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 453 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Quantitative and qualitative changes in the inhibition of DNA adduct formation in the presence of increasing concentrations of norharman (NH) were investigated in vivo in mouse fibroblasts treated with dibenzo[a,e]fluoranthene (DBF), a potent carcinogen in mice. The nuclease P1 modification of the 32P-postlabeling technique was used to identify adducts. A dose-dependent reduction in DBF-DNA adduct formation was observed: an 80% reduction with 0.06 mM NH and 90% with 0.12 mM NH. At 0.12 mM NH, all of the spots coming from hydroxylated DBF vicinal dihydrodiol (DHD) epoxides were missing; the only clear spot was that of the major DBF adduct produced by the ultimate DBF metabolite, DBF-3,4-DHD-1,2 oxide. Spots representing other DBF-DHD epoxide adducts appeared only in trace amounts. These results can be interpreted as a dose-dependent competition or inhibition of some secondary metabolic step, most probably secondary epoxidation; however, a direct protective effect of NH during adduct formation cannot be excluded. NH is a strong inhibitor of DBF-DNA adduct formation in vivo.
Carcinogenesis 1992 Apr
PMID:32P-postlabeling analysis of inhibition by norharman of formation of dibenzo[a,e]fluoranthene--DNA adducts in mouse embryo fibroblasts. 157 24

Deviations in the pattern of soluble proteins from chemically induced primary rat hepatomas and from transformed, tumorigenic liver cell lines were determined by high resolution two-dimensional gel electrophoresis (2DE). As compared with the protein pattern of normal rat liver with approximately 1300 protein spots visible in silver-stained gels, quantitative and qualitative alterations were found in hepatomas including neoexpression of glutathione-S-transferase P, as described earlier. After correction for proliferation-related changes by comparison with gels of cells from regenerating rat liver, 30 protein variants remained, which were identically up- (n = 6) or down-regulated (n = 18) or were detected as new spots (n = 6) in primary hepatomas and transformed tumorigenic liver cell lines which are devoid of contaminating nonparenchymal cells. Seven of these variants showed a reduced expression in short-term cultured liver cells indicating dedifferentiation processes in the transformed state. Several hepatoma- and transformation-associated variants were found in clusters of similar mol. wt and/or pI, among them a complex of eight protein variants at approximately 33-35.5 kDa and a pI of approximately 6.6-7.4. Spots of this cluster show considerable changes between the investigated experimental groups and might be suited for being studied at the level of posttranslational modification during carcinogenesis.
Carcinogenesis 1992 Jul
PMID:Variant protein patterns in hepatomas and transformed liver cell lines as determined by high resolution two-dimensional gel electrophoresis (2DE). 163 84

Von Recklinghausen's disease, or neurofibromatosis type 1 (NF-1), is an autosomal dominant syndrome with a highly variable tumorous (neurofibromas, gliomas, Wilms' tumors, leukemia, pheochromocytomas) and non-tumorous (cafe-au-lait skin spots, iris and ciliar hamartomas, osseous lesions) manifestations. NF-1 gene is mapped to chromosome 17. Central or bilateral acoustic neurofibromatosis (NF-2) has a gene mapped to chromosome 22. Hereditary and sporadic NF-1 are recognized. The most typical manifestation of NF-1-skin neurofibroma--has has a characteristic plexiform structure. Spectrum of tumors (schwannomas, gliomas, Wilms' tumors) produced by transplacental treatment with strong environmental mutagens-carcinogens-ethylnitroso- and methylnitrosourea (ENU and MNU, respectively) resembles on the whole that observed in human sporadic NF-1. Location of neurofibromas depends on the species: skin and subcutaneous tissue in humans, cattle and hamsters, trigeminal nerve, spinal roots in rats. Rat schwannomas differ from human neurofibromas by malignant structure, frequently with cystic component, but if induced by ENU treatment at day 15 of the pregnancy they resemble human plexiform neurofibromas with intraneural and extraneural growth of tumor cells. There were attempts to reproduce a transgenerational transmission of ENU carcinogenic effect, i.e. hereditary form of NF-1. In the experiments of this type the offsprings of rats prenatally treated with ENU remained untreated. The incidence of PNS, CNS and Wilms' tumors in these untreated offsprings in some experiments was significantly higher than in controls thus confirming the possibility, in principle, of hereditary NF-1 modelling. Only 10% of tumors developing in such untreated descendants of ENU treated parents contained a specific mutation of neu oncogene compared to 90-100% in tumors arising following direct treatment with ENU. The mechanisms of the transgenerational carcinogenesis are discussed. Lesions imitating NF-1 and in part NF-2 in transgenic mice with an HTLV-1-tax gene as well as in p-53 knockout mice are mentioned.
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PMID:[Von Recklinghausen's disease: experimental models and comparative aspects]. 900 21

Polycyclic aromatic hydrocarbon (PAH) DNA adducts have been associated with carcinogenesis, which is accompanied by multiple alterations in gene expression. We used two-dimensional electrophoresis to distinguish protein expression changes induced in MCF-7 cells by individual PAH (B[a]P and DB[a,l]P) and PAH mixtures (coal tar extract [SRM 1597] and diesel exhaust extract [SRM 1975]). Spots of interest were identified by MALDI-TOF-TOF. Our results have shown alterations in the expression of heat-shock proteins, cytoskeletal proteins, DNA associated proteins, and glycolytic and mitochondrial proteins. The proteins that were universally altered in expression were actin cytoplasmic 1, tubulin alpha and myosin light chain alkali, cyclophilin B, and heterogeneous ribonucleoprotein B1 (a protein involved in access to telomerase and mRNA maturation). Additional proteins with altered expression include histone H2A.1, heat-shock protein 70-2, galectin-3, nucleoside diphosphate kinase, ATP synthase, and electron transfer flavoprotein. While sharing similarities, each PAH treatment exhibited a unique proteomic fingerprint.
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PMID:Proteomic analysis of MCF-7 cells treated with benzo[a]pyrene, dibenzo[a,l]pyrene, coal tar extract, and diesel exhaust extract. 1849 19