Nuclear orphan receptor COUP-TF2 induces anoikis resistance, amoeboid migration and metastatic potential in hepatocellular carcinoma (HCC)

Introduction: HCC is the second cause of cancer-related death worldwide. In the last years, the role of nuclear receptors in hepatocarcinogenesis has received great attention. COUP-TF2 regulates important biological processes and. studies indicate that is a prooncogenic factor but its role in HCC is still controversial. Aim of this study was to evaluate the role of COUP-TF2 in HCC. Materials and methods: Results COUP-TF2, evaluated by immunohistochemistry, is over-expressed in primary HCC samples and Kaplan–Meier and Cox regression analysis show that it may be an independent prognostic factor of worst outcome. Overexpression of COUP-TF2, through stable transfection with pcR3.1/COUP-TF2, has no significant effects on cell proliferation. The migration and the ability to colonize sites distant from the growth front were evaluated by Time-Laps microscopy showing that COUP-TF2 induces a pro-metastatic phenotype characterized by an increased anoikis resistance and amoeboid migration. Western blot and immunofluorescences show that proteins involved in the organization of the cytoskeleton, cell-cell or cell-substrate, were differently modulated in COUP-TF2 overexpressing vs control cells. After we studied the role of COUP-TF2 in an in vivo models of mouse carcinogenesis (TgN(Alb1HBV)44Bri) realizing a triple transgenic animal where the liver-specific Cre expression deletes COUP-TF2 in hepatocytes (Tg[HBV]CreKOCOUP-TF2). COUP-TF2 deletion reduces tumour growth. Finally, for to evaluate the role of COUP-TF2 in metastasis formation we used a xenograft model where mice were inoculated with human smmc7721 hepatocarcinoma cells stable transfected with COUP-TF2 or silenced by specific short hairpin. COUP-TF2 overexpression induces an increase, number of lung metastasis whereas its deletion reduces pulmonary metastasis compared to control animals. Conclusion: In the light of our data, COUP-TF2 appears to play a role in the metastatic progression of HCC. The evidence that COUP-TF2 transcriptional activity could be potentially regulated by ligands, indicates that this nuclear receptor is a promising therapeutic target for HCC.