Expression of the secreted form of clusterin protein in renal cell carcinoma as a predictor of disease extension

Authors


Hideaki Miyake, Department of Urology, Hyogo Medical Center for Adults; 13–70 Kitaohji-cho, Akashi 673–8558, Japan.
e-mail: hideakimiyake@hotmail.com

Abstract

OBJECTIVES

To evaluate the significance of clusterin expression in surgically resected renal cell carcinoma (RCC) specimens.

PATIENTS AND METHODS

Normal kidney and RCC specimens were obtained from 131 patients who had radical surgery. The expression of clusterin protein was analysed by immunohistochemical staining with an antibody recognizing all isoforms of clusterin. Cell proliferative activities and apoptotic features in these specimens were investigated using Ki-67 immunostaining and the terminal deoxynucleotidyl transferase mediated dUTP nick-end labelling assay, respectively. Findings were evaluated in relation to several clinicopathological factors.

RESULTS

There were various levels of clusterin expression in 128 of the 131 RCC specimens, while 37 of 131 normal kidney tissues (28.2%) had no clusterin staining. Clusterin protein was present in the cytoplasm of both normal and cancer cells, but there was no nuclear staining identified in either type of cell. The expression level of clusterin protein in RCC tissues was significantly related to tumour stage and grade, but not to age, gender or histological cell type. Cell proliferative activity in RCC specimens was significantly associated with clusterin expression, while the apoptotic index was inversely related to clusterin expression. Furthermore, recurrence-free survival in patients with strong clusterin expression was significantly lower than that in those with weak expression.

CONCLUSIONS

These findings suggest that the secreted form of clusterin may be involved in the progression of RCC, and that overexpression of clusterin could be a useful prognostic variable after radical surgery in patients with RCC.

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