TY  - JOUR
A1  - Ohgaki, H.
A1  - Ludeke, B. I.
A1  - Meier, I.
A1  - Kleihues, P.
A1  - Lutz, Werner K.
A1  - Schlatter, C.
T1  - DNA methylation in the digestive tract of F344 rats during chronic exposure to N-methyl-N-nitrosourea
N2  - The formation of \(O^6\)-methyldeoxyguanosine (\(O^6\)-MedGuo) was determined by an immuno-slot-blot assay in DNA of various tissues of F344 rats exposed to N-methyl-N-nitrosourea (MNU) in the drinking waterat 400 ppm for 2 weeks. Although the pyloric region of the glandular stomach is a target organ under these experimental conditions, the extent of DNA methylation was highest in the forestomach (185 \(\mu\)mol \(O^6\)-MedGuojmol guanine). Fundus (91 J.!moljmol guanine) and pylorus (105 J.!moljmol guanine) of the glandular stomach, oesophagus (124 \(\mu\)mol/mol guanine) and duodenum (109 )lmoljmol guanine) showed lower Ievels of \(O^6\) - MedGuo but differed little between each other. Thus, no correlation was observed between target organ specificity and the extent of DNA methylation. This is in contrast to the gastric carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), which preferentially alkylates DNA of the pylorus, the main site of induction of gastric carcinomas by this chemical. In contrast to MNU, the nonenzymic decomposition of MNNG is accelerated by thiol compounds (reduced glutathione, L-cysteine), which are present at much higher concentrations in the glandular stomach than in the forestomach and oesophagus. During chronic exposure to MNNG (80 ppm), mucosal cells immunoreactive to 0 6-MedGuo are limited to the luminal surface [Kobori et al. (1988) Carcinogenesis 9:2271-2274]. Although MNU (400 ppm) produced similar Ievels of \(O^6\)-MedGuo in the pylorus, no cells containing methylpurines were detectable by immunohistochemistry, suggesting a more uniform methylation of mucosal cells by MNU than by MNNG. After a single oral dose of MNU (90 mg/kg) cells containing methylpurines were unequivocally identified using antibodies to \(O^6\)-MedGuo and the imidazole-ring-opened product of 7-methyldeoxyguanosine. In the gastric fundus, their distribution was similar to those methylated by exposure to MNNG, whereas the pyloric region contained immunoreactive cells also in the deeper mucosallayers. After a 2-week MNU treatment, the rate of cell proliferation, as determined by bromodeoxyuridine immunoreactivity, was only slightly enhanced in the oesophagus andin the fundus, but markedly in the forestomach and the pyloric region of the glandular stomach. lt is concluded that the overall extent of DNA methylation, the distribution of alkylated cells within the mucosa and the proliferative response all contribute to the organ-specific carcinogenicity of MNU.
KW  - Toxikologie
KW  - Gastric carcinogenesis
KW  - N-methyl-N-nitrosourea
KW  - DNA methylation
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60759
ER  - 
TY  - JOUR
A1  - Meier, I.
A1  - Shephard, S. E.
A1  - Lutz, Werner K.
T1  - Nitrosation of aspartic acid, aspartame, and glycine ethylester. Alkylation of 4-(p-nitrobenzyl)pyridine (NBP) in vitro and binding to DNA in the rat
N2  - In a colorimetric assay using 4-( p-nitrobenzyl)pyridine (NBP) as a nucleophilic scavenger of alkylating agents, the nitrosation and alkylation reactions were investigated for a number of amino acids and derivatives. The alkylating activity increased with the square of the nitrite concentration. The nitrosation rate constants for aspartic acid, aspartame, and glycine ethylester ( = precursors C) were 0.08, 1.4 and ~ 0.2, respectively, expressed in terms of the pH-dependent \(k_2\) rate constant of the equation dNOCjdt = \(k_2\) • (C]· [nitrite]\(^2\) • The rates correlated inversely with the basicity of the amino group. The stability of the alkylating activity was astonishingly high, both in acid and at neutral pH. Half-lives of 500, 200, and 30 min were determined for aspartic acid (pH 3.5), aspartame (pH 2.5), and glycine ethylester (pH 2.5). Values of 60, 15, and 2 min; respectively, were found at pH 7. It is concluded that rearrangement of the primary N-nitroso product to the ultimate alkylating agent could be rate-limiting. The potential of nitrosated a-amino acids to bind to DN A in vivo was investigated by oral gavage of radiolabelled glycine ethylester to rats, followed irnmediately by sodium nitrite. DNA was isolated from stomach and liver and analysed for radioactivity and modified nucleotides. No indication of DNA adduct formation was obtained. Based on an estimation of the dose fraction converted from glycine ethylester to the nitroso product under the given experimental conditions, the maximum possible DNA-binding potency of nitroso glycine ethylester is about one order of magnitude below the methylating potency of N-nitrosomethylurea in rat stomach. The apparent discrepancy to the in vitro data could be due to efficient detoxification processes in mammalian cells.
KW  - Toxikologie
KW  - Nitrosation
KW  - Alkylation
KW  - Amino acids
KW  - DNA binding
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60804
ER  - 
TY  - JOUR
A1  - Galluzzi, L.
A1  - Bravo-San Pedro, J. M.
A1  - Vitale, I.
A1  - Aaronson, S. A.
A1  - Abrams, J. M.
A1  - Adam, D.
A1  - Alnemri, E. S.
A1  - Altucci, L.
A1  - Andrews, D.
A1  - Annicchiarico-Petruzelli, M.
A1  - Baehrecke, E. H.
A1  - Bazan, N. G.
A1  - Bertrand, M. J.
A1  - Bianchi, K.
A1  - Blagosklonny, M. V.
A1  - Blomgren, K.
A1  - Borner, C.
A1  - Bredesen, D. E.
A1  - Brenner, C.
A1  - Campanella, M.
A1  - Candi, E.
A1  - Cecconi, F.
A1  - Chan, F. K.
A1  - Chandel, N. S.
A1  - Cheng, E. H.
A1  - Chipuk, J. E.
A1  - Cidlowski, J. A.
A1  - Ciechanover, A.
A1  - Dawson, T. M.
A1  - Dawson, V. L.
A1  - De Laurenzi, V.
A1  - De Maria, R.
A1  - Debatin, K. M.
A1  - Di Daniele, N.
A1  - Dixit, V. M.
A1  - Dynlacht, B. D.
A1  - El-Deiry, W. S.
A1  - Fimia, G. M.
A1  - Flavell, R. A.
A1  - Fulda, S.
A1  - Garrido, C.
A1  - Gougeon, M. L.
A1  - Green, D. R.
A1  - Gronemeyer, H.
A1  - Hajnoczky, G.
A1  - Hardwick, J. M.
A1  - Hengartner, M. O.
A1  - Ichijo, H.
A1  - Joseph, B.
A1  - Jost, P. J.
A1  - Kaufmann, T.
A1  - Kepp, O.
A1  - Klionsky, D. J.
A1  - Knight, R. A.
A1  - Kumar, S.
A1  - Lemasters, J. J.
A1  - Levine, B.
A1  - Linkermann, A.
A1  - Lipton, S. A.
A1  - Lockshin, R. A.
A1  - López-Otín, C.
A1  - Lugli, E.
A1  - Madeo, F.
A1  - Malorni, W.
A1  - Marine, J. C.
A1  - Martin, S. J.
A1  - Martinou, J. C.
A1  - Medema, J. P.
A1  - Meier, P.
A1  - Melino, S.
A1  - Mizushima, N.
A1  - Moll, U.
A1  - Muñoz-Pinedo, C.
A1  - Nuñez, G.
A1  - Oberst, A.
A1  - Panaretakis, T.
A1  - Penninger, J. M.
A1  - Peter, M. E.
A1  - Piacentini, M.
A1  - Pinton, P.
A1  - Prehn, J. H.
A1  - Puthalakath, H.
A1  - Rabinovich, G. A.
A1  - Ravichandran, K. S.
A1  - Rizzuto, R.
A1  - Rodrigues, C. M.
A1  - Rubinsztein, D. C.
A1  - Rudel, T.
A1  - Shi, Y.
A1  - Simon, H. U.
A1  - Stockwell, B. R.
A1  - Szabadkai, G.
A1  - Tait, S. W.
A1  - Tang, H. L.
A1  - Tavernarakis, N.
A1  - Tsujimoto, Y.
A1  - Vanden Berghe, T.
A1  - Vandenabeele, P.
A1  - Villunger, A.
A1  - Wagner, E. F.
A1  - Walczak, H.
A1  - White, E.
A1  - Wood, W. G.
A1  - Yuan, J.
A1  - Zakeri, Z.
A1  - Zhivotovsky, B.
A1  - Melino, G.
A1  - Kroemer, G.
T1  - Essential versus accessory aspects of cell death: recommendations of the NCCD 2015
JF  - Cell Death and Differentiation
N2  - Cells exposed to extreme physicochemical or mechanical stimuli die in an uncontrollable manner, as a result of their immediate structural breakdown. Such an unavoidable variant of cellular demise is generally referred to as 'accidental cell death' (ACD). In most settings, however, cell death is initiated by a genetically encoded apparatus, correlating with the fact that its course can be altered by pharmacologic or genetic interventions. 'Regulated cell death' (RCD) can occur as part of physiologic programs or can be activated once adaptive responses to perturbations of the extracellular or intracellular microenvironment fail. The biochemical phenomena that accompany RCD may be harnessed to classify it into a few subtypes, which often (but not always) exhibit stereotyped morphologic features. Nonetheless, efficiently inhibiting the processes that are commonly thought to cause RCD, such as the activation of executioner caspases in the course of apoptosis, does not exert true cytoprotective effects in the mammalian system, but simply alters the kinetics of cellular demise as it shifts its morphologic and biochemical correlates. Conversely, bona fide cytoprotection can be achieved by inhibiting the transduction of lethal signals in the early phases of the process, when adaptive responses are still operational. Thus, the mechanisms that truly execute RCD may be less understood, less inhibitable and perhaps more homogeneous than previously thought. Here, the Nomenclature Committee on Cell Death formulates a set of recommendations to help scientists and researchers to discriminate between essential and accessory aspects of cell death.
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121207
VL  - 22
ER  - 
TY  - CHAP
A1  - Shephard, S. E.
A1  - Meier, I.
A1  - Lutz, Werner K.
T1  - Alkylating potency of nitrosated amino acids and peptides
N2  - Tbe alkylating potency of unstable N-nitrosamino acids and N-nitrosopeptides was investigated in vitro using 4-(para-nitrobenzyl)pyridine (NBP) as nucleophile. Of the amino acids, Met and those with an aromatic side chain were the most potent. The relative overall alkylating potency was 23:10:5:4:2:1: for Trp, Met, His, 1)rr, Phe and Gly, respectively. The homo-dipeptides were much more potent than the amino acids, with relative potencies of 400:110:100:8:3:1, for Trp-Trp, l)T-'I)T, Met-Met, Asp-Asp, Phe-Phe and Gly, respectively. In the one-phase reaction system (in which NBP is already present durlog the nitrosation reaction at acidic pH), all amino acids tested showed a second-order reaction for nitrite. In the two-phase system (in which NBP is added only after bringing the nitrosation reaction mixture to neutrality), all amino acids tested except one again showed a second-order reaction for nitrite (Phe, His, Asp and the dipeptide artiticial sweetener aspartame); only Met under these conditions bad a reaction order of one for nitrite. This could mean that nitrosation of the side chain of Metproduces a second N-nitroso product which is relatively stable in acid but reacts with NBP under neutral conditions. In the human stomach, this side-chain nitrosation might become more important than the reactions at the primary amino group, firstly because of the greater stability of the product(s) in acid and secondly because of the tirst-order reaction rate for nitrite. A decrease in nitrite concentration from the millimolar concentrations ofthe in-vitro assay to the micromolar concentrations in the stomach reduces the reaction rate by a factor of 1000 for the side-chain nitrosation, whereas a million-fold reduction will be observed for nitrosation of the amino group.
KW  - Aminosäuren
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-86320
ER  - 
TY  - JOUR
A1  - Livingstone, E.
A1  - Zaremba, A.
A1  - Horn, S.
A1  - Ugurel, S.
A1  - Casalini, B.
A1  - Schlaak, M.
A1  - Hassel, J.C.
A1  - Herbst, R.
A1  - Utikal, J.S.
A1  - Weide, B.
A1  - Gutzmer, R.
A1  - Meier, F.
A1  - Koelsche, C.
A1  - Hadaschik, E.
A1  - Sucker, A.
A1  - Reis, H.
A1  - Merkelbach‐Bruse, S.
A1  - Siewert, M.
A1  - Sahm, F.
A1  - von Deimling, A.
A1  - Cosgarea, I.
A1  - Zimmer, L.
A1  - Schadendorf, D.
A1  - Schilling, B.
A1  - Griewank, K.G.
T1  - GNAQ and GNA11 mutant nonuveal melanoma: a subtype distinct from both cutaneous and uveal melanoma
JF  - British Journal of Dermatology
N2  - Background
GNAQ and GNA11 mutant nonuveal melanoma represent a poorly characterized rare subgroup of melanoma with a gene mutation profile similar to uveal melanoma.

Objectives
To characterize these tumours in terms of clinical behaviour and genetic characteristics.

Methods
Patients with nonuveal GNAQ/11 mutated melanoma were identified from the prospective multicentre tumour tissue registry ADOREG, Tissue Registry in Melanoma (TRIM) and additional cooperating skin cancer centres. Extensive data on patient, tumour and treatment characteristics were collected retrospectively. Targeted sequencing was used to determine tumour mutational burden. Immunohistochemistry staining was performed for programmed death‐ligand 1 and BRCA1‐associated protein (BAP)1. Existing whole‐exome cutaneous and uveal melanoma data were analysed for mutation type and burden.

Results
We identified 18 patients with metastatic GNAQ/11 mutant nonuveal melanoma. Tumours had a lower tumour mutational burden and fewer ultraviolet signature mutations than cutaneous melanomas. In addition to GNAQ and GNA11 mutations (nine each), six splicing factor 3b subunit 1 (SF3B1), three eukaryotic translation initiation factor 1A X‐linked (EIF1AX) and four BAP1 mutations were detected. In contrast to uveal melanoma, GNAQ/11 mutant nonuveal melanomas frequently metastasized lymphatically and concurrent EIF1AX, SF3B1 and BAP1 mutations showed no apparent association with patient prognosis. Objective response to immunotherapy was poor with only one partial response observed in 10 treated patients (10%).

Conclusions
Our findings suggest that GNAQ/11 mutant nonuveal melanomas are a subtype of melanoma that is both clinically and genetically distinct from cutaneous and uveal melanoma. As they respond poorly to available treatment regimens, novel effective therapeutic approaches for affected patients are urgently needed.

What is already known about this topic?
The rare occurrence of GNAQ/11 mutations in nonuveal melanoma has been documented.
GNAQ/11 mutant nonuveal melanomas also harbour genetic alterations in EIF1AX, SF3B1 and BAP1 that are of prognostic relevance in uveal melanoma.

What does this study add?
GNAQ/11 mutant nonuveal melanomas show metastatic spread reminiscent of cutaneous melanoma, but not uveal melanoma.
GNAQ/11 mutant nonuveal melanomas have a low tumour mutational burden that is higher than uveal melanoma, but lower than cutaneous melanoma.

What is the translational message?
Primary GNAQ/11 mutant nonuveal melanomas are a subtype of melanoma that is clinically and genetically distinct from both cutaneous and uveal melanoma.
As metastatic GNAQ/11 mutant nonuveal melanomas respond poorly to available systemic therapies, including immune checkpoint inhibition, novel therapeutic approaches for these tumours are urgently needed.
KW  - melanoma
KW  - GNAQ
KW  - GNA11
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-215434
VL  - 183
IS  - 5
SP  - 928
EP  - 939
ER  -