ZBP-89抑制缺氧信号通路对肝癌干细胞的影响

Our previous studies have demonstrated that the over-expression of transcription factor ZBP-89 leads to the significant reduction of liver cancer stem cell (LCSC) markers (EpCAM, CD13), and HIF-1α, HIF-2α in hepatocellular carcinoma (HCC) cells. ZBP-89 can also significantly reduce the proliferation of HCC cells and increase the sensitivity of HCC cells to chemotherapy. The expression of ZBP-89 in HCC tissues was negatively correlated with the levels of EpCAM, CD13, and the high expression of ZBP-89 was an indicator for better prognosis for HCC. Therefore, we speculate that ZBP-89 may be a potential tumor suppressor in the development of HCC. It is very likely that the suppression of hypoxic signaling pathway by ZBP-89 is critical for ZBP-89-mediated inhibition of LCSC proliferation and enhancement of chemosensitivity. Based on our previous work, this study aims to further explore the mechanism how ZBP-89 inhibits hypoxia signaling pathway, leading to the suppression of LCSC stemness and the enhancement of pharmacotherapy. The study will be carried out in vitro cell culture and in vivo mouse models to uncover the relationship between ZBP-89 and HIF-1α, as well as HIF-2α signaling pathway, to investigate the mechanism responsible for the inhibitory effect of ZBP-89 on the hypoxic signaling pathway and LCSC stemness. We hope that the result of this study will generate some novel molecular data for us to understand the liver carcinogenesis and to improve the current treatment for HCC.

我们的前期研究显示：肝癌细胞中转录因子ZBP-89过表达导致肝癌干细胞标记物（EpCAM、CD13）和HIF-1α、HIF-2α的表达明显减低，肝癌细胞增殖抑制和化疗敏感性增强；肝癌组织中ZBP-89的表达与EpCAM、CD13的表达呈负相关，ZBP-89高表达的患者预后较好。因此，我们推测其可能是肝癌发展过程中一潜在的抑癌基因。通过抑制缺氧信号通路进而抑制肝癌干细胞增殖和增强细胞化疗敏感性可能是其发挥抑癌效应的重要机制。基于前期的工作基础，本项目拟通过体外实验和体内研究进一步探讨ZBP-89抑制缺氧信号通路的机制和对肝癌干细胞干性特征的影响。体外肝癌干细胞中研究其抑制缺氧信号通路的机制及对肝癌干细胞的影响；体内肝癌裸鼠模型中进一步加以验证。该研究有利于进一步揭示肝癌发病的分子机制，为肝癌治疗提供新的思路。

我们的前期研究提示ZBP-89可能是肝癌发展过程中一潜在的抑癌基因，其抑癌作用可能通过影响缺氧因子来完成，而缺氧信号通路与肝癌干细胞生长和增殖关系密切。本研究拟通过临床标本、体外机制研究和动物模型验证三个层次进一步探讨ZBP-89抑制缺氧信号通路的机制和对肝癌干细胞的影响。本课题证实了ZBP-89可抑制肝癌的生长，其降低癌细胞生长的作用是通过多个途径抑制LCSC而实现的，不但可影响缺氧因子，也可下调肝癌干细胞的标志物及其相关分子，包括EpCAM，CD44，CD13，Sox2, c-myc, histone deacetylase 3 (HDAC3), 和 Notch1。本课提研究亦发现ZBP-89的水平与肝癌干细胞的标志物的表达和肿瘤的复发呈负相关。同时，研究结果显示ZBP-89可以明显地增强肝癌细胞对索拉非尼的敏感性。总而言之，本研究试验的证据支持ZBP-89是一肝癌的抑制物，其抑制作用可能主要通过多途径下调肝癌干细胞来实现。本课提研究结果将有助于开发抑制肝癌生长的新药物／方法。