Fig. 1

DNA repair is associated with the biogenesis of cancer stem cells. A Sorting of gastric cancer stem cell-like cells (GCSCs) from MKN-45 cell line. The fluorescence-activated cell sorting was performed based on the detection of ALDH1 activity using the ALDH1 fluorescent substrate BODIPY-aminoacate (BAAA). The ALDH1-positive cells were gastric cancer stem cell-like cells (P4 region) and ALDH1-negative cells were gastric cancer non-stem cells (P3 region). B Expression of stemness genes in ALDH1-positive cells. The gene expressions were examined with quantitative real-time PCR (**p < 0.01). C Expressions of stemness genes in ALDH1-positive cells and ALDH1-negative cells using Western blot. β-tubulin was used as a control. D Upregulation of NME2 in the cancerous tissues of gastric cancer patients. The gene expression of NME2 in the cancerous tissues of gastric cancer patients and healthy donors was analyzed with the Cancer Genome Atlas (TCGA) database. E Identification of proteins interacted with the promoter of transcription factor NME2 gene. Nuclear proteins extracted from gastric cancer stem cell-like cells (MKN-45) were incubated with biotin-labeled dsDNA of NME2 promoter and streptavidin-agarose beads. An intragenic double-stranded DNA coupled to Streptavidin-agarose beads alone was used as a control. The proteins bound to NME2 promoter were separated by SDS-PAGE with Coomassie staining and then identified by mass spectrometry. Arrows indicated the identified proteins interacted with the NME2 promoter. M, protein marker. F Western blot analysis of the proteins bound to the promoter of NME2. The proteins of the pulldown eluates using the promoter of NME2 were subjected to Western blot analysis. Streptavidin-agarose beads coupled with an intragenic double-stranded DNA served as a control