Zhu Hanzhang, Liu Qiaoyu, Tang Junwei, Xie Yu, Xu Xiaoliang, Huang Ruyi, Zhang Yuanguangyan, Jin Kangpeng, Sun Beicheng
Cell Physiol Biochem. 2017;41(6):2289-2306. doi: 10.1159/000475648. Epub 2017 Apr 26.
BACKGROUND & AIMS: To investigate the expression and prognostic value of α1-ACT (Alpha1-antichymotrypsin) in patients with HCC (hepatocellular carcinoma) and identify the mechanism by which α1-ACT inhibits proliferation and promotes apoptosis of HCC.
We first measured α1-ACT expression levels and determined their relationship with the clinicopathological characteristics and prognosis of patients with HCC.We then established stable HCC cell lines with both α1-ACT overexpression and knockdown and performed a functional analysis in vitro.We first examined the relationship between α1-ACT and the PTEN/PI3K/AKT/mTOR pathway using Western blotting. Then, we determined whether α1-ACT can directly bind to PTEN using co-immunoprecipitation. Finally, we measured α1-ACT expression to evaluate its correlation with the PI3K/AKT/mTOR pathway-related apoptosis proteins in a xenograft tumour mouse model using immunohistochemistry.
The α1-ACT expression level was significantly lower in the HCC tissues than in the paratumour tissues and was negatively positively correlated with the level of Ki67, AFP, the AJCC stage, tumour size and tumour invasion. The overexpression of α1-ACT can inhibit cell proliferation and increase cell apoptosis by activating PI3K/AKT/mTOR-mediated apoptosis via binding to PTEN and activating it in vitro. Additionally, the overexpression of α1-ACT can also increase the proportion of cells in the G0/G1 stage by increasing cyclin p21 expression and inhibiting the migration and invasion abilities of HCC cells by regulating MMP2 and MMP9. The xenotransplantation studies with nude mice also showed that overexpression of α1-ACT inhibited tumourigenesis and knockdown of α1-ACT had the opposite effect.
Our study demonstrates that α1-ACT suppresses liver cancer development and metastasis via targeting the PTEN/PI3K/AKT/mTOR signalling pathway, which may be a potential target for therapeutic intervention in HCC.
研究α1-抗糜蛋白酶（α1-ACT）在肝细胞癌（HCC）患者中的表达及预后价值，并明确α1-ACT抑制HCC增殖和促进其凋亡的机制。
我们首先检测α1-ACT的表达水平，并确定其与HCC患者临床病理特征及预后的关系。然后，我们建立了α1-ACT过表达和敲低的稳定HCC细胞系，并进行体外功能分析。我们首先使用蛋白质免疫印迹法检测α1-ACT与PTEN/PI3K/AKT/mTOR信号通路之间的关系。然后，我们使用免疫共沉淀法确定α1-ACT是否能直接与PTEN结合。最后，我们在异种移植瘤小鼠模型中使用免疫组织化学方法检测α1-ACT的表达，以评估其与PI3K/AKT/mTOR信号通路相关凋亡蛋白的相关性。
HCC组织中α1-ACT的表达水平显著低于癌旁组织，且与Ki67、甲胎蛋白、美国癌症联合委员会（AJCC）分期、肿瘤大小和肿瘤侵袭呈正/负相关。α1-ACT的过表达可通过在体外与PTEN结合并激活它，从而激活PI3K/AKT/mTOR介导的凋亡，进而抑制细胞增殖并增加细胞凋亡。此外，α1-ACT的过表达还可通过增加细胞周期蛋白p21的表达，使处于G0/G1期的细胞比例增加，并通过调节基质金属蛋白酶2（MMP2）和基质金属蛋白酶9（MMP9）来抑制HCC细胞的迁移和侵袭能力。裸鼠异种移植研究还表明，α1-ACT的过表达抑制肿瘤发生，而α1-ACT的敲低则产生相反的效果。
我们的研究表明，α1-ACT通过靶向PTEN/PI3K/AKT/mTOR信号通路抑制肝癌的发展和转移，这可能是HCC治疗干预的一个潜在靶点。
