Association of progression and reduced expression of VLA-2 in gastric cancer

We investigated the expression of VLA-2 in gastric cancers by immunohistochemistry using anti-integrin alpha 2 and beta 1 antibodies and the data were compared with the pathological findings of each gastric cancer. The specimens were stained with an immunohistological technique for integrin alpha 2 and beta 1 subunits. Tumors, simultaneously expressing both integrin alpha 2 and beta 1 subunits were defined as positive for VLA-2. Tumors expressing either subunits of integrin alpha 2 or beta 1 or those showing reduced expression of both subunits were defined as VLA-2 negative tumors. In the 77 primary tumors, 55 (71%) were VLA-2 positive. 38 (90%) of 42 tumors showing differentiated type including tubular adenocarcinoma and papillary adenocarcinoma expressed VLA-2, whereas 19 (55%) out of 35 undifferentiated type of cancers including poorly differentiated adenocarcinoma, mucinous carcinoma and signet ring cell carcinoma stained for VLA-2. In the undifferentiated type of cancers, VLA-2 negative tumors had a significantly higher incidence of vessel invasion than VLA-2 positive ones (p<0.05). VLA-2 negative tumors showed a tendency to peritoneal dissemination, lymph node metastases, lymphatic invasion or invasion beyond the subserosal layer. In the specimens of peritoneal dissemination, VLA-2 expression rate was found in 56% (9/16), with a higher expression rate than that of primary lesions. These data indicate that reduced expression of VLA-2 may strongly associate with vessel invasion especially in the undifferentiated type of adenocarcinoma of the stomach.