抗凝血酶III（AT3）是肝细胞合成的丝氨酸蛋白酶抑制剂，其体内外抗凝作用已有广泛研究，但是其是否具有非抗凝作用尚不清楚。我们初步研究结果发现，人肝癌组织中AT3蛋白表达明显低于癌旁组织；在肝癌细胞中过表达AT3基因能够抑制肝癌细胞生长，本研究首次提出肝细胞内AT3除抗凝外可能具有肿瘤抑制作用，AT3可能为细胞内抑癌基因。进一步通过质谱分析发现AT3可与二十几种蛋白质相互作用，其中与肿瘤密切相关的蛋白包括高迁移率族蛋白1（HMGB1）。实验室前期研究发现，肝癌细胞中HMGB1能够活化Hippo-YAP通路；阻断HMGB1信号通路能够抑制肝癌的生长。我们推测AT3的抗肿瘤作用可能与其调节HMGB1功能相关。本项目拟通过在肝癌细胞中过表达和敲低AT3基因，并结合动物实验，论证AT3的非抗凝作用-肿瘤抑制，并进一步阐明AT3抑制肿瘤的可能分子机制，为肝癌的研究提供新的靶点。

Antithrombin III (AT3) is a serine protease inhibitor synthesized by hepatocytes. Its anticoagulation has been widely studied in vitro and in vivo, but whether it has non-anticoagulant effect is not clear. Our preliminary results showed that the expression of AT3 protein in human hepatocellular carcinoma tissues is significantly lower than that of adjacent tissues; overexpression of AT3 gene can inhibit the growth of hepatocellular carcinoma cells, this study, for the first time, proposed that AT3 in the liver cells may have tumor inhibition function besides anticoagulation, AT3 might acts as a tumor suppressor gene within cells. Further more, we used mass spectrometry and found that AT3 could interact with twenty kinds of proteins, including high mobility group protein 1 (HMGB1), which is closely related to tumor. Our .previous studies found that HMGB1 could activate the Hippo-YAP pathway in hepatoma cells, and blocking the HMGB1 signaling pathway could inhibit the growth of liver cancer. We speculate that the antitumor effect of AT3 may be related to its regulation of HMGB1 function. The aim of this project is to overexpress and knock down the AT3 gene in hepatocellular carcinoma cells, combined with animal experiments, and to demonstrate the non-anticoagulant effect (tumor suppressor) of AT3, and further elucidate the possible antitumor molecular mechanism of AT3, and provide a new target for the research of liver cancer.