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

Abstract

Objective: 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. Methods: 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 in vivo were observed and compared. Results: 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)%, P=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) %, P=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)%, P=0.013] and reduced the percentage of G(0)/G(1)-phase cells [(38.2±3.8)% vs (48.8±2.9)%, P=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 (P=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)%, P=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 (P=0.012 and P=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 (P=0.001). Conclusions: 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.

Keywords: Carcinoma, hepatocellular; Drug sensitivity; Sorafenib; YAP.