DNAse1L3促进原发性肝癌细胞凋亡的分子机制研究

In the previous study, we found that DNAse1L3 had the effect of inhibiting the growth of liver cancer cells, but the mechanism is unknown. We found that the gene was downregulated in primary hepatocellular carcinoma (HCC), and the prognosis was significantly worse than that of normal expression. Overexpression of DNAse1L3 significantly promoted hepatocellular carcinoma cell apoptosis, and significantly reduced the drug resistance of hepatoma cells. In preliminary experiments, we found that the gene regulates the expression of key molecules in the hippo pathway. Therefore, this gene may inhibit the growth of hepatoma cells and promote its apoptosis by acting on Hippo pathway. Our research will focus on: 1. To expand the sample size, analyze the clinical significance of DNAse1L3 down-regulation in HCC samplers; 2. To study the tumor-supressor function of DNAse1L3 in vitro and in vivo; 3. To study the mechanism of DNAse1L3 in regulating cell proliferation and apoptosis, and ultimately achieve the occurrence and development of primary liver cancer in-depth exploration and understanding.

前期研究中我们发现DNAse1L3具有抑制肝癌细胞生长的作用，但作用机制不明。我们发现该基因在原发性肝癌组织里表达下调，预后较表达正常者明显较差。过表达DNAse1L3显著促进肝癌细胞凋亡，并且显著降低肝癌细胞的耐药性。预实验中我们发现该基因调控hippo通路中关键分子的表达，因此该基因可能通过作用于Hippo通路抑制肝癌细胞的生长，促进其凋亡。我们的研究将围绕：1. 扩大样本量，分析DNAse1L3在原发性肝癌样本中下调的临床意义；2. 从体内、体外进行DNAse1L3的抑癌功能实验研究；3. 进行DNAse1L3对细胞增殖以及凋亡调控机制研究,最终实现对原发性肝癌发生、发展机制的深入探索和了解。

前期研究中我们发现脱氧核糖核酸酶家族成员（Deoxyribonuclease 1 like 3, DNAse1L3）表达水平在多种类型的胃肠道肿瘤，特别是在肝细胞癌（Hepatocellular carcinoma, HCC）中显著下调。DNAse1L3是一种染色质结合的钙、镁离子依赖性核酸内切酶，体外实验显示重组DNAse1L3能将DNA切割成高分子量的核苷酸片段或者寡核苷酸片段，提示DNAse1L3可能参与调控肿瘤细胞的增殖和凋亡。虽然抑制核苷酸内切酶参与了凋亡细胞DNA片段化的过程，但是对于其机制还知之甚少，有关DNAse1L3与肝脏肿瘤的关系的研究更是空白。我们对TCGA的肝癌数据进行预后分析证明DNAse1L3表达水平与肿瘤大小（P=0.0028）、肿瘤血栓形成（P<0.01）以及病人较差的总生存期（P=0.005）和无病生存期（P=0.006）呈显著相关。富集分析发现DNAse1L3的表达水平与补体激活相关，进一步研究标明，在肝癌细胞系中过表达DNAse1L3，并给C3a受体激动剂处理后，DNAse1L3过表达显著抑制了肿瘤细胞生长和PI3K/AKT信号通路的激活。本项目首次表明，DNAse1L3可能作为肝癌患者预后的生物标记物，并通过抑制补体激活后的PI3K/AKT信号通路激活，进而抑制肝癌细胞生长。