76 research outputs found
A Small Molecule Inhibitor of PDK1/PLCĪ³1 Interaction Blocks Breast and Melanoma Cancer Cell Invasion
Strong evidence suggests that phospholipase CĪ³1 (PLCĪ³1) is a suitable target to counteract tumourigenesis and metastasis dissemination. We recently identified a novel signalling pathway required for PLCĪ³1 activation which involves formation of a protein complex with 3-phosphoinositide-dependent protein kinase 1 (PDK1). In an effort to define novel strategies to inhibit PLCĪ³1-dependent signals we tested here whether a newly identified and highly specific PDK1 inhibitor, 2-O-benzyl-myo-inositol 1,3,4,5,6-pentakisphosphate (2-O-Bn-InsP5), could affect PDK1/PLCĪ³1 interaction and impair PLCĪ³1-dependent cellular functions in cancer cells. Here, we demonstrate that 2-O-Bn-InsP5 interacts specifically with the pleckstrin homology domain of PDK1 and impairs formation of a PDK1/PLCĪ³1 complex. 2-O-Bn-InsP5 is able to inhibit the epidermal growth factor-induced PLCĪ³1 phosphorylation and activity, ultimately resulting in impaired cancer cell migration and invasion. Importantly, we report that 2-O-Bn-InsP5 inhibits cancer cell dissemination in zebrafish xenotransplants. This work demonstrates that the PDK1/PLCĪ³1 complex is a potential therapeutic target to prevent metastasis and it identifies 2-O-Bn-InsP5 as a leading compound for development of anti-metastatic drugs
SULFATION PATHWAYS: Steroid sulfatase inhibition by aryl sulfamates: clinical progress, mechanism and future prospects
Steroid sulfatase is an emerging drug target for the endocrine therapy of hormone-dependent diseases, catalyzing estrogen sulfate hydrolysis to estrogen. Drug discovery, developing the core aryl O-sulfamate pharmacophore, has led to steroidal and non-steroidal drugs entering numerous clinical trials, with promising results in oncology and womenās health. Steroidal estrogen sulfamate derivatives were the first irreversible active-site-directed inhibitors and one was developed clinically as an oral estradiol pro-drug and for endometriosis applications. This review summarizes work leading to the therapeutic concept of sulfatase inhibition, clinical trials executed to date and new insights into the mechanism of inhibition of steroid sulfatase. To date the non-steroidal sulfatase inhibitor Irosustat has been evaluated clinically in breast cancer, alone and in combination, in endometrial cancer and in prostate cancer. The versatile core pharmacophore both imbues attractive pharmaceutical properties and functions via three distinct mechanisms of action, as a pro-drug, an enzyme active site-modifying motif, likely through direct sulfamoyl group transfer, and as a structural component augmenting activity, for example by enhancing interactions at the colchicine binding site of tubulin. Preliminary new structural data on the Pseudomonas aeruginosa arylsulfatase enzyme suggest two possible sulfamate-based adducts with active site formylglycine as candidates for the inhibition end product via sulfamoyl group or sulfonylamine transfer, and a speculative choice is suggested. The clinical status of sulfatase inhibition is surveyed and how it might develop in the future.
Also discussed are dual-targeting approaches, development of 2-substituted steroidal sulfamates and nonsteroidal derivatives as multi-targeting agents for hormone-independent tumours with other emerging directions
SULFATION PATHWAYS: Steroid sulphatase inhibition via aryl sulphamates: clinical progress, mechanism and future prospects
Steroid sulphatase is an emerging drug target for the endocrine therapy of hormone-dependent diseases, catalysing oestrogen sulphate hydrolysis to oestrogen. Drug discovery, developing the core aryl O-sulphamate pharmacophore, has led to steroidal and non-steroidal drugs entering numerous clinical trials, with promising results in oncology and womenās health. Steroidal oestrogen sulphamate derivatives were the first irreversible active-site-directed inhibitors and one was developed clinically as an oral oestradiol pro-drug and for endometriosis applications. This review summarizes work leading to the therapeutic concept of sulphatase inhibition, clinical trials executed to date and new insights into the mechanism of inhibition of steroid sulphatase. To date, the non-steroidal sulphatase inhibitor Irosustat has been evaluated clinically in breast cancer, alone and in combination, in endometrial cancer and in prostate cancer. The versatile core pharmacophore both imbues attractive pharmaceutical properties and functions via three distinct mechanisms of action, as a pro-drug, an enzyme active-site-modifying motif, likely through direct sulphamoyl group transfer, and as a structural component augmenting activity, for example by enhancing interactions at the colchicine binding site of tubulin. Preliminary new structural data on the Pseudomonas aeruginosa arylsulphatase enzyme suggest two possible sulphamate-based adducts with the active site formylglycine as candidates for the inhibition end product via sulphamoyl or sulphonylamine transfer, and a speculative choice is suggested. The clinical status of sulphatase inhibition is surveyed and how it might develop in the future. Also discussed are dual-targeting approaches, development of 2-substituted steroidal sulphamates and non-steroidal derivatives as multi-targeting agents for hormone-independent tumours, with other emerging directions
SULFATION PATHWAYS: Steroid sulfatase inhibition by aryl sulfamates: clinical progress, mechanism and future prospects
Steroid sulfatase is an emerging drug target for the endocrine therapy of hormone-dependent diseases, catalyzing estrogen sulfate hydrolysis to estrogen. Drug discovery, developing the core aryl O-sulfamate pharmacophore, has led to steroidal and non-steroidal drugs entering numerous clinical trials, with promising results in oncology and womenās health. Steroidal estrogen sulfamate derivatives were the first irreversible active-site-directed inhibitors and one was developed clinically as an oral estradiol pro-drug and for endometriosis applications. This review summarizes work leading to the therapeutic concept of sulfatase inhibition, clinical trials executed to date and new insights into the mechanism of inhibition of steroid sulfatase. To date the non-steroidal sulfatase inhibitor Irosustat has been evaluated clinically in breast cancer, alone and in combination, in endometrial cancer and in prostate cancer. The versatile core pharmacophore both imbues attractive pharmaceutical properties and functions via three distinct mechanisms of action, as a pro-drug, an enzyme active site-modifying motif, likely through direct sulfamoyl group transfer, and as a structural component augmenting activity, for example by enhancing interactions at the colchicine binding site of tubulin. Preliminary new structural data on the Pseudomonas aeruginosa arylsulfatase enzyme suggest two possible sulfamate-based adducts with active site formylglycine as candidates for the inhibition end product via sulfamoyl group or sulfonylamine transfer, and a speculative choice is suggested. The clinical status of sulfatase inhibition is surveyed and how it might develop in the future. Also discussed are dual-targeting approaches, development of 2-substituted steroidal sulfamates and nonsteroidal derivatives as multi-targeting agents for hormone-independent tumours with other emerging directions
Accessing simply-substituted 4-hydroxytetrahydroisoquinolines via Pomeranz-Fritsch-Bobbitt reaction with non-activated and moderately-activated systems
Background 1,2,3,4-Tetrahydroisoquinolines (THIQs) are common motifs in alkaloids and in medicinal chemistry. Synthetic access to THIQs via the Pomeranz-Fritsch-Bobbit (PFB) methodology using mineral acids for deactivated, electron poor aromatic systems, is scarcely represented in the literature. Here, the factors controlling the regiochemical outcome of cyclization are evaluated. Results A double reductive alkylation was telescoped into a one-pot reaction delivering good to excellent yields of desired aminoacetals for cyclization. Cyclization of activated systems proceeded smoothly under standard PFB conditions, but for non-activated systems use of HClO4 alone was effective. When cyclization was possible in both para- and ortho-positions to the substituent, 7-substituted derivatives formed with significant amounts of 5-substituted by-product. The formation of the 4-hydroxy THIQs vs. the 4-methoxy THIQ products could be controlled through modification of the reaction concentration. In addition, while a highly-activated system exclusively cyclized to the indole, this seems generally highly disfavored. When competition between 6- and 7-ring formation was investigated in non-activated systems, 5,7,8,13-tetrahydro-6,13-methanodibenzo[c,f]azonine was exclusively obtained. Furthermore, selective ring closure in the para-position could be achieved under standard PFB conditions, while a double ring closure could be obtained utilizing HClO4. Conclusions Reactivity differences in aminoacetal precursors can be employed to control cyclization using PFB methodology. It is now possible to select confidently the right conditions for synthesis of N-aryl-4-hydroxy-1,2,3,4-tetrahydroisoquinolines.</p
Accessing simply-substituted 4-hydroxytetrahydroisoquinolines via Pomeranz-Fritsch-Bobbitt reaction with non-activated and moderately-activated systems
Background
1,2,3,4-Tetrahydroisoquinolines (THIQs) are common motifs in alkaloids and in medicinal chemistry. Synthetic access to THIQs via the Pomeranz-Fritsch-Bobbit (PFB) methodology using mineral acids for deactivated, electron poor aromatic systems, is scarcely represented in the literature. Here, the factors controlling the regiochemical outcome of cyclization are evaluated.
Results
A double reductive alkylation was telescoped into a one-pot reaction delivering good to excellent yields of desired aminoacetals for cyclization. Cyclization of activated systems proceeded smoothly under standard PFB conditions, but for non-activated systems use of HClO4 alone was effective. When cyclization was possible in both para- and ortho-positions to the substituent, 7-substituted derivatives formed with significant amounts of 5-substituted by-product. The formation of the 4-hydroxy THIQs vs. the 4-methoxy THIQ products could be controlled through modification of the reaction concentration. In addition, while a highly-activated system exclusively cyclized to the indole, this seems generally highly disfavored. When competition between 6- and 7-ring formation was investigated in non-activated systems, 5,7,8,13-tetrahydro-6,13-methanodibenzo[c,f]azonine was exclusively obtained. Furthermore, selective ring closure in the para-position could be achieved under standard PFB conditions, while a double ring closure could be obtained utilizing HClO4.
Conclusions
Reactivity differences in aminoacetal precursors can be employed to control cyclization using PFB methodology. It is now possible to select confidently the right conditions for synthesis of N-aryl-4-hydroxy-1,2,3,4-tetrahydroisoquinolines.</p
Synthetic cADPR analogues may form only one of two possible conformational diastereoisomers
Cyclic adenosine 5ā²-diphosphate ribose (cADPR) is an emerging Ca2+
-mobilising second messenger. cADPR
analogues have been generated as chemical biology tools via both chemo-enzymatic and total synthetic routes.
Both routes rely on the cyclisation of a linear precursor to close an 18-membered macrocyclic ring. We show
here that, after cyclisation, there are two possible macrocyclic product conformers that may be formed,
depending on whether cyclisation occurs to the ārightā or the āleftā of the adenine base (as viewed along the
H-8āC-8 base axis). Molecular modelling demonstrates that these two conformers are distinct and cannot
interconvert. The two conformers would present a different spatial layout of binding partners to the cADPR
receptor/binding site. For chemo-enzymatically generated analogues Aplysia californica ADP-ribosyl cyclase
acts as a template to generate solely the āright-handedā conformer and this corresponds to that of the natural
messenger, as originally explored using crystallography. However, for a total synthetic analogue it is
theoretically possible to generate either product, or a mixture, from a given linear precursor. Cyclisation on
either face of the adenine base is broadly illustrated by the first chemical synthesis of the two enantiomers of
a āsouthernā ribose-simplified cIDPR analogue 8-Br-N9-butyl-cIDPR, a cADPR analogue containing only
one chiral sugar in the ānorthernā ribose, i.e. 8-Br-D- and its mirror image 8-Br-L-N9-butyl-cIDPR. By
replacing the D-ribose with the unnatural L-ribose sugar, cyclisation of the linear precursor with
pyrophosphate closure generates a cyclised product spectroscopically identical, but displaying equal and
opposite specific rotation. These findings have implications for cADPR analogue design, synthesis and
activity
Cellular internalisation of an inositol phosphate visualised by using fluorescent InsP5
When applied extracellularly, myo-inositol hexakisphosphate (InsP 6) and myo-inositol pentakisphosphate (InsP5) can inhibit the growth and proliferation of tumour cells. There is debate about whether these effects result from interactions of InsP6 and InsP5 with intracellular or extracellular targets. We synthesised FAM-InsP 5, a fluorescent conjugate of InsP5 that allows direct visualisation of its interaction with cells. FAM-InsP5 was internalised by H1229 tumour cells, a finding that supports earlier reports that externally applied inositol phosphates can - perhaps surprisingly - enter into cells. Close examination of the process of FAM-InsP5 uptake suggests a mechanism of non-receptor-mediated endocytosis, which is blocked at 4 Ā°C and probably involves interaction of the ligand with the glycocalyx. However, our results are difficult to reconcile with antiproliferative mechanisms that require direct interactions of externally applied InsP5 or InsP 6 with cytosolic proteins, because internalised FAM-InsP5 appears in lysosomes and apparently does not enter the cytoplasm. Studies using FAM-InsP5 are less difficult and time-consuming than experiments using InsP5 or InsP6, a factor that allowed us to analyse cellular uptake across a range of human cell types, identifying strong cell-specific differences. Copyright Ā© 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim
Different substrate specificities of the two ADPR binding sites in TRPM2 channels of Nematostella vectensis and the role of IDPR
NvTRPM2 (Nematostella vectensis Transient Receptor Potential Melastatin 2), the species variant of the human apoptosis-related cation channel hTRPM2, is gated by ADP-ribose (ADPR) independently of the C-terminal NUDT9H domain that mediates ADPR-directed gating in hTRPM2. The decisive binding site in NvTRPM2 is likely to be identical with the N-terminal ADPR binding pocket in zebra fish DrTRPM2. Our aim was a characterization of this binding site in NvTRPM2 with respect to its substrate specificity, in comparison to the classical ADPR interaction site within NUDT9H that is highly homologous in hTRPM2 and NvTRPM2, although only in NvTRPM2, catalytic (ADPRase) activity is conserved. With various ADPR analogues, key differences of the two sites were identified. Particularly, two reported antagonists on hTRPM2 were agonists on NvTRPM2. Moreover, IDP-ribose (IDPR) induced currents both in hTRPM2 and NvTRPM2 but not in NvTRPM2 mutants in which NUDT9H was absent. Thus, IDPR acts on NUDT9H rather than N-terminally, revealing a regulatory function of NUDT9H in NvTRPM2 opposed to that in hTRPM2. We propose that IDPR competitively inhibits the ADPRase function of NUDT9H and evokes ADPR accumulation. The findings provide important insights into the structure-function relationship of NvTRPM2 and will allow further characterization of the novel ADPR interaction site
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