GRP78通过β-catenin/TCF4通路调控HOXB9影响肝癌侵袭转移的作用及机制研究

Invasion and metastasis are the key factors of impacting prognosis of hepatocellular carcinoma (HCC). Studies have revealed that dramatic reduction was in the invasion and metastasis of HCC，while the glucose regulative proteins GRP78 expression decrease, and overexpression of HOXB9 was closely related to tumor invasion and metastasis. Our previous studies found that GRP78 protein and HOXB9 protein were both overexpressed in HCC tissues，and the reduction of GRP78 protein could cause HOXB9 decreased expression in HCC cells by cDNA microarray and Western blot. Our previous studies also have found the ubiqutilation of β－catenin could be inhibited by GRP78 which impact phosphorylation of β－catenin, and the expression of HOXB9 was directly regulated byβ－catenin/TCF4 pathway. Thus, we supposed that GRP78 could affect HCC invasion and metastasis depend regulating HOXB9 byβ－catenin/TCF4 pathway. To further identify this hypothesis, we will firstly detect the protein expression of GRP78 and HOXB9 in clinical HCC samples and analyze the relationship with clinicopathological and prognosis, then to investigate the impact on the biological activity of GRP78 regulating HOXB9 on HCC invasion and metastasis in vivo and vitro. Finally, we will explore the molecular biology mechanism of GRP78 regulating HOXB9 byβ－catenin/TCF4 pathway. This study will supply the theoretical basis for clarifying mechanism of HCC invasion and metastasis.

侵袭转移严重影响原发性肝癌预后。研究示下调GRP78蛋白明显降低肝癌的侵袭转移；HOXB9过表达促进肿瘤侵袭转移。我们前期研究发现肝癌组织中GRP78及HOXB9蛋白均过表达；并用实验证实降低肝癌细胞中GRP78表达能下调HOXB9；同时发现GRP78可影响β－catenin磷酸化而使其不致泛素化降解；HOXB9表达受β-catenin/TCF4通路直接调控。因此我们推测GRP78通过β－catenin/TCF4通路调控HOXB9表达影响肝癌的侵袭转移，具体机制待研究。为验证这一科学假说，本课题拟先分析肝癌组织GRP78和HOXB9表达相关性，研究其与患者临床特征及预后的关联；其次用体内外实验明确GRP78调控HOXB9影响肝癌侵袭转移；最后研究GRP78如何影响β－catenin/TCF4通路从而调控HOXB9表达。本研究将阐明肝癌侵袭转移新机制，为肝癌防治提供新思路。

GRP78和HOXB9在肝癌的发生发展中起着至关重要的作用。在本研究中，我们分析了肝癌患者组织标本中GRP78和HOXB9在肝癌组织中的表达相关性及其临床意义，结果表明GRP78和HOXB9的高表达是肝癌发病的高危因素，高表达的GRP78和HOXB9的肝癌患者其术后五年生存率明显低于低表达GRP78和HOXB9的肝癌患者组。并且GRP78和HOXB9与肿瘤微卫星的形成、肿瘤大小和血管浸润密切相关。发现干扰GRP78可以在体内和体外抑制肝癌细胞的侵袭和转移能力。下调GRP78的表达降低了HOXB9的表达，抑制了细胞的侵袭和转移，而过表达HOXB9对GRP78的表达没有显著影响，反而增加了细胞的侵袭和转移。然而，当HOXB9在GRP78敲除细胞中过表达时，GRP78敲除诱导的侵袭和迁移能力下降得到了恢复。并用一系列实验验证了GRP78可以通过wnt/β-catenin信号通路调控HOXB9的表达，进而影响肝癌细胞的侵袭和转移。进一步研究发现GRP78通过LRP6调控WNT信号通路影响HOXB9的表达，从而影响肝癌细胞的侵袭和转移。我们的结果揭示了一个新的肝癌细胞侵袭和转移机制，对肝癌的分子靶向治疗提供新的依据。