GOS2 inhibits the proliferation of K562 cells by interacting with nucleolin in the cytosol

G0/G1 switch gene 2 (GOS2) is a basic protein with ill-defined function that inhibits the proliferation of hematopoietic stem cells. Herein, we show that treatment of 1(562 cells with 5-azacytidine (5-Aza) resulted in a 24-fold increase in GOS2 expression and a reduction in cell growth. Conversely, gene demethylation in the presence of GOS2-specific shRNA restored proliferation, further supporting an inhibitory role for GOS2 in cell proliferation. Elevated levels of GOS2 inhibited the division of 1(562 cells by sequestering the nucleolar phosphoprotein nucleolin in the cytosol. GOS2 inhibited the proliferation of leukemia cells in vivo in xenograft models. Collectively, our data identify a new mechanism that controls proliferation in K562 cells, suggesting a possible tumor suppressor function in leukemia cells. (C) 2013 Elsevier Ltd. All rights reserved.