Effects of CO2 pneumoperitoneum on focal adhesion kinase of gastric cancer MKN-45 cells.

Objective To investigate the effects of CO2 pneumoperitoneum on the expression of focal adhesion kinase (FAK) of gastric cancer MKN-45 cells. Methods CO2 pneumoperitoneum with different pressures was simulated in vitro, and the gastric cancer MKN-45 cells were divided into test and control groups. In the test group, gastric cancer MKN-45 cells were cultured in CO2 pneumoperitoneum with different pressures [5, 10 or 15 mm Hg (1 mm Hg =0.133 kPa)] for 4 hours. The condition of the cells exposed to CO2 pneumoperitoneum with a pressure of 15 mm Hg was observed at 0.5, 2 and 4 hours. Gastric cancer MKN-45 cells in control group were cultured at normal atmospheric pressure. The expression of FAK and phosphorylated FAK (FAK Tyr397) of each group was detected by Western blot. Multiple-group analysis was done by one-way ANOVA, and intergroup comparison was done by LSD test. Results In CO2 pneumoperitoneum with pressures of 5, 10, 15 mm Hg, the expression of FAK was 2.14±0.17, 2.07±0.21 and 2.52±0.26, respectively, and the expression of FAK Tyr397 was 1.82±0.28, 1.93±0.52 and 3.71±0.37, respectively. The expression of FAK and FAK Tyr397 in the control group was 2.43±0.46 and 1.71±0.23, respectively. We found significant differences between the 2 groups (F = 2.171, 26.951, P < 0.01). After gastric cancer MKN-45 cells being treated for 0.5, 2 and 4 hours in CO2 pneumoperitoneum with a pressure of 15 mm Hg, the expression of FAK Tyr397 was 3.41±0.44, 4.12±0.56 and 5.24±0.41 respectively, which is also significantly different (F =116.119, P < 0.01). The expression of FAK Tyr397 was back to 0.72±0.16 1 hour after the release of CO2. Conclusions CO2 pneumoperitoneum with different pressures can not promote the expression of FAK in gastric cancer MKN-45 cells which had been cultured for 4 hours, but can activate FAK through promoting its phosphorylation. The degree of FAK phosphorylation increases with pressure and time, and the activity of FAK decreases to pretreatment level rapidly once pressure is released. Key words: CO2 pneumoperitoneum;  Gastric neoplasms;  MKN-45 cells;  Focal adhesion kinase