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Mechanisms and implications of dual-acting methotrexate in folate-targeted nanotherapeutic delivery.

Wong PT, Choi SK - Int J Mol Sci (2015)

Bottom Line: The rational design of a nanoplatform in drug delivery plays a crucial role in determining its targeting specificity and efficacy in vivo.A conventional approach relies on the surface conjugation of a nanometer-sized particle with two functionally distinct types of molecules, one as a targeting ligand, and the other as a therapeutic agent to be delivered to the diseased cell.However, an alternative simplified approach can be used, in which a single type of molecule displaying dual function as both a targeting ligand and therapeutic agent is conjugated to the nanoparticle.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, USA. ptw@med.umich.edu.

ABSTRACT
The rational design of a nanoplatform in drug delivery plays a crucial role in determining its targeting specificity and efficacy in vivo. A conventional approach relies on the surface conjugation of a nanometer-sized particle with two functionally distinct types of molecules, one as a targeting ligand, and the other as a therapeutic agent to be delivered to the diseased cell. However, an alternative simplified approach can be used, in which a single type of molecule displaying dual function as both a targeting ligand and therapeutic agent is conjugated to the nanoparticle. In this review, we evaluate the validity of this new strategy by using methotrexate, which displays multifunctional mechanisms of action. Methotrexate binds to the folate receptor, a surface biomarker frequently overexpressed in tumor cells, and also inhibits dihydrofolate reductase, an enzyme critical for cell survival and division. Thus we describe a series of fifth generation poly(amido amine) dendrimers conjugated with methotrexate, and discuss several lines of evidence supporting the efficacy of this new platform strategy based on surface plasmon resonance spectroscopy, enzyme activity assays, and cell-based studies with folate receptor (+) KB cancer cells.

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(A) Proposed schematic illustrating the concept of light-triggered MTX release; (B) In vitro cytotoxicity of G5(FA)9(MTX*)17 in FAR(+) KB cells, before (control; t = 0) and after UV irradiation (t = 6 or 14 min) [84]. MTX* = MTX linked with a photocleavable linker.
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ijms-16-01772-f007: (A) Proposed schematic illustrating the concept of light-triggered MTX release; (B) In vitro cytotoxicity of G5(FA)9(MTX*)17 in FAR(+) KB cells, before (control; t = 0) and after UV irradiation (t = 6 or 14 min) [84]. MTX* = MTX linked with a photocleavable linker.

Mentions: Second, we developed a novel strategy that would enable precise control of drug release in the cell [84,85]. In this strategy, a dendrimer, G5(FA9)(MTX*)17 which contains MTX attached with a photocleavable ortho-nitrobenzyl (ONB) linker that can be cleaved by exposure to UV light was used [84]. This allows controlled release of MTX molecules from the dendrimer by using a light trigger. This dendrimer was evaluated in FAR(+) KB cells for its cytotoxicity before and after UV light exposure. As summarized in Figure 7, each treatment condition showed dose-dependent cytotoxicity. Without light exposure (t = 0 min, control), a maximal 80% decrease in cell viability was observed relative to untreated cells. This potency is equivalent to an IC50 value of ~7 nM, indicating that this conjugate is approximately three-fold less potent than free MTX. Cytotoxicity measured following a 6 min exposure led to almost no change in the inhibition compared to no UV conditions. In a separate release study analyzed by HPLC, 6 min exposure was found to be sufficient for full MTX release, suggesting that the cytotoxicity before and after MTX release is almost identical [84]. However, a prolonged exposure (t = 14 min) decreased the activity (IC50 ≈ 15 nM) possibly as a result of partial degradation of MTX molecules, as suggested by HPLC analysis. In summary, the light-controlled drug release shows that the targeted delivery of active MTX can be achieved effectively with or without drug release.


Mechanisms and implications of dual-acting methotrexate in folate-targeted nanotherapeutic delivery.

Wong PT, Choi SK - Int J Mol Sci (2015)

(A) Proposed schematic illustrating the concept of light-triggered MTX release; (B) In vitro cytotoxicity of G5(FA)9(MTX*)17 in FAR(+) KB cells, before (control; t = 0) and after UV irradiation (t = 6 or 14 min) [84]. MTX* = MTX linked with a photocleavable linker.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4307333&req=5

ijms-16-01772-f007: (A) Proposed schematic illustrating the concept of light-triggered MTX release; (B) In vitro cytotoxicity of G5(FA)9(MTX*)17 in FAR(+) KB cells, before (control; t = 0) and after UV irradiation (t = 6 or 14 min) [84]. MTX* = MTX linked with a photocleavable linker.
Mentions: Second, we developed a novel strategy that would enable precise control of drug release in the cell [84,85]. In this strategy, a dendrimer, G5(FA9)(MTX*)17 which contains MTX attached with a photocleavable ortho-nitrobenzyl (ONB) linker that can be cleaved by exposure to UV light was used [84]. This allows controlled release of MTX molecules from the dendrimer by using a light trigger. This dendrimer was evaluated in FAR(+) KB cells for its cytotoxicity before and after UV light exposure. As summarized in Figure 7, each treatment condition showed dose-dependent cytotoxicity. Without light exposure (t = 0 min, control), a maximal 80% decrease in cell viability was observed relative to untreated cells. This potency is equivalent to an IC50 value of ~7 nM, indicating that this conjugate is approximately three-fold less potent than free MTX. Cytotoxicity measured following a 6 min exposure led to almost no change in the inhibition compared to no UV conditions. In a separate release study analyzed by HPLC, 6 min exposure was found to be sufficient for full MTX release, suggesting that the cytotoxicity before and after MTX release is almost identical [84]. However, a prolonged exposure (t = 14 min) decreased the activity (IC50 ≈ 15 nM) possibly as a result of partial degradation of MTX molecules, as suggested by HPLC analysis. In summary, the light-controlled drug release shows that the targeted delivery of active MTX can be achieved effectively with or without drug release.

Bottom Line: The rational design of a nanoplatform in drug delivery plays a crucial role in determining its targeting specificity and efficacy in vivo.A conventional approach relies on the surface conjugation of a nanometer-sized particle with two functionally distinct types of molecules, one as a targeting ligand, and the other as a therapeutic agent to be delivered to the diseased cell.However, an alternative simplified approach can be used, in which a single type of molecule displaying dual function as both a targeting ligand and therapeutic agent is conjugated to the nanoparticle.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, USA. ptw@med.umich.edu.

ABSTRACT
The rational design of a nanoplatform in drug delivery plays a crucial role in determining its targeting specificity and efficacy in vivo. A conventional approach relies on the surface conjugation of a nanometer-sized particle with two functionally distinct types of molecules, one as a targeting ligand, and the other as a therapeutic agent to be delivered to the diseased cell. However, an alternative simplified approach can be used, in which a single type of molecule displaying dual function as both a targeting ligand and therapeutic agent is conjugated to the nanoparticle. In this review, we evaluate the validity of this new strategy by using methotrexate, which displays multifunctional mechanisms of action. Methotrexate binds to the folate receptor, a surface biomarker frequently overexpressed in tumor cells, and also inhibits dihydrofolate reductase, an enzyme critical for cell survival and division. Thus we describe a series of fifth generation poly(amido amine) dendrimers conjugated with methotrexate, and discuss several lines of evidence supporting the efficacy of this new platform strategy based on surface plasmon resonance spectroscopy, enzyme activity assays, and cell-based studies with folate receptor (+) KB cancer cells.

Show MeSH
Related in: MedlinePlus