20. S100A9-positive inflammatory cells in cancer tissues correlates with cancer stage and prognosis in patients with gastric cancer

Background: S100A9 was originally discovered expressed and released from inflammatory cells. Recently, it has been found to be associated with several human malignancies.
Materials and methods: In this study, S100A9, its dimerization partner S100A8, and S100A8/A9 heterodimer were assessed by immunohistochemistry in 176 gastric cancer patients.
Results: Results showed that S100A9 was specifically expressed by inflammatory cells infiltrating cancer and gastritis. Statistical analysis showed high S100A9 cell count (≥200) per 200× magnification field in cancer tissues was predictive of less advanced pathological stage. High S100A9 cell count was negatively correlated with lymph node metastasis (P=0.009) and tumor invasion (P=0.011). S100A9 was an independent prognostic predictor (P=0.04). Patients with high S100A9 cell count were with well prognosis (P=0.021). Furthermore, exogenous S100A9 protein exhibited inhibitory effects on migration and invasion of gastric cancer cells.
Conclusions: Our results suggested S100A9-positive inflammatory cells in cancer tissues are associated with gastric cancer stage and patient survival. Specific inflammatory cells within tumor microenvironment may affect biological behavior of adjacent cancer cells.