[YAP regulates the proliferation and modifies the sensitivity to sorafenib in hepatocellular carcinoma cells].

To detect the expression level of YES-associated protein 1 (YAP) in hepatocellular carcinoma (HCC) cell lines and investigate its effects on the proliferation activity and the sensitivity to sorafenib in HCC cells. Western blot was used to detect the protein expression levels of YAP in SMMC-7721, SK-Hep-1, HepG-2, Huh7 and the normal liver cell line L-O2. YAP specific small interfering RNA (si-YAP) or YAP expression plasmid were transfected in SK-Hep-1 or Huh7 cells, respectively. Cell counting kit-8 (CCK-8) test was used to detect the cell proliferation activity and the cell cycle test was conducted by flow cytometry. SK-Hep-1 and SK-Hep-1 si-YAP cells were subcutaneously injected into the nude mice which were sequentially treated by intragastric administration of sorafenib, and the tumor growth were observed and compared. The expression of YAP was upregulated in HCC cell lines. Deletion of YAP expression significantly decreased the survival rate of SK-Hep-1 cells [(78.5±0.3)% vs (92.3±0.2)%, =0.025]. Knockdown of YAP significantly increased the percentage of G(0)/G(1)-phase cells [ (65.4±3.3) % vs (55.7±3.4) %, =0.039]. On the contrary, upregulation of the YAP expression in Huh7 cells significantly increased the cell survival rate [(81.2±1.3)% vs (62.5±1.1)%, =0.013] and reduced the percentage of G(0)/G(1)-phase cells [(38.2±3.8)% vs (48.8±2.9)%, =0.019]. The survival rate of SK-Hep-1 cells treated by si-YAP combined with sorafenib was (31.13±1.79)%, significantly lower than (48.87±0.58) % of SK-Hep-1 cells treated by sorafenib alone (=0.001), while overexpression of YAP attenuated the inhibitory effect of sorafenib on the survival of Huh7 cells [(69.98±2.94) % vs (53.53±1.93)%, =0.001]. The tumor weights of SK-Hep-1 group, sorafenib alone group, SK-Hep-1 si-YAP group and SK-Hep-1 si-YAP combined with sorafenib group were (0.96±0.08) g, (0.62±0.08) g, (0.70±0.06) g and (0.27±0.02) g, respectively. The tumor weights of sorafenib alone group and SK-Hep-1 si-YAP group were significantly lower than that of SK-Hep-1 group (=0.012 and =0.031, respectively). The tumor weight of SK-Hep-1 si-YAP combined with sorafenib group was significantly lower than that of SK-Hep-1 si-YAP group (=0.001). The expression of YAP is upregulated in HCC cell lines, which regulates the proliferation, cell cycle, and sensitivity to sorafenib of HCC cells. YAP is a potential molecular target for HCC treatment.