CD177⁺ neutrophils suppress epithelial cell tumourigenesis in colitis-associated cancer and predict good prognosis in colorectal cancer

Neutrophils are found to be infiltrated in tumour tissues of patients with colitis-associated cancer (CAC) and colorectal cancer (CRC), and CD177 is mainly expressed in neutrophils. In our study, expression of CD177 in tumour tissues from patients with CAC or CRC was analysed byquantitative real-time polymerase chain reaction, flow cytometry and immunohistochemistry. We recruited 378 patients with CRC, determined CD177 expression in tumours and examined its correlation with clinicopathological features. Moreover, CAC model was induced in wild-type and CD177^-/- mice by azoxymethane/dextran sodium sulphate. CD177⁺ neutrophils were significantly increased in colon tumour tissues from patients with CRC or CAC compared with controls. Expression of CD177 mRNA and percentages of CD177⁺ neutrophils were also markedly increased in tumour tissues from CRC patients compared with controls. Patients with high density of CD177⁺ neutrophils had better overall survival and disease-free survival compared with controls. Multivariate analyses revealed that the density of CD177⁺ neutrophils was an independent factor in predicting overall survival and disease-free survival. Consistently, CD177 depletion aggravated azoxymethane/dextran sodium sulphate-induced CAC in mice. Expression of Ki67 and proliferating cell nuclear antigen was increased in tumour tissues from CD177^-/- mice compared with wild-type counterparts. Moreover, CD177^-/- neutrophils failed to migrate in response to fMLP[AU: Please expand fMLP, DN, TNM and HIF-1a.] stimulation compared with wild-type controls. Our data indicate that CD177⁺ neutrophils suppress epithelial cell tumourigenesis and act as an independent factor in predicting the prognosis in patients with CRC. CD177⁺ neutrophils may serve as a novel therapeutic target in the treatment and predict the prognosis of CAC and CRC.