Effects of C02 pneumoperitoneum on hypoxia inducible factor-1α, vascular endothelial growth factor and E-cadherin expression of renal cell carcinoma cells and the mechanisms

Abstract

Objective To investigate the effects of artificial CO2 pneumoperitoneum on hypoxia inducible factor-1α （ HIF-1α） , vascular endothelial growth factor （VEGF） , E-cadherin expression of renal cell carcinoma cells, and to explore its regulatory mechanisms. Methods Human renal clear cell carcinoma cells （RCC-949） were cultured in artificial CO2 pneumoperitoneum at 21℃, 99% CO2, 1% O2, 15 mm Hg （ 1 mm Hg = 0. 133 kPa） for 1, 2, 4 h, and the mRNA and protein expression of HIF℃ and VEGF and E-cadherin was detected by reverse transcription-polymerase chain reaction （RT-PCR） and Western blotting, respectively. RCC-949 cells cultured in culture fluid containing 10μmol/L chloride cobalt （CoCl2 ） served as positive hypoxia controls. Correlation analyses were performed to investigate their regulatory relationship. Results After culture in artificial CO2 pneumoperitoneum for 1, 2, 4 h, as compared with the control group, HIF-1α protein and mRNA expression levels of RCC-949 cells were increased by 37% , 68% , 158% and 1371% , 1784% , 2374% , and VEGF protein and mRNA expression levels increased by 77% , 103%, 172% and 1582%, 2107% , 2432% , but E-cadherin protein and mRNA expression levels decreased by 17% , 27%, 44% and 43% , 71%, 95% respectively, and there were significant differences （ P 〈 0.05 ）. Correlation analysis showed that there was a positive correlation in mRNA （0. 918,P 〈 0.01 ） and protein expression （0. 856, P 〈 0. 01 ） between HIF-1α and VEGF, while there was a negative correlation in mRNA （ - 0. 709, P 〈 0. 05 ） and protein expression （ - 0. 667, P 〈 0. 05 ） between HIF-1α and E-cadherin. Conclusion The effects of CO2 pneumoperitoneum on HIF-1α, VEGF and E-cadherin expression of renal cell carcinoma cells might be mediated by hypoxia, and HIF-1α might be the initiation factor of regulatory network of RCC-949 tumorigenicity in artificial CO2 pneumoperitoneum. Key words: Renal cell carcinoma; Pneumoperitoneum ; Hypoxia inductive factor-1α; Vascular endothelial growth factor; E-cadherin