Increased expression of α2β1-integrin in the peritoneal dissemination of human gastric carcinoma

The prognosis of advanced gastric cancer remains poor, given the frequent incidence of peritoneal metastasis. beta 1-integrin is known to be associated with metastasis, though few reports have addressed the expression of beta 1-integrin subunits in gastric cancer at primary and peritoneal lesions from the perspective of individual cases. We studied specimens from primary tumors from 50 patients and from metastatic peritoneal lesions from 27 patients with gastric carcinoma, including specimens from 22 metastatic lesions taken from the same patients whose primary tumors were sampled. Expression of beta 1-integrin subunits, alpha 2-alpha 6 beta 1 integrins, was studied using an immunohistochemical method. alpha 2 beta 1-integrin was significantly expressed on a larger proportion of tumor cells in peritoneal metastasis (70.4%) than in primary tumors (48%) (p<0.05), though alpha 3 beta 1, alpha 4 beta 1, alpha 5 beta 1 and alpha 6 beta 1-integrins did not demonstrate significant discrepancy. The expression of alpha 2 beta 1-integrin in peritoneal lesions was significantly increased compared with its expression in the primary lesion in the same individual. In contrast, no relationship was found between the expression level of beta 1 integrins and clinicopathological parameters. Peritoneal implantation of gastric carcinoma might be closely associated with alpha 2 beta 1-integrin.