Expression of vascular endothelial growth factor in N-butyl-N-(4-hydroxybutyl)nitrosamine-induced rat bladder carcinogenesis. (1/87)

Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are proteins implicated in tumor-associated microvascular angiogenesis. Expressions of VEGF and bFGF in various stages of chemical-induced rat bladder carcinogenesis were immunohistochemically investigated. Thirty-two male 6-week-old Wistar rats were given drinking water containing 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 20 weeks. VEGF and bFGF were not detected in the normal bladder epithelium. In simple hyperplasia, intensive expression of VEGF was observed in a few epithelial cells, and the expression of epithelial VEGF became more pronounced in papillary or nodular (PN) hyperplasia and papilloma. In carcinoma, heterogeneous expression of VEGF was observed in focal tumor cells, intensely expressed in the invading tumor cells. Ultrastructurally, carcinoma cells showed VEGF immunoreactivity in the cytoplasmic matrix and some rough endoplasmic reticulum, and VEGF-positive and -negative carcinoma cells were also clearly defined. High levels of VEGF mRNA were observed in the carcinoma. However, bFGF was not detected in the epithelium throughout the carcinogenesis. Increased microvessel counts appeared at simple hyperplasia and became more pronounced in PN hyperplasia, papilloma, and carcinoma (F-test; P < 0.05). In the carcinoma, the microvessel counts of the VEGF-expressing tumor areas were significantly higher than that of the non-VEGF-expressing tumor areas (U-test; P < 0.05). The present study suggests that upregulation of epithelial VEGF may begin at a quite early stage in BBN-induced rat bladder carcinogenesis, but bFGF may not be involved.  (+info)

LOH and mutational analysis of p53 alleles in mouse urinary bladder carcinomas induced by N-butyl-N-(4-hydroxybutyl) nitrosamine. (2/87)

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.  (+info)

Elevation of urinary enzyme levels in rat bladder carcinogenesis. (3/87)

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.  (+info)

Metallothionein modulates the carcinogenicity of N-butyl-N-(4-hydroxybutyl)nitrosamine in mice. (4/87)

We examined the carcinogenicity of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in transgenic mice deficient in the metallothionein (MT) I and II genes and in control (129/Sv) mice. Both strains of mice were given BBN for 8 weeks with or without Zn treatment. All mice were killed at 12 weeks after the cessation of BBN administration. BBN induced bladder tumors in 75% of MT null mice and in 43% of 129/Sv mice. The average number of bladder tumors per mouse was significantly higher in MT null mice (1. 18 +/- 0.27) than in 129/Sv mice (0.43 +/- 0.20). Zn treatment suppressed the carcinogenicity of BBN in 129/Sv mice but not in MT null mice. Histopathological examination of the tumors revealed that the malignant potential of bladder tumors in 129/Sv mice was greater than that in MT null mice. These results indicate that MT is an important modulator of carcinogenicity of BBN in the bladder of mice.  (+info)

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. (5/87)

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.  (+info)

Comparison of uroplakin expression during urothelial carcinogenesis induced by N-butyl-N-(4-hydroxybutyl)nitrosamine in rats and mice. (6/87)

The expression of uroplakins, the tissue-specific and differentiation-dependent membrane proteins of the urothelium, was analyzed immunohistochemically in N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-treated rats and mice during bladder carcinogenesis. Male Fischer 344 rats were treated with 0.05% BBN in the drinking water for 10 wk and were euthanatized at week 20 of the experiment. BBN was administered to male B6D2F, mice; it was either provided at a rate of 0.05% in the drinking water (for 26 wk) or 5 mg BBN was administered by intragastric gavage twice weekly for 10 wk, followed by 20 wk without treatment. In rats, BBN-induced, noninvasive, low-grade, papillary, transitional cell carcinoma (TCC) showed decreased uroplakin-staining of cells lining the lumen but showed increased expression in some nonluminal cells. In mice, nonpapillary, high-grade dysplasia, carcinoma in situ, and invasive carcinoma were induced. There was a marked decrease in the number of uroplakin-positive cells lining the lumen and in nonluminal cells. This occurred in normal-appearing urothelium in BBN-treated mice and in dysplasic urothelium, in carcinoma in situ, and in invasive TCC. The percentage of uroplakin-positive nonluminal cells was higher in control mice than in rats, but it was lower in the mouse than in the rat after BBN treatment. Uroplakin expression was disorderly and focal in BBN-treated urothelium in both species. These results indicate that BBN treatment changed the expression of uroplakins during bladder carcinogenesis, with differences in rats and mice being related to degree of tumor differentiation.  (+info)

Increased expression of cyclooxygenase-2 protein in rat urinary bladder tumors induced by N-butyl-N-(4-hydroxybutyl) nitrosamine. (7/87)

The anti-inflammatory drugs, aspirin and piroxicam, are known to possess chemopreventive potential against rat superficial urinary bladder carcinogenesis induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). Recently, we found similar inhibitory effects with a selective cyclooxygenase (COX)-2 inhibitor, nimesulide. In order to clarify the inhibitory mechanisms, we have further studied the expression of COX-2 protein in urinary bladder tumors induced by BBN in Fischer 344 male rats. For comparison, papillomatosis caused by uracil-induced urolithiasis, and normal epithelial cells, were also investigated. Western blot analysis revealed COX-2 protein to be barely expressed in the normal epithelial cells, whereas it was increased 13-22-fold in varying sizes of urinary bladder tumors and 7-fold in papillomatosis. Immunohistochemically, COX-2 protein was diffusely expressed in transitional cell carcinomas and nodulo-papillary hyperplasia but weakly expressed only in basal cells in simple hyperplasia and normal-looking surrounding epithelia. In papillomatosis, it was moderately expressed only in endothelial cells in stroma. These results indicate that COX-2 plays important roles in the development of preneoplastic and neoplastic lesions in the rat urinary bladder, and therefore could be a good target for chemoprevention of superficial lesions.  (+info)

Aberrant expression of p27(Kip1) is associated with malignant transformation of the rat urinary bladder epithelium. (8/87)

Alteration in cell cycle regulators is considered to play an important role in carcinogenesis. In order to cast light on changes in reversible hyperplastic and irreversible tumorigenic lesions in the rat urinary bladder, expression of p27(Kip1), cyclin D1 and cyclin E proteins was sequentially compared. In the first study, 3% uracil was fed for 4 weeks to cause urinary calculi and consequent hyperplasia and papillomatosis, both regressing after withdrawal of the insult. Compared with normal bladder epithelium, in papillomatosis at week 4, the BrdU index and immunohistochemical positivities for cyclin D1 and cyclin E were significantly elevated, whereas values for p27(Kip1) tended to be reduced. One week after withdrawal of uracil, the BrdU index and positivities for cyclin D1 and cyclin E were decreased to below the control levels, while positivity for p27(Kip1) was dramatically increased, with a strong staining intensity. In a second study, rats were initiated with a bladder carcinogen, N-butyl-N-(4-hydroxybutyl)nitrosamine for 4 weeks, then fed 3% uracil for 8 weeks. During this latter period, expression of cyclin D1, cyclin E and p27(Kip1) in hyperplastic urothelium were comparable with those in the first study. One week after withdrawal of uracil, most urothelial lesions regressed, showing high p27(Kip1) and low cyclin D1 and cyclin E staining. Two weeks after uracil withdrawal, transitional cell carcinomas, with a low p27(Kip1) and high cyclin D1 and cyclin E staining pattern, could be easily distinguished from surrounding regressing epithelium. These data indicate that during regression of papillomatosis after cessation of a proliferative stimulus, expression of p27(Kip1)is elevated, accompanied by a lowering of cyclin D1 and cyclin E. In irreversible tumorous bladder lesions, on the other hand, persistent low expression of p27(Kip1) and elevated cyclin D1 and cyclin E are characteristic.  (+info)

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