Limits...
A putrescine-anthracene conjugate: a paradigm for selective drug delivery.

Palmer AJ, Ghani RA, Kaur N, Phanstiel O, Wallace HM - Biochem. J. (2009)

Bottom Line: Apoptosis was the predominant type of cell death, with mechanistic studies revealing that oxidative stress and DNA damage may have a part to play.For the first time, uptake of Ant 4 via the PTS was demonstrated both directly and indirectly in human cell lines.In addition, Ant 4 significantly reduced putrescine uptake, demonstrating that this conjugate not only used the PTS, but also could successfully compete with its native polyamine for uptake.

View Article: PubMed Central - PubMed

Affiliation: Divison of Applied Medicine, School of Medicine and Dentistry, University of Aberdeen, Aberdeen AB25 2ZD, UK.

ABSTRACT
Increased polyamine concentrations play an important role in the development of cancer at all stages, from initiation through to maintenance of the transformed phenotype. One way cancer cells accumulate increased concentrations of polyamines is by increased uptake of preformed polyamines via their PTS (polyamine transport system). The PTS is promiscuous and will transport a range of polyamine-based molecules. Therefore it may be that cytotoxic drugs could be attached to polyamine vectors and targeted selectively to cancer cells by utilizing the PTS. The aim of the present study was to investigate the potential of Ant 4, a putrescine-anthracene conjugate, to target cytotoxic agents to human cancer cells as a paradigm for a novel method of selective drug delivery. Ant 4 induced cytotoxicity after only 24 h exposure. Apoptosis was the predominant type of cell death, with mechanistic studies revealing that oxidative stress and DNA damage may have a part to play. For the first time, uptake of Ant 4 via the PTS was demonstrated both directly and indirectly in human cell lines. In addition, Ant 4 significantly reduced putrescine uptake, demonstrating that this conjugate not only used the PTS, but also could successfully compete with its native polyamine for uptake. However, the most interesting finding was the intracellular depletion of the polyamine pools, providing an additional mode of toxicity for Ant 4 and the possibility that this molecule may act as a 'double-edged sword': preventing cell growth by delivery of the toxic moiety and by depletion of intracellular polyamine content.

Show MeSH

Related in: MedlinePlus

Putrescine uptake in response to Ant 4HL-60 cells were seeded at 6.8×104 cells/ml on 24-well plates for 48 h. After this time, cells were incubated with [14C]putrescine for 10, 20, 30 and 60 min with (•) or without (■) 15 μM Ant 4. Plates were harvested at the appropriate timepoint and the polyamine fraction extracted in 0.2 M PCA. Samples were then analysed using a Canberra Packard 1900A scintillation spectrophotometer for 10 min or 10000 counts, with a 2% error. Results shown are the means±S.E.M. (n=3) with three replicates per experiment. Results were analysed statistically using ANOVA with Bonferroni's multiple comparison post-hoc test (*P<0.001).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2805923&req=5

Figure 5: Putrescine uptake in response to Ant 4HL-60 cells were seeded at 6.8×104 cells/ml on 24-well plates for 48 h. After this time, cells were incubated with [14C]putrescine for 10, 20, 30 and 60 min with (•) or without (■) 15 μM Ant 4. Plates were harvested at the appropriate timepoint and the polyamine fraction extracted in 0.2 M PCA. Samples were then analysed using a Canberra Packard 1900A scintillation spectrophotometer for 10 min or 10000 counts, with a 2% error. Results shown are the means±S.E.M. (n=3) with three replicates per experiment. Results were analysed statistically using ANOVA with Bonferroni's multiple comparison post-hoc test (*P<0.001).

Mentions: To provide further evidence that Ant 4 utilized the PTS in the HL-60 cell line, uptake studies were conducted. Uptake of [14C]putrescine was significantly reduced by Ant 4 at 10 (P<0.0.001), 20 (P<0.001), 30 (P<0.001) and 60 (P<0.001) min (Figure 5). This result suggests that Ant 4 successfully competes with putrescine for the PTS in the HL-60 cell line. Furthermore, Ant 4 had no inhibitory effect on spermidine or spermine uptake (results not shown), suggesting that in the HL-60 cell line, different transporters exist for the transport of the individual polyamines.


A putrescine-anthracene conjugate: a paradigm for selective drug delivery.

Palmer AJ, Ghani RA, Kaur N, Phanstiel O, Wallace HM - Biochem. J. (2009)

Putrescine uptake in response to Ant 4HL-60 cells were seeded at 6.8×104 cells/ml on 24-well plates for 48 h. After this time, cells were incubated with [14C]putrescine for 10, 20, 30 and 60 min with (•) or without (■) 15 μM Ant 4. Plates were harvested at the appropriate timepoint and the polyamine fraction extracted in 0.2 M PCA. Samples were then analysed using a Canberra Packard 1900A scintillation spectrophotometer for 10 min or 10000 counts, with a 2% error. Results shown are the means±S.E.M. (n=3) with three replicates per experiment. Results were analysed statistically using ANOVA with Bonferroni's multiple comparison post-hoc test (*P<0.001).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2805923&req=5

Figure 5: Putrescine uptake in response to Ant 4HL-60 cells were seeded at 6.8×104 cells/ml on 24-well plates for 48 h. After this time, cells were incubated with [14C]putrescine for 10, 20, 30 and 60 min with (•) or without (■) 15 μM Ant 4. Plates were harvested at the appropriate timepoint and the polyamine fraction extracted in 0.2 M PCA. Samples were then analysed using a Canberra Packard 1900A scintillation spectrophotometer for 10 min or 10000 counts, with a 2% error. Results shown are the means±S.E.M. (n=3) with three replicates per experiment. Results were analysed statistically using ANOVA with Bonferroni's multiple comparison post-hoc test (*P<0.001).
Mentions: To provide further evidence that Ant 4 utilized the PTS in the HL-60 cell line, uptake studies were conducted. Uptake of [14C]putrescine was significantly reduced by Ant 4 at 10 (P<0.0.001), 20 (P<0.001), 30 (P<0.001) and 60 (P<0.001) min (Figure 5). This result suggests that Ant 4 successfully competes with putrescine for the PTS in the HL-60 cell line. Furthermore, Ant 4 had no inhibitory effect on spermidine or spermine uptake (results not shown), suggesting that in the HL-60 cell line, different transporters exist for the transport of the individual polyamines.

Bottom Line: Apoptosis was the predominant type of cell death, with mechanistic studies revealing that oxidative stress and DNA damage may have a part to play.For the first time, uptake of Ant 4 via the PTS was demonstrated both directly and indirectly in human cell lines.In addition, Ant 4 significantly reduced putrescine uptake, demonstrating that this conjugate not only used the PTS, but also could successfully compete with its native polyamine for uptake.

View Article: PubMed Central - PubMed

Affiliation: Divison of Applied Medicine, School of Medicine and Dentistry, University of Aberdeen, Aberdeen AB25 2ZD, UK.

ABSTRACT
Increased polyamine concentrations play an important role in the development of cancer at all stages, from initiation through to maintenance of the transformed phenotype. One way cancer cells accumulate increased concentrations of polyamines is by increased uptake of preformed polyamines via their PTS (polyamine transport system). The PTS is promiscuous and will transport a range of polyamine-based molecules. Therefore it may be that cytotoxic drugs could be attached to polyamine vectors and targeted selectively to cancer cells by utilizing the PTS. The aim of the present study was to investigate the potential of Ant 4, a putrescine-anthracene conjugate, to target cytotoxic agents to human cancer cells as a paradigm for a novel method of selective drug delivery. Ant 4 induced cytotoxicity after only 24 h exposure. Apoptosis was the predominant type of cell death, with mechanistic studies revealing that oxidative stress and DNA damage may have a part to play. For the first time, uptake of Ant 4 via the PTS was demonstrated both directly and indirectly in human cell lines. In addition, Ant 4 significantly reduced putrescine uptake, demonstrating that this conjugate not only used the PTS, but also could successfully compete with its native polyamine for uptake. However, the most interesting finding was the intracellular depletion of the polyamine pools, providing an additional mode of toxicity for Ant 4 and the possibility that this molecule may act as a 'double-edged sword': preventing cell growth by delivery of the toxic moiety and by depletion of intracellular polyamine content.

Show MeSH
Related in: MedlinePlus