Relationship between Osteopontin mRNA Expression and the Clinicopathological Staging of Gastric Cancer

Background: Osteopontin is a secreted phosphorylated glycoprotein that contains an integrin-binding motif GRGDS, which is involved in the cell signal transduction and may promote cell adhesion and migration. Recent studies have shown that overexpression of osteopontin is associated with infiltration and metastasis of many malignant tumors in human being. Aims: To explore the osteopontin mRNA expression in gastric cancerous tissues, and to analyze its relationship to the clinicopathological staging of gastric cancer. Methods: The specimens of cancerous tissues and the corresponding non-cancerous mucosa were obtained from 24 gastric cancer patients; Six gastric mucosal samples taken from healthy volunteers were served as controls. The osteopontin mRNA expression was detected with semi-quantitive reverse transcriptase polymerase chain reaction (RT-PCR). Results: The osteopontin mRNA expression in 6 controls was very low. Among the 13 stage Ⅰand Ⅱ gastric cancer patients, the osteopontin mRNA expression in cancerous tissues of 6 patients (46.2%) was higher than that in the corresponding non-cancerous mucosa, and in all 11 patients with stage Ⅲ and Ⅳ, the osteopontin mRNA in cancerous tissues was overexpressed (100%). With the advancement of clinicopathological staging of gastric cancer, both the osteopontin mRNA expression in cancerous tissues and its ratio to that in the non-cancerous mucosa were markedly increased. There were significant correlations between the relative expression amount of osteopontin mRNA in cancerous tissues and the degree of infiltration, vascular invasion, adjacent lymph node metastasis and distant metastasis of gastric cancer (P0.05), but not the differentiation of cancer cells. Conclusions: The osteopontin mRNA overexpression in cancerous tissues is closely related to the degree of infiltration, metastasis and clinicopathological staging of gastric cancer. Osteopontin can be used as an important marker in estimating the malignant degree and metastasis of gastric cancer.