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

Preclinical models of bladder cancer: BBN and beyond

Preclinical modelling is a crucial component of advancing the understanding of cancer biology and therapeutic development. Several models exist for understanding the pathobiology of bladder cancer and evaluating therapeutics. N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)-induced bladder cancer is a commonly used model that recapitulates many of the features of human disease. Particularly in mice, BBN is a preferred laboratory model owing to a high level of reproducibility, high genetic fidelity to the human condition, and its relative ease of use. However, important aspects of the model are often overlooked in laboratory studies. Moreover, the advent of new models has yielded a variety of methodologies that complement the use of BBN. Toxicokinetics, histopathology, molecular genetics and sex can differ between available models and are important factors to consider in bladder cancer modelling.

Selective targeting of lectins and their macropinocytosis in urothelial tumours: translation from in vitro to ex vivo

Urinary bladder cancer can be treated by intravesical application of therapeutic agents, but the specific targeting of cancer urothelial cells and the endocytotic pathways of the agents are not known. During carcinogenesis, the superficial urothelial cells exhibit changes in sugar residues on the apical plasma membranes. This can be exploited for selective targeting from the luminal side of the bladder. Here we show that the plant lectins Jacalin (from Artocarpus integrifolia), ACA (from Amaranthus caudatus) and DSA (from Datura stramonium) selectively bind to the apical plasma membrane of low- (RT4) and high-grade (T24) cancer urothelial cells in vitro and urothelial tumours ex vivo. The amount of lectin binding was significantly different between RT4 and T24 cells. Endocytosis of lectins was observed only in cancer urothelial cells and not in normal urothelial cells. Transmission electron microscopy analysis showed macropinosomes, endosome-like vesicles and multivesicular bodies filled with lectins in RT4 and T24 cells and also in cells of urothelial tumours ex vivo. Endocytosis of Jacalin and ACA in cancer cells was decreased in vitro after addition of inhibitor of macropinocytosis 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and increased after stimulation of macropinocytosis with epidermal growth factor (EGF). Clathrin, caveolin and flotillin did not colocalise with lectins. These results confirm that the predominant mechanism of lectin endocytosis in cancer urothelial cells is macropinocytosis. Therefore, we propose that lectins in combination with conjugated therapeutic agents are promising tools for improved intravesical therapy by targeting cancer cells.

Early detection of urinary bladder carcinogens in rats by immunohistochemistry for γ-H2AX: a review from analyses of 100 chemicals

In safety evaluations of chemicals, there is an urgent need to develop short-term methods to replace long-term carcinogenicity tests. We have reported that immunohistochemistry for γ-H2AX, a well-established biomarker of DNA damage, can detect bladder carcinogens at an early stage using histopathological specimens from 28-day repeated-dose oral toxicity studies in rats. Given the markedly low level of γ-H2AX formation in the bladder urothelium of untreated rats, an increase in γ-H2AX-positive cells following chemical exposure can be relatively easy to identify. Among the 100 compounds examined to date, bladder carcinogens can be detected with high sensitivity (33/39; 84.6%) and specificity (58/61; 95.1%). As expected, γ-H2AX formation levels tended to be high following exposure to genotoxic bladder carcinogens, whereas nongenotoxic bladder carcinogens also increased the number of γ-H2AX-positive cells, probably through secondary DNA damage associated with sustained proliferative stimulation. γ-H2AX formation in the bladder urothelium reflects species differences in susceptibility to bladder carcinogenesis between rats and mice and shows a clear dose-dependency associated with the intensity of tumor development as well as high reproducibility. Some of the bladder carcinogens that showed false-negative results in the evaluation of γ-H2AX alone could be detected by combined evaluation with immunostaining for bladder stem cell markers, including aldehyde dehydrogenase 1A1. This method may be useful for the early detection of bladder carcinogens, as it can be performed by simple addition of conventional immunostaining using formalin-fixed paraffin-embedded tissues from 28-day repeated-dose toxicity studies in rodents, which are commonly used in safety evaluations of chemical substances.

Metastatic urothelial carcinoma of the urinary bladder in a Sumatran tiger (Panthera tigris sondaica)

A 15-year-old spayed female Sumatran tiger (Panthera tigris sondaica) was presented with a short history of haematuria and dysuria, non-responsive to antibiotics, and a gradual decline to inappetence over a period of 2-3 months. Ultrasound examination showed a thickened urinary bladder wall and the renal pelvis of right kidney was dilated and cystic. A presumptive diagnosis of renal failure was made, and the tigress was euthanised due to deteriorating quality of life and pronounced weight loss. Histopathology revealed extensive erosion of the urinary bladder wall and marked congestion of the submucosal vasculature, a potential cause of the haematuria observed clinically. Numerous foci of neoplastic cells were also observed throughout the lung parenchyma as well as within lymphatic vessels of the lung, the liver and the kidney. A diagnosis of a metastatic non-papillary high-grade urothelial carcinoma (UC) of the urinary bladder was made. Consistent with this diagnosis, immunohistochemistry revealed the neoplastic cells were negative for uroplakin III, as has been reported for a subset of high-grade, infiltrative urinary bladder UCs of canines and humans. This is the first report of a primary tumour of the urinary bladder in a tiger and the first report of UC in a tiger.

[Role and potential of histopathological specimens in the toxicological evaluation of pharmaceuticals and chemicals]

With the development of molecular-targeted drugs, the demand for utilization of histopathological specimens and pathological diagnosis is increasing in the field of clinical pathology. In particular, in case of companion diagnostics, the results of immunohistochemical staining have become beyond diagnostic assistance, definitive diagnosis, and now indispensable for selection of therapeutic agents. Histopathological examination also serves an important role in non-clinical toxicological evaluation. Particularly, it is pivotal for obtaining data on organ-specific toxicity and carcinogenicity. On the other hand, a weight of evidence approach is currently being considered in International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) S1 as an option to replace the 2-year rat carcinogenicity study, in which case the evaluation of the 26-week-repeated dose toxicity study will be more important. In this article, We would like to introduce the usefulness of γ-H2AX-based rat bladder carcinogenicity evaluation using histopathological specimens obtain from 28-day repeated-dose study and the application of mass spectrometric imaging currently under consideration in our laboratory, thus discuss the role of histopathological examination in non-clinical toxicological and safety evaluation and its future perspective.

Reciprocal regulation of HIF-1α and Uroplakin 1A promotes glycolysis and proliferation in Hepatocellular Carcinoma

Uroplakin 1A (UPK1A) has recently been found dysregulation in many cancers. However, the functions of UPK1A and its underlying mechanisms in hepatocellular carcinoma (HCC) remain poorly understand. In the present study, we found that UPK1A was highly expressed in HCC tumor tissues compared with adjacent non-tumor tissues. Datasets from the Cancer Genome Atlas project (TCGA) and Gene expression Omnibus confirmed that UPK1A was highly expressed in HCC. High expression of UPK1A predicted poor overall survival (OS) in patients with HCC. Univariate and multivariate analysis showed that UPK1A was a significant and independent prognostic predictor for OS of patients with HCC. Functionally, silencing UPK1A suppressed HCC cell glycolysis and proliferation. Mechanistically, hypoxia-inducible factor 1α (HIF-1α) directly bound to the hypoxia response elements (HRE) of UPK1A promoter region, which led to the up-regulation of UPK1A under hypoxia. Furthermore, downregulation of UPK1A reduced key enzyme of glycolysis via regulating HIF-1α. Taken together, these data indicates the existence of a positive feedback loop between HIF-1α and UPK1A that modulates glycolysis and proliferation under hypoxia in HCC cells.

Combined lectin- and immuno-histochemistry (CLIH) for applications in cell biology and cancer diagnosis: Analysis of human urothelial carcinomas

Lectin histochemistry (LHC) and immunohistochemistry (IHC), which demonstrate the composition and localisation of sugar residues and proteins in cell membranes, respectively, are generally used separately. Using these two methods, we previously demonstrated that malignant transformation of urothelial cells results in the alterations of protein glycosylation and reduced expression of urothelium-specific integral membrane proteins uroplakins (UPs). However, the correlation between these changes was not studied yet. To evaluate this correlation, we developed innovative method, which we named Combined Lectin- and Immuno-Histochemistry (CLIH). We used human biopsies of 6 normal urothelia and 9 papillary urothelial carcinomas, i.e. 3 papillary urothelial neoplasms of low malignant potential (PUNLMP), 3 non-invasive papillary urothelial carcinomas of low grade (pTa, l.g.), and 3 invasive papillary urothelial carcinomas of high grade (pT1, h.g.). We tested five different protocols (numbered 1-5) of CLIH on paraffin and cryosemithin sections and compared them with LHC and IHC performed separately. Additionally, we carried out western and lectin blotting with antibodies against UPs and lectins Amaranthus caudatus agglutinin (ACA), Datura stramonium agglutinin (DSA), and jacalin, respectively. We showed that incubation with primary antibodies first, followed by the mixture of secondary antibodies and lectins is the most efficient CLIH method (protocol number 5). Additionally, 300 nm thick cryo-semithin sections enabled better resolution of co-localisation between sugar residues and proteins than 5 mm thick paraffin sections. In the normal urothelium, CLIH showed co-localisation of lectins ACA and jacalin with UPs in the apical plasma membrane (PM) of superficial umbrella cells. In papillary urothelial carcinomas, all three lectins (ACA, DSA and jacalin) labelled regions of apical PM, where they occasionally co-localised with UPs. Western and lectin blotting confirmed the differences between normal urothelium and papillary urothelial carcinomas. Our results show that CLIH, when used with various sets of lectins and antigens, is a useful, quick, and reliable method that could be applied for basic cell biology research as well as detailed subtyping of human urothelial carcinomas.

Vitamin A Rich Diet Diminishes Early Urothelial Carcinogenesis by Altering Retinoic Acid Signaling

Urinary bladder cancer is one of the leading malignancies worldwide, with the highest recurrence rates. A diet rich in vitamin A has proven to lower the risk of cancer, yet the molecular mechanisms underlying this effect are unknown. We found that vitamin A decreased urothelial atypia and apoptosis during early bladder carcinogenesis induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). Vitamin A did not alter urothelial cell desquamation, differentiation, or proliferation rate. Genes like Wnt5a, involved in retinoic acid signaling, and transcription factors Pparg, Ppara, Rxra, and Hoxa5 were downregulated, while Sox9 and Stra6 were upregulated in early urothelial carcinogenesis. When a vitamin A rich diet was provided during BBN treatment, none of these genes was up- or downregulated; only Lrat and Neurod1 were upregulated. The lecithin retinol acyltransferase (LRAT) enzyme that produces all-trans retinyl esters was translocated from the cytoplasm to the nuclei in urothelial cells as a consequence of BBN treatment regardless of vitamin A rich diet. A vitamin A-rich diet altered retinoic acid signaling, decreased atypia and apoptosis of urothelial cells, and consequently diminished early urothelial carcinogenesis.

ATG7 Overexpression Is Crucial for Tumorigenic Growth of Bladder Cancer In Vitro and In Vivo by Targeting the ETS2/miRNA196b/FOXO1/p27 Axis

Human bladder cancer (BC) is the fourth most common cancer in the United States. Investigation of the strategies aiming to elucidate the tumor growth and metastatic pathways in BC is critical for the management of this disease. Here we found that ATG7 expression was remarkably elevated in human bladder urothelial carcinoma and N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced mouse invasive BC. Knockdown of ATG7 resulted in a significant inhibitory effect on tumorigenic growth of human BC cells both in vitro and in vivo by promoting p27 expression and inducing cell cycle arrest at G2/M phase. We further demonstrated that knockdown of ATG7 upregulated FOXO1 (forkhead box protein O 1) expression, which specifically promoted p27 transcription. Moreover, mechanistic studies revealed that inhibition of ATG7 stabilized ETS2 mRNA and, in turn, reduced miR-196b transcription and expression of miR-196b, which was able to bind to the 3' UTR of FOXO1 mRNA, consequently stabilizing FOXO1 mRNA and finally promoting p27 transcription and attenuating BC tumorigenic growth. The identification of the ATG7/FOXO1/p27 mechanism for promoting BC cell growth provides significant insights into understanding the nature of BC tumorigenesis. Together with our most recent discovery of the crucial role of ATG7 in promoting BC invasion, it raises the potential for developing an ATG7-based specific therapeutic strategy for treatment of human BC patients.

Immunohistochemical Expression of Cyclin D1, Cytokeratin 20, and Uroplakin III in Proliferative Urinary Bladder Lesions Induced by o-Nitroanisole in Fischer 344/N Rats

o-Nitroanisole is an intermediate in the manufacture of azo dyes. In a National Toxicology Program stop-exposure study,o-nitroanisole induced hyperplasia, papillomas, and papillary carcinomas in the urinary bladder of Fischer 344/N rats.o-Nitroanisole was investigated since occupational or environmental exposure to aniline and azo dyes is a risk factor for urinary bladder cancer in humans. The current study describes the morphology of urinary bladder neoplasms seen in rats with respect to those observed in humans. This study also evaluated immunohistochemical expression of the cell cycle-related proteins cyclin D1 and p53 and the differentiation markers cytokeratin 20 and uroplakin III in hyperplastic (n= 11) and neoplastic (n= 6 papillomas,n= 11 carcinomas) lesions of the urinary bladder epithelium from rats treated with o-nitroanisole and in normal (n= 6) urinary bladders from untreated rats. The tumors observed were more similar to the papillary type rather than the muscle-invasive type of urinary bladder cancer in humans. The preneoplastic and neoplastic lesions observed suggest progression from hyperplasia to papilloma to papillary carcinoma. With neoplastic progression (hyperplasia to papilloma to carcinoma), cyclin D1 immunoreactivity progressively increased in intensity, percentage of cells staining, and distribution. Overexpression of p53 was not found. Cytokeratin 20 staining decreased in superficial cells, while uroplakin III staining increased in intermediate and basal cells with progression from hyperplasia to carcinoma. The results are consistent with increased cell cycle dysregulation or proliferation (cyclin D1), decreased differentiation (cytokeratin 20), and abnormal differentiation (uroplakin III) as lesions progress toward malignancy.

Bladder cancers arise from distinct urothelial sub-populations

Bladder cancer is the sixth most common cancer in humans. This heterogeneous set of lesions including urothelial carcinoma (Uca) and squamous cell carcinoma (SCC) arise from the urothelium, a stratified epithelium composed of K5-expressing basal cells, intermediate cells and umbrella cells. Superficial Uca lesions are morphologically distinct and exhibit different clinical behaviours: carcinoma in situ (CIS) is a flat aggressive lesion, whereas papillary carcinomas are generally low-grade and non-invasive. Whether these distinct characteristics reflect different cell types of origin is unknown. Here we show using lineage tracing in a murine model of carcinogenesis that intermediate cells give rise primarily to papillary lesions, whereas K5-basal cells are likely progenitors of CIS, muscle-invasive lesions and SCC depending on the genetic background. Our results provide a cellular and genetic basis for the diversity in bladder cancer lesions and provide a possible explanation for their clinical and morphological differences.

Urothelial carcinogen resistance driven by stronger Toll-like receptor 2 (TLR2) and Uroplakin III (UP III) defense mechanisms: a new model

OBJECTIVE

The objective of the study was to illustrate the applicability and significance of the novel Lewis urothelial cancer model compared to the classic Fisher 344.

METHODS

Fischer 344 and Lewis females rats, 7 weeks old, were intravesical instilled N-methyl-N-nitrosourea 1.5 mg/kg every other week for a total of four doses. After 15 weeks, animals were sacrificed and bladders analyzed: histopathology (tumor grade and stage), immunohistochemistry (apoptotic and proliferative indices) and blotting (Toll-like receptor 2-TLR2, Uroplakin III-UP III and C-Myc). Control groups received placebo.

RESULTS

There were macroscopic neoplastic lesions in 20 % of Lewis strain and 70 % of Fischer 344 strain. Lewis showed hyperplasia in 50 % of animals, normal bladders in 50 %. All Fischer 344 had lesions, 20 % papillary hyperplasia, 30 % dysplasia, 40 % neoplasia and 10 % squamous metaplasia. Proliferative and apoptotic indices were significantly lower in the Lewis strain (p < 0.01). The TLR2 and UP III protein levels were significantly higher in Lewis compared to Fischer 344 strain (70.8 and 46.5 % vs. 49.5 and 16.9 %, respectively). In contrast, C-Myc protein levels were significantly higher in Fischer 344 (22.5 %) compared to Lewis strain (13.7 %).

CONCLUSIONS

The innovative Lewis carcinogen resistance urothelial model represents a new strategy for translational research. Preservation of TLR2 and UP III defense mechanisms might drive diverse urothelial phenotypes during carcinogenesis in differently susceptible individuals.

SLCO1B1, SLCO2B1, and SLCO1B3 polymorphisms and susceptibility to bladder cancer risk

A variety of carcinogens are excreted in urine and may be actively transported by organic anion-transporting polypeptides that encoded by SLCOs. In this study, we evaluated whether single nucleotide polymorphisms (SNPs) in SLCO1B1, SLCO2B1, and SLCO1B3 are associated with bladder cancer susceptibility. Our results, for the first time, indicated that polymorphisms of SLCO1B1 rs2306283 might be associated with bladder cancer risk. Therefore, SNPs in SLCO1B1 may be potential biomarkers for assessing the risk of bladder cancer.

Selective binding of lectins to normal and neoplastic urothelium in rat and mouse bladder carcinogenesis models

Bladder cancer adjuvant intravesical therapy could be optimized by more selective targeting of neoplastic tissue via specific binding of lectins to plasma membrane carbohydrates. Our aim was to establish rat and mouse models of bladder carcinogenesis to investigate in vivo and ex vivo binding of selected lectins to the luminal surface of normal and neoplastic urothelium. Male rats and mice were treated with 0.05 % N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in drinking water and used for ex vivo and in vivo lectin binding experiments. Urinary bladder samples were also used for paraffin embedding, scanning electron microscopy and immunofluorescence labelling of uroplakins. During carcinogenesis, the structure of the urinary bladder luminal surface changed from microridges to microvilli and ropy ridges and the expression of urothelial-specific glycoproteins uroplakins was decreased. Ex vivo and in vivo lectin binding experiments gave comparable results. Jacalin (lectin from Artocarpus integrifolia) exhibited the highest selectivity for neoplastic compared to normal urothelium of rats and mice. The binding of lectin from Amaranthus caudatus decreased in rat model and increased in mouse carcinogenesis model, indicating interspecies variations of plasma membrane glycosylation. Lectin from Datura stramonium showed higher affinity for neoplastic urothelium compared to the normal in rat and mouse model. The BBN-induced animal models of bladder carcinogenesis offer a promising approach for lectin binding experiments and further lectin-mediated targeted drug delivery research. Moreover, in vivo lectin binding experiments are comparable to ex vivo experiments, which should be considered when planning and optimizing future research.

Heterogeneity of uroplakin localization in human normal urothelium, papilloma and papillary carcinoma

Background

Uroplakins are differentiation-related membrane proteins of urothelium. We compared uroplakin expression and ultrastructural localization in human normal urothelium, papilloma and papillary carcinoma. Because of high recurrence rate of these tumours, treated by transurethral resection, we investigated urothelial tumour, resection border and uninvolved urothelium.

Patients and methods

Urinary bladder samples were obtained from tumour free control subjects and patients with papilloma and papillary carcinoma. Immunohistochemical and immunoelectron labelling of uroplakins were performed.

Results

In normal human urothelium with continuous uroplakin-positive superficial cell layer uroplakins were localized to flattened mature fusiform vesicles and apical plasma membrane of umbrella cells. Diverse uroplakin expression was found in papilloma and papillary carcinoma. Three aberrant differentiation stages of urothelial cells, not found in normal urothelium, were recognized in tumours. Diverse uroplakin expression and aberrant differentiation were occasionally found in resection border and in uninvolved urothelium.

Conclusions

We demonstrated here that uroplakin expression and localization in urothelial tumours is altered when compared to normal urothelium. In patients with papilloma and papillary carcinoma immunolabelling of uroplakins at ultrastructural level shows aberrant urothelial differentiation. It is possible that aberrant differentiation stages of urothelial cells in resection border and in uninvolved urothelium contribute to high recurrence rate.

Epithelial Urinary Bladder Tumors From Cows With Enzootic Hematuria

Thirty-nine epithelial bladder tumor samples from 37 animals affected with bovine enzootic hematuria (BEH) were selected for immunohistochemical studies. The expression of structural proteins such as uroplakin III (UPIII) and cytokeratin 7 (CK7) and the cell cycle–related proteins cyclin D1 and p53 were evaluated in urothelial papillomas and carcinomas. Loss of UPIII and CK7 expression was seen in both high-grade and high-stage urothelial carcinomas ( P < .001 and P < .02). Cyclin D1 expression showed no statistically significant association with grade or stage. In contrast, p53 immunoreactivity was positive in high-grade and high-stage carcinomas ( P < .05 and P < .01), confirming its association with the highest malignant behavior of the bladder tumors in BEH.

Tissue-specific mutagenesis by N-butyl-N-(4-hydroxybutyl)nitrosamine as the basis for urothelial carcinogenesis

Bladder cancer is one of the few cancers that have been linked to carcinogens in the environment and tobacco smoke. Of the carcinogens tested in mouse chemical carcinogenesis models, N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) is one that reproducibly causes high-grade, invasive cancers in the urinary bladder, but not in any other tissues. However, the basis for such a high-level tissue-specificity has not been explored. Using mutagenesis in lacI (Big Blue™) mice, we show here that BBN is a potent mutagen and it causes high-level of mutagenesis specifically in the epithelial cells (urothelial) of the urinary bladder. After a 2-6-week treatment of 0.05% BBN in the drinking water, mutagenesis in urothelial cells of male and female mice was about two orders of magnitude greater than the spontaneous mutation background. In contrast, mutagenesis in smooth muscle cells of the urinary bladder was about five times lower than in urothelial tissue. No appreciable increase in mutagenesis was observed in kidney, ureter, liver or forestomach. In lacI (Big Blue™) rats, BBN mutagenesis was also elevated in urothelial cells, albeit not nearly as profoundly as in mice. This provides a potential explanation as to why rats are less prone than mice to the formation of aggressive form of bladder cancer induced by BBN. Our results suggest that the propensity to BBN-triggered mutagenesis of urothelial cells underlies its heightened susceptibility to this carcinogen and that mutagenesis induced by BBN represents a novel model for initiation of bladder carcinogenesis.

Altered expression of UPIa, UPIb, UPII, and UPIIIa during urothelial carcinogenesis induced by N-butyl-N-(4-hydroxybutyl)nitrosamine in rats

In normal urothelium, superficial umbrella cells express four major integral membrane proteins, uroplakins UPIa, UPIb, UPII, and UPIIIa, which compose urothelial plaques. In the apical plasma membrane, urothelial plaques form microridges. During neoplastic changes, microridges are replaced by microvilli, while uroplakin expression is retained. We correlated individual uroplakin expression with apical plasma membrane structure, cytokeratin 20 expression, and urothelial cell proliferation (Ki-67). Male Wistar rats were treated with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in drinking water, which caused flat hyperplasia with mild dysplasia, low-grade papillary urothelial carcinoma, invasive low- and high-grade papillary urothelial carcinoma and invasive squamous cell carcinoma with extensive keratinization, grade 2. During urothelial carcinogenesis, UPII expression was the most decreased in all urothelial lesions, while UPIa, UPIb, and UPIIIa expression was differently altered in different types of lesions. Superficial cells were covered with microvilli and ropy ridges, while microridges were disappearing. The expression of cytokeratin 20 was decreased and limited to superficial urothelial cells. Proliferation indices were increased, except for invasive squamous cell carcinoma with extensive keratinization. Our results indicate that during urothelial carcinogenesis the expression of UPII is diminished, suggesting that UPIb/UPIIIa heterodimer can still be formed, while heterodimer UPIa/UPII formation is disrupted. Correlation between decreased level of UPII expression and changed apical plasma membrane structure suggests that diminished expression of UPII hinders the urothelial plaque formation.

Different immunohistochemical and ultrastructural phenotypes of squamous differentiation in bladder cancer

Besides worse prognosis of bladder cancer with squamous differentiation (pure squamous cell carcinoma (SCC) or mixed urothelial carcinoma (UC/SCC)), high-grade non-keratinising squamous differentiation is difficult to identify in haematoxylin-eosin stainings. This study aims to validate routine immunohistochemical markers for squamous differentiation in a larger cohort of patients. Tissue microarrays of 89 pure SCCs and mixed UC/SCCs, 66 urothelial carcinomas (UC), precursor lesions and normal urothelium were stained for cytokeratin (CK) 5/6, CK 5/14, CK 7, CK 20 and uroplakin III. Electron microscopy was performed to confirm the differentiation. Pure SCCs displayed staining throughout the epithelium for CK 5/6 (76.6% (36/47)) and CK 5/14 (95.8% (46/48)), focal staining for CK 7 (28.9% (13/45)) and no staining for CK 20 and uroplakin III (both 0% (0/48)). UCs exhibited a basal or diffuse staining for CK 5/6 (30.2% (16/53)) and CK 5/14 (57.1% (32/56)), focal positivity for CK 7 (83.6% (46/55)), CK 20 (50.9% (29/57)) and uroplakin III (21.8% (12/55)). Each marker discriminated SCC and UC significantly (p < 0.01). A third subgroup rarely showed full epithelial staining for CK 5/6 (14.3% (1/7)) and CK 5/14 (28.6% (2/7)), focal staining for CK 7 (85.7% (6/7)) and no staining for CK 20 and uroplakin III (both 0% (0/7)). Electron microscopy could prove both, SCC and UC characteristics, revealing a transient type. A staining pattern with CK 5/6- and CK 5/14-positivity plus CK 20- and uroplakin III-negativity identified squamous differentiation in bladder tumours and revealed a third type of squamous transdifferentiation.

Bovine papillomavirus type-2 (BPV-2) infection and expression of uroplakin IIIb, a novel urothelial cell marker, in urinary bladder tumors of cows

Several immunohistochemical markers have been used to define the differentiation pattern of urothelial cell tumors of the urinary bladder. We investigated the expression of the recently characterized uroplakin (UP) IIIb, an urothelium-specific and differentiation-dependent protein, in 39 urothelial tumors of the urinary bladder in cows that had suffered from chronic enzootic hematuria for several years. Bovine papillomavirus type 2 DNA was amplified and UP IIIb protein was detected in all these tumors. In papillomas and papillary carcinomas, UP IIIb expression was mostly seen as superficial staining; luminal and peripheral patterns were also observed. In nonpapillary carcinomas, UP IIIb appeared to define clearly the cell membrane lining intercellular and intracellular lumina as well as the cell borders in deeper cell layers. In benign and malignant lesions, an intracytoplasmic immunoreactivity was also detected. Coarse intracytoplasmic UP IIIb-positive material close to the nucleus occurred in some malignant cells. Focally strong membraneous immunostaining that marked single cells with complete ringlike peripheral pattern was seen. Although UP IIIb expression does not seem to correlate with the biological behavior of urothelial tumors, it appears to be a highly sensitive marker for bovine urothelial tumors.

Immunohistochemical detection of uroplakin III, cytokeratin 7, and cytokeratin 20 in canine urothelial tumors

Immunohistochemistry for uroplakin III (UP III), cytokeratin 7 (CK 7), and cytokeratin 20 (CK 20) using commercially available antibodies was done in normal canine urinary bladder and 72 canine urinary bladder tumors that had been fixed in formalin and embedded in paraffin. Prolonged fixation (3-28 days) did not significantly alter the immunostaining for UP III. There was moderate reduction in the intensity for CK 7 and CK 20 after 1 week of fixation. UP III was detected in superficial (umbrella) cells and some intermediate cells of the normal urinary bladder, 7 of 7 transitional cell papillomas (TCPs), 50 of 55 transitional cell carcinomas (TCCs), and 4 of 5 metastatic TCCs. Staining was typically outlined in the plasma membrane, but diffuse or focal cytoplasmic staining was also observed. Intracytoplasmic lumina were usually positive for UP III. One squamous cell carcinoma of the bladder, 4 nonepithelial bladder tumors, and 285 nonurothelial tumors from different nonurinary locations were negative for UP III. CK 7 was detected in 7 of 7 TCPs, 53 of 54 TCCs, and 5 of 5 metastatic TCCs. The staining for CK 7 was diffuse cytoplasmic. CK 20 was detected in 1 of 7 TCPs, 37 of 54 TCCs, and 1 of 5 metastatic TCCs. The staining with CK 20 was cytoplasmic and weaker than with antibodies to UP III or CK 7. There was concurrent expression of UP III, CK 7, and CK 20 in 36 of 54 TCCs. UP III is a specific and sensitive marker for canine transitional epithelial (urothelial) neoplasms, detecting 91% of TCCs. Negative results may be observed with anaplastic tumors.

High expression of human uroplakin Ia in urinary bladder transitional cell carcinoma

Uroplakins (UPs) Ia, Ib, II, and III are tissue-specific and differentiation-dependent transmembrane proteins of the urothelium. We assessed the usefulness of human UP Ia as a histological marker by examining its expression in urinary bladder transitional cell carcinoma (TCC). A polyclonal antibody against human UP Ia was raised using a synthesized polypeptide. We applied our antibody to various organ tissues, including urothelium, and observed no crossreactivity. Analysis by RT-PCR of normal urothelium, TCC and other organ tissues indicated that the human UP Ia gene expression is highly specialized to urothelium, and is conserved in TCC. Using immunohistochemistry, we investigated the expression of UP Ia in TCC from patients who had undergone radical cystectomy and from autopsy cases. Positive staining (10% or more positive cancer cells) was noted in primary lesions from 61 of 63 (96.8%) cystectomy patients. Depending on pathological grade, high expression (50% or more positive cancer cells) was observed in 17 of 18 (94.4%) moderately- to well-differentiated TCC and in 36 of 45 (80.0%) poorly differentiated TCC. With regard to tumor invasion, high expression was noted in 20 of 22 (90.9%) superficial and 33 of 41 (80.5%) muscle-invasive TCC. Cause-specific survival rates were 68.6% and 75.0% in high- and low-expression patients, respectively (log-rank test, P = 0.855, mean follow-up; 65.0 months). In metastases, positive reactions were observed in 13 of 18 (72.2%) lesions. UP Ia may represent a specific histological marker judging from the stable expression, although its value as a prognostic factor remains undetermined.

Uroplakin expression in the urothelial tumors of cows

Expression of uroplakins (UPs) was investigated in 20 bladder tumors from cows that had been suffering from chronic enzootic hematuria for several years. In dysplastic urothelium and papillomatous proliferations, UP expression was evident both as luminal and intercellular staining. UPs appeared to clearly define the plasma membrane of luminal cells and the borders of cells placed in deeper layers, whether or not these intermediate cells were adjacent to superficial ones. Occasionally, some intermediate cells showed a remarkable cytoplasmic immunoreactivity. The pattern of UPs in grade I tumors was characterized by an evident discontinuity of luminal staining and by the presence of numerous intermediate cells showing a diffuse intracytoplasmic positivity for UPs. In grade II tumors, there was a decrease of luminal and intermediate cells showing UP expression and an apparent increase of clusters of intermediate cells with intracytoplasmic reactivity for UPs. In grade III tumors, immunoreactivity was heterogeneously distributed and a severe loss of UP-positive luminal and intermediate cells could be seen. Focally, superficial and deeper cells showed strong membraneous immunoreactivity that marked and delimited single cells, with complete circumferential peripheral staining clearly evident. UP expression in bladder tumors of cows reported in this study is similar to the UP pattern of some urothelial tumors in humans. Although UP expression is remarkably changed in bladder carcinogenesis of cattle, the UP gene(s) remains expressed during cell transformation and tumor progression.