Intercellular contact-dependent survival of human A549, NCI-H596 and NCI-H520 non-small cell lung carcinoma cell lines

In the present study, we examined the relationship between cell phenotype a nd cell survival of three human non-small cell lung carcinoma cell lines (A 549, NCI-H596 and NCI-H520). Cells in exponential growth at various densiti es were incubated for 24 h at 37 degreesC in a 5% CO2 humidified atmosphere and then exposed to UV radiation for I min (256 nm, 40 W, source-to-target distance 100 cm). After two days the surviving cells were quantified by su lforhodamine beta staining and DNA fragmentation assay. The differences in UV sensitivity at 60 x 10(3) cells/cm(2) among the cell lines were not rela ted to the proliferative state of the cells but to the extent of intercellu lar contact. In contrast to A549 and NCI-H596, irradiated NCI-H520 cells pr esented lower DNA fragmentation and an aggregated cell culture phenotype ev en prior to confluence. suggesting that a contact-effect mechanism provides further protection against UV radiation.