FOXP3 is known as a master control of regulatory T cells with recently studies indicating its expression in several tumor cells. In order to study the precise role of FOXP3 in cholangiocarcinoma, FOXP3 was knocked down in cholangiocarcinoma cell lines. Down regulation of FOXP3 inhibits tumor cell invasion by reducing the quantity of MMP-9 and MMP-2. With FOXP3 knocking down, IL-10 and TGF-beta 1 secreted by cancer cells diminishes and the cell survival of T cells is significant up-regulation. These results suggest that FOXP3 plays an important role in tumor malignant phenotype, especially the invasion and immune escape. (C) 2015 Elsevier Inc. All rights reserved.