Loss of PTEN expression in paraffin-embedded primary prostate cancer correlates with high gleason score and advanced stage

The tumor suppressor gene PTEN/MMAC-1/TEP-1 (referred to hereafter as PTEN) maps to chromosome 10q23 and encodes a dual specificity phosphatase, The P TEN protein negatively regulates cell migration and cell survival and induc es a G(1) cell cycle black via negative regulation of the phosphatidylinosi tol 3'-kinase/protein kinase B/Akt signaling pathway, PTEN is frequently mu tated or deleted in both prostate cancer cell lines and primary prostate ca ncers. A marine polyclonal antiserum was raised against a glutathione S-tra nsferase fusion polypeptide of the COOH terminus of PTEN, Archival paraffin tissue sections from 109 cases of resected prostate cancer were immunostai ned with the antiserum, using DU145 and PC-3 cells as positive and negative controls, respectively. PTEN expression was seen in the secretory cells, C ases were considered positive when granular cytoplasmic staining was seen i n all tumor cells, mixed when areas of both positive and negative tumor cel l clones were seen, and negative when adjacent benign prostate tissue but n ot tumor tissue shelved positive staining, Seventeen cases (15.6%) of prost ate cancer were positive, 70 cases (64.2%) were mixed, and 22 cases (20.2%) were negative. Total absence of PTEN expression correlated with the Gleaso n score (P = 0.0081) and correlated more significantly with a Gleason score of 7 or higher (P = 0.0004) and with advanced pathological stage (American Joint Committee on Cancer stages T3b and T4; P = 0.0078). Thus, loss of PT EN protein is correlated with pathological markers of poor prognosis in pro state cancer.