Effects of integrins on laminin chemotaxis by hepatocellular carcinoma cells.

To quantitatively evaluate the effects of integrins alpha1beta1, alpha2beta1, alpha3beta1, alpha4beta1, alpha5beta1, and alpha6beta1 on the chemotaxis of hepatocelluar carcinoma (HCC) cell line SMMC-7721 to laminin (LN). A modified dual-micropipette system was used to dynamically and quantitatively monitor the formation of pseudopod protrusion of HCC cells toward LN in the presence or absence of specific antibodies against integrins alpha1, alpha2, alpha3, alpha4, alpha5, alpha6, and beta1. Additionally, the expression levels of different integrin subunits on the surface of the cells were determined via flow cytometry analysis. In response to equal concentrations of LN in both micropipettes, HCC cells form symmetrical pseudopod protrusions on both sides. Addition of antibodies against alpha3, alpha6, or beta1 into one micropipette leads to significant reduction of pseudopod formation on that side, while antibodies against alpha1, alpha2, alpha4, and alpha5 do not affect the symmetrical formation of pseudopods in either micropipette. The percentages of HCC cells positive for expression of integrins alpha1, alpha2, alpha3, alpha4, alpha5, alpha6, and beta1 were 95.07, 23.17, 95.55, 2.47, 34, 14.29, and 95.78%, respectively. Integrins alpha3beta1 and alpha6beta1 are important cell surface receptors that mediate the chemotaxis of HCC cells toward LN.