The relationship between aromatase activity and body fat distribution

The levels of adipokines in relation to hormonal changes during the menstrual cycle in young, normal-weight women

CONTEXT

The aim of this study was to assess the plasma leptin, adiponectin, resistin, visfatin/NAMPT, omentin-1, vaspin, apelin, TNF-α, IL-6 and RBP4 levels in relation to hormonal changes during the menstrual cycle in young, healthy, normal-weight women.

METHODS

The study involved 52 young, healthy, normal-weight women. Anthropometric parameters, body composition and levels of plasma leptin, adiponectin, resistin, visfatin/NAMPT, omentin-1, vaspin, apelin, TNF-α, IL-6 and RBP4 in addition to serum FSH, LH, estradiol, progesterone, 17-OH progesterone, androgens, SHBG and insulin concentrations were measured during a morning in fasting state three times: between days 2-4, days 12-14 and days 24-26 of the menstrual cycle.

RESULTS

Plasma adiponectin, omentin-1, resistin and visfatin/NAMPT, apelin, TNF-α, IL-6 and RBP4 concentrations were stable during the menstrual cycle, while leptin and vaspin levels were significantly higher in both the midcycle and the luteal phases than those in the follicular phase. Multivariate regression analyses revealed that changes in leptin and vaspin levels between the follicular and the luteal phase are strongly related to changes in total testosterone levels.

CONCLUSIONS

Our results revealed stable levels of adipokines during the phases of the physiological menstrual cycle, except for leptin and vaspin, which showed increased levels in both the midcycle and the luteal phases. This effect was significantly associated with changes in the secretion of testosterone, 17-OH progesterone and insulin in the luteal phase.

Sex hormones and macronutrient metabolism

The biological differences between males and females are determined by a different set of genes and by a different reactivity to environmental stimuli, including the diet, in general. These differences are further emphasized and driven by the exposure to a different hormone flux throughout the life.

These differences have not been taken into appropriate consideration by the scientific community. Nutritional sciences are not immune from this “bias” and when nutritional needs are concerned, females are considered only when pregnant, lactating or when their hormonal profile is returning back to “normal,” i.e., to the male-like profile.

The authors highlight some of the most evident differences in aspects of biology that are associated with nutrition.

This review presents and describes available data addressing differences and similarities of the “reference man” vs. the “reference woman” in term of metabolic activity and nutritional needs. According to this assumption, available evidences of sex-associated differences of specific biochemical pathways involved in substrate metabolism are reported and discussed. The modulation by sexual hormones affecting glucose, amino acid and protein metabolism and the metabolization of nutritional fats and the distribution of fat depots, is considered targeting a tentative starting up background for a gender concerned nutritional science.

No Increase in Female Breast Size or Fat Redistribution to the Upper Body After Liposuction: A Prospective Controlled Photometric Study

BACKGROUND

Some studies have indicated that liposuction may cause breast enlargement. Fat redistribution to the upper body as a compensatory mechanism after liposuction has also been reported.

OBJECTIVES

To evaluate the possibility of secondary breast hypertrophy and fat redistribution after liposuction, breast size and upper body measurements were obtained and compared for women who did not gain weight postoperatively.

METHODS

Eighty-two women who underwent cosmetic surgery, not including breast surgery, were enrolled in this prospective controlled study. Participants represented 1 of 3 procedure groups: cosmetic surgery not including liposuction (n = 24), liposuction (n = 41), and liposuction combined with abdominoplasty (n = 17). Breast measurements were obtained from standardized lateral photographs matched for size and orientation. Results were compared among the study groups.

RESULTS

Postoperatively, there were no significant changes in mean body weight among the study groups. No significant increases in upper pole projection, breast projection, or breast area were found in patients treated with liposuction alone and those who received liposuction plus abdominoplasty. Upper body dimensions were unchanged except for a significant (P < .01) decrease in upper abdominal width in women treated with liposuction plus abdominoplasty. The findings were the same for a subset of 17 women with liposuction aspirate volumes >1500 mL.

CONCLUSIONS

Results indicate that neither liposuction nor abdominoplasty produces secondary breast enlargement. Upper body dimensions are unchanged, consistent with findings of a previous study and contrary to the theory of fat redistribution.

LEVEL OF EVIDENCE

2.

Hormonal and metabolic modulation through nutrition: towards a primary prevention of breast cancer

Breast cancer (BC) is a polygenic and multifactorial disease for which estrogens have been recognized as the main risk factor, and for which lifestyle plays a key role. Previous epidemiologic cancer research performed in Uruguayan population delimited its dietary and anthropometric profiles. Recognizing the difficulty for universalizing a nutritional basis for prevention due to different eating patterns among regions and countries, we summarize the existent knowledge linking nutrition, estrogens, metabolism and BC. As an attempt towards primary prevention of BC, we present recommendations mainly based on country-specific research findings and modifiable putative risk and protective factors, proposing to modify the intake of meats and other fatty foods--especially sources of Ω-6 and Ω-3 fatty acids--adding olive oil, selected vegetables, citrus fruits and working towards adequate body fat/muscle proportions. From a medical and ethical viewpoint, it is justified to recommend certain nutritional changes to women, because no adverse side effects are expected to occur.

Somatotype and risk of breast cancer: a case-control study in Uruguay

According to the evidence, there is a need for more thorough assessment and quantification of body size and shape and the risk of breast cancer. Using the somatotype methodology, we carried out an original research in order to explore possible associations between body shape and the risk of breast cancer in Uruguayan women. With this objective, 254 recent breast cancer cases and 1,000 frequency-matched healthy controls were interviewed on menstrual and reproductive story, and a series of skinfolds, circumferences and diameters were measured specifically to calculate somatotype. A positive association with breast cancer was found for high endomorphy (Odds Ratio [OR] = 2.82, p < 0.001), mainly among pre-menopausal women (OR = 4.98, p <0.001) and normoweight women (OR = 5.12, p = 0.002), whereas almost no differences were observed for mesomorphic and ectomorphic women. Analysis showed a high meso-endomorphic pattern in the study population. Further studies are needed to confirm the present results obtained in a country with high incidence of the disease.

Adiposity, the metabolic syndrome, and breast cancer in African-American and white American women

Breast cancer, the second most common cause of cancer-related deaths in American women, varies substantially in incidence and mortality according to race and ethnicity in the United States. Although the overall incidence of breast cancer among African-American (AA) women is lower than in white American women, this cancer is more common in young premenopausal AA women, and AA breast cancer patients of all ages are more likely to have advanced disease at diagnosis, higher risk of recurrence, and poorer overall prognosis. Epidemiological studies indicate that these differences may be attributable in part to variation in obesity and body fat distribution. Additionally, AA women more frequently exhibit breast cancer with an aggressive and metastatic phenotype that may also be attributable to the endocrine and metabolic changes associated with upper body obesity. These changes include both elevated estrogen and androgen bioactivity, hyperinsulinemia, and perturbations of the adipokines. Type 2 diabetes and the metabolic syndrome, which are more common in AA women, have also been associated with breast cancer risk. Moreover, each of the individual components of the syndrome has been associated with increased breast cancer risk, including low levels of the adipocytokine, adiponectin. This review explores the specific roles of obesity, body fat distribution (particularly visceral and sc adipose tissue), type 2 diabetes, metabolic syndrome, and adipocytokines in explaining the differential patterns of breast cancer risk and prognosis between AA and white American women.

Relationship of plasma adiponectin with sex hormone and insulin-like growth factor levels

OBJECTIVE

Recent studies have suggested that a relationship between adiponectin and sex hormone, prolactin, and insulin-like growth factor levels could be important for breast cancer risk and insulin sensitivity. Therefore, we assessed the relationship of adiponectin with plasma concentrations of estrone; estradiol; estrone sulfate; testosterone; androstenedione; dehydroepiandrosterone (DHEA); dehydroepiandrosterone sulfate (DHEAS); sex hormone binding globulin (SHBG); prolactin; insulin-like growth factor (IGF-1); its binding protein, IGF binding protein 3 (IGFBP-3); c-peptide; and IGF binding protein 1 (IGFBP-1) among 360 postmenopausal women not taking postmenopausal hormones from the Nurses' Health Study.

RESEARCH METHODS AND PROCEDURES

Multivariate models were adjusted for physical activity, alcohol consumption, age at blood draw, age at first birth/parity, fasting status, and time of day of blood draw; a separate model was additionally adjusted for BMI at blood draw.

RESULTS

Estrogens were inversely associated with adiponectin levels; however, except for free estradiol, these associations were substantially attenuated after adjustment for BMI. Free estradiol levels were 27% lower among women in the top vs. bottom quartile of adiponectin levels. No consistent associations were observed for the androgens, prolactin, IGF-1, and IGFBP-3. However, SHBG, c-peptide, and IGFBP-1 were strongly and independently associated with adiponectin levels (r = 0.29, -0.30, 0.24, respectively).

CONCLUSION

With the exceptions of SHBG, c-peptide, and IGFBP-1, the studied analytes were modestly associated with adiponectin and the associations were, in large part, mediated by body fat.

Genotype-specific weight loss treatment advice: how close are we?

Obesity, whose prevalence is continually rising, is one of the world’s greatest health care burdens. This multifactorial condition is associated with many obesity-related conditions, such as type 2 diabetes, dyslipidemia, and cardiovascular disease. Weight loss is a significant challenge facing those wishing to reduce their disease risk. Of course, like obesity itself, weight loss is a complex phenomenon dependent on many environmental and genetic influences, and thus individual responses to weight loss interventions are incredibly variable. Currently, there are 3 major interventions used to reduce weight: diet, exercise, and pharmacotherapy. The findings from studies examining gene–diet (nutrigenetic), gene–exercise (actigenetic), and gene–pharmaceutical (pharmacogenetic) interactions, although not clinically applicable at this time, are gaining awareness. This review article summarizes the current evidence to support the contribution of DNA sequence variation in genes related to energy balance (expenditure and intake) in the response to weight loss intervention. There is no doubt that replication using more rigorous study designs that include the study of interactions between multiple genes and interventions is required to move towards the development of genotype-specific weight loss treatment strategies.

CYP19A1 genetic polymorphisms may be associated with obesity-related phenotypes in Chinese women

OBJECTIVE

To examine the relationship between genetic polymorphisms of the CYP19A1 gene and obesity-related phenotypes, body mass index (BMI) and waist-to-hip ratio (WHR).

SUBJECTS

In total, 1241 Chinese women, who were recruited as community controls for a population-based case-control study of breast cancer.

METHODS

Nineteen haplotype tagging single nucleotide polymorphisms (htSNPs) in four haplotype blocks were genotyped.

RESULTS

Significant associations were observed for WHR at three SNPs that are located in haplotype block 1, including rs2445765, rs1004984 and rs1902584 (P=0.05, 0.04 and 0.01, respectively). Women, particularly premenopausal women, who carried the minor allele at any of these SNPs, had higher WHR than those without it. Of these three SNPs, the strongest association was observed at rs1902584, which is the closest to Promoter I.4, the major promoter for adipose tissue. Haplotype analyses indicated an association between the haplotype TCCAT in block 1 and WHR with a P-value of 0.02.

CONCLUSION

These results suggested that CYP19A1 genetic polymorphisms may be associated with the risk of obesity among Chinese women, especially among premenopausal women. The CYP19A1 protein (aromatase) plays a critical role in estrogen biosynthesis and thus affects body fat distribution and regulation.

Breast enlargement after liposuction: comparison of incidence between power liposuction versus traditional liposuction

BACKGROUND

We previously reported that a significant percentage of patients who underwent power liposuction noted an increase in their breast size.

OBJECTIVE

To determine whether the documented observation of breast enlargement after power liposuction also occurs after traditional liposuction.

METHODS

Charts were retrospectively reviewed and patient interviews were conducted for 70 female patients who had traditional liposuction. Analyses were made based on several factors, including age, pre- and postoperative weight, total fat aspirate volume, treated body areas, and hormonal medications for patients who did and did not have breast enlargement. These results were then compared with patients who experienced an increase in breast size after power, liposuction.

RESULTS

Thirty-seven percent of the study patients (26 of 70) undergoing traditional liposuction reported an increase in breast size. Sixty-five percent of these women (17 of 26) reported an increase of one or more cup sizes. Larger fat aspirate volumes and liposuction of the abdomen and hip or abdomen, hip, and thigh areas were factors associated with the patients who noted breast enlargement after traditional liposuction.

CONCLUSIONS

An increase in breast size was reported in 37% of patients after traditional liposuction and in 34% of patients after power liposuction. We conclude that breast enlargement after both traditional and power liposuction is not related to the mechanical effects of power liposuction. We propose the same hypothesis reported in our previous study that an altered androgen to estrogen ratio after liposuction is likely responsible for this noted occurrence. Weight gain may also be a factor.

The effect of CYP19 and COMT polymorphisms on exercise-induced fat loss in postmenopausal women

OBJECTIVE

To examine whether genetic polymorphisms in CYP19 [intron 4 (TTTA)n; n = 7 to 13 and a 3-base pair deletion, which is in strong linkage disequilibrium with the seven repeat] and COMT (Val108/158Met) modified the change in BMI, total and percentage body fat, or subcutaneous and intra-abdominal fat during a year-long exercise intervention trial. These genes metabolize estrogens and androgens, which are important in body fat regulation.

RESEARCH METHODS AND PROCEDURES

A randomized intervention trial was used, with an intervention goal of 225 min/wk of moderate-intensity exercise for one year. Participants (n = 173) were postmenopausal, 50 to 75 years old, sedentary, overweight or obese, and not taking hormone therapy at baseline.

RESULTS

Exercisers with two vs. no CYP19 11-repeat alleles had a larger decrease in total fat (-3.1 kg vs. -0.5 kg, respectively, p = 0.01) and percentage body fat (-2.4% vs. -0.6%, respectively, p = 0.001). Exercisers with the COMT Met/Met vs. Val/Val genotype had a smaller decrease in percentage fat (-0.7% vs. -1.9%, respectively, p = 0.05). Among exercisers, women with the COMT Val/Val genotype and at least one copy of the CYP19 11-repeat allele vs. those with neither genotype/allele had a significantly larger decrease in BMI (-1.0 vs. +0.1 kg/m2, respectively, p = 0.009), total fat (-2.9 vs. -0.5 kg, respectively, p = 0.004), and percentage body fat (-2.6% vs. -0.4%, respectively, p < 0.001).

DISCUSSION

Genetic polymorphisms in CYP19 and COMT may be important for body fat regulation and possibly modify the effect of exercise on fat loss in postmenopausal women.

Effects of a Moderate Intensity Exercise Intervention on Estrogen Metabolism in Postmenopausal Women

Physical activity has been associated with reduced breast cancer risk, potentially via hormonal pathways, and high urinary excretion of 2-hydroxyestrone (2-OH E1) relative to 16α-hydroxyestrone (16α-OH E1) also has been associated with reduced breast cancer risk. Studies suggest that body composition and exercise can influence estrogen metabolism. We determined the effects of a 12-month moderate intensity aerobic exercise intervention on urinary 2-OH E1, 16α-OH E1, and their ratio in overweight and obese, previously sedentary, postmenopausal women, ages 50–75 years. Women were randomized to a 12-month exercise intervention (n = 87) or stretching control group (n = 86); 170 completed the study. Urinary 2- and 16α-OH E1 were measured in spot urines collected at baseline, 3, and 12 months. Body composition was measured at baseline and 12 months. Differences between exercisers and controls for excretion of estrogen metabolites were determined using general estimating equations. Further analyses assessed change in estrogen metabolites and their ratio by subgroups of change in body composition. Overall, there were no significant effects of the exercise intervention on 2-OH E1, 16α-OH E1, or their ratio (P &gt; 0.05). There appeared to be an effect of change in intra-abdominal fat and adherence to the exercise intervention on change in the estrogen metabolites or their ratio. However, this did not reflect a potentially desirable change in estrogen metabolites associated with the exercise intervention. Thus, this 12-month moderate intensity exercise intervention did not significantly alter urinary excretion of 2-OH E1, 16α-OH E1, or their ratio in this population of women.

Biological rationale for endocrine therapy in breast cancer

Oestrogens are heavily implicated in the risk to, and progression of, breast cancer. Therapeutic strategies targeted at the oestrogenic stimulus to the breast and hormone-sensitive breast cancers are extremely attractive measures both to prevent the disease and to treat established tumours. The present review outlines the biological rationale for such endocrine therapy and traces the evolution whereby irreversible surgical procedures have been replaced by potent and specific drugs. In particular, the development of the latest generation of agents which inhibit oestrogen biosynthesis (aromatase inhibitors) is considered by defining the central role of the aromatase enzyme, its regulation and contribution to circulating and tumour endogenous oestrogens. The nature of response and resistance which may be elicited following the use of endocrine therapy is also described as this may determine the optimal use of aromatase inhibitors and, more generally, anti-hormone therapy in the management of women at high risk to, or with, breast cancer.

Testosterone levels in obese male patients with obstructive sleep apnea syndrome: relation to oxygen desaturation, body weight, fat distribution and the metabolic parameters

To investigate the impact of obstructive sleep apnea syndrome (OSAS) on testosterone levels and on the main parameters of the metabolic syndrome in abdominally obese men, 15 male subjects with abdominal obesity phenotype and polysomnographic diagnosis of OSAS (OB-OSAS) and 15 controls matched for age and anthropometric parameters (OB) were investigated. Anthropometry, SHBG, sex hormones and several parameters of the metabolic syndrome were measured. Only subjects with an Epworth Sleepiness Score greater than 10 underwent a polysomnographic study with calculation of the number of desaturation rates per sleeping hour (ODI), the minimal oxygen saturation during each desaturation episode (minSaO2) and the mean minimal arterial oxygen saturation for the whole night period (MminSaO2). Both total and free testosterone levels were lower in OB-OSAS than in OB patients. A negative correlation between polysomnographic parameters (ODI, minSaO2 and MminSaO2) and testosterone levels was found. The relationship between total and free testosterone and ODI persisted after adjusting for body mass index (BMI) and waist (W) values. Triglyceride and uric acid levels were significantly higher in OB-OSAS than in OB patients. A negative correlation between testosterone and acid uric level and a positive correlation between testosterone and HDL-cholesterol level was found, regardless of BMI and W circumference, particularly in the OB-OSAS group. Our study suggests that, in patients with obesity and OSAS, the severity of hypoxia during sleeping hours may be an additional factor in reducing testosterone levels, regardless of BMI and abdominal fatness. This may contribute in worsening metabolic abnormalities which, in men with OSAS, exceed those expected on the basis of degree of obesity and pattern of fat distribution.

Breast enlargement observed after power liposuction: a retrospective review

BACKGROUND

After undergoing power liposuction to various body areas, a significant number of subjects reported an increase in their breast size that occurred spontaneously several months after their procedure.

OBJECTIVE

To establish the incidence of breast enlargement among subjects who underwent power liposuction and to identify variables that are associated with the phenomenon.

METHODS

A retrospective chart review and patient interview were performed from among 73 subjects who had undergone power liposuction at our center. Variables such as age, original weight, volume of aspirated fat, estrogen supplements, amount of weight loss or gain, and body areas aspirated were compared between those who experienced breast enlargement and those who did not.

RESULTS

Thirty-four percent of the subjects (25 of 73) reported an increase in breast size. Of this group, 32% (8 of 25) reported an increase in cup size of one or more. Variables associated with the cohort who experienced breast enlargement included larger volume of fat aspiration and liposuction in the abdomen and hip location.

CONCLUSION

Breast enlargement was observed in 34% of the subjects after power liposuction either in the form of a larger bra cup size or a subjective feeling of increased fullness. We hypothesize that an altered androgen to estrogen ratio after liposuction may be responsible for this change.

Catalytic differences between porcine blastocyst and placental aromatase isozymes

Two isozymes of porcine aromatase, the placental and the blastocyst forms, were expressed in CHO cells using the mammalian cell transfection method. Using an 'in-cell' assay (a 3H-water release method), catalytic parameters of the porcine placental aromatase were found to be very similar to those of the human enzyme; however, the activity of the blastocyst isozyme was found to be one-thirtieth that of the placental isozyme. Product isolation assay (using testosterone as the substrate) revealed that the major steroid products were 17beta-estradiol and 19-nortestosterone. The product ratio of estradiol/19-nortestosterone was found to be 94 : 6 for the porcine placental form, 6 : 94 for the porcine blastocyst form, and 92 : 8 for the human wild-type aromatase. Therefore, the porcine blastocyst aromatase isozyme catalyzes mainly androgen 19-desmethylation rather than aromatization. In addition, inhibition profile analyses on the placental and blastocyst isozymes were performed using three steroidal inhibitors [4-hydroxyandro-stenedione (4-OHA), 7alpha-(4'-amino)phenylthio-1, 4-androstandiene-3,17-dione (7alpha-APTADD), and bridge (2, 19-methyleneoxy) androstene-3,17-dione (MDL 101,003)], and four nonsteroidal inhibitors [aminoglutethimide (AG), CGS 20267, ICI D1033, and vorozole (R83842)]. While the two isozymes of porcine aromatase share 93% amino-acid sequence identity, our results indicate that the two porcine aromatase isozymes have distinct responses to various aromatase inhibitors.

Biology of aromatase in the mammary gland

While the ovaries are the principal source of systemic estrogen in the premenopausal nonpregnant woman, other sites of estrogen biosynthesis are present throughout the body and these become the major sources of estrogen beyond menopause. These sites include the mesenchymal cells of the adipose tissue and skin, osteoblasts, and perhaps chondrocytes in bone, vascular endothelial and aortic smooth muscle cells, as well as a number of sites in the brain including the medial preoptic/anterior hypothalamus, the medial basal hypothalamus and the amygdala. These extragonadal sites of estrogen biosynthesis possess several fundamental features which differ from those of the ovaries. Principally, the estrogen synthesized within these compartments is probably only biologically active at a local tissue level in a paracrine or 'intracrine' fashion. Thus the total amount of estrogen synthesized by these extragonadal sites may be small, but the local tissue concentrations achieved are probably quite high, and exert significant biological influence locally. Thus these sources of estrogen play an important but hitherto largely unrecognized, physiological and pathophysiological role.

Impaired ovulation and breast cancer risk

Conflicting results have been reported on the association between breast cancer risk and symptoms of luteal insufficiency, such as irregular or prolonged menstrual cycles and difficulty in becoming pregnant. Studies on the association between breast cancer risk and hormonal markers of impaired ovulation have also yielded conflicting results. Inadequate allowance for body mass and fat distribution may lead to inconsistent results when assessing the association between luteal insufficiency in premenopausal women and breast cancer risk. Ovulatory function is impaired by obesity, especially if it is predominantly abdominal in distribution. The Western diet and lifestyle favour early manifestation of hyperinsulinaemic insulin resistance in genetically-predisposed women. It is commonly associated with obesity which is predominantly abdominal in distribution. In a subset of premenopausal women, the concomitants of hyperinsulinaemia may impair maturation of ovarian follicles by a direct effect of insulin or insulin-like growth factors on ovarian tissue. Even when women are ovulating regularly, obesity may be associated with luteal insufficiency as shown by decreased levels of progestins or other changes in the sex steroid profile. Insulin resistance is likely to be involved and might explain the weak reduction in breast cancer risk associated with overweight in premenopausal Western women, in contrast with the increased risk widely reported in obese post menopausal women.

Effects of acute hyperinsulinemia on testosterone serum concentrations in adult obese and normal-weight men

In a previous study performed in adult obese and normal-weight male subjects, we found that suppression of insulin levels by diazoxide reduced testosterone and increased sex hormone-binding globulin (SHBG) blood concentrations. These and other data suggested that insulin may have a regulatory capacity in testosterone secretion and/or metabolism in men, similar to what has already been demonstrated in women. In this study, we investigated the effects of acute hyperinsulinemia on major androgen levels, including testosterone, in two groups of normal-weight in = 11) and obese (n = 9) men. Acute hyperinsulinemia was obtained by the euglycemic-hyperinsulinemic clamp technique. Relationships between the degree of insulin resistance (ie, total glucose disposal [M value]) and testosterone levels were also evaluated. Basal testosterone levels in obese subjects (10.40 +/- 3.02 nmol/L) were significantly lower than in normal-weight controls (15.50 +/- 4.65 nmol/L, P < .01), whereas no difference was present in androstenedione and dehydroepiandrosterone sulfate (DHEA-S) concentrations. During the clamp study, testosterone was significantly increased in the obese group (11.79 +/- 3.64 nmol/L, P < .05) but not in the control group (15.81 +/- 4.54 nmol/L, P = NS). The other two androgens did not significantly change in either the obese or control group. There was a highly significant correlation between baseline testosterone concentrations, with M values suggesting a relationship between impaired peripheral insulin sensitivity and reduced plasma testosterone concentrations. It should be pointed out that there was a certain discrepancy in the testosterone variations, particularly in the control group, in which two thirds of the subjects had no change or some decrease in testosterone levels, whereas in the remainder testosterone increased over the values of the assay variation coefficient. These findings are consistent with the hypothesis that insulin may regulate testosterone blood levels also in male subjects. Whether these effects are primarily due to increased hormone secretion or reduced clearance needs to be investigated.

11 beta-Hydroxysteroid dehydrogenase 1 activity and gene expression in human adipose stromal cells: effect on aromatase activity

The biological activity of glucocorticoids in target tissues can be influenced by locally produced 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD), the enzyme responsible for the interconversion of cortisol and its inactive metabolite cortisone. In human adipose stromal cells, glucocorticoids are potent stimulators of the conversion of androgens to estrogens (aromatase activity). The present study was designed to determine whether 11 beta-HSD activity was present in human adipose stromal cells, and if changes in the activity of this enzyme could influence aromatase activity. 11 beta-HSD activity was determined by a radiometric conversion assay in breast adipose tissue from six patients. It was found that both dehydrogenase (cortisol to cortisone) and reductase (cortisone to cortisol) activities were present in all six subjects, and the reductase activity was always predominant. Carbenoxolone (CBX), a potent inhibitor of 11 beta-HSD, added to the culture medium at 50 and 200 microM, resulted in 39 +/- 4% and 85 +/- 1% inhibition, respectively, of both reductase and dehydrogenase activity of 11 beta-HSD. To determine whether alterations in 11 beta-HSD could influence aromatase activity, the effect of CBX (200 microM) on cortisol- and cortisone-induced changes in the conversion of androstenedione to estrone was examined. CBX prevented the stimulatory effect of cortisone and minimally potentiated the stimulatory effect of cortisol on aromatase activity, reflecting an inhibition of the local activation of cortisone and the local metabolism of cortisol, respectively. In order to determine whether the product of the 11 beta-HSD 1 gene was responsible for the observed 11 beta-HSD activity, total RNA extracts from these cells were subjected to Northern blot analysis using human 11 beta-HSD 1 cDNA as the probe. A single 1.8 11 beta-HSD 1 transcript was detected, and its abundance was reduced by CBX. No 11 beta-HSD 2 mRNA was detected. The present results demonstrate that the 11 beta-HSD 1 gene is expressed and functional in human breast adipose stromal cells and that changes in 11 beta-HSD 1 activity result in alterations in aromatase activity.

Aromatase gene expression and its exon I usage in human breast tumors. Detection of aromatase messenger RNA by reverse transcription-polymerase chain reaction

The expression of aromatase in human breast tumors has been studied by the reverse-transcription polymerase chain reaction (RT-PCR) method on 70 breast tissue specimens. An RT-PCR analysis using two oligonucleotide primers derived from the exon II of the human aromatase gene revealed that aromatase mRNA was detected in all but three tissue specimens. Furthermore, primer-directed RT-PCR was performed to determine the exon I usage in aromatase mRNA in these breast tumor specimens. The analysis has revealed that exons I.3 and PII are the two major exon Is present in aromatase mRNA isolated from breast tumors, suggesting that promoters I.3 and II are the major promoters driving aromatase expression in breast cancer and surrounding adipose stromal cells. The RT-PCR analysis also detected two products, I.3A (334 bp in length) and I.3B (222 bp in length), when it was carried out using a primer derived from exon I.3 and a reverse primer derived from exon II. The nucleotide sequences of these products have been determined and indicate that I.3A contains a region which was previously thought to be an intron. In addition, RT-PCR analyses of RNA isolated from eight pairs of breast tumor and neighboring normal tissue specimens were performed to evaluate the exon I usage and the distribution of I.3A- and I.3B-containing aromatase RNA messages in breast tumor and neighboring normal tissues. The results suggest that I.3B- and I.3A-containing messages are mainly present in breast tumor and neighboring normal tissues, respectively. Finally, the exon I/promoter usage for aromatase expression in eight cell lines (skin fibroblast, MCF-7, MDA-MB-231, T-47D, SK-BR-3, JAR, OVCAR-3, and human adipose stromal cells) was examined by primer-directed RT-PCR analyses. These studies provide a basis for further evaluation of the control mechanism of aromatase expression and estrogen biosynthesis in breast tumors.

Identification of a promoter that controls aromatase expression in human breast cancer and adipose stromal cells

Aromatase, a cytochrome P450, catalyzes three consecutive hydroxylation reactions converting C19 androgens to aromatic C18 estrogens. In this study, the regulatory properties of a 696-base pair region, that contains the promoter II and is situated immediately upstream of exon II of the human aromatase gene, were investigated. Chloramphenicol acetyltransferase (CAT) functional studies with DNA segments derived from this genomic region and primer-extension analysis revealed the presence of a second promoter which is functional in adipose stromal cells and in breast cancer cells. Detailed DNase-1 footprinting analysis, DNA mobility shift assays, and CAT functional studies of this genomic region were performed and led to the identification of a segment (B1) that could act as a promoter (probably promoter I.3) in adipose stromal and breast cancer cells. The study revealed further that the B1 region could be divided into two domains which were designated RE1 and RE2. RE1 was found to have the promoter activity, and RE2 was found to regulate the promoter activity of RE1, but in different manners in MCF-7 cells (as an example of breast cancer cells) and in adipose stromal cells. RE2 was found to function as a positive regulatory element in MCF-7 cells and as a negative regulatory element in adipose stromal cells, respectively. DNA mobility shift and UV-cross-linking experiments with BrUrd-substituted B1 fragment and nuclear extracts isolated from two types of cells were performed. The experiments identified DNA-bound proteins with molecular masses around 50 kDa. These findings serve as the basis for further examination of the regulatory mechanism of aromatase expression in human breast cancer and adipose stromal cells.

Estrone formation from dehydroepiandrosterone in cultured human breast adipose stromal cells

The metabolism of dehydroepiandrosterone (DHA) and androstenedione (A-dione) was studied in cultured human adipose stromal cells obtained from breast tissue of six premenopausal patients undergoing reduction mammoplasty. Cells were maintained in culture in the presence of 10% fetal bovine serum. Studies were carried out during the proliferative and confluent phases of culture with radiolabelled substrates (2 microCi, 10 nM). During the early phases of replication 7 alpha-hydroxydehydroepiandrosterone (7 alpha-OHDHA) was formed from DHA. As the cells reached confluence, the major metabolite of DHA in cells from all patients was A-dione indicating the presence of 3 beta-hydroxysteroid dehydrogenase/isomerase (3 beta-HSD). The conversion of DHA to A-dione was variable among patients when cells were confluent with 30-80% of substrate being metabolized to this product. Adipose stromal cells synthesized estrone (E1) from DHA once A-dione formation was established. Under basal conditions E1 was obtained in cells from three of the six patients examined with up to 36% substrate converted to this product. Dexamethasone (Dex 10(-7) M) stimulated E1 formation in cells from all subjects with up to 50% of substrate being converted. Parallel studies comparing the conversion of DHA with A-dione to E1 revealed that as the cells became confluent, E1 formation from both substrates was similar. The pattern of steroid metabolism was also examined in primary culture and in subculture. Passage 1 cells continued to form A-dione as a major metabolite of DHA, and did not revert to the pattern of metabolism found in primary cells during the early stages of replication, when 7 alpha-hydroxylation predominated. Human adipose stromal cells actively metabolize DHA, producing 7 alpha-OHDHA, A-dione and E1 as principal metabolites. Changes in the circulating levels of DHA may directly influence the formation of E1 in peripheral tissues. This source of E1 will be modulated by factors controlling 3 beta-HSD and aromatase activities.

Heterogeneity in adipose tissue metabolism: causes, implications and management of regional adiposity

The observation that different patterns of adipose tissue distribution are associated with different metabolic abnormalities, has recently given new impetus to research in obesity. Due to several methodologic problems, however, many aspects of regional excess of adipose tissue are still poorly understood. Among them, the causes and the metabolic consequences of regional adiposity are particularly important. Heterogeneity in adipose tissue distribution may be determined by a combination of genetic and hormonal causes. Both factors may determine differences in metabolism of various adipose tissue compartments primarily by regulating LPL production, storage and release of triacylglycerols, and aromatization of androgens. Furthermore, changes in adipocyte sensitivity to hormones such as, sex steroids, glucocorticoids, insulin and adrenergic hormones may also regulate fat distribution in various adipose tissue compartments. The metabolic heterogeneity of adipose tissue from various compartments, particularly the differences between the "portal" and subcutaneous adipose tissues, may account for several metabolic abnormalities associated with "upper body adiposity". However, no direct evidence is available to confirm this hypothesis. Recent advances in the methodology to study adipose tissue distribution (mainly CT and MRI) may provide the necessary tools to evaluate the true impact of adiposity in various compartments on intermediary metabolism and to identify a "morbid" adipose tissue compartment. These observations may help in designing better therapeutic strategies targeted towards regional adiposity and its metabolic complications.

The independent effects of polycystic ovary syndrome and obesity on serum concentrations of gonadotrophins and sex steroids in premenopausal women

OBJECTIVE

To investigate the basal levels of gonadotrophins and sex steroids, with special reference to the effects of obesity and body fat distribution, in premenopausal women, both those with polycystic ovary syndrome (PCOS) and those with normal ovaries and regular menstrual cycles.

DESIGN

Cross-sectional study. The separate effects of obesity (and body fat distribution and fasting insulin levels) and PCOS on endocrine variables were evaluated by means of analysis of covariance.

PATIENTS

Sixty-seven women with anovulatory menstrual cycles and polycystic ovaries according to ultrasonography and 59 women with normal ovaries and regular cycles, both groups covering a wide range of body mass index (BMI, PCOS, 17.6-37.4, mean 25.7 kg/m2; controls, 18.8-40.9, mean 25.1 kg/m2).

MEASUREMENTS

Serum levels of gonadotrophins, sex steroid hormones, prolactin and GH obtained in the early follicular phase in the controls, fasting insulin levels, anthropometric measures (BMI, skinfolds, waist hip ratio).

RESULTS

Mean serum concentrations of LH, androstenedione, testosterone, the free androgen index (FAI; all P < 0.0001) and DHEAS (P < 0.01) were higher, and serum FSH (P < 0.01) and serum SHBG levels lower (P < 0.0001), in the PCOS group than in the controls. Women with PCOS had a more pronounced upper body fat distribution and higher fasting insulin levels than the controls. Independent of PCOS, BMI was positively associated with serum levels of FSH (P < 0.001) and negatively with levels of LH (P < 0.05), LH/FSH ratio (P < 0.0001), SHBG (P < 0.0001) and androstenedione (P < 0.01), whereas for levels of testosterone, FAI and DHEAS the impact of obesity differed significantly between the groups. Thus, in the PCOS group, testosterone levels (P < 0.05) and the FAI (P < 0.001) were positively associated with BMI, whereas they were constant throughout the entire range of BMI in the controls. DHEAS levels were positively associated with BMI in the PCOS group (P < 0.05) and negatively in the controls (P < 0.01). Measures of upper body fat were related to testosterone and FAI levels, independent of BMI.

CONCLUSIONS

Lower FSH levels were found in women with PCOS than during the early follicular phase of normally ovulating women, suggesting a role in anovulation in PCOS. Obesity itself exerted effects on endocrine variables, with the net result of a reduced LH/FSH ratio and lower serum levels of androstenedione and SHBG in both groups; obesity was associated with increased levels of DHEAS, testosterone and FAI exclusively in the women with PCOS. The results underline the endocrine impact of obesity and body fat distribution and the necessity of applying reference values of BMI matched subjects when establishing the endocrine profile of women with PCOS.

Induction of aromatase gene expression in human placental choriocarcinoma (JAR) cells by phorbol esters

The expression of aromatase in JAR cells, human placental choriocarcinoma cells, was found to be induced by the treatment of phorbol 12,13-diacetate (PDA), phorbol 12,13-didecanoate (PDD), or phorbol 12-myristate 13-acetate (TPA), but not 4 alpha-phorbol, 12,13-didecanoate (4 alpha PDD). At 1 microM or higher concentrations, these phorbol esters increased the level of aromatase mRNA and aromatase activity in a dose- and time-dependent fashion. Since the rates of the decrease of aromatase mRNA in phorbol ester treated and untreated cells were not significantly different in the presence of actinomycin D, the induction was not due to an increase in the stability of aromatase mRNA, but rather due to an increase in the synthesis of aromatase mRNA. The stimulation was not inhibited by 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7). It is thought that the induction either follows a protein kinase C-independent manner or results from a down-regulation of protein kinase C pathway. Studies from several laboratories have revealed that the regulation of the expression of aromatase in estrogen-producing cells involves very complex processes. The apparent induction of aromatase expression in JAR cells by phorbol esters represent a mechanism modulating estrogen production in human placental choriocarcinoma cells, that may or may not be utilized in other estrogen-producing cells.

Effect of dexamethasone and cytochrome P450 inhibitors on the formation of 7 alpha-hydroxydehydroepiandrosterone by human adipose stromal cells

7 alpha-Hydroxydehydroepiandrosterone (7 alpha-OHDHA) is a major metabolite of dehydroepiandrosterone (DHA) using adipose stromal cells. To gain a better understanding of the factors regulating DHA metabolism, we examined the effect of dexamethasone and cytochrome P450 inhibitors on the formation of 7 alpha-OHDHA. Dexamethasone (10(-9) to 10(-7) M) stimulated 7 alpha-OHDHA formation in a dose-dependent manner with a 2- to 5-fold stimulation at 10(-7) M. The dexamethasone stimulated 7 alpha-OHDHA formation was inhibited by RU486 in a dose-dependent manner with suppression to basal levels at 10(-6) M. Progesterone (10(-7) M) had no effect on 7 alpha-OHDHA formation suggesting that the dexamethasone stimulation was acting through the glucocorticoid receptor. Conversion of DHA to 7 alpha-OHDHA was inhibited by ketoconazole and metyrapone. An inhibition of 70-80% was obtained with ketoconazole and 25-60% with metyrapone at concentrations of 10(-5) M. Aminoglutethimide phosphate was less effective than either ketoconazole or metyrapone in inhibiting 7 alpha-OHDHA formation with < 30% inhibition at 10(-5) M. These studies indicate that 7-hydroxylation provides an alternative pathway for the metabolism of DHA in peripheral tissues. This pathway, which is regulated by glucocorticoids, may influence the amount of DHA available for conversion to androstenedione and its subsequent aromatization to estrone. The biological role of the 7-oxygenated metabolites and their effects on other steroidogenic pathways have not been established.

Metabolism of dehydroepiandrosterone by cultured human adipose stromal cells: identification of 7 alpha-hydroxydehydroepiandrosterone as a major metabolite using high performance liquid chromatography and mass spectrometry

Studies of the metabolism of dehydroepiandrosterone (DHA) by cultured human adipose stromal cells revealed that the most abundant metabolite detected by HPLC was a polar compound accounting for up to 45% of total radioactivity. This metabolite was isolated by chromatography on Lipidex 5000 from the culture medium of breast adipose stromal cells cultured with unlabelled DHA (5 microM) and identified by combined capillary gas chromatography and mass spectrometry as 7 alpha-hydroxydehydroepiandrosterone (7 alpha-OHDHA). In breast adipose stromal cells, the conversion of DHA to 7 alpha-OHDHA was linear from a substrate concentration of 10 nM to 1 microM. At 1 microM substrate concentration, the formation of 7 alpha-OHDHA in four patients ranged from 6.1 to 22.5 ng/10(5) cells/24 h. Incubations carried out in primary culture and up to the fifth subculture revealed continued formation of 7 alpha-OHDHA. Adipose stromal cells from abdomen, flank and perinephric fat also produced 7 alpha-OHDHA from DHA. These studies have shown that 7 alpha-OHDHA is a major metabolite of DHA in human adipose stromal cells. The variability from patient to patient and the magnitude of this conversion suggests that this pathway may play an important role in the peripheral metabolism of DHA.

Aromatase gene is amplified in MCF-7 human breast cancer cells

The levels of the aromatase gene and its expression in MCF-7 human breast cancer cells and seven additional cultured cells were investigated. Using normal human foreskin fibroblasts as the control, the aromatase gene appeared to be amplified in MCF-7 cells as shown by Southern and DNA slot blot analyses utilizing human placental aromatase cDNA as the probe. However, the promoter I.1 and the first exon of the aromatase gene were not amplified in MCF-7 cells based on results obtained from DNA slot blot analysis using oligonucleotide probes having sequences derived from those regions of human aromatase gene. Aromatase was expressed at a very low level in this cell line as indicated by Northern blot analysis to measure the level of aromatase mRNA, immunoprecipitation analysis to measure the level of aromatase protein, and aromatase activity measurement. Furthermore, nucleotide sequence analysis of the aromatase cDNA obtained from MCF-7 cells by PCR techniques, revealed no sequence difference from that of the enzyme expressed in placenta. These results lead us to conclude that the expression of aromatase in MCF-7 cells is under the control of an unusual promoter and aromatase gene expression is repressed at the transcriptional level in these cells.

Influence of adipose tissue distribution on the biological activity of androgens

To establish whether the conversion of androstenedione (A) to estrogens and 5 alpha-reduced metabolites in human adipose tissue was determined by the site of origin of the tissue, studies were carried out on adipose stromal cells from different body sites. Adipose tissue was obtained from the breast, omentum, abdomen, lower thigh, upper thigh, buttock, and flank from patients undergoing liposuction for cosmetic reasons or at surgery. Stromal cells were isolated after incubation of the adipose tissue with collagenase and were grown in culture using alpha-minimal essential medium (MEM) + 15% fetal calf serum. Studies of A metabolism were carried out when the cells were between days 4 and 12 in culture. After an 8-hour incubation with (3H)-A as substrate, estrone (E1), testosterone (T), 5 alpha-androstanedione (5 alpha-A-dione), androsterone (AND), and dihydrotestosterone (DHT) were isolated using thin layer and paper chromatography. The conversion per 1 x 10(6) cells of A of E1 was more than 10-fold greater in the upper thigh, buttock, and flank than in the breast, lower thigh, abdomen, or omentum (0.13-3.0 vs 0.01-0.09%). The formation of 5 alpha-reduced androgens varied from 0.86-10% and was similar in tissue from different body sites. Cortisol (10(-7) M) stimulated E1 formation 3- to 10-fold in cells from all sites, whereas 5 alpha-reductase activity was either unchanged or increased moderately (up to twofold). In cells from the abdomen, omentum, and lower thigh, the formation of 5 alpha-reduced androgens was more than 10-fold greater than the formation of E1. In cells from the upper thigh, buttock, and flank, E1 formation was comparable to 5 alpha-reduced androgen formation. These studies show marked differences in the relative conversion of A to estrogens and 5 alpha-reduced androgens in adipose stromal cells depending on their site of origin, and they suggest that the distribution of body fat may be a major factor in determining the biologic effects of secreted androgens.

Aromatase activity in the breast and other peripheral tissues and its therapeutic regulation

Studies using [3H]androstenedione (A) demonstrated that this substrate can be aromatized to estrone (E1) in homogenates of breast carcinoma tissue and breast adipose tissue, in breast carcinoma and breast adipose stromal cells in culture, and in cultured adipose stromal cells from sites remote from the tumor. Using cultured breast carcinoma cells, it was shown that estrogen formation was stimulated by cortisol (10(-6) M) and inhibited by endogenous 5 alpha-reduced androgens: 5 alpha-androstene-dione greater than androsterone greater than dihydrotestosterone greater than epiandrosterone greater than 3 alpha- and 3 beta- androstanediol. It was also shown that 19-nortestosterone and 19-norandrostenedione (10(-6) M) inhibited E1 formation by 80%. Progesterone (10(-6) M) had no effect on aromatase activity, while the progestational agent R5020 (10(-6) M) caused a 70% inhibition. These studies emphasize that a variety of compounds can influence aromatase activity and that drugs which are used as aromatase inhibitors in patients with breast carcinoma may have multiple sites of action.