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Background/Aims : Migration of activated hepatic stellate cells (HSC) is a key event in the progression of liver fibrosis. Little is known about transmembrane proteins involved in HSC motility. Tetraspanins (TM4SF) have been implicated in cell development, differentiation, motility and tumor cell invasion. We evaluated the expression and function of four TM4SF, namely CD9, CD81, CD63 and CD151, and their involvement in HSC migration, adhesion, and proliferation. Methods/Results : All TM4SF investigated were highly expressed at the human HSC surface with different patterns of intracellular distribution. Monoclonal antibodies directed against the four TM4SF inhibited HSC migration induced by extracellular matrix proteins in both wound healing and haptotaxis assays. This inhibition was independent of the ECM substrates employed (collagen type I or IV, laminin), and was comparable to that obtained by incubating the cells with an anti-β1 blocking mAb. Importantly, cell adhesion was unaffected by the incubation with the same antibodies. Co-immunoprecipitation studies revealed different patterns of association between the four TM4SF studied and β1 integrin. Finally, anti-TM4SF antibodies did not affect HSC growth. Conclusions : These findings provide the first characterization of tetraspanins expression and of their role in HSC migration, a key event in liver tissue wound healing and fibrogenesis.

1044 LYSOPHOSPHATIDIC ACID RECEPTOR 6 (LPA6) PROMOTES HEPATOCELLULAR CARCINOMA GROWTH AND PROGRESSION THROUGH ACTIVATION OF PIM-3 PROTO-ONCOGENE KINASE A. Mazzocca, F. Dituri, F. De Santis, L. Lupo, A. Azzariti, C. Sabba, G. Giannelli. Internal Medicine Unit C. ‘Frugoni’ University of Bari A. Moro, Section of General Surgery and Organ Transplantation, University of Bari Medical School, Department of Experimental Oncology, National Cancer Institute, Bari, Italy E-mail: gianluigi.giannelli@uniba.it

276 LYSOPHOSPHATIDIC ACID RECEPTOR 6 (LPA6) IS A MASTER REGULATOR ORCHESTRATING AND PROMOTING TUMOR GROWTH DURING HCC PROGRESSION A. Mazzocca, F. Dituri, F. De Santis, S. Antonaci, G. Giannelli. Department of Emergency and Organ Transplantation, Section of Internal Medicine Allergology and Immunology, Internal Medicine, Immunology and Infectious Diseases, Section of Internal Medicine, University of Bari, Bari, Italy E-mail: g.giannelli@intmed.uniba.it

276 LYSOPHOSPHATIDIC ACID RECEPTOR 6 (LPA6) IS A MASTER REGULATOR ORCHESTRATING AND PROMOTING TUMOR GROWTH DURING HCC PROGRESSION A. Mazzocca, F. Dituri, F. De Santis, S. Antonaci, G. Giannelli. Department of Emergency and Organ Transplantation, Section of Internal Medicine Allergology and Immunology, Internal Medicine, Immunology and Infectious Diseases, Section of Internal Medicine, University of Bari, Bari, Italy E-mail: g.giannelli@intmed.uniba.it

Aim of the study: The purpose of the present work was to examine the intracellular pathway activated by SDF-1 in HuCCt cells and whether SDF-1 could act as a growth factor and/or a survival factor for HuCCt cells. Materials and Methods: HuCCt cells and primary hHSC were employed. Intracellular signaling and apoptotic pathways were investigated by Western blot analysis. Differences in the activation of different signaling proteins compared to control conditions were detected by densitometric analysis. Growth of HuCCt cells was investigated by cell count. Results: Following stimulation of HuCCt with SDF-1, the phosphorylation of Akt, Erk and JUN increased compared to control after 5 minutes and decreased at later time points. Phosphorylation of Akt and Erk was inhibited by AMD3100, a specific inhibitor of CXCR4. HSC conditioned medium (CM) induced a 30% increase of HuCCt growth compared to control, whereas stimulation with SDF-1 was without any effect. The antiapoptotic effect of SDF-1 was evaluated by measurement of cleaved-PARP and expression of BclXl in presence of an apoptotic stimulus, i.e. Arsenic trioxide (AT). AT induced apoptosis was inhibited by the coincubation of SDF-1. Conclusions: SDF-1, secreted by HSC, induces Erk, Akt and JUN phosphorylation at different time points and this coincides with a modest survival effect on HuCCt cells.