Drug-induced death of leukaemic cells after G2/M arrest: higher order DNA fragmentation as an indicator of mechanism

• Published in: British journal of cancer 1998-01, Vol.77 (1), p.40-50
• Main Authors: Sleiman, RJ, Catchpoole, DR, Stewart, BW
• Format: Article
• Language: English
• Subjects: Antineoplastic agents; Antineoplastic Agents, Phytogenic - pharmacology; Apoptosis - drug effects; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Cancer Research; Cell Division - drug effects; Cell Size - drug effects; Chemotherapy; Coloring Agents; DNA Fragmentation; DNA, Neoplasm; Drug Resistance; Electrophoresis, Gel, Pulsed-Field; Epidemiology; Etoposide - pharmacology; experimental-oncology; G2 Phase - drug effects; Gene Expression - drug effects; Humans; Leukemia - genetics; Leukemia - pathology; Medical sciences; Mitosis - drug effects; Molecular Medicine; Oncology; Pharmacology. Drug treatments; Polymerase Chain Reaction; Trypan Blue; Tumor Cells, Cultured - drug effects
• ISSN: 0007-0920; 1532-1827
• DOI: 10.1038/bjc.1998.7

Many reports have documented apoptotic death in different cell types within hours of exposure to cytotoxic drugs; lower drug concentrations may cause cell cycle arrest at G2/M and subsequent death, which has been distinguished from 'classic' apoptosis. We have analysed etoposide-induced cell death in two lymphoblastoid T-cell lines, CCRF-CEM and MOLT-4, specifically in relation to DNA cleavage as indicated by pulse-field gel and conventional electrophoresis. High (5 microM) concentration etoposide causes 50-kb cleavage of DNA that occurs at the same time as apoptotic morphology and internucleosomal cleavage. At lower concentrations (0.5-0.05 microM), sequential change may be discerned with altered gene expression being similar to that at high dose, but preceding cell cycle arrest and 50-kb cleavage. These last changes, in turn, clearly precede internucleosomal fragmentation of DNA, vital dye staining and morphological evidence cell death. The pattern of higher order fragmentation constitutes a sensitive indicator of commitment to cell death in these cells. Morphological evidence of cell death is associated with internucleosomal fragmentation in one of the lines, but the pattern of 50-kb DNA cleavage provides the clearest evidence of commonality in death processes occurring at low and high drug concentration.