Objective  To measure the expression of signal-induced proliferation-associated gene 1 (Sipa1) in gastric cancer and to determine its association with the clinicopathological characteristics and prognosis of patients with gastric carcinoma.

  Methods  The Sipa1 mRNA and Sipa1 protein expression levels in 43 fresh gastric carcinoma tissues and adjacent normal tissues were measured by real-time PCR and Western blot analysis. The Sipa1 protein expression levels in 122 paraffin blocks of gastric cancer and 64 normal gastric tissues were determined by substance P immunohistochemical technique.

  Results  The Sipa1 mRNA and Sipa1 protein levels in fresh gastric carcinoma tissues were significantly lower than those in adjacent normal tissues. Sipa1 protein was positive in 36.1% of the paraffin blocks of gastric cancer and in 73.4% of normal gastric tissues. The difference was statistically significant (P < 0.05). Sipa1 protein expression was significantly correlated with tumor differentiation, lymphatic metastasis, invasive depth, and clinical stage (P < 0.05) but not with age, gender, tumor size, and tumor areas (P>0.05). The five-year survival rates of Sipa1-negative patients were significantly lower than those of Sipa1-positive patients (P < 0.01).

  Conclusion  Sipa1 expression is highly correlated with the biological behavior of gastric carcinoma and thus facilitates the evaluation of gastric carcinoma prognosis.