Concentrations of estrone, estradiol and their sulfates, and evaluation of sulfatase and aromatase activities in patients with breast fibroadenoma

Association of genetic polymorphisms with local steroid metabolism in human benign breasts

PURPOSE

Although alterations of concentrations in circulating steroids have been linked to single nucleotide polymorphisms (SNPs) of steroidogenic enzymes, we hypothesized that SNPs of such enzymes located within the breast affect local steroid concentrations more than products of such SNPs absorbed from the circulation.

METHODS

Steroids (estradiol, estrone, testosterone, androstenedione, DHEA, DHEA sulfate, progesterone) in nipple aspirate fluid (NAF) were purified by HPLC and they along with serum steroids were quantified by immunoassays. Polymorphisms of the transporter SLCO2B1 and enzymes HSD3B1, CYP19A1, HSD17B12, AKR1C3, CYP1B1, and SRD5A1 were measured in white blood cell DNA.

RESULTS

Steroid concentrations in NAF of subjects with homozygous minor genotypes differed from those with heterozygotes, i.e., SLCO2B1 (rs2851069) decreased DHEAS (p = 0.04), HSD17B12 (rs11555762) increased estradiol (p < 0.004), and CYP1B1 (rs1056836) decreased estradiol (p = 0.017) and increased progesterone (p = 0.05). Also, in serum, CYP19A1 (rs10046 and rs700518) both decreased testosterone (p = 0.02) and SRD5A1 increased androstenedione (p = 0.006). Steroids in subjects with major homozygotes did not differ from those with heterozygotes indicating recessive characteristics.

CONCLUSIONS

In the breast, SNPs were associated with decreased uptake of DHEAS (SLCO2B1), increased estradiol concentrations through increased oxidoreductase activity (HSD17B12), or decreased estradiol concentrations by presumed formation of 4-hydroxyestradiol (CYP1B1). CYP19A1 was associated with decreased testosterone concentrations in serum but had no significant effect on estrogen or androgen concentrations within the breast. The hormone differences observed in NAF were not usually evident in serum, indicating the importance of assessing the effect of these SNPs within the breast.

Breast fibroadenomas are less frequent in women with uterine fibroids

BACKGROUND

The etiology and incidence of Fibroadenoma (FA) as the most frequent benign breast mass and uterine fibroma (UF) as the most benign gynecological disorders are unknown.

OBJECTIVE

Considering the dependency of FA and UF to sex hormones, our objective was to investigate the association of these two neoplasms.

METHODS

Among women attending the hospital Gynecology Clinic, those with typical uterine fibroids in their pelvic ultrasound constituted cases and those with no pathology the controls. All participants underwent breast ultrasound for FA. Criteria for diagnosis of FA were a typical image for lumps <2 cm in women aged <40 and <1 cm in ages ≥ 40, and a histologic diagnosis for all other participants or larger lumps.

RESULTS

The mean age of cases and controls was 42.4 and 41.7 years, respectively. FA were detected in 140 (23%) of all participants; 19.7% of the cases, and 26.2% of the controls (p = 0.07). FA and UF had a borderline reverse association (OR = 0.69, 95% CI = 0.46-1.02, p = 0.07).

CONCLUSION

The incidence of FA is lower in patients with UF. Further studies are needed to find the selective effects of estrogen and progesterone on hormonal receptors of these two tumors.

Estrogen Sulfotransferase (SULT1E1): Its Molecular Regulation, Polymorphisms, and Clinical Perspectives

Estrogen sulfotransferase (SULT1E1) is a phase II enzyme that sulfates estrogens to inactivate them and regulate their homeostasis. This enzyme is also involved in the sulfation of thyroid hormones and several marketed medicines. Though the profound action of SULT1E1 in molecular/pathological biology has been extensively studied, its genetic variants and functional studies have been comparatively rarely studied. Genetic variants of this gene are associated with some diseases, especially sex-hormone-related cancers. Comprehending the role and polymorphisms of SULT1E1 is crucial to developing and integrating its clinical relevance; therefore, this study gathered and reviewed various literature studies to outline several aspects of the function, molecular regulation, and polymorphisms of SULT1E1.

Discovery of New Protein Targets of BPA Analogs and Derivatives Associated with Noncommunicable Diseases: A Virtual High-Throughput Screening

BACKGROUND

Bisphenol A analogs and derivatives (BPs) have emerged as new contaminants with little or no information about their toxicity. These have been found in numerous everyday products, from thermal paper receipts to plastic containers, and measured in human samples.

OBJECTIVES

The objectives of this research were to identify in silico new protein targets of BPs associated with seven noncommunicable diseases (NCDs), and to study their protein-ligand interactions using computer-aided tools.

METHODS

Fifty BPs were identified by a literature search and submitted to a virtual high-throughput screening (vHTS) with 328 proteins associated with NCDs. Protein-protein interactions between predicted targets were examined using STRING, and the protocol was validated in terms of binding site recognition and correlation between in silico affinities and in vitro data.

RESULTS

According to the vHTS, several BPs may target proteins associated with NCDs, some of them with stronger affinities than bisphenol A (BPA). The best affinity score (the highest in silico affinity absolute value) was obtained after docking 4,4'-bis(N-carbamoyl-4-methylbenzensulfonamide)diphenylmethane (BTUM) on estradiol 17-beta-dehydrogenase 1 (-13.7 kcal/mol). However, other molecules, such as bisphenol A bis(diphenyl phosphate) (BDP), bisphenol PH (BPPH), and Pergafast 201 also exhibited great affinities (top 10 affinity scores for each disease) with proteins related to NCDs.

DISCUSSION

Molecules such as BTUM, BDP, BPPH, and Pergafast 201 could be targeting key signaling pathways related to NCDs. These BPs should be prioritized for in vitro and in vivo toxicity testing and to further assess their possible role in the development of these diseases. https://doi.org/10.1289/EHP7466.

Acetaminophen Modulates the Expression of Steroidogenesis-Associated Genes and Estradiol Levels in Human Placental JEG-3 Cells

Acetaminophen is the only medication recommended for pain and fever management during pregnancy. However, studies have reported an association between in utero acetaminophen and neurocognitive disorders later in life. Additionally, acetaminophen has been shown to have endocrine disrupting properties altering hormones critical for normal fetal development. As the placenta is an endocrine organ that produces hormones for fetal development, any attempts to elucidate the mechanism underlying in utero acetaminophen and birth outcomes must also focus on the placenta. The present study set out to examine the effect of acetaminophen on mRNA expression, protein expression, and hormone synthesis in placental JEG-3 cells. The analysis focused on genes involved in steroidogenesis and acetaminophen metabolism as well those with known roles as nuclear receptors and transporters. The results highlight that at high concentrations, acetaminophen reduced the gene expression of aromatase (CYP19A1) and type 1 3β-hydroxysteroid dehydrogenase (HSD3B1), and increased the expression of 17β-hydroxysteroid dehydrogenase (HSD17B1). Additionally, acetaminophen at high concentrations also reduced the protein expression of aromatase (CYP19A1). These effects were accompanied by a significant dose-dependent decrease in estradiol secretion. Estradiol plays an important role in the development of reproductive organs and the brain of the developing fetus. This study highlights the potential for acetaminophen to interfere with hormone regulation during pregnancy and underscores the need for additional studies aimed at understanding the endocrine disruption activity of acetaminophen during fetal development.

Positive association between progestins and the evolution of multiple fibroadenomas in 72 women

OBJECTIVE

Multiple fibroadenomas (MFA) of the breast is a rare benign disease, thus its natural history is poorly understood. The aim of our study was to describe the radiological evolution of MFA and to evaluate the influence of different factors on this evolution.

METHODS

This was a longitudinal cohort study. All patients included had two clinical and radiological assessments (breast ultrasound (US) and/or MRI) at least 5 years apart.

RESULTS

Seventy-two women were followed for 7.6 ± 2.1 years. The radiological evolution showed a decrease or stability in the number of fibroadenomas (FA) in 26/44 cases on the MRI and in 38/64 cases on the US. There was a decrease of size in 35/44 cases on the MRI and in 53/64 cases on the US. An increase in the number of FAs was found in 18/44 cases in the MRI and 26/64 cases in the US with, for the majority, a decrease of size (19/26 by MRI and 16/18 by MRI). Older age at the first FA (P < 0.0001) and at the diagnosis of MFA (P < 0.0001), pregnancy (P = 0.003) and progestin use (P < 0.001), particularly lynestrenol (P < 0.0001), had a beneficial effect on the evolution of MFA.

CONCLUSION

This is the first longitudinal study describing women with MFA. The radiological evolution of MFA seamed favorable and similar to that expected for a single FA. We identified factors influencing the evolution of the disease, including progestin treatments such as lynestrenol, which could have a beneficial effect. Our cohort should be followed further in order to expand our knowledge of MFA, especially concerning the risk of breast cancer.

Steroid enzyme and receptor expression and regulations in breast tumor samples - A statistical evaluation of public data

In spite of the significant progress of estrogen-dependent breast cancer (BC) treatment, aromatase inhibitor resistance is a major problem limiting the clinical benefit of this frontier endocrine-therapy. The aim of this study was to determine the differential expression of steroid-converting enzymes between tumor and adjacent normal tissues, as well as their correlation in modulating intratumoral steroid-hormone levels in post-menopausal estrogen-dependent BC. RNA sequencing dataset (n = 1097) of The-Cancer-Genome-Atlas (Breast Invasive Carcinoma) retrieved through the data portal of Genomic Data Commons was used for differential expressions and expression correlation analyses by Mann-Whitney U and Spearman's rank test, respectively. The results showed significant up-regulation of 17β-HSD7 (2.50-fold, p < 0.0001) in BC, supporting its effect in sex-hormone control. Besides, suppression of 11β-HSD1 expression (-8.29-fold, p < 0.0001) and elevation of 11β-HSD2 expression (2.04-fold, p < 0.0001) provide a low glucocorticoid environment diminishing BC anti-proliferation. Furthermore, 3α-HSDs were down-regulated (-1.59-fold, p < 0.01; -8.18-fold, p < 0.0001; -33.96-fold, p < 0.0001; -31.85-fold, p < 0.0001 for type 1-4, respectively), while 5α-reductases were up-regulated (1.41-fold, p < 0.0001; 2.85-fold, p < 0.0001; 1.70-fold, p < 0.0001 for type 1-3, respectively) in BC, reducing cell proliferation suppressers 4-pregnenes, increasing cell proliferation stimulators 5α-pregnanes. Expression analysis indicates significant correlations between 11β-HSD1 with 3α-HSD4 (r = 0.605, p < 0.0001) and 3α-HSD3 (r = 0.537, p < 0.0001). Significant expression correlations between 3α-HSDs were also observed. Our results systematically present the regulation of steroid-converting enzymes and their roles in modulating the intratumoral steroid-hormone levels in BC with a vivid 3D-schema, supporting novel therapy targeting the reductive 17β-HSD7 and proposing a new combined therapy targeting 11β-HSD2 and 17β-HSD7.

Estrone-3-Sulfate Stimulates the Proliferation of T47D Breast Cancer Cells Stably Transfected With the Sodium-Dependent Organic Anion Transporter SOAT (SLC10A6)

Estrogens play a pivotal role in the development and proliferation of hormone-dependent breast cancer. Apart from free estrogens, which can directly activate the estrogen receptor (ER) of tumor cells, sulfo-conjugated steroids, which maintain high plasma concentrations even after menopause, first have to be imported into tumor cells by carrier-mediated uptake and then can be cleaved by the steroid sulfatase to finally activate ERs and cell proliferation. In the present study, expression of the sodium-dependent organic anion transporter SOAT was analyzed in breast cancer and its role for hormone-dependent proliferation of T47D breast cancer cells was elucidated. The SOAT protein was localized to the ductal epithelium of the mammary gland by immunohistochemistry. SOAT showed high expression in different pathologies of the breast with a clear ductal localization, including ductal hyperplasia, intraductal papilloma, and intraductal carcinoma. In a larger breast cancer cDNA array, SOAT mRNA expression was high in almost all adenocarcinoma specimen, but expression did not correlate with either the ER, progesterone receptor, or human epidermal growth factor receptor 2 status. Furthermore, SOAT expression did not correlate with tumor stage or grade, indicating widespread SOAT expression in breast cancer. To analyze the role of SOAT for breast cancer cell proliferation, T47D cells were stably transfected with SOAT and incubated under increasing concentrations of estrone-3-sulfate (E₁S) and estradiol at physiologically relevant concentrations. Cell proliferation was significantly increased by 10^-9 M estradiol as well as by E₁S with EC₅₀ of 2.2 nM. In contrast, T47D control cells showed 10-fold lower sensitivity to E₁S stimulation with EC₅₀ of 21.7 nM. The E₁S-stimulated proliferation of SOAT-T47D cells was blocked by the SOAT inhibitor 4-sulfooxymethylpyrene. In conclusion: The present study clearly demonstrates expression of SOAT in breast cancer tissue with ductal localization. SOAT inhibition can block the E₁S-stimulated proliferation of T47D breast cancer cells, demonstrating that SOAT is an interesting novel drug target from the group of E₁S uptake carriers for anti-proliferative breast cancer therapy.

Phenobarbital-induced phosphorylation converts nuclear receptor RORα from a repressor to an activator of the estrogen sulfotransferase gene Sult1e1 in mouse livers

The estrogen sulfotransferase SULT1E1 sulfates and inactivates estrogen, which is reactivated via desulfation by steroid sulfatase, thus regulating estrogen homeostasis. Phenobarbital (PB), a clinical sedative, activates Sult1e1 gene transcription in mouse livers. Here, the molecular mechanism by which the nuclear receptors CAR, which is targeted by PB, and RORα communicate through phosphorylation to regulate Sult1e1 activation has been studied. RORα, a basal activity repressor of the Sult1e1 promoter, becomes phosphorylated at serine 100 and converts to an activator of the Sult1e1 promoter in response to PB. CAR regulates both the RORα phosphorylation and conversion. Our findings suggest that PB signals CAR to communicate with RORα via serine 100 phosphorylation, converting RORα from transcription repressor to activator of the Sult1e1 gene and inducing SULT1E1 expression in mouse livers.

Nipple Aspirate Fluid Hormone Concentrations and Breast Cancer Risk

Prior reports identify higher serum concentrations of estrogens and androgens as risk factors for breast cancer, but steroids in nipple aspirate fluid (NAF) may be more related to risk. Incident breast cancer cases and mammography controls were recruited. Sex steroids were measured in NAF from the unaffected breasts of cases and one breast of controls. Menopausal status and menstrual cycle phase were determined. NAF steroids were purified by HPLC and quantified by immunoassays. Conditional logistic regression models were used to examine associations between NAF hormones and case-control status. NAF samples from 160 cases and 157 controls were evaluable for hormones. Except for progesterone and dehydroepiandrosterone (DHEA), the NAF and serum concentrations were not significantly correlated. NAF estradiol and estrone were not different between cases and controls. Higher NAF (but not serum) DHEA concentrations were associated with cases, particularly among estrogen receptor (ER)-positive cases (NAF odds ratio (OR) = 1.18, 95 % confidence interval (CI) 1.02, 1.36). NAF DHEA was highly correlated with NAF estradiol and estrone but not with androstenedione or testosterone. Higher progesterone concentrations in both NAF and serum were associated with a lower risk of ER-negative cancer (NAF OR = 0.69, 95 % CI 0.51, 0.92). However, this finding may be explained by case-control imbalance in the number of luteal phase subjects (2 cases and 19 controls). The significantly higher concentration of DHEA in NAF of cases and its correlation with NAF estradiol indicates a potentially important role of this steroid in breast cancer risk; however, the negative association of progesterone with risk is tentative.

Steroid derivatives as inhibitors of steroid sulfatase

Sulfated steroids function as a storage reservoir of biologically active steroid hormones. The sulfated steroids themselves are biologically inactive and only become active in vivo when they are converted into their desulfated (unconjugated) form by the enzyme steroid sulfatase (STS). Inhibitors of STS are considered to be potential therapeutics for the treatment of steroid-dependent cancers such as breast, prostate and endometrial cancer. The present review summarizes steroid derivatives as inhibitors of STS covering the literature from the early years of STS inhibitor development to October of 2012. A brief discussion of the function, structure and mechanism of STS and its role in estrogen receptor-positive (ER+) hormone-dependent breast cancer is also presented. This article is part of a Special Issue entitled "Synthesis and biological testing of steroid derivatives as inhibitors".

A new nonestrogenic steroidal inhibitor of 17β-hydroxysteroid dehydrogenase type I blocks the estrogen-dependent breast cancer tumor growth induced by estrone

17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1) converts estrone (E1) into estradiol (E2) and is expressed in many steroidogenic tissues and breast cancer cell lines. Because the potent estrogen E2 stimulates the growth and development of hormone-dependent diseases, inhibition of the final step of E2 synthesis is considered a promising strategy for the treatment of breast cancer. On the basis of our previous study identifying 16β-(m-carbamoylbenzyl)-E2 (CC-156) as a lead compound for the inhibition of 17β-HSD1, we conducted a number of structural modifications to reduce its undesired residual estrogenic activity. The steroid derivative PBRM [3-(2-bromoethyl)-16β-(m-carbamoylbenzyl)-17β-hydroxy-1,3,5(10)-estratriene] emerged as a potent inhibitor of 17β-HSD1 with an IC(50) value of 68 nmol/L for the transformation of E1 into E2. When tested in the estrogen-sensitive breast cancer cell line T-47D and in mice, PBRM showed no estrogenic activity in the range of concentrations tested. Furthermore, with the purpose of evaluating the bioavailability of PBRM and CC-156 injected subcutaneously (2.3 mg/kg), we measured their plasmatic concentrations as a function of time, calculated the area under the curve (AUC(0-12h)) and showed a significant improvement for PBRM (772 ng*h/mL) compared with CC-156 (445 ng*h/mL). We next tested the in vivo efficiency of PBRM on the T-47D xenograft tumor model in female ovariectomized athymic nude mice. After a treatment with PBRM, tumor sizes in mice stimulated with exogenous E1 were completely reduced at the control group level (without E1 treatment). As a conclusion, PBRM is a promising nonestrogenic inhibitor of 17β-HSD1 for the treatment of estrogen-dependent diseases such as breast cancer.

Differential role of organic anion-transporting polypeptides in estrone-3-sulphate uptake by breast epithelial cells and breast cancer cells

The purpose of this study was to investigate the differential expression and function of organic anion-transporting polypeptides (OATPs) in breast epithelial and breast cancer cells. Estrone-3-sulfate (E3S), a substrate for 7 of 11 OATPs, is a predominant source of tumor estrogen in postmenopausal, hormone-dependent patients with breast cancer. Overexpression of certain OATPs (e.g., OATP1A2) reported in breast tumor tissues compared with surrounding normal tissues could contribute toward two to three times higher tumoral E3S concentration. Little is known about expression and function of other OATP family members among breast epithelial and breast cancer cells. We therefore compared gene and protein expression of seven OATPs (OATP1A2, OATP1B1, OATP1B3, OATP1C1, OATP2B1, OATP3A1, and OATP4A1) in immortalized breast epithelial cells (MCF10A), hormone-dependent breast cancer cells (MCF7), and hormone-independent breast cancer cells (MDA/LCC6-435, MDA-MB-231, and MDA-MB-468) by quantitative polymerase chain reaction and immunoblotting, respectively. Expression of solute carrier superfamily encoding for OATPs (SLCO) 1A2, 1B1, 1B3, 2B1, and 3A1 is exclusive, similar, or significantly higher in cancer cells compared with MCF10A cells. Protein expression of OATPs is found to be either exclusive or higher in cancer cells compared with MCF10A cells. Specificity of OATP-mediated E3S uptake is observed only in cancer cells, with the highest total uptake in MCF7 cells. Transport kinetics of E3S uptake demonstrates transport efficiency that is 10 times greater in the MCF7 cells than in the hormone-independent cells. These data suggest that OATPs could be a novel therapeutic target for hormone-dependent breast cancers, particularly in postmenopausal patients, where the major source of tumor estrogen is E3S.

Breast ductal lavage for assessment of breast cancer biomarkers

Lavage of the ductal systems of the breast provides fluid (DLF) containing hormones and products of hormone actions that may represent more accurately the composition of the breast than samples collected from blood or urine. The present study was undertaken to assess the presence of potential cancer biomarkers, their variation among individuals at high risk for breast cancer, and differences associated with menopause and tamoxifen treatment. Seventy seven tamoxifen-eligible subjects with a 5-year breast cancer risk estimate (Gail > 1.6%)(N = 53) or recently diagnosed breast cancer (N = 24) were offered tamoxifen therapy; those not accepting tamoxifen were under observation only. After six months, all subjects underwent ductal lavage (DL) in an unaffected breast. Estradiol (E2), estrone sulfate, androstenedione, dehydroepiandrosterone (DHEA), DHEA sulfate, progesterone, cathepsin D and epidermal growth factor (EGF) were measured in DLF by immunoassays. Data were expressed as the mass of analyte per mg of protein in DLF and normalized by natural log transformation. With the exception of DHEA, none of the analytes measured were significantly lower in postmenopausal women than in premenopausal women. The mean log(e) concentration difference in estradiol was 10.9%. Tamoxifen treatment for 6 months did not result in a significantly greater concentration of E2 or in any of the other analytes in DLF of pre- or postmenopausal women. The between-duct variance of the concentration of free steroids within the same breast averaged 51% less than that between subjects, and was similar to that of non-diffusible proteins. The maintenance of estradiol concentrations in the breast after menopause demonstrates the importance of local biosynthesis. The fact that DLF E2 does not reflect the high serum concentrations of E2 during tamoxifen treatment indicates that breast concentrations of estradiol may be under feedback control. Unlike studies of low risk populations, progesterone concentrations were not significantly less in postmenopausal than in premenopausal women. The similarity in variance of free steroids and protein analytes between ducts of a breast indicates little transfer of steroids between lobules.

Sex steroid hormone levels in breast adipose tissue and serum in postmenopausal women

Elevated levels of circulating estrogens and androgens are linked to higher breast cancer risk among postmenopausal women; however, little is known about hormone levels within the breast. Hormone concentrations within the breast may not be reflected in the blood and are likely important contributors to breast carcinogenesis. We used a previously validated method to measure levels of estrone, estradiol, androstenedione, and testosterone in adipose tissue removed as part of breast excisions performed for cancer in 100 postmenopausal women (69 ER/PR +/+ and 31 ER/PR -/-) participating in a breast cancer case-control study. We also measured the same steroid hormones, as well as estrone sulfate, and sex hormone-binding globulin (SHBG) in serum from these patients and 100 controls matched on ages at blood collection and on menopause. Overall, concentrations of serum hormones did not vary significantly between controls and cases. However, women with ER-/PR- breast cancers had lower circulating levels of all measured sex steroid hormones and higher SHBG levels than women with ER+/PR+ breast cancers and controls. Similarly, hormone concentrations in breast adipose tissue were higher among women with ER+/PR+ compared to ER-/PR- breast cancer, although differences were only significant for testosterone. These data demonstrate that high sex steroid concentrations in both serum and adipose tissues are more strongly related to ER+/PR+ than ER-/PR- breast cancers. Measurement of sex hormones in serum and in the microenvironment may help in understanding the hormonal etiology of breast cancer, suggest methods for prevention, and have value in gauging treatment response and prognosis.

Disposition of hop prenylflavonoids in human breast tissue

Hop-derived products may contain xanthohumol (XN), isoxanthohumol (IX), and the potent phytoestrogen 8-prenylnaringenin (8-PN). To evaluate the potential health effects of these prenylflavonoids on breast tissue, their concentration, nature of metabolites, and biodistribution were assessed and compared with 17beta-estradiol (E(2)) exposure. In this dietary intervention study, women were randomly allocated to hop (n=11; 2.04 mg XN, 1.20 mg IX, and 0.1 mg 8-PN per supplement) or control (n=10). After a run-in of >or=4 days, three supplements were taken daily for 5 days preceding an aesthetic breast reduction. Blood and breast biopsies were analyzed using HPLC-ESI-MS/MS. Upon hop administration, XN and IX concentrations ranged between 0.72 and 17.65 nmol/L and 3.30 and 31.50 nmol/L, and between 0.26 and 5.14 pmol/g and 1.16 and 83.67 pmol/g in hydrolyzed serum and breast tissue, respectively. 8-PN however, was only detected in samples of moderate and strong 8-PN producers (0.43-7.06 nmol/L and 0.78-4.83 pmol/g). Phase I metabolism appeared to be minor (approximately 10%), whereas extensive glucuronidation was observed (> 90%). Total prenylflavonoids showed a breast adipose/glandular tissue distribution of 38/62 and their derived E(2)-equivalents were negligible compared with E(2) in adipose (384.6+/-118.8 fmol/g, p=0.009) and glandular (241.6+/-93.1 fmol/g, p<0.001) tissue, respectively. Consequently, low doses of prenylflavonoids are unlikely to elicit estrogenic responses in breast tissue.

Uptake transporter organic anion transporting polypeptide 1B3 contributes to the growth of estrogen-dependent breast cancer

Estrone-3-sulfate is one of the most abundant estrogen precursors in postmenopausal women. We previously showed that estrone-3-sulfate transporters are present in human breast cancer-derived MCF-7 cells (J. Pharmacol. Exp. Ther. 311 (2004) 1032-1037) and that inhibition of estrone-3-sulfate uptake resulted in the suppression of cell growth (Pharm. Res. 22 (2005) 1634-1641); therefore, estrone-3-sulfate transporter should be a novel target for therapy of hormone-dependent breast cancers. The purpose of the present study is to identify the transporter(s) responsible for the uptake of estrone-3-sulfate in breast cancer cells. We obtained two subclones of MCF-7 cells with different estrone-3-sulfate uptake activities and searched for differentially expressed transporter genes by means of DNA microarray analysis. Among several candidate transporters identified, OATP1B3 was further evaluated, since the uptake characteristics of estrone-3-sulfate by MCF-7 cells seemed consistent with the transport properties of OATP1B3. The contribution of OATP1B3 to estrone-3-sulfate uptake by MCF-7 cells was examined by the relative activity factor (RAF) method, and was calculated to amount to 6%. This result suggests that OATP1B3 is one of the transporters contributing to the supply of the estrogen precursor estrone-3-sulfate to estrogen-dependent breast cancer cells.

Immunolocalization of estrogen-producing and metabolizing enzymes in benign breast disease: comparison with normal breast and breast carcinoma

It is well known that estrogens play important roles in the cell proliferation of breast carcinoma. Benign breast disease (BBD) contains a wide spectrum of diseases, and some are considered an important risk factor for subsequent breast carcinoma development. However, the significance of estrogens in BBD has remained largely unknown. Therefore, in this study, we examined tissue concentrations of estrogens and immunolocalization of estrogen-producing/metabolizing enzymes in BBD, and compared these findings with those in the normal breast and ductal carcinoma in situ (DCIS). Tissue concentration of estradiol in BBD (n = 9) was significantly (3.4-fold) higher than normal breast (n = 9) and nearly the same (0.7-fold) as in DCIS (n = 9). Immunoreactivity of estrogen sulfotransferase in BBD was significantly lower (n = 82) than normal breast (n = 28) but was not significantly different from DCIS (n = 28). Aromatase and steroid sulfatase immunoreactivities tended to be higher (P = 0.07) in BBD than in normal breast, and 17β-hydroxysteroid dehydrogenase type 1 immunoreactivity was significantly higher in BBD than normal breast in the postmenopausal tissues. Immunoreactivity of estrogen and progesterone receptors was also significantly higher in BBD than normal breast. These results suggest that tissue concentration of estradiol is increased in BBD at a level similar to DCIS, which is considered mainly due to loss of estrogen sulfotransferase expression. Increased local estradiol concentration in BBD due to aberrant expression of estrogen-producing/metabolizing enzymes may play important roles in the accumulation of estradiol-mediated growth and/or subsequent development of breast carcinoma.

Fruit and vegetable intakes are associated with lower risk of breast fibroadenomas in Chinese women

Fibroadenomas are common benign breast conditions among women and account for approximately 50% of breast biopsies performed. Dietary factors are known to influence benign breast conditions in the aggregate, but little is known of their association specifically with fibroadenoma. Our objective in this study was to evaluate the association between dietary and other factors and fibroadenoma risk. A case-control study, nested in a randomized trial of breast self-examination (BSE) in Chinese textile workers in Shanghai, China, was conducted between 1989 and 2000. The study sample included 327 affected women and 1070 controls. Women were administered a FFQ and a questionnaire that elicited reproductive and gynecological history and other information. Odds ratios, as estimates of relative risks, were calculated using multivariate conditional logistic regression. Significant decreasing trends in risk of fibroadenoma were observed with intake of fruits and vegetables and with number of live births, and a reduced risk was also associated with natural menopause, oral contraceptive use, and moderate exercise (walking and gardening). Increased risk of fibroadenoma was associated with heavy physical activity in one's 20s, breast cancer in a first-degree relative, and a history of prior benign breast lumps; and significant increasing trends in risk were observed with numbers of BSE per year and years of education. In conclusion, a diet rich in fruits and vegetables and the use of oral contraceptives may reduce risk of fibroadenoma.

Specific estrogen sulfotransferase (SULT1E1) substrates and molecular imaging probe candidates

This work focuses on the development of specific substrates for estrogen sulfotransferase (SULT1E1) to produce molecular imaging probes for this enzyme. SULT1E1 is a key enzyme in estrogen homeostasis, playing a central role in the prevention and development of human disease. In vitro sulfation assays showed alkyl and aryl substitutions to a fused heterocyclic system modeled after beta-naphthol (betaN), based on compounds that interact with the estrogen receptor, rendered several molecules with enhanced specificity for SULT1E1 over SULT1A1*1, SULT1A1*2, SULT1A3, and SULT2A1. Several 6-hydroxy-2-arylbenzothiazoles tested demonstrated excellent affinity--V(max)/K(m) ratios-and specificity for SULT1E1. K(m) values ranged from 0.12-2.36 microM. A strong correlation was observed between polarity of the 4'-sustituent on the 2-aryl moiety (Hammett sigma(p)) and the log(V(max)/K(m)) (r = 0.964). Substrate sensitivity is influenced by the acidity of the 6-phenolic group demonstrated by correlating its (1)H NMR chemical shift (delta(OH)) with the log(V(max)/K(m)) (r = 0.963). Acidity is mediated by the electron withdrawing capacity of the 4'-substituent outlined by the correlation of the C-2 (13)C NMR chemical shift (delta(C2)) with the log(V(max)/K(m)) (r = 0.987). 2-[4-(Methylamino)phenyl]-6-hydroxybenzothiazole (2b) was radiolabeled with carbon-11 ((11)C-(2b)) and used in vivo for microPET scanning and tissue metabolite identification. High PET signal was paralleled with the presence of radiolabeled (11)C-(2b)-6-O-sulfate and the SULT1E1 protein detected by western blot. Because this and other members of this family presenting specificity for SULT1E1 can be labeled with carbon-11 or fluorine-18, in vivo assays of SULT1E1 functional activity are now feasible in humans.

Binary and ternary crystal structure analyses of a novel inhibitor with 17β-HSD type 1: a lead compound for breast cancer therapy

Oestradiol is a well-characterized sex hormone that stimulates breast cancer and other oestrogen-related diseases. 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) catalyses the last step in the synthesis of oestradiol and androstenediol in breast tumour tissue. The enzyme's high expression and activity after simultaneous blockade of oestrogen receptors and inhibition of aromatase in the tumour shows the necessity for its inhibition as a requirement for breast cancer therapy. In the present paper, we report structures of the binary and ternary complexes of 17β-HSD1 with a new inhibitor E2B {3-[3′,17′β-dihydroxyestra-1′,3′,5′(10′)-trien-16′β-methyl]benzamide}, and the enzyme inhibition by the later. The IC50 value for E2B was determined to be 42 nM in T47D cells. Multiple interactions between E2B and the enzyme include hydrogen bonds and hydrophobic interactions, as well as π–π interactions. A kinetic study demonstrated that E2B inhibits the enzyme's reduction forming oestradiol from oestrone, with a Ki of 0.9±0.15 nM. Such strong inhibition is in agreement with its extensive interaction with the enzyme, suggesting its potential as a lead compound for breast cancer therapy. In fact, this possibility is enhanced by its capacity for cell penetration similar to natural steroids. Such inhibitors that block oestrogen synthesis to suppress the sulfatase pathway producing oestradiol can be used in adjuvant therapies with oestrogen receptor blockade, opening a new orientation of breast cancer treatment.

Aromatase inhibitors in breast cancer

Estrogens play important roles in breast cancer development and progression. In postmenopausal women, traditional endocrine therapies such as tamoxifen have sought to inhibit estrogen action by targeting the estrogen receptor itself. However, newer treatments are evolving that target estrogen production in postmenopausal tissues through inhibition of the aromatase enzyme. Clinical data demonstrate that these aromatase inhibitors are superior to tamoxifen as adjuvant therapy for breast cancer and have now replaced tamoxifen as first line therapy in a number of treatment regimens for postmenopausal breast cancer patients.

Shikonin, an ingredient of Lithospermum erythrorhizon, down-regulates the expression of steroid sulfatase genes in breast cancer cells

Steroid sulfatase (STS) has an important role in regulating the biosynthesis of estrogen within breast tumors. We aimed to investigate whether shikonin, an ingredient of Lithospermum erythrorhizon, could modulate STS expression in breast cancer cells. By MTT assay, shikonin inhibited the cell proliferation of breast cancer cells MCF-7 and SK-BR-3. Moreover, by semi-quantitative/quantitative reverse transcription polymerase chain reaction and dual-luciferase reporter based bioluminescent measurements, the mRNA and enzymatic activity levels of STS were decreased after shikonin treatment. Concluding, shikonin could act as a selective estrogen enzyme modulator by down-regulating the STS expression.

Src supports UDP-glucuronosyltransferase-2B7 detoxification of catechol estrogens associated with breast cancer

Mammary gland-distributed and ER-bound UDP-glucuronosyltransferase (UGT)-2B7 metabolizes genotoxic catechol-estrogens (CE) associated with breast cancer initiation. Although UGT2B7 has 3 PKC- and 2 tyrosine kinase (TK)-sites, its inhibition by genistein, herbimycin-A and PP2 with parallel losses in phospho-tyrosine and phospho-Y438-2B7 content indicated it requires tyrosine phosphorylation, unlike required PKC phosphorylation of UGT1A isozymes. 2B7 mutants at PKC-sites had essentially normal activity, while its TK-sites mutants, Y236F- and Y438F-2B7, were essentially inactive. Overexpression of regular or active Src, but not dominant-negative Src, in 2B7-transfected COS-1 cells increased 2B7 activity and phospho-Y438-2B7 by 50%. Co-localization of 2B7 and regular SrcTK in COS-1 cells that was dissociated by pretreatment with Src-specific PP2-inhibitor provided strong evidence Src supports 2B7 activity. Consistent with these findings, evidence indicates an appropriate set of ER proteins with Src-homology binding-domains, including 2B7 and well-known multi-functional Src-engaged AKAP12 scaffold, supports Src-dependent phosphorylation of CE-metabolizing 2B7 enabling it to function as a tumor suppressor.

Measurement of sex steroid hormones in breast adipocytes: methods and implications

BACKGROUND

The lack of validated methods for measuring sex steroid hormones in breast tissue has limited our knowledge of their role in the development of breast cancer. We explored the feasibility of measuring hormones in breast adipocytes for epidemiologic and clinical studies by refining an existing assay procedure and assessing the reliability of hormone measurements using the modified assay. This report presents the reproducibility of measurements of androstenedione (A), testosterone (T), estrone (E(1)), and estradiol (E(2)), using breast adipose tissue samples obtained from women undergoing surgical resection for a variety of pathologic conditions.

METHODS

Breast adipose tissues were obtained from 20 women. Measurements of the steroid hormones were carried out by harvesting oil from adipocytes following enzymatic digestion of the adipose tissue, extracting and chromatographing the steroids, and quantifying them by RIA. The study was conducted in three phases: first, samples from five women were used to assess the assay procedure; following this, tissues from an additional five women were assayed repeatedly to determine reproducibility of the hormone measurements. Finally, using samples from 10 women undergoing surgical resection of a breast tumor, we evaluated hormone concentrations in samples distal and proximal to the tumor. The assay coefficient of variation and intraclass correlation coefficient were used to assess hormone reproducibility.

RESULTS

The within-batch coefficients of variation ranged from 5% to 17%, and between-batch estimates were between 2% and 10%, suggesting that E(1), E(2), A, and T can be reliably measured in breast adipocytes. Among samples obtained from women undergoing surgical resection of a breast tumor, hormone levels did not differ between adipose tissue fragments that were distal or proximal to the tumor, with the possible exception of E(1) in which levels were 10% higher in distal fragments.

CONCLUSION

These data support the feasibility of measuring steroid hormone concentrations in breast adipocytes in epidemiologic studies. Future investigations that include the measurement of hormones in the breast microenvironment may have value in understanding breast carcinogenesis, developing prevention strategies, and assessing hormonal treatments.

Glucocorticoid receptor expression in breast cancer associates with older patient age

Breast cancer can be classified according to estrogen (ER), progesterone (PR), and HER2 receptor expression. Recent evidence suggests that activation of the glucocorticoid receptor (GR) contributes to breast cell survival, although the incidence of GR expression in primary human breast tumors is not well established. We therefore evaluated ER, PR, HER2, and GR by immunohistochemistry from 231 patients and found that while African American (AA) patient tumors were much more likely to be ER negative compared to tumors from non-AA patients, GR expression was significantly higher in tumors from patients >or=50 regardless of ancestry. Prospective examination of GR expression in tumors should be considered to determine whether GR contributes to long-term clinical outcome.

Estrogen and progesterone receptor levels in nonneoplastic breast epithelium of breast cancer cases versus benign breast biopsy controls

BACKGROUND

Previous studies and biological mechanisms of carcinogenesis suggest that the steroid receptor content of benign breast epithelium may be related to breast cancer risk. The objective in this study was to compare the levels of estrogen receptor-alpha (ER) and progesterone receptor (PR) in nonneoplastic breast epithelium between breast cancer cases and biopsy controls.

METHODS

Between 1995 and 1997 at two sites (Women's College Hospital in Toronto and Kingston General Hospital), 667 women who were scheduled for diagnostic excisional breast biopsies completed a questionnaire providing personal information and agreed to allow analysis of routinely resected tissue. Histological slides with nonneoplastic epithelium were available for 101 cancer cases and 200 biopsy controls in Toronto and for 105 cancer cases and 119 controls in Kingston. Nonneoplastic epithelium was examined with immunohistochemical assays to determine the percent of epithelial cells staining for ER and PR. Unconditional logistic regression was used to calculate odds ratios (OR) stratified by study site.

RESULTS

The ER content of nonneoplastic tissue was higher in cases than biopsy controls in unadjusted analyses; after adjustment for age, however, a weak association remained in only one of the study sites. After adjustment for age, the PR content of nonneoplastic tissue was slightly lower in breast cancer cases than controls in one study site. Furthermore, this inverse association was confined to women with PR negative breast cancer in comparison to the controls. No interaction between ER and PR content of nonneoplastic tissue was observed in relation to the odds of having breast cancer.

CONCLUSION

The results of this study are consistent with only a slight indication of increased ER levels in nonneoplastic tissue in breast cancer cases relative to controls. This study contributes to the understanding of breast cancer by examining both ER and PR in nonneoplastic tissue. Limitations remain, however, such as the necessity of using as controls women with benign breast changes, difficulties in selecting the appropriate tissue for analysis, and tissue sampling concurrent to diagnosis.

Efficacy of estriol in inhibiting epithelial proliferation in mammary fibroadenoma: randomized clinical trial

CONTEXT AND OBJECTIVE

Mammary fibroadenoma is a disease that affects a large number of women of reproductive age. The aim of this study was to evaluate the proliferative activity of mammary fibroadenoma through expression of Ki-67 and c-myc antigens, following administration of oral contraceptive with or without estriol.

DESIGN AND SETTING

Placebo-controlled double-blind randomized clinical trial in the Mastology Sector of the Department of Gynecology, Universidade Federal de São Paulo.

METHODS

Thirty-three fibroadenoma patients were studied. Ten women (group 1) took an oral contraceptive constituted by levonorgestrel and ethinyl estradiol together with placebo manufactured in the same capsule for four consecutive cycles with a seven-day interval between them. The other 23 patients (group 2) took the same oral contraceptive together with estriol, which was put into the same capsule and used in the same way as among the group 1 patients. After four cycles, the nodules were surgically removed and sent for immunohistochemical analysis of Ki-67 and c-myc expression.

RESULTS

The Ki-67 and c-myc analysis did not reveal any significant differences between the study groups. The values were 9.16 and 10.54 for group 1 and 10.86 and 17.03 for group 2, respectively. There was a tendency towards higher expression of antigens in group 2.

CONCLUSION

Our results showed that there was no significant statistical difference in Ki-67 and c-myc expression between our study groups, but only a tendency towards higher expression among users of oral contraceptives containing estriol.

Hormonal markers in breast cancer: coexpression, relationship with pathologic characteristics, and risk factor associations in a population-based study

The objective of this study was to evaluate the coexpression patterns of hormonal markers in breast cancer tissue and their relationship with pathologic characteristics and epidemiologic risk factors. We evaluated the expression of 17 markers by immunohistochemistry in 842 invasive breast carcinomas collected in a population-based case-control study conducted in Poland. Based on marker correlations, factor analysis identified four major coexpression patterns (factors): "nuclear receptor factor" [estrogen receptor (ER)-alpha, progesterone receptor, androgen receptor, cyclin D1, and aromatase], "estrogen metabolism/ER-beta factor" (ER-beta, peroxisome proliferator-activated receptor-gamma, steroid sulfatase, estrogen sulfonotransferase, and cytochrome P450 1B1), "HER2 factor" (human epidermal growth factor receptor 2, E-cadherin, cyclooxygenase-2, aromatase, steroid sulfatase), and "proliferation factor" (cytokeratin 5, cytokeratin 5/6, epidermal growth factor receptor, P53). Three of these factors corresponded to molecular subtypes previously defined by expression profiling; however, the estrogen metabolism/ER-beta factor seemed to be distinctive. High scores for this factor were associated with high tumor grade (P heterogeneity = 0.02), younger age at menarche (P heterogeneity = 0.04), lower current body mass index among premenopausal women (P heterogeneity = 0.01), and older age at menopause (P heterogeneity = 0.04). High scores for the proliferation factor were also associated with early menarche (P heterogeneity < 0.0001), and in contrast to the estrogen metabolism/ER-beta factor, higher current body mass index among premenopausal women (P heterogeneity = 0.03). Our analysis of hormonal pathway markers independently confirmed several previously defined molecular subtypes identified by gene expression profiling and augmented these findings by suggesting the existence of additional relationships related to ER-beta and enzymes involved in hormone metabolism.

Effect of oral contraceptive with and without associated estriol on ultrasound measurements of breast fibroadenoma: randomized clinical trial

CONTEXT AND OBJECTIVE

Fibroadenomas are the most common benign tumors of the female breast. The aim of this study was to evaluate the proliferative activity of breast fibroadenoma as shown by ultrasound measurements, following administration of oral contraceptives with and without associated estriol.

DESIGN AND SETTING

This was a randomized, double-blind, placebo-controlled clinical trial carried out in the Mastology Sector, Department of Gynecology, Universidade Federal de São Paulo.

METHODS

We studied 33 women with fibroadenomas. Ten were placed in group 1 and took an oral contraceptive consisting of levonorgestrel and ethinyl estradiol together with placebo material in the same capsule, for four consecutive cycles with a seven-day interval between them. The other 23 patients constituted group 2 and took the oral contraceptive as above together with estriol in the same capsule, in the same way as done by the group 1 patients. We took ultrasound measurements of their tumors (in three dimensions) before and after the intake of medication. At the end of the study, all the patients had their tumors removed by surgery.

RESULTS

We observed decreased fibroadenoma width among the users of oral contraceptives with placebo, and this decrease was statistically significant. In the other group, we did not observe any changes (in width, length or height).

CONCLUSION

The results confirm that estriol may block the protective effect of oral contraceptives on fibroadenomas, since we observed decreased fibroadenoma width among the group 1 patients but not the group 2 patients.

Thiosemicarbazones of Formyl Benzoic Acids as Novel Potent Inhibitors of Estrone Sulfatase

Thiosemicarbazones of the microbial metabolite madurahydroxylactone, a polysubstituted benzo[a]naphthacenequinone, have been previously reported by us as potent nonsteroidal inhibitors of the enzyme estrone sulfatase (cyclohexylthiosemicarbazone 1, IC50 0.46 microM). The active pharmacophore of 1 has now been identified to be 2-formyl-6-hydroxybenzoic acid cyclohexylthiosemicarbazone (25, IC50 4.2 microM). The active partial structure was derivatized in the search for novel agents against hormone-dependent breast cancer. Further substantial increases in activity were achieved by reversal of functional groups leading to the cyclohexylthiosemicarbazones of 5-formylsalicylic acid (35, IC50 0.05 microM) and 3-formylsalicylic acid (34, IC50 0.15 microM) as the most potent analogues identified to date. Both compounds were shown to be noncompetitive inhibitors of estrone sulfatase with Ki values of 0.13 microM and 0.12 microM, respectively. The compounds showed low acute toxicity in the hen's fertile egg screening test.

Androgens and Estrogens in the Etiology and Prevention of Breast Cancer

Breast cancer is the most common cause of cancer death in women worldwide. Rates vary about fivefold around the world, but they are increasing in regions that until recently had low rates of disease. Despite the numerous uncertainties surrounding the etiology of breast cancer, intensive epidemiological, clinical, and genetic studies have identified a number of biologic and social traits as risk factors associated with breast cancer. Principal among them are the evidence of BRCA1 and BRCA2 susceptibility genes, familial history of breast cancer, age, higher socioeconomic status, ionizing radiation, tallness in adult life, alcohol consumption, and a variety of hormone and metabolic factors. Among the hormonal influences, a relevant etiological function has been ascribed to elevated levels of estrogens, their active metabolites, and androgens. These endocrine factors may represent future targets for breast cancer prevention.

Sonography of Palpable Breast Masses

Ultrasound use should be considered in most instances of a palpable breast finding, particularly in young women. A primary advantage is the ability to directly correlate the physical exam finding with imaging. Ultrasound is useful in characterizing palpable masses as well as detecting cancer in women with negative mammograms. The negative-predictive value of imaging for cancer in the evaluation of a palpable lump is very high, which may reassure women with low-suspicion palpable findings. Short-term follow-up of a palpable mass with benign features may be feasible, though further study is needed to establish criteria. A suspicious dominant palpable finding should be further evaluated even if imaging is negative.

Endogenous sex hormone levels and mammographic density among postmenopausal women

BACKGROUND

Mammographic density is one of the strongest predictors of breast cancer risk. The mechanism by which breast density increases breast cancer risk is unclear although it has been hypothesized that breast density reflects cumulative exposure to estrogens.

METHODS

To evaluate this hypothesis, we conducted a cross-sectional study among 520 postmenopausal women in the Nurses' Health Study that examined the relation between circulating sex hormones and mammographic density. Women were postmenopausal and not taking exogenous hormones at the time of blood collection and mammogram. Percent breast density was measured from digitized mammograms using a computer-assisted method. Circulating estrone, estradiol, androstenedione, testosterone, DHEA, DHEA sulfate, sex hormone-binding globulin, progesterone, and prolactin were measured in plasma.

RESULTS

In contrast to the prior hypothesis, circulating estrogens were inversely related to percent mammographic density. The mean percent mammographic density was 25.6% among women in the lowest quartile of circulating estradiol compared with 14.4% among women in the highest quartile [Spearman correlation (r) = -0.22, P < 0.0001]. Circulating estrogens alone explained 1% to 5% of the variation of mammographic density. Body mass index was positively associated with circulating estradiol levels (r = 0.45, P < 0.0001) and inversely related to percent mammographic density (r = -0.51, P < 0.0001). After adjustment for body mass index, there was no association between estradiol and breast density (r = 0.01, P = 0.81). Likewise, there was no relation between the other sex hormones measured or prolactin and mammographic density after adjustment for body mass index.

CONCLUSION

These findings indicate that in postmenopausal women, mammographic density is independent of circulating sex hormone levels.

Benign breast diseases

Benign breast diseases have always been neglected in comparison to cancer, despite the fact that there are many more patients with such diseases than patients presenting to a breast clinic for cancer. Like normal breast tissues, benign breast diseases are under a complex system of controls by both systemic hormonal and local factors. In this review, we attempt to present an overview of the latest knowledge concerning the epidemiology, classification, clinical presentation, management, and physiopathology of these disorders.

Sulfotransferase 2A1 forms estradiol-17-sulfate and celecoxib switches the dominant product from estradiol-3-sulfate to estradiol-17-sulfate

Using recombinant sulfotransferases (SULTs) expressed in E. coli, beta-estradiol (E2) sulfonation was examined to determine which SULT enzyme is responsible for producing E2-17-sulfate (E2-17-S). SULTs 1A1*1, 1A1*2, 1A3, 1E1 and 2A1 all sulfated E2 to varying extents. No activity was observed with SULT1B1. Among the SULTs studied, SULT2A1 produced primarily E2-3-sulfate (E2-3-S), but also some E2-17-S and trace amounts of E2 disulfate. SULT2A1 had a K(m) value of 1.52 microM for formation of E2-3-S and 2.95 microM for formation of E2-17-S. SULT2A1 had the highest V(max) of 493 pmol/min/mg protein for formation of E2-3-S, which was 8.8- and 47-fold higher than the maximal rates of formation of E2-17-S and E2 disulfate, respectively. SULT2A1 formed E2-3-S more efficiently. However, when celecoxib (0-160 microM) was included in the incubation with either SULT2A1 or human liver cytosol, sulfonation switched from E2-3-S to E2-17-S in a concentration-dependent manner. The ratio of E2-17-S/E2-3-S went up to 15 with SULT2A1, and was saturated at 1 with human liver cytosol. In both cases, more E2-17-S was formed, with the unreacted E2 remained unchanged, suggesting celecoxib probably bound to a separate effector site to cause a conformational change in SULT2A1, which favored production of E2-17-S. The ability of celecoxib to alter the position of sulfonation of E2 may in part explain its success in the experimental prevention and treatment of breast cancer.

Comparison of hormone levels in nipple aspirate fluid of pre- and postmenopausal women: effect of oral contraceptives and hormone replacement

The effects of ovarian suppression by oral contraceptives as well as hormone replacement therapy were studied on hormone levels and on products of hormone action in nipple aspirate fluid (NAF) from breasts of pre- and postmenopausal women. Multiple samples per subject revealed high consistency (intraclass correlation coefficients) for all products measured. Compared with premenopausal women, NAF progesterone was much lower in postmenopausal women, but NAF androstenedione, dehydroepiandrosterone, and dehydroepiandrosterone sulfate concentrations were not different. With oral contraceptive use, estradiol, estrone sulfate, and progesterone levels were similarly lower in serum and NAF. In postmenopausal women, NAF estradiol and estrone sulfate were not significantly less than those in premenopausal women, nor were epidermal growth factor or cathepsin D levels, but IL-6 was elevated. Despite corresponding changes in hormones in serum and NAF over time, correlations based on simultaneous sampling were not significant. It is concluded that: 1) potential precursors of estradiol remain at comparable levels in the breast after menopause; 2) local synthesis is important for maintenance of estradiol levels in NAF of postmenopausal women but less important for progesterone; and 3) changes in the serum parameters are accurately reflected in NAF, but only after a matter of days. These findings provide additional validation for the physiological relevance of NAF hormone levels as potential breast cancer risk markers.

Recent insight on the control of enzymes involved in estrogen formation and transformation in human breast cancer

The great majority of breast cancers are in their early stage hormone-dependent and it is well accepted that estradiol (E2) plays an important role in the genesis and evolution of this tumor. Human breast cancer tissues contain all the enzymes: estrone sulfatase, 17beta-hydroxysteroid dehydrogenase, aromatase involved in the last steps of E2 bioformation. Sulfotransferases which convert estrogens into the biologically inactive estrogen sulfates are also present in this tissue. Quantitative data show that the 'sulfatase pathway', which transforms estrogen sulfates into the bioactive unconjugated E2, is 100-500 times higher than the 'aromatase pathway', which converts androgens into estrogens. The treatment of breast cancer patients with anti-aromatases is largely developed with very positive results. However, the formation of E2 via the 'sulfatase pathway' is very important in the breast cancer tissue. In recent years it was found that antiestrogens (e.g. tamoxifen, 4-hydroxytamoxifen), various progestins (e.g. promegestone, nomegestrol acetate, medrogestone, dydrogesterone, norelgestromin), tibolone and its metabolites, as well as other steroidal (e.g. sulfamates) and non-steroidal compounds, are potent sulfatase inhibitors. In another series of studies, it was found that E2 itself has a strong anti-sulfatase action. This paradoxical effect of E2 adds a new biological response of this hormone and could be related to estrogen replacement therapy in which it was observed to have either no effect or to decrease breast cancer mortality in postmenopausal women. Interesting information is that high expression of steroid sulfatase mRNA predicts a poor prognosis in patients with +ER. These progestins, as well as tibolone, can also block the conversion of estrone to estradiol by the inhibition of the 17beta-hydroxysteroid dehydrogenase type I (17beta-HSD-1). High expressison of 17beta-HSD-1 can be an indicator of adverse prognosis in ER-positive patients. It was shown that nomegestrol acetate, medrogestone, promegestone or tibolone, could stimulate the sulfotransferase activity for the local production of estrogen sulfates. This is an important point in the physiopathology of this disease, as it is well known that estrogen sulfates are biologically inactive. A possible correlation between this stimulatory effect on sulfotransferase activity and breast cancer cell proliferation is presented. In agreement with all this information, we have proposed the concept of selective estrogen enzyme modulators (SEEM). In conclusion, the blockage in the formation of estradiol via sulfatase, or the stimulatory effect on sulfotransferase activity in combination with anti-aromatases can open interesting and new possibilities in clinical applications in breast cancer.

Effect of nomegestrol acetate on estrogen biosynthesis and transformation in MCF-7 and T47-D breast cancer cells

Although ovaries serve as the primary source of estrogen for pre-menopausal women, after menopause estrogen biosynthesis from circulating precursors occurs in peripheral tissues by the action of several enzymes, 17beta-hydroxysteroid dehydrogenase 1 (17beta-HSD1), aromatase and estrogen sulfatase. In the breast, both normal and tumoral tissues have been shown to be capable of synthesizing estrogens, and this local estrogen production can be implicated in the development of breast tumors. In these tissues, estradiol (E(2)) can be synthesized by three pathways: (1) estrone sulfatase transforms estrogen sulfates into bioactive estrogens, (2) 17beta-HSD1 converts estrone (E(1)) into E(2), (3) aromatase which converts androgens into estrogens is also present and contributes to the in situ synthesis of active estrogens but to a far lesser extent than estrone sulfatase. Quantitative assessment of E(2) formation in human breast tumors indicates that metabolism of estrone sulfate (E(1)S) via the sulfatase pathway produces 100-500 times more E(2) than androgen aromatization. Breast tissue also possesses the estrogen sulfotransferase involved in the conversion of estrogens into their sulfates that are biologically inactive. In the present review, we summarized the action of the 19-nor-progestin nomegestrol acetate (NOMAC) on the sulfatase, 17beta-HSD1 and sulfotransferase activities in the hormone-dependent MCF-7 and T47-D human breast cancer cell lines. Using physiological doses of substrates NOMAC blocks very significantly the conversion of E(1)S to E(2). It inhibits the transformation of E(1) to E(2). NOMAC has a stimulatory effect on sulfotransferase activity in both cell lines, with a strong stimulating effect at low doses but only a weak effect at high concentrations. The effects on the three enzymes are always stronger in the progesterone-receptor rich T47-D cell line as compared with the MCF-7 cell line. Besides, no effect is found for NOMAC on the transformation of androstenedione to E(1) in the aromatase-rich choriocarcinoma cell line JEG-3. In conclusion, the inhibitory effect provoked by NOMAC on the enzymes involved in the biosynthesis of E(2) (sulfatase and 17HSD pathways) in estrogen-dependent breast cancer, as well as the stimulatory effect on the formation of the inactive E(1)S, can open attractive perspectives for future clinical trials.

Involvement of Estrone-3-Sulfate Transporters in Proliferation of Hormone-Dependent Breast Cancer Cells

Although circulating estrone-3-sulfate is a major precursor of biologically active estrogen, permeation across the plasma membrane is unlikely to occur by diffusion because of the high hydrophilicity of the molecule. The object of this study was to clarify the involvement of specific transporter(s) in the supply of estrone-3-sulfate to human breast cancer-derived T-47D cells, which grow in an estrogen-dependent manner. The proliferation of T-47D cells was increased by the addition of estrone-3-sulfate, or estradiol, to the cultivation medium. The initial uptake rate of estrone-3-sulfate kinetically exhibited a single saturable component, with Km and Vmax values of 7.6 microM and 172 pmol/mg of protein/min, respectively. The replacement of extracellular Na+ with Li+, K+, or N-methylglucamine+ had no effect on the uptake of [3H]estrone-3-sulfate. The uptake was strongly inhibited by sulfate conjugates of steroid hormones, but not by estradiol-17beta-glucuronide. Taurocholate and sulfobromophthalein inhibited the uptake, whereas other tested anionic and cationic compounds did not. The expression of organic anion transporting polypeptides, OATP-D and OATP-E, which are candidate transporters of estrone-3-sulfate, was detected by reverse transcription-polymerase chain reaction analysis, although their actual involvement in the uptake of estrogen remains to be clarified. In conclusion, the uptake of estrone-3-sulfate by T-47D cells was mediated by a carrier-mediated transport mechanism, suggesting that the estrogen precursor is actively imported by estrogen-dependent breast cancer cells.

Differential effects of progestins on breast tissue enzymes

There is substantial evidence that mammary cancer tissue contains all the enzymes responsible for the local biosynthesis of estradiol (E2) from circulating precursors. Two principal pathways are implicated in the final steps of E2 formation in breast cancer tissue: the 'aromatase pathway' that transforms androgens into estrogens and the 'sulfatase pathway' that converts estrone sulfate (E1S) into estrone (E1) via estrone sulfatase. The final step is the conversion of weak E1 to potent biologically active E2 via reductive 17beta-hydroxysteroid dehydrogenase type 1 activity. It is also well established that steroid sulfotransferases, which convert estrogens into their sulfates, are present in breast cancer tissues. One of the possible means of blocking E2 effects in breast cancer is to use anti-estrogens, which act by binding to the estrogen receptor (ER). Another option is to block E2 using anti-enzymes (anti-sulfatase, anti-aromatase, or anti-17beta-hydroxysteroid dehydrogenase (17beta-HSD). Various progestins (e.g. promegestone, nomegestrol acetate, medrogestone, 17-deacetyl norgestimate, dydrogesterone and its 20-dihydro derivative), as well as tibolone and its metabolites, have been shown to inhibit estrone sulfatase and 17beta-hydroxysteroid dehydrogenase. Some progestins and tibolone can also stimulate sulfotransferase activity. These various progestins may therefore provide a new option for the treatment of breast cancer.

Variation in Estradiol, Estradiol Precursors, and Estrogen-related Products in Nipple Aspirate Fluid from Normal Premenopausal Women

The purpose of the study was to measure the concentrations of estradiol, its primary precursors, and factors with which it interacts in the breast, and determine their sources of variation. Nipple aspirate fluid (NAF) was collected from premenopausal women during the mid-luteal phase of the menstrual cycle. The fluid was diluted and unconjugated steroids were extracted. Estradiol was further purified by a solvent partition into aqueous NaOH. Androgens were measured in the non-phenolic fraction. Water-soluble, conjugated steroids and proteins were measured in the aqueous residue. All analytes were measured by immunoassays. Permutation methods were used to determine the correlations over multiple periods of time. The average concentration of estradiol in NAF was 435 pmol/L after purification but was many times higher when assayed without purification. Estrone and dehydroepiandrosterone (DHEA) sulfates were present in 3.7 and 75 μmol/L concentrations, respectively, while unconjugated androstenedione and DHEA were present in nanomole per liter concentrations. Lack of the steroid sulfates in NAF in 19% of subjects had no effect on NAF estradiol levels but was associated with a 77% lower concentration of unconjugated DHEA. Progesterone was present in concentrations that were 3- to 4-fold higher than normal serum concentrations (mean: 291 nmol/L). Cathepsin D, epidermal growth factor, and interleukin 6 had average values of 3.4 μg/mL, 424 ng/mL, and 1.7 ng/mL, respectively. Correlations between breasts were between 0.57 and 0.84 for the several analytes; correlations over time ranged from 0.64 and 0.93 with estrone sulfate highest in both categories. The lower correlation between breasts than within breasts indicates that local factors play an important role in determining the levels of many of these analytes in the breast. The high stability of the concentrations of several analytes over time indicates that fluctuations in environmental factors have little immediate effect on levels in the breast, and portends their utility as surrogate breast cancer risk markers.

The selective estrogen enzyme modulators in breast cancer: a review

It is well established that increased exposure to estradiol (E(2)) is an important risk factor for the genesis and evolution of breast tumors, most of which (approximately 95-97%) in their early stage are estrogen-sensitive. However, two thirds of breast cancers occur during the postmenopausal period when the ovaries have ceased to be functional. Despite the low levels of circulating estrogens, the tissular concentrations of these hormones are significantly higher than those found in the plasma or in the area of the breast considered as normal tissue, suggesting a specific tumoral biosynthesis and accumulation of these hormones. Several factors could be implicated in this process, including higher uptake of steroids from plasma and local formation of the potent E(2) by the breast cancer tissue itself. This information extends the concept of 'intracrinology' where a hormone can have its biological response in the same organ where it is produced. There is substantial information that mammary cancer tissue contains all the enzymes responsible for the local biosynthesis of E(2) from circulating precursors. Two principal pathways are implicated in the last steps of E(2) formation in breast cancer tissues: the 'aromatase pathway' which transforms androgens into estrogens, and the 'sulfatase pathway' which converts estrone sulfate (E(1)S) into E(1) by the estrone-sulfatase. The final step of steroidogenesis is the conversion of the weak E(1) to the potent biologically active E(2) by the action of a reductive 17beta-hydroxysteroid dehydrogenase type 1 activity (17beta-HSD-1). Quantitative evaluation indicates that in human breast tumor E(1)S 'via sulfatase' is a much more likely precursor for E(2) than is androgens 'via aromatase'. Human breast cancer tissue contains all the enzymes (estrone sulfatase, 17beta-hydroxysteroid dehydrogenase, aromatase) involved in the last steps of E(2) biosynthesis. This tissue also contains sulfotransferase for the formation of the biologically inactive estrogen sulfates. In recent years, it was demonstrated that various progestins (promegestone, nomegestrol acetate, medrogestone, dydrogesterone, norelgestromin), tibolone and its metabolites, as well as other steroidal (e.g. sulfamates) and non-steroidal compounds, are potent sulfatase inhibitors. Various progestins can also block 17beta-hydroxysteroid dehydrogenase activities. In other studies, it was shown that medrogestone, nomegestrol acetate, promegestone or tibolone can stimulate the sulfotransferase activity for the local production of estrogen sulfates. All these data, in addition to numerous agents which can block the aromatase action, lead to the new concept of 'Selective Estrogen Enzyme Modulators' (SEEM) which can largely apply to breast cancer tissue. The exploration of various progestins and other active agents in trials with breast cancer patients, showing an inhibitory effect on sulfatase and 17beta-hydroxysteroid dehydrogenase, or a stimulatory effect on sulfotransferase and consequently on the levels of tissular levels of E(2), will provide a new possibility in the treatment of this disease.

Estrogen-metabolizing gene polymorphisms in the assessment of breast carcinoma risk and fibroadenoma risk in Caucasian women

BACKGROUND

Genes encoding enzymes involved in estrogen metabolism are held to be candidate genes for associations with breast disease. In these candidate genes, no critical combination of single-nucleotide polymorphisms (SNPs) for assessing breast carcinoma risk has been reported to date.

METHODS

In a large case-control study, the authors investigated 10 estrogen-metabolizing SNPs in 396 patients with breast carcinoma, 154 patients with fibroadenoma, and 1936 healthy control patients without breast carcinoma in their personal history. The following 10 SNPs were analyzed using sequencing-on-chip technology via a solid-phase polymerase chain reaction assay performed on oligonucleotide microarrays: catechol-O-methyltransferase Val158Met G-->A, 17-beta-hydroxysteroid dehydrogenase type 1 vIV A-->C, cytochrome P-450 (CYP) family 17 A2 allele T-->C, CYP1A1-1 MspI restriction fragment length polymorphism (RFLP) T-->C, CYP1A1-2 Ile462Val A-->G, CYP19-1 Trp39Arg T-->C, CYP19-2 Arg264Cys C-->T, CYP19-3 Cys1558Thr C-->T, steroid-5-alpha reductase type 2 Val89Leu G-->C, and vitamin D receptor BsmI RFLP. A total of 21,350 genotypes were evaluated. Associations and two-way interaction models were calculated using stepwise logistic regression.

RESULTS

In a multiple model, CYP1A1-1 (P = 0.004) and CYP1A1-2 (P = 0.03) were found to be associated with significantly decreased and increased risks of breast carcinoma, respectively. When two-way interactions involving investigated SNPs were ascertained, no significant interactions among polymorphisms were noted. Comparison of patients with fibroadenoma with control patients revealed significantly increased and decreased risks of fibroadenoma when the mutant alleles of CYP17 (P = 0.02) and CYP1A1-1 (P = 0.04), respectively, were present.

CONCLUSIONS

The authors obtained the first SNP data indicating that CYP17 and CYP1A1-1 play a role in the pathogenesis of fibroadenoma. Although the authors were not able to develop interaction models involving SNPs, they did provide evidence that CYP1A1 is a low-penetrance susceptibility gene with respect to breast carcinoma in a large series of Caucasian women.