Sulfatase2通过Hedgehog/GLI1通路调控肝细胞癌肿瘤微环境的分子机制研究

Our preliminary data showed that both Sulfatase2 and GLI1 were overexpressed in hepatocellular carcinoma (HCC) and promoted tumor recurrence and metastasis after radical resection. However, the underlying mechanism remains unclear. This project seeks to verify the following hypothesis via a research strategy including immunoprecipitation, gene silencing, spheroid 3D cell culture and transgenic mouse. In the tumor mircoenvironment of HCC, Sulfatase2 upregulates GLI1 expression by 2 distinct pathway, the first one is that more Shh is released by Sulfatase2 from the matrix of cell membrance, binded with Patchened and activate Hedgehog signaling; the second one is that Sulfatase2 increases GLI1 expression via activating TGFβ1 signaling directly. Consequently, overexpression of GLI1 promotes HCC cells to express and secrete more TGFβ1 and IL-6, and activates hepatic stellate cells in tumor microenviroment to express and secrete more Sulfatase2. Due to the Sulfatase2-positive feedback mentioned above, both Sulfatase2 and GLI1 remain overexpressed in HCC mircoenvironment, by which EMT phenotype of HCC cells is maintained. Another aim of this project is to figure out the anti-HCC effect of OKN007, a Sulfatase2 inhibitor, in vivo in the mouse HCC model. The expected results of this project can contribute to understand the regulatory mechanism and function of Sulfatase2 and GLI1 in HCC microenviroment, and develop a novel targeted reagent for HCC. Therefore, proposed studies here are highly significant in improving understanding of the mechanism of HCC development and laying the groundwork for future testing of much-needed rational strategies for the treatment of HCC.

课题组前期实验证实Sulfatase2和GLI1在肝细胞癌（HCC）中过表达，均被证实促进HCC术后复发和转移，但是两者过表达机制仍不明。本项目通过免疫共沉淀、基因沉默、spheroid 3D细胞培养、转基因小鼠等生物实验，力图证实如下学术假说：HCC肿瘤微环境中Sulfatase2通过释放更多细胞膜表面基质中Shh配体与受体相结合或激活TGFβ1通路，上调GLI1表达。过表达GLI1促使HCC细胞分泌TGFβ1和IL-6，激活周围肝星状细胞分泌Sulfatase2，形成Sulfatase2-GLI1-TGFβ1-Sulfatase2的正反馈通路，维持HCC肿瘤微环境中Sulfatase2过表达，进而导致HCC细胞GLI1高表达，从而维持HCC细胞EMT表型。同时，本项目试图研究Sulfatase2抑制物OKN007在动物体内的抗HCC作用。本项目预期研究结果具有较高的科研意义和临床价值。

肿瘤微环境尤其是肝星状细胞对HCC的发生、发展、转移和复发等生物学行为起着至关重要的调节作用。课题组前期实验证实了Sulfatase2 和GLI1 在肝细胞癌（HCC）中为过表达，具有促进HCC 术后复发和转移的作用，但是其具体机制尚不清楚。本项目通过一系列体外及体内实验证实了HCC细胞和以肝星状细胞为主的肿瘤微环境之间存在着以Sulfatase2、Hedgehog/GLI1、TGFβ1、IL-6/STAT3、PCAF、TIMP-1以及SDF-1等因子为核心的直接或间接作用关系网，并对它们之间的内在作用机制进行了一定的阐释，为与HCC肿瘤微环境相关的研究提供了一定的实验和理论依据，具有较高的科研意义和临床价值。这些因子的单独或相互之间的作用可调节HCC的肿瘤微环境以及HCC的发生发展，具有成为预测HCC 转移和术后复发的标志物和靶向治疗药物的潜能。