Laminin deposition to type IV collagen enhances haptotaxis, chemokinesis, and adhesion of hepatoma cells through beta 1-integrins

Background/Aims: In hepatocellular carcinoma, laminin deposition to type IV collagen along the sinusoids is observed with the development of arterial network, coinciding with intrahepatic metastasis. We investigated the influ ence of laminin deposition to type IV collagen on hepatoma cell adhesion, m otility and secretion of matrix metalloproteinases (MMPs), which are indisp ensable behaviors for tumor metastasis. Methods: Hepatoma cell lines (KYN-1, -2 and -3) were used. The expression o f integrin subunit mRNAs in hepatoma cells was confirmed by RT-PCR. The inf luence of laminin addition to type TV collagen on the adhesion, chemokinesi s, and migration of KYN-1, -2 and -3 was evaluated by the haptotactic migra tion, phagokinetic track motility, and cell adhesion assays. The effects of integrin subunits on these activities were evaluated using the function-bl ocking antibodies for integrins. Phosphorylation of MEK1/2 and secretion of MMPs were investigated by Western blotting and gelatin zymography. Results: Integrin alpha1, alpha2, alpha3, alpha6 and beta1 subunit mRNAs we re detected. The combination of type IV collagen and laminin enhanced the m igration, chemokinesis, and adhesion of hepatoma cells compared to that of type IV collagen when used alone. The enhanced activity was significantly s uppressed by function-blocking antibodies for integrin al, alpha2, alpha3, alpha6 and beta1 subunits. Hepatoma cells cultured on the combination of ty pe IV collagen and laminin showed phosphorylation of MEK1/2 and increased s ecretion of MMPs. Conclusions: The addition of laminin to type IV collagen enhances hepatoma cell adhesion and motility through beta1-integrins. (C) 2001 European Assoc iation for the Study of the Liver. Published by Elsevier Science B.V. All r ights reserved.