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Preparation and Characterization of an Engineered FGF1 Conjugated to 161Tb for Targeting of FGFRs
Linlin Song1,2, Michal Kostas1,2, Jon K Laerdahl3,4
1Department of Tumor Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, Oslo 0379, Norway.
Abstract:
The fibroblast growth factor receptor family members, FGFR1-4, are frequently overexpressed in various solid tumors, including breast cancer and sarcomas. This overexpression highlights the potential of the family of FGFRs as promising targets for cancer therapy. However, conventional FGFR kinase inhibitors often encounter challenges such as limited efficacy or drug resistance. In this study, we pursue an alternative strategy by designing a conjugate of the FGFR ligand FGF1 with the radioisotope 161Tb, for targeted therapy in FGFR-overexpressing cancer cells. FGF1 was engineered (eFGF1) to incorporate a single cysteine at the C terminus for site-specific labeling with a DOTA chelator. eFGF1-DOTA was mixed with the radioisotope 161Tb under mild conditions, resulting in a labeling efficiency above 90%. The nonradioactive ligands were characterized by mass spectrometry, while radioligands were characterized by thin-layer chromatography. The targeting function of the radioligands was assessed through confocal microscopy, flow cytometry, and Western blot analysis, focusing on binding to cancer cells and the activation of downstream signaling pathways related to FGFR. When compared to MCF-7 and RD cell lines with low FGFR expression, eFGF1-DOTA-Tb[161Tb] radioligands demonstrated significantly higher accumulation in FGFR-overexpressing cell lines (MCF-7 FGFR1 and RMS559), leading to enhanced cytotoxicity. Besides radionuclides, eFGF1 can also deliver doxorubicin (DOX) into cancer cells. Considering these characteristics, eFGF1-DOTA-Tb[161Tb] and eFGF1-DOX emerge as promising candidates for FGFR-targeted cancer therapy, and further evaluation in vivo is warranted.
Insights
This study developed a targeted cancer therapy using a fibroblast growth factor receptor (FGFR) ligand conjugated with the radioisotope 161Tb. This novel radioligand effectively targets FGFR-overexpressing cancer cells, showing enhanced cytotoxicity and promising potential for cancer treatment.
Area of Science:
- Oncology
- Radiochemistry
- Molecular Biology
Background:
- Fibroblast growth factor receptors (FGFRs) are overexpressed in several solid tumors, presenting them as potential therapeutic targets.
- Conventional FGFR kinase inhibitors face challenges like limited efficacy and drug resistance.
- Targeted delivery of therapeutic agents to FGFR-overexpressing cancer cells is an alternative strategy.
Purpose of the Study:
- To design and evaluate a novel FGFR-targeted therapy using a conjugate of the FGFR ligand FGF1 with the radioisotope 161Tb.
- To assess the efficacy of this radioligand in delivering therapeutic payload to FGFR-overexpressing cancer cells.
- To explore the potential of engineered FGF1 (eFGF1) for targeted cancer treatment.
Main Methods:
- Engineered FGF1 (eFGF1) with site-specific labeling capability using a DOTA chelator.
- Site-specific radiolabeling of eFGF1-DOTA with 161Tb.
- Characterization of radioligands using mass spectrometry and thin-layer chromatography.
- Assessment of targeting and downstream signaling activation in cancer cells via confocal microscopy, flow cytometry, and Western blot.
Main Results:
- High labeling efficiency (>90%) achieved for eFGF1-DOTA-Tb[161Tb].
- Radioligands showed significantly higher accumulation in FGFR-overexpressing cell lines (MCF-7 FGFR1 and RMS559) compared to low-expression lines.
- Enhanced cytotoxicity observed in FGFR-overexpressing cells treated with eFGF1-DOTA-Tb[161Tb].
- eFGF1 demonstrated potential for delivering doxorubicin (DOX) as well.
Conclusions:
- eFGF1-DOTA-Tb[161Tb] is a promising radioligand for targeted therapy in FGFR-overexpressing cancers.
- The engineered FGF1 ligand shows versatility for delivering both radionuclides and chemotherapeutics.
- Further in vivo evaluation is warranted to confirm the therapeutic potential of these conjugates.
