Publications by authors named "Cathleen Haase"

4 Publications

  • Page 1 of 1

L-type amino acid transporters LAT1 and LAT4 in cancer: uptake of 3-O-methyl-6-18F-fluoro-L-dopa in human adenocarcinoma and squamous cell carcinoma in vitro and in vivo.

J Nucl Med 2007 Dec;48(12):2063-71

Department of Radiopharmaceutical Biology, Institute of Radiopharmacy, Research Center Dresden-Rossendorf, Dresden, Germany.

Unlabelled: Expression of system L amino acid transporters (LAT) is strongly increased in many types of tumor cells. The purpose of this study was to demonstrate that (18)F-labeled amino acids, for example, 3-O-methyl-6-(18)F-fluoro-L-dopa ((18)F-OMFD), that accumulate in tumors via LAT represent an important class of imaging agents for visualization of tumors in vivo by PET.

Methods: (18)F-OMFD uptake kinetics, transport inhibition, and system L messenger RNA expression were studied in vitro in human adenocarcinoma (HT-29), squamous cell carcinoma (FaDu), macrophages (THP-1), and primary aortic endothelial cells (HAEC) and in vivo in the corresponding mouse tumor xenograft models.

Results: Uptake of (18)F-OMFD in all cell lines tested was mediated mainly by the sodium-independent high-capacity LAT. We found higher uptake in FaDu cells (V(max), 10.6 +/- 1.1 nmol/min x mg of cell protein) and in the corresponding FaDu tumor xenografts than in the other cells and corresponding xenograft models studied. Quantitative messenger RNA analysis revealed that tumor cells and xenografts have a higher expression of LAT1 than do HAEC and THP-1 macrophages. However, only in the FaDu tumor model did an increased (18)F-OMFD uptake seem to be explained by increased LAT expression. Furthermore, we demonstrated a high expression of LAT4, a recently identified LAT.

Conclusion: Our findings support the hypothesis that (18)F-OMFD is a tracer for visualization of tumor cells. (18)F-OMFD particularly seems to be a suitable tracer for diagnostic imaging of amino acid transport in poorly differentiated squamous cell head and neck carcinoma with increased LAT1 and LAT4 expression.
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http://dx.doi.org/10.2967/jnumed.107.043620DOI Listing
December 2007

Expression, purification and fluorine-18 radiolabeling of recombinant S100 proteins--potential probes for molecular imaging of receptor for advanced glycation endproducts (RAGE) in vivo.

Protein Expr Purif 2008 Feb 22;57(2):143-52. Epub 2007 Oct 22.

Department of Radiopharmaceutical Biology, Institute of Radiopharmacy, Research Center Dresden-Rossendorf, 01314 Dresden, Germany.

Data concerning the pathophysiological role of the interaction of circulating S100 proteins, a multigenic family of Ca(2+)-modulated proteins, with the receptor for advanced glycation endproducts (RAGE) in cardiovascular diseases, inflammatory processes, and tumorigenesis in vivo are scarce. One reason is the shortage of suitable radiotracer methods. We report a novel methodology using recombinant human S100A1, S100B, and S100A12 as potential probes for molecular imaging of this interaction. Therefore, human S100 proteins were cloned as GST fusion proteins in the bacterial expression vector pGEX-6P-1 and expressed in E. coli strain BL21. Purified recombinant human S100 proteins were radiolabeled with the positron emitter fluorine-18 ((18)F) by conjugation with N-succinimidyl-4-[(18)F]fluorobenzoate ([(18)F]SFB). The radiolabeled recombinant S100 proteins ((18)F-S100) were used in biodistribution experiments and small animal positron emission tomography (PET) studies in rats. The tissue-specific distribution of (18)F-S100 proteins in vivo correlated well with the anatomical localization of RAGE, e.g., in lungs and in the vascular system. These findings indicate circulating S100A1, S100B, and S100A12 proteins to be ligands for RAGE in rats in vivo. The approach allows the use of small animal PET and provides novel probes to delineate functional expression of RAGE under normal and pathophysiological conditions in rodent models of disease.
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http://dx.doi.org/10.1016/j.pep.2007.10.009DOI Listing
February 2008

Experimental hypoxia is a potent stimulus for radiotracer uptake in vitro: comparison of different tumor cells and primary endothelial cells.

Cancer Lett 2007 Aug 2;254(1):102-10. Epub 2007 Apr 2.

Institute of Radiopharmacy, Research Center Dresden-Rossendorf, Dresden, Germany.

Hypoxia causes upregulation of vascular endothelial growth factor (VEGF) which is a key regulator in tumor angiogenesis and essential for the proliferation of endothelial cells. Endothelial cells have been described to accumulate radiotracers like (18)F-FDG. However, the contribution of radiotracer uptake by endothelial cells to uptake measured in tumors by positron emission tomography (PET) is still unclear. In this study (18)F-FDG and (18)F-FMISO radiotracer uptake in various tumor and primary endothelial cells cultured at hypoxic conditions was investigated. Experimental hypoxia was confirmed by significant upregulation of VEGF mRNA. In comparison to normoxic conditions, cellular uptake of (18)F-FDG was significantly increased at hypoxic conditions in two of the tumor and all endothelial cells, whereas (18)F-FMISO uptake was only enhanced in tumor cell lines HT-29 and MCF-7. Our data showed a marked influence of experimental hypoxia on the metabolism and gene expression of tumor and endothelial cells in vitro. This indicates an important contribution of endothelial cells to (18)F-FDG radiotracer uptake in tumors and for the visualization of tumors by means of PET.
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http://dx.doi.org/10.1016/j.canlet.2007.02.016DOI Listing
August 2007

Effect of pseudophosphorylation and cross-linking by lipid peroxidation and advanced glycation end product precursors on tau aggregation and filament formation.

J Biol Chem 2007 Mar 1;282(10):6984-91. Epub 2006 Nov 1.

Nutritional Physiology Unit "Oskar Kellner," Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.

Accumulation of hyperphosphorylated Tau protein as paired helical filaments in pyramidal neurons is a major hallmark of Alzheimer disease. Besides hyperphosphorylation, other modifications of the Tau protein, such as cross-linking, are likely to contribute to the characteristic features of paired helical filaments, including their insolubility and resistance against proteolytic degradation. In this study, we have investigated whether the four reactive carbonyl compounds acrolein, malondialdehyde, glyoxal, and methylglyoxal accelerate the formation of Tau oligomers, thioflavin T-positive aggregates, and fibrils using wild-type and seven pseudophosphorylated mutant Tau proteins. Acrolein and methylglyoxal were the most reactive compounds followed by glyoxal and malondialdehyde in terms of formation of Tau dimers and higher molecular weight oligomers. Furthermore, acrolein and methylglyoxal induced the formation of thioflavin T-fluorescent aggregates in a triple pseudophosphorylation-mimicking mutant to a slightly higher degree than wild-type Tau. Analysis of the Tau aggregates by electron microscopy study showed that formation of fibrils using wild-type Tau and several Tau mutants could be observed with acrolein and methylglyoxal but not with glyoxal and malondialdehyde. Our results suggest that reactive carbonyl compounds, particularly methylglyoxal and acrolein, could accelerate tangle formation in vivo and that this process could be slightly accelerated, at least in the case of methylglyoxal and acrolein, by hyperphosphorylation. Interference with the formation or the reaction of these reactive carbonyl compounds could be a promising way of inhibiting tangle formation and neuronal dysfunction in Alzheimer disease and other tauopathies.
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http://dx.doi.org/10.1074/jbc.M609521200DOI Listing
March 2007