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Photosensitizer-conjugated tryptophan-containing peptide ligands as new dual-targeted theranostics for cancers
Jisu Kim1, Jihyun Chae2, Jun Soo Kim2
1Molecular Imaging & Therapy Branch, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do 10408, Republic of Korea.
Abstract:
Here we report that new dual-targeted theranostic anti-cancer agents can be produced by simple conjugation of photosensitizers with tryptophan-containing peptide ligands via cyclic disulfide linkages. In the proof-of-concept study, photosensitizers conjugated with EGFR-targeting peptide GE11 (C-EGFR) were in close proximity with tryptophan residues in the conjugate, resulting in quenching of its fluorescence and singlet oxygen generation. C-EGFR specifically binds to target receptors on the cancer cell surface, after which it is internalized via receptor-mediated endocytosis. Intracellular cleavage of cyclic disulfide bonds allows separation of the photosensitizers from the tryptophan residue, after which they emit near-infrared (NIR) fluorescence and produce a phototoxic effect in the target cells. This strategy enabled us to accomplish simultaneous real-time NIR fluorescence imaging of EGFR-overexpressing cancer cells with high contrast and selective photodynamic therapy.
Insights
New dual-targeted theranostic agents combine photosensitizers and peptide ligands for cancer therapy. This approach enables simultaneous near-infrared fluorescence imaging and targeted photodynamic therapy of cancer cells.
Area of Science:
- Bioconjugation Chemistry
- Nanomedicine
- Cancer Theranostics
Background:
- Targeted cancer therapies require agents that can both image and treat tumors.
- Photosensitizers are key components in photodynamic therapy but often lack specific targeting.
- Epidermal Growth Factor Receptor (EGFR) is frequently overexpressed in various cancers, making it a viable therapeutic target.
Purpose of the Study:
- To develop novel dual-targeted theranostic agents for cancer treatment.
- To investigate the conjugation of photosensitizers with EGFR-targeting peptides via disulfide linkages.
- To evaluate the efficacy of these agents in simultaneous imaging and photodynamic therapy.
Main Methods:
- Conjugation of photosensitizers with tryptophan-containing peptide ligands (GE11) via cyclic disulfide bonds.
- Characterization of the conjugate (C-EGFR) for fluorescence quenching and singlet oxygen generation.
- In vitro studies involving EGFR-overexpressing cancer cells to assess targeting, internalization, and therapeutic effects.
- Evaluation of near-infrared (NIR) fluorescence imaging and photodynamic therapy efficacy.
Main Results:
- Successful synthesis of dual-targeted theranostic agents through simple conjugation.
- EGFR-targeting peptide (GE11) conjugated with photosensitizers showed quenched fluorescence and singlet oxygen production.
- Internalization of C-EGFR into cancer cells via receptor-mediated endocytosis was observed.
- Intracellular disulfide bond cleavage released photosensitizers, enabling NIR fluorescence emission and phototoxicity.
- Simultaneous real-time NIR fluorescence imaging and selective photodynamic therapy of EGFR-overexpressing cancer cells were achieved with high contrast.
Conclusions:
- The developed strategy provides a novel platform for creating dual-targeted theranostic agents.
- These agents effectively target cancer cells, enabling simultaneous imaging and photodynamic therapy.
- The approach holds promise for improved cancer diagnosis and treatment by combining imaging and therapeutic functions.
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