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Novel peptide conjugates for tumor-specific chemotherapy
M Langer1, F Kratz, B Rothen-Rutishauser
1Institute of Biochemistry, University of Leipzig, Talstrasse 33, D-04103 Leipzig, Germany.
Abstract:
One of the major problems in cancer chemotherapy are the severe side effects that limit the dose of the anticancer drugs because of their unselectivity for tumor versus normal cells. In the present work, we show that coupling of anthracyclines to peptides is a promising approach to obtain selectivity. The peptide-drug conjugate was designed to bind to specific receptors expressed on the tumor cells with subsequent internalization of the ligand-receptor complex. Neuropeptide Y (NPY), a 36-amino acid peptide of the pancreatic polypeptide family, was chosen as model peptide because NPY receptors are overexpressed in a number of neuroblastoma tumors and the thereof derived cell lines. Daunorubicin and doxorubicin, two widely used antineoplastic agents in tumor therapy, were covalently linked to NPY via two spacers that differ in stability: an acid-sensitive hydrazone bond at the 13-keto position of daunorubicin and a stable amide bond at the 3'-amino position of daunorubicin and doxorubicin. Receptor binding of these three conjugates ([C(15)]-NPY-Dauno-HYD, [C(15)]-NPY-Dauno-MBS, and [C(15)]-NPY-Doxo-MBS) was determined at the human neuroblastoma cell line SK-N-MC, which selectively expresses the NPY Y(1) receptor subtype, and cytotoxic activity was evaluated using a XTT-based colorimetric cellular cytotoxicity assay. The different conjugates were able to bind to the receptor with affinities ranging from 25 to 51 nM, but only the compound containing the acid-sensitive bond ([C(15)]-NPY-Dauno-HYD) showed cytotoxic activity comparable to the free daunorubicin. This cytotoxicity is Y(1) receptor-mediated as shown in blocking studies with BIBP 3226, because tumor cells that do not express NPY receptors were sensitive to free daunorubicin, but not to the peptide-drug conjugate. The intracellular distribution was investigated by confocal laser scanning microscopy. We found evidence that the active conjugate [C(15)]-NPY-Dauno-HYD releases daunorubicin, which is localized close to the nucleus, whereas the inactive conjugate [C(15)]-NPY-Dauno-MBS is distributed distantly from the nucleus and does not seem to release the drug within the cell.
Insights
Coupling anticancer drugs to peptides like Neuropeptide Y (NPY) offers a promising strategy for targeted cancer chemotherapy. An acid-sensitive conjugate demonstrated selective tumor cell killing by releasing daunorubicin near the nucleus.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Cancer chemotherapy faces limitations due to severe side effects from unselective drug distribution.
- Targeted drug delivery aims to improve anticancer agent efficacy by selectively targeting tumor cells.
Purpose of the Study:
- To investigate the potential of peptide-drug conjugates for selective cancer chemotherapy.
- To design and evaluate Neuropeptide Y (NPY)-anthracycline conjugates for neuroblastoma treatment.
Main Methods:
- Synthesized three NPY-anthracycline conjugates with varying linker stability (acid-sensitive hydrazone and stable amide bonds).
- Assessed receptor binding affinity using the human neuroblastoma cell line SK-N-MC (NPY Y(1) receptor subtype).
- Evaluated cytotoxic activity via XTT assay and intracellular drug localization using confocal microscopy.
Main Results:
- All conjugates exhibited receptor binding affinities between 25-51 nM.
- Only the conjugate with the acid-sensitive hydrazone bond ([C(15)]-NPY-Dauno-HYD) displayed significant cytotoxic activity comparable to free daunorubicin.
- Cytotoxicity was confirmed as NPY Y(1) receptor-mediated, with the active conjugate releasing daunorubicin near the nucleus.
Conclusions:
- Peptide-drug conjugates, particularly those with acid-sensitive linkers, represent a viable approach for targeted cancer therapy.
- The NPY-daunorubicin conjugate with a hydrazone linker shows promise for selective neuroblastoma treatment by enabling targeted drug release.
- Understanding intracellular drug localization is crucial for optimizing the design of effective peptide-drug conjugates.