Steroid sulfatase:a pivotal player in estrogen synthesis and metabolism

International audienceSteroid 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

SHIP2:structure, function and inhibition

SHIP2 is a phosphatase that acts at the 5-position of phosphatidylinositol 3,4,5-trisphosphate. It is one of several enzymes that catalyse dephosphorylation at the 5-position of phosphoinositides or inositol phosphates. SHIP2 has a confirmed role in opsismodysplasia, a disease of bone development, but also interacts with proteins involved in insulin signalling, cytoskeletal function (thus having an impact on endocytosis, adhesion, proliferation and apoptosis) and immune system function. The structure of three domains (constituting about 38% of the protein) is known. Inhibitors of SHIP2 activity have been designed to interact with the catalytic domain with sub-micromolar IC50 values: these come from a range of structural classes and have been shown to have in vivo effects consistent with SHIP2 inhibition. Much remains unknown about the roles of SHIP2 and possible future directions for research are indicated

Synthesis and in vitro antimicrobial SAR of benzyl and phenyl guanidine and aminoguanidine hydrazone derivatives

A series of benzyl, phenyl guanidine, and aminoguandine hydrazone derivatives was designed and in vitro antibacterial activities against two different bacterial strains (Staphylococcus aureus and Escherichia coli) were determined. Several compounds showed potent inhibitory activity against the bacterial strains evaluated, with minimal inhibitory concentration (MIC) values in the low µg/mL range. Of all guanidine derivatives, 3-[2-chloro-3-(trifluoromethyl)]-benzyloxy derivative 9m showed the best potency with MICs of 0.5 µg/mL (S. aureus) and 1 µg/mL (E. coli), respectively. Several aminoguanidine hydrazone derivatives also showed good overall activity. Compounds 10a, 10j, and 10r–s displayed MICs of 4 µg/mL against both S. aureus and E. coli. In the aminoguanidine hydrazone series, 3-(4-trifluoromethyl)-benzyloxy derivative 10d showed the best potency against S. aureus (MIC 1 µg/mL) but was far less active against E. coli (MIC 16 µg/mL). Compound 9m and the para-substituted derivative 9v also showed promising results against two strains of methicillin-resistant Staphylococcus aureus (MRSA). These results provide new and potent structural leads for further antibiotic optimisation strategies

Synthesis and in vitro antimicrobial SAR of benzyl and phenyl guanidine and aminoguanidine hydrazone derivatives

A series of benzyl, phenyl guanidine and aminoguandine hydrazone derivatives was designed and in vitro antibacterial activities against two different bacterial strains (Staphylococcus aureus and Escherichia coli) were determined. Several compounds showed potent inhibitory activity against the bacterial strains evaluated, with minimal inhibitory concentration (MIC) values in the low μg/mL range. Of all guanidine derivatives, 3-[2-chloro-3-(trifluoromethyl)]-benzyloxy deriva-tive 9m showed the best potency with MICs of 0.5 μg/mL (S. aureus) and 1 μg/mL (E. coli), respec-tively. Several aminoguanidine hydrazone derivatives also showed good overall activity. Com-pounds 10a, 10j and 10r-s displayed MICs of 4 μg/mL against both S. aureus and E. coli. In the ami-noguanidine hydrazone series, 3-(4-trifluoromethyl)-benzyloxy derivative 10d showed the best po-tency against S. aureus (MIC 1 μg/mL), but was far less active against E. coli (MIC 16 μg/mL). Com-pound 9m and the para-substituted derivative 9v also showed promising results against two strains of methicillin-resistant Staphylococcus aureus (MRSA). These results provide new and potent struc-tural leads for further antibiotic optimisation strategies

Crystal structures of type-II inositol polyphosphate 5-phosphatase INPP5B with synthetic inositol polyphosphate surrogates reveal new mechanistic insights for the inositol 5-phosphatase family

The inositol polyphosphate 5-phosphatase INPP5B hydrolyzes the 5-phosphate group from water- and lipid-soluble signaling messengers. Two synthetic benzene and biphenyl polyphosphates (BzP/BiPhPs), simplified surrogates of inositol phosphates and phospholipid headgroups, were identified by thermodynamic studies as potent INPP5B ligands. The X-ray structure of the complex between INPP5B and biphenyl 3,3,4,4,5,5-hexakisphosphate [BiPh(3,3,4,4,5,5)P6, IC50 5.5 μM] was determined at 2.89Å resolution. One inhibitor pole locates in the phospholipid headgroup binding site and the second solvent-exposed ring binds to the His-Tag of another INPP5B molecule, while a molecule of inorganic phosphate is also present in the active site. Benzene 1,2,3-trisphosphate [Bz(1,2,3)P3] [one ring of BiPh(3,3,4,4,5,5)P6] inhibits INPP5B ca 6-fold less potently. Co-crystallization with benzene 1,2,4,5-tetrakisphosphate [Bz(1,2,4,5)P4, IC50 = 6.3 μM] yielded a structure refined at 2.9Å resolution. Conserved residues among the 5-phosphatase family mediate similar interactions with Bz(1,2,4,5)P4 and BiPh(3,3',4,4',5,5')P6 to those with the polar groups present in positions 1,4,5 and 6 on the inositol ring of the substrate. 5-Phosphatase specificity most likely resides in the variable zone located close to the 2- and 3-positions of the inositol ring. We propose that the inorganic phosphate present in the INPP5BBiPh(3,3,4,4,5,5)P6 complex mimics the post-cleavage substrate 5-phosphate released by INPP5B in the catalytic site, allowing elucidation of two new key features in the catalytic mechanism proposed for the family of phosphoinositide 5-phosphatases: first, the involvement of the conserved Arg-451 in the interaction with the 5-phosphate and secondly, identification of the water molecule that initiates 5-phosphate hydrolysis. Our model also has implications for the proposed moving metal mechanism

Fluorination Influences the Bioisostery of Myo‐Inositol Pyrophosphate Analogs

Inositol pyrophosphates (PP−IPs) are densely phosphorylated messenger molecules involved in numerous biological processes. PP−IPs contain one or two pyrophosphate group(s) attached to a phosphorylated myo-inositol ring. 5PP−IP5 is the most abundant PP−IP in human cells. To investigate the function and regulation by PP−IPs in biological contexts, metabolically stable analogs have been developed. Here, we report the synthesis of a new fluorinated phosphoramidite reagent and its application for the synthesis of a difluoromethylene bisphosphonate analog of 5PP−IP5. Subsequently, the properties of all currently reported analogs were benchmarked using a number of biophysical and biochemical methods, including co-crystallization, ITC, kinase activity assays and chromatography. Together, the results showcase how small structural alterations of the analogs can have notable effects on their properties in a biochemical setting and will guide in the choice of the most suitable analog(s) for future investigations.Swiss National Science Foundation http://dx.doi.org/10.13039/501100001711German Academic Exchange Service http://dx.doi.org/10.13039/100021828Wellcome Trust http://dx.doi.org/10.13039/100010269Peer Reviewe

Discovery of novel inhibitors of human 11β-hydroxysteroid dehydrogenase type 1

International audienc

Both D- and L-glucose polyphosphates mimic D-myo-inositol 1,4,5-trisphosphate: new synthetic agonists and partial agonists at the Ins(1,4,5)P3 receptor

Chiral sugar derivatives are potential cyclitol surrogates of the Ca2+-mobilizing intracellular messenger d-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. Six novel polyphosphorylated analogues derived from both d- and l-glucose were synthesized. Binding to Ins(1,4,5)P3 receptors [Ins(1,4,5)P3R] and the ability to release Ca2+ from intracellular stores via type 1 Ins(1,4,5)P3Rs were investigated. β-d-Glucopyranosyl 1,3,4-tris-phosphate, with similar phosphate regiochemistry and stereochemistry to Ins(1,4,5)P3, and α-d-glucopyranosyl 1,3,4-tris-phosphate are full agonists, being equipotent and 23-fold less potent than Ins(1,4,5)P3, respectively, in Ca2+-release assays and similar to Ins(1,4,5)P3 and 15-fold weaker in binding assays. They can be viewed as truncated analogues of adenophostin A and refine understanding of structure-activity relationships for this Ins(1,4,5)P3R agonist. l-Glucose-derived ligands, methyl α-l-glucopyranoside 2,3,6-trisphosphate and methyl α-l-glucopyranoside 2,4,6-trisphosphate, are also active, while their corresponding d-enantiomers, methyl α-d-glucopyranoside 2,3,6-trisphosphate and methyl α-d-glucopyranoside 2,4,6-trisphosphate, are inactive. Interestingly, both l-glucose-derived ligands are partial agonists: they are among the least efficacious agonists of Ins(1,4,5)P3R yet identified, providing new leads for antagonist development

Cyclic adenosine 5′-diphosphate ribose analogs without a southern ribose inhibit ADP-ribosyl cyclase-hydrolase CD38

Cyclic adenosine 5′-diphosphate ribose (cADPR) analogs based on the cyclic inosine 5′-diphosphate ribose (cIDPR) template were synthesized by recently developed stereo- and regioselective <i>N</i>1-ribosylation. Replacing the base <i>N</i>9-ribose with a butyl chain generates inhibitors of cADPR hydrolysis by the human ADP-ribosyl cyclase CD38 catalytic domain (shCD38), illustrating the nonessential nature of the “southern” ribose for binding. Butyl substitution generally improves potency relative to the parent cIDPRs, and 8-amino-<i>N</i>9-butyl-cIDPR is comparable to the best noncovalent CD38 inhibitors to date (IC₅₀ = 3.3 μM). Crystallographic analysis of the shCD38:8-amino-<i>N</i>9-butyl-cIDPR complex to a 2.05 Å resolution unexpectedly reveals an <i>N</i>1-hydrolyzed ligand in the active site, suggesting that it is the <i>N</i>6-imino form of cADPR that is hydrolyzed by CD38. While HPLC studies confirm ligand cleavage at very high protein concentrations, they indicate that hydrolysis does not occur under physiological concentrations. Taken together, these analogs confirm that the “northern” ribose is critical for CD38 activity and inhibition, provide new insight into the mechanism of cADPR hydrolysis by CD38, and may aid future inhibitor design