Coordinated expression of integrin alpha 6 beta 1 and laminin in hepatocellular carcinoma

The interaction between tumor cells and laminin mediated by laminin-binding integrins is critical for tumor invasion and metastasis. The aim of this study was to clarify the altered expression of laminin-binding integrins with the change of laminin deposition in hepatocellular carcinoma (HCC) in comparison with cirrhotic or normal liver by immunohistochemistry. In HCC, hepatoma cells and sinusoidal endothelial cells expressed integrins alpha 1 beta 1, alpha 2 beta 1, alpha 3 beta 1, and alpha 6 beta 1. Integrins alpha 1 beta 1 and alpha 6 beta 1 were detected in a continuous pattern along the sinusoids in accordance with laminin assembly. Integrins alpha 2 beta 1 and alpha 3 beta 1 were detected in a discontinuous pattern at these sites. Integrin alpha 6 beta 4 was not detected. In cirrhotic liver, although integrins alpha 1 beta 1 and alpha 6 beta 1 as well as laminin were detected in a continuous pattern along the sinusoids, integrins alpha 2 beta 1, alpha 3 beta 1, and alpha 6 beta 4 were not detected. In normal Liver, although integrin alpha 1 beta 1 was detected in a continuous pattern along the sinusoids, neither integrins alpha 2 beta 1, alpha 3 beta 1, alpha 6 beta 1, alpha 6 beta 4, nor laminin were detected. We have clarified that, of laminin-binding integrins, the localization of integrin alpha 6 beta 1 shows the best correspondence with the localization of laminin. These results suggest that of laminin-binding integrins, integrin alpha 6 beta 1 is very important for cell-laminin interactions in HCC. Copyright (C) 1997 by W.B. Saunders Company.