Fig. 1
Hyperthermia significantly suppressed the proliferation and stemness of NPC cells. A, B CCK-8 assay A and colony formation assay B were performed in indicated NPC cells treated with hyperthermia at 42 °C or 44 °C for 30 min. C-E The xenograft subcutaneous tumor formation of hyperthermia-treated CNE2 cells in nude mice. CNE2 cells in vitro treated with hyperthermia at 42 °C or 44 °C for 30 min were injected subcutaneously into nude mice (n = 6). C Representative images of stripped xenograft tumors formed by CNE2 cells at the end of experiment. D The growth curve of tumor volumes within 20 days. E Tumor weight. F, G qRT-PCR F and Western blot G were employed to detect stemness-related gene expression in indicated NPC cells treated with hyperthermia at 42 °C for 30 min. H, I Flow cytometry analysis of the percentages of side population (SP) cells in indicated NPC cells treated with hyperthermia at 42 °C or 44 °C for 30 min. J, K Tumor sphere formation assay was used to detect the self-renewal ability of NPC cells treated with hyperthermia at 42 °C or 44 °C for 30 min. For tumor sphere formation assay, the indicated NPC cells (1 × 103/well) treated with hyperthermia at 42 °C or 44 °C for 30 min were grown in serum-free DMEM-F12 supplemented with 10 μg/L bFGF, 20 μg/L EGF and 2% B27 in ultra-low adhesion plates. Two weeks later, spheres were counted by an inverted microscope, and images were acquired. Sphere size and density are shown in the left panels J, and the number of spheres is shown in the right panels K