CELL-CYCLE ARREST AND APOPTOSIS OF LEUKEMIA-CELLS INDUCED BY L-ASPARAGINASE

Apoptotic cell death of murine leukemia cells induced by E. coli L-asp araginase was studied. Deprivation of L-asparagine from the culture of L5178Y cells by L-asparaginase caused the fragmentation of chromosoma l DNA of the leukemia cells within 24 h. Prior to the degradation of D NA, cell cycles of L5178Y cells were found to be arrested in G1 phase, and evidence of the DNA strand breaks was initially observed in G1 ph ase cells as early as 8 h after the asparaginase treatment. Therefore, apoptosis of leukemia cells induced by L-asparaginase is an event tha t is associated with the cell cycle arrest in G1 phase.