BACKGROUNDThe ability of pneumoperitoneum in laparoscopic surgery to promote proliferation and metastasis of colorectal cancer has become a focus of research in the field of minimally invasive surgery. The aim of this research was to investigate the effect of CO2 pneumoperitoneum under different pressures and exposed times on the expression of chemokine receptors in colorectal carcinoma cells.

METHODSWe constructed an in vitro pneumoperitoneum model. SW480 colon carcinoma cells were exposed to CO2 pneumoperitoneum under different pressures (6, 9, 12, and 15 mmHg) for 1, 2, and 4 hours. These cells were then cultivated under the same conditions as normal SW480 colon carcinoma cells without CO2 pneumoperitoneum (control group), treated at 37°C, and 5% CO2. The expression of the chemokine receptors CXC receptor 4 (CXCR4) and chemokine C receptor 7 (CCR7) was detected by immunocytochemistry and reverse transcriptase polymerase chain reaction after being cultivated for 0, 24, 48, and 72 hours.

RESULTSImmunocytochemistry showed that CXCR4 expression in SW480 cells was significantly decreased in the 6, 9, 12, and 15 mmHg CO2 pneumoperitoneum-treated groups for the same exposure times compared with controls (P < 0.05). CCR7 expression in SW480 cells was significantly decreased in the 12 and 15 mmHg CO2 pneumoperitoneum-treated groups compared with controls (P < 0.05). CXCR4 and CCR7 expression increased up to the level of the control group after 24 and 48 hours (P > 0.05). If the CO2 pneumoperitoneum pressure increased, CXCR4 and CCR7 expression decreased at all exposure times. If the CO2 pneumoperitoneum exposure time prolonged, there were no significant differences in CXCR4 and CCR7 expression under the same pressure. Under all exposure times, CXCR4 and CCR7 mRNA expression was significantly decreased in the 6, 9, 12, and 15 mmHg CO2 pneumoperitoneum-treated groups (P < 0.05) compared with controls, and it increased up to the level of controls after being cultivated for 48 hours (P > 0.05). If the CO2 pneumoperitoneum pressure increased (with all exposure times) and exposure time prolonged (under the same pressure), there were no significant differences in CXCR4 and CCR7 expression.

CONCLUSIONSCXCR4 and CCR7 expression is temporarily affected after continuous CO2 pneumoperitoneum treatment. The high pressure of CO2 pneumoperitoneum plays an important role in suppressing the expression of these chemokine receptors. Different lengths of time of exposure to a CO2 pneumoperitoneum-like environment do not change CXCR4 and CCR7 expression.