肝癌早期预警标志物mir-429在肝癌进展中的功能和分子机制研究

Hepatocellular carcinoma (HCC) is the most prevalent malignant neoplasm of the liver and ranks the third leading cause of cancer-related death worldwide. Due to the lack of effective strategies for early diagnosing, much less predicting HCC occurrence for chronic HBV-carrier or cirrhosis patients, only 30-40 percentage of HCC patients are suitable for surgical resection. About 14% of 5-year survival rate for liver cancer were observed totally, whereas patients diagnosed at an early stage show about 27% of 5-year survival rate after liver resection. Therefore, to discover more powerful and reliable surveillance tools for early diagnosis and prediction would greatly improve the prognosis of patients with HCC, and be necessary for screening people at higher risks for liver cancers..In our previous studies, we investigated circulating miRNAs signatures of time-series plasma samples collected from a large cohort including 28612 healthy and 3070 chronic HBsAg-positive persons. Of significantly differential expressed microRNAs in serum, miR-429 was identified as the candidate predictive and very early diagnostic biomarkers with the predominant performance beyond two world-wide recognized methods, alpha-fetoprotein (AFP) and ultrasound. We also observed the enhanced expression of mir-429 in liver tumor-initiating cells..Our project here plans :.(1)to further confirm the sensitivity and specificity of mir-429 as the predictive biomarker by using a larger samples and DEN-induced rodent model firstly;.(2)to intensively explore the role of mir-429 during the hepatocarcinogenesis (especially for the modulation of tumor-initiating cells, including cell self renewal, proliferation, chemoresistance and tumorigenicity);.(3)to investigate the origination and mechanisms involving in the differential expression of circulating miRNAs; .(4)to thoroughly elucidate the molecular mechanism of mir-429-mediated characteristics manipulation or conversion of T-ICs or hepatocytes..We expect that such information along with established clinical and demographic risk factors would have the potential to lead to personalized risk stratifications and interventions that could benefit the public's health and millions of patients in China.

肝癌是恶性程度极高，预后极差的恶性肿瘤，因此寻找肝癌早期预警标志物和干预靶点是提高肝癌诊疗的关键问题。前期我们对肝癌高发区31682人4年的随访中发现108个新发肝癌患者，通过对这些患者发病前6-12个月血清样本中669个小RNA进行定量检测我们发现多个肝癌高发相关小RNA。其中mir-429在肝癌发病前血清中表达水平显著升高，是候选的肿瘤预警标志物。同时mir-429在肝癌起始细胞（T-ICs）中异常高表达。本课题研究拟结合肝癌队列血清、临床肝癌组织样本以及大鼠诱发肝癌模型，首先明确mir-429作为肝癌早期预警标志物的特异性和有效性；其次从动物、细胞、分子层面研究mir-429在肝癌发生发展（特别是T-ICs的功能调控）中的重要作用，确定mir-429的作用方式，阐明mir-429功能调节靶点及其分子网络机制，在加深我们对肝癌发病机制认识的同时，为肝癌早诊早治提供候选标志物和分子靶点。

肝细胞性肝癌（HCC）是肝脏最常见的恶性肿瘤，占世界范围内癌症相关死亡的第三位。由于利用现有的肝癌诊断方法大多数肝癌患者被确诊时已为晚期，导致其5年生存率低至10％-15％，所以对癌症发生的早期预测和早期检测对于选择有效的治疗方法来说至关重要。通过队列筛查，本研究首次发现循环miR-429 和 miR-193a-3p可以作为监测HBsAg-阳性病人发生HCC风险的指标。肝肿瘤起始细胞（T-ICs）来源的miR-429能够在体内和体外水平通过直接靶向抑癌基因RBBP4而促进肝T-ICs的自我更新、增殖和化疗抵抗，并且，我们证实在1p36区域miR-200b/200a/429小RNA簇上游CpG岛低甲基化状况是导致肝T-ICs中miR-429高表达的原因。另外我们还发现miR-200b/miR-200a/miR-429 miRNA簇上游CpG岛的异常低甲基化修饰促进miR-429在肝癌门静脉癌栓中的表达。miR-429能在体外和体内水平通过靶向抑制抑癌基因PTEN提高肝癌转移侵袭能力。此外，我们进一步鉴定了miR-429通过调节PTEN，激活PI3K/AKT信号通路，最终引起β-Cantenin的核转位，实现其促进肝癌转移侵袭的作用，这是miR-429实现对肝癌进展的重要调节机制。我们的结果提示miR-429是预测HCC发生新的监测指标和干预治疗靶点。