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CCL2-CCR2 Axis Inhibition in Osteosarcoma Cell Model: The Impact of Oxygen Level on Cell Phenotype
Agne Petrosiute1, Justina Musvicaitė1, Donatas Petroška2
1Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania.
Abstract:
Treatment of osteosarcoma is hampered by tumor hypoxia and requires alternative approaches. Although the CCL2-CCR2 axis is indispensable in tumor-induced inflammation and angiogenesis, its blockade has not been effective to date. This study aimed to characterize how CCR2 inhibition affects the crosstalk of osteosarcoma cells with immune cells to better delineate tumor resistance mechanisms that help withstand such treatment. In this study, 143B cells were exposed to healthy donor PBMC supernatants in a transwell assay lacking direct cell-to-cell contact and subjected to different oxygen concentrations. In addition, mice bearing orthotopic 143B tumors were subjected to CCR2 antagonist treatment. Our findings show that hypoxic conditions alter cytokine and cancer- related protein expression on cells and impair CCR2 antagonist effects in the experimental osteosarcoma model. CCL2-CCR2 axis blockade in the 143B xenografts, which are positive for hypoxia marker CAIX, did not slow 143B tumor growth or metastasis but altered tumor microenvironment by VEGFR downregulation and shift in the CD44-positive cell population towards high CD44 expression. This study highlights differential responses of tumor cells to CCR2 antagonists in the presence of different oxygen saturations and expands our knowledge of compensatory mechanisms leading to CCL2-CCR2 treatment resistance.
Insights
Hypoxia hinders CCR2 antagonist treatment for osteosarcoma by altering cell communication and protein expression. This resistance mechanism involves compensatory pathways that limit treatment efficacy in hypoxic tumors.
Area of Science:
- Oncology
- Immunology
- Cancer Biology
Background:
- Osteosarcoma treatment faces challenges due to tumor hypoxia.
- The CCL2-CCR2 axis is crucial for tumor inflammation and angiogenesis but its blockade has shown limited success.
- Understanding resistance mechanisms to CCR2 inhibition is vital for developing effective therapies.
Purpose of the Study:
- To investigate how CCR2 inhibition impacts osteosarcoma cell interactions with immune cells under varying oxygen conditions.
- To identify tumor resistance mechanisms against CCR2 antagonist treatment.
- To explore the role of hypoxia in mediating treatment resistance.
Main Methods:
- In vitro studies using 143B osteosarcoma cells exposed to peripheral blood mononuclear cell (PBMC) supernatants under different oxygen concentrations.
- In vivo studies involving mice with orthotopic 143B tumors treated with a CCR2 antagonist.
- Analysis of cytokine and protein expression, hypoxia markers (CAIX), VEGFR, and CD44 expression.
Main Results:
- Hypoxic conditions altered cytokine and cancer-related protein expression in osteosarcoma cells.
- CCR2 antagonist treatment did not inhibit tumor growth or metastasis in hypoxic 143B xenografts.
- Treatment altered the tumor microenvironment, downregulating VEGFR and shifting CD44-positive cells towards high expression.
Conclusions:
- Hypoxia significantly impairs the efficacy of CCR2 antagonists in osteosarcoma models.
- Tumor cells exhibit differential responses to CCR2 antagonists based on oxygen saturation.
- Compensatory mechanisms in hypoxic tumors contribute to resistance against CCL2-CCR2 axis blockade.
