Miz1在肝脏炎癌转化中的作用及机制研究

Chronic inflammation plays a vital role in the transformation from inflammation to cancer. However, the underlying mechanism is still unknown. We select the common transformation in China from chronic hepatitis, cirrhosis to liver cancer as a model for carcinogenesis from non-resolving inflammation, using hepatocellular carcinoma (HCC) specimens from surgical resection and screening out the key factor Miz1 in the transformation from inflammation to cancer. By constructing the animal model, we found that Miz1 was significantly down-regulated in the oncogenesis and development of HCC, accompying by the increased proliferating and apoptosis. Whereases, pro-inflammatory cytokines, such as IL-1α、TNF-α、IL-6、MCP1, were significantly increased in the process. By using conditional knock out technic we have got liver-specific full-length Miz1 and Miz(∆POZ) knockout mice, further clarification of the mechanism underlying nuclear/cytoplasmic Miz1 in the transformation from inflammation to cancer. These researches are targeting for discovering novel methods in prevention and modulation of carcinogenesis from non-resolving inflammation, and establishing the theory basis for treatment of chronic hepatitis, liver cancer and other chronic diseases.

慢性炎症在炎症性疾病向恶性肿瘤转化中扮演着十分重要的角色，但是促进肝脏炎癌转变的具体机制仍然不得而知。本研究以慢性肝炎、肝硬化向肝癌的转变为突破口，利用手术切除肝癌标本筛选出促进慢性肝炎转化为肝癌的重要因子Miz1。通过构建小鼠炎癌模型发现Miz1在进展为肝癌的过程中其表达是逐渐降低的，同时伴随着增殖和凋亡水平的增高。而促炎因子IL-1α、TNF-α、IL-6、MCP1的表达则是逐渐增多的。进一步的利用组织特异性敲除技术得到肝脏特异性Miz1基因全敲的小鼠Miz1(∆hep)及细胞核内POZ结构域特异性敲除的小鼠Miz1(∆POZ−hep)。拟通过上述基因敲除小鼠阐明Miz1通过细胞浆还是细胞核抑制肝脏非可控性炎症恶性转化的分子机制。本课题的开展将有助于发现干预和控制非可控性炎症恶性转化的新方法，从而为慢性肝炎、肝癌及其它慢性炎症性疾病的治疗打下理论基础。

炎症是原发性肝癌最重要的特征之一，然而，不可控炎症介导的肿瘤发生和发展机制仍是未解之谜。我们这篇研究证明锌指结构转录因子Miz1可以不依赖其转录活性，通过限制NF-κB通路的激活从而抑制原发性肝癌的发生与发展。我们首先通过构建野生小鼠肝癌模型发现Miz1在肿瘤形成之后表达明显降低，进一步构建肝脏特异性Miz1敲除鼠并构建肝癌模型，发现小鼠Miz1全长敲除明显增强了肝脏炎症并恶化了肝癌的进展，而单纯敲除Miz1中有转录活性的POZ功能域后对肿瘤的发生发展无明显的影响。利用高通量测序技术，生物信息学分析联合体外实验验证提示Miz1的敲除可以明显增强TNF-α诱导的P65磷酸化和NF-κB通路的激活。进一步运用免疫共沉淀联合质谱分析揭示Miz1的缺失可以释放与其结合的分子MTDH，被释放的MTDH可以进一步被IKK磷酸化后与P65结合，促进P65的转录活性。利用大量临床原发性肝细胞肝癌样本研究发现Miz1的表达在肿瘤中较癌旁组织明显降低，并与肿瘤病人的预后呈明显的正相关。本研究第一次提出Miz1分子在细胞浆内可以通过限制TNF-α诱导的MTDH的磷酸化以及NF-κB通路的激活从而抑制肝细胞肝癌的发生发展，有可能成为指示预后的指标和治疗肝癌的潜在靶点。