Widespread expression of prostate apoptosis response-4 in nasopharyngeal carcinoma

Background. Prostate apoptosis response‐4 (Par‐4) augments apoptosis in various tumors, either during apoptotic insult or by ectopic overexpression. However, investigation of Par‐4 expression in nasopharyngeal carcinoma (NPC) is lacking. Methods. Specimens from patients with NPC, hypopharyngeal carcinoma (HPC), or oral cavity cancer were examined for Par‐4 expression using immunohistochemistry. NPC cell proliferation and apoptosis were analyzed using immunohistochemical staining for Ki67, B‐cell lymphoma 2 (Bcl‐2), and in situ terminal deoxyribonucleotidyl transferase (TdT)–mediated biotin‐16‐dUTP nick end‐labeling (TUNEL) assay, respectively. Results. Par‐4 was ubiquitously expressed in NPC biopsies (96.2%, 25/26) and was significantly higher than in HPC (47.6%, 50/105, p < .0001) and oral cavity cancers (38.7%, 12/31, p < .0001). Remarkably, apoptosis of NPC cells was absent and Par‐4 expression was associated with obvious expression of Bcl‐2 and Ki67 in all patients tested with NPC. Conclusions. Immunohistochemistry results showed widespread expression of Par‐4 in NPC and revealed sustainable proliferation of NPC cells regardless of Par‐4 expression.© 2009 Wiley Periodicals, Inc. Head Neck, 2010