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Updated: Apr 27, 2026
Monitoring GPCR-β-arrestin1/2 Interactions in Real Time Living Systems to Accelerate Drug Discovery
Published on: June 28, 2019
Identifying bias in CCR1 antagonists using radiolabelled binding, receptor internalization, β-arrestin translocation
A Gilchrist1, T D Gauntner, A Fazzini
1Chicago College of Pharmacy, Midwestern University, Downers Grove, IL, USA.
Background And Purpose:
Investigators have suggested that the chemokine receptor CCR1 plays a role in multiple myeloma. Studies using antisense and neutralizing antibodies to CCR1 showed that down-regulation of the receptor altered disease progression in a mouse model. More recently, experiments utilizing scid mice injected with human myeloma cells demonstrated that the CCR1 antagonist BX471 reduced osteolytic lesions, while the CCR1 antagonist MLN-3897 prevented myeloma cell adhesion to osteoclasts. However, information is limited regarding the pharmacology of CCR1 antagonists in myeloma cells.
Experimental Approach:
We compared several well-studied CCR1 antagonists including AZD4818, BX471, CCX354, CP-481715, MLN-3897 and PS899877 for their ability to inhibit binding of [(125)I]-CCL3 in vitro using membranes prepared from RPMI 8226 cells, a human multiple myeloma cell line that endogenously expresses CCR1. In addition, antagonists were assessed for their ability to modulate CCL3-mediated internalization of CCR1 and CCL3-mediated cell migration using RPMI 8226 cells. As many GPCRs signal through β-arrestin-dependent pathways that are separate and distinct from those driven by G-proteins, we also evaluated the compounds for their ability to alter β-arrestin translocation.
Key Results:
There were clear differences between the CCR1 antagonists in their ability to inhibit CCL3 binding to myeloma cells, as well as in their ability to inhibit G-protein-dependent and -independent functional responses.
Conclusions And Implications:
Our studies demonstrate that tissue phenotype seems to be relevant with regards to CCR1. Moreover, it appears that for CCR1 antagonists, inhibition of β-arrestin translocation is not necessarily linked to chemotaxis or receptor internalization.
Insights
Chemokine receptor CCR1 antagonists show varied efficacy in multiple myeloma cells. Differences in inhibiting CCL3 binding and functional responses highlight the need for tailored therapeutic strategies against this cancer.
Area of Science:
- Immunology
- Pharmacology
- Oncology
Background:
- The chemokine receptor CCR1 is implicated in multiple myeloma progression.
- Previous studies showed CCR1 modulation affects disease in mouse models.
- CCR1 antagonists have shown potential in reducing myeloma-related bone lesions and cell adhesion.
Purpose of the Study:
- To investigate the pharmacology of various CCR1 antagonists in multiple myeloma cells.
- To compare the efficacy of different CCR1 antagonists in inhibiting ligand binding and downstream signaling.
Main Methods:
- Evaluated CCR1 antagonists (AZD4818, BX471, CCX354, CP-481715, MLN-3897, PS899877) for inhibiting [(125)I]-CCL3 binding in RPMI 8226 myeloma cells.
- Assessed antagonist effects on CCL3-mediated CCR1 internalization and cell migration.
- Determined the compounds' ability to modulate β-arrestin translocation.
Main Results:
- Significant differences were observed in the ability of CCR1 antagonists to inhibit CCL3 binding to myeloma cells.
- Antagonists varied in their effectiveness against G-protein-dependent and -independent functional responses.
- The compounds demonstrated distinct profiles in modulating receptor internalization, cell migration, and β-arrestin signaling.
Conclusions:
- Tissue phenotype appears relevant to CCR1 function in multiple myeloma.
- Inhibition of β-arrestin translocation by CCR1 antagonists is not consistently linked to chemotaxis or receptor internalization.
- These findings suggest distinct pharmacological profiles among CCR1 antagonists, impacting their potential therapeutic application.
