Comparison of apoptotic, necrotic and clonogenic cell death and inhibition of cell growth following camptothecin and X-radiation treatment in a human melanoma and a human fibroblast cell line.

Abstract

We evaluated apoptotic, necrotic and clonogenic cell death and inhibition of cell growth in a human melanoma cell line (Sk-Mel-3) and a normal human fibroblast cell line (AG1522) following treatment with camptothecin (CPT) or with concurrent CPT and X-radiation. Apoptotic and necrotic cell death was determined morphologically by dual-staining (propidium iodide, acridine orange). Inhibition of cell growth was determined from the number of cells remaining in the culture dish following treatment. In Sk-Mel-3 cells: (a) after treatment with CPT alone, both apoptotic and necrotic cell death increased significantly ( P<0.05) relative to untreated controls; (b) after concurrent CPT and radiation treatment, however, only the increase in necrotic cell death was significant ( P<0.05) relative to cells receiving radiation alone; and (c) all assays of cellular effects/cytotoxicities were consistent in showing that CPT, given alone or with radiation, led to a substantial increase in cell kill. In contrast, in AG1522 cells: (a) there were no significant increases in apoptotic or necrotic cell death following either CPT alone or concurrent CPT and radiation; and (b) the clonogenic assay measured substantially higher cytotoxicities than the other assays. Necrotic cell death was more important than apoptotic cell death during concurrent CPT and radiation treatment in Sk-Mel-3 cells, but not in AG1522 cells.