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Biomedical subjects

Michael J Reed

Publications and source records attributed to Michael J Reed.

At least 37 records · Page 2Linked to original sources
PubMed2004

The role of steroid sulphatase in regulating the oestrogenicity of oestrogen sulphamates.

Oestrogen sulphamates have increased systemic, but reduced hepatic oestrogenicity which results from their sequestration and transport through the liver by red blood cells. Oestrogen sulphamates act as prodrugs for the release of natural oestrogens but, as yet, there is little information as to how the sulphamoyl moiety is cleaved from the steroid nucleus. In the present investigation we have used the potent steroid sulphatase (STS) inhibitor, 667 COUMATE, to explore the possibility that STS might be responsible for the hydrolysis of oestrogen sulphamates. Administration of oestrone sulphamate (10 microg/day, s.c., for 5 days) to ovariectomised rats resulted in a 3.5-fold increase in the uterine weights of treated animals. Co-administration of oestrone sulphamate and 667 COUMATE (2 mg/kg) completely blocked STS activity in treated animals and completely abrogated the ability of oestrone sulphamate to stimulate uterine growth. In vitro studies, using [(3)H]oestrone sulphamate or [(3)H]oestrone, revealed that the uptake of the sulphamate derivative (95.9+/-2.4%) by red blood cells was considerably higher than that for the non-sulphamoylated oestrogen (25.1+/-1.9%). Results from these studies demonstrate convincingly that STS is the enzyme responsible for the removal of the sulphamoyl group from oestrogen sulphamates. This enzyme therefore has a crucial role in regulating the oestrogenicity associated with this class of drug.

Animals↗
PubMed2004

Novel 18beta-glycyrrhetinic acid analogues as potent and selective inhibitors of 11beta-hydroxysteroid dehydrogenases.

Extensive structural modifications to the 18beta-glycyrrhetinic acid template are described and their effects on the SAR of the 11beta-hydroxysteroid dehydrogenase isozymes type 1 and 2 from the rat are investigated. Isoform selective inhibitors have been discovered and compound 7 N-(2-hydroxyethyl)-3beta-hydroxy-11-oxo-18beta-olean-12-en-30-oic acid amide is highlighted as a very potent selective inhibitor of 11beta-hydroxysteroid dehydrogenase 2 with an IC(50) = 4pM.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2004

A novel 18 beta-glycyrrhetinic acid analogue as a potent and selective inhibitor of 11 beta-hydroxysteroid dehydrogenase 2.

Using 18beta-glycyrrhetinic acid as a template, the synthesis of a series of secondary amides at the 30-position is described and the effects of these modifications on the SAR of the 11beta-hydroxysteroid dehydrogenase isozymes type 1 and 2 from the rat are investigated. An isoform selective inhibitor has been discovered and compound 5, N-(2-hydroxyethyl)-3beta-hydroxy-11-oxo-18beta-olean-12-en-30-oic acid amide, is highlighted as a very potent and selective inhibitor of 11beta-hydroxysteroid dehydrogenase 2 with an IC(50)=4 pM.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2004

2-Alkylsulfanyl estrogen derivatives: synthesis of a novel class of multi-targeted anti-tumour agents.

A flexible, direct, high yielding synthesis of 2-alkylsulfanyl estrogens from estrone has been developed. 2-Methylsulfanyl estradiol (2-MeSE2) 7 displays a similar anti-proliferative activity to the established 2-methoxyestradiol (2-MeOE2) 1, whilst its 3-O-sulfamate derivative (2-MeSE2MATE) 9 exhibits greatly enhanced anti-proliferative activity, combined with significant inhibition of steroid sulfatase, an enzyme target for the treatment of hormone-dependent tumours.

Antineoplastic Agents↗
PubMed2004

Synthesis, in vitro and in vivo activity of benzophenone-based inhibitors of steroid sulfatase.

Steroid sulfatase (STS) is an important new therapeutic target in oncology. Attempts to design nonsteroidal STS inhibitors, because of the oestrogenicity of the original lead oestrone 3-O-sulfamate in rodents, have led to the discovery of benzophenone-4,4'-O,O-bis-sulfamate (BENZOMATE, 3). The nonfused bicyclic BENZOMATE is a highly potent STS inhibitor in vitro, inhibiting STS activity in intact MCF-7 breast cancer cells by > 70% at 0.1 microM and in placental microsomes by > 98% at 10 microM. When MCF-7 cells were pre-treated with 3 at 1 microM and then washed to remove unbound inhibitor, the initial 94% inhibition was reduced to 89% suggesting that 3, like other sulfamate-based STS inhibitors, inhibits the enzyme irreversibly. This agent also inhibits rat liver STS activity by 84% and 93% respectively 24 h after a single dose of 1 or 10 mg/kg, demonstrating that BENZOMATE possesses similar in vivo potency to the established potent nonsteroidal inhibitor 667COUMATE. Several modifications were made to BENZOMATE structurally and effects on in vitro activity were examined. These structure-activity relationship studies show that its carbonyl and bis-sulfamate groups are pivotal for activity, although conformational flexibility is not required. Two rigid anthraquinone-based sulfamate derivatives however showed inhibitory activity significantly better than BENZOMATE in the MCF-7 cell assay. BENZOMATE and related analogues therefore represent an important class of non-steroidal STS inhibitor and lead compounds for future drug design.

Animals↗
PubMed2004

2-difluoromethyloestrone 3-O-sulphamate, a highly potent steroid sulphatase inhibitor.

Steroid sulphatase is a target enzyme of growing therapeutic importance. The synthesis and in vitro biological evaluation of three novel 2-substituted analogues of oestrone 3-O-sulphamate (EMATE), an established steroid sulphatase inhibitor, are described. One inhibitor, 2-difluoromethyloestrone 3-O-sulphamate (6), was found to have an IC50 of 100 pM and be some 90-fold more potent than EMATE in inhibiting steroid sulphatase activity in a placental microsomal preparation, rendering this agent the most potent steroidal STS inhibitor in vitro reported to date. Lowering of the pKa value of the leaving parent steroid phenol by the 2-difluoromethyl group during irreversible enzyme sulphamoylation most likely facilitates the potent inactivation of steroid sulphatase by (6). However, our preliminary molecular docking studies using the X-ray crystal structure of steroid sulphatase suggest that F.......H interactions between the 2-difluoromethyl group of (6) and hydrogen bond donor residues lining the catalytic site of STS might also contribute to the high potency observed for (6).

Binding Sites↗
PubMed2004

Inhibition of in vitro angiogenesis by 2-methoxy- and 2-ethyl-estrogen sulfamates.

Sulfamoylation of 2-methoxyestrone (2-MeOE1) was shown previously to enhance its potency as an anti-proliferative agent against breast cancer cells. We have examined the ability of a series of 2-methoxyestradiol (2-MeOE2) and 2-ethylestradiol (2-EtE2) sulfamates to inhibit angiogenesis in vitro. 2-MeOE2 bis-sulfamate and 2-EtE2 sulfamate were potent inhibitors of human umbilical vein endothelial cell (HUVEC) proliferation with IC(50) values of 0.05 microM and 0.01 microM, respectively. A novel co-culture system, in which endothelial cells were cultured in a matrix of human dermal fibroblasts, was also used to assess the anti-angiogenic potential of these drugs. In this system endothelial cells proliferate and migrate through the culture matrix to form tubule structures. Whereas 2-MeOE2 (1.0 microM) caused a small reduction in tubule formation, both 2-MeOE2 bis-sulfamate (0.1 microM) and 2-EtE2 sulfamate (0.1 microM) almost completely abolished tubule formation. 2-MeOE2 bis-sulfamate and 2-EtE2 sulfamate both induced BCL-2 phosphorylation, p53 protein expression and apoptosis in HUVECs. Microarray analysis of a limited number of genes known to be involved in the angiogenic process did not show any gross changes in cells treated with the 2-substituted estrogens. The sulfamoylated derivatives of 2-MeOE2 and 2-EtE2 are potent inhibitors of in vitro angiogenesis and both compounds should have therapeutic potential.

Angiogenesis Inhibitors↗
PubMed2003

First dual aromatase-steroid sulfatase inhibitors.

Aromatase inhibitors in clinical use block the biosynthesis of estrogens. Hydrolysis of estrone 3-sulfate by steroid sulfatase is an important additional source of tumor estrogen, and blockade of both enzymes should provide a more effective endocrine therapy. Sulfamoylated derivatives of the aromatase inhibitor YM511 inhibited sulfatase and aromatase in JEG-3 cells with respective IC(50) values of 20-227 and 0.82-100 nM (cf. letrozole, 0.89 nM). One dual inhibitor was potent against both enzymes in vivo, validating the concept.

Animals↗
PubMed2003

D-ring modified estrone derivatives as novel potent inhibitors of steroid sulfatase.

A series of novel D-ring modified derivatives of estrone was synthesized and tested as inhibitors of steroid sulfatase (STS). The steroidal D-ring was cleaved via an iodoform reaction and thermal condensation of the resulting marrianolic acid derivative gave 16,17-seco-estra-1,3,5(10)-triene-16,17-imide derivatives, where a piperidinedione moiety is in place of the D-ring. This synthetic approach was found to give a higher overall yield than the literature method of Beckmann rearrangement. A range of alkyl side chains have been introduced on the nitrogen atom of the imido-ring and the corresponding 3-O-sulfamates synthesized. The new D-ring modified estrone derivatives bearing a propyl (39) and a 1-pyridin-3-ylmethyl (46) moiety had IC(50) values of 1 nM when tested in placental microsomes for the inhibition of STS. These compounds are therefore up to 18-fold more potent than EMATE, the very first highly potent irreversible steroidal STS inhibitor.

Crystallography, X-Ray↗
PubMed2003

The effects of 2-substituted oestrogen sulphamates on the growth of prostate and ovarian cancer cells.

The human endogenous metabolite 2-methoxyoestradiol (2-MeOE2) has been shown to inhibit the proliferation of breast cancer cells. We have previously shown that sulphamoylation of a series of 2-substituted oestrogens greatly enhances their ability to inhibit breast cancer cell proliferation and induce apoptosis. In this study, we have investigated the ability of a number of 2-substituted oestrogens and their sulphamoylated derivatives to inhibit the proliferation of two prostate cancer cell lines, an ovarian cancer cell line and its drug-resistant derivatives. 2-Methoxyoestrone, 2-ethyloestrone and 2-ethyloestradiol had little effect on the growth of the cell lines tested (IC(50)>10 microM). 2-MeOE2 did inhibit the growth of the cells (IC(50)<10 microM), but to a lesser extent than any of the sulphamoylated derivatives tested (IC(50)<1.0 microM). Cells treated with the sulphamoylated derivatives became detached and rounded, displaying a characteristic apoptotic appearance. FACS analysis revealed induced G(2)/M cell cycle arrest. Treatment of cells and subsequent drug removal indicated that the effects of the drugs on the cells were irreversible. Immunoblot analysis indicated that apoptosis may be induced by phosphorylation of BCL-2. From these studies, 2-substituted oestrogen sulphamates are emerging as a potent new class of drug that may be effective against AR+/AR- prostate and ovarian tumours, and against tumours that are resistant to conventional chemotherapeutic regimens.

2-Methoxyestradiol↗
PubMed2003

Development of a sensitive high-performance liquid chromatography method for the detection of 667 COUMATE in vivo.

Steroid sulphatase inhibitors which decrease or prevent the biosynthesis of oestrogens, potentially have an important role in the treatment of breast cancer in postmenopausal women. The non-steroidal sulphatase inhibitor 667 COUMATE has been shown to be active both in vitro and in vivo. The pharmacokinetics of this drug have not been investigated. In preparation for the clinical evaluation of this agent, a sensitive and robust reversed phase high-performance liquid chromatography (HPLC) method was developed for the detection of 667 COUMATE in biological fluids. The sulphatase inhibitor was extracted from plasma with diethyl ether and separated from putative metabolites and endogenous plasma components with a C3-phenyl column. Using this method an extraction efficiency of 76+/-5% and a limit of detection of less than 0.1 ng/ml was achieved. The stability of this agent was investigated under different pH conditions and during storage in plasma at room temperature or -20 degrees C. 667 COUMATE was found to be stable when stored in acidified plasma (pH 4.5) at -20 degrees C. In conclusion, the HPLC method developed is a reproducible and sensitive assay that will enable quantitation of the potent non-steroidal sulphatase inhibitor 667 COUMATE in biological fluids in the forthcoming Phase I clinical trial.

Chemistry, Clinical↗
PubMed2003

Novel D-ring modified steroid derivatives as potent, non-estrogenic, steroid sulfatase inhibitors with in vivo activity.

In pursuit of novel steroid sulfatase (STS) inhibitors devoid of estrogenicity, several D-ring modified steroid derivatives were synthesised. In vitro evaluation of the compounds identified two highly potent inhibitors, 4a and 4b, which were 18 times more active than estrone-3-O-sulfamate (EMATE), both having IC(50) values of ca. 1nM. These 16,17-seco-estra-1,3,5(10)-triene-16,17-imide derivatives were synthesised from estrone, via the intermediate 1, which was easily alkylated, deprotected and sulfamoylated affording the final compounds in high yields. In order to assess their biological profile, the selected inhibitors were tested for their in vivo inhibitory potency and estrogenicity in ovariectomised rats. After an oral dose of 10mg/kg per day for 5 days, 4a and 4b were found to inhibit rat liver steroid sulfatase by 99%. They were also devoid of estrogenic activity in the uterine weight gain assay, indicating that these two leads have therapeutic potential for the treatment of hormone-dependent breast cancer.

Animals↗
PubMed2003

Inhibition of MCF-7 breast cancer cell proliferation and in vivo steroid sulphatase activity by 2-methoxyoestradiol-bis-sulphamate.

The endogenous oestrogen metabolite, 2-methoxyoestradiol (2-MeOE2) inhibits the growth of breast cancer cells and is also a potent anti-angiogenic agent. We have previously shown that the 3-sulphamoylated derivatives of 2-methoxyoestrogens are more potent than the non-sulphamoylated compounds. In this study, we have compared the abilities of 2-methoxyoestradiol-bis-sulphamate (2-MeOE2bisMATE) and 2-MeOE2 to inhibit the growth of MCF-7 breast cancer cells. Both compounds inhibited cell growth with the IC(50) for 2-MeOE2bisMATE (0.4 microM) being six-fold lower than that for 2-MeOE2 (2.5 microM). Oestrogen sulphamates are potent inhibitors of steroid sulphatase (STS) activity. 2-MeOE2bisMATE was found to retain its STS inhibitory activity and in a placental microsome assay system it was equipotent with oestrone-3-O-sulphamate (EMATE). An in vivo study was also carried out to compare the potency of 2-MeOE2bisMATE with that of EMATE and the non-steroidal STS inhibitor, 667 coumarin sulphamate (667 COUMATE). After a single oral dose (10mg/kg) some recovery of STS activity was detected by day 3 (10%) with activity partially restored (55%) by day 7 after administration of 667 COUMATE. For the other two steroidal compounds, STS activity remained almost completely inactivated for up to 5 days with complete restoration of activity occurring by day 15. The anti-proliferative and STS inhibitory properties of 2-MeOE2bisMATE suggest that it has considerable potential for development as a novel anti-cancer drug.

2-Methoxyestradiol↗
PubMed2002

Estrone 3-sulfate mimics, inhibitors of estrone sulfatase activity: homology model construction and docking studies.

Steroid sulfatase (STS) is a new target for the endocrine therapy of breast cancer. To ascertain some of the requirements for inhibition of estrone sulfatase activity, a number of novel analogues of estrone 3-O-sulfate possessing sulfate surrogates were synthesized and evaluated as inhibitors of estrone sulfatase (STS) in comparison to a lead inhibitor, estrone-3-O-methylthiophosphonate (E1-3-MTP). Using a selective enzyme digestion, one of the diastereoisomers of this compound, (R(p))-E1-3-MTP, could be prepared and evaluated. From structure-activity studies, we show that chirality at the phosphorus atom, hydrophobicity, basicity, size, and charge all influence the ability of a compound to inhibit estrone sulfatase activity. Of these, hydrophobicity seems to be the most important since simple, active nonsteroidal inhibitors, based on 5,6,7,8-tetrahydronaphth-2-ol (THN), can be prepared, provided that they are lipophilic enough to partition into a nonpolar environment. Also, a negatively charged group is favorable for optimal binding, although it appears that the presence of a potentially cleavable group can compensate for lack of charge in certain cases. A homology model of STS has been constructed from the STS sequence, and molecular docking studies of inhibitors have been performed to broaden the understanding of enzyme/inhibitor interactions. This model clearly shows the positions of the key amino acid residues His136, His290, Lys134, and Lys368 in the putative catalytic region of the formylglycine at position 75, with residues Asp35, Asp36, Asp342, and Gln343 as ligands in the coordination sphere of the magnesium ion. Docking studies using the substrate and estrone-3-sulfate mimics that are active inhibitors indicate they are positioned in the area of proposed catalysis, confirming the predictive power of the model.

Animals↗
PubMed2002

The role of cytokines in regulating estrogen synthesis: implications for the etiology of breast cancer.

Cytokines, such as IL-6 and tumor necrosis factor (TNF)-alpha, have an important role in regulating estrogen synthesis in peripheral tissues, including normal and malignant breast tissues. The activities of the aromatase, estradiol 17beta-hydroxysteroid dehydrogenase and estrone sulfatase are all increased by IL-6 and TNF-alpha. Prostaglandin E2 may also be an important regulator of aromatase activity in breast tumors. Macrophages and lymphocytes, which invade many breast tumors, are thought to be an important source of factors that can stimulate estrogen synthesis in malignant breast tissues. The co-ordinated stimulation of the activities of the enzymes that are involved in estrogen synthesis offers an explanation for the high concentrations of estrogens that are present in breast tumors.

Aromatase↗