New development in intracrinology of breast carcinoma

Obesity-Associated Breast Cancer: Analysis of Risk Factors and Current Clinical Evaluation

Several studies show that a significantly stronger association is obvious between increased body mass index (BMI) and higher breast cancer incidence. Additionally, obese and postmenopausal women are at higher risk of all-cause and breast cancer-specific mortality compared with non-obese women with breast cancer. In this context, increased levels of estrogens, excessive aromatization activity of the adipose tissue, overexpression of pro-inflammatory cytokines, insulin resistance, adipocyte-derived adipokines, hypercholesterolemia, and excessive oxidative stress contribute to the development of breast cancer in obese women. Genetic evaluation is an integral part of diagnosis and treatment for patients with breast cancer. Despite trimodality therapy, the four-year cumulative incidence of regional recurrence is significantly higher. Axillary lymph nodes as well as primary lesions have diagnostic, prognostic, and therapeutic significance for the management of breast cancer. In clinical setting, because of the obese population primary lesions and enlarged lymph nodes could be less palpable, the diagnosis may be challenging due to misinterpretation of physical findings. Thereby, a nomogram has been created as the "Breast Imaging Reporting and Data System" (BI-RADS) to increase agreement and decision-making consistency between mammography and ultrasonography (USG) experts. Additionally, the "breast density classification system," "artificial intelligence risk scores," ligand-targeted receptor probes," "digital breast tomosynthesis," "diffusion-weighted imaging," "18F-fluoro-2-deoxy-D-glucose positron emission tomography," and "dynamic contrast-enhanced magnetic resonance imaging (MRI)" are important techniques for the earlier detection of breast cancers and to reduce false-positive results. A high concordance between estrogen receptor (ER) and progesterone receptor (PR) status evaluated in preoperative percutaneous core needle biopsy and surgical specimens is demonstrated. Breast cancer surgery has become increasingly conservative; however, mastectomy may be combined with any axillary procedures, such as sentinel lymph node biopsy (SLNB) and/or axillary lymph node dissection whenever is required. As a rule, SLNB-guided axillary dissection in breast cancer patients who have clinically axillary lymph node-positive to node-negative conversion following neoadjuvant chemotherapy is recommended, because lymphedema is the most debilitating complication after any axillary surgery. There is no clear consensus on the optimal treatment of occult breast cancer, which is much discussed today. Similarly, the current trend in metastatic breast cancer is that the main palliative treatment option is systemic therapy.

Obesity-Senescence-Breast Cancer: Clinical Presentation of a Common Unfortunate Cycle

There are few convincing studies establishing the relationship between endogenous factors that cause obesity, cellular aging, and telomere shortening. Without a functional telomerase, a cell undergoing cell division has progressive telomere shortening. While obesity influences health and longevity as well as telomere dynamics, cellular senescence is one of the major drivers of the aging process and of age-related disorders. Oxidative stress induces telomere shortening, while decreasing telomerase activity. When progressive shortening of telomere length reaches a critical point, it triggers cell cycle arrest leading to senescence or apoptotic cell death. Telomerase activity cannot be detected in normal breast tissue. By contrast, maintenance of telomere length as a function of human telomerase is crucial for the survival of breast cancer cells and invasion. Approximately three-quarters of breast cancers in the general population are hormone-dependent and overexpression of estrogen receptors is crucial for their continued growth. In obesity, increasing leptin levels enhance aromatase messenger ribonucleic acid (mRNA) expression, aromatase content, and its enzymatic activity on breast cancer cells, simultaneously activating telomerase in a dose-dependent manner. Meanwhile, applied anti-estrogen therapy increases serum leptin levels and thus enhances leptin resistance in obese postmenopausal breast cancer patients. Many studies revealed that shorter telomeres of postmenopausal breast cancer have higher local recurrence rates and higher tumor grade. In this review, interlinked molecular mechanisms are looked over between the telomere length, lipotoxicity/glycolipotoxicity, and cellular senescence in the context of estrogen receptor alpha-positive (ERα+) postmenopausal breast cancers in obese women. Furthermore, the effect of the potential drugs, which are used for direct inhibition of telomerase and the inhibition of human telomerase reverse transcriptase (hTERT) or human telomerase RNA promoters as well as approved adjuvant endocrine therapies, the selective estrogen receptor modulator and selective estrogen receptor down-regulators are discussed.

Human cytosolic steroid sulfotransferases: Versatile and rapid activity assays

Conjugation of steroids and sterol compounds with a sulfonate group is a major pathway in the regulation of their activity, synthesis and excretion. Three human cytosolic sulfotransferases are highly involved in the sulfonation of sterol compounds. SULT1E1 has a low nM affinity for estrogen sulfonation and also conjugates non-aromatic steroids with a significantly lower affinity. SULT2A1 is responsible for the high levels of fetal and adult dehydroepiandrosterone (DHEA) sulfate synthesis in the adrenal gland as well as many 3α and 3ß-hydroxysteroids and bile acids. SULT2B1b is responsible for the majority of cholesterol sulfation in tissues as well as conjugating 3ß-hydroxysteroids. Although there are multiple methods for assaying cytosolic SULT activity, two relatively simple, rapid and versatile assays for steroid sulfonation are described. The first method utilizes radiolabeled substrates and organic solvent extraction to isolate the radiolabeled product from the aqueous phase. The second assay utilizes 35S-3'-phosphoadenosine 5'-phosphosulfate (PAPS) to generate 35S-conjugated products that are resolved by thin layer chromatography. Both assays useful in situations requiring measurement of SULT activity in a timely manner.

The Role of Cow's Milk Consumption in Breast Cancer Initiation and Progression

PURPOSE OF REVIEW

This review evaluates cow milk's impact on breast carcinogenesis by linking recent epidemiological evidence and new insights into the molecular signaling of milk and its constituents in breast cancer (BCa) pathogenesis.

RECENT FINDINGS

Recent prospective cohort studies support the association between cow's milk consumption and the risk of estrogen receptor-α-positive (ER+) BCa. Milk is a complex biological fluid that increases systemic insulin-like growth factor 1 (IGF-1), insulin and estrogen signaling, and interacting hormonal promoters of BCa. Further potential oncogenic components of commercial milk include exosomal microRNAs (miR-148a-3p, miR-21-5p), bovine meat and milk factors, aflatoxin M1, bisphenol A, pesticides, and micro- and nanoplastics. Individuals with BRCA1 loss-of-function mutations and FTO and IGF1 gain-of-function polymorphisms enhancing IGF-1/mTORC1 signaling may be at increased risk for milk-induced ER+ BCa. Recent prospective epidemiological and pathobiochemical studies identify commercial milk consumption as a critical risk factor of ER+ BCa. Large meta-analyses gathering individuals of different ethnic origins with milk derived from dairy cows of varying genetic backgrounds and diverse feeding procedures as well as missing data on thermal processing of milk (pasteurization versus ultra-heat treatment) make multi-national meta-analyses unsuitable for BCa risk estimations in susceptible populations. Future studies are required that consider all vulnerable periods of breast carcinogenesis to cow's milk exposure, beginning during the perinatal period and puberty, since these are the most critical periods of mammary gland morphogenesis. Notwithstanding the need for better studies including detailed information on milk processing and vulnerable periods of human breast carcinogenesis, the available evidence suggests that dietary guidelines on milk consumption may have to be reconsidered.

Light on Shedding: A Review of Sex and Menstrual Cycle Differences in the Physiological Effects of Light in Humans

The human circadian system responds to light as low as 30 photopic lux. Furthermore, recent evidence shows that there are huge individual differences in light sensitivity, which may help to explain why some people are more susceptible to sleep and circadian disruption than others. The biological mechanisms underlying the differences in light sensitivity remain largely unknown. A key variable of interest in understanding these individual differences in light sensitivity is biological sex. It is possible that in humans, males and females differ in their sensitivity to light, but the evidence is inconclusive. This is in part due to the historic exclusion of women in biomedical research. Hormonal fluctuations across the menstrual cycle in women has often been cited as a confound by researchers. Attitudes, however, are changing with funding and publication agencies advocating for more inclusive research frameworks and mandating that women and minorities participate in scientific research studies. In this article, we distill the existing knowledge regarding the relationship between light and the menstrual cycle. There is some evidence of a relationship between light and the menstrual cycle, but the nature of this relationship seems dependent on the timing of the light source (sunlight, moonlight, and electric light at night). Light sensitivity may be influenced by biological sex and menstrual phase but there might not be any effect at all. To better understand the relationship between light, the circadian system, and the menstrual cycle, future research needs to be designed thoughtfully, conducted rigorously, and reported transparently.

Role of dietary fat on obesity-related postmenopausal breast cancer: insights from mouse models and methodological considerations

The increasing incidence rate of breast cancer in the last few decades is known to be linked to the upward trend of obesity prevalence worldwide. The consumption of high-fat diet in particular has been correlated with postmenopausal breast cancer risk. The underlying mechanisms, using suitable and reliable experimental mouse model, however, is lacking. The current review aims to discuss the evidence available from mouse models on the effects of dietary fats intake on postmenopausal breast cancer. We will further discuss the biochemical mechanisms involved in the occurrence of postmenopausal breast cancer. In addition, the methodological considerations and their limitations in obesity-related postmenopausal breast cancer, such as choice of mouse models and breast cancer cell lines as well as the study duration will be reviewed. The current review will provide a platform for further development of new xenograft models which may offer the opportunity to investigate the mechanisms of postmenopausal breast cancer in a greater detail.

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.

New cholic acid analogs: synthesis and 17β-hydroxydehydrogenase (17β-HSD) inhibition activity

The 17β-hydroxysteroid dehydrogenase (17β-HSD) enzyme family is involved in the biosynthesis of active steroids and its inhibition constitutes an interesting approach for treating estrogen-, androgen-dependent cancers and osteoporosis. In this study, a new series of cholic acid analogs was designed with the goal of improving the biological activity as 17β-HSD1 and 17β-HSD2 inhibitors. To this end, 23-cholyl amides 4–7, 3-O-p-toluenesulfonyl-23-cholyl amides 10–12, 23-cholyl-carbohydrazide 14, carbothioamide analog 15, and 23-cholyl-acylhydrazone derivatives 18–22 were synthesized from cholic acid (3) via coupling, sulfonation and substitution reactions. Basic treatment of keto group of 5 with p-bromoaniline afforded 8, meanwhile acidic treatment of 3 with thiosemicarbazide furnished the 23-cholyl-thiadiazole derivative 16. The synthesized compounds were evaluated for their inhibition activity against 17β-HSD1 and 17β-HSD2, and were found inactive at 1.0 μm concentration (inhibition <10%). However, the steroids 12, 21 and 22 showed inhibition of 21.1, 23.9 and 21.3%, respectively, against 17β-HSD2 at the same concentration. Therefore, these steroidal analogs can be further structurally modified to optimize their inhibition activity against 17β-HSD2 for the development of potential therapeutics.

HSD17B1 expression induces inflammation-aided rupture of mammary gland myoepithelium

Hydroxysteroid (17-beta) dehydrogenase type 1 (HSD17B1) converts low-active estrogen estrone to highly active estradiol. Estradiol is necessary for normal postpubertal mammary gland development; however, elevated estradiol levels increase mammary tumorigenesis. To investigate the significance of the human HSD17B1 enzyme in the mammary gland, transgenic mice universally overexpressing human HSD17B1 were used (HSD17B1TG mice). Mammary glands obtained from HSD17B1TG females at different ages were investigated for morphology and histology, and HSD17B1 activity and estrogen receptor activation in mammary gland tissue were assessed. To study the significance of HSD17B1 enzyme expression locally in mammary gland tissue, HSD17B1-expressing mammary epithelium was transplanted into cleared mammary fat pads of wild-type females, and the effects on mammary gland estradiol production, epithelial cells and the myoepithelium were investigated. HSD17B1TG females showed increased estrone to estradiol conversion and estrogen-response element-driven estrogen receptor signaling in mammary gland tissue, and they showed extensive lobuloalveolar development that was further enhanced by age along with an increase in serum prolactin concentrations. At old age, HSD17B1TG females developed mammary cancers. Mammary-restricted HSD17B1 expression induced lesions at the sites of ducts and alveoli, accompanied by peri- and intraductal inflammation and disruption of the myoepithelial cell layer. The lesions were shown to be estrogen dependent, as treatment with an antiestrogen, ICI 182,780, starting when lesions were already established reversed the phenotype. These data elucidate the ability of human HSD17B1 to enhance estrogen action in the mammary gland in vivo and indicate that HSD17B1 is a factor inducing phenotypic alterations associated with mammary tumorigenesis.

Estrogen and androgen-converting enzymes 17β-hydroxysteroid dehydrogenase and their involvement in cancer: with a special focus on 17β-hydroxysteroid dehydrogenase type 1, 2, and breast cancer

Sex steroid hormones such as estrogens and androgens are involved in the development and differentiation of the breast tissue. The activity and concentration of sex steroids is determined by the availability from the circulation, and on local conversion. This conversion is primarily mediated by aromatase, steroid sulfatase, and 17β-hydroxysteroid dehydrogenases. In postmenopausal women, this is the primary source of estrogens in the breast. Up to 70-80% of all breast cancers express the estrogen receptor-α, responsible for promoting the growth of the tissue. Further, 60-80% express the androgen receptor, which has been shown to have tissue protective effects in estrogen receptor positive breast cancer, and a more ambiguous response in estrogen receptor negative breast cancers. In this review, we summarize the function and clinical relevance in cancer for 17β-hydroxysteroid dehydrogenases 1, which facilitates the reduction of estrone to estradiol, dehydroepiandrosterone to androstendiol and dihydrotestosterone to 3α- and 3β-diol as well as 17β-hydroxysteroid dehydrogenases 2 which mediates the oxidation of estradiol to estrone, testosterone to androstenedione and androstendiol to dehydroepiandrosterone. The expression of 17β-hydroxysteroid dehydrogenases 1 and 2 alone and in combination has been shown to predict patient outcome, and inhibition of 17β-hydroxysteroid dehydrogenases 1 has been proposed to be a prime candidate for inhibition in patients who develop aromatase inhibitor resistance or in combination with aromatase inhibitors as a first line treatment. Here we review the status of inhibitors against 17β-hydroxysteroid dehydrogenases 1. In addition, we review the involvement of 17β-hydroxysteroid dehydrogenases 4, 5, 7, and 14 in breast cancer.

CYP19A1 gene polymorphism and colorectal cancer etiology in Saudi population: case-control study

BACKGROUND

Considerable interest is directed toward the enzyme aromatase (CYP19A1) and the development of cancer, due to CYP19A1's role in estrogen biosynthesis. Several cancers display excessive intra-tumor accumulation of estrogens, and aromatase inhibitors are used for treatment. The CYP19A1 gene exhibits polymorphism and mutations that can alter its expression or aromatase activity and influence estrogen production. We designed this study to investigate the link between CYP19A1 polymorphism and susceptibility to colorectal cancer (CRC) development in Saudis.

PATIENTS AND METHODS

Blood samples from 100 CRC patients and 100 healthy controls were drawn for DNA extractions. Three polymorphic sites, rs4774585, rs936308, and rs4775936, were genotyped using Taqman genotyping by real-time polymerase chain reaction. Allelic and genotype frequencies were calculated and compared in the two groups.

RESULTS

All single nucleotide polymorphisms (SNPs) were polymorphic in Saudis, and comparison of allele frequencies showed several differences when compared to other populations. None of the SNPs were associated with the risk of CRC development in Saudis (P>0.05). Some gender and location (colon or rectal) differences were observed.

DISCUSSION

The results of this study highlighted the genetic heterogeneity existing between populations in the prevalence of different SNPs and their relation to disease state. It showed that, although rs4774585, rs936308, and rs4775936 are involved in CRC development in several populations, their role is not significant in the etiology of CRC in Saudis; however, some SNPs do increase susceptibility or resistance to CRC development as judged from the odds ratio. Further large-scale studies are warranted to clarify the role of the CYP19A1 development in CRC.

Modulation of estrogen synthesis and metabolism by phytoestrogens in vitro and the implications for women's health

Phytoestrogens are increasingly used as dietary supplements due to their suggested health promoting properties, but also by women for breast enhancement and relief of menopausal symptoms. Generally, phytoestrogens are considered to exert estrogenic activity via estrogen receptors (ERs), but they may also affect estrogen synthesis and metabolism locally in breast, endometrial and ovarian tissues. Considering that accurate regulation of local hormone levels is crucial for normal physiology, it is not surprising that interference with hormonal synthesis and metabolism is associated with a wide variety of women's health problems, varying from altered menstrual cycle to hormone-dependent cancers. Yet, studies on phytoestrogens have mainly focused on ER-mediated effects of soy-derived phytoestrogens, with less attention paid to steroid synthesis and metabolism or other phytoestrogens. This review aims to evaluate the potential of phytoestrogens to modulate local estrogen levels and the implications for women's health. For that, an overview is provided of the effects of commonly used phytoestrogens, i.e. 8-prenylnaringenin, biochanin A, daidzein, genistein, naringenin, resveratrol and quercetin, on estrogen synthesizing and metabolizing enzymes in vitro. The potential implications for women's health are assessed by comparing the in vitro effect concentrations with blood concentrations that can be found after intake of these phytoestrogens. Based on this evaluation, it can be concluded that high-dose supplements with phytoestrogens might affect breast and endometrial health or fertility in women via the modulation of steroid hormone levels. However, more data regarding the tissue levels of phytoestrogens and effect data from dedicated, tissue-specific assays are needed for a better understanding of potential risks. At least until more certainty regarding the safety has been established, especially young women would better avoid using supplements containing high doses of phytoestrogens.

What is known about melatonin, chemotherapy and altered gene expression in breast cancer

Melatonin, synthesized in and released from the pineal gland, has been demonstrated by multiple in vivo and in vitro studies to have an oncostatic role in hormone-dependent tumors. Furthermore, several clinical trials point to melatonin as a promising adjuvant molecule to be considered for cancer treatment. In the past few years, evidence of a broader spectrum of action of melatonin as an antitumor agent has arisen; thus, melatonin appears to also have therapeutic effects in several types of hormone-independent cancer, including ovarian, leukemic, pancreatic, gastric and non-small cell lung carcinoma. In the present study, the latest findings regarding melatonin molecular actions when concomitantly administered with either radiotherapy or chemotherapy in cancer were reviewed, with a particular focus on hormone-dependent breast cancer. Finally, the present study discusses which direction should be followed in the next years to definitely clarify whether or not melatonin administration could protect against non-desirable effects (such as altered gene expression and post-translational protein modifications) caused by chemotherapy or radiotherapy treatments. As treatments move towards personalized medicine, comparative gene expression profiling with and without melatonin may be a powerful tool to better understand the antitumor effects of melatonin, the pineal gland hormone.

Aromatase expression in atypical ductal hyperplasia in women

PURPOSE

To determine the levels of aromatase in atypical ductal hyperplasia (ADH) lesions, tissue surrounding the ADH, and in dense and non-dense normal breast tissue. We postulated that excess aromatase in breast tissue might, through production of increased estrogen, drive the carcinogenic process. Estrogens and their metabolites are thought to contribute to the development of breast cancer through estrogen receptor-mediated mechanisms and genotoxic effects of estrogen metabolites. ADH is a benign lesion of the breast which is associated with substantially increased risk for subsequent development of breast cancer. After 25 years, approximately 30% of women with ADH develop breast cancer. In women with three or more separate ADH lesions at the same time, 47% will develop breast cancer over that time period. Another important risk factor for breast cancer is the presence of mammographically dense breast tissue.

METHODS

We utilized quantitative immunochemical analysis of aromatase in biopsy tissue to test this possibility. Previously published results comparing dense with non-dense breast tissue in normal women (Vachon et al. Breast Cancer Res Treat 125:243-252, 2011) were used for comparisons with ADH. A well-characterized histochemical H-score was employed for quantitative assessment of aromatase in the various tissue studied.

RESULTS

The H-score of aromatase staining was statistically significantly higher (p = 0.003) in the ADH epithelium than surrounding epithelial tissue. In order of H-score from highest to lowest were ADH, issue surrounding ADH, dense normal and non-dense normal breast tissues. The levels of aromatase in a subset of women with ADH who went on to develop breast cancer were not higher than in women who did not.

CONCLUSIONS

We suggest from these studies that overexpression of aromatase in breast tissue and its resultant increase in estradiol levels may contribute to the later development of breast cancer in women with ADH.

Obesity-associated Breast Cancer: Analysis of risk factors

Several studies show that a significantly stronger association is obvious between increased body mass index (BMI) and higher breast cancer incidence. Furthermore, obese women are at higher risk of all-cause and breast cancer specific mortality when compared to non-obese women with breast cancer. In this context, increased levels of estrogens due to excessive aromatization activity of the adipose tissue, overexpression of pro-inflammatory cytokines, insulin resistance, hyperactivation of insulin-like growth factors (IGFs) pathways, adipocyte-derived adipokines, hypercholesterolemia and excessive oxidative stress contribute to the development of breast cancer in obese women. While higher breast cancer risk with hormone replacement therapy is particularly evident among lean women, in postmenopausal women who are not taking exogenous hormones, general obesity is a significant predictor for breast cancer. Moreover, increased plasma cholesterol leads to accelerated tumor formation and exacerbates their aggressiveness. In contrast to postmenopausal women, premenopausal women with high BMI are inversely associated with breast cancer risk. Nevertheless, life-style of women for breast cancer risk is regulated by avoiding the overweight and a high-fat diet. Estrogen-plus-progestin hormone therapy users for more than 5 years have elevated risks of both invasive ductal and lobular breast cancer. Additionally, these cases are more commonly node-positive and have a higher cancer-related mortality. Collectively, in this chapter, the impacts of obesity-related estrogen, cholesterol, saturated fatty acid, leptin and adiponectin concentrations, aromatase activity, leptin and insulin resistance on breast cancer patients are evaluated. Obesity-related prognostic factors of breast cancer also are discussed at molecular basis.

Progesterone induces progesterone receptor gene (PGR) expression via rapid activation of protein kinase pathways required for cooperative estrogen receptor alpha (ER) and progesterone receptor (PR) genomic action at ER/PR target genes

Progesterone Receptors (PRs) are critical effectors of estrogen receptor (ER) signaling required for mammary gland development and reproductive proficiency. In breast and reproductive tract malignancies, PR expression is a clinical prognostic marker of ER action. While estrogens primarily regulate PR expression, other factors likely contribute to a dynamic range of receptor expression across diverse tissues. In this study, we identified estrogen-independent but progestin (R5020)-dependent regulation of ER target genes including PGR in ER+/PR+ cancer cell lines. R5020 (10nM-10μM range) induced dose-dependent PR mRNA and protein expression in the absence of estrogen but required both PR and ERα. Antagonists of either PR (RU486, onapristone) or ERα (ICI 182,780) attenuated R5020 induction of TFF1, CTSD, and PGR. Chromatin immunoprecipitation (ChIP) assays performed on ER+/PR+ cells demonstrated that both ERα and PR were recruited to the same ERE/Sp1 site-containing region of the PGR proximal promoter in response to high dose progestin (10μM). Recruitment of ERα and PR to chromatin and subsequent PR mRNA induction were dependent upon rapid activation of MAPK/ERK and AKT; inhibition of these kinase pathways via U0126 or LY294002 blocked these events. Overall, we have identified a novel mechanism of ERα activation initiated by rapid PR-dependent kinase pathway activation and associated with phosphorylation of ERα Ser118 for estrogen-independent but progestin-dependent ER/PR cross talk. These studies may provide insight into mechanisms of persistent ER-target gene expression during periods of hormone (i.e. estrogen) ablation and suggest caution following prolonged treatment with aromatase or CYP17 inhibitors (i.e. contexts when progesterone levels may be abnormally elevated).

Promoter Methylation Status of Breast Cancer Susceptibility Gene 1 and 17 Beta Hydroxysteroid Dehydrogenase Type 1 Gene in Sporadic Breast Cancer Patients

Epigenetic modifications are involved in breast carcinogenesis. Identifying genes that are epigenetically silenced via methylation could select target patients for diagnostic as well as therapeutic potential. We assessed promoter methylation of breast cancer susceptibility gene 1 (BRCA1) and 17 Beta Hydroxysteroid Dehydrogenase Type 1 (17βHSD-1) in normal and cancer breast tissues of forty sporadic breast cancer (BC) cases using restriction enzyme based methylation-specific PCR (REMS-PCR). In cancerous tissues, BRCA1 and 17βHSD-1 were methylated in 42.5% and 97.5%, respectively, while normal tissues had 35% and 95% methylation, respectively. BRCA1 methylation in normal tissues was 12.2-fold more likely to associate with methylation in cancer tissues (p < 0.001). It correlated significantly with increased age at menopause, mitosis, the negative status of Her2, and the molecular subtype "luminal A" (p = 0.048, p = 0.042, p = 0.007, and p = 0.049, resp.). Methylation of BRCA1 and 17βHSD-1 related to luminal A subtype of breast cancer. Since a small proportion of normal breast epithelial cells had BRCA1 methylation, our preliminary findings suggest that methylation of BRCA1 may be involved in breast tumors initiation and progression; therefore, it could be used as a biomarker for the early detection of sporadic breast cancer. Methylation of 17βHSD-1 in normal and cancer tissue could save patients the long term use of adjuvant antiestrogen therapies.

Intratumoral estrogen production and actions in luminal A type invasive lobular and ductal carcinomas

The great majority of invasive lobular carcinoma (ILC) is estrogen-dependent luminal A type carcinoma but the details of estrogen actions and its intratumoral metabolism have not been well studied compared to invasive ductal carcinoma (IDC). We first immunolocalized estrogen-related enzymes including estrogen sulfotransferase (EST), estrogen sulfatase (STS), 17β-hydroxysteroid dehydrogenase (HSD) 1/2, and aromatase. We then evaluated the tissue concentrations of estrogens in ILC and IDC and subsequently estrogen-responsive gene profiles in these tumors in order to explore the possible differences and/or similarity of intratumoral estrogen environment of these two breast cancer subtypes. The status of STS and 17βHSD1 was significantly lower in ILCs than IDCs (p = 0.022 and p < 0.0001), but that of EST and 17βHSD2 vice versa (p < 0.0001 and p = 0.0106). In ILCs, tissue concentrations of estrone and estradiol were lower than those in IDCs (p = 0.0709 and 0.069). In addition, the great majority of estrogen response genes tended to be lower in ILCs. Among those genes above, FOXP1 was significantly higher in ILCs than in IDCs (p = 0.002). FOXP1 expression was reported to be significantly higher in relapse-free IDC patients treated with tamoxifen. Therefore, tamoxifen may be considered an option of endocrine therapy for luminal A type ILC patients. This is the first study to demonstrate the detailed and comprehensive status of intratumoral production and metabolism of estrogens and the status of estrogen response genes in luminal A-like ILC with comparison to those in luminal A-like IDCs.

Transcript level of AKR1C3 is down-regulated in gastric cancer

Steroid hormones have been shown to play a role in gastric carcinogenesis. Large amounts of steroid hormones are locally produced in the peripheral tissues of both genders. Type 5 of 17β-hydroxysteroid dehydrogenase, encoded by the AKR1C3 gene, plays a pivotal role in both androgen and estrogen metabolism, and its expression was found to be deregulated in different cancers. In this study we measured AKR1C3 transcript and protein levels in nontumoral and primary tumoral gastric tissues, and evaluated their association with some clinicopathological features of gastric cancer (GC). We found decreased levels of AKR1C3 transcript (p < 0.0001) and protein (p = 0.0021) in GC tissues compared with the adjacent, apparently histopathologically normal, mucosa. Lower levels of AKR1C3 transcript were observed in diffuse and intestinal types of GC, whereas AKR1C3 protein levels were decreased in tumors with multisite localization, in diffuse histological type, T3, T4, and G3 grades. We also determined the effect of the histone deacetylase inhibitor sodium butyrate (NaBu) on AKR1C3 expression in EPG 85-257 and HGC-27 GC cell lines. We found that NaBu elevates the levels of both AKR1C3 transcript and protein in the cell lines we investigated. Together, our results suggest that decreased expression of AKR1C3 may be involved in development of GC and can be restored by NaBu.

Intratumoral estrogen sulfotransferase induction contributes to the anti-breast cancer effects of the dithiocarbamate derivative TM208

AIM

Sulfotransferase-catalyzed sulfation is the most important pathway for inactivating estrogens. Thus, activation of estrogen sulfotransferase (EST) may be an alternative approach for the treatment of estrogen-dependent breast cancer. In this study we investigated the involvement of EST in anti-breast cancer effects of the dithiocarbamate derivative TM208 in vitro and in vivo.

METHODS

The viability of human breast cancer MCF-7 cells was determined using a SBB assay. Nude mice bearing MCF-7 cells were orally administered TM208 (50 and 150 mg·kg(-1)·d(-1)) for 18 days. The xenograft tumors and uteri were collected. The mRNA expression of EST was examined with real-time PCR. EST protein was detected with Western blot, ELISA or immunohistochemical staining assays. A radioactive assay was used to measure the EST activity. Uterotropic bioassay was used to examine the uterine estrogen responses.

RESULTS

Treatment with TM208 (10, 15 and 20 μmol/L) concentration-dependently increased EST expression in MCF-7 cells in vitro. Co-treatment with triclosan, an inhibitor of sulfonation, abolished TM208-induced cytotoxicity in MCF-7 cells. TM208 exhibited an apparent anti-estrogenic property: it exerted more potent cytotoxicity in E2-treated MCF-7 cells. In the nude mice bearing MCF-7 cells, TM208 administration time-dependently increased the expression and activity of EST, and blocked the gradual increase of E2 concentration in the xenograft tumors. Furthermore, TM208 administration blocked the estrogens-stimulated uterine enlargement. Tamoxifen, a positive control drug, produced similar effects on the expression and activity of EST in vitro and in vivo.

CONCLUSION

The induction of EST and reduction of estrogen concentration contribute to the anti-breast cancer action of TM208 and tamoxifen. TM208 may be developed as anticancer drug for the treatment of estrogen receptor-positive breast cancer.

Breast cancer treatment and sulfotransferase

INTRODUCTION

Sustained exposure to excessive estrogen is an established risk factor for breast cancer. Sulfotransferase (SULT)-mediated sulfonation represents an effective approach for estrogen deprivation as estrogen sulfates do not bind and activate estrogen receptors (ERs). The nuclear receptor (NR) superfamily functions as a sensor for xenobiotics as well as endogenous molecules, which can regulate the expression of SULT.

AREAS COVERED

In this review, we summarize the mechanisms of SULT regulation by NRs and inactivation of estrogen by SULT. Furthermore, we discuss the potential of clinical therapy targeting SULT in breast cancer treatment. Gaps in current knowledge that require further study are also highlighted.

EXPERT OPINION

The prevention of estrogen binding to ER by antiestrogen and inhibition of estrogen synthesis by aromatase or sulfatase inhibitor have been used in clinical therapy for breast cancer. Although the induction of SULT has been proven effective to estrogen inactivation, reports on this method applied to breast cancer treatment are rare. Targeted activation of SULT may open up a new means of treating hormone-dependent breast cancer.

Modulated expression of genes encoding estrogen metabolizing enzymes by G1-phase cyclin-dependent kinases 6 and 4 in human breast cancer cells

G1-phase cell cycle defects, such as alterations in cyclin D1 or cyclin-dependent kinase (cdk) levels, are seen in most tumors. For example, increased cyclin D1 and decreased cdk6 levels are seen in many human breast tumors. Overexpression of cdk6 in breast tumor cells in culture has been shown to suppress proliferation, unlike the growth stimulating effects of its close homolog, cdk4. In addition to directly affecting proliferation, alterations in cdk6 or cdk4 levels in breast tumor cells also differentially influence levels of numerous steroid metabolic enzymes (SMEs), including those involved in estrogen metabolism. Overexpression of cdk6 in tumor cell lines having low cdk6 resulted in decreased levels of mRNAs encoding aldo-keto reductase (AKR)1C1, AKR1C2 and AKR1C3, which are hydroxysteroid dehydrogenases (HSDs) involved in steroid hormone metabolism. In contrast, increasing cdk4 dramatically increased these transcript levels, especially those encoding AKR1C3, an enzyme that converts estrone to 17β-estradiol, a change that could result in a pro-estrogenic state favoring tumor growth. Effects on other estrogen metabolizing enzymes, including cytochrome P450 (CYP) 19 aromatase, 17β-HSD2, and CYP1B1 transcripts, were also observed. Interactions of cdk6 and cdk4, but not cyclin D1, with the promoter region of a cdk-regulated gene, 17β-HSD2, were detected. The results uncover a previously unsuspected link between the cell cycle and hormone metabolism and differential roles for cdk6 and cdk4 in a novel mechanism for pre-receptor control of steroid hormone action, with important implications for the origin and treatment of steroid hormone-dependent cancers.

The cellular and molecular mechanisms by which insulin influences breast cancer risk and progression

Epidemiological studies have related hyperinsulinemia and type 2 diabetes to an increased breast cancer risk, an aggressive and metastatic phenotype, and a poor prognosis. Furthermore, diabetic retinopathy arises from pathological angiogenesis, which is also essential for breast cancer growth and metastasis. Insulin stimulates the proliferation of some human breast cancer cell lines in vitro by mechanisms that use both the phosphatidylinositol-3 kinase and the mitogen-activated protein kinase/Akt signaling pathways; it is also a cell survival (anti-apoptotic) agent and enhances tumor cell migration and invasive capacity. Hyperinsulinemia affects breast cancer cells via the endocrine system, but experimental studies suggest the importance of paracrine mechanisms operating by the effects of insulin on the secretion of adipokines from tumor-associated adipose tissue. In such a system, one adipokine, leptin, has stimulatory paracrine effects on breast cancer cell proliferation and survival, while a second, adiponectin, is inhibitory. Leptin, vascular endothelial growth factor, another insulin-regulated adipokine, and insulin itself also stimulate angiogenesis. Insulin has complex interactions with estrogens: it induces adipose stromal cell aromatase and tumor cell sex steroid hormone receptor expression and suppresses sex hormone-binding globulin, which may enhance estrogen synthesis and bioactivity with consequent promotion of estrogen-dependent breast cancer. All these actions influence the later steps in breast cancer development but genetic studies are also revealing connections between gene abnormalities related to type 2 diabetes and the initiation stage of breast carcinogenesis. Understanding the various mechanisms by which insulin participates in breast cancer cell biology provides opportunities for novel approaches to treatment.

Shift work and cancer risk: potential mechanistic roles of circadian disruption, light at night, and sleep deprivation

Shift work that includes a nighttime rotation has become an unavoidable attribute of today's 24-h society. The related disruption of the human circadian time organization leads in the short-term to an array of jet-lag-like symptoms, and in the long-run it may contribute to weight gain/obesity, metabolic syndrome/type II diabetes, and cardiovascular disease. Epidemiologic studies also suggest increased cancer risk, especially for breast cancer, in night and rotating female shift workers. If confirmed in more controlled and detailed studies, the carcinogenic effect of night and shift work will constitute additional serious medical, economic, and social problems for a substantial proportion of the working population. Here, we examine the possible multiple and interconnected cancer-promoting mechanisms as a consequence of shift work, i.e., repeated disruption of the circadian system, pineal hormone melatonin suppression by exposure to light at night, sleep-deprivation-caused impairment of the immune system, plus metabolic changes favoring obesity and generation of proinflammatory reactive oxygen species.

The mouse as a model to investigate sex steroid metabolism in the normal and pathological prostate

Metabolism of sex steroids within the prostate is an important factor affecting its growth and pathology. Mouse models with genetic gain- and especially loss-of-function have characterised different steroid metabolic pathways and their contribution to prostate pathology. With reference to the human prostate, this review aims to summarize the steroidogenic pathways in the mouse prostate as the basis for using the mouse as a model for intraprostatic steroid signalling. In this review we summarize the current information for three main components of the steroid signalling pathway in the mouse prostate: circulating steroids, steroid receptors and steroidogenic enzymes with regard to signalling via androgen, estrogen, progesterone and glucocorticoid pathways. This review reveals many opportunities for characterisation steroid metabolism in various mouse models. The knowledge of steroid metabolism within prostate tissue and in a lobe (rodent)/region (human) specific manner, will give valuable information for future, novel hypotheses of intraprostatic control of steroid actions. This review summarizes knowledge of steroid metabolism in the mouse prostate and its relevance to the human.

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.

Importance of metabolic changes induced by chemotherapy on prognosis of early-stage breast cancer patients: a review of potential mechanisms

Weight variation has been reported as a side effect of chemotherapy treatment in early breast cancer patients and has been identified as a factor of poor prognosis. Causes of weight variation during chemotherapy and mechanisms involved in the poor prognosis have been little studied. Here is reviewed the current knowledge about the main causes and mechanisms involved in body weight change. Special emphasis is placed on factors associated with weight variation which could potentially be involved in the risk of relapse in breast cancer survivors. In recent decades, some studies have investigated the causes of weight variation by studying energy balance of breast cancer patients during chemotherapy. Weight gain or loss may be the consequence of energy imbalance through different factors linked with chemotherapy, such as poor treatment tolerance, decreased muscle mass and function, or hormonal alterations. This results in body composition modifications in favour of fat gain and/or lean body mass loss. Increased adipose tissue, especially in the abdominal region, could induce metabolic disturbances such as insulin resistance, through various pathways involving adipokines. These molecules have growth properties and could therefore play a role in cancer relapse. Understanding such mechanisms is key to developing preventive strategies for improving the prognosis of early-stage breast cancer patients.

Androgens and breast cancer risk

Transdermal testosterone supplementation is a treatment option for postmenopausal women with distressful decreased libido. Side effects are minor, but there is a long-term safety concern with respect to breast cancer, as women with high testosterone serum levels appear to be at a significantly increased risk to have or to develop breast cancer within a few years. Epidemiological studies of sufficient duration to study long-term effects of testosterone supplementation are limited, both in number and in methodological quality and are, therefore, inconclusive. Preclinical studies do not provide evidence for an androgen receptor-mediated stimulating effect of androgens on breast epithelium. However, one biologically plausible possibility, which cannot be ruled out, is that exogenous androgens become mitogenic after aromatization into bioactive oestradiol, either in peripheral fat or within the breast or even within small occult tumours. The evidence available so far makes counselling women interested in testosterone supplementation for distressful low sexual desire, more of an art than science.

Metabolomics in the fields of oncology: a review of recent research

The study of all endogenously produced metabolites, known as metabolomics, is the youngest of the "omics" sciences. It is becoming increasingly clear that, of all of the "omics" techniques, metabolomic approaches will become increasingly useful in disease diagnosis and have potential power to improve our understanding of the underlying mechanisms of cancer. The primary aim of the review is to discuss the relationship between metabolomics and tumors are elucidated in detail. Then the review is also to introduce the technologies of metabolomics, especially emphasizing the application of metabolomics in the fields of oncology.

Comparison of increased aromatase versus ERα in the generation of mammary hyperplasia and cancer

Factors associated with increased estrogen synthesis increase breast cancer risk. Increased aromatase and estrogen receptor α (ERα) in both normal epithelium and ductal carcinoma in situ lesions are found in conjunction with breast cancer, leading to the idea that altered estrogen signaling pathways predispose the mammary gland to cancer development. Here, we developed a transgenic mouse that conditionally expresses aromatase in the mammary gland, and used it along with a deregulated ERα expression model to investigate the molecular pathways involved in the development of mammary gland preneoplasia and carcinoma. Both increased ERα and aromatase expression led to the development of preneoplasia, but increased preneoplasia, in addition to carcinoma, was found in aromatase overexpressing mice. Increased prevalence of mammary pathologic changes in mice expressing aromatase correlated with increased cyclin E and cyclin-dependent kinase 2 expression. Gain of both ERα and aromatase increased expression of ERα and progesterone receptor, but aromatase produced a higher increase than ERα, accompanied by higher levels of downstream target genes Ccnd1, Myc, and Tnfsf11. In summary, whereas gain of both ERα and aromatase activate abnormal growth pathways in the mammary gland, aromatase induced a wider range of abnormalities that was associated with a higher prevalence of mammary preneoplasia and cancer progression.

Pharmacogenetics of anti-estrogen treatment of breast cancer

A major effort is underway to select genetic polymorphisms potentially relevant to the clinical efficacy and safety of endocrine treatment of breast cancer. Genetic factors of the host that affect the metabolism of tamoxifen, a widely used drug for the adjuvant treatment of breast cancer, have received particular attention. Cytochrome P450 isoform 2D6 (CYP2D6) is a key step in the metabolism of tamoxifen to its active moiety endoxifen. Women with functionally deficient genetic variants of CYP2D6 who are given drugs that inhibit CYP2D6 are exposed to low endoxifen plasma levels and may enjoy reduced benefits from tamoxifen treatment. Therefore, CYP2D6 status may be an important predictor of the benefits of tamoxifen to an individual; unfortunately, the data are not uniformly concordant, and definitive evidence that would suggest the routine analysis of CYP2D6 before commencing tamoxifen treatment is not yet available. Recent research has focused on the role UDP-glucuronosyltransferases, a family of metabolizing enzymes that play an important role in the metabolic clearance of tamoxifen and of the aromatase inhibitors as well, and how interindividual differences in these enzymes may play a role in the clinical outcome upon administration of anti-estrogen treatment. In conclusion, whether a pharmacogenetic profile should be obtained prior to initiating tamoxifen therapy is currently a matter of debate, although summing up all the scientific evidence available on this issue it appears that the genetic screening would be an useful support for clinical decision making in selected patients.

Androgens and breast cancer in men and women

Abundant clinical evidence suggests that androgens normally inhibit mammary epithelial proliferation and breast growth. Clinical and nonhuman primate studies support the notion that androgens inhibit mammary proliferation and, thus, may protect from breast cancer. On the other hand, administration of conventional estrogen treatment suppresses endogenous androgens and may, thus, enhance estrogenic breast stimulation and possibly breast cancer risk. Addition of testosterone to the usual hormone therapy regimen may diminish the estrogen/progestin increase in breast cancer risk, but the impact of this combined use on mammary gland homeostasis still needs evaluation.

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.

Functional interaction of fibroblast growth factor-8, bone morphogenetic protein and estrogen receptor in breast cancer cell proliferation

Estrogen is involved in the development and progression of breast cancer. Here we investigated the effect of fibroblast growth factor (FGF)-8 on breast cancer cell proliferation caused by estrogen using human breast cancer MCF-7 cells. MCF-7 cells express estrogen receptor (ER)α, ERβ, FGF receptors, and Smad signaling molecules. Estradiol stimulated MCF-7 cell proliferation in a concentration-responsive manner, whereas BSA-bound estradiol had a weak effect on MCF-7 cell mitosis compared with the effect of free estradiol. It is notable that estrogen-induced cell proliferation was enhanced in the presence of FGF-8 and that the combined effects were reversed in the presence of an FGF-receptor kinase inhibitor or an ER antagonist. It was also revealed that FGF-8 increased the expression levels of ERα, ERβ and aromatase mRNAs, while estradiol reduced the expression levels of ERs, aromatase and steroid sulfatase in MCF-7 cells. FGF-8-induced phosphorylation of FGF receptors was augmented by estradiol, which was reversed by an ER antagonist. FGF-8-induced activation of MAPKs and AKT signaling was also upregulated in the presence of estrogen. On the other hand, FGF-8 suppressed BMP-7 actions that are linked to mitotic inhibition by activating the cell cycle regulator cdc2. FGF-8 was revealed to inhibit BMP receptor actions including Id-1 promoter activity and Smad1/5/8 phosphorylation by suppressing expression of BMP type-II receptors and by increasing expression of inhibitory Smads. Collectively, the results indicate that FGF-8 acts to facilitate cell proliferation by upregulating endogenous estrogenic actions as well as by suppressing BMP receptor signaling in ER-expressing breast cancer cells.

Aromatase, estrone sulfatase, and 17β-hydroxysteroid dehydrogenase: structure-function studies and inhibitor development

Aromatase, estrone sulfatase, and 17β-hydroxysteroid dehydrogenase type 1 are involved in the key steps of 17β-estradiol biosynthesis. Structure-function studies of aromatase, estrone sulfatase and 17β-hydroxysteroid dehydrogenase type 1 are important to evaluate the molecular basis of the interaction between these enzymes and their inhibitors. Selective and potent inhibitors of the three enzymes have been developed as antiproliferative agents in hormone-dependent breast carcinoma. New treatment strategies for hormone-dependent breast cancer are discussed.

Electron emission and product analysis of estrone: progesterone interactions studied by experiments in vitro

Recent studies showed that hormones like progesterone, testosterone, etc. can eject [Formula: see text] (solvated electrons). By means of electron transfer processes via the brain, the hormones communicate with other biological systems in the organism. The present study proves that also estrone is able to emit electrons. Their yield strongly depends on the concentration of the hormone, temperature and on the absorbed energy. The metabolites resulting from this process are likewise able to generate electrons, however with much smaller yields. The formation of the estrone metabolites is studied by HPLC-analyses. In vitro experiments with MCF-7 cells demonstrate the distinct effect of progesterone on the carcinogenity of estrone metabolites. Probable reaction mechanisms for explanation of the observed effects are postulated.

Molecular therapy of breast cancer: progress and future directions

Breast cancer is a major cause of death in Western women, with a 10% lifetime risk of the disease. Most breast cancers are estrogen-dependent. Molecular therapies for breast cancer have developed rapidly in the past few decades and future treatment strategies are being investigated. The selective estrogen receptor (ER) modulator tamoxifen, which until now has served as a standard therapy, functions not only as an estrogen antagonist but also as an estrogen agonist in terms of bone maintenance. Aromatase inhibitors have performed well in international trials and have become a new standard therapy for estrogen-dependent breast cancer. The systematic study of estrogen activation pathways suggests that the enzymes steroid sulfatase and 17beta-hydroxysteroid dehydrogenase type 1, which both have pivotal roles in estrogen biosynthesis, are promising targets; the results of a phase I trial of steroid sulfatase inhibitors are encouraging. The activity of the human epidermal growth factor receptor (HER) pathway correlates negatively with that of the ER. HER2 is overexpressed in 22% of all breast cancers. In the decade since HER2 began being targeted, the monoclonal antibody trastuzumab has been used as well as pertuzumab and HER2 vaccines. Among the estrogen-independent breast cancers, the basal-like subtype has low survival, and therapeutic improvement is a priority. Crosstalk between ER and HER2 signaling pathways means that combinatory therapies may hold the key to enhancement of treatment responses. Other molecular therapies involving functional genomics and RNA interference studies also hold promise.

Berries and ellagic acid prevent estrogen-induced mammary tumorigenesis by modulating enzymes of estrogen metabolism

To determine whether dietary berries and ellagic acid prevent 17beta-estradiol (E(2))-induced mammary tumors by altering estrogen metabolism, we randomized August-Copenhagen Irish rats (n = 6 per group) into five groups: sham implant + control diet, E(2) implant + control diet (E(2)-CD), E(2) + 2.5% black raspberry (E(2)-BRB), E(2) + 2.5% blueberry (E(2)-BB), and E(2) + 400 ppm ellagic acid (E(2)-EA). Animals were euthanized at early (6 wk), intermediate (18 wk), and late (24 wk) phases of E(2) carcinogenesis, and the mammary tissue was analyzed for gene expression changes using quantitative real-time PCR. At 6 weeks, E(2) treatment caused a 48-fold increase in cytochrome P450 1A1 (CYP1A1; P < 0.0001), which was attenuated by both BRB and BB diets to 12- and 21-fold, respectively (P < 0.001). E(2) did not alter CYP1B1 levels, but both berry and EA diets significantly suppressed it by 11- and 3.5-fold, respectively, from baseline (P < 0.05). There was a 5-fold increase in 17beta-hydroxysteroid dehydrogenase 7 (17betaHSD7), and this was moderately abrogated to approximately 2-fold by all supplementation (P < 0.05). At 18 weeks, CYP1A1 was elevated by 15-fold in E(2)-CD and only E(2)-BB reduced this increase to 7-fold (P < 0.05). Catechol-O-methyltransferase expression was elevated 2-fold by E(2) treatment (P < 0.05), and all supplementation reversed this. At 24 weeks, CYP1A1 expression was less pronounced but still high (8-fold) in E(2)-treated rats. This increase was reduced to 3.2- and 4.6-fold by E(2)-BRB and E(2)-EA, respectively (P < 0.05), but not by E(2)-BB. Supplementation did not alter the effect of E(2) on steroid receptors. The diets also significantly suppressed mammary tumor incidence (10-30%), volume (41-67%), and multiplicity (38-51%; P < 0.05). Berries may prevent mammary tumors by suppressing the levels of E(2)-metabolizing enzymes during the early phase of E(2) carcinogenesis.

Proliferation of human mammary cancer cells exposed to 27-hydroxycholesterol

The aim of the present study was to identify the possible mechanisms by which certain estradiol receptor (ER)-positive mammary tumor cells remain resistant to treatment with anti-estrogens or inhibitors of local estradiol (E(2)) production. To this end, we compared the proliferative effects on mammary cancer cells of the novel selective ER modulator 27-hydroxycholesterol (27OHC) to those of E(2), and evaluated their inhibition by ICI 182,780 (ICI). Analysis of the effects on the cell cycle of 27OHC and E(2) in the absence or presence of ICI was conducted. In ER-positive mammary tumor cells, we detected the blocking of 27OHC proliferation-stimulatory activity by simvastatin, as well as the inhibition of E(2)-stimulated proliferation by an α-fetoprotein-derived cyclic nonapeptide. The effects reported herein may be extrapolated to infiltrating mammary cancer, where the activity of local macrophages may stimulate tumor growth. We suggest that increased breast cancer growth in obese patients may be related to increased 27OHC circulatory levels.

Shu-Gan-Liang-Xue Decoction, a Chinese herbal formula, down-regulates the expression of steroid sulfatase genes in human breast carcinoma MCF-7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Shu-Gan-Liang-Xue Decoction (SGLXD), a traditional Chinese herbal formula, has been used to ameliorate hot flushes symptom in breast cancer patients for decades.

AIM OF THE STUDY

Steroid sulfatase (STS) has a crucial role in regulating the estrogen biosynthesis within breast tumors. We aimed to investigate whether SGLXD could modulate STS expression in human breast carcinoma MCF-7 cells.

MATERIALS AND METHODS

By semi-quantitative/quantitative reverse transcription-PCR, we investigated the transcript level of STS in MCF-7 cells treated with various concentrations of SGLXD. By using transient cotransfection with estrogen dependent plasmid pERE-TK-Luc and internal control plasmid pRL-TK in MCF-7 cells and dual luciferase reporter (DLR) based bioluminescent measurements, we evaluated the enzymatic activity of STS after SGLXD treatment.

RESULTS

By RT-PCR and real time PCR, the mRNA level of STS was decreased by SGLXD treatment, in the dose-dependent manner, compared to negative control (p<0.01). By DLR assay, different concentrations of SGLXD significantly inhibited the enzymatic activity of STS in MCF-7 cells dose-dependently (p<0.05).

CONCLUSIONS

SGLXD could act as a selective estrogen enzyme modulator by down-regulating the STS expression in MCF-7 cells.

17ss-Hydroxysteroid dehydrogenase type 1 as predictor of tamoxifen response in premenopausal breast cancer

17ss-Hydroxysteroid dehydrogenases (17HSDs) are involved in the local regulation of sex steroids. 17HSD1 converts oestrone (E1) to the more potent oestradiol (E2) and 17HSD2 catalyses the reverse reaction. The aim of this study was to investigate the expression of these enzymes in premenopausal breast cancers and to analyse if they have any prognostic or tamoxifen predictive value. Premenopausal patients with invasive breast cancer, stage II (UICC), were randomised to either 2years of adjuvant tamoxifen (n=276) or no tamoxifen (n=288). The median follow-up was 13.9years (range 10.5-17.5). The expression of 17HSD1 and 17HSD2 was analysed with immunohistochemistry using tissue microarrays. The enzyme expression level (-/+/++/+++) was successfully determined in 396 and 373 tumours, respectively. Women with hormone-receptor positive tumours, with low levels (-/+/++) of 17HSD1, had a 43% reduced risk of recurrence, when treated with tamoxifen (Hazard Ratio (HR)=0.57; 95% confidence interval (CI), 0.37-0.86; p=0.0086). On the other hand high expression (+++) of 17HSD1 was associated with no significant difference between the two treatment arms (HR=0.91; 95% CI, 0.43-1.95; p=0.82). The interaction between 17HSD1 and tamoxifen was significant during the first 5 years of follow-up (p=0.023). In the cohort of systemically untreated patients no prognostic importance was observed for 17HSD1. We found no predictive or prognostic value for 17HSD2. This is the first report of 17HSD1 in a cohort of premenopausal women with breast cancer randomised to tamoxifen. Our data suggest that 17HSD1 might be a predictive factor in this group of patients.

Multiple endocrine regulation by bone morphogenetic protein system

Bone morphogenetic proteins (BMPs) were originally identified with regard to their actions to regulate ectopic formation of bone and cartilage and early embryonic development. Subsequently, our research program has investigated a BMP system that exists in the mammalian ovary and plays roles in regulating numerous granulosa cell functions. BMP ligands including BMP-2, -4, -6, -7 and -15 were found to inhibit gondotropin-dependent progesterone synthesis by granulosa cells, which led to the hypothesis that BMPs are a physiological luteinization inhibitor in growing ovarian follicles during the follicular phase of the ovarian cycle. The physiological importance of the BMP system for normal mammalian reproduction has been further recognized by the discovery of aberrant reproductive phenotypes of female sheep and humans having mutated genes encoding BMP-15. Physiological roles of BMPs in the pituitary, hypothalamus, adrenal and other tissues have also been discovered. Here we discuss recent advances in the understanding of autocrine/paracrine actions of BMPs in the systemic regulation of endocrine function.

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.

Intracrinology of breast microenvironment: hormonal status in nipple aspirate fluid and its relationship to breast cancer

Breast cancer, a complex and multifactorial disease, is the most commonly diagnosed malignancy affecting women. Methods currently available for breast cancer detection have well-described limitations; in this respect, the intraductal approaches directly assess the microenvironment of the breast. Nipple aspirate fluid (NAF) can be noninvasively obtained from the breast in most women and represents a promising biological tool to assess metabolic, hormonal and molecular changes occurring in the cells lining the ducts, from which breast cancer arises. The aim of this review is to highlight the application of NAF studies in the field of biomarker discovery, which provide results useful for early detection and prevention of breast cancer risk; in fact, the analysis of NAF (mirroring the ductal-lobular microenvironment) is a reliable method for assessment of metabolic/hormonal pathways within the mammary gland, identifying biomolecular mechanisms of breast cancer initiation and progression. The intracrinology of breast microenvironment (i.e., hormonal status in NAF) may provide independent diagnostic/prognostic factors, highlighting the importance of early altered hormonal metabolism (e.g., aromatase, estrogen sulfotransferase and steroid sulfatase pathway) in relation to breast cancer initiation. The possible application of targeted therapies through the inhibition of intratumoral enzymes involved in steroid metabolism is also discussed. The intraductal approach to hormone analyses may provide a further panel of biomarkers providing clinical benefits and strengthening the armory against breast cancer.

Sex steroid metabolism polymorphisms and mammographic density in pre- and early perimenopausal women

Introduction

We examined the association between mammographic density and single-nucleotide polymorphisms (SNPs) in genes encoding CYP1A1, CYP1B1, aromatase, 17β-HSD, ESR1, and ESR2 in pre- and early perimenopausal white, African-American, Chinese, and Japanese women.

Methods

The Study of Women's Health Across the Nation is a longitudinal community-based cohort study. We analyzed data from 451 pre- and early perimenopausal participants of the ancillary SWAN Mammographic Density study for whom we had complete information regarding mammographic density, genotypes, and covariates. With multivariate linear regression, we examined the relation between percentage mammographic breast density (outcome) and each SNP (primary predictor), adjusting for age, race/ethnicity, parity, cigarette smoking, and body mass index (BMI).

Results

After multivariate adjustment, the CYP1B1 rs162555 CC genotype was associated with a 9.4% higher mammographic density than the TC/TT genotype (P = 0.04). The CYP19A1 rs936306 TT genotype was associated with 6.2% lower mammographic density than the TC/CC genotype (P = 0.02). The positive association between CYP1A1 rs2606345 and mammographic density was significantly stronger among participants with BMI greater than 30 kg/m² than among those with BMI less than 25 kg/m² (P_interaction = 0.05). Among white participants, the ESR1 rs2234693 CC genotype was associated with a 7.0% higher mammographic density than the CT/TT genotype (P = 0.01).

Conclusions

SNPs in certain genes encoding sex steroid metabolism enzymes and ESRs were associated with mammographic density. Because the encoded enzymes and ESR1 are expressed in breast tissue, these SNPs may influence breast cancer risk by altering mammographic density.