Stage-dependent angiopoietin-Tie2 and nitric oxide signaling of erythrocytes in response to surgical trauma in head and neck cancer

Background: Angiopoietin-Tie2 and nitric oxide pathway is crucial in tumor angiogenesis and closely correlates with tumor development, growth, and metastasis. This study aimed to investigate the angiopoietin-Tie2 and nitric oxide signaling of the erythrocyte membrane in response to surgical trauma in head and neck cancer. Methods: We prospectively enrolled the patients with histology-proven head and neck squamous cell carcinoma undergoing surgical resection of primary tumors at the medical center between August and November 2019. We measured the preoperative and postoperative levels of angiopoietin-1, angiopoietin-2 in plasma using enzyme-linked immunosorbent assays, nitric oxide in plasma using nitrate/nitrite colorimetric assays, and Tie2 phosphorylation in erythrocyte membrane using Western blotting. Results: The plasma angiopoietin-1 was downregulated from the median 971.3 pg/mL (interquartile range [IQR] 532.1-1569.3) to 417.9 (IQR 270.5-597.3) after tumor resection (p = 0.0020). Conversely, the plasma angiopoietin-2 was enhanced from 1173.6 pg/mL (IQR 977.7-1450.2) to 2353.7 (IQR 1352.4-2954.3) after surgery (p = 0.0021), with a concomitant increase in plasma nitric oxide level from 7.73 μM (IQR 5.39-10.06) to 10.50 (IQR 7.65-14.18) after surgical resection (p = 0.0093). Subgroup analyses further showed the angiopoietin-Tie2 and nitric oxide signaling was significant only in stage III and IV cancer. Conclusions: The dynamic change of angiopoietin-Tie2 signaling in the erythrocyte membrane along with the enhanced nitric oxide in plasma after tumor resection suggests erythrocytes play a significant role in modulating surgery-induced angiogenesis, which may provide a novel marker for cancer surveillance and control.