Tumor Infiltrating Neutrophils Play A Critical Role In Non-small Cell Lung Cancer Metastasis

Background:Metastasis is the main cause of cancer mortality and a new insight that different, faster mechanism drove cancer cells dissemination in the early stage of tumor progression was uncovered. Cancer-related inflammation, especially tumor infiltrating neutrophils, lymphocytes and macrophages, are related to tumor progression. The main aim of this study was to characterize inflammatory cells in primary and metastases tumors of non-small-cell lung cancer (NSCLC) and explore which kind of inflammatory cells play a critical role in metastases. Additionally, the corresponding peripheral blood inflammatory cells were explored.Methods:A total of 82 NSCLC patients were studied in the retrospective study, including 41 patients with metastasis and 41 paired patients without metastasis.123 NSCLC specimens were obtained from 41 patients with metastasis (both primary tumors and metastases) and 41 patients without metastasis (only primary tumors). Immunohistochemistry was applied to detect the infiltration of CD66b+neutrophils, CD8+ T lymphocytes, CD 163+ macrophages and the expression of E-cadherin and CXCL5 in the 123 specimens. Pearson chi-square test or Fisher exact test was used to detect the relationship between the tumor-infiltrating neutrophils or peripheral neutrophils and clinicopathological features. Wilcoxon signed rank test was used for the comparison of the infiltration of inflammatory cells between the primary tumors and metastases of patients with metastasis, also for the comparison between the primary tumors of patients with metastasis and the primary tumors of patients without metastasis. Spearman rank test was applied for the study of correlation. p<0.05 was considered statistically significant.Results:The infiltration of CD66b+neutrophils in primary tumors of patients with metastasis was higher than corresponding metastases (p<0.001) and primary tumors of patients without metastasis (p<0.001). However, no significant difference was shown for CD8+ T lymphocytes (p=0.288,p=0.325) and CD 163+ macrophages (p=0.726, p=0.975). We also found that CD66b+ neutrophils infiltration was positively correlated with CXCL5 expression (Spearman’s correlation coefficient =0.505, p<.001) and negatively related to E-cadherin expression (Spearman’s correlation coefficient=-0.479, p<0.001). In addition, TIN was positively correlated with circulating neutrophils counts (Spearman’s correlation coefficient =0.493, p<0.001). Further studies showed that both TIN (Spearman’s correlation coefficient =0.415, p<0.001) and circulating neutrophils counts (Spearman’s correlation coefficient=0.334,p=0.002) were correlated with the number of positively-metastasis lymph nodes.Conclusions:Our study demonstrated that CD66b+ neutrophil, as a particular subset of inflammatory cells, mainly accumulated in primary tumors, while other subsets of immune cells including lymphocytes and macrophages were equally represented in primary tumors and metastases tumors. Neutrophils play a critical role in NSCLC metastases, partly via the ability to induce epithelial-mesenchymal transition. Furthermore, circulating neutrophils which were related to TIN could be a simple and easy monitoring indicator for metastasis of NSCLC.