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

Because of the utility of the N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) rat model in the study of bladder cancer, the effect of dose on FANFT-induced bladder carcinogenesis was evaluated. Weaning male F344 rats were given FANFT in the diet at doses of 0.1, 0.05, 0.01, 0.005, 0.001, and 0.0005% for 30 weeks and then a control diet for 22 weeks. A control group received only the control diet throughout the experiment. Papillary tumors were present at the higher doses, hyperplasia of various degrees of severly was present at the intermediate doses, and minimal hyperplasia was observed in 4 of 16 rats at the 0.005% dose; no mucosal abnormalities were observed at the two lower doses or in the control group. Bladder epithelium from selected animals was also examined by scanning electron microscopy (SEM) after 10 weeks and again at the end of the experiment. Hyperplastic mucosa with pleomorphic microvilli similar to that previously demonstrated for 0.2% FANFT was observed at 10 weeks in rats fed 0.1% FANFT. Hyperplastic mucosa with pleomorphic microvilli was also observed at 52 weeks in rats fed 0.1% and 0.05% FANFT. Hyperplastic mucosa without pleomorphic microvilli was observed in rats fed 0.01 and 0.005% FANFT. The bladder appeared normal by light microscopy and SEM at the two lower doses and in the control group at both the 10- and 52-week intervals. A dose relationship was thus demonstrated for FANFT-induced bladder carcinogenesis in male F344 rats, and more severe surface changes were observed by SEM as the dose increased.
 ...
PMID:Effect of dose on urinary bladder carcinogenesis induced in F344 rats by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide. 28 73

Bladder tumors were induced in rats by the oral administration of 0.025% N-butyl-N-(hydroxybutyl) nitrosamine (BBN). In order to study the suppressive effects of rat interferon-alpha (IFN-alpha) on induction of carcinogenesis in vivo, rats were treated with IFN-alpha i.m. twice a week. The treatment began at 5th week of BBN administration. The bladder mucosa was observed macroscopically and microscopically, and NK activity was examined. The results were as follows. 1) There was no significant difference in the bladder to body weight ratio between the BBN + IFN-alpha and BBN groups in during stage A (10th-14th week when changes in the mucous membrane such as hypertrophy in the bladder wall or vascular formation are observed). This ratio in the BBN + IFN-alpha group was less than that in the BBN group in during stages B and C (15th-19th week and 20th-30th week respectively when tumors are visually recognizable). 2) The rate of carcinogenesis in the BBN + IFN-alpha group was less than that in the BBN group in stages A and C. 3) The pathological grade and stage of the bladder cancer in the BBN + IFN-alpha group were lower than those in the BBN group in stages B and C. 4) There was no significant difference in NK activity between the two groups in stage A, but NK activity of the BBN + IFN-alpha group was higher than that of the BBN group in stage B. 5) These findings substantiated the hypothesis that IFN-alpha can suppress tumor-growth in BBN induced bladder carcinoma.
 ...
PMID:[Inhibitory effects of IFN on N-butyl-N-(hydroxybutyl) nitrosamine induced rats bladder tumors]. 156 22

Several F1 mouse hybrids were used in a chronic bioassay to determine whether such an experimental design would provide greater statistical power than using only the B6C3F1 hybrid. For this purpose, the dose response of formation of hepatocellular and bladder tumors after 30 mo of feeding 2-acetylaminofluorene (2-AAF) in the diet was assessed in 4 F1 mouse hybrids, including the B6C3F1 hybrid. No strain background-related differences in frequency of bladder neoplasms between any F1 hybrids were detected. Bladder tumors occurred only at the highest 2-AAF dose in female mice. In males the lowest dose was already sufficient to induce bladder neoplasms with incidences of 25-48% adjusted for different nontumor mortality patterns across doses. No marked strain-related differences in hepatocellular tumor rates were apparent in either sex. Higher frequencies of hepatocellular neoplasms were observed among the untreated control males of the B6C3, AY, and CVA F1 hybrids than among the comparable females. Among treated mice, the lowest 2-AAF dose increased liver tumor incidence, more so among the females than among the males. The different background genomes resulted in somewhat different risk assessments for liver tumor formation in males due to differences in the time-to-tumor curves. Except for the much higher background liver tumor rate in the CVY mice, the adjusted liver tumor incidences were similar across the four hybrids. Hence, the levels of statistical significance obtained for dose-response trends and comparisons of treated and control groups were similar using 48 animals per dose groups with B6C3 mice, or combinations of 24 animals per dose from 2 genotypes, or 12 animals per dose from the 4 hybrid genotypes. Estimates of carcinogenic potency for bladder tumors were similar, within a factor of two, across the four hybrids. However, estimates of liver tumor potency across genotypes varied by a factor of two and six for females and males, respectively. Thus, the mean of cancer potency estimates across these genotypes would be more representative for mice than results from any single genotype. As in chronic carcinogenesis studies with other test agents, neoplasms developed in only a certain proportion, rather than in all, of the genetically identical animals exposed to a given dose of the toxicant for the same length of time under the same controlled environmental conditions. This phenotypic variability in toxic responses may reflect differential regulation of gene expression among the genetically identical test animals.
 ...
PMID:Bladder and liver tumorigenesis induced by 2-acetylaminofluorene in different F1 mouse hybrids: variation within genotypes and effects of using more than one genotype on risk assessment. 185 80

Experimental bladder tumor was reviewed in this paper. Many investigators have been studying on the bladder carcinogenesis since occupational bladder cancers were reported. Main object in research for bladder cancer was to identify and remove environmental causes and various factors related to the development of bladder cancer. Human bladder cancers can be classified into papillary non-invasive and nodular invasive cancer. The establishment of an animal model of bladder cancer similar to human bladder cancer is important to clarify the natural history of this disease and obtain basic data on its clinical diagnosis and treatment. Bladder carcinogenesis has been known to occur in a two-stage process: initiation and promotion. Recently inhibitory effects on the bladder carcinogenesis were also studied. In this paper we described the results that have been obtained in our laboratory concerning animal bladder carcinomas.
 ...
PMID:[Experimental bladder tumor]. 187 65

Authors studied the effects of several biological response modifiers (BRMs) on bladder carcinoma. On carcinogenesis in BBN-induced bladder carcinoma rats, Schizophyllan (SPG) showed inhibition of body weight loss and thymus weight loss. Bladder weight increase was also inhibited. SPG prolonged cancer-bearing survival time, and postponed malignant changes of bladder mucosa. On thymocytes of SPG-treated cancer-bearing rats, rosette-forming thymocytes increased. In clinical study, SPG, OK-432, ubenimex and kampo medicine were used as BRMs. As a result, the number of suppressor-inducer T cells increased, and in cytotoxic T cells a slow fall was observed. On helper-inducer T cells, a slow rise and decrease were noticed in the SPG group, and the reverse tendency was seen in the ubenimex and OK-432 group.
 ...
PMID:Multidisciplinary treatment for bladder carcinoma--biological response modifiers and kampo medicines. 194 64

Bladder tumors were induced in male F344/NCr rats by administration of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) at 500 p.p.m. in their drinking water for 12 weeks. Twenty-one bladder tumors that developed between 25 and 50 weeks after BBN administration was begun were evaluated for immunoreactivity with polyclonal or monoclonal antibodies raised against ras p21, for amplification of ras genes by Southern blotting, and for activating point mutations in ras genes by selective oligonucleotide hybridization of products from polymerase chain reaction (PCR). Increased expression of ras p21 was detected by avidin-biotin immunohistochemistry in 18/21 (85%) of the neoplastic bladder lesions. By Southern analysis, there was no significant amplification of H-ras, K-ras or N-ras in any of the tumors except one that showed a 5-fold amplification of K-ras. Point mutations in ras genes were detected by selective oligonucleotide hybridization of the products of PCR. Of the 21 bladder tumors, three tumors were shown to have mutations in codon 12 (GGA----GAA), six tumors in codon 61 (two CAA----CTA, four CAA----CGA), and one in both codon 12 (GGA----GAA) and codon 61 (CAA----CGA), all in H-ras. Thus 10 of 21 tumors has ras gene mutations in a portion of the tumor cells. The variable pattern of point mutation in H-ras suggests that these mutations may not all be a direct consequence of interaction of BBN metabolites with H-ras. Enhanced expression of ras p21 was always focal and was not necessarily associated with transforming ras mutations. It is therefore suggested that tumorigenesis in BBN-initiated bladder cells might involve H-ras activation as part of a multistep pathway; however, H-ras involvement is not obligatory for tumor development.
Carcinogenesis 1990 Dec
PMID:H-ras activation and ras p21 expression in bladder tumors induced in F344/NCr rats by N-butyl-N-(4-hydroxybutyl)nitrosamine. 226 74

The dog is an animal model for assessing aromatic amine-induced bladder cancer. For this reason, metabolism and disposition of benzidine in dog was assessed. Dogs were administered a 1 mg/kg i.v. dose of [3H]benzidine (16.4 mCi/mmol). The plasma t1/2 of the radiolabeled material (benzidine plus metabolites) was significantly longer (approximately 3 h) than authentic benzidine (less than 30 min). During the 5 h experiment, the majority of radiolabel was associated with bile, urine and carcass. Bladder transitional epithelium exhibited a consistently higher concentration of bound radioactivity than bladder muscle. A significant amount of binding was observed in DNA from liver, kidney and bladder. DNA from bladder transitional epithelium exhibited the highest concentration of radioactivity. Approximately 30% of the radioactivity recovered following HPLC of urine or bile was identified as unmetabolized benzidine. 3-Hydroxybenzidine was a major metabolite identified in bile (8%) but not urine. Urine samples treated with acid, base or sulfatase yielded 3-hydroxybenzidine (6%) as a major hydrolysis product. Similar treatment of bile samples did not result in increased amounts of 3-hydroxybenzidine. Neither N-acetylated nor N-methylated metabolites of benzidine were observed in urine or bile. Thus, considerable metabolism of benzidine occurs in dogs by pathways that are yet to be determined.
Carcinogenesis 1990 Jan
PMID:Metabolism and disposition of benzidine in the dog. 240 56

The effect of oral administration of alpha-difluoromethylornithine (DFMO), an irreversible ornithine decarboxylase inhibitor, on N-butyl-N-(4-hydroxybutyl)nitrosamine (BHBN)-induced rat urinary bladder carcinogenesis was investigated. Four-wk-old male Fischer 344 rats, 30-38 per group, were divided into 3 groups; each group was divided into 3 subgroups. In Group A, 6-wk treatment with 0.05% BHBN in drinking water was followed by either 0.5% (A1), 0.2% (A2), or 0% (A3) DFMO in drinking water for 34 wk. In Group B, coadministration in drinking water of 0.01% BHBN and either 0.5% (B1), 0.2% (B2), or 0% (B3) DFMO was continued for 30 wk. Group C consisted of animals receiving 0.5%, 0.2%, or 0% DFMO in drinking water for 34 wk without prior or cocarcinogen treatment. Bladder tumorigenesis was clearly inhibited by DFMO; tumor incidence was 14 of 37 (38%) in A1, 16 of 38 (42%) in A2, and 31 of 35 (89%) in A3, and 7 of 35 (20%) in B1, 14 of 35 (40%) in B2, and 28 of 35 (80%) in B3 (P less than 0.01, DFMO groups as compared to the respective control A3 or B3). The average tumor volume was strikingly reduced in Group A rats given DFMO (3.0 mm3 in A1, 5.0 in A2, and 38.6 in A3). Significant suppression of tumor multiplicity (number of tumors/tumor-bearing bladder) was observed in DFMO-treated subgroups in Group B (1.1 in B1, 1.3 in B2, and 1.8 in B3). In both Groups A and B, however, DFMO failed to suppress hyperplastic changes (simple hyperplasia) or preneoplastic lesions (nodulopapillary hyperplasia). Systematic examination of all pertinent organs excluding the brain showed no adverse effects attributable to DFMO treatment except for decrease in body weight (less than 7%), which was consistently observed in the groups receiving 0.5% DFMO, and reduction in the combined weight of the prostate and seminal vesicles (less than 20%), which was noted in Group B in which exposure to DFMO was started at a younger age. These results indicate that oral administration of DFMO is quite effective in suppressing (or retarding) BHBN-induced carcinogenesis with minimal untoward effects and confirm the similar inhibitory effects demonstrated earlier with the heterotopically transplanted rat urinary bladder system.
 ...
PMID:Inhibition of N-butyl-N-(4-hydroxybutyl)nitrosamine-induced rat urinary bladder carcinogenesis by alpha-difluoromethylornithine. 311 93

Comparisons of aromatic amine activation were made by using intact cells or cell homogenates (S-9) from bovine bladder urothelium and liver. Since both liver and bladder are thought to contribute carcinogenic metabolites for bladder cancer initiation, comparisons of these two organs' relative ability to activate aromatic amines to mutagens were made. Salmonella typhimurium mutagenesis was used as an indication of mutagen production. Activation occurred in a dose dependent manner and no mutagenic response occurred unless activating cells or S-9 were present. Bladder urothelial cells metabolically activated the carcinogens, 2-amino-fluorene (AF), 2-acetylaminofluorene (AAF), 4-aminobiphenyl (4ABP), benzidine (BZ), and 2-naphthylamine (2NA) but not 1-naphythylamine (1NA), a non-carcinogen. Liver cells were less active than bladder cells in activating AF and AAF; but there was little or no hepatocyte activation of 4ABP, BZ, 2NA and 1NA. Intact bladder cells were more effective than bladder S-9 in activating AAF, but not in activating AF, 4ABP, BZ and 2NA. The liver S-9 showed more mutagenic activity with AF than did intact liver cells; the reverse was true for AAF, and bovine liver S-9 showed little or no activation of 4ABP, BZ, and 2NA. 1NA was not activated by either S-9 preparation. As was the case for intact cells, bladder S-9 was more effective than liver S-9 in activating the aromatic amines studied. The results demonstrate the capacity of bovine bladder urothelium to metabolically activate aromatic amines and suggest a role for the target organ itself in carcinogen activation. Information on the relative usefulness of intact cells versus S-9 preparations as activation systems was also obtained from these studies.
Carcinogenesis 1983 Nov
PMID:Bovine bladder and liver cell and homogenate-mediated mutagenesis of Salmonella typhimurium with aromatic amines. 635 20

Chemical carcinogenesis is currently regarded as a complicated series of events requiring initiation and promotion in specific sequences. Carcinogens are thought to be chemicals which can induce both initiation and promotion so that few if any additional host or environmental factors are required in the production of neoplasms. Most experimental studies to date have investigated bladder cancer using these highly active agents and the role of other substances in urothelial neoplasia has not been emphasized. We have examined the role of a variety of solutions, including water and saline, in pilot studies of urothelial carcinogenesis using the ALZA mini-pump for continuous infusion. Bladder tumors indistinguishable morphologically from papillary transitional cell carcinomas were induced. Although experimental induction of bladder cancer with powerful carcinogens may completely overwhelm host defenses and result in more and higher grade neoplasms, similar tumors may occur after exposure to substances not generally considered to be carcinogenic. This process, which probably requires cofactors and host-chemical interaction, may be more representative of environmental carcinogenesis than systems using powerful carcinogens and should be further investigated.
 ...
PMID:Bladder cancer induced by noncarcinogenic substances. 641 95


1 2 3 4 5 Next >>