Recent studies have reported that CtBP2 is recruited to the E-cadherin promoter and modulates its transcription [29]. The Levine group demonstrated that the CtBP2 interaction motif P-DLS-K is present in the repression domains of SNAI1 [30]. Due to the increased SNAI1 expression we found in our previous study [21] and the enhanced CtBP2 expression observed in Huh7 GLI1 cells in this study, we conducted a Co-IP assay to observe whether CtBP2 and SNAI1 directly interact. We found that the CtBP2 protein bound the SNAI1 protein in the nucleus of Huh7 GLI1 cells (Figure 6C). To investigate the role of CtBP2 in GLI1/SNAI1 driven EMT, we used expression in Huh7 GLI1 cells (Figure 6D). We found that E-cadherin expression was increased in the siRNA CtBP2 silenced cells, that the expression of N-cadherin, Vimentin and Fibronectin were repressed, and that SNAI1 expression was not significantly altered (Figure 6E). On the other hand, CtBP2 knockdown in Huh7 Vector cells did not affect the expression of aforementioned EMT markers clearly. These data indicated that CtBP2 bound SNAI1 as a transcriptional co-repressor and, thereby, promoted GLI1/SNAI1 driven EMT in HCC.
