Aims: To develop and validate an analytical procedure for the quantitation of pepsins and gastric... more Aims: To develop and validate an analytical procedure for the quantitation of pepsins and gastricsin in human gastric juice and to assess its potential in a controlled gastric secretory study. Methods: High performance ionexchange chromatography was used to separate human pepsin 1, 3a, 3b, 3c and gastricsin from gastric juice. Computed chromatographic areas for each enzyme were quantified by relation to a known amount of a secondary standard porcine pepsin. The assay procedure was validated by recovery and analytical precision studies. Gastric secretions after pentagastrin and insulin stimulation from 10 patients with portal hypertension were used to assess the potential of the analytical procedure. Results: The assay precision varied from 1.5 to 9*0% within batch and 7 5 to 181% between batch, with about 100% recoveries of porcine pepsin A from human gastric juice over the assay range 0 025-0 5mg/ml. A fourfold increase in combined pepsin and gastricsin concentration was observed following pentagastrin and insulin stimulation. The mean percentage content of pepsins 3a, 3b, 3c, and 1 in non-stimulated gastric juice
Co py ri g h t a n d m o r al ri g h t s fo r p u blic a tio n s m a d e a v ail a bl e in ORCA a... more Co py ri g h t a n d m o r al ri g h t s fo r p u blic a tio n s m a d e a v ail a bl e in ORCA a r e r e t ai n e d by t h e c o py ri g h t h ol d e r s .
In Wales, around 20% of the population (580,000) speak Welsh 1. Although most of these also speak... more In Wales, around 20% of the population (580,000) speak Welsh 1. Although most of these also speak English, it has been reported that bilingual patients find it easier to communicate in their first language in times of stress, for example when ill 2,3,4,5. Prior research specifically relating to community pharmacy has found that Welsh-speakers would generally prefer to use Welsh when discussing health issues, yet that option is not always available to them 4, 5. Indeed, there is no formal requirement for community pharmacists working in Wales to possess Welsh language skills. Further, the number and distribution of community pharmacies in Wales with Welsh-speaking staff is currently unknown. The aim of this study was to investigate the role of the Welsh language in community pharmacies in Wales. In particular, the (Welsh) language abilities of pharmacy staff, the availability of Welsh-speaking staff during pharmacy opening hours and community pharmacists' perceptions and experiences of a local need for Welsh-language services. A further intention was to investigate how these issues relate to geographical area based on the levels of Welsh-speakers in each area. The self-complete postal questionnaire was sent to every community pharmacy in Wales (n=715). After two follow-up mailings, a response rate of 76% was achieved. The results show that while there are high levels of Welsh-language provision in some pharmacies, this is not the case uniformly across Wales. Indeed, the levels of Welsh-speaking pharmacy staff vary widely from region to region and appear to mirror the data from the 2001 census showing levels of Welsh-speaking ability in the different areas of Wales. Promotion of the availability of pharmacy services through the medium of Welsh relied, in most cases, on local knowledge-meaning that even those Welsh-speakers who do have access to Welsh-language pharmacy services may not realise this. In addition to finding the baseline for current levels of provision of community pharmacy services through the medium of Welsh, this study suggests important follow-up work to examine how this provision can be extended.
Native pig pepsin was analysed by negative ion electrospray mass spectrometry in order to rationa... more Native pig pepsin was analysed by negative ion electrospray mass spectrometry in order to rationalize anomalies between the published sequences. Outstanding variations in otherwise identical sequences indicate that amino acid residue 242 is either Asp or Tyr, and in some determinations an additional Ile is inserted at position 230. Mass spectrometric evidence is consistent with the presence, in the native enzyme, of two variants in comparable abundance, with either Asp or Tyr at residue 242. There is no evidence for the additional Ile at position 230.
The cell interaction, mechanism of cell entry and intracellular fate of surface decorated nanopar... more The cell interaction, mechanism of cell entry and intracellular fate of surface decorated nanoparticles are known to be affected by the surface density of targeting agents. However, the correlation between nanoparticles multivalency and kinetics of the cell uptake process and disposition of intracellular compartments is complicated and dependent on a number of physicochemical and biological parameters, including the ligand, nanoparticle composition and colloidal properties, features of targeted cells, etc. Here, we have carried out an in-depth investigation on the impact of increasing folic acid density on the kinetic uptake process and endocytic route of folate (FA)-targeted fluorescently labelled gold nanoparticles (AuNPs). A set of AuNPs (15 nm mean size) produced by the Turkevich method was decorated with 0–100 FA-PEG3.5kDa-SH molecules/particle, and the surface was saturated with about 500 rhodamine-PEG2kDa-SH fluorescent probes. In vitro studies carried out using folate recept...
In the quest to decipher the chain of life from molecules to cells, the biological and biophysica... more In the quest to decipher the chain of life from molecules to cells, the biological and biophysical questions being asked increasingly demand techniques that are capable of identifying specific biomolecules in their native environment, and can measure biomolecular interactions quantitatively, at the smallest possible scale in space and time, without perturbing the system under observation. The interaction of light with biomolecules offers a wealth of phenomena and tools that can be exploited to drive this progress. This Roadmap is written collectively by prominent researchers and encompasses selected aspects of bio-nano-photonics, spanning from the development of optical micro/nano-spectroscopy technologies for quantitative bioimaging and biosensing to the fundamental understanding of light–matter interaction phenomena with biomolecules at the nanoscale. It will be of interest to a wide cross-disciplinary audience in the physical sciences and life sciences.
Selective targeting of cells for intracellular delivery of therapeutics represents a major challe... more Selective targeting of cells for intracellular delivery of therapeutics represents a major challenge for pharmaceutical intervention in disease. Here we show pH-triggered receptor-mediated endocytosis of nanoparticles via surface ligand exposure. Gold nanoparticles were decorated with two polymers: a 2 kDa PEG with a terminal folate targeting ligand, and a di-block copolymer including a pH-responsive and a hydrophilic block. At the normal serum pH of 7.4, the pH-responsive block (apparent pKa of 7.1) displayed a hydrophilic extended conformation, shielding the PEG-folate ligands, which inhibited cellular uptake of the nanoparticles. Under pH conditions resembling those of the extracellular matrix around solid tumours (pH 6.5), protonation of the pH-responsive polymer triggered a coil-to-globule polymer chain contraction, exposing folate residues on the PEG chains. In line with this, endocytosis of folate-decorated polymer-coated gold nanoparticles in cancer cells overexpressing fola...
Journal of interdisciplinary nanomedicine, Jun 1, 2018
Endocytosis is an essential function of cells, with key roles in the internalisation of nutrients... more Endocytosis is an essential function of cells, with key roles in the internalisation of nutrients, signal molecules and also drugs. Endocytic processes are therefore widely investigated in the context of drug delivery, and inhibitors of endocytic pathways have been used to provide information regarding uptake mechanisms of drug carrier materials. Here we describe studies in which two established inhibitors of clathrin dependent and independent endocytosis, chlorpromazine and methyl-β-cyclodextrin respectively, were employed to probe endocytic pathways of three cell lines chosen to represent tumour-relevant or associated phenotypes: 3 T3 (fibroblasts), HCT 116 (colon cancer) and MGLVA-1 (gastric cancer). For clathrin mediated endocytosis the data highlight that chlorpromazine inhibition of transferrin internalization, via clathrin dependent endocytosis, is cell and time dependent. We also show that inhibition of uptake is transient with a resumption of transferrin internalization after a maximal inhibition period. The same endocytosis inhibitors were used to probe the internalization of 50 and 100 nm carboxylated polystyrene nanoparticles (C-PS-NPs) as model drug delivery carriers. Flow cytometry data indicated that internalisation of C-PS-NPs varied considerably with the incubation time of cells with chlorpromazine or methyl-β-cyclodextrin, and that the effects were also markedly cellline dependent. These data highlight that the effects of endocytosis inhibitors on the internalisation pathways even of relatively simple nanoparticles are complex and interdependent. We suggest that mechanistic investigations of the endocytic processes which govern practical applications of nanoparticles for diagnostic and therapeutic applications should be considered on a cell, time and concentration basis.
Recently, 3-dimensional supramolecular coordination complexes of the metallacage type have been s... more Recently, 3-dimensional supramolecular coordination complexes of the metallacage type have been shown to hold promise as drug delivery systems for different cytotoxic agents, including the anticancer drug cisplatin. However, so far only limited information is available on their uptake and sub-cellular localisation in cancer cells. With the aim of understanding the fate of metallacages in cells by fluorescence microscopy, three fluorescent Pd2L4 metallacages were designed and synthesised by self-assembly of two types of bispyridyl ligands (L), exo-functionalised with boron dipyrromethene (BODIPY) moieties, with Pd(II) ions. The cages show high quantum yields and are moderately stable in the presence of physiologically relevant concentration of glutathione. Furthermore, the cages are able to encapsulate the anticancer drug cisplatin, as demonstrated by NMR spectroscopy. Preliminary cytotoxicity studies in a small panel of human cancer cells showed that the metallacages are scarcely toxic in vitro. The marked fluorescence due to BODIPY allowed us to visualise the 2 cages' uptake and sub-cellular localisation inside melanoma cells using fluorescence microscopy, highlighting uptake via active transport mechanisms and accumulation in cytoplasmic vesicles.
The insides of cells can be viewed as a treasure trove of targets for therapeutic intervention of... more The insides of cells can be viewed as a treasure trove of targets for therapeutic intervention of diseases or as deposits for contrasting agents. Increasingly the molecules that need to be delivered to the inside of cells for these purposes are macromolecular and membrane impermeable. Cell penetrating peptides (CPPs) have proven abilities to deliver a range of macromolecular cargo into cells thus raising their profile as potential delivery vectors for wide-ranging applications. There is evidence to suggest that CPPs first enter cells through endocytosis and that cytosolic delivery is mediated across endolysosomal membranes. Their capacity to do this, over direct plasma membrane translocation, is likely to depend on the nature and size of the cargo. Cells use a range of endocytic routes to facilitate entry from well characterised pathways regulated by clathrin to more recently discovered and less characterised pathways regulated by clathrin independent mechanisms. These are likely to determine the intracellular fate of cell delivery vectors including those based on cell penetrating peptides. Thus gaining accurate knowledge of their endocytic uptake and traffic is an important characterisation criteria for progress in this field. This review describes the different endocytic pathways that have been identified in mammalian cells and specific reports that have studied the uptake mechanisms and endocytic traffic of cell penetrating peptides and their associated cargo. These cargoes range from short peptides to an increasing library of nanoparticles such as quantum dots, liposomes and polymeric dendrimers. The studies highlight the effectiveness of cell penetrating peptides for delivering these entities into a diverse array of cell types using different endocytic pathways. This is shown using microscopy based colocalisation analysis with the few specific endocytic probes available, and chemical inhibitors of endocytosis that suffer from lack of specificity. Overall, more specific probes, inhibitors and novel technologies are required for accurate characterisation of cellular dynamics of cell penetrating peptide conjugates thus allowing them to reach their full potential as vectors for therapeutics and other payloads.
In mammalian cells, fusion between early endocytic vesicles has been shown to require the ubiquit... more In mammalian cells, fusion between early endocytic vesicles has been shown to require the ubiquitous intracellular fusion factors N-ethylmaleimide-sensitive factor (NSF) and α-SNAP, as well as a factor specific for early endosomes, the small GTPase Rab5 [1–3]. We have previously demonstrated an additional requirement for phosphatidylinositol 3-kinase (PI 3-kinase) activity [4]. The membrane association of early endosomal antigen 1 (EEA1),
Series of substituted 4,6-diamino-1,3,5-triazine-2-carbohydrazides and -carboxamides have been sy... more Series of substituted 4,6-diamino-1,3,5-triazine-2-carbohydrazides and -carboxamides have been synthesised, based on molecular modelling of candidate structures related to the previously reported Rad6B-inhibitory diamino-triazinylmethyl benzoate anticancer agents TZ8 and TZ9. Synthesis of the target compounds was readily accomplished in two steps from aryl biguanides via reaction of phenylhydrazine or benzylamines with key 4-amino-6-(arylamino)-1,3,5-triazine-2-carboxylate intermediates. These new triazine derivatives were tested for in vitro anticancer activity against the Rad6B expressing human breast cancer cell lines MDA-MB-231 and MCF-7. Active compounds, such as the triazinyl-carbohydrazides 3a-e, were found to exhibit low micromolar IC50 values particularly in the Rad6B-overexpressing MDA-MB-231 cell line.
A series of substituted 3-(benzylthio)-5-(1H-indol-3-yl)-4H-1,2,4-triazol-4-amines has been synth... more A series of substituted 3-(benzylthio)-5-(1H-indol-3-yl)-4H-1,2,4-triazol-4-amines has been synthesised and tested in vitro as potential pro-apoptotic Bcl-2-inhibitory anticancer agents. Synthesis of the target compounds was readily accomplished in good yields through a cyclisation reaction between indole-3-carboxylic acid hydrazide and carbon disulfide under basic conditions, followed by S-benzylation. Active compounds, such as the nitrobenzyl analogue 6c, were found to exhibit sub-micromolar IC50 values in Bcl-2 expressing human cancer cell lines. Molecular modelling and ELISA studies further implicated anti-apoptotic Bcl-2 as a candidate molecular target underpinning anticancer activity.
Extensive research is currently performed on designing safe and efficient non-viral carriers for ... more Extensive research is currently performed on designing safe and efficient non-viral carriers for gene delivery. To increase their efficiency, it is essential to have a thorough understanding of the mechanisms involved in cellular attachment, internalization and intracellular processing in target cells. In this work, we studied in vitro the cellular dynamics of polyplexes, composed of a newly developed bioreducible poly(amido amine) carrier, formed by polyaddition of N,N-cystamine bisacrylamide and 1-amino-4-butanol (p(CBA-ABOL)) on retinal pigment epithelium (RPE) cells, which are attractive targets for ocular gene therapy. We show that these net cationic p(CBA-ABOL)/DNA polyplexes require a charge-mediated attachment to the sulfate groups of cell surface heparan sulfate proteoglycans in order to be efficiently internalized. Secondly, we assessed the involvement of defined endocytic pathways in the internalization of the polyplexes in ARPE-19 cells by using a combination of endocytic inhibitors, RNAi depletion of endocytic proteins and live cell fluorescence colocalization microscopy. We found that the p(CBA-ABOL) polyplexes enter RPE cells both via flotillindependent endocytosis and a PAK1 dependent phagocytosis-like mechanism. The capacity of polyplexes to transfect cells was, however, primarily dependent on a flotillin-1-dependent endocytosis pathway.
Aims: To develop and validate an analytical procedure for the quantitation of pepsins and gastric... more Aims: To develop and validate an analytical procedure for the quantitation of pepsins and gastricsin in human gastric juice and to assess its potential in a controlled gastric secretory study. Methods: High performance ionexchange chromatography was used to separate human pepsin 1, 3a, 3b, 3c and gastricsin from gastric juice. Computed chromatographic areas for each enzyme were quantified by relation to a known amount of a secondary standard porcine pepsin. The assay procedure was validated by recovery and analytical precision studies. Gastric secretions after pentagastrin and insulin stimulation from 10 patients with portal hypertension were used to assess the potential of the analytical procedure. Results: The assay precision varied from 1.5 to 9*0% within batch and 7 5 to 181% between batch, with about 100% recoveries of porcine pepsin A from human gastric juice over the assay range 0 025-0 5mg/ml. A fourfold increase in combined pepsin and gastricsin concentration was observed following pentagastrin and insulin stimulation. The mean percentage content of pepsins 3a, 3b, 3c, and 1 in non-stimulated gastric juice
Co py ri g h t a n d m o r al ri g h t s fo r p u blic a tio n s m a d e a v ail a bl e in ORCA a... more Co py ri g h t a n d m o r al ri g h t s fo r p u blic a tio n s m a d e a v ail a bl e in ORCA a r e r e t ai n e d by t h e c o py ri g h t h ol d e r s .
In Wales, around 20% of the population (580,000) speak Welsh 1. Although most of these also speak... more In Wales, around 20% of the population (580,000) speak Welsh 1. Although most of these also speak English, it has been reported that bilingual patients find it easier to communicate in their first language in times of stress, for example when ill 2,3,4,5. Prior research specifically relating to community pharmacy has found that Welsh-speakers would generally prefer to use Welsh when discussing health issues, yet that option is not always available to them 4, 5. Indeed, there is no formal requirement for community pharmacists working in Wales to possess Welsh language skills. Further, the number and distribution of community pharmacies in Wales with Welsh-speaking staff is currently unknown. The aim of this study was to investigate the role of the Welsh language in community pharmacies in Wales. In particular, the (Welsh) language abilities of pharmacy staff, the availability of Welsh-speaking staff during pharmacy opening hours and community pharmacists' perceptions and experiences of a local need for Welsh-language services. A further intention was to investigate how these issues relate to geographical area based on the levels of Welsh-speakers in each area. The self-complete postal questionnaire was sent to every community pharmacy in Wales (n=715). After two follow-up mailings, a response rate of 76% was achieved. The results show that while there are high levels of Welsh-language provision in some pharmacies, this is not the case uniformly across Wales. Indeed, the levels of Welsh-speaking pharmacy staff vary widely from region to region and appear to mirror the data from the 2001 census showing levels of Welsh-speaking ability in the different areas of Wales. Promotion of the availability of pharmacy services through the medium of Welsh relied, in most cases, on local knowledge-meaning that even those Welsh-speakers who do have access to Welsh-language pharmacy services may not realise this. In addition to finding the baseline for current levels of provision of community pharmacy services through the medium of Welsh, this study suggests important follow-up work to examine how this provision can be extended.
Native pig pepsin was analysed by negative ion electrospray mass spectrometry in order to rationa... more Native pig pepsin was analysed by negative ion electrospray mass spectrometry in order to rationalize anomalies between the published sequences. Outstanding variations in otherwise identical sequences indicate that amino acid residue 242 is either Asp or Tyr, and in some determinations an additional Ile is inserted at position 230. Mass spectrometric evidence is consistent with the presence, in the native enzyme, of two variants in comparable abundance, with either Asp or Tyr at residue 242. There is no evidence for the additional Ile at position 230.
The cell interaction, mechanism of cell entry and intracellular fate of surface decorated nanopar... more The cell interaction, mechanism of cell entry and intracellular fate of surface decorated nanoparticles are known to be affected by the surface density of targeting agents. However, the correlation between nanoparticles multivalency and kinetics of the cell uptake process and disposition of intracellular compartments is complicated and dependent on a number of physicochemical and biological parameters, including the ligand, nanoparticle composition and colloidal properties, features of targeted cells, etc. Here, we have carried out an in-depth investigation on the impact of increasing folic acid density on the kinetic uptake process and endocytic route of folate (FA)-targeted fluorescently labelled gold nanoparticles (AuNPs). A set of AuNPs (15 nm mean size) produced by the Turkevich method was decorated with 0–100 FA-PEG3.5kDa-SH molecules/particle, and the surface was saturated with about 500 rhodamine-PEG2kDa-SH fluorescent probes. In vitro studies carried out using folate recept...
In the quest to decipher the chain of life from molecules to cells, the biological and biophysica... more In the quest to decipher the chain of life from molecules to cells, the biological and biophysical questions being asked increasingly demand techniques that are capable of identifying specific biomolecules in their native environment, and can measure biomolecular interactions quantitatively, at the smallest possible scale in space and time, without perturbing the system under observation. The interaction of light with biomolecules offers a wealth of phenomena and tools that can be exploited to drive this progress. This Roadmap is written collectively by prominent researchers and encompasses selected aspects of bio-nano-photonics, spanning from the development of optical micro/nano-spectroscopy technologies for quantitative bioimaging and biosensing to the fundamental understanding of light–matter interaction phenomena with biomolecules at the nanoscale. It will be of interest to a wide cross-disciplinary audience in the physical sciences and life sciences.
Selective targeting of cells for intracellular delivery of therapeutics represents a major challe... more Selective targeting of cells for intracellular delivery of therapeutics represents a major challenge for pharmaceutical intervention in disease. Here we show pH-triggered receptor-mediated endocytosis of nanoparticles via surface ligand exposure. Gold nanoparticles were decorated with two polymers: a 2 kDa PEG with a terminal folate targeting ligand, and a di-block copolymer including a pH-responsive and a hydrophilic block. At the normal serum pH of 7.4, the pH-responsive block (apparent pKa of 7.1) displayed a hydrophilic extended conformation, shielding the PEG-folate ligands, which inhibited cellular uptake of the nanoparticles. Under pH conditions resembling those of the extracellular matrix around solid tumours (pH 6.5), protonation of the pH-responsive polymer triggered a coil-to-globule polymer chain contraction, exposing folate residues on the PEG chains. In line with this, endocytosis of folate-decorated polymer-coated gold nanoparticles in cancer cells overexpressing fola...
Journal of interdisciplinary nanomedicine, Jun 1, 2018
Endocytosis is an essential function of cells, with key roles in the internalisation of nutrients... more Endocytosis is an essential function of cells, with key roles in the internalisation of nutrients, signal molecules and also drugs. Endocytic processes are therefore widely investigated in the context of drug delivery, and inhibitors of endocytic pathways have been used to provide information regarding uptake mechanisms of drug carrier materials. Here we describe studies in which two established inhibitors of clathrin dependent and independent endocytosis, chlorpromazine and methyl-β-cyclodextrin respectively, were employed to probe endocytic pathways of three cell lines chosen to represent tumour-relevant or associated phenotypes: 3 T3 (fibroblasts), HCT 116 (colon cancer) and MGLVA-1 (gastric cancer). For clathrin mediated endocytosis the data highlight that chlorpromazine inhibition of transferrin internalization, via clathrin dependent endocytosis, is cell and time dependent. We also show that inhibition of uptake is transient with a resumption of transferrin internalization after a maximal inhibition period. The same endocytosis inhibitors were used to probe the internalization of 50 and 100 nm carboxylated polystyrene nanoparticles (C-PS-NPs) as model drug delivery carriers. Flow cytometry data indicated that internalisation of C-PS-NPs varied considerably with the incubation time of cells with chlorpromazine or methyl-β-cyclodextrin, and that the effects were also markedly cellline dependent. These data highlight that the effects of endocytosis inhibitors on the internalisation pathways even of relatively simple nanoparticles are complex and interdependent. We suggest that mechanistic investigations of the endocytic processes which govern practical applications of nanoparticles for diagnostic and therapeutic applications should be considered on a cell, time and concentration basis.
Recently, 3-dimensional supramolecular coordination complexes of the metallacage type have been s... more Recently, 3-dimensional supramolecular coordination complexes of the metallacage type have been shown to hold promise as drug delivery systems for different cytotoxic agents, including the anticancer drug cisplatin. However, so far only limited information is available on their uptake and sub-cellular localisation in cancer cells. With the aim of understanding the fate of metallacages in cells by fluorescence microscopy, three fluorescent Pd2L4 metallacages were designed and synthesised by self-assembly of two types of bispyridyl ligands (L), exo-functionalised with boron dipyrromethene (BODIPY) moieties, with Pd(II) ions. The cages show high quantum yields and are moderately stable in the presence of physiologically relevant concentration of glutathione. Furthermore, the cages are able to encapsulate the anticancer drug cisplatin, as demonstrated by NMR spectroscopy. Preliminary cytotoxicity studies in a small panel of human cancer cells showed that the metallacages are scarcely toxic in vitro. The marked fluorescence due to BODIPY allowed us to visualise the 2 cages' uptake and sub-cellular localisation inside melanoma cells using fluorescence microscopy, highlighting uptake via active transport mechanisms and accumulation in cytoplasmic vesicles.
The insides of cells can be viewed as a treasure trove of targets for therapeutic intervention of... more The insides of cells can be viewed as a treasure trove of targets for therapeutic intervention of diseases or as deposits for contrasting agents. Increasingly the molecules that need to be delivered to the inside of cells for these purposes are macromolecular and membrane impermeable. Cell penetrating peptides (CPPs) have proven abilities to deliver a range of macromolecular cargo into cells thus raising their profile as potential delivery vectors for wide-ranging applications. There is evidence to suggest that CPPs first enter cells through endocytosis and that cytosolic delivery is mediated across endolysosomal membranes. Their capacity to do this, over direct plasma membrane translocation, is likely to depend on the nature and size of the cargo. Cells use a range of endocytic routes to facilitate entry from well characterised pathways regulated by clathrin to more recently discovered and less characterised pathways regulated by clathrin independent mechanisms. These are likely to determine the intracellular fate of cell delivery vectors including those based on cell penetrating peptides. Thus gaining accurate knowledge of their endocytic uptake and traffic is an important characterisation criteria for progress in this field. This review describes the different endocytic pathways that have been identified in mammalian cells and specific reports that have studied the uptake mechanisms and endocytic traffic of cell penetrating peptides and their associated cargo. These cargoes range from short peptides to an increasing library of nanoparticles such as quantum dots, liposomes and polymeric dendrimers. The studies highlight the effectiveness of cell penetrating peptides for delivering these entities into a diverse array of cell types using different endocytic pathways. This is shown using microscopy based colocalisation analysis with the few specific endocytic probes available, and chemical inhibitors of endocytosis that suffer from lack of specificity. Overall, more specific probes, inhibitors and novel technologies are required for accurate characterisation of cellular dynamics of cell penetrating peptide conjugates thus allowing them to reach their full potential as vectors for therapeutics and other payloads.
In mammalian cells, fusion between early endocytic vesicles has been shown to require the ubiquit... more In mammalian cells, fusion between early endocytic vesicles has been shown to require the ubiquitous intracellular fusion factors N-ethylmaleimide-sensitive factor (NSF) and α-SNAP, as well as a factor specific for early endosomes, the small GTPase Rab5 [1–3]. We have previously demonstrated an additional requirement for phosphatidylinositol 3-kinase (PI 3-kinase) activity [4]. The membrane association of early endosomal antigen 1 (EEA1),
Series of substituted 4,6-diamino-1,3,5-triazine-2-carbohydrazides and -carboxamides have been sy... more Series of substituted 4,6-diamino-1,3,5-triazine-2-carbohydrazides and -carboxamides have been synthesised, based on molecular modelling of candidate structures related to the previously reported Rad6B-inhibitory diamino-triazinylmethyl benzoate anticancer agents TZ8 and TZ9. Synthesis of the target compounds was readily accomplished in two steps from aryl biguanides via reaction of phenylhydrazine or benzylamines with key 4-amino-6-(arylamino)-1,3,5-triazine-2-carboxylate intermediates. These new triazine derivatives were tested for in vitro anticancer activity against the Rad6B expressing human breast cancer cell lines MDA-MB-231 and MCF-7. Active compounds, such as the triazinyl-carbohydrazides 3a-e, were found to exhibit low micromolar IC50 values particularly in the Rad6B-overexpressing MDA-MB-231 cell line.
A series of substituted 3-(benzylthio)-5-(1H-indol-3-yl)-4H-1,2,4-triazol-4-amines has been synth... more A series of substituted 3-(benzylthio)-5-(1H-indol-3-yl)-4H-1,2,4-triazol-4-amines has been synthesised and tested in vitro as potential pro-apoptotic Bcl-2-inhibitory anticancer agents. Synthesis of the target compounds was readily accomplished in good yields through a cyclisation reaction between indole-3-carboxylic acid hydrazide and carbon disulfide under basic conditions, followed by S-benzylation. Active compounds, such as the nitrobenzyl analogue 6c, were found to exhibit sub-micromolar IC50 values in Bcl-2 expressing human cancer cell lines. Molecular modelling and ELISA studies further implicated anti-apoptotic Bcl-2 as a candidate molecular target underpinning anticancer activity.
Extensive research is currently performed on designing safe and efficient non-viral carriers for ... more Extensive research is currently performed on designing safe and efficient non-viral carriers for gene delivery. To increase their efficiency, it is essential to have a thorough understanding of the mechanisms involved in cellular attachment, internalization and intracellular processing in target cells. In this work, we studied in vitro the cellular dynamics of polyplexes, composed of a newly developed bioreducible poly(amido amine) carrier, formed by polyaddition of N,N-cystamine bisacrylamide and 1-amino-4-butanol (p(CBA-ABOL)) on retinal pigment epithelium (RPE) cells, which are attractive targets for ocular gene therapy. We show that these net cationic p(CBA-ABOL)/DNA polyplexes require a charge-mediated attachment to the sulfate groups of cell surface heparan sulfate proteoglycans in order to be efficiently internalized. Secondly, we assessed the involvement of defined endocytic pathways in the internalization of the polyplexes in ARPE-19 cells by using a combination of endocytic inhibitors, RNAi depletion of endocytic proteins and live cell fluorescence colocalization microscopy. We found that the p(CBA-ABOL) polyplexes enter RPE cells both via flotillindependent endocytosis and a PAK1 dependent phagocytosis-like mechanism. The capacity of polyplexes to transfect cells was, however, primarily dependent on a flotillin-1-dependent endocytosis pathway.
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Papers by Arwyn Jones