COX-2 inhibition alters the phenotype of tumor-associated macrophages from M2 to M1 in ApcMin/+ mouse polyps

Carcinogenesis. 2011 Sep;32(9):1333-9. doi: 10.1093/carcin/bgr128. Epub 2011 Jul 5.


Macrophages are a major component of tumor stroma. Tumor-associated macrophages (TAMs) show anti- (M1) or protumor (M2) functions depending on the cytokine milieu of the tumor microenvironment. Cyclooxygenase-2 (COX-2) is constitutively expressed in a variety of tumors including colorectal cancer. TAMs are known to be a major source of COX-2 in human and mice intestinal tumors. COX-2 inhibitor reduces the number and size of intestinal adenomas in familial adenomatous polyposis patients and Apc(Min/+) mice. Although COX-2 inhibitor is thought to regulate cancer-related inflammation, its effect on TAM phenotype remains unknown. Here, we examined the effects of COX-2 inhibition on TAM phenotype and cytokine expression both in vivo and in vitro. Firstly, the selective COX-2 inhibitor celecoxib changed the TAM phenotype from M2 to M1, in proportion to the reduction in number of Apc(Min/+) mouse polyps. Concomitantly, the expression of M1-related cytokine interfron (IFN)-γ was significantly upregulated by celecoxib, although the M2-related cytokines interleukin (IL)-4, IL-13 and IL-10 were not significantly altered. Secondly, IFN-γ treatment attenuated M2 phenotype of mouse peritoneal macrophages and oriented them to M1 even in the presence of M2-polarizing cytokines such as IL-4, IL-13 and IL-10. Thus, our results suggest that COX-2 inhibition alters TAM phenotype in an IFN-γ-dependent manner and subsequently may reduce intestinal tumor progression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Polarity
  • Cyclooxygenase 2 Inhibitors / pharmacology*
  • Cytokines / genetics
  • Female
  • Genes, APC
  • Interferon-gamma / pharmacology
  • Macrophage Activation
  • Macrophages / drug effects*
  • Macrophages / physiology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Neoplasms / immunology*
  • Phenotype
  • Th2 Cells / immunology


  • Cyclooxygenase 2 Inhibitors
  • Cytokines
  • Interferon-gamma