Downregulation of Sox2 and Oct3/4 expression inhibits sphere formation induced by radiation treatment.

<p><b>A and B</b> HepG2 cells and Huh7 cells transfected with aiRNA targeting GFP, Sox2 or Oct4 were exposed after 24 hours to 0, 2 or 4 Gy of gamma radiation and then plated onto 96-well ultra low attachment plates at 500 cells/well in stem cell media. Sphere numbers for each knockdown group and radiation treatment were recorded on day 7 of culture in stem cell media. Silencing of Sox2 or Oct4 significantly reduced sphere formation in HepG2 and Huh7 cells treated with low doses of gamma radiation compared to non-irradiated cells, or cells transfected with aiRNA against GFP. Results are presented as mean±SEM of four independent experiments, n = 4. *p<0.05, **p<0.01, versus GFP-transfected cells or non-irradiated control cells (0 Gy).