[Establishment of an experimental model for tumor cell invasion and potentiation and inhibition of the invasive capacity].

Seeding of rat ascites hepatoma cells (AH 130) on cultured mesothelial cell monolayers resulted in the penetration of single tumor cells and subsequent formation of tumor cell colonies underneath the monolayers. Determination of the number of colonies facilitated quantitative estimation of the in vitro invasive ability, which corresponded well with the in vivo invasive capability of the tumor cells. Preculture of AH 130 cells with macrophages greatly potentiated both the in vitro and in vivo invasive capacities of the tumor cells. This potentiation seems to be mediated by certain species of active oxygen radicals generated by macrophages. Acid/ethanol extract of normal rat liver inhibited both the in vitro and in vivo invasion by the tumor cells. The inhibiting entity in the extract was heat-stable and had a molecular weight in the range of 3.5-10 Kd. It did not suppress tumor cell attachment to mesothelial cell layers, or inhibit tumor cell growth, but selectively impaired the penetration step of the tumor cell invasion through its binding to the tumor cell surface.