quyen nguyen - Academia.edu (original) (raw)
Papers by quyen nguyen
Proceedings of The National Academy of Sciences, 2004
We have devised and tested a new strategy for selectively delivering molecules to tumor cells. Ce... more We have devised and tested a new strategy for selectively delivering molecules to tumor cells. Cellular association of polyargininebased, cell-penetrating peptides (CPPs) is effectively blocked when they are fused to an inhibitory domain made up of negatively charged residues. We call these fusions activatable CPPs (ACPPs) because cleavage of the linker between the polycationic and polyanionic domains, typically by a protease, releases the CPP portion and its attached cargo to bind to and enter cells. Association with cultured cells typically increases 10-fold or more upon linker cleavage. In mice xenografted with human tumor cells secreting matrix metalloproteinases 2 and 9, ACPPs bearing a far-red-fluorescent cargo show in vivo contrast ratios of 2-3 and a 3.1-fold increase in standard uptake value for tumors relative to contralateral normal tissue or control peptides with scrambled linkers. Ex vivo slices of freshly resected human squamous cell carcinomas give similar or better contrast ratios. Because CPPs are known to import a wide variety of nonoptical contrast and therapeutic agents, ACPPs offer a general strategy toward imaging and treating disease processes associated with linker-cleaving activities such as extracellular proteases.
Integrative Biology, 2009
Activatable cell penetrating peptides (ACPPs) are novel in vivo targeting agents comprised of a p... more Activatable cell penetrating peptides (ACPPs) are novel in vivo targeting agents comprised of a polycationic cell penetrating peptide (CPP) connected via a cleavable linker to a neutralizing polyanion . Adsorption and uptake into cells are inhibited until the linker is proteolyzed1 -3 . An ACPP cleavable by matrix metalloproteinase-2 (MMP-2) in vitro was the first one demonstrated to work in a tumor model in vivo, but only HT-1080 xenografts and resected human squamous cell carcinomas were tested. Generality to other cancer types, in vivo selectivity of ACPPs for MMPs, and spatial resolution require further characterization. We now show that ACPPs can target many xenograft tumor models from different cancer sites, as well as a well thoroughly studied transgenic model of spontaneous breast cancer (mouse mammary tumor virus promoter driving polyoma middle T antigen, MMTV-PyMT). Pharmacological inhibitors and genetic knockouts indicate that current ACPPs are selective for MMP-2 and MMP-9 in the above in vivo models. In accord with the known local distribution of MMP activity, accumulation is strongest at the tumor-stromal interface in primary tumors and associated metastases, indicating better spatial resolution (<50 µm) than other currently available MMP-cleavable probes 4 . We also find that background uptake of ACPPs into normal tissues such as liver and kidney can be decreased by appending inert macromolecules of 30-50 KDa to the polyanionic inhibitory domain. Our results validate an approach that should generally deliver imaging agents and chemotherapeutics to sites of invasion, tumor-promoting inflammation, and metastasis.
Nature Neuroscience, 2002
A large body of evidence shows that molecular cues promote specific synapse formation by guiding ... more A large body of evidence shows that molecular cues promote specific synapse formation by guiding axons and by mediating their association with targets, but much less is known about the contribution of physical cues (such as mechanical constraints) to these processes. Here we used the peripheral motor system to investigate the latter issue. In living mice, we viewed individual motor axons bearing a fluorescent reporter, and mapped the cohort of muscle fibers that they innervated both before and after nerve damage. When gross trauma was minimized (by a nerve-crushing rather than nerve-cutting procedure), regenerating axons retraced their former pathways, bifurcated at original branch points, and formed neuromuscular junctions on the same fibers that they originally innervated. Axonal growth through tubes of non-neural cells seemed to account for this specificity, and specificity degraded when the tubes were cut. These results suggest that nonspecific guidance cues can be sufficient to generate specific synaptic circuitry.
Current Opinion in Neurobiology, 1996
Neuron, 2000
The first report on GFP expression in heterologous cells illustrated its use as a vital stain for... more The first report on GFP expression in heterologous cells illustrated its use as a vital stain for neurons (Chalfie Washington University School of Medicine St. Louis, Missouri 63110 et al., 1994). Since that time, neuroscience has been one of the greatest beneficiaries of GFP technology, and GFP has been used to facilitate the study of neuronal development and plasticity in transgenic worms, flies, fish, and mice (for example, Dynes and Ngai, 1998; Mur-Summary ray et al., 1998; van den Pol and Ghosh, 1998; Knobel et al., 1999; Zito et al., 1999; Rodriguez et al., 1999; We generated transgenic mice in which red, green, yellow, or cyan fluorescent proteins (together termed Higashijima et al., 2000)
Proceedings of The National Academy of Sciences, 2004
We have devised and tested a new strategy for selectively delivering molecules to tumor cells. Ce... more We have devised and tested a new strategy for selectively delivering molecules to tumor cells. Cellular association of polyargininebased, cell-penetrating peptides (CPPs) is effectively blocked when they are fused to an inhibitory domain made up of negatively charged residues. We call these fusions activatable CPPs (ACPPs) because cleavage of the linker between the polycationic and polyanionic domains, typically by a protease, releases the CPP portion and its attached cargo to bind to and enter cells. Association with cultured cells typically increases 10-fold or more upon linker cleavage. In mice xenografted with human tumor cells secreting matrix metalloproteinases 2 and 9, ACPPs bearing a far-red-fluorescent cargo show in vivo contrast ratios of 2-3 and a 3.1-fold increase in standard uptake value for tumors relative to contralateral normal tissue or control peptides with scrambled linkers. Ex vivo slices of freshly resected human squamous cell carcinomas give similar or better contrast ratios. Because CPPs are known to import a wide variety of nonoptical contrast and therapeutic agents, ACPPs offer a general strategy toward imaging and treating disease processes associated with linker-cleaving activities such as extracellular proteases.
Integrative Biology, 2009
Activatable cell penetrating peptides (ACPPs) are novel in vivo targeting agents comprised of a p... more Activatable cell penetrating peptides (ACPPs) are novel in vivo targeting agents comprised of a polycationic cell penetrating peptide (CPP) connected via a cleavable linker to a neutralizing polyanion . Adsorption and uptake into cells are inhibited until the linker is proteolyzed1 -3 . An ACPP cleavable by matrix metalloproteinase-2 (MMP-2) in vitro was the first one demonstrated to work in a tumor model in vivo, but only HT-1080 xenografts and resected human squamous cell carcinomas were tested. Generality to other cancer types, in vivo selectivity of ACPPs for MMPs, and spatial resolution require further characterization. We now show that ACPPs can target many xenograft tumor models from different cancer sites, as well as a well thoroughly studied transgenic model of spontaneous breast cancer (mouse mammary tumor virus promoter driving polyoma middle T antigen, MMTV-PyMT). Pharmacological inhibitors and genetic knockouts indicate that current ACPPs are selective for MMP-2 and MMP-9 in the above in vivo models. In accord with the known local distribution of MMP activity, accumulation is strongest at the tumor-stromal interface in primary tumors and associated metastases, indicating better spatial resolution (<50 µm) than other currently available MMP-cleavable probes 4 . We also find that background uptake of ACPPs into normal tissues such as liver and kidney can be decreased by appending inert macromolecules of 30-50 KDa to the polyanionic inhibitory domain. Our results validate an approach that should generally deliver imaging agents and chemotherapeutics to sites of invasion, tumor-promoting inflammation, and metastasis.
Nature Neuroscience, 2002
A large body of evidence shows that molecular cues promote specific synapse formation by guiding ... more A large body of evidence shows that molecular cues promote specific synapse formation by guiding axons and by mediating their association with targets, but much less is known about the contribution of physical cues (such as mechanical constraints) to these processes. Here we used the peripheral motor system to investigate the latter issue. In living mice, we viewed individual motor axons bearing a fluorescent reporter, and mapped the cohort of muscle fibers that they innervated both before and after nerve damage. When gross trauma was minimized (by a nerve-crushing rather than nerve-cutting procedure), regenerating axons retraced their former pathways, bifurcated at original branch points, and formed neuromuscular junctions on the same fibers that they originally innervated. Axonal growth through tubes of non-neural cells seemed to account for this specificity, and specificity degraded when the tubes were cut. These results suggest that nonspecific guidance cues can be sufficient to generate specific synaptic circuitry.
Current Opinion in Neurobiology, 1996
Neuron, 2000
The first report on GFP expression in heterologous cells illustrated its use as a vital stain for... more The first report on GFP expression in heterologous cells illustrated its use as a vital stain for neurons (Chalfie Washington University School of Medicine St. Louis, Missouri 63110 et al., 1994). Since that time, neuroscience has been one of the greatest beneficiaries of GFP technology, and GFP has been used to facilitate the study of neuronal development and plasticity in transgenic worms, flies, fish, and mice (for example, Dynes and Ngai, 1998; Mur-Summary ray et al., 1998; van den Pol and Ghosh, 1998; Knobel et al., 1999; Zito et al., 1999; Rodriguez et al., 1999; We generated transgenic mice in which red, green, yellow, or cyan fluorescent proteins (together termed Higashijima et al., 2000)