Quantitative analysis of topoisomerase II alpha and evaluation of its effects on cell proliferation and apoptosis in glioblastoma cancer stem cells

DNA topoisomerase II alpha (Topo-II alpha) is an essential nuclear enzyme with its up-regulation demonstrated in different tumors. This study is to evaluate the expression of Topo-II alpha in glioblastoma cancer stem cells (CSCs) and its effects on cell proliferation and apoptosis. We observed the expression differences of Topo-II alpha gene transcript in CSCs and non-CSCs in glioblastoma cell line U87 by quantitative real-time PCR and western blot; we silenced Topo-II alpha expression in U87 CSCs using Topo-II alpha-specific siRNA to investigate the role of Topo-II alpha in cell proliferation, cell cycle, and apoptosis. We found higher expression of Topo-II alpha in CSCs than in non-CSCs. After using Topo-II alpha-specific siRNA to silence the expression of Topo-II alpha gene, we observed decreasing cell proliferation, cell cycle arrest, and induction of apoptosis in CSCs, which suggest that Topo-II alpha contributes to both cell proliferation and/or cell survival. Topo-II alpha may be a novel marker of cell proliferation and/or survival factor in glioblastoma CSCs. It may be a potential target that will open up new opportunities to develop therapeutic strategies for gliomas. (C) 2012 Elsevier Ireland Ltd. All rights reserved.