LA & Matrisian LM 1997 Matrix metalloproteinases as mediators of reproductive function. Molecular Human Reproduction 3 2745.
Jonat C, Rahmsdorf HJ, Park KK, Cato AC, Gebel S, Ponta H & Herrlich P 1990 Antitumor promotion and antiinflammation: down-modulation of AP-1 (Fos/Jun) activity by glucocorticoid hormone. Cell 62 11891204.[CrossRef][ISI][Medline]
Lockwood CJ, Krikun G, Hausknecht VA, Papp C & Schatz F 1998 Matrix metalloproteinase and matrix metalloproteinase inhibitor expression in endometrial stromal cells during progestin-initiated decidualization and menstruation-related progestin withdrawal. Endocrinology 139 46074613.
Lovely LP, Appa Rao KB, Gui Y & Lessey BA 2000 Characterization of androgen receptors in a well-differentiated endometrial adenocarcinoma cell line (Ishikawa). Journal of Steroid Biochemistry and Molecular Biology 74 235241.[CrossRef][ISI][Medline]
Marbaix E, Donnez J, Courtoy PJ & Eeckhout Y 1992 Progesterone regulates the activity of collagenase and related gelatinases A and B in human endometrial explants. PNAS 89 1178911793.
Marbaix E, Kokorine I, Henriet P, Donnez J, Courtoy PJ & Eeckhout Y 1995 The expression of interstitial collagenase in human endometrium is controlled by progesterone and by oestradiol and is related to menstruation. Biochemical Journal 305 10271030.[ISI][Medline]
Marbaix E, Kokorine I, Donnez J, Eeckhout Y & Courtoy PJ 1996 Regulation and restricted expression of interstitial collagenase suggest a pivotal role in the initiation of menstruation. Human Reproduction 11 134143.[ISI][Medline]
Mertens HJ, Heineman MJ, Theunissen PH, de Jong FH & Evers JL 2001 Androgen, estrogen and progesterone receptor expression in the human uterus during the menstrual cycle. European Journal of Obstetrics, Gynecology, and Reproductive Biology 98 5865.[CrossRef][ISI][Medline]
Nagase H & Woessner JF Jr 1999 Matrix metalloproteinases. Journal of Biological Chemistry 274 2149121494.
Nagle RB, Knox JD, Wolf C, Bowden GT & Cress AE 1994 Adhesion molecules, extracellular matrix, and proteases in prostate carcinoma. Journal of Cellular Biochemistry 19 232237.
Narukawa S, Kanzaki H, Inoue T, Imai K, Higuchi T, Hatayama H, Kariya M & Mori T 1994 Androgens induce prolactin production by human endometrial stromal cells in vitro. Journal of Clinical Endocrinology and Metabolism 78 165168.[Abstract]
Noyes RW, Hertig AT & Rock J 1950 Dating the endometrial biopsy. Fertility and Sterility 1 325.[Medline]
Okon MA, Laird SM, Tuckerman EM & Li TC 1998 Serum androgen levels in women who have recurrent miscarriages and their correlation with markers of endometrial function. Fertility and Sterility 69 682690.[CrossRef][ISI][Medline]
Rai R, Backos M, Rushworth F & Regan L 2000 Polycystic ovaries and recurrent miscarriage a reappraisal. Human Reproduction 15 612615.
Roy AK, Tyagi RK, Song CS, Lavrovsky Y, Ahn SC, Oh TS & Chatterjee B 2001 Androgen receptor: structural domains and functional dynamics after ligand-receptor interaction. Annals of the New York Academy of Sciences 949 4457.
Schneikert J, Peterziel H, Defossez PA, Klocker H, Launoit Y & Cato AC 1996 Androgen receptor-Ets protein is a novel mechanism for steroid hormone-mediated down-modulation of matrix metalloproteinase expression. Journal of Biological Chemistry 271 2390723913.
Slayden OD, Nayak NR, Burton KA, Chwalisz K, Cameron ST, Critchley HO, Baird DT & Breener RM 2001 Progesterone antagonists increase androgen receptor expression in the rhesus macaque and human endometrium. Journal of Clinical Endocrinology and Metabolism 86 26682679.
Sternlicht MD & Werb Z 2001 How matrix metalloproteinases regulate cell behavior. Annual Review of Cell and Developmental Biology 17 463516.[CrossRef][ISI][Medline]
The Rotterdam ESHRE/ASRM-Sponsored PCOS consensus workshop group 2004 Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome (PCOS). Human Reproduction 19 4147.
Tuckerman EM, Okon MA, Li T & Laird SM 2000 Do androgens have a direct effect on endometrial function? An in vitro study. Fertility and Sterility 74 771779.[CrossRef][ISI][Medline]
Tulppala M, Stenman UH, Cacciatore B & Ylikorkala O 1993 Polycystic ovaries and levels of gonadotrophins and androgens in recurrent miscarriage: prospective study in 50 women. British Journal of Obstetrics and Gynaecology 100 348352.[ISI][Medline]
Van der Spuy ZM & Dyer SJ 2004 The pathogenesis of infertility and early pregnancy loss in polycystic ovary syndrome. Best Practice & Research. Clinical Obstetrics & Gynaecology 18 755771.[CrossRef][Medline]
Woessner JF Jr 1991 Matrix metalloproteinases and their inhibitors in connective tissue remodeling. FASEB Journal 5 21452154.[Abstract]
Xu P, Wang YL, Zhu SJ, Luo SY, Piao YS & Zhuang LZ 2000 Expression of matrix metalloproteinase-2, -9, and -14, tissue inhibitors of metalloproteinase-1, and matrix proteins in human placenta during the first trimester. Biology of Reproduction 62 988994.
Yang-Yen HF, Chambard JC, Sun YL, Smeal T, Schmidt TJ, Drouin J & Karin M 1990 Transcriptional interference between c-Jun and the glucocorticoid receptor: mutual inhibition of DNA binding due to direct proteinprotein interaction. Cell 62 12051215.[CrossRef][ISI][Medline]
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |