Geminin expression in small lung adenocarcinomas: implication of prognostic significance

Geminin is an important molecule which plays a role in cell cycle regulation, and this has been considered to be a useful biomarker of cell proliferation. The purpose of this study was to evaluate the pathological and prognostic significance of geminin expression in small lung adenocarcinoma (AC). We performed Western blot analysis of five human lung AC cell lines and immunohistochemistry on 100 surgically resected specimens of lung AC with a diameter less than 3 cm. We counted the number of positively stained tumor cells, and calculated the labeling indices (LIs). Geminin proteins were variably detected in all five cell lines examined on Western blotting. The mean LIs for geminin, Ki-67, and MCM7 were 7.5%, 12.3%, and 18.5%, respectively. The geminin LIs were associated with some clinicopathological profiles including gender, histological grade, subtypes, N-status, p-factor, and tumor stage. A significantly worse prognosis was noted in the higher geminin LIs group than in the lower group (p < 0.01). Multivariate Cox regression analysis also confirmed that geminin LIs was an independent prognostic marker in stage IA lung AC patients. These results suggest that geminin is overexpressed in small lung ACs, and geminin LIs might be a useful prognostic indicator in patients with lung AC.