The Experts below are selected from a list of 4632 Experts worldwide ranked by ideXlab platform
Terence H. Rabbitts - One of the best experts on this subject based on the ideXlab platform.
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Cancer cell killing by target antigen engagement with engineered complementary intracellular antibody single domains fused to pro-caspase3
Scientific Reports, 2019Co-Authors: Jennifer S. Chambers, Tim Brend, Terence H. RabbittsAbstract:Many tumour causing proteins, such as those expressed after chromosomal translocations or from point mutations, are intracellular and are not enzymes per se amenable to conventional drug targeting. We previously demonstrated an approach (Antibody-antigen Interaction Dependent Apoptosis (AIDA)) whereby a single anti-β-galactosidase intracellular single chain Fv antibody fragment, fused to inactive Procaspase-3, induced auto-activation of caspase-3 after binding to the tetrameric β-galactosidase protein. We now demonstrate that co-expressing an anti-RAS heavy chain single VH domain, that binds to mutant RAS several thousand times more strongly than to wild type RAS, with a complementary light chain VL domain, caused programmed cell death (PCD) in mutant RAS expressing cells when each variable region is fused to Procaspase-3. The effect requires binding of both anti-RAS variable region fragments and is RAS-specific, producing a tri-molecular complex that auto-activates the caspase pathway leading to cell death. AIDA can be generally applicable for any target protein inside cells by involving appropriate pairs of antigen-specific intracellular antibodies.
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Cancer cell killing by target antigen engagement with engineered complementary intracellular antibody single domains fused to pro-caspase3
'Springer Science and Business Media LLC', 2019Co-Authors: Js Chambers, Brend T, Terence H. RabbittsAbstract:Many tumour causing proteins, such as those expressed after chromosomal translocations or from point mutations, are intracellular and are not enzymesandnbsp;per seandnbsp;amenable to conventional drug targeting. We previously demonstrated an approach (Antibody-antigenandnbsp;Interactionandnbsp;Dependentandnbsp;Apoptosis (AIDA)) whereby a single anti-andbeta;-galactosidase intracellular single chain Fv antibody fragment, fused to inactive Procaspase-3, induced auto-activation of caspase-3 after binding to the tetrameric andbeta;-galactosidase protein. We now demonstrate that co-expressing an anti-RAS heavy chain single VH domain, that binds to mutant RAS several thousand times more strongly than to wild type RAS, with a complementary light chain VL domain, caused programmed cell death (PCD) in mutant RAS expressing cells when each variable region is fused to Procaspase-3. The effect requires binding of both anti-RAS variable region fragments and is RAS-specific, producing a tri-molecular complex that auto-activates the caspase pathway leading to cell death. AIDA can be generally applicable for any target protein inside cells by involving appropriate pairs of antigen-specific intracellular antibodies.
Paul J. Hergenrother - One of the best experts on this subject based on the ideXlab platform.
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Immunohistochemical characterization of Procaspase-3 overexpression as a druggable target with PAC-1, a Procaspase-3 activator, in canine and human brain cancers
Frontiers in Oncology, 2019Co-Authors: Lisa J. Schlein, Bahaa Fadl-alla, Holly C. Pondenis, Stéphane Lezmi, Charles G. Eberhart, Amy K. Leblanc, Peter J. Dickinson, Paul J. HergenrotherAbstract:Gliomas and meningiomas are the most common brain neoplasms affecting both humans and canines, and identifying druggable targets conserved across multiple brain cancer histologies and comparative species could broadly improve treatment outcomes. While satisfactory cure rates for low grade, non-invasive brain cancers are achievable with conventional therapies including surgery and radiation, the management of non-resectable or recurrent brain tumors remains problematic and necessitates the discovery of novel therapies that could be accelerated through a comparative approach, such as the inclusion of pet dogs with naturally-occurring brain cancers. Evidence supports Procaspase-3 as a druggable brain cancer target with PAC-1, a pro-apoptotic, small molecule activator of Procaspase-3 that crosses the blood-brain barrier. Procaspase-3 is frequently overexpressed in malignantly transformed tissues and provides a preferential target for inducing cancer cell apoptosis. While preliminary evidence supports Procaspase-3 as a viable target in preclinical models, with PAC-1 demonstrating activity in rodent models and dogs with spontaneous brain tumors, the broader applicability of Procaspase-3 as a target in human brain cancers, as well as the comparability of Procaspase-3 expressions between differing species, requires further investigation. As such, a large-scale validation of Procaspase-3 as a druggable target was undertaken across 651 human and canine brain tumors. Relative to normal brain tissues, Procaspase-3 was overexpressed in histologically diverse cancerous brain tissues, supporting Procaspase-3 as a broad and conserved therapeutic target. Additionally, Procaspase-3 expressing glioma and meningioma cell lines were sensitive to the apoptotic effects of PAC-1 at biologically relevant exposures achievable in cancer patients. Importantly, the clinical relevance of Procaspase-3 as a potential prognostic variable was demonstrated in human astrocytomas of variable histologic grades and associated clinical outcomes, whereby tumoral Procaspase-3 expression was negatively correlated with survival; findings which suggest that PAC-1 might provide the greatest benefit for patients with the most guarded prognoses.
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overcoming resistance to targeted anticancer therapies through small molecule mediated mek degradation
Chemistry & Biology, 2018Co-Authors: Jessie Peh, Matthew W Boudreau, Hannah M Smith, Paul J. HergenrotherAbstract:Summary The discovery of mutant or fusion kinases that drive oncogenesis, and the subsequent approval of specific inhibitors for these enzymes, has been instrumental in the management of some cancers. However, acquired resistance remains a significant problem in the clinic, limiting the long-term effectiveness of most of these drugs. Here we demonstrate a general strategy to overcome this resistance through drug-induced MEK cleavage (via direct Procaspase-3 activation) combined with targeted kinase inhibition. This combination effect is shown to be general across diverse tumor histologies (melanoma, lung cancer, and leukemia) and driver mutations (mutant BRAF or EGFR, fusion kinases EML4-ALK and BCR-ABL). Caspase-3-mediated degradation of MEK kinases results in sustained pathway inhibition and substantially delayed or eliminated resistance in cancer cells in a manner far superior to combinations with MEK inhibitors. These data suggest the generality of drug-mediated MEK kinase cleavage as a therapeutic strategy to prevent resistance to targeted anticancer therapies.
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dual small molecule targeting of Procaspase 3 dramatically enhances zymogen activation and anticancer activity
Journal of the American Chemical Society, 2014Co-Authors: Rachel C Botham, Timothy M Fan, Luke B Borst, Levent Dirikolu, Paul J. HergenrotherAbstract:Combination anticancer therapy typically consists of drugs that target different biochemical pathways or those that act on different targets in the same pathway. Here we demonstrate a new concept in combination therapy, that of enzyme activation with two compounds that hit the same biological target, but through different mechanisms. Combinations of Procaspase-3 activators PAC-1 and 1541B show considerable synergy in activating Procaspase-3 in vitro, stimulate rapid and dramatic maturation of Procaspase-3 in multiple cancer cell lines, and powerfully induce caspase-dependent apoptotic death to a degree well exceeding the additive effect. In addition, the combination of PAC-1 and 1541B effectively reduces tumor burden in a murine lymphoma model at dosages for which the compounds alone have minimal or no effect. These data suggest the potential of PAC-1/1541B combinations for the treatment of cancer and, more broadly, demonstrate that differentially acting enzyme activators can potently synergize to give a ...
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Procaspase-3 Activation as an Anti-Cancer Strategy: Structure-Activity Relationship of Procaspase-Activating Compound 1 (PAC-1) and its Cellular Co-Localization with Caspase-3
Journal of Medicinal Chemistry, 2009Co-Authors: Quinn P. Peterson, Chris J. Novotny, David R. Goode, Ryan K. Totten, Paul J. HergenrotherAbstract:A goal of personalized medicine as applied to oncology is to identify compounds that exploit a defined molecular defect in a cancerous cell. A compound called Procaspase-activating compound 1 (PAC-1) was reported that enhances the activity of Procaspase-3 in vitro and induces apoptotic death in cancer cells in culture and in mouse xenograft models. Experimental evidence indicates that PAC-1 activates Procaspase-3 in vitro through chelation of inhibitory zinc ions. Described herein is the synthesis and biological activity of a family of PAC-1 derivatives where key functional groups have been systematically altered. Analysis of these compounds reveals a strong correlation between the in vitro Procaspase-3 activating effect and their ability to induce death in cancer cells in culture. Importantly, we also show that a fluorescently labeled version of PAC-1 co-localizes with sites of caspase-3 activity in cancer cells. The data presented herein further bolster the hypothesis that PAC-1 induces apoptosis in cancer cells through the direct activation of Procaspase-3, has implications for the design and discovery of next-generation Procaspase-3 activating compounds, and sheds light on the anti-apoptotic role of cellular zinc.
Shawn B. Bratton - One of the best experts on this subject based on the ideXlab platform.
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the apaf 1 Procaspase 9 apoptosome complex functions as a proteolytic based molecular timer
The EMBO Journal, 2009Co-Authors: Srinivas Malladi, Madhavi Challamalladi, Shawn B. BrattonAbstract:During stress‐induced apoptosis, the initiator caspase‐9 is activated by the Apaf‐1 apoptosome and must remain bound to retain significant catalytic activity. Nevertheless, in apoptotic cells the vast majority of processed caspase‐9 is paradoxically observed outside the complex. We show herein that apoptosome‐mediated cleavage of Procaspase‐9 occurs exclusively through a CARD‐displacement mechanism, so that unlike the effector Procaspase‐3, Procaspase‐9 cannot be processed by the apoptosome as a typical substrate. Indeed, Procaspase‐9 possessed higher affinity for the apoptosome and could displace the processed caspase‐9 from the complex, thereby facilitating a continuous cycle of Procaspase‐9 recruitment/activation, processing, and release from the complex. Owing to its rapid autocatalytic cleavage, however, Procaspase‐9 per se contributed little to the activation of Procaspase‐3. Thus, the Apaf‐1 apoptosome functions as a proteolytic‐based ‘molecular timer’, wherein the intracellular concentration of Procaspase‐9 sets the overall duration of the timer, Procaspase‐9 autoprocessing activates the timer, and the rate at which the processed caspase‐9 dissociates from the complex (and thus loses its capacity to activate Procaspase‐3) dictates how fast the timer ‘ticks’ over.
Wafik El Deiry - One of the best experts on this subject based on the ideXlab platform.
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deoxycholic acid dca causes ligand independent activation of epidermal growth factor receptor egfr and fas receptor in primary hepatocytes inhibition of egfr mitogen activated protein kinase signaling module enhances dca induced apoptosis
Molecular Biology of the Cell, 2001Co-Authors: Liang Qiao, Seema Gupta, Elaine Studer, Kevin Leach, Robert Mckinstry, Roy H Decker, Rakesh C Kukreja, Kristoffer Valerie, Prakash S Nagarkatti, Wafik El DeiryAbstract:Previous studies have argued that enhanced activity of the epidermal growth factor receptor (EGFR) and the mitogen-activated protein kinase (MAPK) pathway can promote tumor cell survival in response to cytotoxic insults. In this study, we examined the impact of MAPK signaling on the survival of primary hepatocytes exposed to low concentrations of deoxycholic acid (DCA, 50 microM). Treatment of hepatocytes with DCA caused MAPK activation, which was dependent upon ligand independent activation of EGFR, and downstream signaling through Ras and PI(3) kinase. Neither inhibition of MAPK signaling alone by MEK1/2 inhibitors, nor exposure to DCA alone, enhanced basal hepatocyte apoptosis, whereas inhibition of DCA-induced MAPK activation caused approximately 25% apoptosis within 6 h. Similar data were also obtained when either dominant negative EGFR-CD533 or dominant negative Ras N17 were used to block MAPK activation. DCA-induced apoptosis correlated with sequential cleavage of Procaspase 8, BID, Procaspase 9, and Procaspase 3. Inhibition of MAPK potentiated bile acid-induced apoptosis in hepatocytes with mutant FAS-ligand, but did not enhance in hepatocytes that were null for FAS receptor expression. These data argues that DCA is causing ligand independent activation of the FAS receptor to stimulate an apoptotic response, which is counteracted by enhanced ligand-independent EGFR/MAPK signaling. In agreement with FAS-mediated cell killing, inhibition of caspase function with the use of dominant negative Fas-associated protein with death domain, a caspase 8 inhibitor (Ile-Glu-Thr-Asp-p-nitroanilide [IETD]) or dominant negative Procaspase 8 blocked the potentiation of bile acid-induced apoptosis. Inhibition of bile acid-induced MAPK signaling enhanced the cleavage of BID and release of cytochrome c from mitochondria, which were all blocked by IETD. Despite activation of caspase 8, expression of dominant negative Procaspase 9 blocked Procaspase 3 cleavage and the potentiation of DCA-induced apoptosis. Treatment of hepatocytes with DCA transiently increased expression of the caspase 8 inhibitor proteins c-FLIP-(S) and c-FLIP-(L) that were reduced by inhibition of MAPK or PI(3) kinase. Constitutive overexpression of c-FLIP-(s) abolished the potentiation of bile acid-induced apoptosis. Collectively, our data argue that loss of DCA-induced EGFR/Ras/MAPK pathway function potentiates DCA-stimulated FAS-induced hepatocyte cell death via a reduction in the expression of c-FLIP isoforms.
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deoxycholic acid dca causes ligand independent activation of epidermal growth factor receptor egfr and fas receptor in primary hepatocytes inhibition of egfr mitogen activated protein kinase signaling module enhances dca induced apoptosis
Molecular Biology of the Cell, 2001Co-Authors: Liang Qiao, Seema Gupta, Elaine Studer, Kevin Leach, Robert Mckinstry, Roy H Decker, Rakesh C Kukreja, Kristoffer Valerie, Prakash S Nagarkatti, Wafik El DeiryAbstract:: Previous studies have argued that enhanced activity of the epidermal growth factor receptor (EGFR) and the mitogen-activated protein kinase (MAPK) pathway can promote tumor cell survival in response to cytotoxic insults. In this study, we examined the impact of MAPK signaling on the survival of primary hepatocytes exposed to low concentrations of deoxycholic acid (DCA, 50 microM). Treatment of hepatocytes with DCA caused MAPK activation, which was dependent upon ligand independent activation of EGFR, and downstream signaling through Ras and PI(3) kinase. Neither inhibition of MAPK signaling alone by MEK1/2 inhibitors, nor exposure to DCA alone, enhanced basal hepatocyte apoptosis, whereas inhibition of DCA-induced MAPK activation caused approximately 25% apoptosis within 6 h. Similar data were also obtained when either dominant negative EGFR-CD533 or dominant negative Ras N17 were used to block MAPK activation. DCA-induced apoptosis correlated with sequential cleavage of Procaspase 8, BID, Procaspase 9, and Procaspase 3. Inhibition of MAPK potentiated bile acid-induced apoptosis in hepatocytes with mutant FAS-ligand, but did not enhance in hepatocytes that were null for FAS receptor expression. These data argues that DCA is causing ligand independent activation of the FAS receptor to stimulate an apoptotic response, which is counteracted by enhanced ligand-independent EGFR/MAPK signaling. In agreement with FAS-mediated cell killing, inhibition of caspase function with the use of dominant negative Fas-associated protein with death domain, a caspase 8 inhibitor (Ile-Glu-Thr-Asp-p-nitroanilide [IETD]) or dominant negative Procaspase 8 blocked the potentiation of bile acid-induced apoptosis. Inhibition of bile acid-induced MAPK signaling enhanced the cleavage of BID and release of cytochrome c from mitochondria, which were all blocked by IETD. Despite activation of caspase 8, expression of dominant negative Procaspase 9 blocked Procaspase 3 cleavage and the potentiation of DCA-induced apoptosis. Treatment of hepatocytes with DCA transiently increased expression of the caspase 8 inhibitor proteins c-FLIP-(S) and c-FLIP-(L) that were reduced by inhibition of MAPK or PI(3) kinase. Constitutive overexpression of c-FLIP-(s) abolished the potentiation of bile acid-induced apoptosis. Collectively, our data argue that loss of DCA-induced EGFR/Ras/MAPK pathway function potentiates DCA-stimulated FAS-induced hepatocyte cell death via a reduction in the expression of c-FLIP isoforms.
Jennifer S. Chambers - One of the best experts on this subject based on the ideXlab platform.
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Cancer cell killing by target antigen engagement with engineered complementary intracellular antibody single domains fused to pro-caspase3
Scientific Reports, 2019Co-Authors: Jennifer S. Chambers, Tim Brend, Terence H. RabbittsAbstract:Many tumour causing proteins, such as those expressed after chromosomal translocations or from point mutations, are intracellular and are not enzymes per se amenable to conventional drug targeting. We previously demonstrated an approach (Antibody-antigen Interaction Dependent Apoptosis (AIDA)) whereby a single anti-β-galactosidase intracellular single chain Fv antibody fragment, fused to inactive Procaspase-3, induced auto-activation of caspase-3 after binding to the tetrameric β-galactosidase protein. We now demonstrate that co-expressing an anti-RAS heavy chain single VH domain, that binds to mutant RAS several thousand times more strongly than to wild type RAS, with a complementary light chain VL domain, caused programmed cell death (PCD) in mutant RAS expressing cells when each variable region is fused to Procaspase-3. The effect requires binding of both anti-RAS variable region fragments and is RAS-specific, producing a tri-molecular complex that auto-activates the caspase pathway leading to cell death. AIDA can be generally applicable for any target protein inside cells by involving appropriate pairs of antigen-specific intracellular antibodies.