Near-Infrared Fluorescence Imaging of Apoptotic Neuronal Cell Death in a Live Animal Model of Prion Disease

Lawson, Victoria; Haigh, Cathryn L.; Roberts, Blaine R.; Kenche, Vijaya B.; Klemm, Helen M; Masters, Colin L.; Collins, Steven J.; Barnham, Kevin J.; Drew, Simon C.

doi:10.1021/cn100068x

Cited by 24 publications

(13 citation statements)

References 32 publications

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“…Evidence of caspase activation has been detected in brain tissue obtained post-mortem from human Creutzfeldt-Jakob disease (CJD) patients (Jesionek-Kupnicka et al, 1997; Puig and Ferrer, 2001) and can be observed in the brains of live mice in the pre-terminal phases of prion disease (Lawson et al, 2010), with caspase-reactive aggregates observed inside neurons using the same active caspase label as in the current study (Drew et al, 2011). Furthermore, in GT1 and N2a cell models of prion infection, aggresomes associated with increased caspases 3 and 8 activity are formed when the proteosome is inhibited (Kristiansen et al, 2005).…”

Section: Discussionsupporting

confidence: 62%

Cytosolic caspases mediate mislocalised SOD2 depletion in an in vitro model of chronic prion infection

Sinclair

Lewis

Collins

et al. 2013

Disease Models &Amp; Mechanisms

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SUMMARYOxidative stress as a contributor to neuronal death during prion infection is supported by the fact that various oxidative damage markers accumulate in the brain during the course of this disease. The normal cellular substrate of the causative agent, the prion protein, is also linked with protective functions against oxidative stress. Our previous work has found that, in chronic prion infection, an apoptotic subpopulation of cells exhibit oxidative stress and the accumulation of oxidised lipid and protein aggregates with caspase recruitment. Given the likely failure of antioxidant defence mechanisms within apoptotic prion-infected cells, we aimed to investigate the role of the crucial antioxidant pathway components, superoxide dismutases (SOD) 1 and 2, in an in vitro model of chronic prion infection. Increased total SOD activity, attributable to SOD1, was found in the overall population coincident with a decrease in SOD2 protein levels. When apoptotic cells were separated from the total population, the induction of SOD activity in the infected apoptotic cells was lost, with activity reduced back to levels seen in mock-infected control cells. In addition, mitochondrial superoxide production was increased and mitochondrial numbers decreased in the infected apoptotic subpopulation. Furthermore, a pan-caspase probe colocalised with SOD2 outside of mitochondria within cytosolic aggregates in infected cells and inhibition of caspase activity was able to restore cellular levels of SOD2 in the whole unseparated infected population to those of mock-infected control cells. Our results suggest that prion propagation exacerbates an apoptotic pathway whereby mitochondrial dysfunction follows mislocalisation of SOD2 to cytosolic caspases, permitting its degradation. Eventually, cellular capacity to maintain oxidative homeostasis is overwhelmed, thus resulting in cell death.

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Section: Discussionsupporting

confidence: 62%

Cytosolic caspases mediate mislocalised SOD2 depletion in an in vitro model of chronic prion infection

Sinclair

Lewis

Collins

et al. 2013

Disease Models &Amp; Mechanisms

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“…[7][8][9][10] Cancer NIR molecular imaging relies greatly on the development of stable, highly specific and sensitive molecular probes. [11][12][13][14][15][16] Organic dyes such as indocyanine green have been used as nontargeted agents for optical imaging of cancer and have been used clinically for many years. 17,18 By combining these two molecules, we have developed a novel nitroimidazole indocyanine dye conjugate (2-nitroimidazole-ICG dye conjugate) for tumor-targeted hypoxia fluorescence tomography.…”

Section: Introductionmentioning

confidence: 99%

Targeting tumor hypoxia with 2-nitroimidazole-indocyanine green dye conjugates

Xu¹,

Zanganeh²,

Mohammad³

et al. 2013

J. Biomed. Opt

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Abstract. Tumor hypoxia is a major indicator of treatment resistance to chemotherapeutic drugs, and fluorescence optical tomography has tremendous potential to provide clinically useful, functional information by identifying tumor hypoxia. The synthesis of a 2-nitroimidazole-indocyanine green conjugate using a piperazine linker (piperazine-2-nitroimidazole-ICG) capable of robust fluorescent imaging of tumor hypoxia is described. In vivo mouse tumor imaging studies were completed and demonstrate an improved imaging capability of the new dye relative to an earlier version of the dye that was synthesized with an ethanolamine linker (ethanolamine-2-nitroimidazole-ICG). Mouse tumors located at imaging depths of 1.5 and 2.0 cm in a turbid medium were imaged at various time points after intravenous injection of the dyes. On average, the reconstructed maximum fluorescence concentration of the tumors injected with piperazine-2-nitroimidazole-ICG was twofold higher than that injected with ethanolamine-2-nitroimidazole-ICG within 3 h postinjection period and 1.6 to 1.7 times higher beyond 3 h postinjection. The untargeted bis-carboxylic acid ICG completely washed out after 3 h postinjection. Thus, the optimal window to assess tumor hypoxia is beyond 3 h postinjection. These findings were supported with fluorescence images of histological sections of tumor samples and an immunohistochemistry technique for identifying tumor hypoxia.

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“…We believe this study is the first to report development and in vivo validation of a novel PET imaging probe derived from the VAD-FMK peptide sequence. In general, the VAD-FMK sequence is known to be quite versatile and has been previously functionalized with fluorophores (39-42) and a radioisotope (33) for in vitro and certain preclinical applications. The probe developed here possesses all of the inherent advantages of a PET imaging agent, which include sensitivity, depth, and quantification (43, 44).…”

Section: Discussionmentioning

confidence: 99%

A Peptide-Based Positron Emission Tomography Probe for In Vivo Detection of Caspase Activity in Apoptotic Cells

Hight

Cheung

Nickels

et al. 2014

Clinical Cancer Research

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Purpose Apoptosis, or programmed cell death, can be leveraged as a surrogate measure of response to therapeutic interventions in medicine. Cysteine aspartic acid-specific proteases, or caspases, are essential determinants of apoptosis signaling cascades and represent promising targets for molecular imaging. Here, we report development and in vivo validation of [18F]4-fluorobenzylcarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone ([18F]FB-VAD-FMK), a novel peptide-based molecular probe suitable for quantification of caspase activity in vivo using positron emission tomography (PET). Experimental Design Supported by molecular modeling studies and subsequent in vitro assays suggesting probe feasibility the labeled pan-caspase inhibitory peptide, [18F]FB-VAD-FMK, was produced in high radiochemical yield and purity using a simple two-step, radiofluorination. The biodistribution of [18F]FB-VAD-FMK in normal tissue and its efficacy to predict response to molecularly targeted therapy in tumors was evaluated using microPET imaging of mouse models of human colorectal cancer (CRC). Results Accumulation of [18F]FB-VAD-FMK was found to agree with elevated caspase-3 activity in response to Aurora B kinase inhibition as well as a multi-drug regimen that combined an inhibitor of mutant BRAF and a dual PI3K/mTOR inhibitor in V600EBRAF colon cancer. In the latter setting, [18F]FB-VAD-FMK PET was also elevated in the tumors of cohorts that exhibited reduction in size. Conclusions These studies illuminate [18F]FB-VAD-FMK as a promising PET imaging probe to detect apoptosis in tumors and as a novel, potentially translatable biomarker for predicting response to personalized medicine.

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Near-Infrared Fluorescence Imaging of Apoptotic Neuronal Cell Death in a Live Animal Model of Prion Disease

Cited by 24 publications

References 32 publications

Cytosolic caspases mediate mislocalised SOD2 depletion in an in vitro model of chronic prion infection

Cytosolic caspases mediate mislocalised SOD2 depletion in an in vitro model of chronic prion infection

Targeting tumor hypoxia with 2-nitroimidazole-indocyanine green dye conjugates

A Peptide-Based Positron Emission Tomography Probe for In Vivo Detection of Caspase Activity in Apoptotic Cells

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