COLEC10调控肿瘤自噬在肝细胞癌发生发展中的作用与机制

Collectin subfamily member 10 （COLEC10）, encoding for collectin liver 1 (CL-L1, alias CL-10), belongs to the C-lectin family. COLEC10 possesses classic collagen-like sequences and carbohydrate recognition domains，which function to regulate complement activation or enhance phagocytic phagocytosis via direct agglutinating microorganisms. As a classical mechanism of intracellular energy metabolism and self-renewal, autophagy can suppress or promote tumor development depending on the type and staging of tumor. The relationship between collectins and autophagy remains unknown. Hepatocellular carcinoma (HCC), the most common histological type of liver cancer, is a threatening malignancy due to its high recurrent and metastatic rate. Therefore, effective methods for the diagnosis and prognosis of HCC are of high importance. However, the biomarkers for HCC have long been unsatisfactory in fields of high-risk population screening, early diagnosis and therapeutic evaluation. Hence it is urgent for clinical investigators to identify and characterize novel biomarkers for HCC. By analyzing the TCGA sequencing data, we found that the transcription level of COLEC10 was significantly down-regulated in HCC. Further studies showed that the low expression of COLEC10 was obviously associated with poor prognosis in patients with HCC. Overexpression of COLEC10 not only inhibited the proliferation and metastasis of HCC cells but also supressed the protein level of autophagy marker LC3-II. Whether autophagy functions to promote or suppress HCC has been controversial. It is interesting to explore how COLEC10 regulate autophagy and affect HCC. This topic aims to study: How COLEC10 regulate autophagy in HCC; How COLEC10-mediated autophagy influence the growth and metastasis of HCC. To conclude, this project will provide a scientific basis for establishing COLEC10 as a new prognostic marker and a potential clinical target in HCC.

胶凝素（Collectins）是具有胶原样结构的凝集素, 可通过活化补体发挥调理作用或直接凝集微生物增强吞噬细胞的吞噬作用。而自噬作为经典的细胞内能量代谢和自我更新机制,在不同种类的肿瘤以及肿瘤发展的不同阶段,具有抑制和促进两种对立的影响。目前，胶凝素与自噬的关系尚不明确，而自噬在肿瘤中究竟扮演促癌还是抑癌角色也一直富有争议。我们通过分析TCGA测序发现：胶凝素10（COLEC10)在肝细胞癌（HCC）中的转录水平明显下调。进一步生存分析显示：COLEC10的低表达与HCC患者的不良预后显著相关。过表达COLEC10明显抑制HCC细胞的增殖及转移能力, 并降低自噬标志物LC3-II的蛋白水平。本课题旨在研究：COLEC10在HCC中对自噬的调节及其分子机制；COLEC10调控的自噬对HCC生长及转移的影响及机制。本项目将为明确COLEC10在HCC中的预后价值及作为治疗新靶标提供科学依据。

本课题研究发现COLEC10高表达与肝癌良好预后相关并具有抑制肝癌生长转移的作用。首先，应用多个生物信息学网站明确了COLEC10低表达者生存期较短。通过分子生物学实验及动物实验阐明COLEC10具有抑制肝癌生长和转移的作用。 其次，探索了COLEC10表达受到何种因素调控。 COLEC10表达因启动子甲基化和miR-18a-5p负调控而降低。使用cistrome网站预测COLEC10的转录因子，筛选出ESR1为COLEC10相关性高的转录因子。最后，在机制探索方面，应用蛋白芯片筛选了COLEC10过表达后引起的通路改变，从中鉴定出自噬相关蛋白p32为COLEC10结合蛋白。COLEC10通过促进p32的泛素化降解而抑制自噬，并抑制肝癌生长转移。