Expression Of 17β-hydroxysteroid Dehydrogenase Type Research Articles

Halogen-Based 17β-HSD1 Inhibitors: Insights from DFT, Docking, and Molecular Dynamics Simulation Studies.

The high expression of 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) mRNA has been found in breast cancer tissues and endometriosis. The current research focuses on preparing a range of organic molecules as 17β-HSD1 inhibitors. Among them, the derivatives of hydroxyphenyl naphthol steroidomimetics are reported as one of the potential groups of inhibitors for treating estrogen-dependent disorders. Looking at the recent trends in drug design, many halogen-based drugs have been approved by the FDA in the last few years. Here, we propose sixteen potential hydroxyphenyl naphthol steroidomimetics-based inhibitors through halogen substitution. Our Frontier Molecular Orbitals (FMO) analysis reveals that the halogen atom significantly lowers the Lowest Unoccupied Molecular Orbital (LUMO) level, and iodine shows an excellent capability to reduce the LUMO in particular. Tri-halogen substitution shows more chemical reactivity via a reduced HOMO–LUMO gap. Furthermore, the computed DFT descriptors highlight the structure–property relationship towards their binding ability to the 17β-HSD1 protein. We analyze the nature of different noncovalent interactions between these molecules and the 17β-HSD1 using molecular docking analysis. The halogen-derived molecules showed binding energy ranging from −10.26 to −11.94 kcal/mol. Furthermore, the molecular dynamics (MD) simulations show that the newly proposed compounds provide good stability with 17β-HSD1. The information obtained from this investigation will advance our knowledge of the 17β-HSD1 inhibitors and offer clues to developing new 17β-HSD1 inhibitors for future applications.

Estrogen-related receptor γ regulates expression of 17β-hydroxysteroid dehydrogenase type 1 in fetal growth restriction

IntroductionEstrogen-related receptor γ (ERRγ) and 17β-hydroxysteroid dehydrogenase type 1 (HSD17B1) have important roles in cell invasion and in the proliferation of many types of cancer cells. However, it remains unknown whether ERRγ and HSD17B1 contribute to abnormal placental structure and dysfunction which characterize fetal growth restriction (FGR). Therefore, the aim of this study was to investigate the expression profiles of ERRγ and HSD17B1 in placenta tissues affected by FGR and to examine a possible molecular mechanism by which ERRγ is able to regulate HSD17B1 during development of FGR. MethodsPlacenta tissues were collected from women affected by FGR (n = 28) and from women with appropriately gestational age (AGA) (n = 30). Relative mRNA and protein levels of ERRγ and HSD17B1 in both groups were assessed by quantitative real-time PCR, immunohistochemistry, and Western blot analyses. The effect of ERRγ on trophoblast function and its associated mechanistic details were studied in the trophoblast cell line, HTR-8/SVneo, which was transfected with small interfering RNA (siRNA) targeting ERRγ. ResultsBoth mRNA and protein levels of ERRγ and HSD17B1 were significantly lower in FGR placentae (P < 0.05). When ERRγ expression was knocked down in HTR-8/SVneo cells with siRNA, invasion and proliferation were inhibited. In addition, HSD17B1 expression was significantly decreased. In dual luciferase reporter assays, ERRγ stimulated transcription of HSD17B1 by targeting the ERRγ response element within its 5′-flanking promoter region. DiscussionAberrant ERRγ expression may contribute to the pathogenesis of FGR by regulating the transcriptional activity of HSD17B1.

High Expression of 17β-hydroxysteroid Dehydrogenase Type 2 is Associated with a Better Prognosis in Urothelial Carcinoma of the Urinary Tract.

Object: To identify associations between 17β-hydroxysteroid dehydrogenase type 2 (HSD17B2) expression and clinicopathological variables and prognoses in patients with urothelial carcinoma of the urinary tract.Materials and Methods: We analyzed one public transcriptome dataset (GSE31684) from the Gene Expression Omnibus. HSD17B2 showed the highest log2-transformed fold-change in expression, and it was therefore further analyzed. We enrolled 340 upper urinary tract and 295 urinary bladder tissue samples that were obtained from patients with urothelial carcinoma between 1996 and 2004 to evaluate the expression of HSD17B2 using immunohistochemistry. The endpoints were disease-specific survival and metastasis-free survival. Univariate and multivariate analyses were performed to assess the relationships between HSD17B2, survival and clinicopathological parameters.Results: High expression of HSD17B2 was significantly associated with better clinicopathological parameters, including the following parameters in urothelial carcinoma of upper urinary tracts: Ta (non-invasive papillary carcinoma) and T1 (invaded subepithelial connective tissue) disease, without nodal metastasis, without vascular invasion, without perineal invasion and with a low histological grade, and the following parameters specifically in urothelial carcinoma of the urinary bladder: Ta (noninvasive papillary carcinoma) and T1 (invaded into the lamina propria but not into the muscularis propria) disease, without nodal metastasis (all P<0.05). Additionally, HSD17B2 high expression predicted a better prognosis, including improved disease-specific survival and metastasis-free survival in urothelial carcinomas of the urinary tract system.Conclusions: High expression of HSD17B2 is associated with a better prognosis and is therefore a prognostic biomarker that can be used to predict favorable survival in patients with urothelial carcinoma of the urinary tract system.

Expression of 17β-hydroxysteroid dehydrogenase type 2 is associated with some clinicopathological features in gastric cancer

In most populations, gastric cancer (GC) incidence is higher in men than in women, which may suggest the role of sex steroid hormones in gastric cancerogenesis. Both, androgens and estrogens can be synthetised in peripherial tissues. This process is controlled by expression of steroidogenic enzymes. Therefore, we evaluate the 17β-hydroxysteroid dehydrogenase type 2 (HSD17B2) transcript and protein levels in gastric tumoral and nontumoral tissue. We also determined the association between HSD17B2 transcript and protein levels and some clinicopathological features in GC. We found significantly decreased levels of HSD17B2 transcript (P=0.00072) and protein (P=0.00017) in primary tumoral tissues of GC patients, as compared to nontumoral tissues. In patients above 60years of age the amounts of HSD17B2 transcript (P=0.00044) and protein (P=0.00027) were significantly lower in tumoral than nontumoral tissues. Similarly, lower HSD17B2 levels, both in terms of the transcript and protein, were observed in tumoral tissues of male (P=0.013, P=0.0014), patients stomach (P=0.0062, P=0.045) and cardia (P=0.02, P=0.02) site of tumor, T3 (P=0.018, P=0.014) depth of invasion, N0 (P=0.017, P=0.045) lymph node metastasis, G3 (P=0.0027, P=0.014) malignancy grade. We also observed significantly reduced level of HSD17B2 transcript in tumoral tissue specimens of females (P=0.014), T4 depth of invasion (P=0.02), N3 lymph node metastasis (P=0.037) and G2 malignancy grade (P=0.045). Furthermore, diffuse GC histological types were associated with lower HSD17B2 protein level (P=0.024) than nontumoral tissues. We demonstrated that HSD17B2 transcript and protein levels are linked to some clinicopathological features in GC.

Expression of steroidogenic enzymes in human sebaceous glands.

Androgens are well known to influence sebum synthesis and secretion. Various factors related to androgen biosynthesis are expressed in human sebaceous glands. In this study, immunohistochemical analysis of human skin specimens from 43 subjects indicated that various androgen-producing and -metabolizing enzymes were functionally localized to sebocytes accumulating lipid droplets and that the exclusive expression of 17β-hydroxysteroid dehydrogenase type 2 (17β-HSD2 (HSD17B2)) in sebaceous glands was negatively correlated with that of peroxisome proliferator-activated receptor gamma (PPARγ (PPARG)), which also significantly changed in an age-dependent manner. We also demonstrated that the changes of 17β-HSD2 expression in human immortalized sebocytes (SZ95) influenced the expressions of sebogenesis-related factors. In addition, the overexpression of 17β-HSD2 in SZ95 significantly increased the androstenedione production and markedly decreased the amounts of testosterone and dihydrotestosterone when DHEA was added externally. On the other hand, the phosphorylation of mammalian target of rapamycin, which is well known to induce sebum secretion and the onset and/or aggravation of acne, was increased by the addition of testosterone in the presence of IGF1 in hamster sebocytes. These results all indicated that local androgen biosynthesis and metabolism in human sebaceous glands could play a pivotal role in sebum synthesis and secretion.

Expression of 17β-hydroxysteroid dehydrogenase type 1 in gastric cancer

There are several findings suggesting the protective role of estrogens in gastric carcinogenesis. Extragonadal 17β-estradiol (E2) may be formed during estrone (E1) reduction to E2 by 17-β-hydroxysteroid dehydrogenase type 1 (HSD17B1). Therefore, we studied the HSD17B1 transcript and protein levels in primary nontumoral and tumoral gastric tissue from the same 21 patients with gastric cancer (GC). We also assessed the effect of 5-Aza-2′-deoxycytidine (5-dAzaC), on the methylation status of HSD17B1 and its expression and conversion of E1 to E2 in HGC-27 and EPG 85-257 GC cells. We identified the presence of HSD17B1 transcript and protein in HGC-27 and EPG 85-257 GC cells as well as in primary nontumoral and tumoral tissues from patients with GC. Moreover, we found that 5-dAzaC significantly up-regulated the HSD17B1 transcript and protein levels, which is associated with increased conversion of E1 to E2 in HGC-27 and EPG 85-257 GC cells. The changes in HSD17B1 expression in both HGC-27 and EPG 85-257 cells were accompanied by 5-dAzaC induced DNA demethylation in the 5′ flanking region. Our results demonstrated that HSD17B1 expression and its ability to convert the weak estrogen E1 to the more potent E2 can be associated with DNA methylation in the 5′ flanking region in GC cells.

Androgen deprivation promotes intratumoral synthesis of dihydrotestosterone from androgen metabolites in prostate cancer

Intratumoral synthesis of dihydrotestosterone (DHT) from precursors cannot completely explain the castration resistance of prostate cancer. We showed that DHT was intratumorally synthesized from the inactive androgen metabolites 5α-androstane-3α/β,17β-diol (3α/β-diol) in prostate cancer cells via different pathways in a concentration-dependent manner. Additionally, long-term culture in androgen-deprived media increased transcriptomic expression of 17β-hydroxysteroid dehydrogenase type 6 (HSD17B6), a key enzyme of oxidative 3α-HSD that catalyzes the conversion of 3α-diol to DHT in prostate cancer cells. Correspondingly, the score for HSD17B6 in tissues of 42 prostate cancer patients undergoing androgen deprivation therapy (ADT) was about 2-fold higher than that in tissues of 100 untreated individuals. In men receiving ADT, patients showing biochemical progression had a higher HSD17B6 score than those without progression. These results suggested that 3α/β-diol also represent potential precursors of DHT, and the back conversion of DHT from androgen derivatives can be a promising target for combination hormone therapy.

Molecular cloning and expression of 17β-hydroxysteroid dehydrogenase type 2 gene in Hu sheep

17β-Hydroxysteroid dehydrogenase type 2 (17β-HSD2) catalyzes the NADP+-dependent oxidation of the most potent estrogen 17β-estradiol into the weak estrogen estrone, and the conversion of testosterone to androstenedione. It has been reported that 17β-HSD2 was expressed in many tissues in human, rats, however, the full-length sequence of 17β-HSD2 gene and its expression in ewe were still unknown. In this study, we cloned the full-length cDNA sequence and investigated mRNA differential expression in 28 tissues of 12 adult Hu-Sheep which were fed with high- and low- dietary intake. The 1,317bp full-length cDNA sequence was first cloned. The coding region was 1,167bp in length, and the monomer was estimated to contain 389 amino acid residues. It shares high AA sequence identity with that of bos Taurus (96.13%), sus scrofa (77.06%), canis lupus familiaris (70.44%), Callithrix jacchus (65.72%), Nomascus leucogenys (65.46%), pan troglodytes (65.21%), human (64.69%), mus musculus (58.35%), and a comparatively lower identity to danio rerio (37.85%). 17β-HSD2 gene was high expressed in gastrointestinal (GI) tract, liver, but weakly expressed in other tissues. No detected expression was examined in lung. 17β-HSD2 gene expression was significantly difference in rumen, omasum, duodenum, cecum, hypophysis after high- and low- dietary intake. Results from the present study suggested that 17β-HSD2 plays a crucial role in almost all tissues protecting against excessive levels of active steroid hormone, and GI tract maybe an important steroid hormone metabolizing organ in Hu-Sheep. This present study is the first to provide the primary foundation for further insight into this ovine gene.

Decreased expression of 17β-hydroxysteroid dehydrogenase type 1 is associated with DNA hypermethylation in colorectal cancer located in the proximal colon

BackgroundThe importance of 17β-estradiol (E2) in the prevention of large bowel tumorigenesis has been shown in many epidemiological studies. Extragonadal E2 may form by the aromatase pathway from androstenedione or the sulfatase pathway from estrone (E1) sulfate followed by E1 reduction to E2 by 17-β-hydroxysteroid dehydrogenase (HSD17B1), so HSD17B1 gene expression may play an important role in the production of E2 in peripheral tissue, including the colon.MethodsHSD17B1 expression was analyzed in colorectal cancer cell lines (HT29, SW707) and primary colonic adenocarcinoma tissues collected from fifty two patients who underwent radical colon surgical resection. Histopathologically unchanged colonic mucosa located at least 10-20 cm away from the cancerous lesions was obtained from the same patients. Expression level of HSD17B1 using quantitative PCR and western blot were evaluated. DNA methylation level in the 5' flanking region of HSD17B1 CpG rich region was assessed using bisulfite DNA sequencing and HRM analysis. The influence of DNA methylation on HSD17B1 expression was further evaluated by ChIP analysis in HT29 and SW707 cell lines. The conversion of estrone (E1) in to E2 was determined by electrochemiluminescence method.ResultsWe found a significant decrease in HSD17B1 transcript (p = 0.0016) and protein (p = 0.0028) levels in colorectal cancer (CRC) from the proximal but not distal colon and rectum. This reduced HSD17B1 expression was associated with significantly increased DNA methylation (p = 0.003) in the CpG rich region located in the 5' flanking sequence of the HSD17B1 gene in CRC in the proximal but not distal colon and rectum. We also showed that 5-dAzaC induced demethylation of the 5' flanking region of HSD17B1, leading to increased occupation of the promoter by Polymerase II, and increased transcript and protein levels in HT29 and SW707 CRC cells, which contributed to the increase in E2 formation.ConclusionsOur results showed that reduced HSD17B1 expression can be associated with DNA methylation in the 5' flanking region of HSD17B1 in CRC from the proximal colon.

Endometrial Indian hedgehog expression is decreased in women with endometriosis

Nuclear and cytoplasmic endometrial expression of Indian hedgehog increased from the late proliferative to mid and late secretory phases in 26 healthy volunteers compared with 30 women with endometriosis. The abnormal expression of Indian hedgehog protein in women with endometriosis suggests a resistance to P action.

Butyrate Induces Expression of 17β-Hydroxysteroid Dehydrogenase Type 1 in HT29 and SW707 Colorectal Cancer Cells

Epidemiological studies have revealed that butyrate and 17β-estradiol (E2) may decrease the incidence of colorectal cancer (CRC). In peripheral tissue, E2 can be produced locally by 17β-hydroxysteroid dehydrogenase 1 (HSD17B1) estrone (E1) reduction. Using quantitative real-time polymerase chain reaction and western blotting analysis, we found that sodium butyrate significantly upregulates HSD17B1 long and short transcripts and protein levels in HT29 and SW707 CRC cells. Chromatin immunoprecipitation analysis showed that upregulation of these transcript levels correlated with an increase in binding of Polymerase II to proximal and distal promoters of HSD17B1. Moreover, we observed that upregulation of HSD17B1 protein levels was associated with increased conversion of E1 to E2 in HT29 and SW707 CRC cells. Since sodium butyrate increases the conversion of E1 to E2, our findings may support the validity of butyrate in the prophylaxis of CRC incidence.

Abstract 355: Genetic alterations in 17β-hydroxysteroid dehydrogenase type 2 and 7 correlates with mRNA-expression but not estrogen levels in breast cancer

Abstract Background: Estrogens are believed to play an important role in both development and sustained growth of breast cancer. Estradiol (E2), the most biologically active estrogen, is often elevated in breast cancer tissue, and high plasma levels of E2 are correlated to increased breast cancer risk in postmenopausal women. Previously, we have shown that uptake of estrogen due to binding to the estrogen receptor (ER), is a probable determinant of intratumoral E2. Furthermore, we reported that increased expression of 17β-hydroxysteroid dehydrogenase type 7 (HSD17B7) might explain the increased ratio of E2 to estrone (E1) in breast tumors compared to non-tumorous breast tissue. Here we explored whether genetic alterations in HSD17B-isoforms might predict estrogen disposition in breast cancer. Materials and methods: Tumor and normal breast tissue specimens were collected from 50 patients (37 postmenopausal and 13 premenopausal women) undergoing mastectomy. Samples were snap-frozen in the theatre. To evaluate potential mechanisms regulating intra-tumor and plasma estradiol levels, HSD17B2 and HSD17B7 were evaluated for mutation status, promoter hypermethylation and gene copy number. In addition, we quantified the transcription level of two HSD17B7 isoforms (HSD17B7_I and HSD17B7_II). Results: We identified a novel single nucleotide polymorphism (SNP) in the HSD17B7 promoter region (transcription start + 56: T&amp;gt;C) and found it correlated to increased enzyme expression level (p = 0.016). Also, we observed a novel SNP in the HSD17B2 promoter region (transcription start + 35: C&amp;gt;T) associated with a lower expression level (p = 0.019). Nineteen patients were found to harbour HSD17B7-duplications predicting elevated mRNA-expression levels (p = 0.056). While some tumors revealed promoter hypermethylation in both HSD17B2 and 7, hypermethylation status was not associated with low mRNA-levels. None of these genetic alterations correlated to plasma or tissue estrogen levels. Conclusion: Genetic alterations in HSD17B2 and 7 were found to influence the transcription level of these genes, but not estradiol levels in plasma or breast cancer tissue. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 355. doi:10.1158/1538-7445.AM2011-355

Expression of 17β-hydroxysteroid dehydrogenase type 2 and type 5 in breast cancer and adjacent non-malignant tissue: A correlation to clinicopathological parameters

Estrogens play an important role in the development and progression of breast cancer. 17β-Hydroxysteroid dehydrogenase (17β-HSD) type 2 and type 5 are involved in sex steroid metabolism. 17β-HSD type 2 converts estradiol to estrone while 17β-HSD type 5 converts androstenedione to testosterone. Using immunocytochemistry, we have studied the expression of 17β-HSD type 2 and type 5 in 50 specimens of breast carcinoma and adjacent non-malignant tissues. The results were correlated with the estrogen receptor α (ERα) and β (ERβ), progesterone receptor A (PRA) and B (PRB), androgen receptor and CDC47 and with the tumor stage, tumor size, nodal status and menopausal status. 17β-HSD type 2 was expressed in 20% and 17β-HSD type 5 in 56% of breast cancer specimens. In adjacent normal tissues, both enzymes were highly expressed in almost all the patients. No significant association could be found between the expression of 17β-HSD type 2 and 17β-HSD type 5 and between the expression of each enzyme and the clinicopathological parameters studied. The decrease in 17β-HSD type 2 and 17β-HSD type 5 expressions in breast cancer may play a predominant role in the development and/or progression of the cancer by modifying the intratumoral levels of estrogens and androgens.

Dual Subcellular Localization in the Endoplasmic Reticulum and Peroxisomes and a Vital Role in Protecting against Oxidative Stress of Fatty Aldehyde Dehydrogenase Are Achieved by Alternative Splicing

Fatty aldehyde dehydrogenase (FALDH, ALDH3A2) is thought to be involved in the degradation of phytanic acid, a saturated branched chain fatty acid derived from chlorophyll. However, the identity, subcellular distribution, and physiological roles of FALDH are unclear because several variants produced by alternative splicing are present in varying amounts at different subcellular locations. Subcellular fractionation experiments do not provide a clear-cut conclusion because of the incomplete separation of organelles. We established human cell lines heterologously expressing mouse FALDH from each cDNA without tagging under the control of an inducible promoter and detected the variant FALDH proteins using a mouse FALDH-specific antibody. One variant, FALDH-V, was exclusively detected in peroxisomal membranes. Human FALDH-V with an amino-terminal Myc sequence also localized to peroxisomes. The most dominant form, FALDH-N, and other variants examined, however, were distributed in the endoplasmic reticulum. A gas chromatography-mass spectrometry-based analysis of metabolites in FALDH-expressing cells incubated with phytol or phytanic acid showed that FALDH-V, not FALDH-N, is the key aldehyde dehydrogenase in the degradation pathway and that it protects peroxisomes from oxidative stress. In contrast, both FALDHs had a protective effect against oxidative stress induced by a model aldehyde for lipid peroxidation, dodecanal. These results suggest that FALDH variants are produced by alternative splicing and share an important role in protecting against oxidative stress in an organelle-specific manner.

Organotin compounds enhance 17β-hydroxysteroid dehydrogenase type I activity in human choriocarcinoma JAr cells: Potential promotion of 17β-estradiol biosynthesis in human placenta

Organotin compounds, such as tributyltin (TBT) and triphenyltin (TPT), are typical environmental contaminants and suspected endocrine-disrupting chemicals because they cause masculinization in female mollusks. However, it remains unclear whether organotin compounds also cause crucial toxicities in human sexual development and reproductive functions. We investigated the effects of 17 tin compounds on the catalytic activity and mRNA expression of 17β-hydroxysteroid dehydrogenase type I (17β-HSD I) in human choriocarcinoma JAr cells. At nontoxic concentrations, both trialkyltins with propyl, butyl or cyclohexyl substituents on the tin atom and triphenyltin (TPT) enhanced 17β-HSD I mRNA transcription and enzyme activity in a dose-dependent fashion. Although tetraalkyltin compounds such as tetrabutyltin and tributylvinyltin also increased the mRNA expression and enzyme activity of 17β-HSD I, the concentrations necessary for activation were >30–100 times greater than those for trialkyltins. Inorganic tin had no effect on the catalytic activity and mRNA expression of 17β-HSD I. Interestingly, diphenyltin and monophenyltin, which are metabolites of TPT, enhanced 17β-HSD I activity with a concomitant increase in mRNA expression, whereas dibutyltin and monobutyltin, which are metabolites of tributyltin, enhanced 17β-HSD I activity without a concomitant increase in mRNA expression. These results suggest that organotin compounds are potent stimulators of 17β-estradiol biosynthesis to enhance 17β-HSD I activity in the human placenta in vitro; the placenta represents a potential target organ for these compounds, whose endocrine-disrupting effects might be the result of local changes in 17β-estradiol concentrations in pregnant women.

Androgen formation and metabolism in the pulmonary epithelial cell line A549: expression of 17beta-hydroxysteroid dehydrogenase type 5 and 3alpha-hydroxysteroid dehydrogenase type 3.

Surfactant synthesis within developing fetal lung type II cells is affected by testosterone and 5alpha-dihydrotestosterone (5alpha-DHT). The pulmonary epithelial cell line A549, isolated from a human lung carcinoma, like normal lung type II cell, produces disaturated phosphatidylcholines and has been widely used for studying the regulation of surfactant production. Androgen receptor has been detected in A549 cells; however, the capacity of these cells for androgen synthesis and metabolism has not been investigated at molecular level. This study was undertaken to identify the steroidogenic enzymes involved in the formation and metabolism of androgens from adrenal C19 steroid precursors in A549 cells. When cultured in the presence of normal FCS, A549 intact cells converted DHEA to androstenediol, androstenedione principally to testosterone, and 5alpha-DHT to 5alpha-androstane 3alpha,17beta-diol. High levels of 17beta-hydroxysteroid dehydrogenase (HSD) and 3alpha-HSD activities were detected in both cytosol and microsomes isolated from homogenates. Analysis of A549 RNA indicated the presence of 17beta-HSD type 4 and type 5, and of 3alpha-HSD type 3 messenger RNAs. Very low levels of 3beta-HSD type 1 and 5alpha-reductase type 1 messenger RNAs and activities were detected. With regard to active androgen formation, there was little or no capacity for the conversion of DHEA to 5alpha-DHT. In contrast, androstenedione was rapidly transformed to testosterone. The pattern of steroid metabolism was not affected by the use of charcoal-stripped FCS or by the synthetic glucocorticoid dexamethasone. Together, our findings show that A549 cells express a pattern of steroid metabolism in which 17beta-HSD type 5 and 3alpha-HSD type 3 are the predominant enzymes. The level of androgens is regulated at the level of catalysis in intact cells such that the intracellular level of testosterone is stabilized, whereas 5alpha-DHT is rapidly inactivated by reduction to 3alpha,17beta-diol. This pattern of androgen metabolism has implications for the relative importance of testosterone and 5alpha-DHT in normal lung development and surfactant production.

Expression of 17 beta-hydroxysteroid dehydrogenase type 5 in human ovary: a pilot study.

Conversion of androstenedione to testosterone, the most potent androgen secreted by the ovary, is carried out by androgenic 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity. The molecular basis for this is unclear. We tested the hypothesis that type 5 17 beta-HSD (17 beta-HSD5) is responsible for testosterone formation from androstenedione in the human ovary. We used primers specific for each type of 17 beta-HSD to identify quantitatively and directly sequence the polymerase chain reaction products of a human ovary library. 17 beta-HSD1, 17 beta-HSD4, and 17 beta-HSD5 were detected in the library lysate, but not 17 beta-HSD2 or 17 beta-HSD3. 17 beta-HSD5 was the predominant androgenic form of 17 beta-HSD expressed in human ovary. These data suggest that 17 beta-HSD5 may play a major role in testosterone biosynthesis by the human ovary. Further investigation of the regulation of 17 beta-HSD5 gene expression is warranted with regard to ovarian testosterone secretion in normal and abnormal states of ovarian function, such as polycystic ovary syndrome.

Expression of 17β-Hydroxysteroid Dehydrogenase Type 5 in Human Ovary: A Pilot Study

Expression of 17β-Hydroxysteroid Dehydrogenase Type 5 in Human Ovary: A Pilot Study

Expression of 17β-Hydroxysteroid Dehydrogenase Type 1 and Type 2, P450 Aromatase, and 20α-Hydroxysteroid Dehydrogenase Enzymes in Immature, Mature, and Pregnant Rats.

In the present study, we evaluated the expression and regulation of 17beta-hydroxysteroid dehydrogenase (17HSD) type 1 and type 2, cytochrome P450 aromatase (P450arom), and 20alpha-hydroxysteroid dehydrogenase (20HSD) in mature and pregnant rats. Immunohistochemical analysis of rat 17HSD type 1 showed that the enzyme is exclusively expressed in the granulosa cells of developing, healthy, primary, secondary, and tertiary follicles at all stages of the estrous cycle and pregnancy, and is not detected in the corpora lutea. The data showed that the amount of the enzyme expressed in the follicle increases as follicular maturation progresses and is highest in tertiary and Graafian follicles. However, Northern blot analysis of total RNA from whole ovaries showed a rather constitutive expression of the 17HSD type 1 enzyme. It is evident that compared with P450arom, 17HSD type 1 is more widely expressed in the follicles during the various maturational stages of folliculogenesis. Hence, the data indicate distinct localization, expression, and regulation patterns for 17HSD type 1 and P450arom during the rat estrous cycle and pregnancy. Furthermore, compared with the two estradiol biosynthetic enzymes, a different expression pattern was detected for 20HSD messenger RNA. During the estrous cycle the enzyme was detected in the ovaries throughout the cycle, and in the ovaries of pregnant animals the enzyme showed an expression pattern the opposite of that observed for P450arom. Rat 17HSD type 2, not detected in the ovaries, was constitutively expressed in both female and male liver and small intestine in 21-day-old fetuses up to 6-week-old mature animals. Similarly, in these tissues the enzyme was constitutively expressed in normal cycling and pregnant animals, but it showed increasing expression in the placenta as pregnancy advanced. The relatively constitutive expression of the enzyme at all physiological stages of the animals suggests a general role for the enzyme in the inactivation of circulating sex steroids.

Expression of 17β-Hydroxysteroid Dehydrogenase Type IV in Chick Retinal Pigment Epithelium

Retinal pigment epithelium (RPE) has essential roles that maintain functions of the neural retina. Previously, we described that the 3b5 monoclonal antibody (3b5 mAb) recognized the RPE cells in the chick embryonic eye. In the present study, a gene coding for the 3b5 antigen has been cloned and sequenced. A 10-day-old embryonic RPE cDNA library was constructed in lambda Uni-ZAP XR, and screened with the 3b5 mAb as a probe. The complete nucleotide sequence of the antigen recognized by the 3b5 mAb was obtained. The cDNA encodes a 735 amino acid protein with a calculated molecular mass of 80147 Da. The deduced amino acid sequence shares 72% identity with the human 17β-hydroxysteroid dehydrogenase (17β-HSD) type IV. Northern blot analysis detected a 2.9 kb transcript. Immunohistochemical and in-situ hybridization studies revealed that 17β-HSD type IV was preferentially expressed in the RPE cells. The expression of steroid metabolizing enzymes in the RPE cells is able to create estrogenic environment, which may have a role of maintenance of the neural retina.