cgp-48664 and pimagedine

We investigated whether in vitro L1210 growth inhibition by alpha-difluoromethylornithine (DFMO; 740 microM) and 4-amidinoindan-1-one 2'-amidinohydrazone (CGP 48664A; 1.7 microM) is reversible with N1-acetylspermine (N1-acSp). Influences of N1-acSp dose (1-100 microM), time (0-12 h at 100 microM), aminoguanidine (AG, 1 mM) and cell numbers (at 1 microM N1-acSp) on percentage S-phase, polyamine contents and viability were determined. DFMO/CGP 48664A decreased percentage S-phase from 58 to 26%, decreased spermidine (Sd) and spermine (Sp) contents 3-fold, but did not affect viability. With increasing N1-acSp dose, S-phase percentage and Sd contents increased concomitantly, reaching plateau values that were comparable with those of untreated controls. S-phase and Sd content increased from 4-6 h after N1-acSp administration, reaching plateau values from 11 and 6 h, respectively. N1-acSp content was dose dependent and increased linearly to reach plateau values from 8 h. AG did not affect any of these parameters. Addition of 1 microM N1-acSp to decreasing numbers of DFMO/CGP 48664A-treated cells caused increasing S-phase percentage, Sd and N1-acSp contents. We conclude that cell cycle kinetics of cultured L1210 cells can be manipulated by the induction of growth inhibition with DFMO/CGP 48664A and its subsequent abolishment with N1-acSp. N1-acSp accumulation rate and its subsequent conversion to Sd is relatively slow compared with intracellular Sd needs. The data support the notion that Sd is the most important polyamine for growth.

Topics: Amidines; Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Count; Cell Cycle; DNA; Dose-Response Relationship, Drug; Eflornithine; Guanidines; Indans; Leukemia L1210; Mice; Spermine; Tumor Cells, Cultured