Metformin and exenatide upregulate hepatocyte nuclear factor-4α, sex hormone binding globulin levels and improve hepatic triglyceride deposition in polycystic ovary syndrome with insulin resistance rats.

OBJECTIVE: To explore the efficacy and underlying mechanisms of metformin and exenatide in reversing reproductive and metabolic disturbances in letrozole combined with high-fat diet-induced polycystic ovary syndrome (PCOS) rats. METHODS: Rats with PCOS and insulin resistance (IR) were induced by intra-gastric instillation of letrozole combined with a high-fat diet and verified by histological screening of vaginal exfoliated cells. After metformin and exenatide supplementation, body weight, chow intake and ovarian morphology were observed. Serum biochemical profiles were analyzed using ELISA, while the levels of key anabolism-related proteins, including sex hormone binding globulin (SHBG), hepatocyte nuclear factor-4α (HNF-4α), PI3K, and AKT, were determined using western blotting. RESULTS: The estrus cycle and ovarian morphology of rats with PCOS and IR were significantly recovered following metformin and exenatide treatment, with decreased body weight and chow intake. Furthermore, PCOS-induced changes in metabolic disorders including IR and hepatic triglyceride (TG) deposition, and hyperandrogenemia were reversed by treatment with both drugs. Specifically, the levels of HNF-4α and SHBG in liver tissue of rats with PCOS and IR were upregulated significantly. CONCLUSIONS: Both metformin and exenatide could recover the estrous cycle and ovarian morphology, reduce body weight and high-fat chow intake, and improve glycolipid metabolism disorders and hyperandrogenemia in PCOS with IR rat models. Interestingly, our findings also highlight the potential of both therapeutic agents for improving IR by regulating the liver PI3K/AKT pathway, reducing the deposition of hepatic TG, as well as upregulating the levels of SHBG and HNF-4α in PCOS with IR rat liver tissue.

Establishment of sex difference in circulating uric acid is associated with higher testosterone and lower sex hormone-binding globulin in adolescent boys.

Men have higher circulating levels of uric acid than women. This sex difference is suspected to be a result of suppressive effects of estradiol on uric acid. If so, estradiol would be inversely associated with circulating uric acid. This study aimed to test this hypothesis. This cross-sectional study included 9472 participants (weighted sample size of 184,342,210) aged 12-80 years from the 2013 to 2016 US National Health and Nutrition Examination Survey. Associations of sex hormones with uric acid were analyzed using weighted least squares regression, adjusting for demographic characteristics, lifestyle risk factors, and comorbidities. Neither free nor bioavailable estradiol was inversely associated with circulating uric acid in adolescent boys or girls, or adult men or women, or perimenopausal women after full adjustment. The sex difference in uric acid was established during adolescence as a result of a dramatic increase in uric acid in adolescent boys. During adolescence, the increase in estradiol in girls over time was accompanied by a relatively unchanged level of uric acid. All three fractions of estradiol (free, bioavailable, and total) were positively associated with uric acid in adolescent boys and girls after full adjustment. In adolescent boys, all three fractions of testosterone were positively associated with serum uric acid, and sex hormone-binding globulin was inversely associated with uric acid after full adjustment. These results suggest that estradiol is not inversely associated with circulating uric acid in adolescents and the establishment of sex difference in circulating uric acid during adolescence is associated with higher testosterone and lower sex hormone-binding globulin in adolescent boys.

SHBG as a Marker of NAFLD and Metabolic Impairments in Women Referred for Oligomenorrhea and/or Hirsutism and in Women With Sexual Dysfunction.

PCOS is one of the most common endocrine disorders and NAFLD is one of its most dangerous metabolic consequences. The diagnosis of NAFLD is not a practical task and the condition is at risk of being overlooked. The use of simpler but still reliable surrogate markers is necessary to identify women with a high likelihood of NAFLD. The aim of this study was to evaluate the clinical correlates of NAFLD Liver Fat Score (NAFLD-LFS) in women with oligomenorrhea and/or hirsutism. Furthermore, the study aimed to evaluate whether, among the hormonal parameters evaluated in such women, possible hallmarks of NAFLD may be identified. To this purpose, 66 women who attended our Outpatient Clinic for oligomenorrhea and/or hyperandrogenism were included in the study. In order to validate the results obtained in the first cohort, a second independent sample of 233 women evaluated for female sexual dysfunction (FSD) was analyzed. In cohort 1, NAFLD-LFS positively correlated with metabolic and inflammatory parameters. Among the hormone parameters, NAFLD-LFS showed no significant relationships with androgens but a significant negative correlation with SHBG (p<0.0001) that therefore appeared as a candidate hallmark for pathologic NAFLD-LFS. The ROC analysis showed a significant accuracy (81.1%, C.I.69.1-93.0, p <0.0001) for SHBG in identifying women with a pathological NAFLD-LFS. In particular, a SHBG 33.4 nmol/l was recognized as the best threshold, with a sensitivity of 73.3% and a specificity of 70.7%. In order to validate this SHBG as a marker of metabolic impairment possible related with the presence of NAFLD, we tested this threshold in cohort 2. FSD women with SHBG <33.4 nmol/l had worse metabolic parameters than women with SHBG ≥33.4 nmol/l and a significantly higher NAFLD-LFS even after adjusting for confounders (B=4.18 [2.05; 6.31], p=0.001). In conclusion, this study provides a new evidence in the diagnostic process of NAFLD, showing that the measurement of SHBG, which is routinely assessed in the workup of women referred for possible PCOS, could identify women at higher metabolic risk, thus detecting those who may deserve further targeted diagnostic assessment.

Associations of sex steroid hormones with mortality in women with breast cancer.

Epidemiological studies have demonstrated associations between circulating levels of sex steroid hormones and risk of breast cancer in postmenopausal women. However, data on associations with breast cancer survival are limited. We measured levels of estradiol, estrone, testosterone, and sex hormone-binding globulin (SHBG), in serum collected on average 30 months after diagnosis from 358 postmenopausal women diagnosed with stage I-IIIA breast cancer between 1995 and 1998 who participated in a multiethnic, prospective cohort study. Women were followed through December, 2012. We evaluated associations between log-transformed analytes and breast cancer-specific and all-cause mortality fitting multivariable Cox proportional hazards models. Over a median of 14.5 years of follow-up, 102 deaths occurred; 43 of these were due to breast cancer. In models adjusted for ethnicity/study site, age, body mass index, and tumor stage, increased levels of log-transformed SHBG were associated with reduced risk of both breast cancer-specific mortality (hazard ratio, HR 0.48; 95 % confidence interval, CI 0.26-0.89) and all-cause mortality (HR 0.64, 95 % CI 0.43-0.97). There were no associations between levels of estradiol, estrone, or testosterone for either endpoint. In subgroup analyses, after correction for multiple testing, increased estrone was significantly associated with reduced risk for breast cancer-specific mortality among participants with ER-negative tumors (HR 0.16, 95 % CI 0.05-0.63) but not among participants with ER-positive tumors. Increased serum levels of SHBG were associated with decreased risk of breast cancer-specific and all-cause mortality in women with breast cancer. These results should be confirmed in larger breast cancer survivor cohorts.

A Phase I/II Trial of BNC105P with Everolimus in Metastatic Renal Cell Carcinoma.

PURPOSE: BNC105P inhibits tubulin polymerization, and preclinical studies suggest possible synergy with everolimus. In this phase I/II study, efficacy and safety of the combination were explored in patients with metastatic renal cell carcinoma (mRCC). EXPERIMENTAL DESIGN: A phase I study in patients with clear cell mRCC and any prior number of therapies was conducted using a classical 3 + 3 design to evaluate standard doses of everolimus with increasing doses of BNC105P. At the recommended phase II dose (RP2D), patients with clear cell mRCC and one to two prior therapies (including ≥ 1 VEGF-TKI) were randomized to BNC105P with everolimus (arm A) or everolimus alone (arm B). The primary endpoint of the study was 6-month progression-free survival (6MPFS). Secondary endpoints included response rate, PFS, overall survival, and exploratory biomarker analyses. RESULTS: In the phase I study (N = 15), a dose of BNC105P at 16 mg/m(2) with everolimus at 10 mg daily was identified as the RP2D. In the phase II study, 139 patients were randomized, with 69 and 67 evaluable patients in arms A and B, respectively. 6MPFS was similar in the treatment arms (arm A: 33.82% vs. arm B: 30.30%, P = 0.66) and no difference in median PFS was observed (arm A: 4.7 mos vs. arm B: 4.1 mos; P = 0.49). Changes in matrix metalloproteinase-9, stem cell factor, sex hormone-binding globulin, and serum amyloid A protein were associated with clinical outcome with BNC105P. CONCLUSIONS: Although the primary endpoint was not met in an unselected population, correlative studies suggest several biomarkers that warrant further prospective evaluation.

Adiponectin upregulates SHBG production: molecular mechanisms and potential implications.

Epidemiological studies have shown that plasma SHBG levels correlate with plasma adiponectin levels, both in men and women. There are no reports describing any molecular mechanism by which adiponectin regulates hepatic SHBG production. The aim of the present study is to explore whether adiponectin regulates SHBG production by increasing HNF-4α levels through reducing hepatic lipid content. For this purpose, in vitro studies using human HepG2 cells, as well as human liver biopsies, were performed. Our results show that adiponectin treatment increased SHBG production via AMPK activation in HepG2 cells. Adiponectin treatment decreased the mRNA and protein levels of enzymes related to hepatic lipogenesis (ACC) and increased those related to fatty acid oxidation (ACOX and CPTI). These adiponectin-induced changes in hepatic enzymes resulted in a reduction of total TG and FFA and an increase of HNF-4α. When HNF-4α expression was silenced by using siRNA, adiponectin-induced SHBG overexpression was blocked. Furthermore, adiponectin-induced upregulation of SHBG production via HNF-4α overexpression was abrogated by the inhibition of fatty acid oxidation or by the induction of lipogenesis with a 30mM glucose treatment in HepG2 cells. Finally, adiponectin levels correlated positively and significantly with both HNF-4α and SHBG mRNA levels in human liver biopsies. Our results suggest for the first time that adiponectin increases SHBG production by activating AMPK, which reduces hepatic lipid content and increases HNF-4α levels.

Sperm parameters: paradigmatic index of good health and longevity.

Since the discovery of spermatozoon by Anton van Leeuwenhoek in 1677, there has been an ever increasing understanding of its role in reproduction. Many factors adversely affect sperm quality, including varicocele, accessory gland infection, immunological factors, congenital abnormalities, and iatrogenic systemic and endocrine causes, such as diabetes mellitus, obesity, metabolic syndrome, and smoking. The mechanisms responsible for the association between poor sperm parameters and ill health may include oxidative stress, low-grade inflammation, low testosterone, and low sex-hormone-binding globulin. Oxidative stress in the testicular microenvironment may result in decreased spermatogenesis and sperm DNA damage, loss of sperm motility, and abnormal sperm morphology. Low testosterone caused by advanced age, visceral obesity, and inflammation is associated with the development of cardiovascular disease. Hence, semen analysis has an important role in the routine evaluation of idiopathic male infertility, usually manifested as low sperm counts, impaired sperm motility, or absence of sperm, and remains the most common single diagnostic tool. Several studies have shown an inverse relationship between semen quality and medical disorders. This review elucidates the effect of medical disorders and social habits on sperm quality, the mechanisms that are involved in the impairment of sperm quality, and whether or not sperm quality can be used as an index of good health and longevity in a man.

Primordial germ cells (spermatogonial stem cells) of bullfrogs express sex hormone-binding globulin and steroid receptors during seasonal spermatogenesis.

In vertebrate species, testosterone seems to inhibit spermatogonial differentiation and proliferation. However, this androgen can also be converted, via aromatase, into estrogen which stimulates spermatogonial differentiation and mitotic activity. During seasonal spermatogenesis of adult bullfrogs Lithobates catesbeianus, primordial germ cells (PGCs) show enhanced testosterone cytoplasm immunoexpression in winter; however, in summer, weak or no testosterone immunolabelling was observed. The aim of this study was to confirm if PGCs express stem cell markers - alkaline phosphatase (AP) activity and GFRα1 (glial-cell-line-derived neurotrophic factor) - and verify whether testosterone is maintained in these cells by androgen receptors (ARs) and/or sex hormone-binding globulin (SHBG) in winter. Furthermore, regarding the possibility that testosterone is converted into estrogen by PGCs in summer, the immunoexpression of estrogen receptor (ER)ß was investigated. Bullfrog testes were collected in winter and in summer and were embedded in glycol methacrylate for morphological analyses or in paraffin for the histochemical detection of AP activity. GFRα1, AR, SHBG and ERß expression were detected by Western blot and immunohistochemical analyses. The expression of AP activity and GFRα1 in the PGCs suggest that these cells are spermatogonial stem cells. In winter, the cytoplasmic immunoexpression of ARs and SHBG in the PGCs indicates that testosterone is maintained by these proteins in these cells. The cytoplasmic immunoexpression of ERß, in summer, also points to an ER-mediated action of estrogen in PGCs. The results indicate a participation of testosterone and estrogen in the control of the primordial spermatogonia during the seasonal spermatogenesis of L. catesbeianus.

IL1ß down-regulation of sex hormone-binding globulin production by decreasing HNF-4α via MEK-1/2 and JNK MAPK pathways.

Patients suffering from low-grade chronic inflammatory diseases, such as rheumatoid arthritis, osteoarthritis, diabetes, and obesity, have low plasma sex hormone-binding globulin (SHBG) levels. These diseases are characterized among other features by high plasma IL1ß levels. The aim of the present study is to explore whether IL1ß could regulate hepatic SHBG production to account for low SHBG levels in these diseases. We provide evidence that daily IL1ß treatment reduces SHBG production in HepG2 cells by the down-regulation of HNF-4A via the MAPK kinase (MEK)-1/2 and c-Jun N-terminal kinase (JNK) MAPK signaling pathways through the activation c-Jun transcription factors. The human SHBG promoter sequence contains two putative activator protein 1 (AP1) binding sites recognized by c-Jun transcription factors, but they are not necessary for the IL1ß-induced down-regulation of SHBG promoter activity in luciferase reporter gene assays. Daily treatment with IL1ß reduces hepatic nuclear factor (HNF)-4α mRNA and protein levels via the MEK-1/2 and JNK MAPK signaling pathways. Moreover, IL1ß rapidly decreased HNF-4α mRNA and protein levels while increased phospho-c-Jun protein levels after the treatment. Finally, daily IL1ß treatment of human SHBG transgenic mice reduced plasma SHBG and SHBG mRNA levels. Moreover, IL1ß treatment also reduced HNF-4α mRNA and protein levels while increased hepatic phospho-c-Jun protein levels. Our results show that IL1ß reduces hepatic SHBG production by decreasing HNF-4α via MEK-1/2 and JNK MAPK pathways. In addition, our findings suggest that IL1ß could be involved the low plasma SHBG levels reported in chronic low-grade inflammatory diseases.

Testosterone is associated with erectile dysfunction: a cross-sectional study in Chinese men.

BACKGROUND: Testosterone is essential for the regulation of erectile physiology, but the relationship between low testosterone and erectile dysfunction (ED) has not been firmly established. PURPOSE: To examine the association between serum total, free and bio-available testosterone and ED in a population-based sample. METHODS: A consecutive series of 1776 men aged 20-77 participated in the routine physical examination from September 2009 to December 2009 in Guangxi, China. ED was assessed using the five-item International Index of Erectile Function (IIEF-5) questionnaire. Total testosterone (TT), sex hormone binding globulin (SHBG) and other biochemical profiles were measured. Free testosterone (FT) and bio-available testosterone (BT) were calculated based on Vermeulen's formula. Data were collected with regard to smoking, alcoholic drinking, physical activity and metabolic syndrome. RESULTS: The prevalence of ED (IIEF-5<22) was 47.6%. Men with ED were significantly older, and more prone to smoke cigarettes (≥20 cigarettes/day) or drink alcohol (≥3 drinks/week), and more likely to have elevated blood pressure (P = 0.036) or hyperglycemia (P<0.001) compared with those without ED. The significant increase in SHBG with age was parallel to its increase with increasing severity of ED (P<0.001). The obscure increase in TT across the ED status was detected without significance (P = 0.418), but TT was positively associated with ED after adjustment for age [odds ratio (OR)  = 1.02, 95% CI (confidence internal): 1.00-1.04]. FT and BT were inversely associated with ED (OR = 0.14, 95%CI: 0.06-0.33; OR = 0.92 (95%CI: 0.89-0.96, respectively) in the univariate analysis, and this inverse association appeared to be independent of smoking status, alcoholic drinking, physical activity, hyper-triglyceridemia and hyperglycemia. CONCLUSIONS: FT and BT are inversely related to worsening ED, whereas the positive association between TT and ED is most likely due to the increase in SHBG.

Reference ranges for total and calculated free and bioavailable testosterone in a young healthy women population with normal menstrual cycles or using oral contraception.

OBJECTIVE: Determine reference values for testosterone in women. DESIGN AND METHODS: 18-40 Year-old women with regular menses or using oral contraception were assessed by questionnaire and blood sample. RESULTS: In 155 women, reference values were different between women with and without hyperandrogenism for total testosterone (0.48-3.42 vs. 0.54-2.72 nmol/L) and calculated free (3-65 vs. 3-39 pmol/L) and bioavailable (0.06-1.35 vs. 0.06-0.81 nmol/L) testosterone. CONCLUSION: Upper reference values for testosterone in women must be established from a well-characterized population.

The ability of hydroxylated estrogens (2-OH-E2 and 4-OH-E2) to increase of SHBG gene, protein expression and intracellular levels in MCF-7 cells line.

OBJECTIVE: Sex Hormone-Binding Globulin (SHBG) - specific carrier for sex steroids - regulates hormone bioavailable fraction and estrogen signaling system in breast cancer cells. This study was conducted to elucidate the effects of hydroxylated estrogen (E2) metabolites (2-OH-E2 and 4-OH-E2) on sex hormone binding globulin (SHBG) mRNA and protein expression as well as on intracellular and extracellular SHBG levels. METHODS: MCF-7 human breast cancer cells were cultured with 2-OH-E2 or 4-OH-E2 in concentration of 1, 10 and 100 nM for 24 h, 17ß-estradiol being used as a positive control. SHBG levels were measured in medium and cells by ELISA, SHBG mRNA expression was evaluated by real-time-PCR and protein expression by Western blot analysis. RESULTS: 4-OH-E2 in high doses and 2-OH-E2 in the highest dose, while 17ß-estradiol in all doses used increased intracellular but not extracellular SHBG levels. Both metabolites increased SHBG mRNA expression, the rank order of potency being E2 > 4-OH-E2 > 2-OH-E2. Both E2 and its metabolites increased SHBG protein expression. CONCLUSION: Although the metabolites showed a lower potency than 17ß-estradiol, further studies are needed to clarify whether hydroxylated metabolites of E2 are potent ligands for SHBG.

Prostate cancer does not influence androgen levels: a radical prostatectomy cohort study.

AIM: To investigate the relationship between androgens and prostate cancer in patients scheduled for radical prostatectomy. SUBJECTS AND METHODS: Patients scheduled for open radical prostatectomy were enrolled. Blood samples were collected before prostate biopsy and 12 months later to evaluate testosterone, free testosterone, sex hormone-binding globulin (SHBG), PSA, calculated free and bioavailable testosterone. RESULTS: 44 patients were consecutively enrolled. 15 patients (34%) presented a Gleason score (GS) of 6, 24 patients GS 7 (54%), 1 patient (2%) GS 8, and 4 patients GS 9 (9%). Mean prostate cancer volume was 4.3 ± 5.7 cm(3). 24 patients presented a pT2 stage, 16 a pT3a stage, and 4 a pT3b stage. Positive surgical margins were detected in 12 patients (27.3%). No significant change of testosterone (4.21 ± 1.49 vs. 4.00 ± 1.48 ng/ml, p = 0.46), free testosterone (9.01 ± 3.64 vs. 8.85 ± 3.04 pg/ml, p = 0.83), SHBG (38 ± 14.39 vs. 38.5 ± 17.23 nmol/l, p = 0.71), calculated free testosterone (0.091 ± 0.13 vs. 0.067 ± 0.026, p = 0.563), and bioavailable testosterone (1.89 ± 0.722 vs. 1.88 ± 0.53, p = 0.912) was observed. CONCLUSIONS: In our single-center study, prostate cancer does not impact on serum androgen levels, however our results should be confirmed in a larger study.

Variants in the HMG-CoA reductase (HMGCR) gene influence component phenotypes in polycystic ovary syndrome.

OBJECTIVE: To study the role of genetic variation in the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (HMGCR) gene in polycystic ovary syndrome (PCOS). DESIGN: Women with and without PCOS were genotyped for seven single-nucleotide polymorphisms (SNPs) in HMGCR. The SNPs and haplotypes were determined and tested for association with PCOS and its component traits. SETTING: Subjects were recruited from the reproductive endocrinology clinic at the University of Alabama at Birmingham; control subjects were recruited from the surrounding community. Genotyping took place at Cedars-Sinai Medical Center in Los Angeles. PATIENT(S): A total of 287 white PCOS women and 187 control subjects were studied. INTERVENTION(S): Phenotypic and genotypic assessment. MAIN OUTCOME MEASURE(S): HMGCR genotype, PCOS diagnosis, androgen levels, metabolic traits. RESULT(S): No association with PCOS was observed. SNP rs4629571 was associated with increased insulin resistance. Haplotype 3 was associated with increased insulin resistance. Haplotype 5 was associated with higher SHBG and lower free T. CONCLUSION(S): Variation in the HMGCR gene may influence component features of PCOS, including insulin resistance, SHBG, and free T. HMGCR may thus act as a modifier gene in PCOS.

Associations between andrological measures, hormones and semen quality in fertile Australian men: inverse relationship between obesity and sperm output.

BACKGROUND: The World Health Organization developed a time to pregnancy (TTP) study (number of menstrual cycles taken to conceive) to determine whether the average TTP is increasing and semen quality decreasing with time. The present study describes clinical, semen and hormone characteristics obtained from male partners of pregnant women in Melbourne, Australia, and examines the associations between these characteristics. METHODS: Male partners (n = 225) of pregnant women (16-32 weeks) who conceived naturally had physical examination, health and lifestyle questionnaires, semen and hormone (FSH, LH, sex hormone-binding globulin, testosterone and Inhibin B) analyses. RESULTS: Previously known associations between semen, hormone and clinical variables were confirmed as significant: sperm numbers (concentration and total sperm count) correlated positively with Inhibin B and inversely with FSH and left varicocele, while total testicular volume correlated positively with sperm numbers and Inhibin B and inversely with FSH. However, only abstinence, total testicular volume, varicocele grade and obesity (BMI > 30 kg/m2) were independently significantly related to total sperm count. Compared with those with BMI < 30 (n = 188), obese subjects (n = 35) had significantly lower total sperm count (mean 324 versus 231 million, P = 0.013) and Inhibin B (187 versus 140 pg/ml, P < 0.001) but not FSH (3.4 versus 4.0 IU/l, P = 0.6). CONCLUSIONS: Obese fertile men appear to have reduced testicular function. Whether this is cause or effect, i.e. adiposity impairing spermatogenesis or reduced testicular function promoting fat deposition, remains to be determined.

Thyroid hormones act indirectly to increase sex hormone-binding globulin production by liver via hepatocyte nuclear factor-4alpha.

Thyroid hormones increase hepatic sex hormone-binding globulin (SHBG) production, which is also regulated by hepatocyte nuclear factor-4alpha (HNF-4alpha) in response to changes in the metabolic state of the liver. Since the human SHBG promoter lacks a typical thyroid hormone response element, and because thyroid hormones influence metabolic state, we set out to determine whether thyroid hormones mediate SHBG expression indirectly via changes in HNF-4alpha levels in HepG2 human hepatoblastoma cells, and in the livers of transgenic mice that express a 4.3 kb human SHBG transgene under the control of its own 0.8 kb promoter sequence. Thyroid hormones (triiodothyronine (T(3)) and thyroxine (T(4))) increase SHBG accumulation in HepG2 cell culture medium over 5 days, and increase cellular SHBG mRNA levels. In addition, T(4) treatment of HepG2 cells for 5 days increased HNF-4alpha mRNA and HNF-4alpha levels in concert with decreased cellular palmitate levels. Plasma SHBG levels were also increased in mice expressing a human SHBG transgene after 5 days treatment with T(3) along with increased hepatic HNF-4alpha levels. In HepG2 cells, the human SHBG promoter failed to respond acutely (within 24 h) to T(4) treatment, but a 4-day pre-treatment with T(4) resulted in a robust response that was prevented by co-treatment with HNF-4alpha siRNA, or by blocking the beta-oxidation of palmitate through co-treatment with the carnitine palmitoyltransferase I inhibitor, etomoxir. These data lead us to conclude that thyroid hormones increase SHBG production indirectly by increasing HNF-4alpha gene expression, and by reducing cellular palmitate levels that further contribute to increased HNF-4alpha levels in hepatocytes.

Molecular mechanisms of the D327N SHBG protective role on breast cancer development after estrogen exposure.

Sex Hormone-Binding Globulin, the specific carrier for sex steroids, regulates hormone bioavailable fraction and estrogen signaling system in breast cancer cells. A common single nucleotide polymorphism in the human SHBG gene results in an amino acid substitution (Asp327Asn), which introduces an additional N-glycosylation site, and is associated with reduced breast cancer risk in postmenopausal women. The frequency of this polymorphism was evaluated in a group of patients that developed breast cancer while taking hormonal replacement therapy (HRT) for menopause, an interesting model of estrogen exposure. The polymorphism frequency was significantly higher in women taking HRT that didn't develop any breast cancer than in breast cancer patients (P<0.05). To get insight into the underlying mechanisms, we compared the ability of recombinant wild type and variant (D327N) SHBG to influence estradiol effects in MCF-7 breast cancer cells. D327N SHBG was more effective than wild type protein in inhibiting estradiol-induced cell proliferation and anti-apoptosis. This depended on the fact that D327N SHBG binding to MCF-7 cells was significantly higher than that of wild type protein. As a consequence, D327N caused a larger induction of the second messenger cAMP and a deeper inhibition of the estradiol-induced Erk (1/2) phosphorylation. Our observations, demonstrating the increased efficiency of D327N SHBG in counteracting estradiol action and a significantly higher frequency of Asp327Asn polymorphism in women not developing breast cancer after estrogen exposure, first provide evidence for the mechanism of D327N SHBG protective action.

Sex hormones, sex hormone binding globulin, and abdominal aortic calcification in women and men in the multi-ethnic study of atherosclerosis (MESA).

BACKGROUND: Conflicting findings exist regarding the associations of sex hormones with subclinical atherosclerosis. METHODS: This is a substudy from MESA of 881 postmenopausal women and 978 men who had both abdominal aortic calcification (AAC) quantified by computed tomography and sex hormone levels assessed [Testosterone (T), estradiol (E2), dehydroepiandrosterone (DHEA), and sex hormone binding globulin (SHBG)]. We examined the association of sex hormones with presence and extent of AAC. RESULTS: For women, SHBG was inversely associated with both AAC presence [OR=0.62, 95% CI 0.42-0.91 for 1 unit greater log(SHBG) level] and extent [0.29 lower log(AAC) for 1 unit greater log(SHBG) level, beta=-0.29 (95% CI -0.57 to -0.006)] adjusting for age, race, hypertension, smoking, diabetes, BMI, physical activity, and other sex hormones. After further adjustment for total and HDL-cholesterol, SHBG was not associated with ACC presence or extent. In men, there was no association between SHBG and AAC. In both men and women, neither T, E2, nor DHEA was associated with AAC presence or extent. CONCLUSION: After adjustment for non-lipid cardiovascular risk factors, SHBG levels are inversely associated with both the presence and severity of AAC in women but not in men, which may be accounted for by HDL.

Polycystic ovary syndrome in obese adolescents.

PURPOSE OF REVIEW: As the prevalence of pediatric obesity escalates, polycystic ovary syndrome is an increasingly common morbidity for adolescent females. This review describes recent insights into the pathophysiology and treatment of polycystic ovary syndrome, with special attention given to the relationship between polycystic ovary syndrome and obesity. RECENT FINDINGS: Recent research has elucidated three key concepts in our understanding of polycystic ovary syndrome. First, patients may enter the hyperandrogenism-hyperinsulinism cycle of polycystic ovary syndrome via several pathways, including genetic polymorphisms that affect androgen synthesis, fetal programming that alters lipid and glucose metabolism, and obesity accompanied by insulin resistance. Second, obesity plays a significant role in the pathophysiology of polycystic ovary syndrome by increasing free androgen concentrations through multiple mechanisms. Finally, just as the etiology of polycystic ovary syndrome is multifactorial, successful treatment will probably require a combination of lifestyle modification and therapeutic interventions. SUMMARY: Obesity contributes to the pathophysiology of polycystic ovary syndrome and increases the likelihood of associated metabolic and cardiovascular morbidities.

Monosaccharide-induced lipogenesis regulates the human hepatic sex hormone-binding globulin gene.

The liver produces plasma sex hormone-binding globulin (SHBG), which transports sex steroids and regulates their access to tissues. In overweight children and adults, low plasma SHBG levels are a biomarker of the metabolic syndrome and its associated pathologies. Here, we showed in transgenic mice and HepG2 hepatoblastoma cells that monosaccharides (glucose and fructose) reduce human SHBG production by hepatocytes. This occurred via a downregulation of hepatocyte nuclear factor-4alpha (HNF-4alpha) and replacement of HNF-4alpha by the chicken OVA upstream promoter-transcription factor 1 at a cis-element within the human SHBG promoter, coincident with repression of its transcriptional activity. The dose-dependent reduction of HNF-4alpha levels in HepG2 cells after treatment with glucose or fructose occurred in concert with parallel increases in cellular palmitate levels and could be mimicked by treatment with palmitoyl-CoA. Moreover, inhibition of lipogenesis prevented monosaccharide-induced downregulation of HNF-4alpha and reduced SHBG expression in HepG2 cells. Thus, monosaccharide-induced lipogenesis reduced hepatic HNF-4alpha levels, which in turn attenuated SHBG expression. This provides a biological explanation for why SHBG is a sensitive biomarker of the metabolic syndrome and the metabolic disturbances associated with increased fructose consumption.