Invasive potentials of gastric carcinoma cell lines: Role of alpha(2) and alpha(6) integrins in invasion

The potentials of the two major histological types of gastric carcinoma to invade through extracellular matrices were studied with cell lines. We found that the invasive potential of intestinal-type carcinoma cells (MKN-28 and MKN-74) were higher than those of diffuse-type carcinoma cells (MKN-45 and KATO-III). To investigate whether the alpha(2) and alpha(6) integrin adhesion molecules are responsible for, or involved in carcinoma invasion, we further studied alpha(2) and alpha(6) expression patterns in these two types of cell line. Although fluorescence-activated cell sorting analysis revealed that all cells examined invariably expressed these integrin molecules, their expressional patterns were different among different cell lines. The intestinal-type carcinoma cells expressed integrins mainly along the cell-cell contact region, whereas the diffuse-type carcinoma cells showed a diffuse cytoplasmic pattern of integrin expression. Invasion by MKN-28, MKN-74 and MKN-45 cells through reconstituted basement membrane or type I collagen gel was significantly inhibited (P < 0.05) by 50 mu g/ml anti-(alpha(2) integrin) or anti-(alpha(6) integrin) monoclonal antibodies. Our results suggest that active invasiveness is stronger in the intestinal-type than in the diffuse-type carcinoma cells and that alpha(2) and alpha(6) integrins play important roles in invasion of both types of gastric carcinoma cell lines.