Abstract 730: The roles of FGF-2-NCAMFGFR1 interplay in esophageal squamous cell carcinomas and its microenvironment including tumor-associated macrophages

Tumor-associated macrophages (TAMs) have important roles in the angiogenesis, tumor immunosuppression and tumor infiltration of various cancers. Previously, we reported that a large number of infiltrated tumor promoting CD204 TAMs within esophageal squamous cell carcinomas (ESCCs) contributed to the significant association of clinicopathological malignancy and poor disease free survival. However, the relevant malignant progression mechanisms have not been studied explicitly yet. To elucidate roles of TAMs in ESCCs, we established an in vitro macrophage model using human peripheral blood acquired by healthy volunteer donors. Peripheral blood monocytes were treated with 25 ngmL recombinant human M-CSF for 6 days to induce macrophage-like differentiation (macrophage-like cells), then exposed to the conditioned media of TE series ESCC cell lines (TECM) for 2 days to induce TAM-like cells. From the cDNA microarray data between macrophages-like cells treated with and without TECM, we interested in upregulated genes. Among highly expressed genes in TAM-like cells, we focused on neural cell adhesion molecule (NCAM) which was a possibility to act on the regulation between tumor and its surrounding stroma. Gene knockdown of NCAM by siRNA in TAM-like cells revealed significant suppression of cell survival and migration via decrease of PI3KAkt signaling and downregulation of fibroblast growth factor receptor 1 (FGFR1) expression. Interestingly, fibroblast growth factor-2 (FGF-2) derived from ESCCs promotes FGF2FGFR1 autocrine loop, and activates FGFR1 signaling in TAM-like cells. Furthermore, we analyzed 70 ESCC tissue samples by immunohistochemistry whether the expression levels of FGF-2 were associated with clinicopathological background factors of ESCC patients. Relationships of the expression levels of FGF-2 in human ESCC stromal cells including macrophages had a correlation with the depth of invasion, blood vessel invasion, TNM classification UICC cancer staging and high number of infiltrating CD163 positive and CD204 positive macrophages as a marker for the M2 macrophage phenotype. These findings may indicate novel roles of FGF-2-NCAMFGFR1 interplay in ESCCs and its microenvironment including TAMs.