Down-regulated Expression of S100P in Gastric Cancer and Its Significance

Objective To investigate the expression of S100P on RNA and protein levels in relation to clinicopathological features with gastric cancer patients.Methods Expression of S100P in primary gastric cancer(n=93) was analyzed using immunohistochemistry.Then,immunoblotting and RT-PCR were conducted on part of immunohistochemical-positively stained gastric cancer tissues and matched gastric mucosas.Results The immunohistochemical staining for S100P was predominantly nuclear with some cytoplasmic staining in normal gastric mucosa.As a result,52.7%(49/93) of primary tumors and almost all the normal gastric mucosa were stained positively and S100P showed down-regulated expression in gastric cancer than in normal gastric mucosa.Further analysis with clinicopathologic data showed that the relative higher S100P expression strongly correlated with tumor infiltration depth(P=0.006) and tumor size(P=0.001).Meanwhile,the expression of S100P between RNA and protein level(results from immunohistochemistry) was closely correlated(P=0.024).But it can not be used as a dependent prognosis factor.Conclusion S100P was down-regulated in gastric cancer;S100P expression correlated with tumor infiltration depth and tumor size;Down-regulated expression of S100P can be used as a supporting marker for prognosis prediction.