Several pieces of evidence in this study support a close association

between FoxC1 expression and HCC metastasis. First, FoxC1 protein and mRNA levels were correlated with the metastatic potential of the HCC cell lines examined. Second, FoxC1 expression was markedly higher in metastatic lesions, compared with their corresponding primary tumor samples. Third, up-regulation of FoxC1 significantly promoted the invasion and lung metastasis of HCC cells, whereas the knockdown of FoxC1 decreased the invasion and metastasis of HCC cells. EMT plays an important role in HCC invasiveness and metastasis.34, 35 The EMT transition triggered during tumor progression is controlled by several transcription factors, including Twist, Snai1, Slug, Goosecoid, ZEB1, and SIP1.24 In this study, we found that the overexpression of FoxC1 had a significant effect on EMT, as indicated

by the increased Selleckchem Sirolimus expression of mesenchymal markers (fibronectin and vimentin) and decreased expression of epithelial markers (E-cadherin and ß-catenin). In contrast, knockdown of FoxC1 decreased the expression of mesenchymal markers and increased the expression of epithelial markers. EMT is a key event in tumor invasion and metastasis; epithelial cells lose their epithelial adherence and cell-cell contacts and undergo remarkable cytoskeletal remodeling to facilitate cell motility and invasion.36 Thus, HCC cells overexpressing FoxC1 find more most likely become more invasive by undergoing EMT. Disruption of the E-cadherin-mediated adhesion system is a major event in the transition from a noninvasive

tumor to invasive malignant carcinoma and is a key biomarker for EMT.23 E-cadherin is directly repressed by Snai1, which, in turn, induces mesenchymal phenotype acquisition in epithelial tumor cells.37, 38 FoxC1 increases cell migration and invasion in mammary epithelial cells by inhibiting E-cadherin expression.18 However, the molecular mechanism by which FoxC1 inhibits E-cadherin expression remains unknown. This study was the first to demonstrate that FoxC1 transactivates Snai1 expression by directly binding to its promoter, thus leading to the inhibition of E-cadherin transcription by its repressor, Snai1. Inhibition of Snai1 expression significantly suppressed FoxC1-enhanced invasion and lung metastasis. In addition, in a cohort of 406 medchemexpress human HCC tissues, we found that FoxC1 expression was positively correlated with Snai1 expression, but inversely correlated with E-cadherin expression. More important, patients exhibiting FoxC1(+)/Snai1(+) coexpression had the highest recurrence rates and lowest OS among the four subgroups, whereas patients exhibiting FoxC1(+)/E-cadherin(−) expression had shorter OS times and higher recurrence rates. Thus, both experimental and clinical evidence indicate that the FoxC1/Snai1/E-cadherin pathway may play an important role in promoting HCC metastasis and producing a poor clinical outcome.