Intratumoural mRNA expression of genes from the oestradiol metabolic pathway and clinical and histopathological parameters of breast cancer

Steroid Sulphatase and Its Inhibitors: Past, Present, and Future

Steroid sulphatase (STS), involved in the hydrolysis of steroid sulphates, plays an important role in the formation of both active oestrogens and androgens. Since these steroids significantly impact the proliferation of both oestrogen- and androgen-dependent cancers, many research groups over the past 30 years have designed and developed STS inhibitors. One of the main contributors to this field has been Prof. Barry Potter, previously at the University of Bath and now at the University of Oxford. Upon Prof. Potter's imminent retirement, this review takes a look back at the work on STS inhibitors and their contribution to our understanding of sulphate biology and as potential therapeutic agents in hormone-dependent disease. A number of potent STS inhibitors have now been developed, one of which, Irosustat (STX64, 667Coumate, BN83495), remains the only one to have completed phase I/II clinical trials against numerous indications (breast, prostate, endometrial). These studies have provided new insights into the origins of androgens and oestrogens in women and men. In addition to the therapeutic role of STS inhibition in breast and prostate cancer, there is now good evidence to suggest they may also provide benefits in patients with colorectal and ovarian cancer, and in treating endometriosis. To explore the potential of STS inhibitors further, a number of second- and third-generation inhibitors have been developed, together with single molecules that possess aromatase-STS inhibitory properties. The further development of potent STS inhibitors will allow their potential therapeutic value to be explored in a variety of hormone-dependent cancers and possibly other non-oncological conditions.

Influence of CYP19A1 gene expression levels in women with breast cancer: a systematic review of the literature

Breast cancer is the most frequently diagnosed malignant neoplasm in women and is considered a multifactorial disease of unknown etiology. One of the major risk factors is genetic alteration. Changes in CYP19A1 gene expression levels have been associated with increased risk and increased aggressiveness of breast cancer. Increased CYP19A1 gene expression and/or aromatase activity are among the major regulatory events for intratumoral production of estrogens in breast malignant tissues. This systematic review aimed to investigate the influence of CYP19A1 gene expression levels in women with breast cancer. The research was carried out using the PubMed, Scopus, and Web of Science databases. Searches were conducted between February 2 and May 15, 2019. Inclusion criteria were studies published between 2009 and 2019, English language publications, and human studies addressing the gene expression of CYP19A1 in breast cancer. A total of 6.068 studies were identified through PubMed (n=773), Scopus (n=2,927), and the Web of Science (n=2,368). After selecting and applying the inclusion and exclusion criteria, six articles were included in this systematic review. This systematic review provides evidence that increased or decreased levels of CYP19A1 gene expression may be related to pathological clinical factors of disease, MFS, OS, DFS, WATi, markers of metabolic function, concentrations of E1, FSH, and in the use of multiple exons 1 of the CYP19A1 gene in breast cancer.

Coumarins and Coumarin-Related Compounds in Pharmacotherapy of Cancer

Cancer is one of the most common causes of disease-related deaths worldwide. Despite the discovery of many chemotherapeutic drugs that inhibit uncontrolled cell division processes for the treatment of various cancers, serious side effects of these drugs are a crucial disadvantage. In addition, multi-drug resistance is another important problem in anticancer treatment. Due to problems such as cytotoxicity and drug resistance, many investigations are being conducted to discover and develop effective anticancer drugs. In recent years, researchers have focused on the anticancer activity coumarins, due to their high biological activity and low toxicity. Coumarins are commonly used in the treatment of prostate cancer, renal cell carcinoma and leukemia, and they also have the ability to counteract the side effects caused by radiotherapy. Both natural and synthetic coumarin derivatives draw attention due to their photochemotherapy and therapeutic applications in cancer. In this review, a compilation of various research reports on coumarins with anticancer activity and investigation and a review of structure-activity relationship studies on coumarin core are presented. Determination of important structural features around the coumarin core may help researchers to design and develop new analogues with a strong anticancer effect and reduce the potential side effects of existing therapeutics.

CYP19A1 gene expression in the peripheral blood of Brazilian women with breast cancer relapse

Background

The CYP19A1 gene, which encodes the enzyme responsible for androgen aromatization into estrogens, may play an important role in breast cancer aggressiveness. However, no study has evaluated CYP19A1 gene expression in the peripheral blood of women with relapsed breast cancer.

Methods

In this cross-sectional study, CYP19A1 gene expression was quantified by RT-PCR in the peripheral blood of 146 women with breast cancer who were first divided into two groups according to the expression of CYP19A1 (low and high); each group had 73 patients. Subsequently, women were divided into two groups: those without recurrence (control, n = 85) and those with recurrence (study, n = 61). Statistical analysis of the data was performed using ANOVA, the Mann-Whitney, Chi-square or Fisher’s exact test (p <  0.05).

Results

There were no significant differences between the relative expression of CYP19A1 mRNA in the low expression group and the high expression group according to the variables studied. There were no significant differences in CYP19A1 gene expression in the study and control groups (p = 0.8461). In the relapse group, CYP19A1 gene expression was significantly higher in the hybrid luminal subtype than in the triple-negative subtype (p = 0.0321), whereas it was significantly lower in HER2-negative cases than in HER2-positive cases (p <  0.0376). Women with locoregional recurrence showed higher expression than women with distant recurrence (p <  0.0001).

Conclusions

The present study found no significant differences between women with high and low expression of the CYP19A1 gene mRNA or between those in the study group and the control group. However, in women with recurrence, there was increased expression of CYP19A1 mRNA in those who had the luminal hybrid subtype and locoregional relapse and decreased expression in those negative for HER2.

Elevated Aromatase (CYP19A1) Expression Is Associated with a Poor Survival of Patients with Estrogen Receptor Positive Breast Cancer

Genetic variants in CYP19A1, the gene encoding aromatase, have been reported to be associated with circulating estrogen concentrations, a key risk factor for breast cancer. The mechanism underlying this association is still unclear; it has been suggested that some of these variants may alter the expression and/or activity of aromatase. Here we analyzed the expression of intra-tumoral CYP19A1 messenger RNA (mRNA) and the genotypes of rs10046, a well-characterized single nucleotide polymorphism in CYP19A1, in 138 breast cancer patients and 15 breast cancer cell lines. The genotype TT was detected in 36 patients and six cell lines, genotype CT in 55 patients and five cell lines, and genotype CC in 28 patients and four cell lines. We found no evidence for a significant association of CYP19A1 levels with rs10046 genotypes, although expression tended to be higher in tumors and cell lines with the homozygous risk genotype TT. We also found no evidence for a significant association of rs10046 genotypes with breast cancer prognosis. In contrast, high CYP19A1 expression was highly significantly associated with a poor overall, disease-free, and metastasis-free survival in estrogen receptor-positive but not negative breast cancer patients. Moreover, CYP19A1 mRNA was significantly elevated in postmenopausal patients and in patients older than 50 years, and a trend towards a positive correlation with ER status and ESR1 mRNA expression was observed. These findings highlight the key role of aromatase in estrogen receptor-positive breast cancer biology.

Estrogen receptor agonists/antagonists in breast cancer therapy: A critical review

Estrogens display intriguing tissue selective action that is of great biomedical importance in the development of optimal therapeutics for the prevention and treatment of breast cancer. There are also strong evidences to show that both endogenous and exogenous estrogens are involved in the pathogenesis of breast cancer. Tamoxifen has been the only drug of choice for more than 30years to treat patients with estrogen related (ER) positive breast tumors. There is a need therefore, for identifying newer, potential and novel candidates for breast cancer. Keeping this in view, the present review focuses on selective estrogen receptor modulators and estrogen antagonists such as sulfatase and aromatase inhibitors involved in breast cancer therapy. A succinct and critical overview of the structure of estrogen receptors, their signaling and involvement in breast carcinogenesis are herein described.

Sulfatase inhibitors for recidivist breast cancer treatment: A chemical review

Steroid sulfatase (STS) plays a momentous role in the conversion of sulfated steroids, which are biologically inactive, into biologically active un-sulfated steroid hormones, which support the development and growth of a number of hormone-dependent cancers, including breast cancer. Therefore, inhibitors of STS are supposed to be potential drugs for the treatment of breast and other steroid-dependent cancers. The present review concentrates on broad chemical classification of steroid sulfatase inhibitors. The inhibitors reviewed are classified into four main categories: Steroid sulfamate based inhibitors; Steroid non-sulfamate based inhibitors; Non-steroidal sulfamate based inhibitors; Non-steroidal non-sulfamate based inhibitors. A succinct overview of current treatment of cancer, estradiol precursors, STS enzyme and its role in breast cancer is herein described.

Synergy of novel coumarin derivatives and tamoxifen in blocking growth and inducing apoptosis of breast cancer cells

Possible synergistic effect of tamoxifen (2 μM) and hydrazinyldiene-chroman-2,4-diones (10-100 μM) was examined with an aim to create more effective treatment for ER+ breast cancer. Anti-breast cancer effect has been evaluated on the proliferation of MCF-7 breast adenocarcinoma cells using MTT and alamarBlue assays. Cell viability was evaluated after 48h-treatment and the ICs50 of the coumarin derivatives were determined. The apoptotic effect was evaluated by detection of PARP cleavage and reduced activity of the survival kinase Akt. The results demonstrated dose-dependent activity, with a percent of growth inhibition after combination treatment being significantly higher (53% to 79%, 10 μM and 100 μM, respectively) than the one in the cell lines treated with tamoxifen (29% to 37%) and the synthesized coumarin derivatives alone (11% to 68%, 10 μM and 100 μM, respectively). The ICs50 of the synthesized compounds significantly decreased in synergy with tamoxifen (33% to 51%). Coumarin derivative having thiazole moiety with additional methyl groups attached to the carbons at positions 5 and 4 in the thiazole ring showed to be the most potent, with IC50 20 µM when administered alone and 10 µM in synergy with tamoxifen. The levels of phospho-Thr308 Akt were down-regulated by the combination treatment, pointing to tyrosine kinase phosphorylation inhibition. In conclusion, the novel coumarin derivatives enhance the activity of tamoxifen and this combination may be suitable for prevention of ER+ breast cancer or development of related compounds. Further studies are needed to elucidate precisely the type of receptor involved in the activity and the mechanism of action.

A phase I dose escalation study to determine the optimal biological dose of irosustat, an oral steroid sulfatase inhibitor, in postmenopausal women with estrogen receptor-positive breast cancer

Steroid sulfatase (STS) inhibition may have a therapeutic role in suppression of endocrine-responsive breast cancer. This study aimed to determine the optimal biological dose and recommended dose (RD) of the STS inhibitor irosustat. A three-part, open-label, multicenter, dose escalation study of irosustat in estrogen receptor-positive breast cancer patients involved administration of a single dose of irosustat with a 7-day observation period; followed by a daily oral dose of irosustat for 28 days; and an extension phase, in which the daily oral dose of irosustat was continued at the discretion of the investigator and as long as the patient was benefitting from the treatment. Five doses of irosustat were tested (1, 5, 20, 40, and 80 mg) in 50 patients. After 28 days of daily administration of irosustat, all the evaluated patients in the 5, 20, 40, and 80 mg cohorts achieved ≥95 % STS inhibition in peripheral blood mononuclear cells and corresponding endocrine suppression. The maximum tolerated dose was not reached, and the 40 mg dose was established as the RD. The median time to disease progression in the 40 mg cohort was 11.2 weeks. Disease stabilization was achieved in 10 % of patients potentially indicative of drug activity. Dry skin was the most frequent adverse event. The RD of irosustat is 40 mg. Disease stabilization occurred in 10 % of this heavily pretreated patient population. A larger study is required to define an accurate response rate to irosustat as a single agent and whether co-administration with an aromatase inhibitor is needed.

Functional characterization of seven single-nucleotide polymorphisms of the steroid sulfatase gene found in a Japanese population

Steroid sulfatase (STS) is an enzyme that hydrolyzes steroid sulfates such as dehydroepiandrosterone sulfate (DHEA-S) and estrone sulfate. STS has a key role in the synthesis of steroid hormones in placenta and breast cancer cells. Recently, we have identified six novel single-nucleotide polymorphisms (SNPs) and one nonsynonymous SNP (V476M) in the STS gene in a Japanese population. To clarify the effects of SNPs in the 5'-flanking region or 5' untranslated region on transcriptional activity, a reporter gene assay was conducted. In addition, DHEA-S desulfatase activity of a variant (Met at codon 476)-type enzyme was compared with that of the wild (Wd)-type enzyme in COS-1 cells. The transcriptional activities were significantly decreased (155A) and increased (-2837A and -1588C) in MCF-7 cells. On the other hand, no significant difference was found in expression levels of STS protein or specific activities of DHEA-S desulfation between Wd and the variant enzymes. This is the first report on the effects of various SNPs in the STS gene detected in Japanese healthy subjects.

LIM-homeodomain transcription factor, Lhx2, is involved in transcriptional control of brain-specific promoter/exon 1f of the mouse aromatase gene

Neurosteroidal oestrogen has been proposed to play important roles in a variety of reproductive behaviours. Aromatase, a key enzyme in oestrogen synthesis, is localised in neural nuclei of specific brain regions and is developmentally regulated, with a transient expression peak at the perinatal period. The brain-specific promoter of the aromatase gene was analysed aiming to determine the transcriptional control mechanisms that could help explain the spatiotemporal expression. We previously reported that a 202-bp sequence, which is upstream from the transcriptional initiation site, is essential for the basal transcriptional activity. The 202-bp upstream region of brain-specific exon 1 comprises at least three types of cis-acting elements: aro-AI (Arom-Aα), aro-AII (Arom-Aβ) and aro-B (Arom-B). To identify the binding proteins for the cis-acting elements, a yeast one-hybrid screen was performed with these cis-element sequences using a mouse foetal cDNA library. Lhx2, a LIM-homeodomain protein, was identified as one of the aro-B binding proteins. The identification was further confirmed using the gel shift assay, which demonstrated binding competition of nuclear proteins to the aro-B element with a typical Lhx2-binding element. In addition, a chromatin immunoprecipitation assay with an anti-Lhx2 antibody demonstrated that Lhx2 bound to the aro-B site in vivo. A reporter assay of the brain-specific promoter demonstrated increased Lhx2-dependent promoter activity. Furthermore, the time-dependent increase in aromatase mRNA in primary cultured foetal neurones was suppressed by an small-interfering RNA-mediated knockdown of Lhx2 expression. These results show that Lhx2 is involved in the transcriptional regulation of aromatase in the rodent brain.

Steroid sulfatase: a pivotal player in estrogen synthesis and metabolism

Steroid sulfatase plays a pivotal role in regulating the formation of biologically active steroids from inactive steroid sulfates. It is responsible for the hydrolysis of estrone sulfate and dehydroepiandrosterone sulfate to estrone and dehydroepiandrosterone, respectively, both of which can be subsequently reduced to steroids with estrogenic properties (i.e. estradiol and androstenediol) that can stimulate the growth of tumors in hormone-responsive tissues of the breast, endometrium and prostate. Hence, the action of steroid sulfatase is implicated in physiological processes and pathological conditions. It has been five years since our group last reviewed the important role of this enzyme in steroid synthesis and the progress made in the development of potent inhibitors of this important enzyme target. This timely review therefore concentrates on recent advances in steroid sulfatase research, and summarises the findings of clinical trials with Irosustat (BN83495), the only steroid sulfatase inhibitor that is being trialed in postmenopausal women with breast or endometrial cancer.

Steroid sulfatase and estrogen sulfotransferase in human carcinomas

Estrogens are closely involved in the development of hormone-dependent carcinomas. Estrone is locally produced from circulating inactive estrone sulfate by steroid sulfatase (STS), while estrone is inversely inactivated into estrone sulfate by estrogen sulfotransferase (EST). Recent studies suggested importance of this STS pathway in various human carcinomas. Therefore, in this review, we summarized recent results of STS and EST in several estrogen-dependent carcinomas. STS and EST expressions were detected in the breast and endometrial carcinomas, and activation of STS pathway due to increment in STS and/or decrement in EST expressions plays important role in their estrogen-dependent growth. STS expression was also reported in the ovarian and prostate carcinomas. STS/EST status was associated with intratumoral estrogen level in the colon carcinoma, and STS-negative/EST-positive colon carcinoma patients had longer survival. Therefore, STS pathway and estrogen actions may play an important role in the development of these carcinomas, and further investigations are required.

The in vitro effects of 2-methoxyestradiol-bis-sulphamate on cell numbers, membrane integrity and cell morphology, and the possible induction of apoptosis and autophagy in a non-tumorigenic breast epithelial cell line

2-methoxyestradiol (2ME2) exerts estrogen receptor-independent anti-proliferative, anti-angiogenic and anti-tumor activity in vitro and in vivo. Due to its low bioavailability and rapid metabolic degradation, several analogues have been developed in recent years. 2-methoxyestradiol-bis-sulphamate (2-MeOE2bisMATE) is a bis-sulphamoylated derivative of 2ME2 with anti-proliferative activity. The aim of this study was to investigate cell signaling events induced by 2-MeOE2bisMATE in a non-tumorigenic cell line (MCF-12A) by analysing its influence on cell number, morphology and membrane integrity, and the possible induction of apoptosis and autophagy. Dose- and time-dependent studies revealed that 48 h exposure to 2-MeOE2bisMATE (0.4 μM) resulted in a decrease in cell numbers to 79%. A slight increase in the level of lactate dehydrogenase production was observed in the 2-MeOE2bisMATE-treated cells. Morphological studies revealed an increase in the number of cells in metaphase. Hallmarks of apoptosis were also found, namely nuclear fragmentation and apoptotic bodies. In addition, increased lysosomal staining was observed via fluorescent microscopy, suggesting the induction of another type of cell death, namely autophagy. Since 2-MeOE2bisMATE is regarded as a potential anti-cancer agent, it is also imperative to investigate the susceptibility of non-tumorigenic cells to its influence. The data generated from this study contributes to the understanding of the action that 2-MeOE2bisMATE exerts on the non-tumorigenic MCF-12A breast epithelial cell line.

Update information on drug metabolism systems--2009, part II: summary of information on the effects of diseases and environmental factors on human cytochrome P450 (CYP) enzymes and transporters

The present paper is an update of the data on the effects of diseases and environmental factors on the expression and/or activity of human cytochrome P450 (CYP) enzymes and transporters. The data are presented in tabular form (Tables 1 and 2) and are a continuation of previously published summaries on the effects of drugs and other chemicals on CYP enzymes (Rendic, S.; Di Carlo, F. Drug Metab. Rev., 1997, 29(1-2), 413-580., Rendic, S. Drug Metab. Rev., 2002, 34(1-2), 83-448.). The collected information presented here is as stated by the cited author(s), and in cases when several references are cited the latest published information is included. Inconsistent results and conclusions obtained by different authors are highlighted, followed by discussion of the major findings. The searchable database is available as an Excel file, for information about file availability contact the corresponding author.

Alternative use of multiple exons 1 of aromatase gene in cancerous and normal breast tissues from women over the age of 80 years

INTRODUCTION

Peripherally localized aromatase, which converts circulating androgens into estrogens, is important in the pathogenesis of postmenopausal breast carcinomas. We have previously shown that aromatase mRNA levels are higher in elderly breast carcinomas (EldCa) than breast carcinomas of the control group (ContCa) or normal breast tissues. Aromatase expression has been reported to be regulated through the alternative use of multiple exons 1 (exons 1a-1f and so on); however, the preferential usage of exons 1 in elderly breast tissue has never been systematically examined. In order to properly treat and protect against EldCa, the regulation mechanism of aromatase expression in elderly breast tissues should be elucidated. The aim of the present study is to elucidate whether there are any specific patterns in use of multiple exons 1 in elderly breast tissue.

METHODS

Usage of multiple exons 1 of the aromatase gene and mRNA levels of aromatase were examined by reverse transcription-polymerase chain reaction analysis in breast tissues of 38 elderly patients with breast cancer (age 80-99), and the results were compared with those in 35 patients of the control group (age 37-70). One-factor analysis of variance and the Scheffé test were used for the comparison of aromatase mRNA levels. Patterns of preferential utilization of multiple exons 1 of the aromatase gene were compared by chi2 test for independence or Fisher exact test for independence using a contingency table.

RESULTS

Exon 1d was utilized much more frequently in elderly tissue than in the control group irrespective of cancerous or normal tissue (EldCa, 36/38, 95% versus ContCa, 7/35, 20%, P < 0.0001; normal tissue of the elderly, EldNorm, 30/34, 88% versus normal tissue of controls, ContNorm, 2/29, 7%, P < 0.0001). Twenty EldCa (53%) and 12 EldNorm (35%) used both exons 1c and 1d; however, their dominance was reversed (EldCa, all 1d > 1c; EldNorm, all 1c > 1d).

CONCLUSIONS

Elderly breast tissues exhibited specific patterns in use of multiple exons 1, which at least partly explained the higher aromatase levels in EldCa. The mechanisms of how these specific patterns occur during aging and carcinogenesis should be further examined.

Transcriptional control of human steroid sulfatase

Steroid sulfatase (STS) is a membrane-bound microsomal enzyme that hydrolyzes various alkyl and aryl steroid sulfates, leading to the in situ formation of biologically active hormones. The entire human STS gene spans over approximately 200kbp of which the first 100kbp include the regulatory region, while the STS-coding region is located downstream. Previous studies indicated that STS expression, in different human tissues, could be regulated by at least six different promoters associated with alternative first exons. Here, we describe two new splicing patterns: the first, found in the prostatic cell line PC3, is based upon a partially coding new first exon (0d) that is spliced to a new second exon (1e). The second variant was found in the ovary and it is characterized by the novel splicing of the untranslated exon 0b to exon 0c, which is then spliced to the common exon 1b. We also report the results of a multiplex ligation-dependent probe amplification (RT-MLPA) analysis for the simultaneous detection, in qualitative and/or semi-quantitative terms, of the transcription patterns of STS in different tissues.

Expression level of enzymes related to in situ estrogen synthesis and clinicopathological parameters in breast cancer patients

In order to evaluate the importance of estrogen production in tumor and surrounding tissues, we measured mRNA expression levels of 5 enzymes participating to estrogen synthesis in situ and 4 breast cancer-related proteins in 27 pairs of tumor and non-malignant tissues. Steroid sulfatase (STS) mRNA was more frequently detected in tumor tissues rather than in their non-malignant counterparts. Estrogen sulfotransferase (EST) was constantly expressed with high level not only in tumor tissues but also in their surrounding non-malignant counterparts. In contrast, mRNA expression levels of aromatase, and 17beta-hydroxysteroid dehydrogenase type I and II were relatively low and detected only in small proportion of the patients. We also measured the mRNA expression levels of the same nine genes in tumor tissues of 197 breast cancer patients, and analyzed relationship between the mRNA expression level and the clinicopathological parameters. The mRNA expression levels of STS, aromatase and erbB2 in tumor tissues increased as breast cancer progressed. The tumoral mRNA expression levels of STS, estrogen receptor beta, and erbB2 in patients with recurrence were higher than those in patients without recurrence. Upregulation of STS expression plays an important role in tumor progression of human breast cancer and is considered to be responsible for estrogen production in tumor and surrounding tissues.

A review of coumarin derivatives in pharmacotherapy of breast cancer

The coumarin (benzopyran-2-one, or chromen-2-one) ring system, present in natural products (such as the anticoagulant warfarin) that display interesting pharmacological properties, has intrigued chemists and medicinal chemists for decades to explore the natural coumarins or synthetic analogs for their applicability as drugs. Many molecules based on the coumarin ring system have been synthesized utilizing innovative synthetic techniques. The diversity oriented synthetic routes have led to interesting derivatives including the furanocoumarins, pyranocoumarins, and coumarin sulfamates (COUMATES), which have been found to be useful in photochemotherapy, antitumor and anti-HIV therapy, and as stimulants for central nervous system, antibacterials, anti-inflammatory, anti-coagulants, and dyes. Of particular interest in breast cancer chemotherapy, some coumarins and their active metabolite 7-hydroxycoumarin analogs have shown sulfatase and aromatase inhibitory activities. Coumarin based selective estrogen receptor modulators (SERMs) and coumarin-estrogen conjugates have also been described as potential antibreast cancer agents. Since breast cancer is the second leading cause of death in American women behind lung cancer, there is a strong impetus to identify potential new drug treatments for breast cancer. Therefore, the objective of this review is to focus on important coumarin analogs with antibreast cancer activities, highlight their mechanisms of action and structure-activity relationships on selected receptors in breast tissues, and the different methods that have been applied in the construction of these pharmacologically important coumarin analogs.

In situ levels of oestrogen producing enzymes and its prognostic significance in postmenopausal breast cancer patients

BACKGROUND

The risk of developing breast cancer is strongly correlated with the overall exposure to oestrogen and most tumours are more or less dependent on oestrogen for their growth. A great majority of breast cancers occur after menopause when the ovaries have ceased to be functional, yet breast tumours in postmenopausal women maintain high intratumoural oestrogen concentrations, primarily through enzymatic conversion of androgenic precursors.

PATIENTS

with a hormone dependent tumour generally receive the anti-oestrogen tamoxifen that mediate its anti-tumour effect by competing with oestrogen for binding to the oestrogen-receptor (ER). We therefore propose that the levels of oestrogen producing enzymes may affect the prognosis in postmenopausal breast cancer patients treated with tamoxifen.

METHODS

We measured the mRNA and protein levels of aromatase and sulfatase by real-time PCR (n=161) and immunohistochemistry (n=131) in postmenopausal women with breast cancer.

RESULTS

A significant better recurrence-free survival was detected in patients with weak or high protein expression of stromal aromatase (P=0.0008), as also demonstrated by a decreased relative risk (RR=0.50, CI=0.33-0.76, P=0.003). When we combined patients with weak and high stromal aromatase and selected only ER-positive patients, the improved prognosis was even more evident (P=0.0000) and was shown to be a significant prognostic factor in a multivariate Cox-model (HR=0.15, CI=0.06-0.39, P=0.000). The mRNA expression of aromatase and sulfatase, as well as the protein expression of sulfatase revealed no prognostic significance.

CONCLUSION

Protein expression of stromal aromatase may serve as a significant prognostic marker in ER-positive patients.

Immunohistochemical analysis of steroid sulfatase in human tissues

Steroid sulfatase (EC 3.1.6.2) is an enzyme that removes the sulfate group from 3beta-hydroxysteroid sulfates. This enzyme is best known for its role in estrogen production via the fetal adrenal-placental pathway during pregnancy; however, it also has important functions in other physiological and pathological steroid pathways. The objective of this study was to examine the distribution of steroid sulfatase in normal human tissues and in breast cancers using immunohistochemistry, employing a newly developed steroid sulfatase antibody. A rabbit polyclonal antiserum was generated against a peptide representing a conserved region of the steroid sulfatase protein. In Western blotting experiments using human placental microsomes, this antiserum crossreacted with a 65 kDa protein, the reported size of steroid sulfatase. The antiserum also crossreacted with single protein bands in Western blots of microsomes from two human breast cancer cell lines (MDA-MB-231 and MCF-7) and from rat liver; however, there were some size differences in the immunoreactive bands among tissues. The steroid sulfatase antibody was used in immunohistochemical analyses of individual human tissue slides as well as a human tissue microarray. For single tissues, human placenta and liver showed strong positive staining against the steroid sulfatase antibody. ER+/PR+ breast cancers also showed relatively strong levels of steroid sulfatase immunoreactivity. Normal human breast showed moderate levels of steroid sulfatase immunoreactivity, while ER-/PR- breast cancer showed weak immunoreactivity. This confirms previous reports that steroid sulfatase is higher in hormone-dependent breast cancers. For the tissue microarray, most tissues showed some detectable level of steroid sulfatase immunoreactivity, but there were considerable differences among tissues, with skin, liver and lymph nodes having the highest immunoreactivity and brain tissues having the lowest. These data reveal the utility of immunohistochemistry in evaluation of steroid sulfatase activity among tissues. The newly developed antibody should be useful in studies of both humans and rats.

Steroid sulfatase in breast carcinoma and change of serum estrogens levels after operation

Fifty-four breast carcinomas were studied for the expression of steroid sulfatase (STS) by immunohistochemistry. Correlations between the expression of STS and clinical parameters were determined. Concentrations of serum estrone (E1), estrone sulfate (E1S), estradiol (E2) and estradiol sulfate (E2S) in 12 postmenopausal patients with STS positive tumor were measured by radioimmunoassay. Positive expression of STS was obtained in 72% of tumors. The incidence of STS positive tumor was significantly more frequent in postmenopausal patients (p = 0.01). In our postmenopausal patients, serum E1, E1S, E2, E2S and E2S levels in STS high score group were decreased postoperatively, and those in both STS high and low score group were stabilized after operation. Results from this study suggest STS in breast carcinoma may play an important enzyme of the intratumoral estrogen synthesis in postmenopausal women, and it would be interesting that locally produced STS might be closely related to the control of estrogens environment in breast carcinoma.

Phase I study of STX 64 (667 Coumate) in breast cancer patients: the first study of a steroid sulfatase inhibitor

PURPOSE

Inhibition of steroid sulfatase (STS), the enzyme responsible for the hydrolysis of steroid sulfates, represents a potential novel treatment for postmenopausal women with hormone-dependent breast cancer. Estrone and DHEA are formed by this sulfatase pathway and can be converted to steroids (estradiol and androstenediol, respectively), which have potent estrogenic properties.

EXPERIMENTAL DESIGN

STX64 (667 Coumate), a tricylic coumarin-based sulfamate that irreversibly inhibits STS activity, was selected for entry into the first phase I trial of a STS inhibitor in postmenopausal women with breast cancer. STX64 was administered orally (nine patients at 5 mg and five patients at 20 mg) as an initial dose followed 1 week later by 3 x 2 weekly cycles, with each cycle comprising daily dosing for 5 days followed by 9 days off treatment. Blood and tumor tissue samples were collected for the assessment of STS activity and serum was obtained for steroid hormone measurements before and after treatment.

RESULTS

The median inhibition of STS activity by STX64 was 98% in peripheral blood lymphocytes (PBL) and 99% in breast tumor tissue at the end of the 5-day dosing period. As expected, serum concentrations of estrone, estradiol, androstenediol, and DHEA all decreased significantly from pretreatment levels. Unexpectedly, androstenedione and testosterone concentrations also decreased. Four patients, all of whom had previously progressed on aromatase inhibitors, showed evidence of stable disease for 2.75 to 7 months. The drug was well tolerated with only minor drug-related adverse events recorded.

CONCLUSION

STX64 is a potent, well-tolerated STS inhibitor. It inhibits STS activity in PBLs and tumor tissues and causes significant decreases in serum concentrations of steroids with estrogenic properties.

The role of aromatase and 17-β-hydroxysteroid dehydrogenase type 1 mRNA expression in predicting the clinical outcome of human breast cancer

INTRODUCTION

There is substantial evidence that breast cancer tissue contains all the enzymes responsible for the local biosynthesis of estrogens from circulating precursors. The cytochrome P-450 aromatase enzyme complex is responsible for the conversion of C19 androgens to estrogens and 17-beta-hydroxysteroid dehydrogenase (17-I(2)-HSD) type 1 catalyses the inter-conversion of estrone to the biologically more potent estradiol. The gene encoding for the cytochrome P-450 aromatase is known as CYP19 (15q21.2). It is well established that increased exposure to local estrogens is an important risk factor in the genesis and growth of breast cancer. The aim of this study is to investigate the relationship between CYP19 and 17-beta-HSD type 1A mRNA expression and clinico-pathological parameters of human breast cancer.

METHODS

One hundred and twenty seven tumor tissues and 33 normal tissues were analyzed. The levels of transcription of CYP19 and 17-beta-HSD type 1 were determined using real-time quantitative PCR. The mRNA expression was normalized against CK19. Levels of expression were analyzed against tumorâ's stage, grade, nodal status, local relapse, distant metastasis and survival over a 120A months follow up period. In addition, the levels were analyzed against estrogen receptor (ER) and HER1-4 status.

RESULTS

Overall, high tumor levels of mRNA expression of CYP19 and 17-beta-HSD type 1 correlated with poor survival (p=0.0105 and p=0.0182, respectively). Increased levels of CYP19 mRNA expression positively correlated with disease progression as levels were significantly higher in samples of patients who had distant metastasis and local recurrence and/or died of breast related causes when compared to those who were disease free for >10 years (p=0.0015). We also observed higher levels of CYP19 mRNA in tumor samples compared to normal breast tissue. However, this reached statistical significance only when comparing grade 1 tumors with normal tissue (p=0.01). There was no correlation between CYP19á mRNA expression and tumor stage, lymph node status and tumor grade. There was however a trend for a positive correlation between CYP19 and ER mRNA expressions (p=0.06). No significant difference in 17-beta-HSD type 1 expression between normal and cancerous tissues was observed. In tumor samples, we observed an increase in levels correlating with tumor's grade. This correlation was statistically significant when we compared grade 1 with grade 2 and grade 1 with grade 3 (p=0.0031 and 0.0251, respectively).

CONCLUSION

Our study shows that higher levels of the enzymes responsible for the local biosynthesis of estrogens especially aromatase are associated with a poor clinical outcome in patients with breast cancer.

Estrogen-metabolizing enzymes in breast cancers from women over the age of 80 years

CONTEXT

Aromatase, steroid sulfatase, and 17beta-hydroxysteroid dehydrogenase type 1 (HSD-1) peripherally up-regulate, whereas estrogen sulfotransferase (EST) and HSD-2 down-regulate, the synthesis of active and more potent estrogens. These estrogen-metabolizing enzymes (EMEs) are important in postmenopausal breast cancers, but have never been systematically examined in breast cancers of the elderly.

OBJECTIVE AND DESIGN

mRNA levels of EMEs in cancerous and normal breast tissues from 39 elderly patients (age, 80-99 yr) were compared with those from 39 controls (age, 37-70 yr) or compared according to estrogen (ER)/progesterone (PR) receptor status.

RESULTS

Aromatase levels were higher in cancers of the elderly (EldCa) than in normal tissue of the elderly (P = 0.0008) or cancers of controls (P = 0.0033). In contrast, levels of steroid sulfatase and EST were higher in cancers of controls than normal tissue of controls (P = 0.0046 and P < 0.0001, respectively) or EldCa (P = 0.0001 and P < 0.0001, respectively). Levels of HSD-1 and HSD-2 did not differ significantly between any two of the categories. Among EldCa, HSD-1 levels were higher in ER/PR-positive than in ER/PR-negative carcinomas, whereas EST and HSD-2 exhibited opposite results.

CONCLUSIONS

The importance of aromatase is relatively increased in EldCa. ER/PR-positive EldCa exhibited a pattern of EMEs more beneficial to the production of estrogen than did ER/PR-negative EldCa. The specific pattern exhibited in EldCa may elucidate the role of EMEs in the absence of ovarian estrogens in the pathogenesis of breast cancer.

Effects of anastrozole on the intratumoral gene expression in locally advanced breast cancer

Intratumoral levels of E1 (oestrone), E1S (oestrone sulphate) and E2 (oestradiol) are significantly reduced by treatment with the aromatase inhibitor anastrozole regardless of treatment response. The purpose of the present pilot study was to look for additional markers of biochemical response to aromatase inhibitors on mRNA expression level. Whole genome expression was studied using microarray analysis of breast cancer tissue from 12 patients with locally advanced tumors, both before and following 15 weeks of treatment with the aromatase inhibitor anastrozole (Arimidex). Intratumoral mRNA levels for a subset of genes coding for steroid metabolizing enzymes, hormone receptors and some growth mediators involved in cell cycle control were analysed by quantitative RT-PCR. There was a correlation between the two methods for some but not all genes. The mRNA expression levels of the different genes were correlated to each other and to the intratumoral levels of E1, E2 and E1S, before and after the treatment. Notably, a correlation of the E1/E2 metabolic ratio to the mRNA levels of CYP19A1 was observed before treatment (r=0.745, p<0.005). Whole genome expression analysis of these 12 breast cancer patients revealed similar tumor classification to previously published larger studies. Tumors with no or low expression of ESR1 (oestrogen receptor) clustered together and were characterized by a strong basal-like signature highly expressing keratins 5/17, cadherin 3, frizzled and apolipoprotein D, among others. The luminal epithelial tumor cluster, on the other hand, highly expressed ESR1, GATA binding protein 3 and N-acetyl transferase. An evident ERBB2 cluster was observed due to the marked over-expression of the ERBB2 gene and GRB7 and PPARBP in this patient material). Using significance analysis of microarrays (SAM), we identified 298 genes significantly differently expressed between the partial response and progressive disease groups.

Steroid sulfatase: molecular biology, regulation, and inhibition

Steroid sulfatase (STS) is responsible for the hydrolysis of aryl and alkyl steroid sulfates and therefore has a pivotal role in regulating the formation of biologically active steroids. The enzyme is widely distributed throughout the body, and its action is implicated in physiological processes and pathological conditions. The crystal structure of the enzyme has been resolved, but relatively little is known about what regulates its expression or activity. Research into the control and inhibition of this enzyme has been stimulated by its important role in supporting the growth of hormone-dependent tumors of the breast and prostate. STS is responsible for the hydrolysis of estrone sulfate and dehydroepiandrosterone sulfate to estrone and dehydroepiandrosterone, respectively, both of which can be converted to steroids with estrogenic properties (i.e., estradiol and androstenediol) that can stimulate tumor growth. STS expression is increased in breast tumors and has prognostic significance. The role of STS in supporting tumor growth prompted the development of potent STS inhibitors. Several steroidal and nonsteroidal STS inhibitors are now available, with the irreversible type of inhibitor having a phenol sulfamate ester as its active pharmacophore. One such inhibitor, 667 COUMATE, has now entered a phase I trial in postmenopausal women with breast cancer. The skin is also an important site of STS activity, and deficiency of this enzyme is associated with X-linked ichthyosis. STS may also be involved in regulating part of the immune response and some aspects of cognitive function. The development of potent STS inhibitors will allow investigation of the role of this enzyme in physiological and pathological processes.

Regulation of aromatase activity by cytokines, PGE2 and 2-methoxyoestrone-3-O-sulphamate in fibroblasts derived from normal and malignant breast tissues

Synthesis of oestrone from androstenedione within tumours, by the aromatase enzyme complex, is an important source of oestrogen that is available to support the growth of hormone-dependent breast tumours. In view of the central role that the aromatase enzyme has in oestrogen synthesis there has been considerable interest in understanding its regulation and developing inhibitors to block its action. In the present study we have derived fibroblasts from breast tumours (TFs), tissue proximal to tumours (PFs) and reduction mammoplasty tissue (RMFs) and used them to investigate the regulation of aromatase activity by PGE(2), IL-6 plus its soluble receptor (SR) or TNFalpha. In addition we have examined the ability of 2-methoxyoestrone sulphamate (2-MeOEMATE), a compound which alters microtubule stability, to block the stimulation of aromatase activity by these factors. Basal aromatase activity in PFs was significantly higher (p<0.001) than in TFs or RMFs. The combination of IL-6 plus SR or TNFalpha produced the greatest stimulation of aromatase activity in TFs (up to 61-fold) while having a much lower stimulatory effects on aromatase activity in PFs (up to 60% increase) or RMFs (up to 192% increase). 2-MeOEMATE reduced basal aromatase activity in TFs by 87% and completely abrogated the ability of PGE(2), IL-6 plus SR or TNFalpha to stimulate aromatase activity in these fibroblasts. Results from these studies indicate that while PFs have the highest level of non-stimulated aromatase activity, aromatase activity in TFs shows the greatest response to cytokines. These findings suggest that intrinsic difference may exist for the different types of fibroblasts in the way in which they respond to regulatory factors. The ability of 2-MeOEMATE to block cytokine stimulated aromatase activity suggests that, in addition to its other anti-cancer properties, this compound may also act to inhibit cytokine-stimulated aromatase activity in breast tumours.

The effects of 2-methoxyoestrogen sulphamates on the in vitro and in vivo proliferation of breast cancer cells

2-Methoxyoestrogen sulphamates are a new class of compounds, which inhibit breast cancer cell proliferation and are also potent inhibitors of steroid sulphatase (STS) activity. In the present study, we have used two cell proliferation assays (MTS and AB) to identify potent new compounds in this class. Similar IC(50) values were obtained using these assays with two of the most potent compounds identified being 2-methoxyoestradiol-bis-sulphamate (2-MeOE2bisMATE) and 2-methoxyoestradiol-17beta-cyanomethyl-3-O-sulphamate (2-MeOE2CyMATE). Both compounds inhibited the proliferation of MCF-7 (ER+) and MDA-MB-231 (ER-) breast cancer cells. Using the AB assay, which allows repeat measurements of cell proliferation without killing cells, both compounds were shown to inhibit cell proliferation in an irreversible manner. As STS may be involved in the removal of the sulphamoyl moiety of these compounds, which could reduce their potency, their ability to inhibit the proliferation of MCF-7 cells transfected with the cDNA for STS was also examined. Although the STS activity was 20-fold higher in these cells than in non-transfected MCF-7 cells, no decrease in the ability of these compounds to inhibit cell proliferation was detected. To test the efficacy of these compounds in vivo, nude mice were inoculated with MCF-7 cells in Matrigel and stimulated to grow with oestradiol. Three weeks after the oral administration of 2-MeOE2bisMATE or 2-MeOE2CyMATE (20mg/kg/day, 5 days/week) tumour volumes had regressed by 52% and 22%, respectively. Both compounds also inhibited liver and tumour STS activity by >90%. The potent anti-proliferative effects of these compounds, and their ability to inhibit tumour growth and STS activity in vivo, indicates that they are suitable for development as novel therapeutic agents, which should be active against a wide range of cancers.

Gene Expression Profiling of Breast Cancer in Relation to Estrogen Receptor Status and Estrogen-Metabolizing Enzymes: Clinical Implications

Interactions between luminal epithelial cells and their surrounding microenvironment govern the normal development and function of the mammary gland. Estradiol plays a key role in abnormal intracellular signaling, which contributes to the development and progression of breast tumors. The present article summarizes the results from a microarray whole genome gene expression analysis as well as a quantitative analysis of the mRNA expression of members of the estradiol metabolic and signaling pathways in the tumors of postmenopausal breast cancer patients. The analysis of the variation in whole genome gene expression resulted in a tumor classification comprising several distinct groups with distinct expression of the estrogen receptor (ER). The parallel study on the expression of only nine mRNA transcripts of members of the estradiol pathways resulted in two main clusters, representing ER− and ER tumors. The mRNA expression of the estradiol-metabolizing enzymes did not follow the expression of the ER in all cases, leading to the recognition of several further subclasses of tumors. When the tumor classes obtained by whole genome gene expression analysis were compared with those obtained by independent quantitation of the estradiol-metabolizing enzymes, a statistically significant association between both classification groups was observed. These findings point to a possible association between development of a tumor with a particular expression profile and its capacity to synthesize estradiol as measured by the expression of the transcripts for the necessary key enzymes. Further, whole genome expression patterns were studied in 12 patients treated with anastrozole. Using significance analysis of microarrays, we identified 298 genes significantly differently expressed between partial response and progressive disease groups.

Pharmacokinetics of the nonsteroidal steroid sulphatase inhibitor 667 COUMATE and its sequestration into red blood cells in rats

Breast cancer is a major cause of mortality in Western countries and there is an urgent requirement for novel treatment strategies. The nonsteroidal sulphatase inhibitor 667 COUMATE inhibits hepatic steroid sulphatase and growth of oestrone sulphate stimulated tumours in the nitrosomethylurea-induced rat mammary model. Other compounds that contain an aryl sulphamate moiety, for example, oestrone-3-O-sulphamate, are sequestered into red blood cells (RBCs). The aims of this study were to determine the pharmacokinetics of 667 COUMATE and to investigate its sequestration into RBCs. We administered a single p.o. or i.v. dose (10 mg kg⁻¹) of 667 COUMATE to rats and used a high-performance liquid chromatography method to measure the levels of the agent and its putative metabolites in plasma. 667 COUMATE had a bioavailability of 95% and could be detected in plasma for up to 8 h. Using two independent analytical methods, we demonstrated that 667 COUMATE is sequestered by RBCs both ex vivo and in vivo. Previous investigations have revealed that 667 COUMATE is rapidly degraded in plasma ex vivo. In this study, we demonstrate that 667 COUMATE is stabilised due to its sequestration into RBCs. In conclusion, the pharmacological efficacy and high oral bioavailability of 667 COUMATE may be partly a consequence of the ability of RBCs to both protect the agent from metabolic degradation and facilitate its transport to tissues. These data support the further clinical evaluation of this novel endocrine therapeutic agent.