A NOVEL POLYMERIC SPERMINE CONJUGATE INHIBITS POLYAMINE TRANSPORT IN PULMONARY-ARTERY SMOOTH-MUSCLE CELLS

The polyamines putrescine, spermidine and spermine (SPM) are low molec ular weight organic cations that play essential intracellular regulato ry roles in cell growth and differentiation. Whereas both de novo poly amine synthesis and transmembrane transport regulate cell polyamine co ntents, exploitation of pathways as pharmacologic targets has been lim ited by the lack of agents which specifically block polyamine transpor t. We now report the synthesis acid biologic activity of novel polymer ic glutaraldehyde conjugates of putrescine, spermidine and SPM which a ct at the cell membrane to inhibit polyamine uptake in cultured bovine pulmonary artery smooth muscle cells. Each conjugate caused dose-rela ted inhibition of [C-14]polyamine transport in pulmonary artery smooth muscle cells with the polymeric SPM conjugate being most effective in inhibiting the uptake of all three polyamines. Polymeric SPM failed t o impair uptake of neutral or charged amino acids or to associate with pulmonary artery smooth muscle cells in a temperature-dependent manne r. The polymeric SPM conjugate caused substantial decreases in cell po lyamine contents which were associated with concentration-dependent cy totoxicity. Spectroscopic analyses of the polymeric SPM conjugate indi cated that its molecular weight was 25 +/- 0.5 kDa, which is equivalen t to approximately 90 monomeric -HN(CH2)(3)NH(CH2)(4)NH(CH2)(3)NH(CH2) (5)- units. These findings indicate that reduced polymeric glutaraldeh yde conjugates of the polyamines may function as specific inhibitors o f polyamine transport and thus provide a basis for examination of poly amine transport as a pharmacologic target in disorders characterized b y dysregulated cell growth and differentiation.