The Serum Assay of Soluble CD44 Standard, CD44 Variant 5, and CD44 Variant 6 in Patients with Gastric Cancer

Alternative splicing of CD44 and aberrant levels of soluble CD44 (sCD44) protein in the serum of cancer patients has been correlated to tumor progression and metastasis. The purpose of this study was to evaluate the concentrations, and the prognostic potential of sCD44s, sCD44v5 and sCD44v6, in patients with gastric cancer.The serum levels of sCD44s, sCD44v5 and sCD44v6 were determined quantitatively using an enzyme-linked immunosorbent assay. Serum samples were obtained from 116 patients with gastric cancer, both before and after surgery, and from 30 healthy controls.The serum sCD44v6 levels were significantly higher in patients with gastric cancer than in the healthy controls, whereas those of sCD44s and sCD44v5 were no different. The surgical resection of the tumor resulted in a significant reduction in all the sCD44 proteins, whereas if a surgical resection was not performed the concentrations of the sCD44v5 and sCD44v6 were not reduced prior to surgery. The serum sCD44v6 levels correlated with the venous or lymphatic invasion of the tumor and lymph node metastasis. In addition, a high preoperative serum sCD44v6 level was significantly associated with poor prognosis in patients with gastric cancer.The preoperative serum level of sCD44v6 in patients with gastric cancer was significantly higher than that in the healthy controls, and correlated with the venous or lymphatic invasion of the tumor and lymph node metastasis. In addition, a high preoperative serum sCD44v6 level was significantly associated with poor prognosis in patients with gastric cancer. These results suggest that an elevation of the serum sCD44v6 level might be used as a new predictor of tumor invasiveness, and poor prognosis, in patients with gastric cancer.