Intracrine mechanism of estrogen synthesis in breast cancer

Activation of endogenous glucocorticoids by HSD11B1 inhibits the antitumor immune response in renal cancer

Although immune-based therapies have revolutionized the management of cancer, novel approaches are urgently needed to improve their outcome. We investigated the role of endogenous steroids in the resistance to cancer immunotherapy, as these have strong immunomodulatory functions. Using a publicly available database, we found that the intratumoral expression of 11 beta-hydroxysteroid dehydrogenase type 1 (HSD11B1), which regenerates inactive glucocorticoids into active glucocorticoids, was associated with poor clinical outcome and correlated with immunosuppressive gene signatures in patients with renal cell carcinoma (RCC). HSD11B1 was mainly expressed in tumor-infiltrating immune myeloid cells as seen by immunohistochemistry in RCC patient samples. Using peripheral blood mononuclear cells from healthy donors or immune cells isolated from the tumor of RCC patients, we showed that the pharmacological inhibition of HSD11B1 improved the response to the immune checkpoint inhibitor anti-PD-1. In a subcutaneous mouse model of renal cancer, the combination of an HSD11B1 inhibitor with anti-PD-1 treatment increased the proportion of tumor-infiltrating dendritic cells. In an intrarenal mouse tumor model, HSD11B1 inhibition increased the survival of mice treated with anti-PD-1. In addition, inhibition of HSD11B1 sensitized renal tumors in mice to immunotherapy with resiquimod, a Toll-like receptor 7 agonist. Mechanistically, we demonstrated that HSD11B1 inhibition combined with resiquimod increased T cell-mediated cytotoxicity to tumor cells by stimulating the antigen-presenting capacity of dendritic cells. In conclusion, these results support the use of HSD11B1 inhibitors to improve the outcome of immunotherapy in renal cancer and highlight the role of the endogenous glucocorticoid metabolism in the efficacy of immunotherapy.

Hormonal Homologies between Canine Mammary Cancer and Human Breast Cancer in a Series of Cases

Simple Summary

There is worldwide interest in understanding the cancerous diseases that are causing increasing deaths in humans. In recent years, interest has grown in finding suitable models of different types of cancer in animals to lead the scientific community to a better understanding of the disease, in order to win the battle against cancer. The aim of this investigation was to compare breast cancer samples and canine mammary tumors from a hormonal point of view to validate the canine species as a model to study human breast cancer. There was a close similarity between premenopausal human breast cancer and canine mammary cancer in terms of hormonal receptors. In both species, all hormones assayed were increased in tumors compared to normal mammary gland samples. This research not only further supports canine mammary cancer as a spontaneous model for the study of human breast cancer but is also important in providing a deeper understanding of the hormonal pathogenesis of breast/mammary cancer in each independent species.

Abstract

The validity of spontaneous canine mammary cancer (CMC) as a natural model for the study of human breast cancer (HBC) from a hormonal point of view has never been thoroughly investigated. In this study, we analyzed the immunohistochemical expression of aromatase (Arom) and steroid receptors [estrogen receptor α (ER α), estrogen receptor β (ER β), progesterone receptor (PR) and androgen receptor (AR)] and intratumor steroid hormone levels of 17β-estradiol (E2), estrone sulfate (SO4E1), progesterone (P4), androstenedione (A4), dehydroepiandrosterone (DHEA), and testosterone (T) in 78 samples of mammary cancer—51 human breast cancer (HBC) and 27 canine mammary cancer (CMC)—and corresponding controls. Frequency of tumors expressing Arom, ERβ, PR, and AR was similar in both species, whereas ERα+ tumors were less frequent in the canine species. There was a closer similarity between premenopausal HBC and CMC. In HBC and CMC, all hormones assayed were increased in tumors compared to control samples. Intratumor androgen levels were similar in the two species, although levels of progesterone and estrogens were higher in the HBC samples than the CMC samples. Statistical associations among Arom, receptors, and hormones analyzed suggest that the major hormonal influence in both species is estrogenic through the ER, being the α isoform predominant in the human samples. Our findings further support CMC as a spontaneous model for the study of HBC, especially premenopausal HBC, although several differences, such as the more prevalent ERα immunoexpression and higher intratumor levels of estrogens and P4 in HBC, should be taken into account in comparative hormonal studies.

RORγ is a context-specific master regulator of cholesterol biosynthesis and an emerging therapeutic target in cancer and autoimmune diseases

Aberrant cholesterol metabolism and homeostasis in the form of elevated cholesterol biosynthesis and dysregulated efflux and metabolism is well recognized as a major feature of metabolic reprogramming in solid tumors. Recent studies have emphasized on major drivers and regulators such as Myc, mutant p53, SREBP2, LXRs and oncogenic signaling pathways that play crucial roles in tumor cholesterol metabolic reprogramming. Therapeutics such as statins targeting the mevalonate pathway were tried at the clinic without showing consistent benefits to cancer patients. Nuclear receptors are prominent regulators of mammalian metabolism. Their de-regulation often drives tumorigenesis. RORγ and its immune cell-specific isoform RORγt play important functions in control of mammalian metabolism, circadian rhythm and immune responses. Although RORγ, together with its closely related members RORα and RORβ were identified initially as orphan receptors, recent studies strongly support the conclusion that specific intermediates and metabolites of cholesterol pathways serve as endogenous ligands of RORγ. More recent studies also reveal a critical role of RORγ in tumorigenesis through major oncogenic pathways including acting a new master-like regulator of tumor cholesterol biosynthesis program. Importantly, an increasing number of RORγ orthosteric and allosteric ligands are being identified that display potent activities in blocking tumor growth and autoimmune disorders in preclinical models. This review summarizes the recent preclinical and clinical progress on RORγ with emphasis on its role in reprogramming tumor cholesterol metabolism and its regulation. It will also discuss RORγ functional mechanisms, context-specificity and its value as a therapeutic target for effective cancer treatment.

From Conventional to Precision Therapy in Canine Mammary Cancer: A Comprehensive Review

Canine mammary tumors (CMTs) are the most common neoplasm in intact female dogs. Canine mammary cancer (CMC) represents 50% of CMTs, and besides surgery, which is the elective treatment, additional targeted and non-targeted therapies could offer benefits in terms of survival to these patients. Also, CMC is considered a good spontaneous intermediate animal model for the research of human breast cancer (HBC), and therefore, the study of new treatments for CMC is a promising field in comparative oncology. Dogs with CMC have a comparable disease, an intact immune system, and a much shorter life span, which allows the achievement of results in a relatively short time. Besides conventional chemotherapy, innovative therapies have a large niche of opportunities. In this article, a comprehensive review of the current research in adjuvant therapies for CMC is conducted to gather available information and evaluate the perspectives. Firstly, updates are provided on the clinical-pathological approach and the use of conventional therapies, to delve later into precision therapies against therapeutic targets such as hormone receptors, tyrosine kinase receptors, p53 tumor suppressor gene, cyclooxygenases, the signaling pathways involved in epithelial-mesenchymal transition, and immunotherapy in different approaches. A comparison of the different investigations on targeted therapies in HBC is also carried out. In the last years, the increasing number of basic research studies of new promising therapeutic agents on CMC cell lines and CMC mouse xenografts is outstanding. As the main conclusion of this review, the lack of effort to bring the in vitro studies into the field of applied clinical research emerges. There is a great need for well-planned large prospective randomized clinical trials in dogs with CMC to obtain valid results for both species, humans and dogs, on the use of new therapies. Following the One Health concept, human and veterinary oncology will have to join forces to take advantage of both the economic and technological resources that are invested in HBC research, together with the innumerable advantages of dogs with CMC as a spontaneous animal model.

Human versus non-human sex steroid use in hormone replacement therapies part 1: Preclinical data

Prior to 2002, hormone replacement therapy (HRT) was considered to be an important component of postmenopausal healthcare. This was based on a plethora of basic, epidemiological and clinical studies demonstrating the health benefits of supplementation with human sex steroids. However, adverse findings from the Women's Health Initiative (WHI) studies that examined the 2 major forms of HRT in use in the US at that time - Premarin (conjugated equine estrogens; CEE) and Prempro (CEE + medroxyprogesterone acetate; MPA), cast a shadow over the use of any form of HRT. Here we review the biochemical and physiological differences between the non-human WHI study hormones - CEE and MPA, and their respective human counterparts 17β-estradiol (E₂) and progesterone (P₄). Preclinical data from the last 30 years demonstrate clear differences between human and non-human sex steroids on numerous molecular, physiological and functional parameters in brain, heart and reproductive tissue. In contrast to CEE supplementation, which is not always detrimental although certainly not as optimal as E₂ supplementation, MPA is clearly not equivalent to P₄, having detrimental effects on cognitive, cardiac and reproductive function. Moreover, unlike P₄, MPA is clearly antagonistic of the positive effects of E₂ and CEE on tissue function. These data indicate that minor chemical changes to human sex steroids result in physiologically distinct actions that are not optimal for tissue health and functioning.

Endometrial Intracrinology: Oestrogens, Androgens and Endometrial Disorders

Peripheral tissue metabolism of steroids (intracrinology) is now accepted as a key way in which tissues, such as the endometrium, can utilise inactive steroids present in the blood to respond to local physiological demands and 'fine-tune' the activation or inhibition of steroid hormone receptor-dependent processes. Expression of enzymes that play a critical role in the activation and inactivation of bioactive oestrogens (E1, E2) and androgens (A4, T, DHT), as well as expression of steroid hormone receptors, has been detected in endometrial tissues and cells recovered during the menstrual cycle. There is robust evidence that increased expression of aromatase is important for creating a local microenvironment that can support a pregnancy. Measurement of intra-tissue concentrations of steroids using liquid chromatography⁻tandem mass spectrometry has been important in advancing our understanding of a role for androgens in the endometrium, acting both as active ligands for the androgen receptor and as substrates for oestrogen biosynthesis. The emergence of intracrinology, associated with disordered expression of key enzymes such as aromatase, in the aetiology of common women's health disorders such as endometriosis and endometrial cancer has prompted renewed interest in the development of drugs targeting these pathways, opening up new opportunities for targeted therapies and precision medicine.

Profile of Steroid Receptors and Increased Aromatase Immunoexpression in Canine Inflammatory Mammary Cancer as a Potential Therapeutic Target

Canine inflammatory mammary cancer (IMC) has been proposed as a model for the study of human inflammatory breast cancer (IBC). The aims of this study were to compare the immunohistochemical expression of aromatase (Arom) and several hormone receptors [estrogen receptor α (ERα), estrogen receptor β (ERβ), progesterone receptor (PR) and androgen receptor (AR)], in 21 IMC cases vs 19 non-IMC; and to study the possible effect of letrozole on canine IMC and human inflammatory breast cancer (IBC) in vitro using IPC-366 and SUM-149 cell lines. Significant elevations of the means of Arom Total Score (TS), ERβ TS and PR TS were found in the IMC group (p = 0.025, p = 0.038 and p = 0.037, respectively). Secondary IMC tumours expressed higher levels of Arom than primary IMC (p = 0.029). Non-IMC PR- tumours contained higher levels of Arom than non-IMC PR+ tumours (p = 0.007). After the addition of letrozole, the number of IMC and IBC cells dropped drastically. The overexpression of Arom found and the results obtained in vitro further support canine IMC as a model for the study of IBC and future approaches to the treatment of dogs with mammary cancer, and especially IMC, using Arom inhibitors.

Shu-Gan-Liang-Xue Decoction Simultaneously Down-regulates Expressions of Aromatase and Steroid Sulfatase in Estrogen Receptor Positive Breast Cancer Cells

OBJECTIVE

Estradiol (E2) plays an important role in the development of breast cancer. In postmenopausal women, the estrogen can be synthesized via aromatase (CYP19) pathway and steroid-sulfatase (STS) pathway in peripheral tissues, when the production in ovary has ceased. The objective of our study was to explore the effects of Shu-Gan-Liang-Xue Decoction (SGLXD) on the expressions of CYP19 and STS in estrogen receptor positive breast cancer MCF-7 and T47D cells.

METHODS

The effects of SGLXD on the cell viability of MCF-7 and T47D were analyzed by MTT assay. By quantitative real-time RT-PCR and Western blot, we evaluated the mRNA and protein expressions of CYP19 and STS in MCF-7 and T47D cells after SGLXD treatment.

RESULTS

By MTT assay, the cell viability rates of MCF-7 and T47D were significantly inhibited by SGLXD in a dose-dependent manner, the IC50 values were 40.07 mg/ml for MCF-7 cells and 25.62 mg/ml for T47D cells, respectively. As evidenced by real-time PCR and Western blot, the high concentrations of SGLXD significantly down-regulated the expressions of CYP19 and STS both in the transcript level and the protein level.

CONCLUSION

The results suggest that SGLXD is a potential dual aromatase-sulfatase inhibitor by simultaneously down-regulating the expressions of CYP19 and STS in MCF-7 and T47D cells.

Potential utility of natural products as regulators of breast cancer-associated aromatase promoters

Aromatase, the key enzyme in estrogen biosynthesis, converts androstenedione to estrone and testosterone to estradiol. The enzyme is expressed in various tissues such as ovary, placenta, bone, brain, skin, and adipose tissue. Aromatase enzyme is encoded by a single gene CYP 19A1 and its expression is controlled by tissue-specific promoters. Aromatase mRNA is primarily transcribed from promoter I.4 in normal breast tissue and physiological levels of aromatase are found in breast adipose stromal fibroblasts. Under the conditions of breast cancer, as a result of the activation of a distinct set of aromatase promoters (I.3, II, and I.7) aromatase expression is enhanced leading to local overproduction of estrogen that promotes breast cancer. Aromatase is considered as a potential target for endocrine treatment of breast cancer but due to nonspecific reduction of aromatase activity in other tissues, aromatase inhibitors (AIs) are associated with undesirable side effects such as bone loss, and abnormal lipid metabolism. Inhibition of aromatase expression by inactivating breast tumor-specific aromatase promoters can selectively block estrogen production at the tumor site. Although several synthetic chemical compounds and nuclear receptor ligands are known to inhibit the activity of the tumor-specific aromatase promoters, further development of more specific and efficacious drugs without adverse effects is still warranted. Plants are rich in chemopreventive agents that have a great potential to be used in chemotherapy for hormone dependent breast cancer which could serve as a source for natural AIs. In this brief review, we summarize the studies on phytochemicals such as biochanin A, genistein, quercetin, isoliquiritigenin, resveratrol, and grape seed extracts related to their effect on the activation of breast cancer-associated aromatase promoters and discuss their aromatase inhibitory potential to be used as safer chemotherapeutic agents for specific hormone-dependent breast cancer.

Serum estrogen and tumor-positive estrogen receptor-alpha are strong prognostic classifiers of non-small-cell lung cancer survival in both men and women

The role of tumor estrogen receptors (ERs) and serum estrogen in lung cancer is inconclusive. We investigated the hypothesis that ERs and functional single-nucleotide polymorphisms in the estrogen biosynthesis pathway are associated with poorer lung cancer survival. Lung cancer patients (n = 305) from a National Cancer Institute-Maryland (NCI-MD) case-case cohort in the Baltimore metropolitan area were used as a test cohort. To validate, 227 cases from the NCI-MD case-control cohort and 293 cases from a Norwegian lung cancer cohort were studied. Information on demographics, tobacco and reproductive histories was collected in an interviewer-administered questionnaire. Serum estrogen, progesterone, tumor messenger RNA expression of hormone receptors and germ line DNA polymorphisms were analyzed for associations with lung cancer survival. Patients in the highest tertile of serum estrogen had worse survival in all three cohorts (P combined < 0.001). Furthermore, the variant allele of estrogen receptor alpha (ER-α) polymorphism (rs2228480) was significantly associated with increased tumor ER-α levels and worse survival in all three cohorts [hazard ratio (HR) = 2.59, 95% confidence interval (CI): 1.20- 4.01; HR = 1.76, 95% CI: 1.08-2.87 and HR = 2.85, 95% CI: 1.31-4.36). Other polymorphisms associated with lower serum estrogen correlated with improved survival. Results were independent of gender and hormone replacement therapy. We report a significant association of increased serum estrogen with poorer survival among lung cancer male and female patients. Understanding the genetic control of estrogen biosynthesis and response in lung cancer could lead to improved prognosis and therapy.

History of aromatase: saga of an important biological mediator and therapeutic target

Aromatase is the enzyme that catalyzes the conversion of androgens to estrogens. Initial studies of its enzymatic activity and function took place in an environment focused on estrogen as a component of the birth control pill. At an early stage, investigators recognized that inhibition of this enzyme could have major practical applications for treatment of hormone-dependent breast cancer, alterations of ovarian and endometrial function, and treatment of benign disorders such as gynecomastia. Two general approaches ultimately led to the development of potent and selective aromatase inhibitors. One targeted the enzyme using analogs of natural steroidal substrates to work out the relationships between structure and function. The other approach initially sought to block adrenal function as a treatment for breast cancer but led to the serendipitous finding that a nonsteroidal P450 steroidogenesis inhibitor, aminoglutethimide, served as a potent but nonselective aromatase inhibitor. Proof of the therapeutic concept of aromatase inhibition involved a variety of studies with aminoglutethimide and the selective steroidal inhibitor, formestane. The requirement for even more potent and selective inhibitors led to intensive molecular studies to identify the structure of aromatase, to development of high-sensitivity estrogen assays, and to "mega" clinical trials of the third-generation aromatase inhibitors, letrozole, anastrozole, and exemestane, which are now in clinical use in breast cancer. During these studies, unexpected findings led investigators to appreciate the important role of estrogens in males as well as in females and in multiple organs, particularly the bone and brain. These studies identified the important regulatory properties of aromatase acting in an autocrine, paracrine, intracrine, neurocrine, and juxtacrine fashion and the organ-specific enhancers and promoters controlling its transcription. The saga of these studies of aromatase and the ultimate utilization of inhibitors as highly effective treatments of breast cancer and for use in reproductive disorders serves as the basis for this first Endocrine Reviews history manuscript.

Anastrozole Use in Early Stage Breast Cancer of Post-Menopausal Women

The majority of breast cancers express the estrogen receptor and depend on estradiol (E2) for their growth. Hormonal therapy aims at depriving estrogen signaling either by using selective estrogen receptor modulators (SERM)-that interfere with the binding of E2 to its receptor (ER)-or aromatase inhibitors (AI)-that block the aromatase-dependent synthesis of E2. While SERMs are recommended for both pre- and post-menopausal patients, AIs are indicated only for post-menopausal patients. For the past 20 years, the SERM tamoxifen has been considered the "gold standard" for the treatment of hormone receptor positive breast cancers. However, tamoxifen's role is now challenged by third generation AIs, such as anastrozole, which exhibit greater efficacy in the adjuvant setting in several recently reported trials. This review will focus on anastrozole's mechanism of action, dosing, pharmacology, pharmacokinetics, and clinical applications. It will briefly discuss the clinical trials that determined anastrozole's efficacy in the treatment of advanced breast cancer (ABC) and in the neoadjuvant setting. Finally, it will present the clinical trials that established anastrozole as a frontline agent in the treatment of post-menopausal women with hormone receptor positive early breast cancer.

Effect of tumor necrosis factor-alpha on estrogen metabolism and endometrial cells: potential physiological and pathological relevance

CONTEXT

Estrogen and its metabolites play a critical role in the pathophysiology of the endometrium. The bioavailability of estrogen and estrogen metabolites in endometrial tissues depends on the expression of enzymes involved in estrogen biosynthesis and metabolism. Substantial evidence indicates that estrogen-dependent endometrial disorders are also associated with proinflammatory milieu. However, the mechanism whereby inflammation contributes to these conditions is not known.

OBJECTIVE

The objective of the study was to investigate the effect of TNF-alpha on estrogen metabolism and the expression of estrogen-metabolizing genes in human endometrial glandular epithelial cells (EM1).

DESIGN

EM1 were treated with 17beta-estradiol (E2) with or without TNF-alpha. Capillary liquid chromatography-tandem mass spectrometry analysis was used for quantitative measurement of estrogens and estrogen metabolites. Western blot analysis, reporter gene assay, and real-time RT-PCR were used to assess the expression of estrogen-metabolizing genes.

RESULTS

TNF-alpha treatment significantly increased the level of total estrogen and estrogen metabolites and significantly increased the rate of conversion of estrone (E1) into E2. TNF-alpha also enhanced the oxidative metabolism of estrogen into catecholestrogens with concomitant inhibition of their conversion into methoxyestrogens. Gene expression analysis revealed that TNF-alpha induced the expression of genes involved in E2 biosynthesis (steroidogenic factor-1 and aromatase) and activation (17beta- hydroxysteroid dehydrogenase type 1 and cytochrome P-450, 1B1) with simultaneous repression of genes involved in estrogen inactivation (17beta-hydroxysteroid dehydrogenase type 2; catechol O-methyltransferase; and nicotinamide adenine dinucleotide phosphate-quinone oxidoreductase 1).

CONCLUSION

TNF-alpha increases the local estrogen biosynthesis in human endometrial glandular cells and directs estrogen metabolism into more hormonally active and carcinogenic metabolites. These effects may impact many physiological and pathological processes that occur within the endometrium.

Activities of steroid metabolic enzymes in secretory endometria from untreated women with Polycystic Ovary Syndrome

Polycystic Ovary Syndrome (PCOS) is an endocrine-metabolic pathology related with infertility and recurrent miscarriage. We have previously shown that the endometrium of these patients can exhibit a potentially higher sensitivity to estrogen action, being estrogens important regulators of the cell cycle and tissue homeostasis. The effect of estrogens on tissues depends on their in situ availability, which is in part regulated by the activity of steroid metabolic enzymes within the tissues. Therefore, the objective of the present study was to analyze if the activity and/or expression of steroid metabolic enzymes in endometria from women with PCOS differ from controls. For this purpose, the activity of the enzymes was determined by using radiometric assays and the mRNA levels measured by semi-quantitative RT-PCR. Both assays were assessed in endometria obtained during mid secretory phase from control (CE, n=12) and PCOS women (PCOSE, n=11). For the statistical analyses, Mann-Whitney and Student's t-tests were used to compare CE and PCOSE, considering a p value <0.05 significantly different. The results showed an increase in the sulfatase activity in PCOS respect to control endometria (200+/-28pmol/mg vs. 115+/-13pmol/mgproth; p<0.05), in agreement with the higher mRNA levels found for the enzyme in PCOSE. In addition, a PCOSE exhibited lower activity of sulfotransferase respect to the control group (50+/-21pmol/mg vs. 124+/-10pmol/mgproth; p<0.05), whereas a higher level of 17beta-hydroxysteroid dehydrogenase type 1mRNA was found in PCOSE compared with the control tissues (p<0.05). The activity of 17beta-hydroxysteroid dehydrogenase type 2 and the mRNA levels of sulfotransferase were similar in both groups; meanwhile, the expression of aromatase was undetectable. These data indicate that the sulfatase pathway could play an important role in the local production of estrogens in PCOSE from secretory phase. This potentially higher bioavailability of estrogens in endometria from PCOS women could influence the deregulation of tissue homeostasis that we have previously reported, and could partially explain the poor reproductive performance observed in this group of patients.

A novel dual-target steroid sulfatase inhibitor and antiestrogen: SR 16157, a promising agent for the therapy of breast cancer

Endocrine therapy is the ideal treatment choice for estrogen receptor alpha (ERalpha)-positive breast cancer patients. Principal used therapies target either the ERalpha e.g. by selective ERalpha modulators (SERMs) such as tamoxifen or target estrogen biosynthesis with aromatase inhibitors. Steroid sulfatase (STS) plays a crucial role in formation of compounds with estrogenic properties, converting inactive sulfate-conjugated steroids to active non-conjugated forms. Steroid sulfates are considered as a reservoir for active steroids due to their prolonged half-life and increased concentration in plasma. STS is present in several tissues including the breast, and the STS the mRNA level and enzyme activity is significantly increased in ERalpha-positive breast tumors. Inhibition of STS is therefore a new approach for decreasing estrogenic steroids that stimulate breast cancer. The novel dual-acting compound SR 16157 is designed as a sulfamate-containing STS inhibitor that releases a tissue-selective SERM SR 16137. Use of a dual-target STS inhibitor and SERM represents a new strategy in the treatment of hormone-dependent breast cancer. In this study, we tested the potential of SR 16157 and SR 16137 on STS activity, cell growth and ERalpha function in MCF-7 breast cancer cells. We confirmed that the dual-target compound SR 16157 exerts STS inhibition and antiestrogenic effects. SR 16157 was a highly effective growth inhibitor, being 10 times more potent than the antiestrogens SR 16137 and tamoxifen. Relative to tamoxifen, SR 16137 displays profoundly improved ERalpha binding affinity and antiestrogenic effects on expression of estrogen-regulated genes. Thus, the dual-target SR 16157 is possibly a promising new treatment alternative, superior to tamoxifen.

A novel steroidal selective steroid sulfatase inhibitor KW-2581 inhibits sulfated-estrogen dependent growth of breast cancer cells in vitro and in animal models

We screened a series of 17beta-(N-alkylcarbamoyl)-estra-1,3,5(10)trine-3-O-sulfamate derivatives, and describe here a potent and selective steroid sulfatase (STS) inhibitor with antitumor effects in breast cancer models in vitro and in vivo. In biochemical assays using crude enzymes isolated from recombinant Chinese hamster ovary cells expressing human arylsulfatses (ARSs), one of the best compounds, KW-2581, inhibited STS activity with an IC(50) of 4.0 nM, while > 1000-fold higher concentrations were required to inhibit the other ARSs. The failure to stimulate the growth of MCF-7 human breast cancer cells as well as in uteri in ovariectomized rats indicated the lack of estrogenicity of this compound. In MCF-7 cells transfected with the STS gene, termed MCS-2 cells, KW-2581 inhibited the growth of cells stimulated by estrone sulfate (E1S) but also 5-androstene-3beta, 17beta-diol 3-sulfate (ADIOLS) and dehydroepiandrostenedione 3-sulfate. We found that oral administration of KW-2581 inhibited both E1S- and ADIOLS-stimulated growth of MCS-2 cells in a mouse hollow fiber model. In a nitrosomethylurea-induced rat mammary tumor model, KW-2581 induced regression of E1S-stimulated tumor growth as effectively as tamoxifen or another STS inhibitor, 667 Coumate. Dose-response studies in the same rat model demonstrated that more than 90% inhibition of STS activity in tumors was necessary to induce tumor shrinkage. STS activity in tumors has well correlated with that in leukocytes, suggesting that STS activity in leukocytes could be used as an easily detectable pharmacodynamic marker. These findings demonstrate that KW-2581 is a candidate for development as a therapeutic agent for the treatment of hormone receptors-positive breast cancer.

Quantitative analysis of aromatase, sulfatase and 17β-HSD1 mRNA expression in soft tissue metastases of breast cancer

Expression of the estrogen-synthesizing genes aromatase, steroid sulfatase (STS) and 17beta-hydroxysteroid dehydrogenase type1 (17beta-HSD(1)) has been shown to be up-regulated in primary breast cancer tissue but their expression status in metastatic tumor tissue has yet to be determined. The mRNA expression levels of the three estrogen-synthesizing genes as well as of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and cyclooxygenase (COX)-2, all of which have been reported to up-regulate the estrogen-synthesizing genes, were determined by means of a real-time PCR assay in 100 primary breast cancer tissues and 15 soft tissue metastases. In addition, PCR-gel electrophoresis was used to determine the proportion (%) of promoter (l.4, l.3, Pll and l.7) usage of aromatase. Aromatase and STS mRNA levels were significantly (P=0.04 and P=0.03, respectively) higher in soft tissue metastases than in primary tumors, while 17beta-HSD(1) mRNA levels tended (P=0.09) to be higher. The proportions of the promoter usages were very similar for primary tumors and soft tissue metastases, and the mRNA levels of TNF-alpha, IL-6 and COX-2 were not significantly different. Levels of aromatase, STS and 17beta-HSD(1) mRNA are up-regulated in soft tissue metastases compared to those in primary tumors, suggesting that intra-tumoral estrogen synthesis may play a significant role in the growth stimulation of tumor cells in soft tissue metastases as in primary tumors. TNF-alpha, IL-6 and COX-2, on the other hand, are unlikely to be implicated in this up-regulation.

Inhibition of steroid sulfatase activity and cell proliferation in ZR-75-1 and BT-474 human breast cancer cells by KW-2581 in vitro and in vivo

In the present study, we found that two hormone receptor-positive human breast cancer cell lines, ZR-75-1 and BT-474, naturally expressed steroid sulfatase (STS) protein and had catalytic activity to produce estrone from estrone sulfate (E1S) with a comparable level to those in human breast cancer tissues. E1S at physiological concentrations stimulated the growth of those cells. A novel steroidal STS inhibitor, KW-2581 inhibited the STS activity of ZR-75-1 cells with an IC(50) of 13 nM, a potency equal to or higher than that of the non-steroidal STS inhibitor, 667 COUMATE. The inhibitory effect of KW-2581 was enhanced by pre-incubation with STS enzyme, suggests being irreversible inhibition. KW-2581 inhibited the E1S-stimulated growth of ZR-75-1 cells with an IC(50) of 0.18 nM, but failed to inhibit the growth stimulated by 17beta-estradiol. Expression of E1S-induced progesterone receptors in ZR-75-1 cells was reduced by treatment of KW-2581 at concentrations as low as 0.1 nM. Oral administration of KW-2581 for 4 weeks caused tumor shrinkage in a mouse xenograft model. Tumor STS activity had been completely (>95%) eliminated by 24 hours after the last administration. These findings suggest that KW-2581 has considerable potential for therapeutic development as a novel anti-hormonal drug for treatment of breast cancer.

Metastatic Prostate Cancer—Does Treatment of the Primary Tumor Matter?

PURPOSE

In recent years there has been increased interest in adjuvant therapy for prostate cancer. This trend has engendered a tendency toward overlooking the issue of therapy to the primary tumor in advanced disease. We reviewed the effect of treating the principal disease bulk on overall treatment outcome in patients with advanced and metastatic cancer. Specifically we evaluated the role of surgical tumor cytoreduction.

MATERIALS AND METHODS

We performed a comprehensive literature review to evaluate the role of surgical debulking on the outcome of advanced cancer, including any published evidence supporting a benefit of this therapy for prostate cancer.

RESULTS

Even in cancers for which adjuvant chemotherapy and radiation are used liberally there is a clear benefit to optimal surgical debulking for local control and survival. The beneficial role of maximal surgical cytoreduction has been clearly demonstrated in advanced ovarian cancer and gastrointestinal carcinomatosis. Maximal debulking of brain, liver and lung metastasis has translated into longer survival. Removal of the primary tumor has been proved to increase survival in randomized trials of metastatic renal cell cancer. It appears that patients with node positive and possibly metastatic prostate cancer have a better response to androgen ablation with surgical removal of the gland.

CONCLUSIONS

Surgical cytoreduction of cancer results in a more favorable and durable response to systemic therapy. It is reasonable to explore aggressive surgical therapy for advanced prostate cancer.

Estrogen regulation of the glucuronidation enzyme UGT2B15 in estrogen receptor-positive breast cancer cells

Estrogens and androgens influence many properties of breast cancer cells; hence, regulation of local estrogen and androgen levels by enzymes involved in steroid hormone biosynthesis and metabolism would impact signaling by these hormones in breast cancer cells. In this study, we show that the UDP-glucuronosyltransferase (UGT) enzyme UGT2B15, a member of the UGT family of phase II enzymes involved in the glucuronidation of steroids and xenobiotics, is a novel, estrogen-regulated gene in estrogen receptor (ER)-positive human breast cancer cells (MCF-7, BT474, T47D, and ZR-75). UGT2B15 is the only UGT2B enzyme up-regulated by estrogen, and marked estradiol stimulation of UGT2B15 mRNA levels is observed, in a time- and dose-dependent manner. UGT2B15 stimulation by estradiol is blocked by the antiestrogen ICI182,780, but not by the translational inhibitor cycloheximide, indicating that UGT2B15 is likely a primary transcriptional response mediated through the ER. UGT2B15 up-regulation is also evoked by other estrogens (propylpyrazoletriol, genistein) and by the androgen 5alpha-dihydrotestosterone working through the ER, but not by other steroid hormone receptor ligands. Western blot and immunocytochemical analyses with several UGT2B-specific antibodies we have designed and steroid glucuronidation assays indicate a large increase in both cellular UGT2B15 protein and enzyme activity after estrogen treatment. Due to the important role of UGT enzymes in forming conjugates between steroids and glucuronic acid, thereby inactivating them and targeting them for removal, the estrogen-induced up-regulation of UGT2B15 might have a significant moderating effect on estrogen and androgen concentrations, thereby reducing their signaling in breast cancer cells.

Estrogen-responsive finger protein as a new potential biomarker for breast cancer

PURPOSE

Estrogen-responsive finger protein (Efp) is a member of RING finger-B box-Coiled Coil family and is also a downstream target of estrogen receptor alpha. Previously, Efp was shown to mediate estrogen-induced cell growth, which suggests possible involvement in the development of human breast carcinomas. In this study, we examined expression of Efp in breast carcinoma tissues and correlated these findings with various clinicopathologic variables.

EXPERIMENTAL DESIGN

Thirty frozen specimens of breast carcinomas were used for immunohistochemistry and laser capture microdissection/real-time PCR of Efp. Immunohistochemistry for Efp was also done in 151 breast carcinoma specimens fixed with formalin and embedded in paraffin wax.

RESULTS

Efp immunoreactivity was detected in breast carcinoma cells and was significantly associated with the mRNA level (n = 30). Efp immunoreactivity was positively associated with lymph node status or estrogen receptor alpha status and negatively correlated with histologic grade or 14-3-3sigma immunoreactivity (n = 151). Moreover, Efp immunoreactivity was significantly correlated with poor prognosis of breast cancer patients, and multivariate analyses of disease-free survival and overall survival for 151 breast cancer patients showed that Efp immunoreactivity was the independent marker.

CONCLUSIONS

Our data suggest that Efp immunoreactivity is a significant prognostic factor in breast cancer patients. These findings may account for an oncogenic role of Efp in the tumor progression of breast carcinoma.

Role of steroid hormones and prolactin in canine mammary cancer

In several animal studies, prolactin has been found to be essential for mammary epithelial development, and its administration has been consistently shown to increase the rate of mammary tumours. High levels of steroid hormones have also been suggested to enhance mammary cancer development. The present study investigates the levels of the following hormones in serum and in tissue homogenates in dogs bearing canine mammary tumours: prolactin (PRL), progesterone (P4), dehydroepiandrosterone (DHEA), androstenedione (A4), testosterone (T), 17beta-estradiol (17beta-E2) and estrone sulfate (S04E1). Eighty mammary tumours (40 dysplasias and benign and 40 malignant tumours) from 32 female dogs, and 10 normal mammary glands from eight female dogs without history of mammary tumours, were analysed. Prolactin and steroid hormones in serum and tissue homogenates, were analysed by enzyme immunoassays (EIA) techniques, previously validated for this animal species. Levels of prolactin in tissue homogenates were significantly different between malignant and benign mammary tumours (p<0.01). Serum prolactin concentrations were lower in the control group as compared with the group of dogs with benign tumours and in dogs with malignant tumours (p=0.01). Serum prolactin levels in dogs with benign lesions were not significantly different than those obtained from dogs with malignant tumours. Levels of steroid hormones were significantly higher in malignant tumours compared with the benign tumours and normal mammary glands (p<0.01) both in serum and homogenate determinations. Our results suggest that the canine neoplastic mammary gland could be a source of prolactin. Our hypothesis is that both prolactin and steroid hormones are involved in the growth of canine mammary cancer, and that they might have an autocrine/paracrine role in the maintenance of this disease.

Three‐Dimensional Structures of Sulfatases

The sulfatase family of enzymes catalyzes the hydrolysis of sulfate ester bonds of a wide variety of substrates. Nine human sulfatase proteins and their genes have been identified, many of which are associated with genetic disorders leading to reduction or loss of function of the corresponding enzyme. A catalytic cysteine residue, strictly conserved in prokaryotic and eukaryotic sulfatases, is modified posttranslationally into a formylglycine. Hydroxylation of the formylglycine residue by a water molecule forming the activated hydroxylformylglycine (a formylglycine hydrate or a gem-diol) is a necessary step for sulfatase activity of the enzyme. Crystal structures of three human sulfatases, arylsulfatases A and B (ARSA and ARSB) and C, also known as steroid sulfatase or estrone/dehydroepiandrosterone sulfatase (ES), have been determined. In addition, the crystal structure of a homologous bacterial arylsulfatase from Pseudomonas aeruginosa (PAS) is also available. While ARSA, ARSB, and PAS are water-soluble enzymes, ES has a hydrophobic domain and is presumed to be bound to the endoplasmic reticulum membrane. This chapter compares and contrasts four sulfatase structures and revisits the proposed catalytic mechanism in light of available structural and functional data. Examination of the ES active site reveals substrate-specific interactions previously identified in another steroidogenic enzyme. Possible influence of the lipid bilayer in substrate capture and recognition by ES is described. Finally, mapping the genetic mutations into the ES structure provides an explanation for the loss of enzyme function in X-linked ichthyosis.