Quantitative Immunocytochemical Assays of Topoisomerase II in Lung Adenocarcinoma Cell Lines : Correlation to topoisomerase IIα content and topoisomerase II catalytic activity

Abstract

The examination of topoisomerase IIα content by Western blot analysis or topoisomerase II catalytic activity by decatenation of kDNA requires a large number of cells, but it is difficult to collect sufficient cells for these biochemical analyses from lung cancer patients by transbronchial brushing or aspiration. In this study, we explored the relationship between these biochemical analyses and topoisomerase II immunostaining in cytospin preparations of three lung adenocarcinoma cell lines. The levels of topoisomerase IIα content were about 8.4 for A549, 2.9 for PC-3 and 1 for RERF-LC-MS, and the levels of topoisomerase II catalytic activity were about 4, 2, and 1, respectively. The percentages of strongly positive cells for topoisomerase II immunostaining were 60.9% for A549, 33.3% for PC-3, and 14.3% for RERF-LC-MS, and these were compatible with the levels of topoisomerase IIα content or topoismerase II catalytic activity. Our results indicate that topoisomerase II immunostaining can be utilized in place of biochemical analysis.