Radiation sensitivity of human ovarian carcinoma cell lines in vitro: effects of growth factors and hormones, basement membrane, and intercellular contact.

The radiation sensitivity of six established human ovarian carcinoma cell lines was determined in vitro under five different experimental conditions. Cells from exponentially growing monolayer cultures were assayed under three different post-irradiation culture conditions, i.e., conventional conditions on a plastic surface, in the presence of growth factors and hormones, and on a basement membrane. Multicellular aggregates were dissociated either immediately before or immediately after irradiation and assayed under conventional conditions. The radiation sensitivity differed considerably among the cell lines; the initial slope alpha ranged from 0.05 +/- 0.03 Gy-1 to 0.36 +/- 0.07 Gy-1 and the surviving fraction at 2.0 Gy from 0.32 +/- 0.06 to 0.78 +/- 0.06 under conventional conditions. There was no significant effect of the growth factors and hormones and of the basement membrane on the survival curves for any of the cell lines. Only one of the lines showed a significant intercellular contact effect. The presence of this effect required that the cells were grown as aggregates, but was independent of whether the irradiation was performed on dissociated or intact aggregates. The present work with established cell lines indicates that the outcome of an in vitro predictive assay for clinical radioresponsiveness of ovarian carcinomas would probably not vary significantly among the five experimental conditions studied here. However, further studies using cells isolated directly from human ovarian carcinoma surgical specimens are warranted.