Sex steroid-dependent and -independent action of hydroxysteroid (17beta) Dehydrogenase 2: evidence from transgenic female mice

Transcriptome of 17β-hydroxysteroid dehydrogenase type 2 plays both hormone-dependent and hormone-independent roles in MCF-7 breast cancer cells

Breast cancer is a major cause of cancer-related death for women in western countries. 17β-Hydroxysteroid dehydrogenases (17β-HSDs) play important roles in the last step of sex-hormone activation and the first step of sex-hormone inactivation. 17β-HSD2 is responsible for oxidizing the sex hormones. We used microarray technology to analyze the effect of 17β-HSD2 on the MCF-7 cell transcript profile after knocking down 17β-HSD2. Five hundred forty-two genes were regulated 1.5-fold or higher after treatment with 17β-HSD2 siRNA. Knocking down 17β-HSD2 interrupted nucleosome assembly. Pathway-Act-Network analysis showed that the MAPK and apoptosis signaling pathways were most regulated. In the gene-gene interaction network analysis, UGT2B15, which is involved in hormone metabolism, was the most regulated core gene. FOS, GREB1, and CXCL12 were the most regulated genes, and CXCL12 was related to tumor migration. Following 17β-HSD2 knock-down, the cell viability decreased to 75.9%. The S-phase percentage decreased by 19.4%, the Q2-phase percentage in cell apoptosis testing increased by 1.5 times, and cell migration decreased to 66.0%. These results were consistent with our gene chip analysis and indicated that 17β-HSD2 plays both hormone-dependent and hormone-independent enzymatic roles. In-depth investigations of this enzyme on the genomic level will help clarify its related molecular mechanisms.

Local estrogen metabolism (intracrinology) in endometrial cancer: A systematic review

Endometrial cancer (EC) is the most common malignancy of the female gynaecological tract and increased exposure to estrogens is a risk factor. EC cells are able to produce estrogens locally using precursors like, among others, adrenal steroids present in the serum. This is referred to as local estrogen metabolism (or intracrinology) and consists of a complex network of multiple enzymes. Particular relevant to the final generation of active estrogens in endometrial cells are: steroid sulfatase (STS), estrogen sulfotransferase (SULT1E1), aromatase (CYP19A1), 17β-hydroxysteroid dehydrogenase (HSD17B) type 1 and type 2. During the last decades, a plethora of studies explored the level of these enzymes in EC but contrasting data were reported, which generated vigorous debate and controversies. Several reviews attempted at clarifying some of the debated issues, but published reviews are based on investigator-defined bibliography selection and not on systematic analysis. Therefore, we performed a systematic review of the literature reporting about the level of STS, SULT1E1, CYP19A1, HSD17B1 and HSD17B2 in EC. Additional intracrine enzymes and networks (e.g., HSD17Bs other than types 1 and 2, aldo-keto reductases, progesterone and androgen metabolism) were non-systematically reviewed as well.

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.

Estrogen Deficiency and the Origin of Obesity during Menopause

Sex hormones strongly influence body fat distribution and adipocyte differentiation. Estrogens and testosterone differentially affect adipocyte physiology, but the importance of estrogens in the development of metabolic diseases during menopause is disputed. Estrogens and estrogen receptors regulate various aspects of glucose and lipid metabolism. Disturbances of this metabolic signal lead to the development of metabolic syndrome and a higher cardiovascular risk in women. The absence of estrogens is a clue factor in the onset of cardiovascular disease during the menopausal period, which is characterized by lipid profile variations and predominant abdominal fat accumulation. However, influence of the absence of these hormones and its relationship to higher obesity in women during menopause are not clear. This systematic review discusses of the role of estrogens and estrogen receptors in adipocyte differentiation, and its control by the central nervous systemn and the possible role of estrogen-like compounds and endocrine disruptors chemicals are discussed. Finally, the interaction between the decrease in estrogen secretion and the prevalence of obesity in menopausal women is examined. We will consider if the absence of estrogens have a significant effect of obesity in menopausal women.

The diversity of sex steroid action: novel functions of hydroxysteroid (17β) dehydrogenases as revealed by genetically modified mouse models

Disturbed action of sex steroid hormones, i.e. androgens and estrogens, is involved in the pathogenesis of various severe diseases in humans. Interestingly, recent studies have provided data further supporting the hypothesis that the circulating hormone concentrations do not explain all physiological and pathological processes observed in hormone-dependent tissues, while the intratissue sex steroid concentrations are determined by the expression of steroid metabolising enzymes in the neighbouring cells (paracrine action) and/or by target cells themselves (intracrine action). This local sex steroid production is also a valuable treatment option for developing novel therapies against hormonal diseases. Hydroxysteroid (17β) dehydrogenases (HSD17Bs) compose a family of 14 enzymes that catalyse the conversion between the low-active 17-keto steroids and the highly active 17β-hydroxy steroids. The enzymes frequently expressed in sex steroid target tissues are, thus, potential drug targets in order to lower the local sex steroid concentrations. The present review summarises the recent data obtained for the role of HSD17B1, HSD17B2, HSD17B7 and HSD17B12 enzymes in various metabolic pathways and their physiological and pathophysiological roles as revealed by the recently generated genetically modified mouse models. Our data, together with that provided by others, show that, in addition to having a role in sex steroid metabolism, several of these HSD17B enzymes possess key roles in other metabolic processes: for example, HD17B7 is essential for cholesterol biosynthesis and HSD17B12 is involved in elongation of fatty acids. Additional studies in vitro and in vivo are to be carried out in order to fully define the metabolic role of the HSD17B enzymes and to evaluate their value as drug targets.

Polymorphisms in genes hydroxysteroid-dehydrogenase-17b type 2 and type 4 and endometrial cancer risk

OBJECTIVE

Hydroxysteroid-dehydrogenase-17b (HSD17b) genes control the last step in estrogen biosynthesis. The isoenzymes HSD17b2 and HSD17b4 in the uterus preferentially catalyze the conversion of estradiol, the most potent and active form of estrogen, to estrone, the inactive form of estrogen. Endometrial adenocarcinoma is linked to excessive exposure to estrogens. We hypothesized that single nucleotide polymorphisms (SNPs) in genes HSD17b2 and HSD17b4 may alter the enzyme activity, estradiol levels and risk of disease.

METHODS

Pairwise tag SNPs were selected from the HapMap Caucasian database to capture all known common (minor allele frequency >0.05) genetic variation with a correlation of at least 0.80. Forty-eight SNPs were genotyped in the case-control studies nested within the Nurses' Health Study (NHS) (cases=544, controls=1296) and the Women's Health Study (WHS) (cases=130, controls=389). The associations with endometrial cancer were examined using conditional logistic regression to estimate odds ratio and 95% confidence intervals adjusted for known risk factors. Results from the two studies were using fixed effects models. We additionally investigated whether SNPs are predictive of plasma estradiol and estrone levels in the NHS using linear regression.

RESULTS

Four intronic SNPs were significantly associated with endometrial cancer risk (p-value<0.05). After adjustment for multiple testing, we did not observe any significant associations between SNPs and endometrial cancer risk or plasma hormone levels.

CONCLUSIONS

This is the first study to comprehensively evaluate variation in HSD17b2 and HSD17b4 in relation to endometrial cancer risk. Our findings suggest that variation in HSD17b2 and HSD17b4 does not substantially influence the risk of endometrial cancer in Caucasians.

A validated and rapid high-performance liquid chromatography method for the quantification of conversion of radio-labelled sex steroids

The 17β-hydroxysteroid dehydrogenase enzymes modify the availability of potent sex steroids and have thus attracted interest in the study of several steroid-dependent pathologies including breast, endometrial and prostate cancers. An increased awareness of the importance of steroidogenic enzymes has brought forth a demand for efficient assays to study the effects of individual enzymes on steroid levels. Methods used for assessing steroid conversion are often laborious and frequently involve hazardous sample preparation steps. We developed and validated an optimised simple method for sample preparation of sex steroids using protein precipitation by the addition of zinc sulphate/sodium hydroxide. The interconversion of radio-labelled oestrogens and androgens was quantified using high-performance liquid chromatography separation of oestrone, oestradiol, androstenedione and testosterone followed by online radiometric flow scintillation analysis. The method, which can be applied for assessing, e.g., the efficacy of inhibitors of steroidogenic enzymes, was successfully used for evaluating oestrogenic interconversion in breast cancer cell lines MCF7 and T-47D.