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

Glutathione content in response to Ant 4 treatmentHL-60 cells were seeded at 6.8×104 cells/ml in 3.5-cm plates and grown for up to 144 h. After 48 h, cells were treated with vehicle (open bars) or 15 μM Ant 4 (closed bars). Duplicate plates were then harvested every 24 h. Glutathione was extracted in 0.2 M PCA and stored at −20 °C until its measurement. Results shown are the means±S.E.M. (n=3) with two replicates per experiment. Results were analysed statistically using ANOVA with Bonferroni's multiple comparison post-hoc test (*P<0.05; **P<0.001).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Glutathione content in response to Ant 4 treatmentHL-60 cells were seeded at 6.8×104 cells/ml in 3.5-cm plates and grown for up to 144 h. After 48 h, cells were treated with vehicle (open bars) or 15 μM Ant 4 (closed bars). Duplicate plates were then harvested every 24 h. Glutathione was extracted in 0.2 M PCA and stored at −20 °C until its measurement. Results shown are the means±S.E.M. (n=3) with two replicates per experiment. Results were analysed statistically using ANOVA with Bonferroni's multiple comparison post-hoc test (*P<0.05; **P<0.001).

Mentions: In response to Ant 4 treatment, HL-60 cells showed a hugely significant decrease in glutathione content compared with the controls at each 24 h time point after addition of Ant 4 (Figure 6). These decreases were 70.6% at 24 h (P<0.001), 65.8% at 48 h (P<0.05), 60.0% at 72 h (P<0.05) and 80.1% at 96 h (P<0.05). Furthermore, after 48 h exposure to Ant 4 there was over a 3-fold increase in the DNA damage compared with the controls (P< 0.01) (results not shown). Consistent with observations in our laboratory (A.V. Fraser and H.M. Wallace, unpublished work), the glutathione content of the controls decreased with increasing time in culture.


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

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

Glutathione content in response to Ant 4 treatmentHL-60 cells were seeded at 6.8×104 cells/ml in 3.5-cm plates and grown for up to 144 h. After 48 h, cells were treated with vehicle (open bars) or 15 μM Ant 4 (closed bars). Duplicate plates were then harvested every 24 h. Glutathione was extracted in 0.2 M PCA and stored at −20 °C until its measurement. Results shown are the means±S.E.M. (n=3) with two replicates per experiment. Results were analysed statistically using ANOVA with Bonferroni's multiple comparison post-hoc test (*P<0.05; **P<0.001).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Glutathione content in response to Ant 4 treatmentHL-60 cells were seeded at 6.8×104 cells/ml in 3.5-cm plates and grown for up to 144 h. After 48 h, cells were treated with vehicle (open bars) or 15 μM Ant 4 (closed bars). Duplicate plates were then harvested every 24 h. Glutathione was extracted in 0.2 M PCA and stored at −20 °C until its measurement. Results shown are the means±S.E.M. (n=3) with two replicates per experiment. Results were analysed statistically using ANOVA with Bonferroni's multiple comparison post-hoc test (*P<0.05; **P<0.001).
Mentions: In response to Ant 4 treatment, HL-60 cells showed a hugely significant decrease in glutathione content compared with the controls at each 24 h time point after addition of Ant 4 (Figure 6). These decreases were 70.6% at 24 h (P<0.001), 65.8% at 48 h (P<0.05), 60.0% at 72 h (P<0.05) and 80.1% at 96 h (P<0.05). Furthermore, after 48 h exposure to Ant 4 there was over a 3-fold increase in the DNA damage compared with the controls (P< 0.01) (results not shown). Consistent with observations in our laboratory (A.V. Fraser and H.M. Wallace, unpublished work), the glutathione content of the controls decreased with increasing time in culture.

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