Background: To investigate thymidine kinase 1(TK-1) and Ki67 expression levels of human colorectal carcinoma cells line SW480 after exposure to a simulated laparoscopic carbon dioxide (CO2) pneumoperitoneum environment at different pressures and lengths of exposure time.
Methods: The effects of the simulated laparoscopic CO2 pneumoperitoneum environment at different CO2 pressures (6, 9, 12, and 15 mmHg) and exposure times (2 and 4 h) on TK-1 and Ki67 of SW480 cells were assessed by flow cytometry and reverse transcription (RT-PCR). Cells cultured in a standard environment were used as the control group (at 37 °C, 5% CO2).
Results: In this study, TK-1 and Ki67 in SW480 cells tended to decrease with the increase of CO2 pressure and exposure time. Significantly lower expression levels were observed at 0 and 24 h of culture after exposure to both at 12 and 15 mmHg, as compared with the control group at 6 and 9 mmHg (p < 0.05). The expression of TK-1 and Ki67 levels increased up to a plateau of the control group after 48 and 72 h (p > 0.05). With the CO2 pneumoperitoneum exposure time prolonging, the expression of TK-1 and Ki67 levels in 12 or 15 mmHg was lower than in 2 h (p < 0.05). In the same exposure time, the transcription level of TK-1 and Ki67 decreased significantly in 12 and 15 mmHg CO2 pneumoperitoneum groups (p < 0.05) and returned to the basal level of control group after being cultivated for 48 h (p > 0.05). In the same pressure, the difference of TK-1 mRNA between the groups of 2 and 4 h was also significant.
Conclusion: The expression levels of TK-1 and Ki67 were suppressed temporarily after the continuous CO2 insufflation in higher pressure (at 12 and 15 mmHg). The higher the pressure of CO2 insufflation, the more the inhibiting effects of TK-1 and Ki67 will be. The longer the time of CO2 insufflation, the more significantly their expression decreased.