Application of a novel method of double APAAP staining with subsequent quantitative image analysis to the examination of integrin expression in undifferentiated-type gastric carcinomas.

In undifferentiated-type gastric carcinoma (UGC), recognition of cancer cells is not easy, which has hampered its precise phenotypic analysis. To examine alterations of the integrin phenotype during the progression of UGC, we used double alkaline phosphatase anti-alkaline phosphatase staining and computer-aided image analyses for the expression of alpha1, alpha2, alpha3, alpha5, alpha6, alphaV, beta1, and beta4 integrin subunits and alphaVbeta3, alphaVbeta5, and alphaVbeta6 integrins in cytokeratin-positive cells in the mucosal, the submucosal, and the deeper parts of 10 early and 17 advanced UGCs, their non-neoplastic counterparts, and 9 lymph node (LN) metastases. We revealed declining expression of epithelial integrin subunits (alpha2, alpha3, alpha6, beta4) and increasing expression of mesenchymal integrin subunits (alpha1, alpha5) as the tumor invaded deeper, reflecting gradual epithelial-to-mesenchymal transition of the integrin phenotype during tumor invasion. Enhanced expression of the alphaV integrin subunit and alphaVbeta3 and alphaVbeta5 integrins correlated with tumor invasion, and that of alphaVbeta6 integrins with LN metastasis. Our results have demonstrated that the method we introduced is suitable for analysis of dynamic alterations of the integrin repertoire in UGC progression.