Agata Sasor, Malgorzata Wagrowska-Danilewicz, Marian Danilewicz

Ki-67 Antigen and P53 Protein Expression in Benign and Malignant Prostatic Lesions. Immunohistochemical Quantitative Study

Chair and Department of Pathomorphology, Medical University, Lodz

Abstract

Ki-67 and P53 expression were studied using immunohistochemistry on tissue samples obtained during transurethral electroresection or needle biopsy in 62 patients with prostatic lesions: group 1 (n=15) - benign prostatic hyperplasia (BPH), group 2 (n=10) - high-grade prostatic intraepithelial neoplasia (PIN 3), group 3 (n=10) - low- grade prostatic carcinoma (PC, Gleason score 2 - 4), group 4 (n=12) intermediate-grade prostatic carcinoma (PC, Gleason score 5 - 7) and group 5 (n=15) high-grade prostatic carcinoma (PC, Gleason score 8 - 10). Moreover, in the groups examined the associations between expression of Ki-67 and P53 were analysed. Paraffin-embedded tissue samples were immunostained with monoclonal antibody anti-P53 and polyclonal antibody anti-Ki-67 using avidin-biotin-peroxidase method. Our study revealed lack of Ki-67 and P53 immunoreactivity in BPH. Only 3 out of 10 high-grade PIN exhibited Ki- 67 positivity, but there was no immunopositivity of P53 protein in this group. Although immunopositivity of Ki-67 increased with the histological grade of prostatic cancer, the differences in Ki-67 expression between intermediate and high-grade cancer did not reach statistical significance. A similar level of Ki-67 reactivity in intermediate- differentiated and poorly-differentiated prostate cancer suggests a similar biology of these cancers. P53 protein positivity was noted in 62.2% cases of prostate cancer. Moreover, the highest level of P53 accumulation in intermediate-grade carcinomas may predict the aggressive progression and risk of metastases in these cases. No significant differences in P53 immunopositivity between low-grade and high-grade PC were noted. Interestingly, only in low-grade PC there was a significant positive correlation between expression of Ki-67 and P53 protein.

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