OBJECTIVETo investigate the expression of clusterin protein in bladder transitional cell carcinoma (BTCC) and it's association with tumor cell proliferation and apoptosis.

METHODSA tissue microarray (TMA) containing 87 informative cases of BTCCs was constructed firstly. The methods of immunohistochemistry and terminal deoxynucleotidyl transferase-mediated nick end-labeling were then used to examine the expression of clusterin and Ki-67 protein and the status of cell apoptosis in BTCC, respectively, and the correlations between different markers and the clusterin expression associated with patients' clinico-pathological features were evaluated.

RESULTSIn TMA of 87 BTCCs, 37 (43%) cases were observed overexpression of clusterin. A significant association of clusterin expression with BTCC's pathological grade, as well as with tumors clinical stage was observed (P < 0.01), where the frequency of overexpression of clusterin in poor differentiated BTCCs (G(3), 71%) and tumors in more advanced stage (T(2-4), 62%) was significantly higher than that in well differentiated BTCCs (G(1-2), 29%) and tumors in early stage (T(a-1), 28%). In addition, a significant correlation between clusterin expression and tumors apoptotic index (AI) was evaluated (P < 0.01), in which 57% of BTCCs with overexpression of clusterin were observed a lower AI, while 72% of tumors with normal expression of this protein showed a higher AI, but no correlation between clusterin and Ki-67 expression.

CONCLUSIONSThe overexpression of clusterin is associated positively with BTCC's malignant clinical phenotypes including tumor's differentiation and invasive depth, and it is correlated inversely with AI of tumor cells.