Suppression by interferon-gamma of tumor cell-induced increase in mesothelial permeability

The effect of interferon-gamma (IFN-gamma) on the interaction between tumor cells and mesothelial cell layers was studied from the aspect of changes in mesothelial permeability. Mesothelial permeability was assessed as the percentage diffusion of radiolabeled albumin across the mesothelial cell sheets on Matrigel-coated filter cup assemblies. When lined gastric carcinoma cells (KATO-III) were seeded on the confluent mesothelial cell layers, the fine cobblestone appearance of the cell sheet was disrupted and mesothelial permeability significantly increased. The increase in permeability was suppressed by the addition of as little as 1 U/ml of IFN-gamma. The effect of IFN-gamma was observed when either the conditioned medium of tumor cells alone or the IFN-gamma-resistant tumor cells, K-562, was placed onto the mesothelium. The cobblestone appearance of the cell sheet was relatively well preserved in the presence of IFN-gamma. In contrast, IFN-alpha did not suppress tumor-induced mesothelial permeability. These results suggest that IFN-gamma has the potential to protect the human mesothelial cell layers against tumor cells.