Existence of a Threshold for Induction of Aberrant Crypt Foci in the Rat Colon with Low Doses of 2-Amino-1-methyl-6-phenolimidazo[4,5-b]pyridine

Until recently it has been generally considered that genotoxic carcinogens have no threshold in exerting their potential for cancer induction. However, the nonthreshold theory can be challenged with regard to assessment of cancer risk to humans. In the present study we show that a food derived, genotoxic hepatocarcinogen, 2-amino-1-methyl-6-phenolimidazo[4,5-b]pyridine (PhIP), does not induce aberrant crypt foci (ACF) as preneoplastic lesions at low dose (below 50 ppm) or 8-hydroxy-2'-deoxyguanosine (below 400 ppm) in the rat colon. Moreover PhIP-DNA adducts were not formed at the lowest dose (below 0.01 ppm). Thus, the dose required to initiate ACF is approximately 5000 times higher than that needed for adduct formation. The results imply a no-observed effect level (existence of a threshold) for colon carcinogenesis by a genotoxic carcinogen.

Inhibition by ginseng of colon carcinogenesis in rats

The inhibitory effects of ginseng on the development of 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) in the colon were investigated in rats. Male, 6-week-old rats were injected with DMH once a week for 4 weeks. Rats in Groups 1 and 2 were fed diets containing red and white ginseng, respectively, at a dose of 1% for 5 weeks, starting one week before the first treatment of DMH. Animals in Groups 3 and 4 received red or white ginseng for 8 weeks starting after DMH treatment. Group 5 served as a carcinogen control group. Numbers of ACF with at least four crypts were significantly reduced in the colon of Group 2 treated with red ginseng combined with DMH. Moreover, rats were injected with DMH 4 times at one-week intervals. They were also fed diets containing 1% red or white ginseng or the control diet throughout 30 days of the experiment. Treatment with red ginseng resulted in a significant decrease of 5- bromo-2'-deoxyuridine labeling indices in colonic crypts comprising ACF. These findings suggest that dietary administration of red ginseng in combination with DMH suppresses colon carcinogenesis in rats, and the inhibition may be associated, in part, with inhibition of cell proliferation, acting on ACF in the colonic mucosa.

p53 and H-ras mutations and microsatellite instability in renal pelvic carcinomas of NON / Shi mice treated with N-butyl-N-(4-hydroxybutyl)-nitrosamine: different genetic alteration from urinary bladder carcinoma

We previously reported p53 mutations to be frequent (greater than 70%), whereas both H-ras mutations and microsatellite instability (MSI) were infrequent (about 10%), in urinary bladder carcinomas (UBCs) and their metastatic foci in the N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced mouse urothelial carcinogenesis model. In the present study, an analysis of p53 and H-ras mutations as well as MSI was performed on 12 renal pelvic carcinomas (RPCs) and 8 metastatic or invading foci produced by the same experimental procedure. Histologically, 10 of the RPCs were transitional cell carcinomas and the remaining 2 were squamous cell carcinomas. p53 mutations were infrequent and only found in one primary RPC (8%), its metastatic foci and an invading lesion in another animal (in a total 2 of 12; 17%). H-ras mutations were slightly more frequent (found in 3 of 12 animals; 25%), 4 of 5 involving codon 44, GTG to GCG, not a hot-spot reported for human cancers. In two cases, H-ras mutations were confined to lung metastasis and not detectable in their primary RPCs. MSI analysis was available for 6 pairs of primary RPCs and their metastatic foci, and 4 animals (67%) had MSI at one or more microsatellite loci. Overall, the distribution of genetic alterations differed from that in UBCs produced by the same experimental protocol. The results thus suggest that different genetic pathways may participate in carcinogenesis of the upper and lower urinary tract due to BBN.

Lack of change in the levels of liver and kidney cytochrome P-450 isozymes in p53+/- knockout mice treated with N-butyl-N-(4-hydroxybutyl)nitrosamine

We have previously shown that p53(+/-) knockout mice are highly sensitive to urinary bladder carcinogenesis induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in spite of a lack of effects of p53 heterozygosity on N-butyl-N-(3-carboxypropyl)nitrosamine (BCPN) excretion in urine. To determine the influence of p53 deficiency on in vitro formation of BCPN, mutagenicity of BBN and BCPN and levels of several cytochrome P450 (CYP) isozymes, groups of five p53(+/-) knockout and wild-type mice (littermates), as well as animals of the C57BL/6 parental strain, were administered 0.025% BBN in their drinking water for 4 weeks. The livers and kidneys were then used for analyses of BBN metabolism, western immunoblotting and Ames liquid incubation. BBN treatment caused a slight decrease in BCPN formation in the livers of C57BL/6 mice, but there was no significant difference between p53 knockout, wild-type and C57BL/6 mice. In kidney BCPN formation in p53 knockout mice was 33-46% less than that in their wild-type counterparts. Using anti-rat CYP antibodies, CYP1A2, 2B9/10, 2E1 and 3A11/13 were constitutively detected in liver microsomes and CYP2E1 and 3A11/13 in the kidney. Densitometric determination of these CYP proteins revealed no significant variation in levels detected in both tissues among the four groups of mice. BBN and BCPN were not mutagenic for Salmonella typhimurium TA100 in either the absence or presence of liver S9 from untreated mice and rats and from p53 knockout mice treated with BBN. In conclusion, p53 deficiency and BBN had no enhancing effects on metabolism of BBN to BCPN and expression of the CYP isozymes typically responsible for activation of environmental carcinogens, including both of the N-nitrosamines tested, and their mutagenicity, indicating that the high susceptibility of p53(+/-) knockout mice is not attributable to metabolic activation in liver and kidney by CYP isozymes or urinary excretion of BCPN.

Renal pelvic carcinoma producing granulocyte colony-stimulating factor: report of a case

A 69-year-old man was admitted to our hospital because of anorexia and weight loss. Abdominal computed tomography showed an irregularly contoured mass in his left renal pelvis. The patient had a remarkable degree of leukocytosis with no obvious focus of infection. An enzyme immunoassay of the serum revealed a remarkably high concentration of granulocyte colony-stimulating factor (G-CSF). The patient died 6 weeks after admission without a resection of the renal pelvic tumor. At autopsy, the tumor involved the pancreas, stomach, and descending colon. The histopathologic diagnosis was squamous cell carcinoma with sarcomatous change. Immunohistochemical staining using anti-G-CSF antibody demonstrated immunoreactivity in the cancer cells. To our knowledge, this is the first case of renal pelvic carcinoma proven to produce G-CSF reported in English.

Long-term survival after resection for small cell carcinoma of the esophagus

We describe the rare case of a patient with esophageal small cell carcinoma who was completely cured. A 77-year-old man had small cell carcinoma of the esophagus with extensive lymph node metastases. Treatment comprised a subtotal esophagectomy and extended lymph node dissection. He has survived for more than 7 years with no evidence of recurrent disease. We suggest that radical operations should be considered for future patients if curative resection can be expected.

Promotion of chemically induced rat esophageal tumorigenesis with post-initiation ethanol modification

Post-initiation ethanol modification on N-nitrosomethylbenzylamine (NMBA)-induced rat esophageal carcinogenesis model was investigated in male, 6-week-old, F344 rats that received s.c. injections, 3 times per week, of 0.5 mg/kg NMBA for the first 5 weeks and then were treated with 0% (Group 1), 3.3% (Group 2), and 10% (Group 3) ethanol in the drinking water for up to 20 weeks. Group 4 received 10% ethanol without NMBA administration and Group 5 was maintained without any chemical treatment. There were no statistical differences in the incidence and multiplicity of esophageal tumors among Groups 1 to 3. However, the multiplicity of hyperplasias was statistically greater in Group 3 than in Groups 1 or 2. Esophageal epithelia of all rats in Groups 4 and 5 demonstrated a normal histology. BrdU labelling indices of tumors and hyperplasias in NMBA-treated groups were essentially similar, although cycline D1 was overexpressed to a greater extent in tumors and also hyperplasias of Group 3 than in Groups 1 or 2. The results indicated ethanol to exert weak promotion effects through cycline D1 overexpression on rat esophageal tumorigenesis initiated with NMBA.

Possible prevention by abieslactone of development of diethylnitrosamine-initiated GST-P positive foci in the rat liver

Triterpenoid compounds, isolated from plants of Abies genus (Pinceae), are known to exert anti-tumor promotion activities in mouse skin carcinogenesis. In the present study, we investigated whether AVB-1 and acid and acid methyl ester derivatives have inhibitory effects on rat hepatocarcinogenesis by using a liver medium-term bioassay for carcinogens (Ito's test), immunohistochemically assessing the numbers and areas per cm(2) of preneoplastic lesions, glutathione S-transferase placental form (GST-P)-positive foci. In experiment 1, 6-week-old male Fisher 344 rats were given a single intraperitoneal injection of diethylnitrosamine (200 mg/kg b.w.) and subjected to two-thirds partial hepatectomy at week 3. From weeks 2 to 8, the compounds were given three times a week at a dose of 1 mg/kg b.w. by i.g. gavage and found to significantly decrease the number of GST-P-positive foci in the liver. In experiment 2, AVB-1 was given three times a week at doses of 3, 1, or 0.3 mg/kg b.w. by i.g. gavage from weeks 2 to 8. All doses of AVB-1 significantly decreased the numbers of GST-P-positive foci. Thus, our results suggest that AVB-1 is a chemopreventive agent for rat hepatocarcinogenesis.

Dimethylarsinic acid induces 8-hydroxy-2'-deoxyguanosine formation in the kidney of NCI-Black-Reiter rats

Dirnethylarsenic peroxyl radical [(CH(3))(2)AsOO] has been postulated to be responsible for DNA damage induced by dimethylarsinic acid (DMA). In an effort to elucidate the possible mechanism of tumor-inducing potential of DMA, an experiment was designed to investigate the formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a specific marker of oxidative base damage in the kidney tissues of NCI-Black Reiter (NBR) rats. Animals were divided into four groups and administered the vehicle - saline, 5, 10 and 20 mg/kg body weight respectively of DMA by gavage, once a day, 5 days a week, for a period of 4 weeks. DMA induced increase of 8-OHdG levels in the kidney of the rats treated, with the highest level at the dose of 10 mg/kg body weight. Analysis of the kidney for cell proliferation employing PCNA-positive index showed greater proliferation in the tissues of treated rats. However, DMA did not have any influence on apoptosis in this regimen. Histopathological examination of the kidney selections revealed the presence of vacuolated degeneration and dilation of the proximal tubule cells in two groups (10 and 20 mg/kg body weight). This study provides evidence to substantiate the role of DMA in inducing oxidative DNA damage in the kidney.

Suppression of chemical carcinogenesis by water-soluble organosulfur compounds

The chemopreventive effects of five water-soluble organosulfur compounds, S-methylcysteine (SMC) and four analogs, were examined on the promotion stage of diethylnitrosamine hepatocarcinogenesis in male F344 rats, using the medium-term bioassay (Ito test), which is based on the two-step model of hepatocarcinogenesis. In addition, we investigated the modifying effects of SMC and cysteine on the initiation stage of rat hepatocarcinogenesis. Carcinogenic potential was scored by comparing the numbers and areas of a putative neoplastic lesion, glutathione S-transferase placental form (GST-P)--positive hepatocellular foci. SMC and cysteine significantly decreased the number and area of GST-P--positive foci when given in the promotion stage of the Ito test. When given during the initiation stage, these two organosulfur compounds also significantly inhibited focus formation. Liver ornithine decarboxylase activity after two thirds partial hepatectomy and the proportion of hepatocytes positive for proliferating cell nuclear antigen significantly decreased the number of aberrant crypt foci in the colon in a multiorgan carcinogenesis bioassay of rats. These results support SMC and cysteine as chemopreventive agents for hepatocarcinogenesis and colon carcinogenesis. Their intake may be of importance for cancer.

Presence of a no-observed effect level for enhancing effects of development of the alpha-isomer of benzene hexachloride (alpha-BHC) on diethylnitrosamine-initiated hepatic foci in rats

The dose dependence of the promoting effects of the alpha-isomer of benzene hexachloride (alpha-BHC) on hepatocarcinogenesis was investigated in a medium-term rat liver bioassay (Ito test). A total of 195 F344 male rats, 6 weeks old, were given a single intraperitoneal injection of diethylnitrosamine (DEN) at the start of the experiment and subjected to two-thirds partial hepatectomy at week 3. Two weeks after the administration of DEN, alpha-BHC were fed to rats at doses of 0, 0.01, 0.1, 0.5, 1, 2, 4, 7.5, 15, 30, 60, 125 and 500 ppm in diet for 6 weeks. All surviving animals were killed at week 8, and their livers were examined immunohistochemically for detection of glutathione S-transferase placental form (GST-P)-positive foci, surrogate preneoplastic lesions. Quantitative values for numbers and areas were dose-dependently increased in rats given alpha-BHC at 0.5-500 ppm. However, those for groups treated with 0.01 and 0.1 ppm were decreased, albeit not significantly in comparison to the controls. Cytochrome P450 3A2 (CYP3A2) protein levels and activities showed a good correlation to the number and area of GST-P-positive foci. These results support evidence of hormesis and indicate a no-observed effect level for alpha-BHC promoting potentials may exist regarding rat liver carcinogenesis, which correlates with expression of CYP3A2 in the liver.

Chemopreventive effects of S-methylcysteine on rat hepatocarcinogenesis induced by concurrent administration of sodium nitrite and morpholine

The aim of the present study was to examine the chemopreventive efficacy of S-methylcysteine (SMC) on rat hepatocarcinogenesis induced by concurrent administration of sodium nitrite (NaNO(2)) and morpholine (Mor) using a medium-term rat liver carcinogenesis bioassay (Ito test). Administration of SMC caused significant reduction in the areas of glutathione S-transferase placental form positive foci along with a significant decrease of hepatocyte 5-bromo-2'-deoxyuridine (BrdU) labeling indices. These results demonstrated potent chemopreventive effects of SMC against hepatocarcinogenesis due to concurrent administration of Mor and NaNO(2). SMC could thus be an effective chemopreventive agent for decreasing the risk of carcinogenicity from environmental precursors of N-nitroso compounds.

Inhibitory effects of S-methylcysteine and cysteine on the promoting potential of sodium phenobarbital on rat liver carcinogenesis

The effects of S-methylcysteine (SMC) and cysteine on the promotion stages of rodent hepatocarcinogenesis in a medium-term bioassay previously developed by Ito were examined. Initiation was induced by a single dose of diethylnitrosamine (DEN), followed by dietary administration of the promoter sodium phenobarbital (NaPB) 2 weeks later, for 6 weeks. Partial hepatectomy was conducted on all the animals at week 3. Inhibitory potential was evaluated by analyzing two markers of carcinogenesis, namely numbers of glutathione S-transferase placental form (GST-P)-positive foci, and proliferating cell nuclear antigen (PCNA). In addition, the level of ornithine decarboxylase (ODC), one of the rate-limiting enzymes of polyamine metabolism induced by promoters, was analyzed. SMC and cysteine induced significant reduction in the areas of GST-P-positive foci. A significant reduction in the PCNA index was observed in the entire liver as well as in GST-P-positive areas. SMC also induced down-regulation of the ODC enzyme activity. Thus, SMC and cysteine were found to inhibit the promotion stage of DEN-induced hepatocarcinogenesis. No cocarcinogenic effects were evident on administration of either of these chemicals with NaPB.

Inhibition by ginseng of 1,2-dimethylhydrazine induction of aberrant crypt foci in the rat colon

The modifying effects of dietary administration of ginseng on the induction and development of 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) were investigated in Fischer 344 (F-344) rats. In Experiment 1, starting at six weeks of age, 65 rats were injected with DMH or saline alone once a week for four weeks. Rats in Groups 1 and 2 were fed diets containing 1% ginseng for five weeks, starting one week before the first dose of DMH. Animals in Groups 3 and 4 received ginseng for eight weeks after DMH treatment; Group 5 served as a carcinogen control group. In Experiment 2, 60 rats were injected with DMH or saline alone four times at one-week intervals. They were also fed diets containing 1% ginseng or the control diet throughout the 30 days of the experiment. In Experiment 1, numbers of foci with at least four crypts were significantly reduced in Group 2 treated with red ginseng during the initiation phase (p < 0.005). In Experiment 2, treatment with red ginseng also resulted in a decrease in the total number of DMH-induced ACF accompanied by a reduction in 5-bromo-2'-deoxyuridine labeling indexes in colonic crypts comprising ACF (p < 0.005 and p < 0.05, respectively). These findings suggest that dietary administration of red ginseng in combination with DMH suppresses colon carcinogenesis of rats, and the inhibition may be associated, in part, with suppression of cell proliferation in the colonic mucosa.

Chemopreventive effects of coumaperine from pepper on the initiation stage of chemical hepatocarcinogenesis in the rat

This study was designed to investigate the chemopreventive action of three natural products, coumaperine, aurapten and an extract from rosemary, against the initiation stage of rat hepato-carcinogenesis. Coumaperine has been isolated from white pepper as a naturally occurring antioxidative agent, but its potential modifying effects on carcinogenesis remain unclear. In experiment 1, a modification of the model developed by Tsuda et al. was applied, with assessment of numbers and areas of induced glutathione S-transferase placental form (GST-P)-positive hepatocellular foci in male F344 rats. Coumaperine, aurapten and the extract from rosemary were administered i.g. at 100 mg / kg / day once daily for 5 days with initiation by diethylnitrosamine (DEN) on day 4 (20 mg / kg, i.p.). Numbers and areas of GST-P-positive foci in each group given test chemicals tended to be decreased as compared to the vehicle control group values, significance being achieved for number with coumaperine. Experiment 2 was planned to investigate the mechanism of the inhibitory effects of coumaperine. Livers at 8 h after initiation by DEN were examined with coumaperine administered at 100 mg / kg / day once daily for 3 days. Proliferating cell nuclear antigen (PCNA)-positive cells tended to be decreased as compared to the vehicle control, but no effects on apoptosis or cytochrome P-450 (CYP) 2E1 expression were apparent. Our results suggest that coumaperine provides protection against initiation of hepatocarcinogenesis, and that this is related to inhibition of cell proliferation.

Possible rare involvement of O6-methylguanine formation as a significant mutational factor in mouse urinary bladder carcinogenesis models

O6-methylguanine is known as one of the major premutagenic lesions in the human and rodent carcinogenesis process. O6-methylguanine-DNA methyltransferase (MGMT), which repairs methylated guanine bases, might prevent the G:C to A:T transition, and transgenic mice carrying this MGMT gene have been reported to be less sensitive to the carcinogenicity of certain alkylating agents. Here we utilized MGMT transgenic mice to assess the significance of O6-methylguanine formation during urinary bladder carcinogenesis. In experiment 1, 100 and 60 ppm N-butyl-N(4-hydroxybutyl)nitrosamine was given for 20 weeks to transgenic and non-transgenic mice in their drinking water. The incidences of urinary bladder carcinomas were not different between transgenic mice and non-transgenic mice. The mutational spectrum of the p53 gene was evaluated by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing. The pattern of p53 mutations of transgenic and non-transgenic mice did not differ, and the frequencies of mutations were 40% and 42%, respectively. G:C to A:T transition mutations were particularly infrequent (1 of 14 mutations, 7%). In experiment 2, N-methyl-N-nitrosourea, which might induce O6-methylguanine in affected alleles, was given once a week, 3 times (total 5 mg) by direct instillation into the urinary bladder through an abdominal incision. No significant neoplastic lesions were detected, although the experiment was limited by severe toxicity of the treatment. p53 immunostaining was done and there was no difference in transgenic and non-transgenic mice. These results suggest that O6-methylguanine formation might not be a significant mutational factor in these mouse urinary bladder carcinogenesis models.

Increased oxidative stress with gene alteration in urinary bladder urothelium after the Chernobyl accident

We have previously shown that bladder urothelium of people living in the cesium-137 ((137)Cs)-contaminated areas of Ukraine demonstrates accumulation of stable p53 and p53 mutational inactivation, preferentially through G:C to A:T transition mutations at CpG dinucleotides, with a codon 245 hot spot. In the present study, we analyzed immuno-histochemically the relationship between oxidative stress markers and over-expression of p53 and H-ras in urinary bladder urothelium from 42 men with benign prostatic hyperplasia. Bladder mapping biopsies were obtained from 15 patients from a highly radiocontaminated area (group I), 14 patients from the less contaminated city of Kiev (group II) and 13 patients as a control group from "clean" (without radiocontamination) areas of Ukraine (group III). Irradiation cystitis with multiple foci of severe dysplasia and carcinoma in situ were observed in 15 of 15 (100%, group I) and 9 of 14 (64%, group II) cases, with 4 small transitional-cell carcinomas incidentally detected in groups I and II. Markedly elevated levels of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2) and 8-hydroxy-2;-deoxyguanosine (8-OHdG) were noted in these bladder urothelial lesions from groups I and II, accompanied by strong over-expression of p53 and less H-ras expression. These findings support the hypothesis that iNOS, COX-2 and 8-OHdG in bladder urothelium are induced by long-term exposure to low-dose radiation with a close relationship to p53 over-expression that could predispose to bladder carcinogenesis.

Promotion of skin carcinogenesis by dimethylarsinic acid in keratin (K6)/ODC transgenic mice

Dimethylarsinic acid (DMA) is a major metabolite of inorganic arsenicals in mammals, and arsenic exposure is associated with tumor development in a wide variety of human tissues, particularly the skin. Transgenic mice with ornithine decarboxylase (ODC) targeted to hair follicle keratinocytes are much more sensitive than littermate controls to carcinogens. In this study we investigated the promoting effect of DMA on skin carcinogenesis in such K6 / ODC transgenic mice. The back skin of female C57BL / 6J K6 / ODC transgenic mice, 10 to 14 weeks old, was initiated with topical application of 7, 12-dimethylbenz[alpha]anthracene (DMBA) at a dose of 50 microg or acetone alone on day 1 of the experiment, followed by treatment with 3.6 mg of DMA, 5 microg of 12-O-tetradecanoylphorbol-13-acetate (TPA) or neutral vehicle (control) twice a week for 18 weeks. Mice were killed 1 week after the end of the treatment. Induction of skin tumors was significantly accelerated in the DMA-treated group, as well as in the TPA-treated group, indicating that DMA has a promoting effect on skin tumorigenesis in K6 / ODC transgenic mice.

Chemopreventive effects of bovine lactoferrin on N-butyl-N-(4-hydroxybutyl)nitrosamine-induced rat bladder carcinogenesis

Chemopreventive effects of bovine lactoferrin (bLF), which is found at high concentrations in colostrum, on rat bladder carcinogenesis were investigated using a rat bladder medium-term bioassay. In experiment 1, a total of 80 F344 male rats, 6 weeks old, were divided into 5 groups. Groups 1 and 2 were treated with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in the drinking water for 8 weeks and after a 1-week interval, received dietary supplementation with 2% and 0.2% bLF, respectively. Group 3 received 0.05% BBN for 8 weeks and then no treatment. Group 4 was administered 2% bLF alone from week 9, without prior carcinogen exposure. Group 5 was maintained without any treatment throughout the experiment. All rats were killed at the end of week 36. Group 1 demonstrated a significantly decreased multiplicity of the bladder tumors (carcinomas and papillomas) as compared with group 3. Maximum cut surface areas of bladder tumors were also significantly decreased in groups 1 and 2 compared with group 3. No bladder tumors were observed in groups 4 or 5. In experiment 2, a total of 60 rats were divided into two groups (30 rats each); both were treated with 0.05% BBN for 4 weeks and after a 1-week interval, one received 2% bLF (group 1) and the other, basal diet (group 2) for 4 weeks. Group 1 demonstrated a tendency for decrease of the 5-bromo-2'-deoxyuridine (BrdU) labeling index. bLF was detected in the urine of rats fed bLF by ELISA as well as western blot analysis. The findings indicate that 2% bLF can inhibit BBN-induced rat bladder carcinogenesis, and that this may be due to bLF in the urine.

Significant overexpression of metallothionein and cyclin D1 and apoptosis in the early process of rat urinary bladder carcinogenesis induced by treatment with N-butyl-N-(4-hydroxybutyl)nitrosamine or sodium L-ascorbate

Effects of a genotoxic bladder carcinogen, N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) and a non-genotoxic bladder promoter, sodium L-ascorbate (Na-AsA), on protein expression, cell proliferation and apoptosis of the bladder epithelium with or without the influence of testicular castration were investigated. Male F344 rats were divided into six groups (groups 1-6). BBN was given with 0.05% drinking water to groups 1 and 4 for 8 weeks, groups 2 and 5 received diet with 5% Na-AsA. Then the animals were treated without any chemicals. Groups 3 and 6 were non-treated controls. Testicular castration was carried out 2 weeks before commencement of chemical treatment on groups 4-6. The total observation period was 18 weeks. Overexpression of cyclin D1 was induced by BBN but not Na-AsA and the degree of overexpression was higher in the order simple hyperplasia, papillary or nodular hyperplasia, papilloma and carcinoma. Metallothionein (MT) was also overexpressed in bladder epithelium treated with BBN but not Na-AsA, but was decreased in papillomas and never found in a carcinoma. Cyclin D1-positive cells were essentially MT-negative. Therefore, it is speculated that MT protects genes from insult by genotoxic carcinogens and its lack is associated with tumor development. Apoptotic cell death occurred during treatment with BBN and Na-AsA and after their withdrawal. Chromatin condensation of many G0/G(1) cells was particularly marked on flow cytometry analysis 1 week after cessation of treatment, this being considered as an early apoptotic change. Although testicular castration had no influence on the above events, it resulted in decreased tumor formation as compared with the case of similarly treated intact animals. Our data demonstrate that overexpression of MT and cyclin D1 is specific for treatment with a genotoxic carcinogen, and suggest that MT overexpression may play an important suppressive role in the early stages of rat urinary bladder carcinogenesis.

Inhibitory effects of 1,3-diaminopropane, an ornithine decarboxylase inhibitor, on rat two-stage urinary bladder carcinogenesis initiated by N-butyl-N-(4-hydroxybutyl)nitrosamine

Overexpression of ornithine decarboxylase (ODC) has been shown to be characteristic of tumor development and progression in humans and experimental animals. Therefore, we have examined the effects of 1, 3-diaminopropane dihydrochloride (DAP), a potent inhibitor of ODC, on rat two-stage urinary bladder carcinogenesis initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). In experiment 1 (36 weeks), 6-week-old F344 male rats were administered 0.05% BBN in drinking water for 4 weeks and then divided into four groups. Animals of groups 1 and 2 received basal diet and drinking water supplemented with or without DAP (2 g/l). Groups 3 and 4 were given diet containing 5% sodium L-ascorbate (NaAsA), a typical urinary bladder tumor promoter, and drinking water with or without DAP. Administration of DAP to group 1 significantly reduced tumor size, multiplicity and incidence, particularly of papillomas, when compared with group 2 values. DAP together with NaAsA (group 3) also decreased tumor size relative to the group 4 case. To determine the effects of DAP on the early stages of bladder carcinogenesis and its mechanisms, a similar protocol was conducted (experiment 2) with death after 20 weeks. DAP treatment caused complete inhibition (0% incidence) of papillary and/or nodular hyperplasia in group 1 but was without influence in group 3, as compared with the respective controls. Moreover, the ODC activity, bromodeoxyuridine labeling indices and mRNA expression levels of cyclin D1 in the urinary bladder mucosa, determined by northern blotting, were markedly lower in group 1 than in group 2, but values were comparable for both groups administered NaAsA. Assessment of mRNA expression levels of the angiogenic vascular endothelial growth factor suggested no involvement in the inhibitory effects of DAP on urinary bladder carcinogenesis. The results indicate that inhibition of ODC could reduce urinary bladder carcinogenesis in rats, particularly in the early stages, through antiproliferative mechanisms.

Chemopreventive effect of 24R,25-dihydroxyvitamin D(3) in N, N'-dimethylhydrazine-induced rat colon carcinogenesis

In this study we investigated the effects of 24R,25-dihydroxyvitamin D(3) [24R,25(OH)(2)D(3)] on N,N'-dimethylhydrazine (DMH)-induced rat colon carcinogenesis. For experiments 1 and 2, 50 F344 male, 6-week-old rats were divided into five groups in each experiment. Animals were given s.c. injections of DMH once a week for 4 weeks. Those in groups 1-5 were given 24R,25(OH)(2)D(3) in the diet (10, 5, 2.5, 1.25 or 0 p.p.m., respectively) during the post-initiation stage in experiment 1 and during the initiation stage in experiment 2. At termination, the numbers of aberrant crypt foci (ACF) in the rat colonic mucosa were decreased dose-dependently in rats treated with 24R,25(OH)(2)D(3) during the post-initiation stage, but not in the initiation stage. For experiment 3, 15 male, 9-week-old rats were divided into three groups and given 24R,25(OH)(2)D(3) in the diet (10, 5 or 0 p.p.m.). Animals were injected with 5-bromo-2'-deoxyuridine (BrdU) i.p. 1 h before death to examine DNA synthesis in the colon mucosa. BrdU labeling indices were decreased dose-dependently in colonic crypts of rats treated with 24R, 25(OH)(2)D(3). In experiment 4, using the multicarcinogenic protocol we could analyze our data with respect to not only one separate organ, but at the organism level. Sixty-eight male, 6-week-old rats were treated with DMH, N-methylnitrosourea, 2, 2'-dihydroxy-di-n-propylnitrosamine, diethylnitrosamine and N-butyl-N-(4-hydroxybutyl)nitrosamine in weeks 1-4 and were then given 24R,25(OH)(2)D(3) in the diet (5, 1 or 0 p.p.m.) throughout weeks 5-30. Examination of the development of tumors and preneoplastic lesions in various organs revealed that 24R, 25(OH)(2)D(3) inhibited colonic tumor development significantly but exerted no effects on tumor induction in other organs. In conclusion, these results strongly indicate that 24R,25(OH)(2)D(3) inhibits colon carcinogenesis specifically, without any enhancement of carcinogenesis in other organs, when administered in the post-initiation phase.

p53 status in multiple human urothelial cancers: assessment for clonality by the yeast p53 functional assay in combination with p53 immunohistochemistry

Multifocal synchronous or metachronous tumor development is a common observation in human urothelial cancer cases. However, the underlying mechanism has remained obscure. We have employed a new tool to investigate the p53 gene status, the yeast p53 functional assay, in combination with immunohistochemistry in a total of 50 tumor samples from 32 cases with urothelial cancers, including 8 with multiple synchronous tumor development and 2 demonstrating metachronous tumors. p53 mutations were found in 13 cases (9 with missense mutations, 3 with deletion, 1 with splicing mutation) by the yeast p53 functional assay. p53 protein overexpression was seen in all 9 cases with missense mutations, but in only one of the 4 cases with nonsense mutations. Two tumors without p53 mutation also showed positive p53 immunoreactivity. Overall, p53 abnormalities including mutations and/or protein overexpression were found in 15 (47%) cases. p53 abnormalities were significantly more frequent in non-papillary and in high grade tumors. Loss of the wild type allele in addition to a p53 mutation was suggested in 8 of the 15 (53%) cases. All 4 cases with mutations in multiple synchronous tumors had identical p53 mutations in the separate urothelial cancers, strongly suggestive of monoclonality. The one case with multiple metachronous tumors, in contrast, was characterized by variation in the p53 status, indicative of different clonal origins. In conclusion, combined assessment for p53 status as used here (yeast p53 functional assay plus immunohistochemistry) may provide insights into the molecular mechanisms of urothelial carcinogenesis.

Organ-specific, carcinogen-induced increases in cell proliferation in p53-deficient mice

Transgenic mice with germ-line p53 alleles disrupted by gene targeting are sensitive to the development of some spontaneous tumors and have provided researchers with much information with respect to cancer. In the present study, to cast light on the organ specificity of chemically induced carcinogenesis, we evaluated carcinogen-induced cell proliferation in target organs in heterozygote p53 knockout mice (p53-deficient mice). Groups of 9- or 10-week-old wild-type(+/+) and p53-deficient mice were respectively treated with one of the following carcinogens for 4 weeks: N-butyl-N-(4-hydroxybutyl)nitrosamine (0.0075% in drinking water); dimethylnitrosamine (0.001% in drinking water); dihydroxy-di-N-propylnitrosamine (0.1% in drinking water); 1,2-dimethylhydrazine (10 mg/kg body weight s.c. injection once a week); 4-nitroquinoline 1-oxide (4-NQO, 10 mg/kg b.w. s.c. injection once a week); or 7,12-dimethylbenz(a)anthracene (25 microg/kg body weight dermal application once a week). Cell proliferation was evaluated by measuring the 5-bromo-2'-deoxyuridine labeling indices in each target organ. The p53 and p21 statuses were evaluated by comparing the expressions of p53 protein, p21waf1/cip1 mRNA, and p21waf1/cip1 protein between the mice. 5-Bromo-2'-deoxyuridine labeling indices of the urinary bladder and the skin were significantly increased in p53-deficient mice as compared with the wild-type(+/+) mice. In the all organs examined, carcinogen-induced p21waf1/cip1 mRNA overexpression was detected with levels obviously lower in the p53-deficient animals. These data suggest that p53-deficient mice have an organ-specific increased sensitivity to the induction of cell proliferation in the urinary bladder and the skin. These are the same organs for which sensitivity to carcinogenesis has been reported. Because a decrease of p21waf1/cip1 protein overexpression was also observed in the organs in which cell proliferation did not appreciably differ from the level in wild-type(+/+) mice, this decrease might have no effect on sensitivity to cell proliferation and carcinogenesis. Alternatively, it might play an important role in the cell cycle regulation of only the sensitive organs.

Low-dose-dependent carcinogenic potential of 2-amino-3-methylimidazo[4,5-f]quinoline in the immunodeficient (SCID) mouse colon

The carcinogenic potential of 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), one of the most potent mutagenic heterocyclic aromatic amines in food, for the colon was assessed in mice with severe combined immunodeficiency (SCID). In Experiment I, 60 male animals, 7-8 weeks old, were administered 300, 100, or 0 ppm IQ in the diet for 20 weeks. The incidence of aberrant crypt foci (ACF), preneoplastic lesions, was 100% in the two IQ-administered groups, whereas no ACF were found in the controls. Larger lesions, at least four aberrant crypts per focus, were noted in the colons of both treated groups. Most ACF were located in the proximal colon, and the bromodeoxyuridine-labeling indexes were elevated in a dose-dependent manner, especially in this region. In Experiment II, IQ was administered in the diet at 50, 10, 2, or 0 ppm to 60 female and male 7- to 8-week-old SCID mice for 30 and 23 weeks, respectively. The incidence of ACF was dose dependent in both sexes: 100%, 100%, and 63% in the females administered 50, 10, and 2 ppm, respectively, and 100%, 83%, and 38%, respectively, in the males. Lesions of at least four aberrant crypts per focus were again evident with the 50-ppm dose. The long-term or higher dose administration of IQ in the diet might thus be applied to elucidate colon carcinogenesis in the SCID mouse.

Concentration dependent promoting effects of sodium L-ascorbate with the same total dose in a rat two-stage urinary bladder carcinogenesis

Sodium L-ascorbate (Na-AsA) has been demonstrated to be a strong promoter of rat urinary bladder tumor development initiated by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). In the present study, we investigated variation in its promoting activity when the same total dose was given with different concentrations and exposure times. After 4 weeks administration of 0.05% BBN, group 1 served as a control without any post-initiation treatment. The rats in groups 2-4 received 1.25% Na-AsA diet for 36 weeks, 2.5% Na-AsA for 18 weeks and 5% Na-AsA for 8 weeks, respectively. Tumor number (papillomas and carcinomas) was greatest in group 3, and area in group 4 (P < 0.05). However, no enhancement was noted in group 2, although preneoplastic lesions were significantly increased. These results suggest that with the same total administration dose, high concentration of Na-AsA has the strongest promoting effects on tumor development in urinary bladder carcinogenesis.

Reduced expression of the CDK inhibitor p27(KIP1) in rat two-stage bladder carcinogenesis and its association with expression profiles of p21(WAF1/Cip1) and p53

The cyclin-dependent kinase (CDK) inhibitor p27(KIP1) exerts its growth suppressive effects by targeting the cyclin-CDK complexes. Reduced protein levels of p27(KIP1) have been reported in numerous human cancers and this has been attributed to increased degradation. However, few reports have addressed the significance of p27(KIP1) expression in chemical carcinogenesis of rodents. In a rat two-stage urinary bladder carcinogenesis model, with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) initiation followed by promotion with sodium L-ascorbate (Na-AsA), we evaluated the expression of p27(KIP1) protein using immunohistochemistry during various stages of urinary bladder carcinogenesis. In addition, we evaluated the mRNA expression profiles for p27(KIP1), p21(WAF1/Cip1) and p53 in tumors. Fisher 344 rats were initiated with 0.05% BBN in the drinking water for 4 weeks and then administered 5% Na-AsA in the diet. Immunohistochemical examination revealed p27(KIP1) protein to be constitutively expressed in normal urothelium, simple hyperplasia and in most papillary and nodular (PN) hyperplasias and small papillomas, but diminished or absent in large papillomas and in transitional cell carcinomas. An inverse correlation between expression of p27(KIP1) and cell proliferation was generally observed. Quantitation of mRNA by multiplex reverse transcription-PCR showed a significant downregulaton of p27(KIP1), p21(WAF1/Cip1) and p53 mRNA in tumors. More than 50% reduction in p27(KIP1) mRNA expression was observed in 42 and 47% of tumors at weeks 18 and 24, respectively; similar reduction in p21(WAF1/Cip1) mRNA expression was observed in 58 and 73% of tumors at weeks 18 and 24, and in p53 mRNA expression in 50 and 73% of tumors at weeks 18 and 24, respectively. None of the 25 tumors we examined by PCR-single-strand conformational polymorphism analysis had p53 mutations. These data imply that abnormal down-regulation of p27(KIP1), p21(WAF1/Cip1) and/or p53 in tumor cells may contribute to the malignant progression of tumors during rat two-stage bladder carcinogenesis.

Urinary bladder carcinogenicity of dimethylarsinic acid in male F344 rats

The present study was conducted to determine the carcinogenicity of dimethylarsinic acid (DMA) administered to male F344 rats in a 2 year bioassay. A total of 144 rats (10 weeks old at the start) were divided into four groups of 36 rats each. Groups 1-4 received DMA (purity 100%) at concentrations of 200, 50, 12.5 and 0 p.p.m. in the drinking water, respectively, for 104 weeks. From weeks 97 to 104, urinary bladder tumors were observed in 12 of 31, eight of 31 and none of 33 in groups 1-3, respectively. No bladder tumors were observed in group 4. The present study demonstrated that long-term p. o. administration of DMA induced urinary bladder carcinomas in male F344 rats. Therefore, the results indicate that DMA is carcinogenic for the rat urinary bladder, which may be related to the human carcinogenicity of arsenicals.

Thallium and FDG uptake by atelectasis with bronchogenic carcinoma

We report a case of bronchogenic carcinoma with atelectasis studied by T1-SPECT and FDG-PET. In the carcinoma, abnormally high uptake of T1 and FDG were detected, but in the region of atelectasis, an abnormally high uptake of T1 with a relatively low uptake of FDG were observed. On quantitative analyses, the T1 retention indexes of the tumor and atelectasis were 29.7 and 42.0. The mean SUVs of FDG of the tumor and the atelectasis were 8.92 and 1.28. T1-SPECT could not distinguish the atelectasis from the carcinoma. FDG-PET was superior to T1-SPECT in this case in detecting malignancy and distinguishing it from atelectasis.

Two cases of chronic tonsillitis studied by FDG-PET

We report two cases of chronic tonsillitis studied by FDG-PET. Symmetrical high FDG uptake by the tonsils was observed in both cases. On histopathologic examination of the resected tonsils, follicular hyperplasia was observed with proliferation of lymphocytes in the germinal centers. Increased glucose metabolism in active inflammation involving lymphocyte proliferation was thought to be a cause of high FDG uptake by tonsils in chronic tonsillitis.

Loss of heterozygosity in (LewisxF344)F1 rat urinary bladder tumors induced with N-butyl-N-(4-hydroxybutyl)nitrosamine followed by dimethylarsinic acid or sodium L-ascorbate

Dimethylarsinic acid (DMA), a main metabolite of arsenicals which are carcinogenic in man, exerts tumor-promoting activity on rat urinary bladder carcinogenesis initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). Sodium L-ascorbate (Na-AsA) is also a strong tumor promoter in this animal model. In this study, we used (LewisxF344)F, rats to compare molecular alterations in urinary bladder tumors caused by BBN followed by DMA or Na-AsA. Male, 6-week-old rats were given 0.05% BBN in their drinking water for 4 weeks, and then the rats in group 1 were maintained with no further treatment for 40 weeks. The animals of groups 2 and 3 were administered 0.01% DMA in their drinking water (group 2) or 5% Na-AsA in the powder diet (group 3) after the BBN treatment. Group 4 rats were given 0.05% BBN continuously for 36 weeks. At weeks 12, 20, 36 and 44, subgroups of rats were killed. Histopathological examination revealed promoting activity for DMA and, to a greater extent, Na-AsA on urinary bladder carcinogenesis. Loss of heterozygosity (LOH), detected with the polymerase chain reaction using 36 microsatellite markers, was found to be present in 2 of 9 (22%) urinary bladder tumors after treatment with DMA and 3 of 22 (14%) induced by continuous administration with BBN. No LOH was, however, detected in urinary bladder tumors after treatment with Na-AsA. The results thus suggest that the mechanisms of action of these two promoters, DMA and Na-AsA, may differ in rat urinary bladder carcinogenesis.

Specific p53 gene mutations in urinary bladder epithelium after the Chernobyl accident

After the Chernobyl accident, the incidence of urinary bladder cancers in the Ukraine population increased gradually from 26.2 to 36.1 per 100,000 between 1986 and 1996. Urinary bladder epithelium biopsied from 45 male patients with benign prostatic hyperplasia living in radiocontaminated areas of Ukraine demonstrated frequent severe urothelial dysplasia, carcinoma in situ, and a single invasive transitional cell carcinoma, combined with irradiation cystitis in 42 cases (93%). No neoplastic changes (carcinoma in situ or transitional cell carcinoma) were found in 10 patients from clean areas (areas without radiocontamination). DNA was extracted from the altered urothelium of selected paraffin-embedded specimens that showed obviously abnormal histology (3 cases) or intense p53 immunoreactivity (15 cases), and mutational analysis of exons 5-8 of the p53 gene was performed by PCR-single-strand conformational polymorphism analysis followed by DNA sequencing. Nine of 17 patients (53%) had one or more mutations in the altered urothelium. Urine sediment samples were also collected from the patients at 4-27 months after biopsy and analyzed by PCR-single-strand conformational polymorphism analysis or yeast functional assay, and identical or additional p53 mutations were found in four of five cases. Interestingly, a relative hot spot at codon 245 was found in five of nine (56%) cases with mutations, and 11 of the 13 mutations determined (73%) were G:C to A:T transitions at CpG dinucleotides, reported to be relatively infrequent (approximately 18%) in human urinary bladder cancers. Therefore, the frequent and specific p53 mutations found in these male patients may alert us to a future elevated occurrence of urinary bladder cancers in the radiocontaminated areas.

Elevation of urinary enzyme levels in rat bladder carcinogenesis

Urinary enzyme levels were investigated in rats administered different promoters in their diet for 32 weeks after being initiated by treatment with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine in their drinking water for 4 weeks. All groups were composed of 10 rats each. Group 1: females treated with 3% uracil (100% carcinoma incidence). Group 2: control females kept on basal diet only (0% carcinoma incidence). Group 3: males treated with 5% sodium L-ascorbate (100% carcinoma incidence). Group 4: control males (0% carcinoma incidence). Urine was collected at the end of weeks 12, 24 and 36 and tested for lactate dehydrogenase (LDH), alkaline phosphatase, N-acetyl-beta-D-glucosaminase and aspartate aminotransferase activity. To facilitate comparison, data were related to the corresponding excreted creatinine levels. All measurements were made using a centrifugal automatic analyzer. The urine of rats with cancer lesions (groups 1 and 3) showed significant elevation in all enzyme activities at weeks 24 and/or 36 except for LDH in females (group 1). The M/H ratio of the LDH isozymes was reversed (1.10 +/- 0.10) in the tested rats with carcinomas at week 36. This study thus provides evidence of a correlation between high urinary enzyme levels and cancer development in the rat bladder. Measurement of the tested enzymes might thus provide a method to detect malignant changes in bladder epithelium by direct urine analysis.

Molecular cytogenetic identification of cyclin D1 gene amplification in a renal pelvic tumor attributed to phenacetin abuse

Despite extensive epidemiologic evidence of phenacetin abuse as a risk factor for renal pelvic carcinomas, genetic alterations in the resultant tumors remain largely unclear. In this report, a phenacetin-associated renal pelvic carcinoma (histologically a transitional-cell carcinoma) from an 80-year-old female patient was evaluated by molecular cytogenetic methods. Fluorescence in situ hybridization was used to identify chromosome gains or losses for the cyclin D1, p53, Rb and c-myc genes and the ploidy of their respective chromosomes. Cyclin D1 gene amplification, but normal copy numbers of p53, Rb and c-myc, and normal ploidy of chromosomes 8, 11, 13 and 17 were observed. Expression of cyclin D1 protein was confirmed by immunohistochemistry. In the absence of p53, Rb or c-myc abnormalities, the results suggested that cyclin D1 gene amplification and its protein overexpression may be involved in the genesis of renal pelvic carcinomas associated with phenacetin abuse.

Inhibition of liver glutathione S-transferase placental form-positive foci development in the rat hepatocarcinogenesis by Porphyra tenera (Asakusa-nori)

The effects of Asakusa-nori, Porphyra tenera (PT), a popular edible seaweed in Japan, on the development of putative preneoplastic lesions, glutathione S-transferase placental form (GST-P)-positive foci, in the male F344 rat liver were examined using a medium-term bioassay system. PT significantly decreased both the number and area of GST-P-positive foci in rat livers initiated with diethylnitrosamine (DEN). To investigate possible mechanisms of inhibition, effects of PT on 5-bromo-2'-deoxyuridine (BrdU) labeling in GST-P-positive foci and the surrounding area of hepatocytes were studied. The ratio of the GST-P-positive foci to surrounding tissue labeling indices was decreased in the PT-treated group as compared with the DEN alone group. Ornithine decarboxylase activity in the liver was slightly increased and spermidine/spermine N'-acetyltransferase activity was slightly decreased in the PT-treated animals. These results suggest that PT possesses chemopreventive effects against DEN-induced hepatocarcinogenesis.

An autopsy report of graft-versus-host disease (GVHD) following blood transfusion

A case of graft-versus-host disease (GVHD) associated with blood transfusion in a 71-year-old man is reported. The patient received transfusions (irradiation red cells M.A.P 14 units, fresh frozen plasma 11 units) and developed features of GVHD including fever, a skin rash, diarrhea, liver dysfunction, hypoplastic bone marrow, and pancytopenia. He died on day 32 posttransfusion. Pathologically, lymphocyte infiltration of skin and liver lesions, degeneration of small bile ducts, crypt cell necrosis in the gastrointestinal tract, and bone marrow hypoplasia were observed. Immunohistochemically, infiltrating lymphocytes were CD8+ T type, the result suggesting that they role a part in posttransfusion GVHD.

Dose-dependent induction of aberrant crypt foci in the colons but no neoplastic lesions in the livers of heterozygous p53-deficient mice treated with low dose 2-amino-3-methylimidazo [4,5-f]quinoline

2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) is a food derived heterocyclic amine which induces aberrant crypt foci (ACF) and tumors in the livers in mice. However, most previous studies of carcinogenicity were carried out with high dose treatments, so the practical risk associated with the low dose exposure is unclear. We, therefore, assessed whether low dose IQ causes ACF formation in the colons of mice constitutively hemizygous for functional p53. Simultaneously, we screened for development of preneoplastic foci in the liver. A total of 60 heterozygous p53-deficient mice as well as 60 wild-type mice were divided into five groups and administered IQ in the diet at concentrations of 50, 10, 2, 0.4 and 0 ppm until the end of the experiment. ACF were detected in the 50, 10 and 2 ppm-treated groups and the numbers of those comprising one aberrant crypt (AC) in p53-deficient mice treated with 10 or 2 ppm were significantly increased, compared to counterpart wild-type values. A dose-dependent increase of ACF was also observed in transgenic mice groups but no large ACF developed. In spite of extensive examination, no preneoplastic foci could be detected in either transgenic or wild-type mice. The results suggested that germline p53 deficiency may slightly enhance the development of ACF in colons but not in the liver. The fact that no ACF were detected in the lowest, 0.4 ppm, treated groups may imply a practical non-effective level of IQ for tumor induction.

LOH and mutational analysis of p53 alleles in mouse urinary bladder carcinomas induced by N-butyl-N-(4-hydroxybutyl) nitrosamine

In human urinary bladder carcinogenesis, alterations in the p53 tumor suppressor gene are common events. We have previously reported that they are also frequent in invasive urinary bladder carcinomas induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in NON/Shi mice. To further investigate the significance of the p53 gene status for mouse urinary bladder carcinogenesis, we examined both allele loss and mutational alterations in urinary bladder cancers of (NON/Shi x C3H/He/Shi) F1 hybrid mice exposed to the carcinogen for 12 weeks and then maintained for a further 9 weeks without treatment. An intragenic silent polymorphism within exon 7 of the p53 gene between NON/Shi and C3H/He/Shi mice allows assessment of allele loss of the p53 gene and determination of the parental origin of mutated and/or lost alleles. A tissue microdissection method was employed to obtain carcinoma samples without excessive contamination with normal tissue. Allele losses were detected in one of 14 tumors (7.1%) and nine mutations in eight of 14 (57%) tumors were found in exons 5-8 by polymerase chain reaction-single strand conformation polymorphism followed by DNA direct sequencing analysis. All mutations involved one base substitution with an amino acid change, although the types of base substitution were random. In conclusion, the high incidence of p53 alterations suggests a significant role in the genesis of invasive urinary bladder tumors in BBN-treated mice.

Urinary bladder lesions after the Chernobyl accident: immunohistochemical assessment of p53, proliferating cell nuclear antigen, cyclin D1 and p21WAF1/Cip1

During the 11-year period subsequent to the Chernobyl accident, the incidence of urinary bladder cancer in Ukraine has increased from 26.2 to 36.1 per 100,000 population. Cesium-137 (137Cs) accounts for 80-90% of the incorporated radioactivity in this population, which has been exposed to long-term, low-dose ionizing radiation, and 80% of the more labile pool of cesium is excreted via the urine. The present study was performed to evaluate the histopathological features and the immunohistochemical status of p53, p21WAF1/Cip1, cyclin D1 and PCNA (proliferating cell nuclear antigen) in urinary bladder mucosa of 55 males (49-92 years old) with benign prostatic hyperplasia who underwent surgery in Kiev, Ukraine, in 1995 and 1996. Group I (28 patients) inhabiting radiocontaminated areas of the country, group II (17 patients) from Kiev city with less radiocontamination and a control group III (10 patients) living in so-called "clean" areas of Ukraine were compared. In groups I and II, an increase in multiple areas of moderate or severe dysplasia or carcinoma in situ was seen in 42 (93%) of 45 cases. In addition, two small transitional cell carcinomas were found in one patient in each of groups I and II. Nuclear accumulation of p53, PCNA, cyclin D1, and to a lesser extent p21WAF1/Cip1, was significantly increased in both groups I and II as compared with the control group III, indicating possible transformation events or enhancement of repair activities, that may precede the defect in the regulatory pathway itself, at least in the G1 phase of the cell cycle. Our results suggest that early malignant transformation is taking place in the bladder urothelium of people in the radiocontaminated areas of Ukraine and that this could possibly lead sometime in the future to an increased incidence of urinary bladder cancer.

Lack of inhibitory effects of the Ju-myo protein on development of glutathione S-transferase placental form-positive foci in the male F344 rat liver

The effects of the 77 kDa Ju-myo protein, isolated from Drosophila melanogaster, on the development of glutathione S-transferase placental form (GST-P) positive foci in the male F344 rat liver were evaluated using a medium-term bioassay system. No modifying potential was evident in terms of the numbers or areas of GST-P positive foci. Ju-myo protein did not exert any influence on cell proliferation, as reflected by ornithine decarboxylase (ODC) or spermidine/spermine N1-acetyltransferase (SAT) activity and BrdU labeling. These results demonstrated that Ju-myo protein is unlikely to have inhibitory or promoting effects on rat liver carcinogenesis.

Enhancement of urinary bladder carcinogenesis in nullizygous p53-deficient mice by N-butyl-N-(4-hydroxybutyl)nitrosamine

We recently reported p53 mutations to be frequent in mouse invasive urinary bladder carcinomas, with and without metastasis. However, the role of p53 dysfunctions during carcinogenesis remains unclear. In the present study, heterozygous and nullizygous p53-deficient mice and their littermates were treated with the urinary bladder carcinogen, N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN), at a concentration of 0.01% in the drinking water throughout the experiment. This markedly accelerated urinary bladder carcinogenesis but not development of other tumors in the nullizygous p53-deficient mice. Thus the appearance of neoplastic urothelial lesions in nullizygotes (at day 60 of the experiment) was earlier than in wild-type mice and heterozygotes (at day 125). Moreover, malignant vascular tumors (hemangiosarcomas (HS)) were found in all four nullizygotes killed later than day 108. Mutational inactivation of the wild-type allele was not apparent in either the single transitional cell carcinoma observed in a wild-type mouse and a hemangiosarcoma in a heterozygote. Overall, it can be concluded that the number of normal p53 alleles is a significant determining factor in the susceptibility of urothelial cells to carcinogens. The role of the p53 defect in mouse urinary bladder carcinogenesis may thus be to diminish the threshold for occurrence of additional genetic alterations.