title: Interleukin-4 Expressed By Neoplastic Cells Provokes an Anti-Metastatic Myeloid Immune Response.
abstract: OBJECTIVE
  Interleukin-4 (IL-4) can induce macrophages to undergo alternative activation and polarize toward an M2-like or wound healing phenotype. Tumor associated macrophages (TAMs) are thought to assume M2-like properties, and it has been suggested they promote tumor growth and metastasis through effects on the tumor stroma, including extracelluar matrix remodeling and angiogenesis. IL-4 also promotes macrophage survival and formation of multinucleated giant cells, which have enhanced phagocytic behavior. This study was designed to explore the effect of cancer cell derived IL-4 on the tumor immune stroma and metastasis.
  
  
  METHODS
  The metastatic mouse mammary carcinoma cell line AC2M2 was transduced with control or IL-4 encoding retroviruses and employed in orthotopic engraftment models. Tumor growth and metastasis were assessed. The cellular composition and biomarker expression of tumors were examined by immunohistochemical staining and flow cytometry; the transcriptome of the immune stroma was analyzed by nanoString based transcript quantitation; andin vivoandin vitrointeractions between cancer cells and macrophages were assessed by flow cytometry and co-culture with video-time lapse microscopy, respectively.
  
  
  RESULTS
  Unexpectedly, tumors from IL-4 expressing AC2M2 engrafted cells grew at reduced rates, and most surprising, they lost all metastatic potential relative to tumors from control AC2M2 cells. Myeloid cell numbers were not increased in IL-4 expressing tumors, but their expression of the M2 marker arginase I was elevated. Transcriptome analysis revealed an immune signature consistent with IL-4 induced M2 polarization of the tumor microenvironment and a generalized increase in myeloid involvement in the tumor stroma. Flow cytometry analysis indicated enhanced cancer cell phagocytosis by TAMs from IL-4 expressing tumors, and co-culture studies showed that IL-4 expressing cancer cells supported the survival and promoted thein vitrophagocytic behavior of macrophages.
  
  
  CONCLUSIONS
  Although M2-like TAMs have been linked to enhanced tumorigenesis, this study shows that IL-4 production by cancer cells is associated with suppressed tumor growth and loss of metastatic potential as well as enhanced phagocytic behavior of TAMs.
authors: Department of Pathology and Molecular Medicine, Queen's University, Division of Cancer Biology and Genetics, Cancer Research Institute, Kingston, Ontario, K7L 3N6, Canada.
authors: Connie S
authors: CS
authors: Zhang
authors: Department of Pathology and Molecular Medicine, Queen's University, Division of Cancer Biology and Genetics, Cancer Research Institute, Kingston, Ontario, K7L 3N6, Canada.
authors: Hyeyeon
authors: H
authors: Kim
authors: Department of Pathology and Molecular Medicine, Queen's University, Division of Cancer Biology and Genetics, Cancer Research Institute, Kingston, Ontario, K7L 3N6, Canada.
authors: Graeme
authors: G
authors: Mullins
authors: Department of Pathology and Molecular Medicine, Queen's University, Division of Cancer Biology and Genetics, Cancer Research Institute, Kingston, Ontario, K7L 3N6, Canada.
authors: Kathrin
authors: K
authors: Tyryshkin
authors: Department of Pathology and Molecular Medicine, Queen's University, Division of Cancer Biology and Genetics, Cancer Research Institute, Kingston, Ontario, K7L 3N6, Canada.
authors: David P
authors: DP
authors: LeBrun
authors: Department of Pathology and Molecular Medicine, Queen's University, Division of Cancer Biology and Genetics, Cancer Research Institute, Kingston, Ontario, K7L 3N6, Canada.
authors: Bruce E
authors: BE
authors: Elliott
authors: Department of Pathology and Molecular Medicine, Queen's University, Division of Cancer Biology and Genetics, Cancer Research Institute, Kingston, Ontario, K7L 3N6, Canada.
authors: Peter A
authors: PA
authors: Greer
keywords: Interleukin-4; M2 polarization; Metastasis; Orthotopic engraftment; Tumor associated macrophages