Dominik Hüster

Malignant tumors with high glucose metabolic rates accumulate [18F]-fluorodeoxyglucose (FDG), a positron emitting tracer. The aim of this study was to evaluate FDG positron emission tomography (PET) for detection and staging of human cholangiocarcinoma (CC). Patients with adenocarcinoma of the biliary tree (n = 26), with benign lesions of the bile ducts (n = 8), and 20 control patients underwent FDG-PET (370 MBq [18F]-FDG, Siemens ECAT EXACT HR(+)). In a blinded fashion, 4 independent experts evaluated the PET scans visually and semiquantitatively using the standardized uptake value and a tumor/non-tumor ratio. All adenocarcinomas and benign lesions (sclerosing cholangitis, bile duct adenoma, Caroli's disease) were histologically proven and imaged by magnetic resonance imaging and endoscopic retrograde cholangioscopy. True-positive PET scans were obtained in 24 of 26 CC and false-negative scans in the other 2 (sensitivity 92.3%). The PET scan was true-negative in 18 of 20 controls and in all 8 benign biliary lesions (specificity 92.9%). Visual and semiquantitative evaluation using tumor/non-tumor ratios were equally accurate (accuracy 92.6%) whereas evaluation by standardized uptake value revealed lower accuracy (P <.05). Regional or hepatoduodenal lymph node metastases were detected with PET in only 2 of 15 cases whereas distant metastases (peritoneal carcinomatosis, pulmonary metastases) were diagnosed in 7 of 10 cases. In conclusion, PET is highly sensitive and specific for the detection and localization of CC. It can be helpful for diagnosis of distant metastases but is not suitable for detection of regional lymph node metastases.

Copper is essential for human physiology, but in excess it causes the severe metabolic disorder Wilson disease. Elevated copper is thought to induce pathological changes in tissues by stimulating the production of reactive oxygen species that damage multiple cell targets. To better understand the molecular basis of this disease, we performed genome-wide mRNA profiling as well as protein and metabolite analysis for Atp7b-/- mice, an animal model of Wilson disease. We found that at the presymptomatic stages of the disease, copper-induced changes are inconsistent with widespread radical-mediated damage, which is likely due to the sequestration of cytosolic copper by metallothioneins that are markedly up-regulated in Atp7b-/- livers. Instead, copper selectively up-regulates molecular machinery associated with the cell cycle and chromatin structure and down-regulates lipid metabolism, particularly cholesterol biosynthesis. Specific changes in the transcriptome are accompanied by distinct metabolic changes. Biochemical and mass spectroscopy measurements revealed a 3.6-fold decrease of very low density lipoprotein cholesterol in serum and a 33% decrease of liver cholesterol, indicative of a marked decrease in cholesterol biosynthesis. Consistent with low cholesterol levels, the amount of activated sterol regulatory-binding protein 2 (SREBP-2) is increased in Atp7b-/- nuclei. However, the SREBP-2 target genes are dysregulated suggesting that elevated copper alters SREBP-2 function rather than its processing or re-localization. Thus, in Atp7b-/- mice elevated copper affects specific cellular targets at the transcription and/or translation levels and has distinct effects on liver metabolic function, prior to appearance of histopathological changes. The identification of the network of specific copper-responsive targets facilitates further mechanistic analysis of human disorders of copper misbalance. Copper is essential for human physiology, but in excess it causes the severe metabolic disorder Wilson disease. Elevated copper is thought to induce pathological changes in tissues by stimulating the production of reactive oxygen species that damage multiple cell targets. To better understand the molecular basis of this disease, we performed genome-wide mRNA profiling as well as protein and metabolite analysis for Atp7b-/- mice, an animal model of Wilson disease. We found that at the presymptomatic stages of the disease, copper-induced changes are inconsistent with widespread radical-mediated damage, which is likely due to the sequestration of cytosolic copper by metallothioneins that are markedly up-regulated in Atp7b-/- livers. Instead, copper selectively up-regulates molecular machinery associated with the cell cycle and chromatin structure and down-regulates lipid metabolism, particularly cholesterol biosynthesis. Specific changes in the transcriptome are accompanied by distinct metabolic changes. Biochemical and mass spectroscopy measurements revealed a 3.6-fold decrease of very low density lipoprotein cholesterol in serum and a 33% decrease of liver cholesterol, indicative of a marked decrease in cholesterol biosynthesis. Consistent with low cholesterol levels, the amount of activated sterol regulatory-binding protein 2 (SREBP-2) is increased in Atp7b-/- nuclei. However, the SREBP-2 target genes are dysregulated suggesting that elevated copper alters SREBP-2 function rather than its processing or re-localization. Thus, in Atp7b-/- mice elevated copper affects specific cellular targets at the transcription and/or translation levels and has distinct effects on liver metabolic function, prior to appearance of histopathological changes. The identification of the network of specific copper-responsive targets facilitates further mechanistic analysis of human disorders of copper misbalance. Copper plays an essential role in human physiology. It serves as a cofactor of key metabolic enzymes and is required for embryonic development, neuronal myelination, radical detoxification, and numerous other physiological processes. Mutations in copper-binding proteins have been linked to such devastating disorders as amyotrophic lateral sclerosis, Alzheimer disease, prion disease, and Menkes disease. In Wilson disease (WD), 4The abbreviations used are: WD, Wilson disease; VLDL, very low density lipoprotein; LDL, low density lipoprotein; LDLR, low density lipoprotein receptor; WT, wild type; KO, knock-out; DTT, dithiothreitol; CHAPS, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid; RT, real time; HMG, hydroxymethylglutaryl; MS/MS, tandem mass spectrometry; CAPS, 3-(cyclohexylamino)propanesulfonic acid; GO, Gene Ontology; SREBP-2, sterol regulatory-binding protein 2; SOD1, superoxide dismutase 1. 4The abbreviations used are: WD, Wilson disease; VLDL, very low density lipoprotein; LDL, low density lipoprotein; LDLR, low density lipoprotein receptor; WT, wild type; KO, knock-out; DTT, dithiothreitol; CHAPS, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid; RT, real time; HMG, hydroxymethylglutaryl; MS/MS, tandem mass spectrometry; CAPS, 3-(cyclohexylamino)propanesulfonic acid; GO, Gene Ontology; SREBP-2, sterol regulatory-binding protein 2; SOD1, superoxide dismutase 1. the direct link between elevated hepatic copper and development of liver pathology has been firmly established. The disease is caused by mutations of the copper-transporting ATPase ATP7B (Wilson disease protein) (1Cox D. Roberts E. Feldman M. Friedman L. Brandt L.S. Wilson Disease, W. B. Saunders Co., Philadelphia. 2006: 1601-1612Google Scholar, 2Ferenci P. Metab. Brain Dis. 2004; 19: 229-239Crossref PubMed Scopus (107) Google Scholar, 3Gitlin J.D. Gastroenterology. 2003; 125: 1868-1877Abstract Full Text Full Text PDF PubMed Scopus (309) Google Scholar). ATP7B is expressed predominantly in the liver, where it transports copper from the cytosol into the lumen of the Golgi network for incorporation into ceruloplasmin, a copper-dependent ferroxidase. ATP7B is also required to export excess copper from the liver into the bile; this represents the major excretory route for copper in the body (4Loudianos G. Gitlin J.D. Semin. Liver Dis. 2000; 20: 353-364Crossref PubMed Scopus (141) Google Scholar). In WD patients, both functions are disrupted, and copper accumulates to levels that are 10-20-fold higher than the norm (5Brewer G.J. Am. J. Clin. Nutr. 1998; 67: S1087-S1090Crossref Scopus (36) Google Scholar). Gradual copper accumulation, most noticeable in the liver, induces marked changes in tissue structure and function. Liver injury is the most common manifestation of WD, although neurological and psychiatric symptoms are also frequently observed (2Ferenci P. Metab. Brain Dis. 2004; 19: 229-239Crossref PubMed Scopus (107) Google Scholar, 4Loudianos G. Gitlin J.D. Semin. Liver Dis. 2000; 20: 353-364Crossref PubMed Scopus (141) Google Scholar, 6Stremmel W. Meyerrose K.W. Niederau C. Hefter H. Kreuzpaintner G. Strohmeyer G. Ann. Intern. Med. 1991; 115: 720-726Crossref PubMed Scopus (261) Google Scholar). WD patients may show progressive hepatic cirrhosis, chronic active hepatitis, or rapidly developing liver failure (7Riordan S.M. Williams R. J. Hepatol. 2001; 34: 165-171Abstract Full Text Full Text PDF PubMed Scopus (128) Google Scholar). None of these clinical features is specific to WD, complicating its diagnosis. Remarkably, despite a long history (WD was described in 1912 (8Wilson S.A.K. Brain. 1912; 34: 295-507Crossref Scopus (766) Google Scholar)) and significant progress in characterization of its genetic basis (9Tanzi R.E. Petrukhin K. Chernov I. Pellequer J.L. Wasco W. Ross B. Romano D.M. Parano E. Pavone L. Brzustowicz L.M. Devoto M. Peppercorn J. Bush A.T. Sternlieb I. Pirastu M. Gusella J.F. Evgrafov O. Penchaszadeh G.K. Honig B. Edelman I.S. Soares M.B. Scheinberg I.H. Gilliam T.C. Nat. Genet. 1993; 5: 344-350Crossref PubMed Scopus (1177) Google Scholar, 10Bull P.C. Thomas G.R. Rommens J.M. Nat. Genet. 1993; 5: PubMed Scopus Google Scholar, Gitlin J.D. 1993; PubMed Scopus Google the molecular and metabolic changes that stages of copper may as of disease The effects of copper on lipid and have been in both patients and in animal of WD Semin. Liver Dis. PubMed Scopus Google Scholar, L.M. 2003; PubMed Scopus Google Scholar, 2001; PubMed Scopus Google it is which of these are the effects of copper and which are the of the disease. the changes is particularly such changes may as a but also or to observed metabolic and further and To understand molecular associated with the stages of copper we have Atp7b-/- mice, an animal model of We have that these copper to levels and have features WD D. J.L. R. S.M. Gilliam Am. J. Full Text Full Text PDF PubMed Scopus Google Scholar). We have also observed that in the Atp7b-/- mice, the hepatic copper is at its the pathology is D. J.L. R. S.M. Gilliam Am. J. Full Text Full Text PDF PubMed Scopus Google Scholar). this presymptomatic the changes in as well as associated metabolic in the liver are likely to specific to In this we changes in the hepatic and in to copper in Atp7b-/- We that the of copper is and distinct metabolic in the although is The most significant and are the of cell cycle machinery and the of cholesterol the is accompanied by marked decrease of cholesterol in the the for mechanistic analysis of WD and other copper-induced of the Atp7b-/- has been described J. K. Ross C. Scheinberg I.H. Gilliam T.C. Genet. 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It is in the in the of SREBP-2 is by the levels of cholesterol is SREBP-2 is to Golgi and The is from the to the and to the sterol stimulating cholesterol and levels of We have that elevated copper may SREBP-2 or of activated SREBP-2 into the cholesterol biosynthesis. However, analysis of in from and Atp7b-/- that SREBP-2 is and at higher levels in the of Atp7b-/- mice The SREBP-2 in Atp7b-/- and in Wilson SREBP-2 we the amount of mRNA for low density lipoprotein The transcription of the is by SREBP-2 and is to up-regulated in to increased SREBP-2 C. J. J.L. 1993; PubMed Scopus Google Scholar, J.D. I. R.E. J.L. H. J. Clin. 1998; PubMed Google Scholar). that despite levels of SREBP-2 in Atp7b-/- the amount of mRNA was in with that elevated copper SREBP-2 function in Atp7b-/- livers. To the of these to human disease, we the mRNA levels in liver from Wilson disease patients and The mRNA was in Wilson disease liver in with in Atp7b-/- which plays a role in cholesterol is target of SREBP-2 that was in Atp7b-/- mice of human mRNA by real that levels markedly in Wilson disease with In this we have the Atp7b-/- mice, an animal model for Wilson disease, and changes in the and associated with copper in the We show that prior to development of copper has a distinct and on liver and We that the of lipid and changes in the cell cycle machinery presymptomatic stages of WD, plays a of copper-induced mRNA changes with mRNA of liver to C. C. E. Nutr. Metab. PubMed Scopus Google Scholar, R. C. G. W. B. PubMed Scopus Google Scholar, P. J. L. 19: PubMed Scopus Google Scholar, L. J. E. 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