Fig. 3

Casticin inhibits the formation of tumour spheres derived from NPC cells. a S18, CNE2, C666-1 cells were induced to generate tumour spheres and were treated with 20 µM casticin for 72 h. b The number and diameter of spheres of different groups are shown in the right panels. All data are presented as the mean ± standard deviation. *p < 0.05 versus control, and **p < 0.01 versus control. c Western blotting showing the expression levels of stem cell marker proteins, such as NANOG, OCT4, and SOX2 which were examined in tumour spheres (SP) and compared with their parental cells (PC). All data are presented as the mean ± standard deviation. *p < 0.05 versus PC. d The levels of expression of NANOG, SOX2, and OCT4 in C666-1 cells were examined after treatment with a gradient of casticin concentrations (0, 4, 8 or 16 µM) for 24 h. All data are presented as the mean ± standard deviation. *p < 0.05 versus 0 µM, and ^&p < 0.05 versus 8 µM