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Updated: Jul 14, 2026
In Vitro Assay to Study Tumor-macrophage Interaction
Published on: August 1, 2019
Analysis of gene expression in the tumor-associated macrophage
Michael D Duff1, Juan Mestre, Sirish Maddali
1Department of Surgery, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, New York, USA. mduff100@hotmail.com
Introduction:
The tumor-associated macrophage (TAM) is at the front line of the host's defense against malignancy and provides an attractive target for immune-modulatory therapy. However, factors present within the tumor microenvironment can alter macrophage phenotype, preventing its cytotoxic activity and reducing its susceptibility to interferon-gamma and lipopolysaccharide-mediated stimulation.
Methods:
Macrophages were isolated from subcutaneous B16 melanoma tumors implanted in C57 BL/6 mice. Wound macrophages were harvested from subcutaneously-implanted PVA sponges, and resting peritoneal macrophages were harvested by peritoneal lavage. Gene expression was analyzed using an Atlas cDNA array (Clontech, Mountain View, CA).
Results:
TAM demonstrated a pattern of gene expression distinct from both wound and peritoneal macrophage. There is an increase in proliferation-associated genes and in genes encoding the ultrastructural proteins cofillin, zyxin, and vimentin more commonly associated with fibroblast-like cells. In addition, an observed decrease in expression of the CD14 gene, and increase in inhibitory pathways including osteopontin and its receptor CD44, the inositol 1,4,5-triphosphate receptor, and the receptors for interleukin-4 and granulocyte monocyte-colony stimulating factor could explain the resistance of TAM to lipopolysaccharide-mediated stimulation. There was also a significant decrease in the expression of the interferon-gamma second messenger, IRF-1.
Conclusions:
This study has identified a number of pathways involved in the suppression of TAM function. Targeting of these pathways may allow for the generation of more effective immune-modulatory anti-neoplastic therapy.
Insights
Tumor-associated macrophages (TAMs) exhibit distinct gene expression patterns that hinder anti-cancer immunity. Targeting these suppressive pathways could lead to more effective cancer immunotherapies.
Area of Science:
- Immunology
- Cancer Biology
- Macrophage Biology
Background:
- Tumor-associated macrophages (TAMs) are crucial in anti-cancer defense but are often functionally suppressed within the tumor microenvironment.
- TAMs can be reprogrammed by tumor factors, losing cytotoxic activity and becoming resistant to immune stimulation.
Purpose of the Study:
- To investigate the distinct gene expression profile of TAMs compared to other macrophage populations.
- To identify molecular pathways contributing to TAM-mediated immune suppression.
Main Methods:
- Macrophages were isolated from B16 melanoma tumors, wound sites, and peritoneal cavities of C57 BL/6 mice.
- Gene expression analysis was performed using Atlas cDNA arrays.
Main Results:
- TAMs displayed unique gene expression, with increased proliferation-associated genes and fibroblast-like cell proteins (cofillin, zyxin, vimentin).
- Decreased CD14 expression and increased expression of inhibitory molecules (osteopontin, CD44, IL-4 receptors) were observed in TAMs.
- Reduced expression of interferon-gamma's second messenger, IRF-1, was noted in TAMs, explaining resistance to stimulation.
Conclusions:
- This study identified key pathways involved in TAM functional suppression.
- Targeting these identified pathways offers a potential strategy for developing enhanced cancer immunotherapies.
