Multiple signal transduction pathways mediate interleukin-4-induced 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase in normal and tumoral target tissues

A cross-sectional survey of adrenal steroid hormones among overweight/obese boys according to puberty stage

BACKGROUND

Obesity is associated with many chronic diseases including cortisol rhythm disorder and low testosterone. Furthermore, studies on obese children are quite limited and no concordance results have been obtained, especially for boys in puberty. Moreover, the sample sizes of previous studies were small, and were not representative.

METHODS

We conducted a cross-sectional survey including 1148 boys aged 6-14 years, they were divided into overweight/obesity (OW/OB) group and normal weight (NW) group. Puberty status was assessed according to Tanner scale and testicular volume. Serum levels of pregnenolone, 17-OH progesterone, corticosterone, dehydroepiandrosterone (DHEA), and androstenedione were detected by LC-MS. Serum free testosterone and sex hormone-binding globulin (SHBG) levels were measured by chemiluminescence immunoassay.

RESULTS

The 17-OH progesterone, DHEA, androstenedione and free testosterone levels of OW/OB boys at prepubertal stage or at the age 6 = < 10 years group were higher than those of the NW boys (all the P values were < 0.01). Furthermore, androstenedione and free testosterone levels were lower in OW/OB boys at late puberty, and the trend continued at the post pubertal stage for FT (P < 0.01-0.05). DHEA, androstenedione, and FT levels persisted to be higher at the 10~ < 12 years in OW/OB boys but not for 17-OH progesterone. FT level was lower in the OW/OB group at the 12~ < 15 years group. The SHBG levels in the OW/OB boys were lower than those in the NW ones at the 6~12 years group, and prepubertal to early pubertal stage.

CONCLUSIONS

Premature adrenarche is more likely in OW/OB boys. More attention should be given to the lower androgen levels of OW/OB boys at late pubertal and post pubertal stages.

Genetic Variants Associated with Hyperandrogenemia in PCOS Pathophysiology

Polycystic ovary syndrome is a multifactorial endocrine disorder whose pathophysiology baffles many researchers till today. This syndrome is typically characterized by anovulatory cycles and infertility, altered gonadotropin levels, obesity, and bulky multifollicular ovaries on ultrasound. Hyperandrogenism and insulin resistance are hallmark features of its complex pathophysiology. Hyperandrogenemia is a salient feature of PCOS and a major contributor to cosmetic anomalies including hirsutism, acne, and male pattern alopecia in affected women. Increased androgen levels may be intrinsic or aggravated by preexisting insulin resistance in women with PCOS. Studies have reported augmented ovarian steroidogenesis patterns attributed mainly to theca cell hypertrophy and altered expression of key enzymes in the steroidogenic pathway. Candidate gene studies have been performed in order to delineate the association of polymorphisms in genes, which encode enzymes in the intricate cascade of steroidogenesis or modulate the levels and action of circulating androgens, with risk of PCOS development and its related traits. However, inconsistent findings have impacted the emergence of a unanimously accepted genetic marker for PCOS susceptibility. In the current review, we have summarized the influence of polymorphisms in important androgen related genes in governing genetic predisposition to PCOS and its related metabolic and reproductive traits.

The association between skeletal maturation and adrenal androgen levels in obese children and adolescents

PURPOSE

This study aimed to investigate the association between skeletal maturation and adrenal androgen levels in obese children and adolescents.

METHODS

Fifty-three children and adolescents (aged 7-15 years) diagnosed as obese or overweight were investigated. Anthropometric measurements, bone age (BA) determination, serum biochemical analyses, and hormonal measurements were performed. The difference between BA and chronological age (BA-CA, dBACA) was calculated and used to represent the degree of advanced skeletal maturation.

RESULTS

Thirty-one subjects were classified into the obese group and 22 subjects into the overweight group. Insulin resistance as calculated by the homeostasis model assessment of insulin resistance (HOMA-IR) was significantly higher in the obese group than in the overweight group (4.03±2.20 vs. 2.86±1.11, P=0.026). The skeletal maturation of the obese group was advanced, but the dBACA did not differ between the obese and overweight groups statistically (1.43±1.35 vs. 0.91±1.15, P=0.141). Serum dehydroepiandrosterone sulfate (DHEA-S) levels were significantly higher in subjects with dBACA>1 compared to those with dBACA≤1 (104.3±62.2 vs. 59.6±61.0, P=0.014). Correlation analyses demonstrated that dBACA was positively correlated with body mass index standard deviation scores (r=0.35, P=0.010), fasting insulin (r=0.36, P=0.009), HOMA-IR (r=0.30, P=0.031), and insulin-like growth factor-binding protein-3 (r=0.331, P=0.028). In multivariate linear regression analysis, HOMA-IR (P=0.026) and serum DHEA-S (P=0.032) were positively correlated with the degree of advanced skeletal maturation.

CONCLUSION

Advanced skeletal maturation is associated with increased insulin resistance and elevated DHEA-S levels in obese children and adolescents.

Longitudinal analyses of the steroid metabolome in obese PCOS girls with weight loss

OBJECTIVE

The underlying mechanisms of polycystic ovarian syndrome (PCOS) are not fully understood yet. The aim of the study was to get functional insights into the regulation of steroid hormones in PCOS by steroid metabolomics.

DESIGN

This is a longitudinal study of changes of steroid hormones in 40 obese girls aged 13-16 years (50% with PCOS) participating in a 1-year lifestyle intervention. Girls with and without PCOS were matched to age, BMI and change of weight status.

METHODS

We measured progesterone, 17-hydroxyprogesterone, 17-hydroxyprogenolon, 11-deoxycorticosterone, 21-deoxycorticosterone, deoxycorticosterone, corticosterone, 11-deoxycortisol, cortisol, cortisone, androstenedione, testosterone, dehydroepiandrostendione-sulfate (DHEA-S), estrone and estradiol by LC-MS/MS steroid profiling at baseline and one year later.

RESULTS

At baseline, obese PCOS girls demonstrated significantly higher androstenedione and testosterone concentrations compared to obese girls without PCOS, whereas the other steroid hormones including glucocorticoids, mineralocorticoids, estrogens and precursors of androgens did not differ significantly. Weight loss in obese PCOS girls was associated with a significant decrease of testosterone, androstenedione, DHEA-S, cortisol and corticosterone concentrations. Weight loss in obese non-PCOS girls was associated with a significant decrease of DHEA-S, cortisol and corticosterone concentrations, whereas no significant changes of testosterone and androstenedione concentrations could be observed. Without weight loss, no significant changes of steroid hormones were measured except an increase of estradiol in obese PCOS girls without weight loss.

CONCLUSIONS

The key steroid hormones in obese adolescents with PCOS are androstenedione and testosterone, whereas glucocorticoids, mineralocorticoids, estrogens and precursors of androgens did not differ between obese girls with and without PCOS.

Effects of 4-nonylphenol on the steroidogenesis of human adrenocarcinoma cell line (NCI-H295R)

In this study, the human H295R adrenocarcinoma cell line was exposed to different concentrations (0.04, 0.2, 1.0, 2.5 or 5 µg/mL) of nonylphenol (NP) to investigate its impact on the inhibition or induction of the steroid hormones production during 48 h of in vitro culture. The hormone production was measured using ELISA kits. Results of this in vitro study suggest various effect of nonylphenol in relatively low concentrations on the selected steroid hormones production by the human H295R adrenocarcinoma cell line. The inhibiting impact on progesterone and androstenedione production was observed. The amount of progesterone was significantly decreased at 1.0, 2.5 and 5 µg/mL NP. Equally, the androstenedione production significantly decreased at 5 µg/mL NP. On the other hand, the amount of testosterone and 17β-estradiol was induced after nonylphenol exposition. The significant increase of testosterone level was found out at treatment with 5 µg/mL NP. 17β-estradiol production significantly increased at the doses of 2.5 and 5 µg/mL NP.

Dynamic modularity of host protein interaction networks in Salmonella Typhi infection

Background

Salmonella Typhi is a human-restricted pathogen, which causes typhoid fever and remains a global health problem in the developing countries. Although previously reported host expression datasets had identified putative biomarkers and therapeutic targets of typhoid fever, the underlying molecular mechanism of pathogenesis remains incompletely understood.

Methods

We used five gene expression datasets of human peripheral blood from patients suffering from S. Typhi or other bacteremic infections or non-infectious disease like leukemia. The expression datasets were merged into human protein interaction network (PIN) and the expression correlation between the hubs and their interacting proteins was measured by calculating Pearson Correlation Coefficient (PCC) values. The differences in the average PCC for each hub between the disease states and their respective controls were calculated for studied datasets. The individual hubs and their interactors with expression, PCC and average PCC values were treated as dynamic subnetworks. The hubs that showed unique trends of alterations specific to S. Typhi infection were identified.

Results

We identified S. Typhi infection-specific dynamic subnetworks of the host, which involve 81 hubs and 1343 interactions. The major enriched GO biological process terms in the identified subnetworks were regulation of apoptosis and biological adhesions, while the enriched pathways include cytokine signalling in the immune system and downstream TCR signalling. The dynamic nature of the hubs CCR1, IRS2 and PRKCA with their interactors was studied in detail. The difference in the dynamics of the subnetworks specific to S. Typhi infection suggests a potential molecular model of typhoid fever.

Conclusions

Hubs and their interactors of the S. Typhi infection-specific dynamic subnetworks carrying distinct PCC values compared with the non-typhoid and other disease conditions reveal new insight into the pathogenesis of S. Typhi.

Steroid hormone profiles in prepubertal obese children before and after weight loss

CONTEXT

Little information is available on the steroid hormone profiles in obese children and their changes after weight loss.

OBJECTIVE

We compared liquid chromatography-tandem mass spectrometry of serum steroid hormone profiles between obese and normal-weight children and studied the differential effects of weight loss on these hormones.

DESIGN

This study was a cross-sectional comparison between obese and normal-weight children and a longitudinal 1-year follow-up study during lifestyle intervention in obese children.

SETTING

The setting of the study was primary care.

PATIENTS

Forty obese prepubertal (mean age 8.5 ± 2.1 years, 48% female, mean body mass index 24.8 ± 3.5 kg/m(2)) and 40 normal-weight children matched for gender, age, and pubertal stage.

INTERVENTION

The study consisted of an outpatient 1-year intervention program based on exercise, behavior, and nutrition therapy.

MAIN OUTCOMES MEASURES

Progesterone, 17-hydroxyprogesterone, 11-deoxycorticosterone, corticosterone, aldosterone, 11-deoxycortisol, cortisol, cortisone, dehydroepiandrosterone sulfate (DHEAS), androstenedione, T, dihydrotestosterone, insulin resistance index of the homeostasis model assessment, and blood pressure were measured.

RESULTS

Prepubertal obese children showed significantly increased androgens (DHEAS, androstenedione, T), mineralocorticoid precursor corticosterone, and glucocorticoids (11-deoxycortisol, cortisol, cortisone) compared with normal-weight children. In contrast to 20 obese children without weight loss, the 20 obese children with substantial weight loss demonstrated a significant decrease of cortisol, cortisone, and corticosterone. Androstenedione and T decreased but DHEAS remained elevated. Changes of the homeostasis model assessment correlated significantly positively with changes of cortisol (r = 0.38) and cortisone (r = 0.43) in partial regression analyses adjusted to changes of weight status.

CONCLUSIONS

In obese prepubertal children, the increased androgens, mineralocorticoid precursors, and glucocorticoids were responsive to weight loss in contrast to DHEAS, suggesting that DHEAS does not seem to be regulated by changes in body mass index.

Global analysis of the eukaryotic pathways and networks regulated by Salmonella typhimurium in mouse intestinal infection in vivo

BACKGROUND

Acute enteritis caused by Salmonella is a public health concern. Salmonella infection is also known to increase the risk of inflammatory bowel diseases and cancer. Therefore, it is important to understand how Salmonella works in targeting eukaryotic pathways in intestinal infection. However, the global physiological function of Salmonella typhimurium in intestinal mucosa in vivo is unclear. In this study, a whole genome approach combined with bioinformatics assays was used to investigate the in vivo genetic responses of the mouse colon to Salmonella. We focused on the intestinal responses in the early stage (8 hours) and late stage (4 days) after Salmonella infection.

RESULTS

Of the 28,000 genes represented on the array, our analysis of mRNA expression in mouse colon mucosa showed that a total of 856 genes were expressed differentially at 8 hours post-infection. At 4 days post-infection, a total of 7558 genes were expressed differentially. 23 differentially expressed genes from the microarray data was further examined by real-time PCR. Ingenuity Pathways Analysis identified that the most significant pathway associated with the differentially expressed genes in 8 hours post-infection is oxidative phosphorylation, which targets the mitochondria. At the late stage of infection, a series of pathways associated with immune and inflammatory response, proliferation, and apoptosis were identified, whereas the oxidative phosphorylation was shut off. Histology analysis confirmed the biological role of Salmonella, which induced a physiological state of inflammation and proliferation in the colon mucosa through the regulation of multiple signaling pathways. Most of the metabolism-related pathways were targeted by down-regulated genes, and a general repression process of metabolic pathways was observed. Network analysis supported IFN-γ and TNF-α function as mediators of the immune/inflammatory response for host defense against pathogen.

CONCLUSION

Our study provides novel genome-wide transcriptional profiling data on the mouse colon mucosa's response to the Salmonella typhimurium infection. Building the pathways and networks of interactions between these genes help us to understand the complex interplay in the mice colon during Salmonella infection, and further provide new insights into the molecular cascade, which is mobilized to combat Salmonella-associated colon infection in vivo.

IL-4-mediated transcriptional regulation of human CYP2E1 by two independent signaling pathways

Cytochrome P450 2E1 (CYP2E1), the alcohol-inducible member of the cytochrome P450 super family, plays an important role in both physiological and pathophysiological processes. The present study focused on the induction of human CYP2E1 transcription by the anti-inflammatory cytokine interleukin-4 (IL-4) in human hepatoma B16A2 cells and revealed that this regulation is mediated by two independent pathways. RNA interference and overexpression of STAT6, indicated that the JAK-STAT signaling pathway is involved in IL-4-dependent induction and mutagenesis revealed the presence of a STAT6 binding site in CYP2E1 proximal promoter region (-583/-574-bp). However, inhibition of the JAK-STAT6 pathway using JAK1 siRNA constructs could only partially inhibit the induction of CYP2E1 promoter constructs indicating the presence of a second IL-4 responsive element. Indeed by using a series of truncated CYP2E1 promoter constructs a second more distal IL-4 responsive element (-1604/-1428-bp) was identified, which was further shown to involve the activation of IRS1/2. This induction was dependent on the transcription factor NFATc1 as IL-4-induced CYP2E1 expression was altered by silencing or overexpressing NFATc1. A NFATc1 binding site was identified in the second distal IL-4 responsive element (-1551/-1545-bp) by chromatin immunoprecipitation (ChIP) analysis. Finally simultaneous siRNA-mediated down-regulation of both STAT6 and NFATc1 or mutation of both STAT6 and NFATc1 binding sites abolished the IL-4-dependent transcriptional induction of CYP2E1, demonstrating that both pathways are required for maximal activation. In conclusion, the present study indicates that the induction of CYP2E1 transcription by IL-4 is mediated through two independent parallel pathways, involving JAK-STAT6 and IRS1/2 and NFATc1.

Breast and prostate cancer: more similar than different

Breast cancer and prostate cancer are the two most common invasive cancers in women and men, respectively. Although these cancers arise in organs that are different in terms of anatomy and physiological function both organs require gonadal steroids for their development, and tumours that arise from them are typically hormone-dependent and have remarkable underlying biological similarities. Many of the recent advances in understanding the pathophysiology of breast and prostate cancers have paved the way for new treatment strategies. In this Opinion article we discuss some key issues common to breast and prostate cancer and how new insights into these cancers could improve patient outcomes.

Tibolone: the way to beat many a postmenopausal ailments

OBJECTIVE

The effects of tibolone on climacteric symptoms, osteoporosis, cardiovascular disease, breasts and the endometrium are summarised, and its role in clinical practice is reviewed in this article.

BACKGROUND

Tibolone has tissue-specific effects on receptors and enzymes that influence the synthesis and metabolism of endogenous sexual steroid hormones.

METHODS

This evaluation was based on the findings from several randomised studies, which addressed the basic and clinical research on tibolone.

RESULTS/CONCLUSION

Clinical trials prove that tibolone is effective in the treatment of the menopausal symptoms and for the postponement and calming of symptoms accompanying age-related diseases. The findings of basic researchers that tibolone affects the metabolism of every cell, including malignant cells, opened a door to a whole new domain of research that has a promising future.

The G2964A 3'-untranslated region polymorphism of the signal transducer and activator of transcription 6 gene is associated with endometriosis in South Indian women

BACKGROUND

The aim of the study was to test whether the signal transducer and activator of transcription 6 (STAT6) gene influences the risk of developing endometriosis.

METHODS

The single-nucleotide polymorphism, G2964A, in the 3'-untranslated region (UTR) of the STAT6 gene was tested for association in a case-control study of 232 affected women and 210 women with no evidence of disease. All the women were infertile, ascertained from the same infertility clinic and of South Indian origin. The genotype frequencies of this polymorphism were compared using PCR and sequencing analysis.

RESULTS

There were statistically significant differences in the genotype distributions (P = 0.002) and allele frequencies (P = 0.0002) between the cases and controls, according to codominant, dominant and recessive genotype models.

CONCLUSIONS

We report for the first time an association between the STAT6 G2964A 3'-UTR polymorphism and endometriosis in South Indian women. This finding suggests that STAT6 may contribute to disease susceptibility in endometriosis, which carries an extra interest as the gene lies in a region which has been implicated, albeit weakly, in a previous genomewide scan.

The Steroid Hormone Biosynthesis Pathway as a Target for Endocrine-Disrupting Chemicals

Various chemicals found in the human and wildlife environments have the potential to disrupt endocrine functions in exposed organisms. Increasingly, the enzymes involved in the steroid biosynthesis pathway are being recognized as important targets for the actions of various endocrine-disrupting chemicals. Interferences with steroid biosynthesis may result in impaired reproduction, alterations in (sexual) differentiation, growth, and development and the development of certain cancers. Steroid hormone synthesis is controlled by the activity of several highly substrate-selective cytochrome P450 enzymes and a number of steroid dehydrogenases and reductases. Particularly aromatase (CYP19), the enzyme that converts androgens to estrogens, has been the subject of studies into the mechanisms by which chemicals interfere with sex steroid hormone homeostasis and function, often related to (de)feminization and (de)masculinazation processes. Studies in vivo and in vitro have focussed on ovarian and testicular function, with less attention given to other steroidogenic organs, such as the adrenal cortex. This review aims to provide a comprehensive overview of the state of knowledge regarding the mechanisms by which chemicals interfere with the function of steroidogenic enzymes in various tissues and organisms. The endocrine toxicities and mechanisms of action related to steroidogenesis of a number of classes of drugs and environmental contaminants are discussed. In addition, several potential in vitro bioassays are reviewed for their usefulness as screening tools for the detection of chemicals that can interfere with steroidogenesis. Analysis of the currently scattered state of knowledge indicates that still relatively little is known about the underlying mechanisms of interference of chemicals with steroidogenesis and their potential toxicity in steroidogenic tissues, neither in humans nor in wildlife. Considerably more detailed and systematic research in this area of (endocrine) toxicology is required for a better understanding of risks to humans and wildlife.

Molecular biology of the 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase gene family

The 3beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4) isomerase (3beta-HSD) isoenzymes are responsible for the oxidation and isomerization of Delta(5)-3beta-hydroxysteroid precursors into Delta(4)-ketosteroids, thus catalyzing an essential step in the formation of all classes of active steroid hormones. In humans, expression of the type I isoenzyme accounts for the 3beta-HSD activity found in placenta and peripheral tissues, whereas the type II 3beta-HSD isoenzyme is predominantly expressed in the adrenal gland, ovary, and testis, and its deficiency is responsible for a rare form of congenital adrenal hyperplasia. Phylogeny analyses of the 3beta-HSD gene family strongly suggest that the need for different 3beta-HSD genes occurred very late in mammals, with subsequent evolution in a similar manner in other lineages. Therefore, to a large extent, the 3beta-HSD gene family should have evolved to facilitate differential patterns of tissue- and cell-specific expression and regulation involving multiple signal transduction pathways, which are activated by several growth factors, steroids, and cytokines. Recent studies indicate that HSD3B2 gene regulation involves the orphan nuclear receptors steroidogenic factor-1 and dosage-sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome gene 1 (DAX-1). Other findings suggest a potential regulatory role for STAT5 and STAT6 in transcriptional activation of HSD3B2 promoter. It was shown that epidermal growth factor (EGF) requires intact STAT5; on the other hand IL-4 induces HSD3B1 gene expression, along with IL-13, through STAT 6 activation. However, evidence suggests that multiple signal transduction pathways are involved in IL-4 mediated HSD3B1 gene expression. Indeed, a better understanding of the transcriptional factors responsible for the fine control of 3beta-HSD gene expression may provide insight into mechanisms involved in the functional cooperation between STATs and nuclear receptors as well as their potential interaction with other signaling transduction pathways such as GATA proteins. Finally, the elucidation of the molecular basis of 3beta-HSD deficiency has highlighted the fact that mutations in the HSD3B2 gene can result in a wide spectrum of molecular repercussions, which are associated with the different phenotypic manifestations of classical 3beta-HSD deficiency and also provide valuable information concerning the structure-function relationships of the 3beta-HSD superfamily. Furthermore, several recent studies using type I and type II purified enzymes have elegantly further characterized structure-function relationships responsible for kinetic differences and coenzyme specificity.

Determination of interleukin-4-responsive region in the human cytochrome P450 2E1 gene promoter

Cytochrome P450 2E1 (CYP2E1) gene expression is known to be induced by interleukin-4 (IL4) and repressed by inflammatory cytokines, such as interleukin-1beta3 (IL1beta3) in human hepatocytes. The mechanisms involved in these transcriptional regulations remain elusive. In order to study these mechanisms, various constructs of the human CYP2E1 promoter were prepared and transfected into the human HepG2 hepatoma cell line. Our findings revealed that an IL4-responsive region of 128bp (-671/-544) was required to mediate induction by IL4. IL1beta caused moderate but significant decrease of the promoter activity, which was abolished when the two cytokines were combined. The IL1beta inhibitory effect is mediated through a regulatory sequence independent of that of IL4. Furthermore, by using specific signaling pathway inhibitors, we demonstrated that IL4 activation required protein kinase C (PKC) activation. In addition, our results suggest that induction by IL4 was not dependent on a single binding site but rather on a complex region which includes putative binding sites for signal transducer and activator of transcription (STAT)6, activator protein (AP)-1, nuclear factor kappa-B (NFkappaB), nuclear factor of activated T cells (NFAT) and CCAAT enhancer binding protein (C/EBP). Electrophoretic mobility shift assays suggest that AP1 and NFAT transcription factors are able to bind to three sites in the IL4-responsive region.

Differential expression of interleukins IL-13 and IL-15 in normal ovarian tissue and ovarian carcinomas

OBJECTIVE

To determine the temporal and spatial expression of interleukins (IL)-13 and IL-15 in ovarian carcinoma compared to normal ovarian tissue.

METHODS

Quantitative RT-PCR, ELISA and immunohistochemistry.

RESULTS

Q-RT-PCR, ELISA and immunohistochemical analysis indicates that IL-13 and IL-15 mRNA and protein are expressed in normal ovary at various phases of the menstrual cycle with immunoreactive proteins detected in granulosa/theca and luteal cells and to a lesser extent in stromal cells and surface epithelial cells. Compared to normal ovary, ovarian carcinoma expresses elevated levels of IL-13 and IL-15 mRNA, with higher IL-13 expression in primary vs. metastatic tumors. IL-13 and IL-15 protein expression was also higher in the tumor tissues compared to ascites. In normal ovary, ovarian tumors and ascites, the ratio of IL-13/IL-15 favored IL-13. Immunoreactive IL-13 and IL-15 proteins were localized primarily in the tumor cells and infiltrated inflammatory cells with increased intensity with disease stage.

CONCLUSION

Normal ovary and ovarian tumors express IL-13 and IL-15 and pattern of their expression in carcinomas suggests that these cytokines may function in various ovarian cellular activities including inflammatory/immune responses that are integrated cellular events taking place in normal ovary and ovarian tumors.