Spelling suggestions: "subject:"polysialic acid"" "subject:"polysilic acid""
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Design, synthesis and biological evaluation of inhibitors of polysialyltransferases PST and STX : design, synthesis and biological evaluation of a range of N-modified mannosamines, sialic acids and analogues from in silico screening as inhibitors of PolySia-NCAM biosynthesis with anti-migration activitySpringett, Bradley Ross January 2013 (has links)
Polysialylated NCAM (polySia-NCAM) is re-expressed in a number of tumours, including small cell lung carcinoma and neuroblastoma and is strongly associated with aggressive, invasive and metastatic tumours in the clinic. SiRNA knockdown of the polysialyltransferases (polySTs), the enzymes responsible for polysialylation of neural cell adhesion molecule (NCAM), has been shown to abolish cell migration. PolySia-NCAM is thus a highly attractive novel therapeutic target. A library of potential polyST inhibitors has been synthesised, using substrate-based design and computational chemistry. Compounds synthesised include N-acylmannosamine analogues, thio-linked CMP-sialic acid analogues, N-acyl modified sialic acids and compounds incorporating elements of both approaches. Novel methodology development in the synthesis of many of the compounds is described, notably a novel route to N-acyl sialosides. In addition, compounds identified from in silico screening were considered. Routes to synthesis and isolation of analogues of biologically active compounds are described. Using an enzyme assay, compounds were evaluated for their ability to reduce polySia synthesis through polyST inhibition. Effects of agents on polySia expression in cells, and the ability of compounds to reduce cell migration in vitro was studied using a wound healing ‘scratch assay’. The data from these experiments revealed a number of potent modulators of polySia assembly and their efficacy in reducing cell migration, as well as the limits of the biosynthetic pathway to accept unnatural sialic acid precursors. This is the first example of polyST inhibition modulating tumour cell migration, and points to the potential of the polysialyltransferases as a therapeutic target in metastatic tumours.
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Pharmacological evaluation of novel polysialyltransferase inhibitors as anti-metastatic agents and development of analytical methods for assessment of polysialylation inhibition : in vitro assessment of the effects of novel polysialyltransferase inhibitors on tumour cell function and development of quantitative HPLC-based methods for evaluation of novel polysialyltransferase inhibitorsElkashef, Sara M. January 2016 (has links)
Polysialic acid (polySia) is a carbohydrate polymer highly expressed during embryonic development but rarely expressed during postnatal development. Two polysialyltransferase (polyST) enzymes are responsible for the synthesis of polySia: ST8SiaII and ST8SiaIV. During oncogenesis polySia is re-expressed and it modulates cell-cell and cell-matrix adhesion, migration, invasion and metastasis. PolySia expression is strongly associated with poor clinical prognosis and correlates with aggressive and invasive disease in neuroblastoma and many other tumours. PolyST inhibition thus presents a novel, selective and largely unexplored therapeutic opportunity to reduce tumour dissemination. Progress towards development of polyST inhibitors has been limited by lack of an efficient technique for quantitative assessment of enzyme activity. We have validated a highly sensitive cell-based and cell-free high throughput HPLC-based inhibition assays. Using isogenic cell lines (C6-STX: polySia+/ST8SiaII+ and C6-WT: polySia-/ST8SiaII-) and naturally polySia expressing human neuroblastoma cells (SH-SY5Y), a set of ST8SiaII inhibitors designed and synthesised in house were evaluated for their ability to reduce polySia expression and to modulate cell migration in vitro. We have identified CMP-sialic acid precursors, including ICT-3176, which reduced polySia expression and tumour cell migration by up to 70%. These effects were only found in cell lines expressing ST8SiaII and polySia. Furthermore, we have investigated the possible additive anti-migratory effect of combining polyST inhibition with the inhibition of certain signalling pathways that have been previously suggested to be modulated by polySia expression. Out of these combinations it was found that combining ST8SiaII and C-MET/ALK inhibition had a synergistic effect on inhibiting cancer cell migration. Additionally, the effect of polySia expression on cancer cell behaviour under hypoxic conditions was examined, where it was found that polySia expression enhanced cell migration and survival and inhibits cell adhesion. In summary, polyST inhibitors which dramatically decrease cell migration in vitro through modulation of polySia assembly were identified, using optimised cell-free and cell-based assays. Initial investigations into the role of polySia in hypoxia were also accomplished. This work paves the way for development of a novel therapeutic for the treatment of neuroblastoma.
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Differential modulation of glutamatergic synaptic transmission by polysialic acidSims-Robinson, Catrina, Suppiramaniam, Vishnu, January 2007 (has links)
Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references.
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Design, Synthesis and Biological Evaluation of Inhibitors of Polysialyltransferases PST and STX. Design, synthesis and biological evaluation of a range of N-modified mannosamines, sialic acids and analogues from in silico screening as inhibitors of PolySia-NCAM biosynthesis with anti-migration activity.Springett, Bradley R. January 2013 (has links)
Polysialylated NCAM (polySia-NCAM) is re-expressed in a number of tumours, including small cell lung carcinoma and neuroblastoma and is strongly associated with aggressive, invasive and metastatic tumours in the clinic. SiRNA knockdown of the polysialyltransferases (polySTs), the enzymes responsible for polysialylation of neural cell adhesion molecule (NCAM), has been shown to abolish cell migration. PolySia-NCAM is thus a highly attractive novel therapeutic target. A library of potential polyST inhibitors has been synthesised, using substrate-based design and computational chemistry. Compounds synthesised include N-acylmannosamine analogues, thio-linked CMP-sialic acid analogues, N-acyl modified sialic acids and compounds incorporating elements of both approaches. Novel methodology development in the synthesis of many of the compounds is described, notably a novel route to N-acyl sialosides. In addition, compounds identified from in silico screening were considered. Routes to synthesis and isolation of analogues of biologically active compounds are described. Using an enzyme assay, compounds were evaluated for their ability to reduce polySia synthesis through polyST inhibition. Effects of agents on polySia expression in cells, and the ability of compounds to reduce cell migration in vitro was studied using a wound healing ‘scratch assay’.
The data from these experiments revealed a number of potent modulators of polySia assembly and their efficacy in reducing cell migration, as well as the limits of the biosynthetic pathway to accept unnatural sialic acid precursors. This is the first example of polyST inhibition modulating tumour cell migration, and points to the potential of the polysialyltransferases as a therapeutic target in metastatic tumours. / EPSRC and BACR / The full text will be available at the end of the extended embargo: 5th March 2027
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Pharmacological evaluation of the inhibition of polysialyltransferases as a therapeutic strategy in cancer. Characterisation of models for evaluating polysialic acid as a potential therapeutic target and pharmacological assessment of novel polysialyltransferase inhibitorsAl-Saraireh, Yousef M.J. January 2012 (has links)
Neuroblastoma is a highly metastatic and invasive tumour with poor
prognosis. Despite recent advances in the treatment of neuroblastoma,
mortality is still high due to uncontrolled metastatic disease, and novel
therapeutic approaches for the treatment of neuroblastoma are therefore
desperately needed.
A potential novel approach for therapy of neuroblastoma relates to the
polysialic acid decoration of the neural cell adhesion molecule (PSANCAM). PSA-NCAM is selectively re-expressed in a number of tumours
including neuroblastoma, where it is thought to modulate tumour
dissemination. Expression is strongly associated with poor clinical
prognosis and an aggressive tumour phenotype. Inhibition of the
enzymes responsible for synthesis of PSA, the polysialyltransferases
(polySTs) presents a novel and selective therapeutic opportunity.
The aims of the studies described in this thesis are to evaluate PSANCAM expression and function in neuroblastoma, and to develop and
utilise cell-based models to pharmacologically investigate novel polyST
inhibitors.
PSA-NCAM was seen to be highly expressed in neuroblastoma clinical
specimens and associated with phenotypes of tumour aggressiveness. A
screening panel consisting of cell lines with a range of PSA-NCAM
expression types was established and utilised to develop assays for
pharmacologically assessing novel polyST inhibitors. Using cytidine
monophosphate (CMP), a naturally-occurring inhibitor of polySTs, the
robustness of the assays was confirmed before progression to evaluate
novel molecules. From 16 compounds identified in an in vitro screen of
polyST inhibition, three promising polyST inhibitors were identified.
These promising polyST inhibitors modulated PSA-NCAM expression on
the tumour cell surface and led to a significant reduction in cell migration.
Therefore the work presented in this thesis suggests that targeting
polySTs is a promising novel therapeutic strategy for neuroblastoma and
further research in this area is warranted. / Mu'tah University and Jordan Armed Forces, Hashemite Kingdom of Jordan. / The full text will be available at the end of the extended embargo period: 5th March 2027
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Pharmacological evaluation of novel polysialyltransferase inhibitors as anti-metastatic agents and development of analytical methods for assessment of polysialylation inhibition. In vitro assessment of the effects of novel polysialyltransferase inhibitors on tumour cell function and development of quantitative HPLC-based methods for evaluation of novel polysialyltransferase inhibitorsElkashef, Sara M. January 2016 (has links)
Polysialic acid (polySia) is a carbohydrate polymer highly expressed during embryonic development but rarely expressed during postnatal development. Two polysialyltransferase (polyST) enzymes are responsible for the synthesis of polySia: ST8SiaII and ST8SiaIV. During oncogenesis polySia is re-expressed and it modulates cell-cell and cell-matrix adhesion, migration, invasion and metastasis. PolySia expression is strongly associated with poor clinical prognosis and correlates with aggressive and invasive disease in neuroblastoma and many other tumours. PolyST inhibition thus presents a novel, selective and largely unexplored therapeutic opportunity to reduce tumour dissemination.
Progress towards development of polyST inhibitors has been limited by lack of an efficient technique for quantitative assessment of enzyme activity. We have validated a highly sensitive cell-based and cell-free high throughput HPLC-based inhibition assays. Using isogenic cell lines (C6-STX: polySia+/ST8SiaII+ and C6-WT: polySia-/ST8SiaII-) and naturally polySia expressing human neuroblastoma cells (SH-SY5Y), a set of ST8SiaII inhibitors designed and synthesised in house were evaluated for their ability to reduce polySia expression and to modulate cell migration in vitro. We have identified CMP-sialic acid precursors, including ICT-3176, which reduced polySia expression and tumour cell migration by up to 70%. These effects were only found in cell lines expressing ST8SiaII and polySia.
Furthermore, we have investigated the possible additive anti-migratory effect of combining polyST inhibition with the inhibition of certain signalling pathways that have been previously suggested to be modulated by polySia expression. Out of these combinations it was found that combining ST8SiaII and C-MET/ALK inhibition had a synergistic effect on inhibiting cancer cell migration. Additionally, the effect of polySia expression on cancer cell behaviour under hypoxic conditions was examined, where it was found that polySia expression enhanced cell migration and survival and inhibits cell adhesion.
In summary, polyST inhibitors which dramatically decrease cell migration in vitro through modulation of polySia assembly were identified, using optimised cell-free and cell-based assays. Initial investigations into the role of polySia in hypoxia were also accomplished. This work paves the way for development of a novel therapeutic for the treatment of neuroblastoma.
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An optimised assay for quantitative, high-throughput analysis of polysialyltransferase activityElkashef, Sara M., Sutherland, Mark, Patterson, Laurence H., Loadman, Paul, Falconer, Robert A. 07 August 2016 (has links)
Yes / The polysialyltransferases are biologically important glycosyltransferase enzymes responsible for the biosynthesis of
polysialic acid, a carbohydrate polymer that plays a critical role in the progression of several diseases, notably cancer.
Having improved the chemical synthesis and purification of the fluorescently-labelled DMB-DP3 acceptor, we report
optimisation and validation of a highly sensitive cell-free high-throughput HPLC-based assay for assessment of human
polysialyltransferase activity.
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An assay for quantitative analysis of polysialic acid expression in cancer cellsGuo, Xiaoxiao, Elkashef, Sara M., Patel, Anjana, Ribeiro Morais, Goreti, Shnyder, Steven, Loadman, Paul, Patterson, Laurence H., Falconer, Robert A. 15 February 2021 (has links)
Yes / Polysialic acid (polySia) is a linear polysaccharide comprised of N-acetylneuraminic acid residues and its over-expression in cancer cells has been correlated with poor clinical prognosis. An assay has been developed for quantitative analysis of cellular polySia expression. This was achieved by extracting and purifying released polySia from glycoproteins by mild acid hydrolysis and optimised organic extraction. The polySia was further hydrolysed into Sia monomers, followed by fluorescent labelling and quantitative analysis. The assay was qualified utilising endoneuraminidase-NF to remove polySia from the surface of C6-ST8SiaII cancer cells (EC50 = 2.13 ng/ml). The result was comparable to that obtained in a polySia-specific cellular ELISA assay. Furthermore, the assay proved suitable for evaluation of changes in polySia expression following treatment with a small molecule inhibitor of polysialylation. Given the importance of polySia in multiple disease states, notably cancer, this is a potentially vital tool with applications in the fields of drug discovery and glycobiology.
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Investigation of inhibitors of polysialyltransferase as novel therapeutics for neuroblastoma : development of in vitro assays to assess the functionality and selectivity of novel small-molecule inhibitors of polysialyltransferases for use in neuroblastoma therapySaeed, Rida Fatima January 2015 (has links)
Polysialic acid is a unique carbohydrate that decorates the surface of the neural cell adhesion molecule. Polysialic acid is an onco-developmental antigen, expressed in tumours principally of neuroendocrine origin, notably neuroblastoma, strongly correlating with invasion and metastasis. Polysialylation is regulated by two polysialyltransferase enzymes, PST (ST8SiaIV) and STX (ST8SiaII), with STX dominant in cancer. Post-development polysialic acid expression is only found at low levels in the brain, thus this could be a novel target for cancer therapy. It is hypothesized that inhibition of polysialyltransferase could lead to control of tumour dissemination and metastasis. The aims of this thesis were to develop tools and in vitro assays to screen novel polysialyltransferase inhibitors. A panel of tumour cell lines were characterised in terms of growth parameters (using the MTT assay) and polysialic acid expression. This includes a pair of isogenic C6 rat glioma cells (C6-STX and C6-WT) and naturally polysialic acid expressing neuroblastoma cells (SH-SY5Y). Following this, an in vitro assay was validated to screen modulation of polysialic acid expression by removing pre-existing polysialic acid expression using endoneuraminidase N and evaluated the amount of re-expression of polysialic acid using immunocytochemistry. Then, a functional assay was developed and validated for invasion, the matrigel invasion assay. Cytidine monophosphate (tool compound) significantly reduced polysialic acid surface expression and invasion. A panel of six novel polysialyltransferase inhibitors was screened for cytotoxicity, polysialic acid surface expression and invasion. Of the potential polysialyltransferase inhibitors evaluated, ICT3176 and ICT3172 were identified from virtual screening of Maybridge library and were emerged as the most promising inhibitors, demonstrating significant (p < 0.05) reduction in cell-surface polysialic acid re-expression and invasion in polysialic acid expressing cells. Furthermore, the specificity of compounds for polysialyltransferase (α-2,8-sialyltransferase) over other members of the wider sialyltransferase family (α-2,3- and α-2,6-sialyltransferases) was confirmed using differential lectin staining. These results demonstrated that small molecule inhibitors as STX is possible and provides suitable in vitro cell based assays to discovery more potent derivatives.
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Investigation of inhibitors of polysialyltransferase as novel therapeutics for neuroblastoma. Development of in vitro assays to assess the functionality and selectivity of novel small-molecule inhibitors of polysialyltransferases for use in neuroblastoma therapySaeed, Rida F. January 2015 (has links)
Polysialic acid is aunique carbohydrate that decorates the surface of the neural cell adhesion molecule. Polysialic acidis an onco-developmental antigen, expressed in tumours principally of neuroendocrine origin, notably neuroblastoma,strongly correlating with invasion and metastasis. Polysialylation is regulated by two polysialyltransferase enzymes, PST(ST8SiaIV)and STX(ST8SiaII),withSTX dominant in cancer. Post-development polysialic acid expression is only found at low levels in the brain, thus this could be a novel target for cancer therapy. It is hypothesized that inhibition of polysialyltransferasecould lead to control of tumour dissemination and metastasis.The aims of this thesis were to develop tools and in vitro assays to screen novel polysialyltransferaseinhibitors. A panel of tumour cell lines were characterised in terms of growth parameters (using the MTT assay) and polysialic acid expression. This includes a pair of isogenic C6 rat glioma cells (C6-STX and C6-WT) and naturally polysialic acid expressing neuroblastoma cells(SH-SY5Y). Following this, an in vitro assay was validated to screen modulation of polysialic acid expression by removing pre-existing polysialic acid expression using endoneuraminidase N and evaluated the amount of re-expression of polysialic acid using immunocytochemistry. Then, a functional assay was developed and validated for invasion, the matrigel invasion assay. Cytidine monophosphate (tool compound) significantly reduced polysialic acidsurface expression and invasion. A panel of six novel polysialyltransferase inhibitors was screened for cytotoxicity, polysialic acidsurface expression and invasion. Of the potential polysialyltransferase inhibitorsevaluated, ICT3176 and ICT3172 were identified from virtual screening of Maybridge library and were emerged as the most promising inhibitors, demonstrating significant (p<0.05)reduction in cell-surface polysialic acidre-expression and invasion in polysialic acid expressing cells.Furthermore, the specificity of compounds for polysialyltransferase (α-2,8-sialyltransferase) over othermembers of the wider sialyltransferase family (α-2,3-and α-2,6-sialyltransferases) was confirmed using differential lectin staining. These results demonstrated that small molecule inhibitors as STX is possible and provides suitable in vitrocell based assays to discovery more potent derivatives.
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