[Clinical significance of S100A8 and S100A9 expression in gastric cancer].

Objective: To explore the expressions of S100A8 and S100A9 in gastric cancer.

Methods: A total of 176 patients with gastric cancer, including 124 males and 52 females, were recruit from 1998 to 2004, average age 57(26-80)years. The expressions of S100A8 (n = 125) , S100A9 (n = 176) and S100A8/A9 heterodimer (calprotectin) in gastric tissue samples were assessed by immunohistochemistry and immunofluorescence. The co-localization of S100A9 and its dimerization partner S100A8 and heterodimer S100A8/A9 were examined by laser confocal scanning.Receiver operator characteristic (ROC) curve was used in determining the cut-off value of S100A9 and S100A8-positive inflammatory cell counts in evaluating the pathological TNM stage. To obtain associations between S100A9 or S100A8 cell counts and clinicopathologic variables, the data were cross-tabulated and χ(2)-test was performed. Cumulative survival was estimated by the Kaplan-Meier method.

Results: ROC curves using the S100A9 and S100A8-positive inflammatory cell counts were 0.623 and 0.522 for pathological TNM stages respectively. The cutoff values were 200 and 65 per 200× magnification field with a sensitivity of 61.48% and 51.09% and a specificity of 64.29% and 51.52% respectively. Patients with S100A9 positive expression (n = 77) had better overall survival than negative expression(n = 99) ((35.1 ± 10.8) vs (20.3 ± 3.0) months, P = 0.021). There was no statistical significance between S100A8 positive expression(n = 62) and negative expression(n = 63) ((26.4 ± 2.8) vs (29.5 ± 2.9) months, P = 0.145).In gastric cancer tissues, both S100A9 and S100A8 proteins were detected in tumor-infiltrating inflammatory cells while no case of S100A8/A9 heterodimer was found. In addition, S100A9 and S100A8 proteins were detected in inflammatory cells in chronic gastritis. Distribution of these two proteins also partly overlapped.

Conclusions: S100A9 positive expression in gastric cancer tissues is associated with an excellent prognosis. But S100A8 positive expression has no prognostic association. Calprotectin expression differs between gastric cancer and gastritis.Further explorations are warranted.