E-cadherin and β-catenin expression during urothelial carcinogenesis induced by N-butyl-N-(4-hydroxybutyl) nitrosamine in mice

BACKGROUND

E-cadherin and β-catenin are adhesion molecules that promote integrity and stability of the urothelium. A decrease in their expression is associated with more aggressive tumour phenotypes with the ability to invade and metastasize.

MATERIAL AND METHODS

45 ICR male mice were used, of which 25 received N-butyl-N-(4-hydroxybutyl)nitrosamine (0.05%) in drinking water for a period of 12 weeks. Immunohistochemical expression was evaluated in all urinary bladder preparations for E-cadherin and for β-catenin.

RESULTS

Preneoplastic lesions showed staining patterns similar to normal urothelium. In simple and nodular hyperplasia, membrane staining was dominant (66.7-78.6 and 50-100%, respectively). In dysplasia a cytoplasmic pattern was prevalent (86.7-100%). Neoplastic lesions exhibit an abnormal staining pattern (100%) with heterogeneous staining (cytoplasmic, nuclear and membrane staining). A strong correlation was observed between both adhesion molecule staining patterns (r = 0.83; p = 0.039).

CONCLUSIONS

In mice, as in humans, E-cadherin and β-catenin are valuable tools to investigate cellular adhesion status of urothelium and can be considered as indicators of tumour aggressiveness and evolution.

Review: BBN as an urothelial carcinogen

Experimental urinary bladder tumours have been proposed as a useful model for the study of urinary bladder carcinogenesis, as well as for evaluating new therapeutic strategies. Consequently, the administration of chemical carcinogens is one of the most commonly used methods for inducing urinary bladder tumours. N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) is, undoubtedly, the most-used urothelial chemical carcinogen. BBN belongs to the nitrosamine family, a wide group of alkylating agents that are able to induce bladder tumours in laboratory animals. Depending on the animal species, the spectrum of urothelial lesions induced by BBN varies, but is similar to those observed in humans. BBN has a high propensity to induce mutations affecting the expression of genes such as p53, RAS and H19 among others. The aim of this study was to review BBN as a urothelial tumour inducer, taking into consideration its chemical characteristics, properties and spectrum of lesions induced, as well as its possible applications.

Experimental study of the anticancer effect of gemcitabine combined with sirolimus on chemically induced urothelial lesions

BACKGROUND

The purpose of this study was to determine the efficacy of a combination of gemcitabine and sirolimus in a mouse model of invasive bladder cancer.

MATERIALS AND METHODS

Gemcitabine (50 mg/kg) and sirolimus (1.5 mg/kg) were administered to animals previously exposed to N-butyl-N-4(hydroxybutyl)nitrosamine in drinking water. Tumour development was determined by histopathological evaluation.

RESULTS

Both drugs were well tolerated by animals. The incidence of lesions in mice treated with gemcitabine was lower in comparison to those not treated, however this result was not statistically significant. The incidence of invasive bladder cancer in animals treated with sirolimus was statistically lower (20%) than in animals not treated (54%) (p=0.008). The results indicate that this drug combination has no statistical significance on the development of pre-neoplastic urothelial lesions and had only a minor impact on invasive bladder cancer incidence in mice.

CONCLUSION

The combination of gemcitabine and sirolimus had only a marginal impact on invasive bladder cancer in a mouse model.