2A; Supporting Fig. 1F). Twenty-three of twenty-seven cases of HCCs (85%) showed a decreased Rnd3 expression, when compared to peritumor tissue. Mean tumor/nontumor ratio Dinaciclib mw was 0.68 ± 0.08 (P = 0.0005). Using IHC, Rnd3 expression in peritumor tissue varied from faint to intense and was predominantly localized to the cytoplasm of hepatocytes (Fig. 2B). In contrast, low or no expression was observed in tumor samples (Fig. 2B). Rnd3 protein expression was also determined in healthy primary human hepatocytes as well as in the tumor cell lines, Huh6, Huh7, SNU398, SNU475, Hep3B,

and HepG2. Results showed that Rnd3 expression was reduced in all tumor cell lines tested, as compared to primary hepatocytes (Fig. 2C). Because RND3 expression showed a strong correlation with the presence of satellite nodules in HCC, we analyzed the effect of changes in RND3 expression level on cell invasion in the

Hep3B HCC cell line. Lentiviral transduction led to a 6-fold overexpression of Rnd3, which was associated with a 4.5-fold reduction in cell ability to invade Matrigel (Fig. 3A). On the other hand, transient Rnd3 knockdown using two different siRNAs led to decreased expression of Rnd3 protein by 95% (S1) or 75% (S3) (Fig. 3B) and resulted in a significant increase in invasion (Fig. 3B). The increase was more drastic with S1 than S3, which is in agreement with their silencing efficacy. While performing invasion assays, we also analyzed cell growth and found that Rnd3 knockdown led to an inhibition of HCC cell growth (Fig. 3C). Thus, our results demonstrate that Rnd3 expression levels Ku-0059436 in vivo inversely regulate HCC cell-invasion and growth properties. Because of our initial observation that down-regulation of Rnd3 was associated with evidence of an invasive phenotype in patients, and to better characterize Rnd3 involvement in HCC progression, we focused our study on the invasion mechanism. Because loss of the cell-junction protein, E-cadherin, is associated cAMP with HCC cell invasiveness,23, 24 we evaluated E-cadherin

expression in Rnd3-depleted cells. Rnd3 silencing in Hep3B (Fig. 4A,B) using both siRNAs led to a significant decrease in E-cadherin mRNA expression, whereas a significant down-regulation of E-cadherin protein was only observed with S1. However, decrease of E-cadherin protein expression was significantly observed with both siRNAs in Huh7 cells (Supporting Fig. 2A). IF analyses confirmed that E-cadherin expression was strongly reduced at cell-cell contacts in Rnd3-silenced cells (Supporting Fig. 2B). These results suggest that Rnd3 depletion affected the integrity of adherens junctions. We then sought to analyze E-cadherin protein levels in the 27 HCCs previously used for measuring Rnd3 expression. E-cadherin expression was down-regulated in 16 of 27 HCCs, as compared to peritumor tissue (Supporting Fig. 3).