p53 immunoreactivity correlates with Ki-67 and bcl-2 expression in renal cell carcinoma

This study assessed the relation of proliferation, inhibition of apoptosis, and the p53 tumor suppressor protein expression in clear renal cell carcinoma (RCC). Archival pathological specimens from 43 patients treated for RCC were obtained. Median follow-up for the patients was 52 months (range 2.5 months to 178 months). Immunostaining of paraffin tissue sections was carried out for four different markers: a) Ki-67, a marker for cellular proliferation; b) p53/DO7, c) p53/pAb240, antibodies for the p53 protein; and d) bcl-2, a marker for inhibition of apoptosis (programmed cell death). One thousand cells were counted per slide at 400x magnification. Staining of >/=10% of cells was considered positive and <10% negative. Fisher exact contingency tables were used for correlation between markers, tumor grade and stage. A significant correlation was found between Ki-67 and p53 immunoreactivity samples, P=0.0001. Interestingly, a significant association was found if Ki-67 and bcl-2 scores were combined and correlated with p53, P=0.009. Results showed no correlation between any of the immunohistochemical markers and grade or stage. In addition, Kaplan-Meier survival curves demonstrated no significant difference between patients' tumors that was scored immunoreactive negative vs. positive for Ki-67, p53, or bcl-2. This study indicates that p53 expression correlates with proliferation, and inhibition of programmed cell death in RCC.