Potassium channels as tumour markers

AbstractAn increasing number of ion channels are being found to be causally involved in diseases, giving rise to the new field of “channelopathies”. Cancer is no exception, and several ion channels have been linked to tumour progression. Among them is the potassium channel EAG (Ether-a-go-go). Over 75% of tumours have been tested positive using a monoclonal antibody specific for EAG, while inhibition of this channel decreased the proliferation of EAG expressing cells. The inhibition of EAG is accomplished using RNA interference, functional anti-EAG1 antibodies, or (unspecific) EAG channel blockers. Fluorescently labelled recombinant Fab fragments recognizing EAG allow the distribution of EAG to be visualized in an in vivo mouse tumour model

Evaluation of Antibody Directed Enzyme Prodrug Therapy-concept in mammary carcinoma- and lymphoma-mouse model

Ziel dieser Arbeit war es ein neues Therapiekonzept Antibody Directed Enzyme Prodrug Therapy (ADEPT) in Tieren zu evaluieren. Damit sollte eine höhere Spezifität und Selektivität in der Behandlung von Tumoren erreicht werden. Dabei wurden ein orthotopes Mammakarzinom- mit MDA-MB-231-Tumorzellen in weiblichen SCID-Mäusen und ein syngenes Lymphom-Modell mit hochmalignem B-Zell Non-Hodgkin-Lymphom in Balb/c-Mäusen unter Verwendung von murinen A20-Zellen untersucht. Es wurden die Antikörper anti-uPAR und anti-CD19 für den Transport von β-D-Galaktosidase an den Tumor verwendet. Um die ADEPT zu evaluieren wurden die nichtinvasiven Methoden fpVCT und eXplore Optix angewendet. Anti-uPAR*β-D-Galaktosidase bindet sowohl in vitro als auch in vivo an MDA-MB-231-Tumorzellen. Dabei wurde jeweils eine Enzymaktivität nachgewiesen. 48 Stunden nach der anti-uPAR Applikation sank die Menge des freien Antikörpers im Serum von tumortragenden Mäusen derart, dass nach dieser Zeit das Prodrug i.v. verabreicht werden konnte. Die Therapie im Mammakarzinom-Modell wurde in zwei Zyklen durchgeführt. Dabei erfolgte zunächst eine anti-uPAR*β-D-Galaktosidase Applikation, die von drei Prodrug-Applikationen in 48-stündigen Intervallen ergänzt wurde. Die Tumorvolumina wurden mittel fpVCT vor und nach dem ersten und zweiten Therapiezyklus bestimmt. Die ADEPT verursachte eine Hemmung des Mammakarzinomwachstums bei therapierten Mäusen im Vergleich zu den Kontrolltieren, bei denen die Tumorwachstumsraten um den Faktor 1,7 höher lagen. Im Lymphom-Modell band anti-CD19*β-D-Galaktosidase in vitro und in vivo an die A20-Tumorzellen des Balb/c-Mausmodells. Hier konnte bereits nach 24 h das Prodrug i.v. verabreicht werden. Die Therapie wurde ebenfalls wie beim Mammakarzinom-Modell in zwei Zyklen durchgeführt, jeweils eine anti-CD19*β-D-Galaktosidase Applikation und drei Prodruganwendungen in einem 24-stündigem Intervall. Die Lymphomvolumina wurden mittels fpVCT am Beginn und Ende der Therapie untersucht. Die ADEPT verursachte eine Hemmung des Lymphomwachstums bei den therapierten Mäusen im Vergleich zu den Kontrolltieren, wo die Lymphomwachstums-raten um den Faktor 3,6 höher lagen. Es wurde gezeigt, dass die ADEPT-Therapie in beiden Modellen in vivo eine Hemmung des Tumor- bzw. Lymphomwachstums bewirkt. Das ADEPT-Konzept bietet eine potentielle Therapie mit größerer Selektivität und eventuell weniger Nebenwirkungen für Krebserkrankungen

Morphologic Changes of Mammary Carcinomas in Mice over Time as Monitored by Flat-Panel Detector Volume Computed Tomography1

Noninvasive methods are strongly needed to detect and quantify not only tumor growth in murine tumor models but also the development of vascularization and necrosis within tumors. This study investigates the use of a new imaging technique, flat-panel detector volume computed tomography (fpVCT), to monitor in vivo tumor progression and structural changes within tumors of two murine carcinoma models. After tumor cell inoculation, single fpVCT scans of the entire mice were performed at different time points. The acquired isotropic, high-resolution volume data sets enable an accurate real-time assessment and precise measurements of tumor volumes. Spreading of contrast agent-containing blood vessels around and within the tumors was clearly visible over time. Furthermore, fpVCT permits the identification of differences in the uptake of contrast media within tumors, thus delineating necrosis, tumor tissues, and blood vessels. Classification of tumor tissues based on the decomposition of the underlying mixture distribution of tissue-related Hounsfield units allowed the quantitative acquisition of necrotic tissues at each time point. Morphologic alterations of the tumor depicted by fpVCT were confirmed by histopathologic examination. Concluding, our data show that fpVCT may be highly suitable for the noninvasive evaluation of tumor responses to anticancer therapies during the course of the disease

Semiautomatic Landmark-Based Two-Dimensional—Three-Dimensional Image Fusion in Living Mice: Correlation of Near-Infrared Fluorescence Imaging of Cy5.5-Labeled Antibodies with Flat-Panel Volume Computed Tomography

Connecting fluorescence signals with anatomic structures enhances our ability to monitor biologic processes in mice. Here, we present a semiautomated approach to correlate two-dimensional (2D) noninvasive near-infrared fluorescence (NIRF) imaging with three-dimensional (3D), high-resolution, flat-panel volume computed tomography (fpVCT). We developed an algorithm to colocalize fluorescence signals of NIRF-labeled antibodies directed against matriptase and urokinase plasminogen activator receptor (uPAR) to orthotopic carcinomas in mice visualized by fpVCT. For this purpose, mice were anesthetized and fixed on a multimodality animal bed containing fiducial markers filled with iodine-containing contrast agent and fluorescent dye. After intravenous administration of contrast agent and Cy5.5-labeled antibodies, NIRF and fpVCT images were obtained, without repositioning the mice. Binding of Cy5.5-labeled matriptase-specific antibody to pancreatic tumors and Cy5.5-labeled uPAR-specific antibody to mammary carcinomas was assessed by time-domain NIRF imaging measuring the location of fluorescence intensity and its lifetime. In summary, we developed a novel 2D-3D registration technique for image fusion with NIRF imaging and fpVCT to provide complementary information in tumor models on the in vivo association of functional information with anatomic structures. The combination of fpVCT with NIRF imaging will now allow targeted and effective monitoring of preclinical tumor therapies

Flat-Panel Detector-Based Volume Computed Tomography: A Novel 3D Imaging Technique to Monitor Osteolytic Bone Lesions in a Mouse Tumor Metastasis Model1

Skeletal metastasis is an important cause of mortality in patients with breast cancer. Hence, animal models, in combination with various imaging techniques, are in high demand for preclinical assessment of novel therapies. We evaluated the applicability of flat-panel volume computed tomography (fpVCT) to noninvasive detection of osteolytic bone metastases that develop in severe immunodeficient mice after intracardial injection of MDA-MB-231 breast cancer cells. A single fpVCT scan at 200-µm isotropic resolution was employed to detect osteolysis within the entire skeleton. Osteolytic lesions identified by fpVCT correlated with Faxitron X-ray analysis and were subsequently confirmed by histopathological examination. Isotropic three-dimensional image data sets obtained by fpVCT were the basis for the precise visualization of the extent of the lesion within the cortical bone and for the measurement of bone loss. Furthermore, fpVCT imaging allows continuous monitoring of growth kinetics for each metastatic site and visualization of lesions in more complex regions of the skeleton, such as the skull. Our findings suggest that fpVCT is a powerful tool that can be used to monitor the occurrence and progression of osteolytic lesions in vivo and can be further developed to monitor responses to antimetastatic therapies over the course of the disease