Proliferative activity of normal and neoplastic urothelium and its relation to epidermal growth factor and transferrin receptors

Radiation effects on cellularity, proliferation and EGFR expression in mouse bladder urothelium

This study was designed to determine changes in cell numbers, proliferation (using Ki-67) and EGFR expression in mouse bladder urothelium during the early and late radiation response. Groups of mice were irradiated with a single dose of 20 Gy and assayed 0-360 days later. Urothelial cells were counted. After immunohistochemistry, the absolute and relative numbers of Ki-67(+) and EGFR(+) cells were analyzed. Radiation exposure resulted in a decrease in total urothelial cell numbers to 49% by day 31, with restoration of cellularity by day 180. In contrast, at day 360, an increase in total cell number (143%) was seen. Slightly increased Ki-67 expression was found at days 120 and 180 after treatment, followed by a pronounced elevation at days 240 and 360. Compared to controls, higher EGFR expression was detected up to day 360 after irradiation. A positive correlation was found between total urothelial cells numbers and Ki-67 as well as EGFR expression. Radiation exposure results in an increased urothelial expression of EGFR that precedes urothelial restoration, indicating a contribution of the EGF/EGFR system to urothelial proliferation and differentiation. Further studies are needed to evaluate the impact of EGFR inhibition on radiation effects in the urinary bladder.

Experimental models of human bladder carcinogenesis

Bladder cancer is the fifth most common cancer in the UK, yet human bladder carcinogenesis remains poorly understood and the response of bladder tumours to radio- and chemo-therapy is unpredictable. The aims of this article are to review human bladder carcinogenesis and appraise the different in vitro and in vivo approaches that have been developed to study the process. The review considers how in vitro models based on normal human urothelial (NHU) cells can be applied to human bladder cancer research. We conclude that recent advances in NHU cell culture offer novel approaches for defining urothelial tissue-specific responses to genotoxic and non-genotoxic carcinogens and elucidating the role of specific genes involved in the mechanisms of bladder carcinogenesis and malignant progression.

Evaluation of epidermal growth factor receptor, transforming growth factor alpha, epidermal growth factor and c-erbB2 in the progression of invasive bladder cancer

INTRODUCTION

Determination of the risk of invasive bladder tumors progressing is still imprecise due to the heterogeneous biological behavior of this neoplasm. The goals of this study were to evaluate the patterns of expression of the epidermal growth factor (EGF) system in invasive bladder cancer and to assess its prognostic value.

METHODS

This immunohistochemical study was performed using fresh frozen tumor samples and a panel of monoclonal antibodies on a series of 43 invasive bladder cancers treated by cystectomy.

RESULTS

EGF was detected in 45% of the tumors and did not correlate with survival from bladder cancer. Transforming growth factor alpha (TGF alpha) was expressed by 60% of the tumors and correlated strongly with death from bladder cancer. Epidermal growth factor receptor (EGF-R) expression was seen in 86% of cases and had no prognostic significance. c-erbB2 was expressed in 50% of cases and was inversely related to a poor prognosis. When EGF and TGF alpha were both expressed, there was little or no expression of c-erbB2.

CONCLUSION

The accumulation of several growth factors and the relevant receptor are necessary for the progression of invasive bladder cancers. They could be used as indicators of tumor aggressiveness.

Patterns of epidermal growth factor receptor amplification in malignant gliomas

Amplification of the gene for epidermal growth factor receptor (EGFR) is a common finding in malignant gliomas. We found that 18 of 29 grade 3 and grade 4 gliomas had EGFR amplification when assayed using fluorescence in situ hybridization. The amplification pattern suggests that the amplicon is contained within double minute chromosomes in most cases. EGFR copy number can differ by 20-fold in amplified cells within a single case. Polysomy 7 occurs frequently in both EGFR-amplified and -unamplified cells. More than one-third of the cases had < or = 10 percent of cells with amplified EGFR, and it is likely that these cases would not have been identified by methods that do not examine DNA on a cell by cell basis.

Espressione di oncogeni di proliferazione e morte cellulare nel carcinoma superficiale della vescica: Expression of oncogenes in relation to cell proliferation and death in superficial bladder carcinoma

Although superficial bladder cancer may be considered “benign”, it is still today a many-sided neoplasm with a prognosis that cannot be well-defined with known traditional parameters. Proliferation indices Ki67 and AgNOR associated with the expression of some oncogenes (p53, Rb, c-myc, BCL2, c-erbB-2) in relation to traditional parameters could help in the prognosis definition of individual patients. 111 patients with superficial bladder cancer were studied for this purpose, relating the grade, stage, follow-up and morphotype to the proliferation indices. Significant correlations were found with AgNOR, but only for grade with Ki67. The study of the oncoproteins and their different expression showed that those alterations typical of infiltration are already present in the superficial forms, with a significant correlation between oncogenic alterations and grade and stage of disease (p53, Rb) on the one hand, and above all of disease-free interval and progression (c-erbB-2) on the other. Lastly, assessment of the oncoproteins c-myc and BCL2, oncogenes connected with the programmed cell death mechanism (apoptosis), showed important correlations with the neoplastic progression of disease in relation to the p53 expression and proliferative activity.