Abstract: Abstract: Objective To observe the effects of hypoxic microenvironment on the proliferation, invasion and autophagy of colon cancer cells and investigate the relationship between survival and autophagy of colon cancer cells under hypoxic conditions. Methods: CD 133+ cancer stem cells (cancer stem cells, CSCs) were purified using MACS (magnetic activated cell-sorting system) CD 133+ cell isolation kit. The invasion of colon cells was measured by Boyden Chamber. The ultrastructure was observed using transmission electron microscope (TEM). The autophagy vesicles were detected by monodansylcadaverin (MDC) fluorescence. The relationship between autophagy and cell survival was analyzed using flow cytometry together with trypan blue staining. Results In Boyden Chamber, the amount of SW480 moving into the second floor was increased under the hypoxic microenvironment. In experimental groups that were exposed to hypoxic conditions, the MDC fluorescence intensity of SW480 cells decreased from 20.53±0.64 to 17.00±0.20, while that of CD133+ CSCs increased from 19.89±0.58 to 33.13±1.95 (P<0.05). The trypan blue staining showed that under hypoxic conditions, the viability of SW480 cells decreased significantly over time (P<0.05), while that of CD133+ cells had no significant changes. Conclusion: For SW480 cells, the invasion could be enhanced under the hypoxic microenvironment, with both the level of autophagy and viability decreased. For CD133+ cells, the occurrence of autophagy increased under the hypoxic environment, with the viability basically unchanged.

Key words: hypoxia, autophagy, colon cells, CD133+