INTERACTION OF A POLYAMINE ANALOG, 1,19-BIS-(ETHYLAMINO)-5,10,15-TRIAZANONADECANE (BE-4-4-4-4), WITH DNA AND EFFECT ON GROWTH, SURVIVAL, AND POLYAMINE LEVELS IN 7 HUMAN BRAIN-TUMOR CELL-LINES

Computer graphics modeling and physicochemical studies of spermine-DNA interactions, as well as experiments in cell culture, indicate that a polyamine analogue with strong affinity for nucleic acids but poor ab ility to condense and aggregate DNA in vitro should act as an antiprol iferative agent if it can enter cells. On the basis of our studies of polyamine-DNA interactions, we designed a pentamine, 1,19-bis(ethylami no)-5,10,15-triaz-anonadecane (BE-4-4-4-4), that had these characteris tics. Measurement of melting temperature and ultraviolet light scatter ing studies show that the affinity of this analogue for calf-thymus DN A is about 4 times higher than that of spermine, whereas its ability t o aggregate DNA is slightly poorer than that of spermine. Studies in U -87 MG, U-251 MG, SF-126, SF-188, SF-763, SF-767, and DAOY human brain tumor cells in tissue culture showed that treatment for more than 96 h with concentrations of 5 muM BE-4-4-4-4 or greater inhibited growth; decreased levels of putrescine, spermidine, and spermine; and decreas ed colony-forming ability in all cell lines. The cytotoxicity of the a nalogue varied among cell lines; DAOY and SF-767 were the most sensiti ve and the most resistant lines, respectively. In SF-763 cells, growth inhibition by BE-4-4-4-4 could be partially reversed by the addition of putrescine, spermidine, or spermine 1 day after BE-4-4-4-4 addition , but in U-251 MG cells, growth inhibition was reversed only by spermi ne and not by other polyamines. When any of the naturally occurring po lyamines was added simultaneously with BE-4-4-4-4, growth inhibition w as completely blocked. The data suggest that a threshold intracellular concentration of BE-4-4-4-4 is needed to manifest the growth-inhibito ry and cytotoxic effects. In most cell lines, once that threshold leve l is reached, the growth-inhibitory and cytotoxic properties of the an alogue are manifest irrespective of cellular polyamine levels. Further increases in the BE-4-4-4-4 concentration or incubation time reduce t he intracellular polyamine levels but do not significantly increase gr owth inhibition. In U-87 MG and DAOY cells, however, prolonged incubat ion with higher concentrations of BE-4-4-4-4 causes additional growth inhibition along with depletion of intracellular polyamines. Thus, it appears that polyamine analogues having higher affinity for DNA than n atural polyamines can inhibit cell growth even in the presence of natu ral polyamines, if they are taken up by cells to a sufficient degree t o compete with and displace natural polyamines from their binding site s on DNA.