Expression of the apoptosis suppressing bcl-2 protein in transitional cell bladder tumours

The expression of bcl-2 protein was studied by immunohistochemistry using a monoclonal antibody in 158 cases of transitional cell bladder tumours. The bcl-2 protein was expressed in basal cells in normal transitional epithelium and 68% of the transitional cell tumours showed bcl-2 positivity in the basal cells. The expression of bcl-2 in basal cells was positively correlated to over-expression of epidermal growth factor receptor in tumour cells. The expression of bcl-2 in non-basal cells was weak in 20% and strong in an additional 13% of tumours. The expression of bcl-2 in non-basal cells was positively correlated to T-category, M-category, grade, papillary status, DNA ploidy, S phase fraction, mitotic index, nuclear area and oner-expression of epidermal growth factor receptor. Recurrence-free interval of Ta-Tl tumours was related to bcl-2 positivity in non-basal cells. Tumours with bcl-2 positive non-basal cells had an unfavourable prognosis but, in multivariate analysis, expression of bcl-2 had no independent prognostic value.