[1018] Comparison of p40 (ΔNp63) and p63 Expression in Prostate Tissues as Markers of Benign Glands

Verena Sailer, Carsten Stephan, Nicolas Wernert, Sven Perner, Glen Kristiansen. University of Bonn, Bonn, Germany; Charite-Universitätsmedizin Berlin, Berlin, Germany

Background: The diagnosis of prostate carcinoma can be challenging, especially in small needle core biopsies. Immunohistochemistry provides added information regarding the loss of basal cells, which is a key feature of malignancy in the prostate gland. p63, a homolog of the p53 suppressor gene, is one of the standard markers for basal cells of the prostatic gland. Recently, it has been suggested that the p63 isoform p40 might be more specific as a basal cell marker. Here we compare the staining characteristics of p63 and p40 in normal and malignant prostate tissue.
Design: A prostatectomy cohort (n=640) in tissue microarray format (with 5 cores per case) was evaluated for p63 (clone 4A4) and for p40 (rabbit polyclonal) immunoreactivity in malignant and benign tissues alike. Immunoreactivity of basal and secretory cells was evaluated in a semiquatitative manner and compared case-wise.
Results: In benign tissues, p40 showed a highly similar immunoreactivity compared to p63. The staining patterns were totally equal 73% of cases, minor differences were detected in 27%. A mild to moderate cytoplasmatic p40 staining in tumour cells occurred in 59% of cancer cases. For the nuclear staining, differences were seen in carcinomas: 1.4 % of carcinomas were p63-positive, whereas p40 labelled only 0.6% of these cases.
Conclusions: p40 can be used as a reliable marker of basal cells in prostate diagnostics and it appears to be more specific with a lower rate of false-positive cancer cases compared to p63. However, the additional cytoplasmic staining makes it a less attractive partner to combine it with Alpha-methyl-Co-racemase (AMACR). This study also highlights that the number of p63-positive prostate carcinomas is probably higher than previously thought.
Category: Genitourinary (including renal tumors)

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 148, Wednesday Afternoon


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