Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In vitro studies of the effect of aflatoxin B1-dichloride (AFB1-Cl2) on the template function for RNA synthesis of several single- and double-stranded synthetic DNAs containing cytosine and/or hypoxanthine bases are reported. The results indicate: (i) AFB1-Cl2 strongly inhibits the template function of the single-stranded homopolymer polydC and has no effect on polydI, (ii) the inhibition is stronger when cytosine is in the double-stranded alternating copolymer poly[d(I-C)], and (iii) polydI directed RNA synthesis can be inhibited if it is in the double-stranded homopolymer polydI.polydC, although the template function of the polydC strand is still inhibited to a greater extent. The evidence that the selective inhibition of the DNA template function is a direct reflection of the binding specificities of AFB1-Cl2 is provided by the binding studies of [3H]AFB1-Cl2 to these DNAs. The binding of AFB1-Cl2 to polydC is substantiated by the dose-response template inhibition and by the dose-response template binding studies. Additionally, these results show that AFB1 per se has neither inhibitory nor binding activity. Auto radiography of [alpha-32P]GTP labeled RNAs suggests that the mechanism of inhibition of polydC template function by AFB1-Cl2 is mainly due to the inhibition of the elongation of RNA synthesis. Spectrum measurement of the products of enzyme digestion of the AFB1-Cl2 modified polydC reveals that the deoxycytidine fraction gives a typical cytosine absorption peak at 275 nm followed by a broad peak between 300 and 400 nm with a maximum at 390 nm. High performance liquid chromatography confirms the existence of a cytosine-AFB1 adduct which absorbs strongly in the regions between 250 and 400 nm with peaks identifiable at 260, 350 and 390 nm. These results strongly suggest that AFB1 in the activated form of AFB1-Cl2 is able to covalently bind to cytosine in DNA.
Carcinogenesis 1991 Jun
PMID:Evidence for the covalent binding of aflatoxin B1-dichloride to cytosine in DNA. 171 May 45

Three rat liver foci bioassays have been compared with respect to their sensitivity by the histochemical demonstration of preneoplastic foci, and by the biochemical determination of alterations in enzyme activities of serum indicating hepatotoxicity. We studied the initiation/promotion schedules according to Oesterle and Deml (A), and according to Pereira (B, Broad Spectrum Protocol), and the initiation/selection protocol according to Tatematsu et al. (C), with diethylnitrosamine (DEN), given as a single initiating dose of 10 and 30 mg/kg body wt respectively. With all schedules Sprague-Dawley rats, either females, 3 weeks old (A), or males, 6 weeks old (B, C) were used. For promotion polychlorinated biphenyls (A) or phenobarbital (B) were administered. Selection was performed with 2-acetylaminofluorene (C). The rats in schemes (B) and (C) underwent partial hepatectomy one day prior to initiation. The number and total area of foci deficient in adenosine-5'-triphosphatase (ATPase) and positive in gamma-glutamyltranspeptidase (GGTase) was evaluated. In the complete schedule with 30 mg of DEN in system (A) foci incidence exceeded that of the other systems by about 7-fold (ATPase) and 2-fold (GGTase) respectively. The lower dose of DEN and all control experiments resulted in a respective lower foci yield. With scheme (C), but not with schemes (A) and (B), e.g. serum fructose-1.6-bisphosphatase and alkaline phosphatase were increased, suggesting liver cell damage. Thus tested with DEN, scheme (A) is most sensitive and causes a low impairment of animals' welfare.
Carcinogenesis 1989 Oct
PMID:Comparison of three rat liver foci bioassays--incidence of preneoplastic foci initiated by diethylnitrosamine. 257 25

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

Types and frequencies of in vivo mutation in the hypoxanthine-guanine phosphoribosyl-transferase (HPRT) gene was studied in 142 T cell mutants from 78 healthy nonsmoking and smoking adults with a mean of 65 years. The HPRT mutant frequency in the nonsmokers was 18.7 +/- 12.0 x 10(-6), and in the smokers 26.6 +/- 18.5 x 10(-6) (mean +/- S.D., P < 0.01). Among 107 single base pair substitutions (SBS) in the coding region of the HPRT gene, one new mutable site, one novel nonsense mutation and three not previously reported SBS were identified. Transitions accounted for 59% of the SBS and transversions for 41%. GC > AT transitions were the predominant type of mutation, with 50% of all SBS. The mutations showed a nonrandom distribution along the coding sequence, with three significant hotspots at positions 143, 197 and 617 (13, 14 and 7 mutations, respectively). There was no difference between smokers and nonsmokers with regard to the distribution of mutations at these hotspot positions. However, 85% of the mutations at GC base pairs and 88% of the mutations at AT base pairs in smokers occurred at sites with guanine or thymine, respectively, in the nontranscribed DNA strand. Moreover, smokers had a higher frequency of transversions and lower frequency of transitions than nonsmokers did. Particularly, GC > TA transversions were increased in smokers (11%) compared to nonsmokers (2%), which suggests that tobacco-smoke induced adducts at guanine bases in the nontranscribed DNA strand contributes to the increase of HPRT mutation in smokers. Overall, these results were very similar to the mutational spectra in two younger study populations reported previously [K.J. Burkhart-Schultz, C.L. Thompson, I.M. Jones, Spectrum of somatic mutation at the hypoxanthine phosphoribosyltransferase (HPRT) gene of healthy people, Carcinogenesis 17 (1996) 1871-1883; A. Podlutsky, A.-M. Osterholm, S.-M. Hou, A. Hofmaier, B. Lambert, Spectrum of point mutations in the coding region of the hypoxanthine-guanine phosphoribosyltransferase, Carcinogenesis 19 (1998) 557-566]. With the possible exception of an increase of mutations at hotspot position 143, and a decrease of 5-methylcytosine deamination mediated transitions at CpG-sites in the older individuals, there were no differences between the mutational spectra of old and young adults. In conclusion, both smoking and ageing seem to have minor influences on the spectrum of HPRT mutation in T cells.
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PMID:Influence of smoking and donor age on the spectrum of in vivo mutation at the HPRT-locus in T lymphocytes of healthy adults. 1063 98

C.I. Direct Blue 15 is one of five chemicals being evaluated in 2-year carcinogenicity and toxicity studies as part of the NTP's Benzidine Dye Initiative. This Initiative was designed to evaluate representative benzidine congeners, benzidine congener-derived dyes, and benzidine-derived dyes. The dye, industrial grade C.I. Direct Blue 15, was chosen for study as a product to which workers are potentially exposed. Because of the high salt content, the dye was desalted prior to use. The purity was determined to be approximately 50%, with high-performance liquid chromatography indicating one major peak and approximately 35 impurities. Toxicology and carcinogenesis studies were conducted by administering the dye, C.I. Direct Blue 15, in drinking water to groups of F344/N rats of each sex for 14 days, 13 weeks, or 22 months. Planned as 24-month studies, the 22-month studies were terminated early because of rapidly declining animal survival, which was due primarily to neoplasia. These studies were performed only in rats because studies of benzidine congeners were being performed in mice at the National Center for Toxicological Research (NCTR). Genetic toxicology studies were conducted in Salmonella typhimurium and Chinese hamster ovary cells. 14-Day Studies: Rats were given C.I. Direct Blue 15 in drinking water at doses of 1,250, 2,500, 5,000, 10,000, or 30,000 ppm. All control and treated rats survived. Body weight gain in high-dose females was less than that in controls. Water consumption declined as the dose increased. Male and female rats receiving 30,000 ppm had slight degeneration and necrosis of individual hepatocytes in the liver, and females also had mild to moderate renal tubule degeneration and thymic lymphoid depletion. 13-Week Studies: C.I. Direct Blue 15 was administered in drinking water at doses of 0, 1,250, 2,500, 5,000, 10,000, or 30,000 ppm to male rats, and at doses of 0, 630, 1,250, 2,500, 5,000, or 10,000 ppm to female rats. Seven of 10 male rats receiving 30,000 ppm died; all rats in the other groups survived until the end of the studies. Mean final body weights of males receiving 10,000 or 30,000 ppm were 92% and 69% of those of controls, and mean final body weights of females receiving 5,000 or 10,000 ppm were 97% and 94% of those of controls. Tissues from treated animals were stained blue. Compound-related lesions were seen in the kidney and liver of male rats given 30,000 ppm and in the kidney of males and females given 10,000 ppm. The renal lesions included necrosis, degeneration, pigmentation and regeneration of the tubule epithelium, and tubule mineralization. Liver lesions included centrilobular hepatocellular degeneration, fatty metamorphosis, and individual cell necrosis with slight periportal hepatocellular hypertrophy. Lymphoid depletion in the thymus was also seen in the high-dose males. Based on the results of the 14-day and 13-week studies, the high dose chosen for the 22-month studies was 2,500 ppm. 22-Month Studies: At study initiation, 70 rats of each sex were given 0 or 2,500 ppm C.I. Direct Blue 15, 45 rats of each sex were given 630 ppm, and 75 rats of each sex were given 1,250 ppm. Interim evaluations were made at 9 and 15 months. The average amounts of compound consumed per day by the six dose groups after week 52 of the studies were estimated to be 45, 90, and 215 mg/kg for male rats and 50, 100, and 200 mg/kg for female rats. Survival and Body Weights: The studies were terminated at 22 months due to extensive mortality associated with chemical-related neoplasia. Survival of control, 630, 1,250, and 2,500 ppm males at 22 months was 37/50, 8/35, 11/65, and 2/50; survival of females was 40/50, 13/35, 22/65, and 4/50. At 22 months, the mean final body weights of the 630, 1,250, and 2,500 ppm groups were 95%, 91%, and 81% of those of the control for male rats and 91% of those of the control for all female dose groups. Histopathologic Effects in the 22-Month Studies: At the 9-month interim evaluations, one adenoma of the Zymbal's gland was seen in a high-dose male rat, and three carcinmbal's gland was seen in a high-dose male rat, and three carcinomas of the clitoral gland were seen in the high-dose females. At the 15-month interim evaluations, Zymbal's gland neoplasms were seen in low- and high-dose males and all treated female dose groups. Mid- and high-dose males and females also had preputial or clitoral gland neoplasms, and a few neoplasms were present in the skin, small and large intestine, liver, and oral cavity of treated animals at 15 months. At the end of the study, neoplasms related to chemical administration were found in the Zymbal's gland, skin, oral cavity, and the preputial or clitoral gland in both male and female rats. Neoplasms related to chemical administration were also seen at other sites including the small and large intestine, liver, uterus, and brain. The incidence of mononuclear cell leukemia was also increased in treated rats. Genetic Toxicology: C.I. Direct Blue 15 was not mutagenic in Salmonella typhimurium strains TA100, TA1535, TA1537, and TA98 when tested in a standard preincubation protocol with or without exogenous metabolic activation; however, when a specialized reductive metabolism protocol was used, C.I. Direct Blue demonstrated mutagenic activity in Salmonella strain TA1538. C.I. Direct Blue 15 did not induce sister chromatid exchanges or chromosomal aberrations in Chinese hamster ovary cells with or without S9 activation; reductive metabolism was not used in these cytogenetic tests. Conclusions: Under the conditions of these 22-month drinking water studies, there was clear evidence of carcinogenic activity of C.I. Direct Blue 15 (desalted industrial grade) in male F344/N rats, as indicated by benign and malignant neoplasms of the skin, Zymbal's gland, preputial gland, liver, oral cavity, and small and large intestine. Increased incidences of mononuclear cell leukemia and neoplasms of the brain may have been related to chemical administration. There was clear evidence of carcinogenic activity of C.I. Direct Blue 15 in female F344/N rats, as indicated by benign and malignant neoplasms of the skin, Zymbal's gland, clitoral gland, liver, oral cavity, small and large intestine, and uterus, and by mononuclear cell leukemia. Synonyms: Airedale Blue D, Aizen Direct Sky Blue 5BH, Amanil Sky Blue, Atlantic Sky Blue A, Atul Direct Sky Blue, Azine Sky Blue 5B, Belamine Sky Blue A, Benzanil Sky Blue, Benzo Sky Blue S, Benzo Sky Blue A-CF, Cartasol Blue 2GF, Chloramine Sky Blue A, Chloramine Sky Blue 4B, Chrome Leather Pure Blue, C.I. 24400, Cresotine Pure Blue, Diacotton Sky Blue 5B, Diamine Blue 6B, Diamine Sky Blue, Diaphtamine Pure Blue, Diazol Pure Blue 4B, 3,3'-[(3,3'-dimethoxy[1,1'-biphenyl]-4,4'-diyl)bis(azo)]bis[5-amino-4-hydroxy-2,-naphthalenedisulfonic acid] tetrasodium salt, Diphenyl Brilliant Blue, Diphenyl Sky Blue 6B, Direct Blue 10G, Direct Blue HH, Direct Pure Blue, Direct Pure Blue M, Direct Sky Blue (6CI), Direct Sky Blue A, Direct Sky Blue 5B, Enianil Pure Blue AN, Fenamin Sky Blue, Hispamin Sky Blue 3B, Kayafect Blue Y, Kayaku Direct Sky Blue 5B, Mitsui Direct Sky Blue 5B, Naphtamine Blue 10G, Niagara Blue 4B, Niagara Sky Blue, Nippon Direct Sky Blue, Nitto Direct Sky Blue 5B, Paper Blue S, Phenamine Sky Blue A, Pontamine Sky Blue 5BX, Shikiso Direct Sky Blue 5B, Sky Blue 4B, Sky Blue 5B, Tertrodirect Blue F, Vondacel Blue HH
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PMID:NTP Toxicology and Carcinogenesis Studies of C.I. Direct Blue 15 (CAS No. 2429-74-5) in F344 Rats (Drinking Water Studies). 1263 62

Early identification of premalignant and malignant gastric mucosa is crucial to decrease the incidence and mortality of stomach cancer. Spectrum- and time-resolved multiphoton microscopy are capable of providing not only structural but also biochemical information at the subcellular level. Based on this multidimensional imaging technique, we performed a systematic investigation on fresh human tissue specimens at the typical stages of gastric carcinogenesis, including normal, chronic gastritis with erosion, chronic gastritis with intestinal metaplasia, and intestinal-type adenocarcinoma. The results demonstrate that this technique is available to characterize the three-dimensional subcellular morphological and biochemical properties of gastric mucosa and further provide quantitative indicators of different gastric disorders, by using endogenous contrast. With advances in multiphoton endoscopy, it has the potential to allow noninvasive, label-free, real-time histological and functional diagnosis of premalignant and malignant lesions of stomach in the future.
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PMID:Spectrum- and time-resolved endogenous multiphoton signals reveal quantitative differentiation of premalignant and malignant gastric mucosa. 2955 86