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PubMed1983

Enhanced macromolecular binding of N-[4-(5-nitro-2-furyl)-2-thiazolyl]- formamide in germfree versus conventional rats.

To investigate the binding of a nitrofuran to tissue macromolecules in vivo, the urinary bladder carcinogen N-[4-(5-nitro-2-furyl)- 2-[35S]thiazolyl]formamide [[35S]FANFT; 94 mCi/mmol] was given p.o. to conventional [n = 4; 115 +/- 8 g (S.D.)] and germfree [n = 4; 105 + 5 g] female CD rats [1.23 mCi/rat]. After 18 hr, organs were removed, and macromolecules were then isolated from individual livers and kidneys and from pooled urinary bladders. A hydroxylapatite isolation procedure was followed (Beland et al., J. Chromatogr., 174: 177-186, 1979), and the nucleic acids obtained were further purified by digestion with appropriate nucleases and/or centrifugation (105,000 X g). The results are as follows and are given in pairs (conventional/germ-free) expressed as pmol FANFT bound per mg macromolecule. Protein binding levels were: liver, 165 +/- 40/307 +/- 31; kidney, 72 +/- 19/88 +/- 24; bladder, 272/322. RNA levels were: liver, 217 +/- 184/413 +/- 196; kidney, 219 +/- 60/617 +/- 196; bladder, 448/1373. DNA levels were: liver, 9.8 +/- 7.5/17.0 +/- 7.5; kidney, 0.69 +/- 0.38/4.5 +/- 1.0. The quantity of bladder DNA was insufficient for accurate measurement. Diethylaminoethyl cellulose chromatography of liver RNA from a germfree rat, either before or after RNase digestion, showed that the majority of the radioactivity was associated with a polynucleotide fraction that appeared to be RNase resistant and accounted for only a small portion of the total RNA but that also permitted the intercalation of ethidium bromide. The deformylated FANFT metabolite, 2-amino-4-(5-nitro-2-fury)thiazole, reacted with transfer RNA upon reduction with sodium dithionite in vitro to give adduct(s) that also appeared to be RNase resistant. Thus, these results show that the urinary bladder carcinogen FANFT or its metabolites react in vivo with protein and nucleic acid of both target and nontarget organs and that binding levels are elevated in germfree rats.

Animals↗
PubMed1980

Early induction of mouse urinary bladder ornithine decarboxylase activity by rodent vesical carcinogens.

The responses of mouse urinary bladder ornithine decarboxylase (EC 4.1.1.17) and S-adenosyl-L-methionine decarboxylase (EC 4.1.1.50) activities were studied following topical intravesical administration of N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide (FANFT) or 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT), potent rodent bladder carcinogens. A single bladder topical application of ANFT or FANFT resulted in a significant increase over controls of ornithine decarboxylase activity within 5 hr, with a return to control levels by 10 hr. S-Adenosyl-L-methionine decarboxylase activity demonstrated a lesser response to topical ANFT or FANFT, achieving a level 2 or 3 times that of controls at 5 to 8 hr, followed by a gradual decline to control levels. Stimulation of activities of both enzymes was dose dependent over a range of 4.6 to 460 nmol of ANFT. ANFT-induced ornithine decarboxylase activity was principally localized in the bladder epithelium and was inhibited in a linear dose-response relationship by the synthetic retinoid, 13-cis-retinoic acid. Mice given FANFT p.o. demonstrated a significant increase over controls in ornithine decarboxylase activity within 12 hr, followed by a gradual decline to control levels by 72 hr.

Adenosylmethionine Decarboxylase↗
PubMed1976

Mutagenic activity of carcinogenic and noncarcinogenic nitrofurans and of urine of rats fed these compounds.

The nitrofurans, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2), N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT), nitrofurantoin, 5-nitro-2-furoic acid, 5-nitro-2-furamidoxime, 5-nitrofurfurylidene diacetate and the urine of rats fed these compounds, were assayed for mutagenic activity in Salmonella typhimurium strains TA100 and TA100FR1. All the nitrofurans were mutagenic in the order: AF-2 and FANFT greater than nitrofurantoin greater than 5-nitro-2-furamidoxime greater than 5-nitrofurfurylidene diacetate greater than 5-nitro-2-furoic acid. Strain TA100 was more sensitive than TA100FR1 to the mutagenic influence of these nitrofurans. Only the urine of rats fed AF-2, FANFT and nitrofurantoin had mutagenic activity. Again, TA100 was more sensitive than TA100FR1. The mutagenicity of the urine was not increased by treatment with beta-glucuronidase. AF-2, 2-amino-4-(5-nitro-2-furyl)thiazole (deformylated product of FANFT) and nitrofurantoin were excreted in the urine of rats fed these compounds; whereas the other nitrofurans were not excreted.

Animals↗
PubMed1983

Prostaglandin hydroperoxidase-catalyzed activation of certain N-substituted aryl renal and bladder carcinogens.

Certain carcinogens are thought to induce renal and bladder cancer following metabolic activation. We propose a model system for this activation and provide supporting experimental evidence. This model proposes that renal and bladder carcinogens' entry into the urinary tract is facilitated, that carcinogens are activated by the prostaglandin hydroperoxidase activity of prostaglandin endoperoxide synthetase (PES), and that activation results in covalent binding to nucleic acids which can initiate carcinogenesis. Benzidine and the 5-nitrofuran HMN were shown to inhibit uptake of organic anions and cations, respectively. Carcinogen binding to DNA was dependent upon specific unsaturated fatty acid substrates and prevented by specific inhibitors of PES, i.e., aspirin. Activation with organic peroxides or H(2)O(2) was inhibited by antioxidants but not aspirin. Horseradish peroxidase (HRP) metabolized benzidine but not ANFT. Acetaminophen and the 5-nitrofurans ANFT and HMN prevented PES (14)C-benzidine metabolism. However, only acetaminophen inhibited HRP metabolism of benzidine. The only aerobic metabolism we have observed of 5-nitrofurans is PES-catalyzed. Aspirin (0.5% in the diet) inhibited rat bladder hyperplastic lesions induced by feeding 0.1% or 0.2% FANFT for 6 or 12 weeks. Aspirin reduced bladder prostaglandin synthesis and PES metabolism of FANFT. After one year of an ongoing long-term study, gross examination reveals bladder tumors in 85% of the rats fed 0.2% FANFT and in only 37% of the rats fed FANFT plus 0.5% aspirin.

Amines↗
PubMed1976

A simple method for detection and analysis of carcinogenic nitrofuran compounds and their metabolites by combining chromatography and spot mutation tests.

A simple, sensitive, and convenient method combining thin-layer chromatography and a spot test for mutagenicity of Salmonella typhimurium TA100 was utilized for the analysis of urine of rats fed N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide (FANFT), a potent experimental urinary bladder carcinogen. Three metabolites of FANFT were detected in urine, and one of these, accounting for 33% of the urinary metabolites of FANFT, was identified as 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT). ANFT was the only urinary metabolite that clearly demonstrated mutagenic activity, suggesting that ANFT may be a proximate vesical carcinogen of FANFT.

Animals↗
PubMed1976

Experimental bladder tumor induction, propagation, and therapy.

The development of animal bladder tumor models as a research tool for different modes of therapy has been widely evaluated. Recently these tumors have either spontaneously grown or have been propagated in inbred strains. Bladder tumors have also been chemically produced by N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) when orally administered over a long period of time. It has been further reported that these tumors have been inhibited by various chemotherapy regimens. The availability of an experimental bladder tumor model offers an opportunity to evaluate the effectiveness of a prescribed treatment. In our studies FANFT was noted to produce only from 33 to 40% bladder tumors in several experiments in an inbred strain of rats conducted over several years. Reproducible transplantability of these tumors was not demonstrable in the same inbred strain. In addition, treatment with mitomycin C an an effective chemotherapeutic agent was not detectable in part, since comparably the percentage of control bladder tumor growth was low. These findings of a three-year study should be carefully considered when evaluating recommendations for clinical adjuvant chemotherapy based on results obtained with FANFT.

Administration, Oral↗
PubMed1983

Effect of phenobarbital on the carcinogenesis of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide in rats.

Male Fischer rats were fed a N-[4-(5-nitro-2-furyl]-2-thiazolyl]formamide (FANFT) diet for 6 weeks followed by a phenobarbital (PB) diet for an additional 86 weeks. PB significantly increased the incidence of bladder tumors, but not the incidence of hepatic foci and areas of cellular alterations caused by FANFT. The results suggest that PB may be a weak promoter for bladder carcinogenesis, and that FANFT may not be an initiator for hepatocarcinogenesis.

Animals↗
PubMed1987

The influence of urinary tract infection on the incidence of urinary tract tumors in N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide induced carcinogenesis in male Sprague-Dawley rats.

Epidemiological studies have demonstrated an association between urinary tract infection and the development of bladder cancer. The present study aimed at evaluating the influence of urinary tract infection in male Sprague-Dawley rats exposed to a sub-carcinogenic dose of N-[4-(nitro-2-furyl)-thiazolyl]formamide (FANFT). A single injection of Escherichia coli into the bladder resulted in a persistent upper urinary tract infection in a high percentage of the rats. Thirty-two percent of the rats exposed to FANFT and E. coli infection developed urinary tract tumors, all but one occurring in the renal pelvis. Urinary tract tumors were not found in rats treated with FANFT or E. coli alone. The present results support that inflammation resulting from infection is actively involved in urinary tract tumorigenesis and may support the epidemiological studies showing an association between infection and human urinary tract cancer. The formation of dimethylnitrosamine or other nitroso compounds from nitrates in the urine or increased cell proliferation due to chronic inflammation or both may be important pathogenetic factors in tumor development.

Animals↗
PubMed1990

Metabolism of aromatic and heterocyclic amine bladder carcinogens: bioanalytical considerations.

Aromatic and heterocyclic amines are environmental chemicals which can cause bladder cancer in man. Because these chemicals cause carcinomas at a site distal to their portals of entry, metabolic processes are involved in initiation of their carcinogenic effects. N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) and its deformylated analogue, ANFT, were used as model compounds to assess metabolism. Electrochemical properties of ANFT made liquid chromatography with electrochemical detection a specific and sensitive method for analysis. Peroxidatic metabolism of ANFT by prostaglandin H synthase (PHS) in the presence of N-acetylcysteine resulted in the formation of 2-amino-4-(5-nitro-2-furyl)-5-(N-acetylcystein-S-yl)thiazole (ANFT-MA). This thioether product has an oxidation potential significantly lower than ANFT. Rat urinary excretion of ANFT-MA was significantly decreased with peroxidase inhibitors, 6-n-propyl-2-thiouracil and methimazole. Inhibitors did not alter excretion of ANFT or prostaglandin E2, a PHS product of arachidonic acid metabolism. 1H and 13C-NMR were selected to explore potential structural differences between ANFT and FANFT which might explain preferential PHS metabolism of ANFT. Evidence for a "zwitterion" configuration for ANFT but not FANFT was observed. ANFT in the "zwitterion" configuration would be a better reducing co-substrate. Chemical synthesis and GC-MS fragmentation patterns identified 3-(2,3-dihydro-1-methyl-2-pyrrolyl)pyridine as a peroxidatic product of nicotine metabolism. This peroxidatic product was found in urine from a cigarette smoker in an amount approximately 6% that observed for continine. Thus, a potential rôle for peroxidative metabolism was demonstrated in man.

Animals↗
PubMed1998

Tumor versus vascular photodamage in a rat tumor model.

The [4-(5-nitro-2-furyl)-2-thiazoyl] formamide (FANFT)-induced urothelial tumor in the rat is found to express the mdr gene. The resulting multidrug resistance (MDR) phenotype results in the expression of an outward transport system that prevents cellular accumulation of certain weakly cationic agents. Among the latter is a photosensitizer with known efficacy for the FANFT tumor, the copper benzochlorin iminium salt. FANFT cells are protected from direct cell kill mediated by this drug, suggesting that the substantial delay in tumor regrowth from this tumor/sensitizer combination can be attributed to vascular effects.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1984

A general probabilistic model of carcinogenesis: analysis of experimental urinary bladder cancer.

A theoretical model of two-stage carcinogenesis has been hypothesized. Variables that are modeled include the populations of normal, initiated, and transformed cells; mitotic rates of these cells; hyperplasia; and the probabilities of cell initiation and transformation during replication. The size of the cell populations can be estimated and mitotic rates determined directly from animal studies. Tumor occurrences at different time intervals following varying periods of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) and sodium saccharin administration are known and are used in the indirect estimation of values for unobservable model variables. Model-based analyses suggest FANFT markedly increases the probability of cell initiation in addition to its experimentally verifiable effects on increasing the stem cell population and mitotic rates. Further, experimental results appear inconsistent with the hypothesis that FANFT increases the probability of cell transformation over background levels. Similarly, the effect of sodium saccharin was found to be attributable entirely to increases in stem cell populations and mitotic rates without influencing either the probability of initiation or the probability of transformation.

Animals↗
PubMed1976

Light and scanning electron microscopy of exfoliated bladder epithelial cells in rats fed N-(4-(5-nitro-2-furyl)-2-thiazolyl)formamide.

Urine specimens obtained periodically from weanling male F344 rats fed 0.2% N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) for 25 weeks followed by control diet for an additional 35 weeks, were examined by light microscopy (LM) and scanning electron microscopy (SEM). LM revealed red blood cells and atypical transitional cells in the urine at 25 and 43 weeks, when microinvasive transitional cell carcinoma was present. Malignant transitional cells were seen in the urine by LM at 60 weeks, when muscle invasion was present in histologic sections. However, SEM showed pleomorphic microvilli on exfoliated urothelial cells as early as 10 weeks after the beginning of FANFT administration, and the microvilli became increasingly pleomorphic as the bladder lesions progressed to muscle invasion at 60 weeks. Noninvasive tumors were present in histologic sections of rat bladders examined at the end of 10 weeks of FANFT administration. The numerous microvilli on exfoliated bladder tumor cells were in sharp contrast to the peaked microridges of normal exfoliated superficial cells.

Animals↗
PubMed1983

Promotion in urinary bladder carcinogenesis.

Aromatic amines, including 2-naphthylamine, 4-aminobiphenyl and benzidine, are known urinary bladder carcinogens in man and other species, but in rodents, aromatic amines and amides have usually induced liver tumors, occasionally also with tumors of the bladder and other tissues. Variations in organ specificity are related to differences in metabolism; for the production of bladder tumors, the rates of acetylation and deacetylation appear to be critical. Bladder specific carcinogens in rodents and other species have subsequently been identified, including N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) administered in the drinking water, N-[(4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) in the diet and N-methyl-N-nitrosourea (MNU) instilled intravesically. When low doses of several bladder carcinogens (BBN, FANFT, 2-acetylaminofluorene, and 3,3'-dichlorobenzidine) are administered to rats, either simultaneously or sequentially, a synergistic effect is observed with respect to bladder carcinogenesis. In addition, a multistage carcinogenesis process has been demonstrated for the rat bladder using MNU or FANFT as initiators, and dietary sodium saccharin, sodium cyclamate, or tryptophan as promoters. Calculi (or pellets) appear to enhance the promotion process but are not necessary for it to occur. Recent studies also indicate that urine has a role in the promoting process. The urothelium normally has a very low mitotic rate. If mucosal proliferation is increased, such as during fetal development or during regeneration and repair of an ulcer, the bladder appears to be considerably more sensitive to the effects of promoting substances. For example, if sodium saccharin is administered to rats after ulceration of the bladder, even without prior administration of an initiator, bladder carcinoma develops. Under these conditions, the substance appears as a carcinogen. Human populations with increased bladder epithelial proliferation, such as fetus, infants, patients with bacterial cystitis or men with partially obstructive prostatism, may have increased susceptibility to the action of carcinogenic or promoting stimuli.

Animals↗
PubMed1992

Acrolein initiates rat urinary bladder carcinogenesis.

Acrolein, a reactive, alpha,beta-unsaturated aldehyde which is ubiquitous in the environment, forms DNA adducts, is mutagenic, and is teratogenic. However, studies have not indicated a carcinogenic effect in rodent bioassays. Since it is present in cigarette smoke and is the toxic metabolite of cyclophosphamide with respect to the urinary tract, we investigated the possibility that acrolein might have carcinogenic activity toward the rat urinary bladder. We also evaluated whether it possessed initiating and/or promoting activity. To evaluate initiating activity, acrolein was administered at a dose of 2 mg/kg i.p. twice a week for 6 weeks followed by uracil as 3% of the diet for 20 weeks and then control diet for 6 weeks. N-[4-(5-Nitro-2-furyl)-2-thiazolyl]formamide (FANFT) as 0.2% of the diet followed by uracil was used as a positive control, and a negative control group was administered solvent control (water) i.p. during the 6-week initiation period followed by uracil. Acrolein followed by uracil produced an incidence of 18 of 30 rats (60%) with papilloma compared to 8 of 30 rats (27%) treated with solvent control followed by uracil. FANFT followed by uracil produced an incidence of 70% carcinomas and 30% papillomas, clearly indicating that it is a much more potent initiating agent than acrolein. Acrolein for 6 weeks followed by control diet produced no tumors. To evaluate promoting activity, groups of rats were fed FANFT for 6 weeks followed by acrolein. Acrolein administered during the initial 6 weeks and continued for the second phase of the experiment (to evaluate complete carcinogenic activity) resulted in severe toxicity. Administration of acrolein had to be terminated after 21 weeks of the experiment. The animals were maintained for 53 weeks of the experiment without further chemical treatment, and there was no evidence of papilloma or carcinoma development. This study clearly indicates that acrolein has initiating activity for the urinary bladder when administered by i.p. injection to the male F344 rat, but toxicity precluded evaluation of its promoting or complete carcinogenic activity.

Acrolein↗
PubMed1990

Protection from carcinogen-induced murine bladder carcinoma by interferons and an oral interferon-inducing pyrimidinone, bropirimine.

Interferons (IFNs) have established activities as antivirals and inhibitors of viral and transplantable tumors. To establish whether IFNs or their inducers can affect induction of carcinogenesis in vivo, the bladder-specific carcinogen N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) was administered in the diet at 0.11 or 0.13% (w/w) to female C3H/He mice beginning at 7 weeks of age. Mice treated with the IFN-inducing bropirimine [2-amino-5-bromo-6-phenyl-4(3H)-pyrimidinone] i.p. twice a week for 14 weeks starting on day 30 of start of FANFT feeding developed fewer transitional cell carcinomas (TCC) than mice treated with the vehicle. Bropirimine (200 mg/kg twice a week) orally resulted in even greater effectiveness: 6 of 43 bladders with TCC for bropirimine-treated mice versus 24 of 39 for control glycine buffer-treated mice (P less than 0.01, x2 test). Mice treated i.p. daily on days 29 through 210 with 5,000 units of beta interferon (specific activity, 2.0 x 10(8) units/mg) had 0 of 15 TCC while control mice had 7 of 13 TCC (P less than 0.001). Bladders of untreated mice were also significantly heavier than those of beta interferon- or bropirimine-treated mice. This dose of IFN treatment was confirmed as effective in a second experiment, in which mice were treated daily on days 30-223 with 5,000 units alpha/beta interferon (specific activity, 1.2 x 10(7) units/mg). This resulted in 4 of 25 bladders with TCC versus 24 of 39 for control mice (P less than 0.001). A higher dose of IFN (50,000 units alpha/beta interferon daily) was toxic; 24 of 30 mice died within 2 months. IFN and an IFN inducer, bropirimine, inhibited development and progression of FANFT-induced bladder TCC in vivo and thus may have roles as chemopreventive modalities.

Animals↗
PubMed1985

Low susceptibility of analbuminemic rats to induction of bladder cancer by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide.

The susceptibility of analbuminemic rats (Nagase analbuminemic rats; NAR) to induction of bladder cancer by oral N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) was studied. Male NAR and Sprague-Dawley rats (SD) were fed normal diet or normal diet supplemented with 0.2% FANFT for 10 weeks and killed in week 52. Bladder cancer was found in 5 of 24 SD (21%) but not in 18 NAR (0%). Proliferative lesions of the bladder epithelium, which are considered to be precancerous or more advanced than precancerous changes, were found in 16 of 24 SD (67%), but in only 4 of 18 NAR (22%). NAR showed lower susceptibility than control SD to induction of bladder cancer by FANFT.

Animals↗
PubMed1979

Retinyl acetate prophylaxis in cancer of the urinary bladder.

Virgin female C3H/He mice (275) were fed a ration that included 0.1 per cent N-4-(5-nitro-2-furyl)-2-thiazolyl formamide (FANFT) and retinyl acetate. The mice were divided into five groups with Groups 1 through 4 receiving 300, 600, 1200, and 2400 IU of retinyl acetate per kilogram of feed plus FANFT respectively. Group 5 received 300 IU per kg of feed and no FANFT as a control. After 45 weeks the bladders were removed and inspected for neoplasms. There were no tumors found in any of the mice from Group 5. It was found that retinyl acetate significantly inhibited the formation of squamous cell tumors at all levels and inhibited transitional cell carcinoma when given as 600 IU per kilogram of feed.

Animal Feed↗
PubMed1975

Focal loss of alkaline phosphatase and increase of proliferation in preneoplastic areas of the rat urothelium after administration of n-butyl-n-(4-hydroxybutyl)-nitrosamine and n-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide.

Development of tumours of the urinarY bladder was studied in 59 Male and female Sprague-Dawley and Wistar rats with combined enzyme-histochemical and autoradiographic methods after oral application of n-butyl-n-(4-hydroxybutyl)-nitrosamine (BBN) and n-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT). as the first carcinogenic lesion detectable by light-microscopy a focal, sharply defined irreversible loss of alkaline phosphatase activity was consistently demonstrated in the urothelium, which appeared normal histologically and cytologically. In about 2/3 of the cases, NADH-diaphorase activity was markedly reduced in identical regions. The enzyme-deficient areas are to be considered as preneoplastic, because papillomas and carcinomas developed from them through different stages of hyperplasia. As a rule, these also were characterized by total loss of alkaline phosphatase activity and attenuation of the NADH-diaphorase in all parts or circumscribed areas. Autoradiographically 3H-thymidine-labelling index revealed a 43.2-fold (BBN) and 22.6-fold (FANFT) increase, respectively, in the enzyme-deficient areas, as compared with the surrounding emzyme-containing urothelium. After 54 hrs of continous labelling, there was a mean 3H-thymidine-labelling index of 54.9% in the enzyme-negative regions. The physiological mode of regeneration was no longer maintained in the areas of enzyme deficiency as there was an increased proliferation of suprabasal cells. Areas of papillomas that showed a marked attention of NADH-diaphorase had a 3H-thymidine-labelling index 4.5 (BBN) and 3.1 (FANFT) greater than the surrounding areas with preserved enzyme activity. Since loss of alkaline phosphatase activity occurs regulary and consistently after application of carcinogens with chemically different structures it appears to indicate the initial phase of tumor development in the urinary bladder of the rat.

Administration, Oral↗