CELL-DEATH BY APOPTOSIS FOLLOWING ANTICANCER DRUG-TREATMENT IN-VITRO

The mechanism of cell death, apoptosis or necrosis, was determined mor phologically and by DNA gel electrophoresis in 3 human leukaemic T-cel l lines (CCRF-CEM.f2, CCRF-HSB and MOLT.4) after treatment with cytoto xic drugs. These include one hormone, dexamethasone (DXM); the DNA dam aging agents, melphalan, cisplatin, bleomycin, mitomycin C and mithram ycin; inhibitors of DNA synthesis, aphidicolin, cytosine arabinoside ( Ara-C), methotrexate (MTX), 5-fluoro-2'-deoxyuridine (FUdR) and 5-fluo rouracil (5-FU); and other metabolic inhibitors, bromo-2'-deoxy-2'-uri dine (BUdR), actinomycin D, 5-azacytidine (5-AC), cycloheximide, vincr istine, etoposide and adriamycin. When cell death was assessed morphol ogically apoptotic cell death was apparent in the three cell lines 48 hours after all drug treatments. However, a distinct pattern of DNA br eakdown was observed for each cell line. A smear of DNA on agarose gel s was seen for CCRF-CEM.f2 with 5-FU and mithramycin treatments whilst CCRF-HSB cells showed a similar DNA profile after 5-FU and MTX treatm ents. All drug treatments of MOLT.4 cells produced a necrotic pattern of DNA degradation. Cycloheximide, an inhibitor of protein synthesis r educed DNA fragmentation of CCRF-CEM.f2 cells treated with DXM, MTX an d FUdR indicating that protein synthesis is required for cytotoxicity by apoptosis. However, the extent of DNA fragmentation caused by 5-FU was not significantly affected by cycloheximide. These results indicat e that at least morphological and electrophoretic criteria should be u sed to avoid differing conclusions about modes of cell death.