Lethal Effect of Adriamycin on the Division Cycle of HeLa Cells1

Adriamycin, a new antitumor antibiotic in the anthracycline group, promptly inhibits DNA and RNA synthesis and arrests cell division. The cell viability (defined as the capacity of a single cell to grow out into a macroscopic clone) is reduced sharply following exposure to adriamycin, 0.1 fig/ml, for a fractional period of the generation time. With the use of a synchronous population of HeLa cells, it is shown that the maximum loss in cell viability takes place when exposure to adriamycin occurs during the DNA-synthetic phase (S). The relative dose-response curves of HeLa cells exposed to either adriamycin or daunomycin show that daunomycin is significantly more effective in reducing the cell viability than is adriamycin on a molar basis. elsewhere (3). Tests for contamination of the HeLa cultures with mycoplasma were negative. Synchronous cultures were obtained by selective collection and plating of mitotic cells (5). Labeling procedure, autoradiography, and determination of nucleic acids and protein have been described in detail elsewhere (6). Cell counts were performed with a Model B Coulter counter. Plating for colony counts was carried out with 60-mm plastic Petri dishes. Control and adriamycin-treated plates prepared from trypsinized single cell suspensions or harvested mitotic cells (500 cells/plate) were incubated for 12 days at 37°.Colonies were fixed with methanol, stained with crystal