Nuclear Expression of PTEN in Endometrial Carcinoma
Bojana Djordjevic, Russell Broaddus. University of Ottawa, Ottawa, ON, Canada; MD Anderson Cancer Center, Houston, TX
Background: PTEN protein is a tumor suppressor which negatively regulates the PI3K–AKT signaling pathway via its cytoplasmic phosphatase function, and its loss is implicated in the pathogenesis of endometrial carcinoma (EC). Nuclear presence of the PTEN protein was recently found in cell lines to also have tumor suppressive activity via a mechanism independent of phosphatase activity. The purpose of this study was to characterize the nuclear vs. cytoplasmic expression of PTEN in a set of EC in which the PTEN mutation status is known.
Design: 154 EC cases consisting of 100 endometrioid and 54 non-endometrioid carcinomas were subjected to PTEN IHC analysis as well as to full-length PTEN gene sequencing to detect mutations. The PTEN antibody was previously validated on cancer cell lines. Cytoplasmic IHC staining was scored as positive (Cyto-pos:>90% of tumor with diffuse cytoplasmic staining), negative (Cyto-neg: 0% of tumor cells staining) and heterogeneous (Cyto-het: distinct positive and negative foci). Nuclear IHC staining was scored as positive (Nuclear-pos: >10% of tumor cells) or negative (Nuclear-neg: ≤ 10%).
|Cyto-neg, Nuclear-neg||Cyto-pos or het, Nuclear-neg||Cyto-pos or het, Nuclear-pos|
|PTEN wild type||21||14||14|
|PTEN wild type||6||17||16|