ABSTRACT
Tumor-associated macrophages (TAMs) are known to be involved in the progression, angiogenesis, and motility of various cancers. We previously reported the association between an increased number of infiltrating TAMs with tumor progression and poor prognosis in esophageal squamous cell carcinomas (ESCCs). To study the roles of TAMs in ESCC, we first exposed peripheral blood monocyte (PBMo)-derived macrophages from healthy volunteers to conditioned media of TE series human ESCC cell line (TECM) and confirmed the induction of the expression of the M2 macrophage marker CD204 and the protumorigenic factors interleukin (IL)-10, VEGFA, and MMPs. Next, we compared gene expression profiles between PBMo-derived macrophages stimulated with or without TECM by cDNA microarray and focused on growth differentiation factor 15 (GDF15) among the highly expressed genes including IL-6, IL-8, and CXCL1. Our immunohistochemical study of 70 surgically resected ESCCs revealed that GDF15 was present not only in cancer cells but also in macrophages. The high expression of GDF15 in the ESCCs was significantly correlated with several more malignant phenotypes including vessel invasion, lymph node metastasis, and clinical stages. Patients with high GDF15 expression showed significantly poorer disease-free survival (P=0.011) and overall survival (P=0.041). We also found that recombinant human GDF15 promotes cell proliferation and the phosphorylation of both Akt and Erk1/2 in ESCC cell lines in vitro. These results indicate that GDF15 is secreted by both TAMs and cancer cells in the tumor microenvironment and is associated with aberrant growth and a poor prognosis in human ESCC.
Subject(s)
Carcinoma, Squamous Cell/metabolism , Esophageal Neoplasms/metabolism , Growth Differentiation Factor 15/metabolism , Growth Differentiation Factor 15/pharmacology , MAP Kinase Signaling System/drug effects , Macrophages/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Culture Media, Conditioned/chemistry , Culture Media, Conditioned/metabolism , Culture Media, Conditioned/pharmacology , Cytokines/metabolism , Esophageal Squamous Cell Carcinoma , Growth Differentiation Factor 15/genetics , Humans , Leukocytes, Mononuclear/drug effects , Leukocytes, Mononuclear/metabolism , Phosphorylation/drug effects , Tumor Microenvironment/physiologyABSTRACT
Tumor-associated macrophages (TAMs) are known to be involved in the progression of various human malignancies. We previously demonstrated that CD204 was a useful marker for TAMs contributing to the angiogenesis, progression, and prognosis of human esophageal squamous cell carcinoma (ESCC). We also showed that conditioned media of ESCC cell lines induced CD204 expression in THP-1 human monocytic leukemia cells. Here, we performed a cDNA microarray analysis between THP-1 cells stimulated with TPA (macrophage [MΦ]-like THP-1 cells) treated with and without conditioned medium of ESCC cell line to clarify the molecular characteristics of TAMs in ESCC. From the microarray data, we discovered that Cyr61 was induced in CD204-positive-differentiated THP-1 cells (TAM-like THP-1 cells). In the ESCC microenvironment, not only cancer cells but also TAMs expressed Cyr61. Interestingly, the expression levels of Cyr61 showed a significant positive correlation with the number of CD204-positive macrophages in ESCCs by immunohistochemistry. Recombinant human Cyr61 (rhCyr61) promoted cell migration and induced the expression of CD204 along with the activation of the MEK/ERK pathway in MΦ-like THP-1 cells. Pretreatment with a MEK1/2 inhibitor significantly inhibited not only the Cyr61-mediated migration but also the CD204 expression in the MΦ-like THP-1 cells. These results suggest that Cyr61 may contribute to the expression of CD204 and the promotion of cell migration via the MEK/ERK pathway in TAMs in the ESCC microenvironment.