Under-expression of LKB 1 is associated with enhanced p 38-MAPK signaling in human hepatocellular carcinoma
Under-expression of LKB 1 is associated with enhanced p 38-MAPK signaling in human hepatocellular carcinoma
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发表时间：
2018
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通讯作者：
L. Sha;F. Lian;Kezhi Li;Chuang Chen;Yin-Nong Zhao;Jianbo He;Shan Huang;Guobin Wu
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作者：
L. Sha;F. Lian;Kezhi Li;Chuang Chen;Yin-Nong Zhao;Jianbo He;Shan Huang;Guobin Wu
肿瘤抑制因子肝激酶B1(LKB1)是一种高度保守且广泛表达的蛋白激酶，在肿瘤的发生发展中起着重要作用。LKB1最近被发现与几种癌症的发生有关，包括肺癌、乳腺癌和胰腺癌。然而，LKB1在肝细胞癌中的作用尚不清楚。在此，我们通过实时定量聚合酶链式反应(qRT-PCR)和免疫印迹分析检测了LKB1在肝癌患者和肝癌细胞系中的表达水平。此外，应用免疫组织化学方法(IHC)分析LKB1蛋白在石蜡包埋的肝细胞癌组织中的表达，并对其与总生存期的关系进行统计学分析。体外实验，包括RNAi研究，进一步探讨LKB1在肝癌细胞系肿瘤进展中的作用。结果表明，LKB1在肝细胞癌组织和细胞系中的表达低于相应的癌旁正常组织和正常肝细胞系(HL7702)。此外，LKB1低表达的肝细胞癌患者的临床分期比LKB1高表达的患者更早，预后更差。此外，siRNA介导的LKB1基因敲除导致肝癌细胞的增殖、迁移和侵袭能力增强。此外，LKB1的表达水平与E-钙粘蛋白水平呈正相关，其中siRNA转基因细胞的E-钙粘蛋白水平显著降低，而磷酸化的p38和波形蛋白水平升高。抑制p38MAPK信号通路可逆转E-钙粘蛋白上调和波形蛋白下调。总之，我们的结果表明，LKB1作为一个肿瘤抑制基因，可能通过参与肝癌进展的p38 MAPK信号通路来抑制EMT。
The tumor suppressor liver kinase B1 (LKB1), a highly conserved and ubiquitously expressed protein kinase, plays a critical role in tumorigenesis. LKB1 has recently been identified in tumorigenesis of several cancers including lung cancer, breast cancer, and pancreatic cancer. However, the role of LKB1 in hepatocellular carcinoma (HCC) remains unclear. Herein, we examined the expression levels of LKB1 in HCC patients and cell lines by quantitative real-time PCR (qRT-PCR) and western blot analysis. Furthermore, LKB1 protein expression was analyzed in archived paraffin-embedded HCC tissues using immunohistochemistry (IHC), and its association with overall survival was shown in statistical analysis. In vitro assays, including RNAi studies, were performed to further explore the role of LKB1 in tumor progression in HCC cell lines. Our results revealed that the expression of LKB1 was lower in HCC tissue and cell lines than in corresponding adjacent normal tissue and normal human liver cell line (HL7702). Moreover, HCC patients with low LKB1 expression had advanced clinical stage and worse prognosis than those with higher LKB1 expression. Furthermore, siRNA-mediated knockdown of LKB1 resulted in enhanced cell proliferation, migration, and invasion of HCC cells. Additionally, the expression level of LKB1 positively correlated with E-cadherin levels, wherein siRNA-transfected cells exhibited significantly decreased levels of E-cadherin, while phosphorylated p38 and vimentin levels were enhanced. Inhibition of p38 MAPK signaling was capable of reversing E-cadherin upregulation and vimentin down-regulation. In all, our results indicate that LKB1 acts as a tumor suppressor gene, which may inhibit EMT through the p38 MAPK signaling pathway involved in HCC progression.