Objective: To study the effect of hypoxia-inducible factor-1α (HIF-1α) on human gastric cancer cells apoptosis in simulated CO2 pneumoperitoneum environment.
Methods: Applied 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.
Results: In 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).
Conclusions: The 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.