Figure 5

Cervical cancer-initiating cells (CCICs) are more resistant to X-ray treatment. A, DNA repair double-strand breaks (DSB) genes differentially expressed in HeLa CCICs. B, as in A but SiHa CICs. C, Reactive oxygen species (ROS) metabolism genes overrepresented in HeLa and SiHa CCICs-enriched spheroids compared with monolayer counterparts. D, Cell survival curves for CCICs-enriched spheroid and monolayer cells. For x-ray treatment, cells were dissociated and irradiated in suspension with 0, 2, 4, 6, 8, and 10 Gy with a linear accelerator Clinac 2100C operating at 200 cGy/min and 6MV. Cells were then seeded in six-well dishes at an appropriate number with DMEM and noble agar (0.3%) for clonogenic survival assay. Twenty one days after irradiation colonies were fixed and stained. Colonies comprising >50 cells were counted for each dose point. To determine surviving fractions (SFs) counts were normalized using the plating efficiency (PE) of the unirradiated corresponding control. Error bars represent standard deviation (SD). Data shown are representative of three independent experiments; S: CCICs-enriched spheroid cells