Background: The growth rate of a tumor is dependent on both cell proliferation and cell loss. We have established subpopulations of human colon cancer cells with different in vivo growth rates by selecting the cells according to their adhesiveness to laminin-1 in vitro.

Materials and methods: Laminin-1-adhesion selected colon cancer cells were injected into the cecal wall of nude mice. The tumors were examined 30 days later. Cell proliferation was assessed by proliferating cell nuclear antigen (PCNA) index and apoptotic cells were labeled by digoxigenin-11-dUTP using terminal deoxynucleotidyl transferase.

Results: The laminin-1-adherent cells, which formed larger tumors in vivo, showed increased proliferative activity and reduced apoptosis in comparison with the laminin-1-nonadherent cells.

Conclusion: Laminin-1 may enhance the malignant behavior of colon cancer cells by accelerating proliferation as well as by decreasing cell loss.