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Cell proliferation and apoptosis with BCL-2 expression in renal cell carcinoma
1Department of Urology, Kagawa Medical University, Kagawa, Japan.
Objectives:
To investigate cell proliferation, apoptosis, and bcl-2 immunoreactivity in renal cell carcinoma (RCC).
Methods:
Formalin-fixed and paraffin-embedded tissue blocks from 70 patients with RCC were studied. Cell proliferation activity was detected by Ki-67 immunostaining and the proliferation index (PI) was expressed as a percentage of the Ki-67-positive cells in the tumor cells. Apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), and the apoptotic index (AI) was expressed as a percentage of the TUNEL-positive cells in the tumor cells. Immunoreactivity of bcl-2 was assessed immunohistochemically and coexpression of Ki-67 with bcl-2 was examined by double immunostaining.
Results:
The PI ranged from 5.0% to 44.0% (median 19.23%) and the AI from 0.9% to 3.4% (median 2.13%) in RCC. Statistical analysis revealed close associations between PI and tumor grade and stage, and a significant relationship between AI and the tumor grade of RCC. The expression of bcl-2 was detected in 24 (34.3%) of 70 RCCs. Coexpression of Ki-67 with bcl-2 was noted in 3 of the 24 RCCs with bcl-2 expression. The expression of bcl-2 was not related to PI, AI, or the clinicopathologic factors of RCC.
Conclusions:
Our observations suggest that active cell proliferation may be accompanied by frequent apoptosis and that cell proliferation as reflected by Ki-67 staining may be the most important parameter of cell turnover in RCC.