LIMK-1协同ERK入核活化EGFR信号通路促进肝癌转移的机制研究

Lim Kinase I (LIMK-1) was confirmed as a metastasis-promoting factor of hepatocellular carcinoma (HCC) from a cDNA microarray data with lymphatic metastasis. Clinical data indicates that the nuclear translocation of LIMK-1 is highly related with HCC metastasis. We have confirmed the direct interaction between LIMK-1 and ERK. EGF could dramatically stimulate the nuclear translocation of LIMK-1. We proposed that LIMK-1 and ERK interacts synergistically to active EGFR signaling and stimulate HCC metastasis. HDAC could interact directly with LIMK-1 to mediate the EGFR signaling pathway mediated HCC metastasis. In this study, we will investigate the vital role of nuclear LIMK-1 in promoting HCC cell proliferation, migration and metastasis both in vitro and in vivo using molecular and cell biological techniques. We will also identify the mechanism of HCC metastasis induced by the nuclear translocation of LIMK-1, as well as its activation of EGFR signaling pathway. Finally, we will evaluate the clinical significance of LIMK-1 nuclear translocation based on clinical data and pathological parameters. Our results will certainly improve our understanding on LIMK-1 induced HCC progression and also provide evidence to the development of LIMK-1 as a new therapeutic target.

LIM激酶1（LIMK-1）是我们通过表达谱芯片筛选出来的与肝癌转移相关的蛋白，目前尚未有该蛋白在肝癌中的研究报道。前期临床结果显示，LIMK-1的核定位与肝癌的转移密切相关，但其入核促肿瘤转移的作用机制尚不清楚。信号分子ERK与LIMK-1存在相互作用，EGF可诱导LIMK-1入核。由此，我们提出LIMK-1可以协同ERK入核活化EGFR信号通路促进肝癌转移。组蛋白去乙酰化酶（HDAC）与LIMK-1存在相互作用，可能是LIMK-1发挥核内功能的重要分子。本课题拟采用分子与细胞生物学技术结合体内外功能实验，研究LIMK-1的核定位对肝癌细胞增殖、迁移及转移的影响；明确LIMK-1协同ERK入核，活化EGFR信号通路促肝癌转移的作用机制；结合临床数据与病理参数明确LIMK-1核定位的临床意义。本项目的顺利完成，为确立LIMK-1作为肝癌转移患者治疗的新靶点提供更为充分的科学依据。

LIM激酶1（LIMK1）是一种丝氨酸/苏氨酸和酪氨酸激酶，主要定位于细胞质中。本研究发现，LIMK1在肝癌组织中高表达，并且LIMK1的核内表达与肝癌患者预后不良呈正相关。目前，细胞质中LIMK1在丝切蛋白磷酸化和肌动蛋白丝动力学的重要作用已被广泛认识，但细胞核中LIMK1的功能仍有待研究。肝癌细胞系体内外研究证实LIMK1的核内过表达促进肝细胞癌的恶性进展。表皮生长因子（EGF）能激活p-ERK和LIMK1的相互作用并促进LIMK1核定位。此外，研究还证实了LIMK1可以靶向作用于c-Myc的启动子，转录激活c-Myc，进而促进肝细胞癌进展。尽管临床上靶向表皮生长因子受体（EGFR）的药物西妥昔单抗对HCC患者治疗欠佳，但在本研究中，西妥昔单抗对LIMK1核内过表达肝细胞癌进展抑制作用显著。以上研究结果为LIMK1核内表达的肝细胞癌患者提供了新的西妥昔单抗治疗策略。