Increased p53 immunoreactivity in proliferative inflammatory atrophy of prostate is related to focal acute inflammation

Proliferative inflammatory atrophy (PIA) of prostate has been proposed as a precursor lesion of prostate cancer. The aim of the current study was to evaluate the expression of p53 protein in PIA lesions and to investigate the relationship between p53 staining and Ki-67, glutathione S-transferase-p (GSTP1) and cyclooxygenase-2 (COX-2) immunohistochemical expression. The results revealed that p53 nuclear immunostaining appeared in PIA lesions in 2.1 +/- 3.4% (mean +/- SD) of the basal and 0.9 +/- 2.3% of the luminal epithelial cells. Both these values were significantly higher than those in normal-appearing acini (p<0.0001). Increased p53 expression in luminal cells was related to focal infiltration of polymorphonuclear leucocytes. A positive correlation between p53 expression and Ki-67 was found in COX-2-positive PIA lesions (r = 0.610, p<0.0001). Half of the p53-positive epithelial cells expressed diffuse GSTP1 immunostaining in the same lesions. The present study demonstrates an increased p53 expression in PIA lesions, and inflammation, especially acute inflammation, may play a role in the induction of p53 over-expression, particularly as cells in PIA lesions are known to have a reduced defence against DNA damage.