894 ALPHA-FETOPROTEIN CAN BE USED AS A PANCREATIC CANCER STEM CELL MARKER

POSTERS single, 28 multiple tumors). Serial samples at pre-TACE, the 3rd , and the 7th day after TACE were obtained to analyze the changes of plasma VEGF levels using an enzyme-linked immunosorbent assay (ELISA) in all patients. CT was done to evaluate recurrence of HCC at 1 month after TACE in all patients and at 3 months thereafter in 70% of patients. Results: The levels of plasma VEGF were increased transiently at the 3rd day after TACE and declined thereafter in 16 patients (34%). Serial continuous increase or decrease of VEGF levels at the 3rd and the 7th day after TACE compared with those of pre-TACE were noted in 15 (31.9%) and 10 (21.3%), respectively. 6 (12.8%) showed increase of VEGF level at the 7th day after transient decrease at the 3rd day after TACE. Serial continuous decrease of VEGF levels at the 3rd and the 7th was frequently found in patients with tumor size <3 cm (P = 0.01) and single tumor (P = 0.04). 10 patients with serial decrease of VEGF levels did not show no viable tumor or new HCC lesion on 1 month follow-up CT, compared with much more frequent recurrence in patients with the other change pattern of VEGF levels (P = 0.02). There was no relationship between 1 month recurrence of HCC after TACE and age, gender, Child–Pugh class, portal vein thrombosis, tumor numbers, causes of HCC, and baseline AFP or VEGF levels. Conclusions: The serial continuous decrease of plasma VEGF levels at the 3rd and the 7th day after TACE may predict effectiveness of TACE procedure. 894 ALPHA-FETOPROTEIN CAN BE USED AS A PANCREATIC CANCER STEM CELL MARKER N. Sasaki, T. Ishii, K. Yasuchika, R. Kamimura, R. Doi, S. Uemoto. Department of Surgery, Graduate School of Medecine, Kyoto University, Kyoto, Japan E-mail: [email protected] Background: Many evidences for the existence of cancer stem cells (CSCs) have been reported in various malignancies including leukemia, brain tumor and breast cancer. CSCs are supposed to have some similarities to normal tissue stem cells. In this study, we focused on alpha-fetoprotein (AFP) as a pancreatic CSC marker which is commonly used as a tumor marker of liver malignancies. It is because AFP is one of the most common markers for anterior foregut endoderm, from which both liver and ventral pancreatic anlagen arise. We aimed to demonstrate that AFP can be used as a pancreatic cancer stem cell marker. Methods: We used six human pancreatic cancer cell lines (AsPC-1, KP-1NL, MIAPaCa-2, PANC-1, QGP-1, and SUIT-2), and transfected a transgene vector that expressed enhanced green fluorescent protein (EGFP) under the control of human AFP enhancer/promoter. The proper gene insertions were confirmed by PCR. EGFP-positive and EGFP-negative cells were sorted by flowcytometry. To investigate whether the AFP-EGFP-positive cells possessed CSC-like characteristics including a self-renewal ability and multipotency, these cells were analyzed by single cell culture assays. Carcinogenesis was examined by cell proliferation assays and anchorage-independent growth assays, and by xenotransplantation to non-obese diabetic and severe combined immunodeficient (NOD/SCID) mice in vivo. Additionally, surgical specimens from 25 patients with pancreatic cancer were examined by immunohistology for AFP expression. Results: RT-PCR and immunocytohistology revealed that two of the six cell lines (AsPC-1 and PANC-1) expressed AFP. Single cell sort and culture assays showed that one EGFP-AFP-positive cell generated both the EGFP-AFP-positive and EGFP-AFP-negative fraction, whereas one EGFP-AFP-negative cell generated only the EGFP-AFP-negative cell population, suggesting the EGFP-AFPpositive cells to have the self-renewal ability and multipotency. Immunohistological assays revealed that a minority of tumor cells expressed AFP in 16 of the 25 patients with pancreatic cancer. S348

Conclusion: The AFP-producing cells in the human pancreatic cancer cell lines showed both the self-renewal and differentiation ability, and a higher proliferative activity and anchorage independency in vitro. The AFP-producing cells were also found in some patients with pancreatic cancer. These findings suggested that AFP can be a strong tool to detect pancreatic cancer stem cells. 895 A PRO- AND ANTI-ONCOGENIC ROLE OF STAT3 IN HEPATOCELLULAR CARCINOMA PROGRESSION D. Schneller1 , G. Machat1 , F. Van Zijl1 , G. Zulehner1 , V. Proell1 , H. Huber1 , M. Mair2 , S. Nijman3 , R. Eferl2 , R. Moriggl2 , W. Mikulits1 . 1 Department of Medicine I, Institut of Cancer Research/Medical University of Vienna, 2 The Ludwig Boltzmann Institute for Cancer Research, 3 Research Center of Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria E-mail: [email protected] Background and Aims: Signal transducer and activator of transcription (Stat)3 is constitutively activated in a variety of human malignancies including hepatocellular carcinoma (HCC). Neoplastic hepatocytes frequently increase malignancy by undergoing an epithelial to mesenchymal transition (EMT) during HCC progression. Yet, the role of Stat3 during EMT and advanced stages of HCC is poorly understood. Methods: We investigated the role of Stat3 in HCC progression employing loss- and gain-of-function studies in Ras-transformed murine hepatocytes with a defined genetic background. Hep3B cells were used to bridge our mouse HCC models to human hepatocarcinogenesis. Results: In this study we show that constitutive active (ca) Stat3 acts tumor-suppressive in p19ARF−/− hepatocytes in cooperation with Ras, whereas expression of dominant negative (dn) Stat3 enhances tumor formation and metastatic colonization. In accordance with these data, Ras-transformed p19ARF−/− /Stat3Dhc hepatocytes (p19ARF /Stat3 double null) show stronger proliferation kinetics after treatment with TGF-b and increased tumor formation. These observations suggest a tumor-suppressive role of Stat3. However, gain-of-function studies in Ras-transformed hepatocytes expressing p19ARF exhibited a tumor-promoting role of Stat3 in tumor formation. To test the hypothesis that Stat3 and p14ARF are molecularly connected in human HCC progression, we employed human Hep3B cells which show Stat3 activation as well as p14ARF expression. Stable knock-down of p14ARF in Hep3B hepatocytes decreased tumor formation in vivo and associated with reduced pStat3. Conclusions: From these data we conclude that p19ARF /p14ARF is essentially involved in the decision whether Stat3 executes a proor an anti-oncogenic function during HCC progression. 896 HEPACAM, A NEW IG-LIKE CELL ADHESION MOLECULE INDENTIFIED IN THE LIVER S. Shen. Physiology, National University of Singapore, Medical Drive, Singapore E-mail: [email protected] We have identified and characterized a novel gene hepaCAM in the liver. The gene is frequently silenced in hepatocellular carcinoma as well as in a diverse number of human malignancies. hepaCAM maps to chromosome 11q24 and encodes a cell adhesion molecule of the immunoglobulin superfamily, structurally displaying an extracellular segment with two Ig-like domains, a transmembrane region and a cytoplasmic tail. Biochemical analyses reveal that hepaCAM is an N-linked glycoprotein phosphorylated in the cytoplasmic domain, and forms homodimer through cis-interaction on cell surface. The subcellular localization of hepaCAM appears

Journal of Hepatology 2010 vol. 52 | S319–S457