Effects of poly(L-lysine)-modified Fe3O4 nanoparticles on endogenous reactive oxygen species in cancer stem cells

Intracellular reactive oxygen species (ROS) have been extensively shown to play an important role in the regulation of cell proliferation and cell cycle progression. The effects of endogenous ROS on the proliferation and differentiation of cancer stem cells (CSCs) have received increasing attention because of the unique properties of these cells that allow them to drive tumor growth and evade conventional cancer therapies. In this study, poly(L-Lysine) (PLL)-modified Fe3O4 nanoparticles were synthesized to label CSCs derived from U251 glioblastoma multiform. A featured peroxidase-like activity within PLL-modified Fe3O4 nanoparticles that could greatly reduce intracellular H2O2 activity was identified. We also found that PLL-modified Fe3O4 nanoparticles could accelerate the progression of CSC cell cycle, probably due to the impaired activity of endogenous ROS in CSCs. These results show that growth and proliferation of CSCs could be promoted by Fe3O4 nanocarriers in an ROS-dependent manner, and Fe3O4 nanocarriers may be suitable for certain tumor therapies as a drug delivery system. (C) 2012 Elsevier Ltd. All rights reserved.