IN-VITRO MANIPULATION OF L1210 CELL-CYCLE KINETICS WITH 4-AMIDINOINDAN-1-ONE 2'-AMIDINOHYDRAZONE, ALPHA-DIFLUOROMETHYLORNITHINE AND N-1-ACETYLSPERMINE

We investigated whether in vitro L1210 growth inhibition by alpha-difl uoromethylomithine (DFMO; 740 mu M) and 4-amidinoindan-l-one 2'-amidin ohydrazone (CGP 48664A; 1.7 mu M) ii reversible with N-1-acetylspermin e (N-1-acSp). Influences of N-1-acSp dose (1-100 mu M), time (0-12 h a t 100 mu M), aminoguanidine (AG, 1 mM) and cell numbers (at 1 mu M N-1 -acSp) on percentage S-phase, polyamine contents and viability were de termined. DFMO/CGP 48664A decreased percentage S-phase from 58 to 26%, decreased spermidine (Sd) and sl,ermine (Sp) contents 3-fold, but did not affect viability. With increasing N-1-acSp dose, S-phase percenta ge and Sd contents increased concomitantly, reaching plateau values th at were comparable with those of untreated controls. S-phase and Sd co ntent increased from 4-6 h after N-1-acSp administration, reaching pla teau values from 11 and 6 h, respectively. N-1-acSp content was dose d ependent and increased linearly to reach plateau values from 8 h. AG d id not affect any of these parameters. Addition of 1 mu M N-1-acSp to decreasing numbers of DFMO/CGP 48664A-treated cells caused increasing S-phase percentage, Sd and N-1-acSp contents. We conclude that cell cy cle kinetics of cultured L1210 cells can be manipulated by the inducti on of growth inhibition with DFMO/CGP 48664A and its subsequent abolis hment with N-1-acSp. N-1-acSp accumulation rate and its subsequent con version to Sd is relatively slow compared with intracellular Sd needs. The data support the notion that Sd is the most important polyamine f or growth. (C) 1998 Elsevier Science B.V. All rights reserved.