Interactions of lung cancer cells with the human mesothelial cell monolayer: an in vitro model for cancer invasion.

An in vitro monolayer model for cancer invasion was developed, comprising cultured layers of human pleura-derived mesothelial cells (PM cells). The cells were isolated from normal human pleura at autopsy and cultured in RPMI-1640 supplemented with 10% fetal calf serum; they were polygonal in shape, forming a pavement-like structure, and preserved the morphologic characteristics of mesothelial cells. When small cell lung cancer cells (OC-10 cells) were seeded on to the monolayer of PM cells, they attached themselves to the monolayer, invaded it and formed flattened cancer cell nests beneath it. By counting the number of cancer cells penetrated, the in vitro invasiveness (invasive capacity) of the cancer cells was assayed. The invasive capacity of poorly invasive cells (10N), which were cloned from OC-10 cells, was five times less than that of the parental OC-10 cells. These results indicate our system to provide a useful model for studying human cancer cell invasion.