Study on the inhibition of hyperthermic CO₂ pneumoperitoneum on the proliferation and migration of colon cancer cells and its mechanism.

The present study explored the inhibitory effect of hyperthermic CO2 pneumoperitoneum on the proliferation and migration of colon cancer cells, and its mechanism. Colon cancer cell line SW-480 was sealed into a urine collection bag to simulate pneumoperitoneum with 100% CO2 under a pressure of 14 mmHg. The growth and morphology of cells were observed under a microscope, the inhibition on cell proliferation was measured using WST-8 test, cell apoptosis and the cell cycle were monitored using fluorescence-activated cell sorting analysis, the migration of cells was tested using the scratch assay, and the expression of HSP-70, caspase-3, hypoxia-inducible factor-1α (HIF-1α) and matrix metalloproteinase-9 (MMP-9) proteins and genes was investigated using western blotting and reverse transcription polymerase chain reaction. Compared with the control group, there was no significant difference in the CO2 group (P>0.05), while the apoptosis and necrosis rates in the hyperthermo-CO2 group was significantly increased (P<0.05). Compared with the control group, the number of cells at G0/G1 phase significantly increased and the number of cells at S phase significantly decreased in the hyperthermo-CO2 group (P<0.05), indicating that hyperthermo-CO2 could arrest the cell cycle. It was suggested by the results of the scratch assay that cell migration ability enhanced in the CO2 group, but decreased in the hyperthermo-CO2 group compared with the control. CO2 pneumoperitoneum promoted cell migration by upregulating HIF-1α and MMP-9 expression. However, the CO2 pneumoperitoneum with hyperthermia enhanced apoptosis and inhibited migration by upregulating the expression of HSP-70, HIF-1α and caspase-3, but downregulating the expression of MMP-9.