Objective: To investigate the biological characteristics of human colorectal cancer stem-like cells and their relationship with autophagy. 
Methods: HCT116 sphere cells (colorectal cancer stem-like cells) were dissociated from the human colorectal cancer HCT116 cells by culture with serum-free medium. The proliferative and self-renewal abilities as well as the invasion and migration abilities of HCT116 cells and HCT116 sphere cells were detected by colony formation assay, sphere-forming assay, and Transwell assay respectively. In addition, the fluorescence expressions of the autophagy marker LC3B in the two types of cells were detected by immunofluorescence assay, and the mRNA and protein expressions of LC3B and autophagy-associated genes ATG5 and ATG7 in the two types of cells were determined by RT-PCR and Western blot respectively.
Results: The colony formation and sphere formation abilities as well as invasion and migration abilities of HCT116 sphere cells were significantly stronger than those in HCT116 cells (all P<0.05). The fluorescence intensity of LC3B in HCT116 sphere cells was significantly enhanced compared with HCT116 cells (P<0.05). The mRNA and protein expressions of LC3B, ATG5 and ATG7 in HCT116 sphere cells were significantly higher than those in HCT116 cells (all P<0.05).
Conclusion: Colorectal cancer stem-like cells have enhanced self-renewal and proliferative abilities as well as increased invasion and migration abilities in vitro compared to colorectal cancer cells, and these biological characteristics may be closely related to their autophagic activities.