492 TUMOR ASSOCIATED MACROPHAGE PROMOTES EPITHELIAL-TO-MESENCHYMAL TRANSITION IN ESOPHAGEAL SQUAMOUS CELL CANCER

Abstract

Abstract We aimed to investigate the role of tumor associated macrophage (TAM) in epithelial-to-mesenchymal transition (EMT) in esophageal squamous cell cancer (ESCC). Methods Expression of CD68 and EMT markers was determined in resected ESCC tumors by immunohistochemistry with clinicopathologic correlation. M2-polarized macrophages were generated from human U937 cells treated with 50 ng/ml phorbol myristate acetate (PMA) while cultured with PMA plus Th2 cytokines. KYSE-510 ESCC cell was co-cultured with M2 macrophages, followed by determination of expression for EMT markers by Western blot. In situ expression of E-cadherin and vimentin was determined using immunofluorescence staining Cell proliferation, invasion and extracellular matrix (ECM) adhesion assays were performed to determine phenotypic characteristics of cultured ESCC cells. Results High expression of CD68 in resected ESCC correlated with worse survival. In addition, expression of CD68 in resected ESCC tumors correlated positively with expression of Snail and vimentin but inversely with E-cadherin. Compared with KYSE-510 cells cultured alone, those co-cultured with M2 macrophage showed higher expression of snail, vimentin, and fibronectin with a more spindle-shaped morphology, suggesting a mesenchymal differentiation. Further, cell proliferation, invasion and ECM adhesion were significantly more pronounced in M2 macrophage co-cultured ESCC cells. Conclusion EMT markers correlated with the number of TAM within resected ESCC tumors, suggesting an association of cancer inflammation in promoting EMT in ESCC. A link between cancer inflammation mediated by TAM deemed to be supported by increased expression of EMT markers and phenotypic changes related to EMT in ESCC cells co-cultured with M2 macrophage. Our results suggest an important role of TAM in promoting EMT in tumor microenvironment with regards to cancer inflammation in ESCC.