Defining the Molecular Requirements for the Selective Delivery of Polyamine Conjugates into Cells Containing Active Polyamine Transporters

Abstract

Several N(1)-substituted polyamines containing various spacer units between nitrogen centers were synthesized as their respective HCl salts. The N(1)-substituents included benzyl, naphthalen-1-ylmethyl, anthracen-9-ylmethyl, and pyren-1-ylmethyl. The polyamine spacer units ranged from generic (4,4-triamine, 4,3-triamine, and diaminooctane) spacers to more exotic [2-(ethoxy)ethanoxy-containing diamine, hydroxylated 4,3-triamine, and cyclohexylene-containing triamine] spacers. Two control compounds were also evaluated: N-(anthracen-9-ylmethyl)-butylamine and N-(anthracen-9-ylmethyl)-butanediamine. Biological activities in L1210 (murine leukemia), alpha-difluoromethylornithine (DFMO)-treated L1210, and Chinese hamster ovary (CHO) and its polyamine transport-deficient mutant (CHO-MG) cell lines were investigated via IC(50) cytotoxicity determinations. K(i) values for spermidine uptake were also determined in L1210 cells. Of the series studied, the N(1)-benzyl-4,4-triamine system 6 had significantly higher IC(50) values (lower cytotoxicity) in the L1210, CHO, and CHO-MG cell lines. A cellular debenzylation process was observed in L1210 cells with 6 and generated "free" homospermidine. The size of the N(1)-arylmethyl substituent had direct bearing on the observed cytotoxicity in CHO-MG cells. The N(1)-naphthalenylmethyl, N(1)-anthracenylmethyl, and N(1)-pyrenylmethyl 4,4-triamines had similar toxicity (IC(50)s: approximately 0.5 microM) in CHO cells, which have an active polyamine transporter (PAT). However, this series had IC(50) values of >100 microM, 66.7 microM, and 15.5 microM, respectively, in CHO-MG cells, which are PAT-deficient. The observed lower cytotoxicity in the PAT-deficient CHO-MG cell line supported the premise that the conjugates use PAT for cellular entry. In general, moderate affinities for the polyamine transporter were observed for the N-arylmethyl 4,4-triamine series with their L1210 K(i) values all near 3 microM. In summary, the 4,4-triamine motif was shown to facilitate entry of polyamine conjugates into cells containing active polyamine transporters.

Effects of sow nutrition during gestation on within-litter birth weight variation: a review

“…The inhibition of placental polyamine synthesis is related to decreased placental size and lower fetal growth . Polyamines are organic compounds that are derived from ornithine by the arginase pathway, resulting in the synthesis of putrescine, spermidine and spermine (Lehninger et al, 1993;Wang et al, 2003). However, the polyamine synthesis in the porcine placenta is dependent on the conversion of arginine into ornithine and proline via the arginase pathway in other maternal tissues, as arginase activity is not detected in the maternal placenta (Wu et al, 2006).…”

The design of guanidinium-rich transporters and their internalization mechanisms

“…All exhibit similar function -high water solubility and rapid entry into cells -but they differ structurally in many significant respects except for the key conserved oligoguanidinium array. In addition to peptides, peptoids, and oligocarbamates, many other types of molecular transporters have been identified that cover a range of structural classes, including polyamines [5,6], polysaccharides During the past decade, many significant and exciting advances have been reported from our and other laboratories related to the mechanisms of uptake of GRTs and especially to their use in mediating cell and tissue uptake. An octaarginine transporter linked to Cyclosporin A has also been advanced to phase II clinical trials for dermatological applications [18] and a Tat 9-mer linked to a biologically active peptide cargo has been advanced clinically for the treatment of ischemia [19].…”

Real-time analysis of uptake and bioactivatable cleavage of luciferin-transporter conjugates in transgenic reporter mice

“…Many types of transporters have been reported in recent years including peptides (1)(2)(3)(4)(5), peptoids (6), polyamines (7,8), oligocarbamates (9), dendrimers (10,11), polysaccharides (12), steroids (13), cationic lipids (14,15), guanidinoglycosides (16), and even nanotubes (17). These transporters operate through a variety of mechanisms and some through multiple mechanisms depending on cell type, cargo, and other variables (5,(18)(19)(20)(21)(22).…”