Correlation between steroid levels in follicular fluid and hormone synthesis related substances in its exosomes and embryo quality in patients with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is an endocrine and metabolic disorder with various manifestations and complex etiology. Follicular fluid (FF) serves as the complex microenvironment for follicular development. However, the correlation between the concentration of steroid in FF and the pathogenesis of PCOS is still unclear.

METHODS

Twenty steroid levels in FF from ten patients with PCOS and ten women with male-factor infertility undergoing in vitro fertilization were tested by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in order to explore their possibly correlation with PCOS. Meanwhile, the mRNA levels of core enzymes in steroid synthesis pathway from exosomes of FF were also detected by qPCR.

RESULTS

The estriol (p < 0.01), estradiol (p < 0.05) and prenenolone (p < 0.01) levels in FF of PCOS group were significantly increased, compared to the normal group, and the progesterone levels (p < 0.05) were decreased in PCOS group. Increased mRNA levels of CYP11A, CYP19A and HSD17B2 of exosomes were accompanied by the hormonal changes in FF. Correlation analysis showed that mRNA levels of CYP11A and HSD17B2 were negatively correlated with percent of top-quality embryos and rate of embryos develop to blastocyst.

CONCLUSION

Our results suggest that increased levels of estrogen and pregnenolone in follicular fluid may affect follicle development in PCOS patients, and the mechanism is partially related to HSD17B1, CYP19A1 and CYP11A1 expression change in FF exosomes.

Effects of Etomidate on the Steroidogenesis of Rat Immature Leydig Cells

BACKGROUND

Etomidate is a rapid hypnotic intravenous anesthetic agent. The major side effect of etomidate is the reduced plasma concentration of corticosteroids, leading to the abnormal reaction of adrenals. Cortisol and testosterone biosynthesis has similar biosynthetic pathway, and shares several common steroidogenic enzymes, such as P450 side chain cleavage enzyme (CYP11A1) and 3β-hydroxysteroid dehydrogenase 1 (HSD3B1). The effect of etomidate on Leydig cell steroidogenesis during the cell maturation process is not well established.

METHODOLOGY

Immature Leydig cells isolated from 35 day-old rats were cultured with 30 μM etomidate for 3 hours in combination with LH, 8Br-cAMP, 25R-OH-cholesterol, pregnenolone, progesterone, androstenedione, testosterone and dihydrotestosterone, respectively. The concentrations of 5α-androstanediol and testosterone in the media were measured by radioimmunoassay. Leydig cells were cultured with various concentrations of etomidate (0.3-30 μM) for 3 hours, and total RNAs were extracted. Q-PCR was used to measure the mRNA levels of following genes: Lhcgr, Scarb1, Star, Cyp11a1, Hsd3b1, Cyp17a1, Hsd17b3, Srd5a1, and Akr1c14. The testis mitochondria and microsomes from 35-day-old rat testes were prepared and used to detect the direct action of etomidate on CYP11A1 and HSD3B1 activity.

RESULTS AND CONCLUSIONS

In intact Leydig cells, 30 μM etomidate significantly inhibited androgen synthesis. Further studies showed that etomidate also inhibited the LH- stimulated androgen production. On purified testicular mitochondria and ER fractions, etomidate competitively inhibited both CYP11A1 and HSD3B1 activities, with the half maximal inhibitory concentration (IC50) values of 12.62 and 2.75 μM, respectively. In addition, etomidate inhibited steroidogenesis-related gene expression. At about 0.3 μM, etomidate significantly inhibited the expression of Akr1C14. At the higher concentration (30 μM), it also reduced the expression levels of Cyp11a1, Hsd17b3 and Srd5a1. In conclusion, etomidate directly inhibits the activities of CYP11A1 and HSD3B1, and the expression levels of Cyp11a1 and Hsd17b3, leading to the lower production of androgen by Leydig cells.

Regulation of 17beta-hydroxysteroid dehydrogenase type 2, type 4 and type 5 by calcitriol, LXR agonist and 5alpha-dihydrotestosterone in human prostate cancer cells

Vitamin D seems to be involved in the control of prostate cancer cell growth. 17beta-Hydroxysteroid dehydrogenases type 2, type 4 and type 5 are enzymes which regulate intracellular concentration of active sex steroid hormones, which in turn, regulate the development, growth, and function of the prostate and play a role in the development and progression of prostate cancer. Using quantitative real-time PCR we find that calcitriol up-regulates HSD17B type 2, type 4 and type 5 in human prostate cancer LNCaP and PC3 cells but not in stromal cells. LXR agonist, TO-901317, suppresses the expression of HSD17B2 mRNA and inhibits calcitriol induced HSD17B2 expression. TO-901317 up-regulates the expression of HSD17B5 but not that of HSD17B4. 5alpha-Dihydrotestosterone up-regulates the expression of HSD17B2 and HSD17B4 but it significantly inhibits HSD17B5 expression by 70%. Calcitriol has no effect on DHT mediated expression of the three genes. The regulation of HSD17B2, HSD17B4 and HSD17B5 by ligands of LXR and VDR as well as AR in prostate cancer cells suggests a complex interaction of these signaling systems in the prostate.

Ethanolic extracts of black cohosh (Actaea racemosa) inhibit growth and oestradiol synthesis from oestrone sulphate in breast cancer cells

Extracts of black cohosh (Actaea racemosa) and soy are used as 'natural' alternatives to conventional hormone replacement therapy (HRT) and there is some evidence that soy may protect against breast cancer by inhibiting the production of active oestrogens. This study compares the action of ethanolic extracts of black cohosh (BCE) and genistein on growth and enzyme activity in MCF-7 and MDA-MB-123 breast cancer cells. BCE inhibited growth at the two highest doses tested, i.e. 50 and 100 microg/ml, whilst genistein stimulated growth in the oestrogen receptor positive (ER(+)) MCF-7 cells, but at high doses it inhibited growth in both cell lines. BCE did not affect the conversion of androstenedione to oestradiol and only the highest doses (50 and 100 microg/ml) significantly inhibited the conversion of oestrone to oestradiol in MDA cells. In contrast, BCE induced a dose-dependent inhibition of the conversion of oestrone sulphate to oestradiol in both cell lines, whilst in human granulosa lutein (GL) cells enzyme activity was only inhibited at the highest dose of BCE. Genistein had no significant effect on enzyme activity in breast cancer cells and like BCE only the highest doses (10 and 50 microM) inhibited enzyme activity in human GL cells. In vivo genistein may have growth stimulatory effects on breast tissue but BCE not only inhibits growth but inhibits the conversion of oestrone sulphate to active oestradiol, considered by some, to be the preferred pathway of oestradiol synthesis in breast tissue.

Breast cancer risk and polymorphisms in genes involved in metabolism of estrogens (CYP17, HSD17beta1, COMT and MnSOD): possible protective role of MnSOD gene polymorphism Val/Ala and Ala/Ala in women that never breast fed

Polymorphisms in genes encoding enzymes involved in estrogen metabolism are held to be candidates for associations with breast disease, since there is evidence that circulating estrogens are associated with breast cancer risk. In this study, we evaluated the frequency of different polymorphisms related with estrogen metabolism [COMT Val158Met, CYP17 (5'UTR, T27C); HSD17beta1 Gly313Ser and MnSOD Val16Ala] in a breast cancer resistant population, the Xavante Indians, and the frequencies were compared with the ones reported in other populations where breast cancer case-control studies dealing with these polymorphisms have been carried out. The data obtained showed that, apart from the MnSOD Val16Ala polymorphism where the frequency of the variant allele was much higher than that reported in other populations, all the others were within the range reported in other populations. Considering these data we carried out a case-control study in the Portuguese population (241 cases and 457 controls) in order to evaluate the potential role of this polymorphism in breast cancer susceptibility. The results obtained did not reveal a significant association between individual genotypes and breast cancer risk. However, when the population was stratified for breast feeding, it was observed that for the patients that never breast fed the presence of the variant allele (Ala) was marginally associated with a decreased risk for this pathology (adjusted OR: 0.575 (0.327-1.011). These data seem to suggest that individuals who never breast fed with MnSOD Val16Ala variant allele are at a lower risk for breast cancer, but larger studies are required to confirm these results.

Differential regulation by a peroxisome proliferator of the different multifunctional proteins in guinea pig: cDNA cloning of the guinea pig D-specific multifunctional protein 2

After our previous report on the cloning of two cDNA species in guinea pig, both encoding the same hepatic 79 kDa multifunctional protein 1 (MFP-1) [Caira, Cherkaoui-Malki, Hoefler and Latruffe (1996) FEBS Lett. 378, 57-60], here we report the cloning of a cDNA encoding a second multifunctional peroxisomal protein (MFP-2) in guinea-pig liver. This 2356 nt cDNA encodes a protein of 735 residues (79.7 kDa) whose sequence shows 83% identity with rat MFP-2 [Dieuaide-Noubhani, Novikov, Baumgart, Vanhooren, Fransen, Goethals, Vandekerckhove, Van Veldhoven and Mannaerts (1996) Eur. J. Biochem. 240, 660-666]. In parallel, we studied the effect of ciprofibrate, a hypolipaemic agent also known as peroxisome proliferator in rodent, on the expression of MFP-1 and MFP-2 (2.6 kb) in rats and guinea pigs. By Northern blotting analysis we demonstrated that three MFP-1-related mRNA species are expressed in the guinea-pig liver. The expression of two of them (3.5 and 2.6 kb) is slightly increased by ciprofibrate, whereas the 3.0 kb MFP-1 mRNA is, unlike the rat one, strongly down-regulated in guinea pigs treated with ciprofibrate. In a similar way, the hepatic expression of the guinea-pig 2.6 kb MFP-2 mRNA is also down-regulated in guinea pigs treated with ciprofibrate. These results demonstrate (1) that in contrast with the unique 3.0 kb MFP-1 rat mRNA, at least three hepatic MFP-1-related mRNA species are co-expressed in guinea pig; and (2) that, opposed to the accepted idea of non-responsiveness of the guinea pig to ciprofibrate, this drug affects MFP-1 and MFP-2 gene expression in this species. Also, the mRNA species for acyl-CoA oxidase and thiolase, two other enzymes of the peroxisomal beta-oxidation pathway that are induced severalfold in responsive species are down-regulated in guinea pig. This paper is the first, to our knowledge, reporting the down-regulation of the expression of genes encoding enzymes involved in the peroxisomal beta-oxidation of fatty acids (MFP-1) and bile acid synthesis (MFP-2) in mammals.

Expression of engineered human 17 beta-estradiol dehydrogenase in a prokaryotic system

OBJECTIVE

17 beta estradiol dehydrogenase (17 beta DH) is a model for pyridine-dependent steroid-converting enzymes. To define the structural and functional parameters of 17 beta DH, we created an expression system for production of abundant, homogeneous enzyme.

METHODS

A full-length 17 beta DH cDNA clone was engineered into the inducible expression vector pMON 5839. After induction of plasmid-bearing Escherichia coli JM109 cells, the authenticity of the recombinant human placental 17 beta DH (r17 beta DH) was evaluated.

RESULTS

Protein electrophoresis and Western blot analysis confirmed the immunologic identity of r17 beta DH with native human placental enzyme. The amino acid sequence, enzyme activity, Vmax, K(m), and kcat of r17 beta DH matched that of the native enzyme.

CONCLUSION

Prokaryotic cell lines offer the opportunity to create an unlimited supply of recombinant human placental 17 beta DH without the expense and time commitment of baculoviral or eukaryotic cell lines. We are now able to use r17 beta DH and its mutants to elucidate the mechanisms of action of this class of enzyme.

Progestin induction of 17 beta-hydroxysteroid dehydrogenase enzyme protein in the T-47D human breast-cancer cell line

Steroid regulation of 17 beta-hydroxysteroid dehydrogenase (17-HSD) was studied in the T-47D human breast-cancer cell line, using a radioimmunoassay. In addition, 3 mRNA species (2.4, 1.4, and 0.9 kb) specific for the enzyme were shown to be present in these cells. All the synthetic progestins tested (ORG 2058, R5020, medroxyprogesterone acetate) significantly increased the immunoreactive enzyme protein concentration, while other types of steroids, such as testosterone, oestradiol and dexamethasone, were ineffective. The progestin-specific induction of 17-HSD was dose-related and was maximum in about 5 days. An antiprogestin, RU 486, when used in combination with synthetic progestins, blocked the progestin-induced increase of 17-HSD concentration very effectively. A good correlation was observed in the different experiments between the enzyme activity and the immunoreactive 17-HSD concentration. We conclude that progestins induce 17-HSD in T-47D cells and that the induction occurs via an increased accumulation of enzyme protein.

Induction of estradiol dehydrogenase activity in human uterine endometrium by synthetic steroids

The effects of P and six synthetic steroids (MPA, ENT, CAP, R2323, DL and EEL) on estradiol dehydrogenase (E2DH) activity were studied in normal human uterine endometrium in vitro. The mean value of E2DH activity in the proliferative endometrium was 1.5 +/- 0.2 nmol/mg protein/h and that in the secretory endometrium was 10.2 +/- 1.1 nmol/mg protein/h. There was a 7-fold increase in the secretory phase. E2DH activity in the uterine endometrium was stable during the culture period of up to 72 h. In the proliferative endometrium, P, MPA and ENT (approximately 10(-6)M) induced E2DH activity during a 24-h incubation. CAP and R2323 had no significant effect. EEL and DL had negligible effects. In contrast, E2DH activity in the secretory endometrium was not induced further by the steroids. Therefore, in the proliferative endometrium, the elevation of E2DH activity is attributable to the progestational activity and, in the secretory endometrium, E2DH activity is not increased further by the progestational agents because it has been already activated fully by P.

Failure of progestins to induce estradiol dehydrogenase activity in endometrial carcinoma, in vitro

Estradiol dehydrogenase (E2DH) is a well-known progesterone-dependent enzyme in human endometrium, and its induction has been proposed as a means to test hormonal sensitivity of endometrial carcinoma. While administration of progestins to some patients with endometrial carcinoma resulted in increased endometrial E2DH activity, efforts to induce this enzyme, in vitro, in these tumors have been unsuccessful. The reasons for such failure were investigated in the present study. Progesterone receptor (PR) concentrations and E2DH activities were simultaneously measured in proliferative and malignant endometria under organ culture conditions. Cytoplasmic PR concentrations were determined by Scatchard plot analysis of [3H]progesterone binding in fresh samples and in tissue explants incubated in nutrient medium at 37 degrees in a humidified 5% CO2 atmosphere for various periods of time. Parallel incubations of explants with and without 500 ng medroxyprogesterone acetate per ml were carried out for monitoring E2DH induction. In proliferative endometrium, the progesterone-specific binding sites remained stable during the culture periods, and the E2DH activities were stimulated severalfold by medroxyprogesterone acetate. In contrast, the PR concentrations in carcinoma explants were undetectable after a 24-hr period, and this was associated with a lack of increase in E2DH activity. These findings provide evidence that progestin-induced endometrial E2DH activity is a receptor-mediated phenomenon. In addition, these results demonstrate clearly that the ineffectiveness of progestin to induce E2DH in endometrial cancer specimens, in vitro, is related to the instability of PR under culture conditions. It is suggested that any experiment designed to follow effects of steroids on target tissues must take into account the stability of steroid receptors under in vitro conditions.

The induction of enzyme activity in the endosperm of germinating castor-bean seeds

Endosperm extracts were prepared at various times during germination from intact castor-bean seeds and from seeds from which the embryos had been removed. The sterilized seeds were incubated either on solid water agar or on agar containing 0.3 mM-gibberellic acid. 2. Isocitrate lyase and 3-hydroxyacyl-CoA dehydrogenase had very low activities in the mature seeds, but increased 44-fold and 27-fold respectively during germination. In contrast, the extracts of mature seeds had considerable acid and alkaline lipase activity and this only increased two- to three-fold during the incubation period. 3. Incubation of the seeds with gibberellic acid accelerated the rate of appearance of isocitrate lyase and 3-hydroxyacyl-CoA dehydrogenase. It also increased the total activity attained. However, the application of hormone had, in comparison, little effect on the development of lipase activity. 4. The removal of the embryo had little influence on the development of enzyme activity in the endosperm tissue; only with isocitrate lyase was a decrease in activity observed in the absence of the embryo.

Induction of human endometrial estradiol dehydrogenase by progestins

Estradiol-17beta dehydrogenase activity in proliferative human endometrium (average of 1.5 nmole of estrone formed from estradiol/mg protein/h) was stimulated as much as as 6-fold during incubations of tissue slices in culture medium containing progesterone. Stimulation was already detectable at 7 h and the highest activity values were reached at 48-72 h of incubation in the presence of excess progesterone. Maximal stimulation was achieved with concentrations of the hormone of 0.25 mug/ml or higher. At concentrations approximately equal to midluteal plasma levels (20 ng/ml) more than 50% of the maximal response was observed. Norgestrel (17alpha-ethynyl-18-methyl-19-nortestosterone) was also effective in inducing enzymatic activity. The similarity of the effects obtained with progesterone (a possible substrate for estradiol dehydrogenase) and the synthetic progestin indicates that the stimulation of enzymatic activity was not due to substrate induction. Addition of estradiol to the culture medium had no influence on the activity of the enzyme. The induction of estradiol dehydrogenase by progesterone was inhibited by puromycin or actinomycin D. These observations indicate that progestational agents increase the rate of de novo synthesis of the enzyme. Stimulation of endometrial estradiol dehydrogenase was also observed after 2-3 day oral administration of medroxyprogesterone acetate to women in the follicular phase. In contrast, the enzymatic activity in endometrium obtained from women taking estrogens was found to be as low as in normal proliferative tissue. These in vitro and in vivo results point to progesterone as the agent responsible for the 10-fold increase in endometrial estradiol dehydrogenase activity observed during the luteal phase in menstruating women. Data obtained from superfusion studies of estrogen dynamics in endometrium indicate that changes in enzyme concentrations may play a physiologic role in the regulation of tissue levels of estradiol.