EXPRESSION OF THE APOPTOSIS SUPPRESSING BCL-2 PROTEIN IN TRANSITIONAL-CELL BLADDER-TUMORS

The expression of bcl-2 protein was studied by immunohistochemistry us ing a monoclonal antibody in 158 cases of transitional cell bladder tu mours. The bcl-2 protein was expressed in basal cells in normal transi tional epithelium and 68% of the transitional cell tumours showed bcl- 2 positivity in the basal cells. The expression of bcl-2 in basal cell s was positively correlated to over-expression of epidermal growth fac tor receptor in tumour cells. The expression of bcl-2 in non-basal cel ls was weak in 20% and strong in an additional 13% of tumours. The exp ression of bcl-2 in non-basal cells was positively correlated to T-cat egory, M-category, grade, papillary status, DNA ploidy, S phase fracti on, mitotic index, nuclear area and oner-expression of epidermal growt h factor receptor. Recurrence-free interval of Ta-Tl tumours was relat ed to bcl-2 positivity in non-basal cells. Tumours with bcl-2 positive non-basal cells had an unfavourable prognosis but, in multivariate an alysis, expression of bcl-2 had no independent prognostic value.