Introduction: This study aimed to explore the effect of carbon dioxide (CO₂) pneumoperitoneum on tumor proliferation and metastasis in an orthotropic xenograft nude mice model of human renal cell carcinoma (RCC) and evaluate the safety of CO₂ pneumoperitoneum laparoscopy for treating RCC.
Material and methods: RCC 786-0 cells were injected to establish an orthotropic xenograft model. Fifty nude mice were given orthotropic inoculations and randomized to five groups: group A (control); group B (CO₂ pneumoperitoneum for 2 h); group C (CO₂ pneumoperitoneum for 4 h); group D (CO₂ pneumoperitoneum for 4 h and 24 h after waking); group E (CO₂ pneumoperitoneum for 4 h and 48 h after waking). The proliferation status was observed in RCC specimens by immunohistochemical staining for Ki67. The protein levels of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were examined by western blotting.
Results: All groups showed similar Ki67-positive staining in RCC samples (p > 0.05). The relative expression of HIF-1α and VEGF gradually increased in both group B and group C, as compared with group A, but only the difference between group C and group A reached statistical significance (p < 0.05). The protein levels of HIF-1α and VEGF decreased in both group D and group E, as compared with group B and group C; however, the differences between group D, group E, and group A did not reach statistical significance (p > 0.05).
Conclusions: In an orthotropic xenograft nude mice model of RCC, CO₂ pneumoperitoneum has no effect on expression of the cellular proliferation marker Ki67. However, CO₂ pneumoperitoneum rapidly induces transient expression of HIF-1α and VEGF. Thus, CO₂ pneumoperitoneum laparoscopy may be a safe method for treating RCC.