17ß-Hydroxysteroid dehydrogenases types 1 and 2: Enzymatic assays based on radiometric and mass-spectrometric detection.

The 17ß-hydroxysteroid dehydrogenase type 1 (HSD17B1) has a key role in estrogen biosynthesis as it catalyzes the reduction of estrone to the most potent estrogen, estradiol. Estradiol has a high affinity for estrogen receptors and thus stimulates their transactivation, which leads to cell proliferation and numerous other effects. HSD17B2 catalyzes the oxidation of estradiol to the less potent estrone, thereby decreasing estrogen receptor activation, which results in reduction of estrogen-associated effects. HSD17B1 and HSD17B2 overexpressing E.coli homogenates or recombinant enzymes can be used for screening and development of drugs against various pathologies such as cancer, endometriosis or osteoporosis. Here we describe the preparation of HSD17B1 and HSD17B2 bacterial homogenates and purified recombinant HSD17B1 protein as enzyme sources as well as enzymatic assays based on radiometric and mass-spectrometric detection for enzyme characterization.

The Co-Expression of Estrogen Receptors ERα, ERß, and GPER in Endometrial Cancer.

Estrogens have important roles in endometrial cancer (EC) and exert biological effects through the classical estrogen receptors (ERs) ERα and ERß, and the G-protein-coupled ER, GPER. So far, the co-expression of these three types of ERs has not been studied in EC. We investigated ERα, ERß, GPER mRNA and protein levels, and their intracellular protein distributions in EC tissue and in adjacent control endometrial tissue. Compared to control endometrial tissue, immunoreactivity for ERα in EC tissue was weaker for nuclei with minor, but unchanged, cytoplasmic staining; mRNA and protein levels showed decreased patterns for ERα in EC tissue. For ERß, across both tissue types, the immunoreactivity was unchanged for nuclei and cytoplasm, although EC tissues again showed lower mRNA and protein levels compared to adjacent control endometrial tissue. The immunoreactivity of GPER as well as mRNA levels of GPER were unchanged across cancer and control endometrial tissues, while protein levels were lower in EC tissue. Statistically significant correlations of estrogen receptor α (ESR1) versus estrogen receptor ß (ESR2) and GPER variant 3,4 versus ESR1 and ESR2 was seen at the mRNA level. At the protein level studied with Western blotting, there was significant correlation of ERα versus GPER, and ERß versus GPER. While in clinical practice the expression of ERα is routinely tested in EC tissue, ERß and GPER need to be further studied to examine their potential as prognostic markers, provided that specific and validated antibodies are available.

Physiological Concentrations of Cimicifuga racemosa Extract Do Not Affect Expression of Genes Involved in Estrogen Biosynthesis and Action in Endometrial and Ovarian Cell Lines.

In postmenopausal women, estrogen levels exclusively depend on local formation from the steroid precursors dehydroepiandrosterone sulfate and estrone sulfate (E1-S). Reduced estrogen levels are associated with menopausal symptoms. To mitigate these symptoms, more women nowadays choose medicine of natural origin, e.g., Cimicifuga racemosa (CR), instead of hormone replacement therapy, which is associated with an increased risk of breast cancer, stroke, and pulmonary embolism. Although CR treatment is considered safe, little is known about its effects on healthy endometrial and ovarian tissue and hormone-dependent malignancies, e.g., endometrial and ovarian cancers that arise during menopause. The aim of our study was to examine the effects of CR on the expression of genes encoding E1-S transporters and estrogen-related enzymes in control and cancerous endometrial and ovarian cell lines. CR affected the expression of genes encoding E1-S transporters and estrogen-related enzymes only at very high concentrations, whereas no changes were observed at physiological concentrations of CR. This suggests that CR does not exert estrogenic effects in endometrial and ovarian tissues and probably does not affect postmenopausal women's risks of endometrial or ovarian cancer or the outcomes of endometrial and ovarian cancer patients.

In the Model Cell Lines of Moderately and Poorly Differentiated Endometrial Carcinoma, Estrogens Can Be Formed via the Sulfatase Pathway.

Endometrial cancer (EC) is the most common gynecological malignancy in resource-abundant countries. The majority of EC cases are estrogen dependent but the mechanisms of estrogen biosynthesis and oxidative metabolism and estrogen action are not completely understood. Here, we evaluated formation of estrogens in models of moderately and poorly differentiated EC: RL95-2 and KLE cells, respectively. Results revealed high expression of estrone-sulfate (E1-S) transporters (SLCO1A2, SLCO1B3, SLCO1C1, SLCO3A1, SLC10A6, SLC22A9), and increased E1-S uptake in KLE vs RL95-2 cells. In RL95-2 cells, higher levels of sulfatase and better metabolism of E1-S to E1 were confirmed compared to KLE cells. In KLE cells, disturbed balance in expression of HSD17B genes led to enhanced activation of E1 to E2, compared to RL95-2 cells. Additionally, increased CYP1B1 expression and down-regulation of genes encoding phase II metabolic enzymes: COMT, NQO1, NQO2, and GSTP1 suggested decreased detoxification of carcinogenic metabolites in KLE cells. Results indicate that in model cell lines of moderately and poorly differentiated EC, estrogens can be formed via the sulfatase pathway.

Heterocyclic androstane and estrane d-ring modified steroids: Microwave-assisted synthesis, steroid-converting enzyme inhibition, apoptosis induction, and effects on genes encoding estrogen inactivating enzymes.

d-ring-fused and d-homo lactone compounds in estratriene and androstane series were synthesized using microwave-assisted reaction conditions. Microwave-irradiated synthesis methods were convenient and effective, and provided high yields with short reaction times. Their inhibition of C17,20-lyase and 17ß-hydroxysteroid dehydrogenase type 1 (17ß-HSD1) activities were studied in in vitro enzyme assays. d-ring-fused triazolyl estrone analog 24 showed potent inhibition of NADH-complexed 17ß-HSD1, with a binding affinity similar to that of the substrate estrone; its inhibition against NADPH-complexed 17ß-HSD1 was markedly weaker. Compound 24 also significantly and selectively reduced proliferation of cancer cell lines of gynecological origin. This estrane triazole changed the cell cycle and induced apoptosis of HeLa, SiHa, and MDA-MB-231 cancer cells, measured by both increased subG1 fraction of cells and activation of caspase-independent signaling pathways. A third mode of anti-estrogenic action of 24 saw increased mRNA expression of the SULT1E1 gene in HeLa cells; in contrast, its 3-benzyloxy analog 23 increased mRNA expression of the HSD17B2 gene, thus showing pronounced pro-drug anti-estrogenic activity. Estradiol-derived d-ring triazole compound 24 thus acts at the enzyme, gene expression and cellular levels to decrease the production of active estrogen hormones, demonstrating its pharmacological potential.

Synthesis and evaluation of AKR1C inhibitory properties of A-ring halogenated oestrone derivatives.

Enzymes AKR1C regulate the action of oestrogens, androgens, and progesterone at the pre-receptor level and are also associated with chemo-resistance. The activities of these oestrone halides were investigated on recombinant AKR1C enzymes. The oestrone halides with halogen atoms at both C-2 and C-4 positions (13ß-, 13α-methyl-17-keto halogen derivatives) were the most potent inhibitors of AKR1C1. The lowest IC50 values were for the 13α-epimers 2_2I,4Br and 2_2I,4Cl (IC50, 0.7 µM, 0.8 µM, respectively), both of which selectively inhibited the AKR1C1 isoform. The 13α-methyl-17-keto halogen derivatives 2_2Br and 2_4Cl were the most potent inhibitors of AKR1C2 (IC50, 1.5 µM, 1.8 µM, respectively), with high selectivity for the AKR1C2 isoform. Compound 1_2Cl,4Cl showed the best AKR1C3 inhibition, and it also inhibited AKR1C1 (Ki: AKR1C1, 0.69 µM; AKR1C3, 1.43 µM). These data show that halogenated derivatives of oestrone represent a new class of potent and selective AKR1C inhibitors as lead compounds for further optimisations.

Altered Profile of E1-S Transporters in Endometrial Cancer: Lower Protein Levels of ABCG2 and OSTß and Up-Regulation of SLCO1B3 Expression.

Endometrial cancer (EC) is associated with increased estrogen actions. Locally, estrogens can be formed from estrone-sulphate (E1-S) after cellular uptake by organic anion-transporting polypeptides (OATP) or organic anion transporters (OAT). Efflux of E1-S is enabled by ATP Binding Cassette transporters (ABC) and organic solute transporter (OST)αß. Currently, 19 E1-S transporters are known but their roles in EC are not yet understood. Here, we analysed levels of E1-S transporters in Ishikawa (premenopausal EC), HEC-1-A (postmenopausal EC), HIEEC (control) cell lines, in EC tissue, examined metabolism of steroid precursor E1-S, studied effects of OATPs' inhibition and gene-silencing on E1-S uptake, and assessed associations between transporters and histopathological data. Results revealed enhanced E1-S metabolism in HEC-1-A versus Ishikawa which could be explained by higher levels of OATPs in HEC-1-A versus Ishikawa, especially 6.3-fold up-regulation of OATP1B3 (SLCO1B3), as also confirmed by immunocytochemical staining and gene silencing studies, lower ABCG2 expression and higher levels of sulfatase (STS). In EC versus adjacent control tissue the highest differences were seen for ABCG2 and SLC51B (OSTß) which were 3.0-fold and 2.1-fold down-regulated, respectively. Immunohistochemistry confirmed lower levels of these two transporters in EC versus adjacent control tissue. Further analysis of histopathological data indicated that SLCO1B3 might be important for uptake of E1-S in tumours without lymphovascular invasion where it was 15.6-fold up-regulated as compared to adjacent control tissue. Our results clearly indicate the importance of E1-S transporters in EC pathophysiology and provide a base for further studies towards development of targeted treatment.

N-Phenyl-1,2,3,4-tetrahydroisoquinoline: An Alternative Scaffold for the Design of 17ß-Hydroxysteroid Dehydrogenase 1 Inhibitors.

17ß-Hydroxysteroid dehydrogenases catalyse interconversion at the C17 position between oxidized and reduced forms of steroidal nuclear receptor ligands. The type 1 enzyme, expressed in malignant cells, catalyses reduction of the less-active estrone to estradiol, and inhibitors have therapeutic potential in estrogen-dependent diseases such as breast and ovarian cancers and in endometriosis. Synthetic decoration of the nonsteroidal N-phenyl-1,2,3,4-tetrahydroisoquinoline (THIQ) template was pursued by using Pomeranz-Fritsch-Bobbitt, Pictet-Spengler and Bischler-Napieralski approaches to explore the viability of this scaffold as a steroid mimic. Derivatives were evaluated biologically in vitro as type 1 enzyme inhibitors in a bacterial cell homogenate as source of recombinant protein. Structure-activity relationships are discussed. THIQs possessing a 6-hydroxy group, lipophilic substitutions at the 1- or 4-positions in combination with N-4'-chlorophenyl substitution were most favourable for activity. Of these, one compound had an IC50 of ca. 350 nM as a racemate, testifying to the applicability of this novel approach.

Membrane progesterone receptors ß and γ have potential as prognostic biomarkers of endometrial cancer.

Endometrial cancer (EC) is one of the most common malignancies in women worldwide. EC is linked to chronic exposure to estrogens that is unopposed by protective effects of progesterone. Progesterone modulates gene expression via classical nuclear receptors, and has rapid effects via the less characterized membrane-bound progesterone receptors (mPRs) of the progestin and adipoQ receptor (PAQR) family. The presence of mPRs in EC has not been investigated to date. The aims of this study were to examine PAQR7, PAQR8 and PAQR5, which encode for mPRα, mPRß and mPRγ, respectively, for their expression and localization in EC tissue and adjacent control endometrium. Our results reveal decreased expression of PAQR7 and PAQR8, and unaltered expression of PAQR5 in EC versus control tissue. Expression of PAQR5 was decreased in EC with higher FIGO stage versus stage IA. Immunohistochemistry revealed lower levels of mPRα and mPRß, but higher levels of mPRγ, in EC versus control tissue. There was greater decrease in mPRß levels in tumors with lymphovascular invasion. The analysis of the expression data associates higher PAQR5 mRNA and mPRß protein levels with favorable patient prognosis. Immunohistochemistry showed diverse localizations of mPRs in control and cancer endometrium. In control endometrium, mPRα and mPRß were localized mostly at the cell membranes, while mPRγ was localized in the cytoplasm and/or nucleus. In cancer endometrium, mPRα and mPRß were detected at the cell membrane or in the cytoplasm, or both, while mPRγ was only localized in the cytoplasm. Taken together, these results imply that mPRs are involved in EC pathogenesis through effects on the development or progression of cancer. The potential role of mPRß and mPRγ as prognostic biomarkers needs to be further assessed on a larger number of samples.

The Significance of the Sulfatase Pathway for Local Estrogen Formation in Endometrial Cancer.

Endometrial cancer (EC) is the most common estrogen-dependent gynecological malignancy in the developed World. To investigate the local formation of estradiol (E2), we first measured the concentrations of the steroid precursor androstenedione (A-dione) and the most potent estrogen, E2, and we evaluated the metabolism of A-dione, estrone-sulfate (E1-S), and estrone (E1) in cancerous and adjacent control endometrium. Furthermore, we studied expression of the key genes for estradiol formation via the aromatase and sulfatase pathways. A-dione and E2 were detected in cancerous and adjacent control endometrium. In cancerous endometrium, A-dione was metabolized to testosterone, and no E2 was formed. Both, E1-S and E1 were metabolized to E2, with increased levels of E2 seen in cancerous tissue. There was no significant difference in expression of the key genes of the aromatase (CYP19A1) and the sulfatase (STS, HSD17B1, HSD17B2) pathways in cancerous endometrium compared to adjacent control tissue. The mRNA levels of CYP19A1 and HSD17B1 were low, and HSD17B14, which promotes inactivation of E2, was significantly down-regulated in cancerous endometrium, especially in patients with lymphovascular invasion. At the protein level, there were no differences in the levels of STS and HSD17B2 between cancerous and adjacent control tissue by Western blotting, and immunohistochemistry revealed intense staining for STS and HSD17B2, and weak staining for SULT1E1 and HSD17B1 in cancerous tissue. Our data demonstrate that in cancerous endometrium, E2 is formed from E1-S via the sulfatase pathway, and not from A-dione via the aromatase pathway.

Data on expression of genes involved in estrogen and progesterone action, inflammation and differentiation according to demographic, histopathological and clinical characteristics of endometrial cancer patients.

Endometrial cancer is the sixth most common cancer in women worldwide. It is associated with aberrant actions of steroid hormones, estrogens and progesterone, but also with enhanced inflammation and reduced cellular differentiation. Here, we show data on demographic and histopathological characteristics of 51 patients with endometrial cancer, together with data on correlations between the expression of 38 genes involved in estrogen and progesterone actions, inflammation and differentiation, and demographic characteristics. We also show data on changes in gene expression of these 38 genes according to histopathological and clinical characteristics of these patients. This article includes data referenced in the manuscript entitled ¼STAR and AKR1B10 are down-regulated in high-grade endometrial cancer by Sinreih et al. (in press) [1].

STAR and AKR1B10 are down-regulated in high-grade endometrial cancer.

Endometrial cancer is the most frequent gynecological malignancy in the developed world. The majority of cases are estrogen dependent, and are associated with diminished protective effects of progesterone. Endometrial cancer is also related to enhanced inflammation and decreased differentiation. In our previous studies, we examined the expression of genes involved in estrogen and progesterone actions in inflammation and tumor differentiation, in tissue samples from endometrial cancer and adjacent control endometrium. The aims of the current study were to examine correlations between gene expression and several demographic characteristics, and to evaluate changes in gene expression with regard to histopathological and clinical characteristics of 51 patients. We studied correlations and differences in expression of 38 genes involved in five pathophysiological processes: (i) estrogen-stimulated proliferation; (ii) estrogen-dependent carcinogenesis; (iii) diminished biosynthesis of progesterone: (iv) enhanced formation of progesterone metabolites; and (v) increased inflammation and decreased differentiation. Spearman correlation coefficient analysis shows that expression of PAQR7 correlates with age, expression of SRD5A1, AKR1B1 and AKR1B10 correlate with body mass, while expression of SRD5A1 and AKR1B10 correlate with body mass index. When patients with endometrial cancer were stratified based on menopausal status, histological grade, myometrial invasion, lymphovascular invasion, and FIGO stage, Mann-Whitney U tests revealed significantly decreased expression of STAR (4.4-fold; adjusted p=0.009) and AKR1B10 (9-fold; adjusted p=0.003) in high grade versus low grade tumors. Lower levels of STAR might lead to decreased de-novo steroid hormone synthesis and tumor differentiation, and lower levels of AKR1B10 to diminished elimination of toxic electrophilic carbonyl compounds in high-grade endometrial cancer. These data thus reveal the potential of STAR and AKR1B10 as prognostic biomarkers, which calls for further validation at the protein level.

Pyrithione-based ruthenium complexes as inhibitors of aldo-keto reductase 1C enzymes and anticancer agents.

Four ruthenium complexes of clinically used zinc ionophore pyrithione and its oxygen analog 2-hydroxypyridine N-oxide were prepared and evaluated as inhibitors of enzymes of the aldo-keto reductase subfamily 1C (AKR1C). A kinetic study assisted with docking simulations showed a mixed type of inhibition consisting of a fast reversible and a slow irreversible step in the case of both organometallic compounds 1A and 1B. Both compounds also showed a remarkable selectivity towards AKR1C1 and AKR1C3 which are targets for breast cancer drug design. The organoruthenium complex of ligand pyrithione as well as pyrithione itself also displayed toxicity on the hormone-dependent MCF-7 breast cancer cell line with EC50 values in the low micromolar range.

Combined liquid chromatography-tandem mass spectrometry analysis of progesterone metabolites.

Progesterone has a number of important functions throughout the human body. While the roles of progesterone are well known, the possible actions and implications of progesterone metabolites in different tissues remain to be determined. There is a growing body of evidence that these metabolites are not inactive, but can have significant biological effects, as anesthetics, anxiolytics and anticonvulsants. Furthermore, they can facilitate synthesis of myelin components in the peripheral nervous system, have effects on human pregnancy and onset of labour, and have a neuroprotective role. For a better understanding of the functions of progesterone metabolites, improved analytical methods are essential. We have developed a combined liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for detection and quantification of progesterone and 16 progesterone metabolites that has femtomolar sensitivity and good reproducibility in a single chromatographic run. MS/MS analyses were performed in positive mode and under constant electrospray ionization conditions. To increase the sensitivity, all of the transitions were recorded using the Scheduled MRM algorithm. This LC-MS/MS method requires small sample volumes and minimal sample preparation, and there is no need for derivatization. Here, we show the application of this method for evaluation of progesterone metabolism in the HES endometrial cell line. In HES cells, the metabolism of progesterone proceeds mainly to (20S)-20-hydroxy-pregn-4-ene-3-one, (20S)-20-hydroxy-5α-pregnane-3-one and (20S)-5α-pregnane-3α,20-diol. The investigation of possible biological effects of these metabolites on the endometrium is currently undergoing.

Important roles of the AKR1C2 and SRD5A1 enzymes in progesterone metabolism in endometrial cancer model cell lines.

Endometrial cancer is the most frequently diagnosed gynecological malignancy. It is associated with prolonged exposure to estrogens that is unopposed by progesterone, whereby enhanced metabolism of progesterone may decrease its protective effects, as it can deprive progesterone receptors of their active ligand. Furthermore, the 5α-pregnane metabolites formed can stimulate proliferation and may thus contribute to carcinogenesis. The aims of our study were to: (1) identify and quantify progesterone metabolites formed in the HEC-1A and Ishikawa model cell lines of endometrial cancer; and (2) pinpoint the enzymes involved in progesterone metabolism, and delineate their roles. Progesterone metabolism studies combined with liquid chromatography-tandem mass spectrometry enabled identification and quantification of the metabolites formed in these cells. Further quantitative PCR analysis and small-interfering-RNA-mediated gene silencing identified individual progesterone metabolizing enzymes and their relevant roles. In Ishikawa and HEC-1A cells, progesterone was metabolized mainly to 20α-hydroxy-pregn-4-ene-3-one, 20α-hydroxy-5α-pregnane-3-one, and 5α-pregnane-3α/ß,20α-diol. The major difference between these cell lines was rate of progesterone metabolism, which was faster in HEC-1A cells. In the Ishikawa and HEC-1A cells, expression of AKR1C2 was 110-fold and 6800-fold greater, respectively, than expression of AKR1C1, which suggests that 20-ketosteroid reduction of 5α-pregnanes and 4-pregnenes is catalyzed mainly by AKR1C2. AKR1C1/AKR1C2 gene silencing showed decreased progesterone metabolism in both cell lines, thus further supporting the significant role of AKR1C2. SRD5A1 was also expressed in these cells, and its silencing confirmed that 5α-reduction is catalyzed by 5α-reductase type 1. Silencing of SRD5A1 also had the most pronounced effects, with decreased rate of progesterone metabolism, and consequently higher concentrations of unmetabolized progesterone. Our data confirm that in model cell lines of endometrial cancer, AKR1C2 and SRD5A1 have crucial roles in progesterone metabolism, and may represent novel targets for treatment.

Expression of AKR1B1, AKR1C3 and other genes of prostaglandin F2α biosynthesis and action in ovarian endometriosis tissue and in model cell lines.

Endometriosis is a frequent benign gynecological disease characterized by endometrial tissue outside the uterine cavity. The estimated prevalence in the general population is 6-10%, but this reaches 30-50% in women with infertility and/or pain. As ectopic tissue within the pelvic cavity provokes inflammation, endometriosis is also considered a chronic inflammatory disease, and is characterized by increased peritoneal fluid levels of prostaglandin (PG)E2 and PGF2α. The AKR1B1 and AKR1C3 enzymes act as PG synthases and catalyze reduction of PGH2 to PGF2α, and PGD2 to 9α,11ß-PGF2α, respectively. AKR1B1 and AKR1C3 may thus be associated with increased PGF2α production in endometriosis patients, as supported by our previous report of increased AKR1C1-AKR1C3 mRNA levels in endometriotic tissue, compared to control endometrium. Here, we initially evaluated PGF2α concentrations in peritoneal fluid from endometriosis patients and healthy women. We also examined expression of AKR1B1, AKR1C3 and other genes involved in PGF2α biosynthesis, metabolism, and action in ovarian endometriosis tissue versus healthy endometrium, and in peritoneal endometriosis and control endometrium model cell lines. Compared to controls, increased PGF2α concentrations in peritoneal fluid of patients were supported by endometriotic tissue showing increased AKR1B1 mRNA and protein levels, but unchanged AKR1C3 protein levels. Among genes involved in PGF2α biosynthesis, metabolism and action PLA2G2A, PTGS2/COX-2, ABCC4 and PTGFR were up-regulated, mRNA levels of SLCO2A, PTGDS and HPGDS were unchanged, and genes PLA2G4A and HPGD were down-regulated in diseased tissue. All of these PGF2α-associated genes were also expressed in control endometrial HIEEC epithelial and HIESC stromal cell lines, and in peritoneal endometriosis 12-Z epithelial and 22-B stromal cell lines. Higher expression of PLA2G2A, PTGS2, AKR1B1, AKR1C3 and ABCC4 was seen in 22-B endometriosis cells compared to HIESC control cells. These cell models characterized in this study will enable further investigations into the role of PGF2α in the pathophysiology of endometriosis and the involvement of AKR1B1 and AKR1C3.

Ruthenium complexes as inhibitors of the aldo-keto reductases AKR1C1-1C3.

The human aldo-keto reductases (AKRs) from the 1C subfamily are important targets for the development of new drugs. In this study, we have investigated the possible interactions between the recombinant AKR1C enzymes AKR1C1-AKR1C3 and ruthenium(II) complexes; in particular, we were interested in the potential inhibitory actions. Five novel ruthenium complexes (1a, 1b, 2a, 2b, 2c), two precursor ruthenium compounds (P1, P2), and three ligands (a, b, c) were prepared and included in this study. Two different types of novel ruthenium(II) complexes were synthesized. First, bearing the sulphur macrocycle [9]aneS3, S-bonded dimethylsulphoxide (dmso-S), and an N,N-donor ligand, with the general formula of [Ru([9]aneS3)(dmso)(N,N-ligand)](PF6)2 (1a, 1b), and second, with the general formula of [(η(6)-p-cymene)RuCl(N,N-ligand)]Cl (2a, 2b, 2c). All of these synthesized compounds were characterized by high-resolution NMR spectroscopy, X-ray crystallography (compounds a, b, c, 1a, 1b) and other standard physicochemical methods. To evaluate the potential inhibitory actions of these compounds on the AKR1C enzymes, we followed enzymatically catalyzed oxidation of the substrate 1-acenaphthenol by NAD(+) in the absence and presence of various micromolar concentrations of the individual compounds. Among 10 compounds, one ruthenium complex (2b) and two precursor ruthenium compounds (P1, P2) inhibited all three AKR1C enzymes, and one ruthenium complex (2a) inhibited only AKR1C3. Ligands a, b and c revealed no inhibition of the AKR1C enzymes. All four of the active compounds showed multiple binding with the AKR1C enzymes that was characterized by an initial instantaneous inhibition followed by a slow quasi-irreversible step. To the best of our knowledge, this is the first study that has examined interactions between these AKR1C enzymes and ruthenium(II) complexes.

Altered expression of genes involved in progesterone biosynthesis, metabolism and action in endometrial cancer.

Endometrial cancer (EC) is one of the most common gynecological malignancies worldwide. It is associated with prolonged exposure to estrogens that is unopposed by the protective effects of progesterone, which suggests that altered progesterone biosynthesis, metabolism and actions might be implicated in the development of EC. Our aim was to evaluate these processes through quantitative real-time PCR expression analysis in up to 47 pairs of EC tissue and adjacent control endometrium. First, we examined the expression of genes encoding proteins associated with progesterone biosynthesis: steroidogenic acute regulatory protein (STAR); a side chain cleavage enzyme (CYP11A1); and 3ß-hydroxysteroid dehydrogenase/ketosteroid isomerase (HSD3B). There were 1.9- and 10.0-fold decreased expression of STAR and CYP11A1, respectively, in EC versus adjacent control endometrium, with no significant differences in the expression of HSD3B1 and HSD3B2. Next, we examined expression of genes encoding five progesterone metabolizing enzymes: the 3-keto and 20-ketosteroid reductases (AKR1C1-AKR1C3) and 5α-reductases (SRD5A1 and SRD5A2); and the opposing 20α-hydroxysteroid dehydrogenase (HSD17B2). These genes are expressed in EC and adjacent control endometrium. No statistically significant differences were seen in mRNA levels of AKR1C1, AKR1C2, AKR1C3 and SRD5A1. Expression of HSD17B2 was 3.0-fold increased, and expression of SRD5A2 was 3.7-fold decreased, in EC versus adjacent control endometrium. We also examined mRNA levels of progesterone receptors A and B (PGR), and separately the expression of progesterone receptor B (PR-B). Here we saw 1.8- and 2.0-fold lower mRNA levels of PGR and PR-B, respectively, in EC versus adjacent control endometrium. This down-regulation of STAR, CYP11A1 and PGR in endometrial cancer may lead to decreased progesterone biosynthesis and actions although the effects on progesterone levels should be further studied.

N-Benzoyl anthranilic acid derivatives as selective inhibitors of aldo-keto reductase AKR1C3.

Human aldo-keto reductases AKR1C1-AKR1C3 are involved in the biosynthesis and inactivation of steroid hormones and prostaglandins and thus represent attractive targets for the development of new drugs. We synthesized a series of N-benzoyl anthranilic acid derivatives and tested their inhibitory activity on AKR1C enzymes. Our data show that these derivatives inhibit AKR1C1-AKR1C3 isoforms with low micromolar potency. In addition, five selective inhibitors of AKR1C3 were identified. The most promising inhibitors were compounds 10 and 13, with IC(50) values of 0.31 µM and 0.35 µM for AKR1C3, respectively.

Exploration of the chemical space of novel naphthalene-sulfonamide and anthranilic Acid-based inhibitors of penicillin-binding proteins.

Penicillin-binding proteins are a well established, validated and still a very promising target for the design and development of new antibacterial agents. Based on our previous discovery of several noncovalent small-molecule inhibitor hits for resistant PBPs we decided to additionally explore the chemical space around these compounds. In order to clarify their structure-activity relationships for PBP inhibition two new series of compounds were synthesized, characterized and evaluated biochemically: the derivatives of anthranilic acid and naphthalene-sulfonamide derivatives. The target compounds were tested for their inhibitory activities on three different transpeptidases: PBP2a from methicillin-resistant Staphylococcus aureus (MRSA) strains, PBP5fm from Enterococcus faecium strains, and PBP1b from Streptococcus pneumoniae strains. The most promising results for both of these series of compounds were obtained against the PBP2a enzyme with the IC50 values in the micromolar range. Although these results do not represent a significant breakthrough in the field of noncovalent PBP inhibitors, they do provide useful structure-activity relationship data, and thus a more solid basis for the design of potent and noncovalent inhibitors of resistant PBPs.