GAS5 inhibits cell proliferation and sphere formation in CSCs derived from HCT116 cells. (A) After introduction of siRNA to target GAS5, GAS5 mRNA expression was measured by reverse transcription-quantitative PCR. (B) Western blotting was performed to measure Oct4 and Sox2 protein expression levels after GAS5 knockdown. (C) Serial replating assay was performed after GAS5 knockdown. Magnification, ×40. (D) Cell viability was measured from day 1–4 after GAS5 knockdown. (E) Flow cytometry was performed after propidium iodide staining to determine the proportion of cells in cell cycle phases after GAS5 knockdown. After GAS5 knockdown, (F) tumor formation in soft agar and (G) Transwell assays were performed. *P<0.05 vs. siNC group. CSCs, cancer stem-like cells; GAS5, growth-arrest-specific transcript 5; NC, negative control; OD, optical density; siRNA, small interfering RNA.