Hepatocellular carcinoma (HCC) is usually a highly prevalent cancer with poor prognosis. and metastasis were obtained through in vivo analyses. PCR array results revealed upregulation of SNAI1 in FABP5\overexpressing HepG2 cells. Western blot analysis showed significantly increased manifestation of At the\cadherin and ZO\1 and decreased SNAI1 manifestation and nuclear translocation of \catenin by knockdown of FABP5. We revealed a significant role for FABP5 in HCC progression and DZNep metastasis through the induction of epithelial\to\mesenchymal transition. FABP5 may be a potential novel prognostic biomarker and new therapeutic target for HCC. Keywords: Epithelial\mesenchymal transition, fatty acid\binding protein, hepatocellular carcinoma, metastasis, prognosis Introduction Hepatocellular carcinoma (HCC) is usually a highly prevalent malignancy and the third cause of malignancy\related death worldwide 1. Surgical treatments such as liver resection and transplantation are the best curative local treatments for HCC 2. However, the rate of recurrence and metastasis are still high even after curative hepatectomy 3. The rate of recurrence of HCC in patients who underwent curative surgical or regional therapy is usually 75% at DZNep the fifth 12 months 4, and the rate DZNep of recurrence is usually 86.5% for intrahepatic metastasis and 13.5% for extrahepatic metastasis 5. At present, serum biomarkers, such as alpha\fetoprotein (AFP) and prothrombin induced by vitamin K absence II (PIVKA II), and many clinicopathological factors are used for prognostic markers of HCC 6, 7, but they are not adequate DZNep to forecast survival or recurrence after curative hepatectomy 8. Hence, new biomarkers that are effective for predicting prognosis, recurrence, and metastasis in HCC are highly needed. In a previous study, we recognized fatty acid\binding protein 5 (FABP5) as a protein that was highly expressed in human HCC tissues and cell lines compared with normal liver tissues and hepatocytes 9, 10. CD209 FABP5, also known as psoriasis\associated fatty acid\binding protein, epidermal, or cutaneous fatty acid\binding protein (PA\, At the\, or C\FABP), is usually an isoform of the FABPs, which are small (~15?kDa) soluble intracellular lipid\binding proteins that hole a variety DZNep of retinoids and long\chain fatty acids 11, 12, 13. FABPs transport lipids to cellular storage compartments for the storage of lipid droplets, trafficking and membrane synthesis, and transcriptional rules 14. FABP5 functions to enhance the transcriptional activity of the nuclear receptor peroxisome proliferator\activated receptor /; promotes cell migration, proliferation, and survival; and also exhibits pro\oncogenic activities 15, 16, 17. FABP5 is usually overexpressed in many human cancers including prostate 18, 19, esophageal 20, squamous cell carcinoma 21 and breast malignancy 22, 23. However, no reports have examined the clinicopathological significance and underlying molecular mechanisms of FABP5 in HCC. In this study, we evaluated the correlation between the manifestation of FABP5 and malignant behavior of HCC in human HCC tissues and HCC cell lines. Materials and Methods Patients and specimens Human liver tissues were obtained from 243 patients who underwent surgical resection of main HCC between 1997 and 2006 at the Department of Gastroenterological Surgery I, Hokkaido University or college Hospital. Clinical characteristics of the patients are summarized in Table?1. This study was approved by the Institutional Review Table of the Hokkaido University or college, School of Advanced Medicine. Informed consent was obtained from each individual in accordance with the Ethics Committees Guidelines for our institution. Table 1 Clinical characteristics of 243 HCC patients Immunohistochemical study Formalin\fixed and paraffin\embedded specimens were cut by microtome and mounted on photo slides. Deparaffinization and antigen retrieval were performed, using PT Link and EnVision FLEX Target Retrieval.