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A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators
Published on: February 20, 2018
Identification of A2BAR as a potential target in colorectal cancer using novel fluorescent GPCR ligands
Jorge Barbazán1, Maria Majellaro2, Antón L Martínez3
1Translational Medical Oncology Group (ONCOMET), Health Research Institute of Santiago de Compostela (IDIS), University Hospital of Santiago de Compostela (SERGAS), Trav. Choupana s/n, 15706 Santiago de Compostela, Spain.
Abstract:
G-protein coupled receptors (GPCRs) have been largely targeted in a wide range of diseases, but few therapies have been directed against GPCRs in the field of cancer, partly because of the lack of effective target identification strategies. Here, using colorectal cancer (CRC) as a model, we explored the gene expression of a panel of GPCRs in tumor and stromal cells, identifying specific gene sets defining each cellular compartment. We selected the adenosine receptor 2B (A2BAR), specifically expressed in cancer cell lines compared with stromal cells, to explore the use of fluorescent ligands that can be used for target visualization. Fluorescent probes allowed semi-quantitative receptor mapping in living cells and validated the specific expression of A2BAR in CRC cell lines. As well, fluorescent ligands were effective at monitoring real-time A2BAR receptor labeling using live-imaging modalities, and displayed high efficiency when used to label complex 3D cellular systems such as tumor spheroids. Finally, we validated A2BAR as a potential pharmacological tool in CRC, using selective antagonists, finding a reduction in tumor cell proliferation. This proof-of-concept study suggests the use of fluorescent ligands for GPCR characterization through imaging, and as possible new tools used for target validation in drug screening methodologies.
Insights
Researchers developed fluorescent probes to visualize G-protein coupled receptors (GPCRs) in colorectal cancer (CRC). This method identified the adenosine receptor 2B (A2BAR) as a potential drug target, showing reduced tumor cell proliferation with antagonists.
Area of Science:
- Oncology
- Pharmacology
- Molecular Biology
Background:
- G-protein coupled receptors (GPCRs) are crucial drug targets, yet their role in cancer therapy remains underexplored due to limited target identification strategies.
- Colorectal cancer (CRC) presents an opportunity to investigate GPCRs as therapeutic targets.
- Effective methods for GPCR target identification and validation in cancer are needed.
Purpose of the Study:
- To explore GPCR gene expression in colorectal cancer (CRC) tumor and stromal cells.
- To identify specific GPCRs for cancer therapy, focusing on the adenosine receptor 2B (A2BAR).
- To evaluate the utility of fluorescent ligands for GPCR visualization and drug screening in CRC.
Main Methods:
- Gene expression profiling of GPCRs in CRC tumor and stromal cells.
- Utilizing fluorescent probes and live-imaging to visualize and map A2BAR expression in cancer cells and 3D tumor spheroids.
- Employing selective A2BAR antagonists to assess therapeutic effects on tumor cell proliferation.
Main Results:
- Identified distinct GPCR gene expression profiles in CRC tumor versus stromal cells.
- Validated A2BAR as specifically expressed in CRC cell lines using fluorescent ligands.
- Demonstrated real-time monitoring of A2BAR labeling and effective visualization in complex 3D models.
- Showed that A2BAR antagonists reduce CRC tumor cell proliferation, confirming A2BAR as a viable drug target.
Conclusions:
- Fluorescent ligands are effective tools for GPCR characterization and imaging in cancer research.
- A2BAR is a promising therapeutic target in colorectal cancer.
- This approach offers a novel strategy for GPCR target validation in drug discovery and screening methodologies.
