Papers by Christel Vangestel
The urokinase plasminogen activator (uPA) system is a proteolytic cascade involved in tumor invas... more The urokinase plasminogen activator (uPA) system is a proteolytic cascade involved in tumor invasion and metastasis. uPA and its inhibitor PAI-1 are described as biomarkers for breast cancer with the highest level of evidence. The present study describes the synthesis and first in vivo application of an activity based uPA PET probe. Methods: Based on the design of a small irreversible and selective uPA inhibitor we developed an 18 F-labeled activity based probe for uPA imaging. Human uPA expressing MDA-MB-231-luc2-GFP cells were inoculated in the mammary fat pads of nude mice and treated with the probe once tumors reached a volume of 150 mm 3 . Scans were performed at 0.25, 0.75, 1.5, 4 and 6 h post injection. To evaluate tumor uptake in vivo and ex vivo data were gathered. Biodistribution data of the organs and tissues of interest were collected at all time points. Due to a relatively low tumor uptake, probe stability was further evaluated. Results: The uPA targeting PET tracer was produced in high purity and with good specific radioactivity. In vivo PET data showed a maximum tumor uptake of 2,51 ± 0,32 %ID/g at 4 h p.i. A significant correlation between in vivo and ex vivo tumor uptake calculation was found (R = 0.75; p b 0.01). Due to a high blood signal at all time points, probe stability was further examined revealing high plasma protein binding and low plasma stability. Conclusions: In vivo and ex vivo results clearly demonstrate that uPA expressing tumors can be detected with non-invasive PET imaging. Stability tests suggest that further optimization is needed to provide a better tumor-to-background contrast.
Forcing cancer cells to commit suicide
Cancer biotherapy & radiopharmaceuticals, 2009
Apoptosis plays a crucial role in the normal development, homeostasis of multicellular organisms,... more Apoptosis plays a crucial role in the normal development, homeostasis of multicellular organisms, carcinogenic process, and response of cancer cells to anticancer drugs. It is a genetically strictly regulated process, controlled by the balance between pro- and antiapoptotic proteins. Resistance to standard chemotherapeutics also seems to be an apoptosis-related process due to failure to activate the apoptotic machinery. Hence, the molecular pathways (extrinsic and intrinsic) regulating the apoptotic process are attractive targets for potential therapeutic intervention. The goal of proapoptotic drugs is to selectively induce apoptosis in the tumor cell while leaving healthy cells unharmed. Several proapoptotic receptor agonists have recently been developed, activating selectively the extrinsic pathway, and give promising results. Targets for the intrinsic pathway include the Bcl-2 family proteins, the inhibitor of apoptosis proteins, the p53 pathway, and many others. However, several...
Histology and histopathology, 2011
The aim of this study was to assess the expression pattern and prognostic value of the high affin... more The aim of this study was to assess the expression pattern and prognostic value of the high affinity glucose transporters GLUT-1, 3, 4, 8 and 9, SGLT-1 and of hexokinases (HK) I, II and III in squamous cell carcinoma of the tonsil and mobile tongue (TTSCC) by means of immunohistochemistry. Seventy-one consecutive patients suffering from TTSCC were included. The intensity and amount of positive tumour cells in the immunoreaction (histology score (H-score)) for GLUT-1, 3, 4, 8 and 9 as well as for HK-I, II and III were assessed independently by two experienced observers, blinded to the clinical results. H-scores as well as clinical variables were related to patient outcome. Median follow-up time was 49 months (range 1-123 months). Mean H-scores for GLUT expression in decreasing order of magnitude were respectively 10.99 for GLUT-1 (sd 3.9), 5.7 for GLUT-8 (sd 4.0), 5.4 for GLUT-3 (sd 3.7), 1.0 for GLUT-4 (sd 2.0), 1.1 (sd 1.3) for SGLT-1, and 0.4 for GLUT-9 (sd 0.6); GLUT-1 > GLUT-...
European Journal of Nuclear Medicine and Molecular Imaging, 2009
Tissue hypoxia results from an inadequate supply of oxygen (O2) that compromises biological funct... more Tissue hypoxia results from an inadequate supply of oxygen (O2) that compromises biological functions. Structural and functional abnormalities of the tumour vasculature together with altered diffusion conditions inside the tumour seem to be the main causes of tumour hypoxia. Evidence from experimental and clinical studies points to a role for tumour hypoxia in tumour propagation, resistance to therapy and malignant
The urokinase plasminogen activator (uPA) system is a proteolytic cascade involved in tumor invas... more The urokinase plasminogen activator (uPA) system is a proteolytic cascade involved in tumor invasion and metastasis. uPA and its inhibitor PAI-1 are described as biomarkers for breast cancer with the highest level of evidence. The present study describes the synthesis and first in vivo application of an activity based uPA PET probe. Methods: Based on the design of a small irreversible and selective uPA inhibitor we developed an 18 F-labeled activity based probe for uPA imaging. Human uPA expressing MDA-MB-231-luc2-GFP cells were inoculated in the mammary fat pads of nude mice and treated with the probe once tumors reached a volume of 150 mm 3 . Scans were performed at 0.25, 0.75, 1.5, 4 and 6 h post injection. To evaluate tumor uptake in vivo and ex vivo data were gathered. Biodistribution data of the organs and tissues of interest were collected at all time points. Due to a relatively low tumor uptake, probe stability was further evaluated. Results: The uPA targeting PET tracer was produced in high purity and with good specific radioactivity. In vivo PET data showed a maximum tumor uptake of 2,51 ± 0,32 %ID/g at 4 h p.i. A significant correlation between in vivo and ex vivo tumor uptake calculation was found (R = 0.75; p b 0.01). Due to a high blood signal at all time points, probe stability was further examined revealing high plasma protein binding and low plasma stability. Conclusions: In vivo and ex vivo results clearly demonstrate that uPA expressing tumors can be detected with non-invasive PET imaging. Stability tests suggest that further optimization is needed to provide a better tumor-to-background contrast.
Journal of Nuclear Medicine, 2011
His-annexin A5 micro-SPECT demonstrates increased antitumor activity of irinotecan during the tra... more His-annexin A5 micro-SPECT demonstrates increased antitumor activity of irinotecan during the transient vascular normalization period caused by bevacizumab. Our data outline the importance of timing of combined anti-VEGF treatment with chemotherapy.
Cancer Biotherapy & Radiopharmaceuticals, 2010
Tumor cells are characterized by an increased rate of glucose consumption and glycolysis. This in... more Tumor cells are characterized by an increased rate of glucose consumption and glycolysis. This increased glucose consumption leads to tumor acidification, which represents a major obstacle for several therapeutic strategies. Tumor cells have adapted to this acidification by upregulation of several H þ -extruding transporter systems and proteins to cope with this compromised situation. One of these proteins is carbonic anhydrase IX (CA IX), which catalyzes the reversible hydration of carbon dioxide to carbonic acid outside the cell, leading to an acidic extracellular pH and a physiological intracellular pH. The aim of this article was to study semiquantitatively the expression of CA IX in non-small cell lung cancer (NSCLC) and to assess the existence of a possible relationship between CA IX expression and tumor FDG uptake, reflecting glucose metabolism. The levels and the extent of CA IX expression were estimated in immunohistochemical stained, formalin-fixed, paraffin-embedded tissue samples from 18 patients with NSCLC and compared with FDG uptake in FDG-PET imaging. We found a statistically significant correlation between CA IX Hscores and SUVmax and SUVmean values of the primary tumor. This relationship provides indirect evidence for cotranscription of glucose transporters and hexokinases that drive tumor hyperglycolysis and for CA IX governed by hypoxia-inducible factor-1 and suggests that, in the future, it may be possible to identify NSCLC patients who are most likely to benefit from CA IX targeting therapy on the basis of FDG-PET imaging.
Forcing Cancer Cells to Commit Suicide
Cancer Biotherapy & Radiopharmaceuticals, 2009
Apoptosis plays a crucial role in the normal development, homeostasis of multicellular organisms,... more Apoptosis plays a crucial role in the normal development, homeostasis of multicellular organisms, carcinogenic process, and response of cancer cells to anticancer drugs. It is a genetically strictly regulated process, controlled by the balance between pro- and antiapoptotic proteins. Resistance to standard chemotherapeutics also seems to be an apoptosis-related process due to failure to activate the apoptotic machinery. Hence, the molecular pathways (extrinsic and intrinsic) regulating the apoptotic process are attractive targets for potential therapeutic intervention. The goal of proapoptotic drugs is to selectively induce apoptosis in the tumor cell while leaving healthy cells unharmed. Several proapoptotic receptor agonists have recently been developed, activating selectively the extrinsic pathway, and give promising results. Targets for the intrinsic pathway include the Bcl-2 family proteins, the inhibitor of apoptosis proteins, the p53 pathway, and many others. However, several studies have implicated that using monotherapy will probably not be sufficient to sensitize or induce apoptosis in all tumor cells. Most promising results, in terms of killing the tumor cell, will be achieved by the combination of various therapeutic strategies. In this review, promising apoptosis-inducing anticancer therapies are summarized.
![Research paper thumbnail of In vitro and in vivo evaluation of [99mTc]-labeled tricarbonyl His-annexin A5 as an imaging agent for the detection of phosphatidylserine-expressing cells](https://attachments.academia-assets.com/46683314/thumbnails/1.jpg)
Nuclear medicine and biology, 2010
Introduction: Apoptosis is one of the mechanisms behind successful chemotherapy and radiation tre... more Introduction: Apoptosis is one of the mechanisms behind successful chemotherapy and radiation treatment. Radiolabeled annexin A5 has been demonstrated to be a successful tool in the detection of apoptosis following chemotherapy in vivo. Methods: His-tagged annexin A5 was labeled with [ 99m Tc]-tricarbonyl and evaluated as apoptosis imaging radiotracer in vitro and in vivo. The binding of the radiotracer was evaluated in Colo205 cells stimulated with 5-FU (1 mM) for 4 and 24 h, and confirmed by flow cytometry. Biodistribution and dosimetric studies were performed in healthy nude mice (n=5) via planar scintigraphy. [ 99m Tc]-(CO) 3 His-annexin A5 was also evaluated for in vivo imaging of spontaneous apoptosis in Colo205-bearing mice (n=12). Results: The labeling procedure yielded a compound with 95-99% radiochemical purity and good in vitro stability. In vitro binding experiments indicated that the radiotracer retained its PS-binding activity. [ 99m Tc]-(CO) 3 His-annexin A5 rapidly cleared from the blood and predominantly accumulated in the kidneys. Absorbed dose (per organ) was found to be 116±64 μGy/MBq for the kidneys and 10.38±0.50 μGy/MBq for the liver. The effective dose was 7.00±0.28 μSv/MBq. Spontaneous apoptosis in Colo205-bearing mice was visualised by [ 99m Tc]-(CO) 3 His-annexin A5 SPECT and correlated well with caspase-3 immunostaining (R=0.867, Pb.01). Conclusion: [ 99m Tc]-(CO) 3 His-annexin A5 may be a useful novel radioligand for the in vivo detection of cell death associated with PS expression. A simple, noninvasive way of detecting apoptosis in vivo could have many applications including a better understanding of the extent and timing of apoptosis in response to cancer therapies and assessment of early tumor response.
Cancer Biotherapy …, 2009
Erythropoietin (EPO) has been used to correct cancer-related anemia and to improve tumor hypoxia,... more Erythropoietin (EPO) has been used to correct cancer-related anemia and to improve tumor hypoxia, which both adversely affect the clinical condition of cancer patients and response to radiotherapy. Data available on the effects of EPO treatment in cancer are, however, conflicting. Several clinical studies investigating the influence of EPO treatment have given contradictory results as to whether or not this treatment positively influences survival. In light of these conflicting results, we studied the effects of EPO treatment either alone or in combination with radiotherapy on tumor oxygenation and on the expression pattern of several proteins related to tumor metabolism, survival, and spread in a rat colorectal cancer model. We found a statistically significant upregulation of hexokinase I, N-cadherin, and glucose transporter 3 when EPO treatment was combined with radiotherapy. Because these three proteins have distinct functions in protecting the cell in compromised conditions, these results indicate a detrimental role for the combination of EPO treatment and radiotherapy through the stimulation of tumor-cell metabolism, inhibition of apoptosis, and stimulation of tumor spread and seem to indicate that recombinant human EPO treatment negatively modulates radiotherapy efficacy.
Molecular imaging, 2011
In this review, data on noninvasive imaging of apoptosis in oncology are reviewed. Imaging data a... more In this review, data on noninvasive imaging of apoptosis in oncology are reviewed. Imaging data available are presented in order of occurrence in time of enzymatic and morphologic events occurring during apoptosis. Available studies suggest that various radiopharmaceutical probes bear great potential for apoptosis imaging by means of positron emission tomography and single-photon emission computed tomography (SPECT). However, for several of these probes, thorough toxicologic studies are required before they can be applied in clinical studies. Both preclinical and clinical studies support the notion that 99mTc-hydrazinonicotinamide-annexin A5 and SPECT allow for noninvasive, repetitive, quantitative apoptosis imaging and for assessing tumor response as early as 24 hours following treatment instigation. Bioluminescence imaging and near-infrared fluorescence imaging have shown great potential in small-animal imaging, but their usefulness for in vivo imaging in humans is limited to stru...
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Papers by Christel Vangestel