核受体FXR下调LOXL2表达抑制肝细胞癌侵袭转移的作用及机制研究

High levels of LOXL2 play a critical role in invasion and metastasis of HCC. While much is known about the regulation of LOXL2. Moreover it is unclear whether the nuclear receptor FXR plays its anti-tumor role via down-regulating LOXL2. Our preliminary data showed that in HCC patient samples and HCC cell lines FXR levels were decreased while LOXL2 overexpressed, and the levels of FXR and LOXL2 were associated with the aggressive protential of HCC. Bioinformatic analysis showed that there were potential binding sites for FXR in human LOXL2 promoter region.FXR could dramatically suppressed LOXL2 expression and significantly inhibited its transcriptional activity. In the present study, we investigate the regulation of LOXL2 by FXR and the corresponding mechanism by some technologies such as reporter assy, EMSA, and ChIP. Subsequently, we will investigate the significance of FXR-mediated LOXL2 downregulation in the inhibiting invasion and metastasis in hepatocytes in vitro and in HCC mice models in vivo.So that we hope to reveal that FXR-LOXL2 pathway is a novel mechansim of FXR-mediated anti-HCC.Furthermore,our study may provide a new sight for searching novel strategy to the inhibition invasion and metastasis of HCC by targeting FXR -LOXL2 pathway.

LOXL2在肝细胞癌（HCC）中表达异常增高，促进肿瘤侵袭转移。因此抑制LOXL2的过表达有助于HCC的治疗。然而目前关于LOXL2自身的表达调控机制尚不清楚。我们前期研究发现抑癌核受体FXR与LOXL2在HCC中的表达水平呈负相关，生物信息学分析提示LOXL2启动子区具有潜在的FXR结合位点，FXR活化后可显著下调LOXL2的mRNA和蛋白表达，并抑制其转录活性。因此我们推测：LOXL2是FXR的又一新靶基因，FXR可能从转录水平下调LOXL2表达，发挥抗HCC侵袭转移的功能。为此，我们拟借助报告基因检测、EMSA、ChIP等技术阐明FXR调控LOXL2的分子机制，阐明FXR下调LOXL2表达的具体分子机制，并通过HCC细胞株和肝癌移植动物模型，从离体和在体揭示FXR下调LOXL2表达在抑制HCC侵袭转移中的作用，为探索以FXR-LOXL2为靶标的HCC治疗提供新的实验依据和理论基础。

赖氨酰氧化酶样蛋白2（LOXL2）在肝细胞癌（HCC）中表达异常增高，促进肿瘤侵袭转移。抑制LOXL2的过表达有助于HCC的治疗。然而目前关于LOXL2自身的表达调控机制尚不清楚。法尼醇X 受体（FXR）为核受体超家族的重要成员，除密切参与调节物质代谢外，还具有重要的抗肿瘤功能，但具体的机制有待进一步阐明。在本课题研究中，我们明确了FXR、LOXL2在HCC肿瘤组织中和HCC细胞株中的表达呈显著负相关性，并且二者表达水平与HCC的迁移侵袭有关。生物信息学分析提示LOXL2启动子区具有潜在的FXR结合位点，FXR活化后可显著下调LOXL2表达，并抑制其转录活性。并进一步通过回复实验揭示了FXR下调LOXL2的表达在抑制HCC侵袭转移中的作用。以上实验结果不仅可能丰富LOXL2在HCC侵袭转移中的自身表达调控机制，更重要的是可能为将来基于FXR-LOXL2为靶标的HCC临床治疗提供理论及实验依据。