OBJECTIVETo study the effect of hypoxia-inducible factor-1α (HIF-1α) on human gastric cancer cells apoptosis in simulated CO2 pneumoperitoneum environment.

METHODSApplied closed box to simulated CO2 pneumoperitoneum environment under the pressure of 0, 5, 10 and 15 mm Hg (1 mm Hg = 0.133 kPa). Compared HIF-1α mRNA and protein expression of MKN-45 cells before and after silencing HIF-1α by RT-PCR and Western blot. Study the changes of bcl-2/bax expression in MKN-45 cells before and after silencing HIF-1α by immunohistochemistry. The apoptosis ratio of MKN-45 was measured by using Annexin V-FITC/PI double labelled staining.

RESULTSIn 15 mm Hg group, HIF-1α mRNA and protein expression of MKN-45 cells (1.48 ± 0.22, 1.34 ± 0.09) and HIF-1α protein expression in 10 mm Hg group (1.25 ± 0.10) were significantly higher than those in control group (0.55 ± 0.17, 0.83 ± 0.04) (P < 0.05). But there was no significant differences among 0, 5, 10 mm Hg group and control group in HIF-1α mRNA (P > 0.05); and no obvious difference was found among 0, 5 mm Hg group and the control group in HIF-1α protein expression (P > 0.05). In 15 mm Hg CO2 pressure, bcl-2/bax expression (0.78 ± 0.05) was obviously lower than that in the control group (1.43 ± 0.15) (P < 0.05) and the apoptosis ratio (11.70 ± 0.12) was significantly higher than the control group (0.22 ± 0.07) (P < 0.01) before silencing HIF-1α. But once HIF-1α was silenced, HIF-1α mRNA (0.52 ± 0.11), HIF-1α protein expression (0.92 ± 0.02), bcl-2/bax ratio (1.57 ± 0.04) and apoptosis ratio (0.45 ± 0.11) in MKN-45 were not significantly different between 15 mm Hg group and the control group (P > 0.05).

CONCLUSIONSThe apoptosis ratios of MKN-45 under 0, 5, 10 mm Hg CO2 pneumoperitoneum are comparable with that in the control group before the silencing of HIF-1α. The apoptosis ratio of MKN-45 is increased under 15 mm Hg CO2 pneumoperitoneum environment and HIF-1α may be one of the important factor to improve the apoptosis of human gastric cancer cell.