Patients with hepatocellular carcinoma (HCC) are vulnerable to drug resistance. Although drug resistance has been taken much attention to HCC therapy, little is known of regorafenib and regorafenib resistance (RR). This study aimed to determine the drug resistance pattern and the role of RhoA in RR. Two regorafenib-resistant cell lines were constructed based on Huh7 and Hep3B cell lines. In vitro and in vivo assays were conducted to study RhoA expression, the activity of Hippo signaling pathway and cancer stem cell (CSC) traits. The data showed that RhoA was highly expressed, Hippo signaling was hypoactivated and CSC traits were more prominent in RR cells. Inhibiting RhoA could reverse RR, and the alliance of RhoA inhibition and regorafenib synergistically attenuated CSC phenotype. Furthermore, inhibiting LARG/RhoA increased Kibra/NF2 complex formation, prevented YAP from shuttling into the nucleus and repressed CD44 mRNA expression. Clinically, the high expression of RhoA correlated with poor prognosis. LARG, RhoA, YAP1 and CD44 show positive correlation with each other. Thus, inhibition of RhoGEF/RhoA has the potential to reverse RR and repress CSC phenotype in HCC.

中文翻译：

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抑制 RhoGEF/RhoA 通过 Hippo 信号通路减轻肝细胞癌中瑞格非尼耐药和癌症干性

肝细胞癌（HCC）患者很容易产生耐药性。尽管耐药性在 HCC 治疗中备受关注，但人们对瑞戈非尼和瑞戈非尼耐药性 (RR) 知之甚少。本研究旨在确定耐药模式以及 RhoA 在 RR 中的作用。基于Huh7和Hep3B细胞系构建了两种瑞戈非尼耐药细胞系。进行体外和体内测定来研究 RhoA 表达、Hippo 信号通路的活性和癌症干细胞 (CSC) 特征。数据显示，RR 细胞中 RhoA 高表达，Hippo 信号传导低活性，CSC 特征更为突出。抑制 RhoA 可以逆转 RR，并且 RhoA 抑制和瑞格非尼联合可协同减弱 CSC 表型。此外，抑制 LARG/RhoA 会增加 Kibra/NF2 复合物的形成，阻止 YAP 穿梭进入细胞核并抑制 CD44 mRNA 表达。临床上，RhoA的高表达与不良预后相关。LARG、RhoA、YAP1 和 CD44 彼此呈正相关。因此，抑制 RhoGEF/RhoA 有可能逆转 RR 并抑制 HCC 中的 CSC 表型。