Prognostic significance of Ape1/Ref-1 subcellular localization in non-small cell lung carcinomas

PURPOSE: To evaluate the prognostic value of the DNA repair/redox-protein Ape1/ref-1 in a retrospective series of consecutive non-small cell lung carcinomas (NSCLC). PATIENTS AND METHODS: Sections from 91 radically resected NSCLC were analyzed for immunohistochemical expression of Ape1/ref-1. For each case 1,000 tumor cells were evaluated to detect nuclear and cytoplasmic reactivity scored as a percentage of positive cells. With respect to sub-cellular localization and percentage of immunoreactive cells, each tumor was classified as "cytoplasmic" or "non cytoplasmic". The survival rate according to Ape1/ref-1 sub-cellular localization was calculated. RESULTS: The main pattern of Ape1/ref-1 expression was nuclear. No significant difference was observed in Ape1/ref-1 pattern according to histotype (squamous vs adenocarcinoma). Among adenocarcinomas, a cytoplasmic expression of Ape1/ref-1 was significantly associated with poor survival rate in univariate (p=0.01) and multivariate (p=0.07) analyses. In addition, a cytoplasmic expression of the DNA repair protein was also predictive of worse prognosis (log-rank test, p=0.02) in cases with lymph node involvement, regardless of histotype. CONCLUSION: The results suggest a potential role of Ape1/ref-1 sub-cellular localization as a prognostic indicator in patients with NSCLC. In particular, cytoplasmic localization of the protein seems to confer a poor outcome in subgroups of patients with nodal involvement or adenocarcinoma histotype.