Effect of propofol on lung metastasis of circulating tumor cells after colorectal cancer surgery

Abstract

Purpose: To investigate the effect of propofol on lung metastasis of circulating tumor cells (CTCs) after colorectal cancer (CRC) surgery, and the mechanism involved. Methods: Specific-pathogen-free (SPF) male BALB/c mice (n = 30; mean age = 7 ± 1 weeks; mean weight = 19 ± 3 g) were used for this study. To establish mouse model of CRC, 100 μL of CRC (CT26) cells was injected into the caudal vein of each mouse. Three groups of 10 mice were used: control, 5 μL/mL propofol, and 10 μL/mL propofol groups. Changes in pulmonary superficial nodules of mice lungs were determined. Colorectal cancer cell (CT26) proliferation and apoptosis were measured using Ki-67 immunohistochemical staining and in situ terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) assays, respectively. Results: The number of pulmonary nodules and proportion of proliferating cells (Ki-67 expression level) were significantly higher in 5 μL/mL propofol-treated mice, relative to control, but markedly lower in 10 μL/mL propofol group than in 5 μL/mL propofol group (p < 0.05). Although apoptotic index increased in 5 μL/mL propofol group, cell apoptosis was comparable among the groups (p > 0.05). Conclusion: These results suggest that propofol promotes pulmonary metastasis of CTCs after CRC surgery via stimulation of CTC proliferation in the lungs. Therefore, caution should be exercised in the use of propofol in colorectal cancer surgery.