Liver plasma membranes and proteoglycan prepared therefrom inhibit the growth of hepatoma cells in vitro.

1. Plasma membranes from rat liver or kidney inhibited the growth of hepatoma (AH-130) cells in vitro. AH-130 plasma membranes or erythrocyte ghosts inhibited the growth of AH-130 cells less effectively. The inhibitory activity of liver plasma membranes was lost by heat treatment, or mild protease (papain or bromelin, but not trypsin or pronase) treatment, whereas it was retained after sialidase treatment of delipidation by ethanol/ether. 2. Proteoglycan (proteoheparan sulfate) prepared from liver plasma membranes inhibited the growth of AH-130 cells, but heparan sulfate was less active. The inhibitory activity of liver plasma membranes seemed, however, not to be ascribable solely to proteoheparan sulfate associated with plasma membranes. 3. Preliminary investigation suggested that the molecular weight 40 000 component may be a major inhibitory principle in liver plasma membranes.