A precise, rapid and sensitive in vitro assay to measure the adhesion of ovarian tumour cells to peritoneal mesothelial cells.

Ovarian cancer is the second most common gynaecological cancer in the UK, causing 2000 deaths per year. It spreads by shedding cells which attach to the mesothelial lining of the peritoneal cavity. In order to quantitatively study this interaction, a model system was developed in which mesothelial cells were cultured as monolayers in multiwell plates, and ovarian tumour cells were added that had been pre-labelled with a fluorescent dye (calcein). Synchronous interaction between the two populations was achieved by brief centrifugation at low g and the degree of attachment was measured on an automated fluorimeter after washing away the unbound cells. Using this procedure it was possible to measure tumour cell adhesion in 96 wells in 3-4 h. The reproducibility of the method was high even after short incubation times and the background absorbance was so low that the adhesion of less than a 1000 cells could be easily detected. The method works equally well for all ovarian tumour cell lines so far studied, and in preliminary experiments, it was shown that it can be used to screen for the effects of various blocking agents.