COLEC10通过GRP78抑制肝癌进展的机制研究及其潜在应用

The identification of novel diagnostic and therapeutic targets is the key to improve the clinical outcome of hepatocellular carcinoma (HCC). Recently, by using bioinformatics data mining, large sample of HCC tissue and follow-up patient cohort, we confirmed COLEC10 expression was downregulated in HCC tissue and low level of COLEC10 was significantly correlated with short overall survival, presence of tumor thrombus and high AFP level. COLEC10 overexpression significantly inhibited the proliferation, colony formation and migration abilities of HCC cells in vitro. Through mass spectrometry and immunoprecipitation methods, we demonstrated that COLEC10 interacted with GRP78, activated endoplasmic reticulum stress (ERS) and induced cellular apoptosis in HCC cells. According to the previous study that GRP78 has an important role in cell survival determination via ERS signaling, we hypothesized that COLEC10 could inhibit HCC progression by regulating GRP78 function. However, its molecular mechanism and anti-tumor effect of COLEC10 in HCC are unclear. In this study, we will comprehensively explore the effect of COLEC10 expression on the development and progression of HCC, elucidate the underlying mechanism of COLEC10 blocked binding GRP78 to inhibit HCC, and evaluate its potential application for HCC therapy. The successful completion of this project will clarify the molecular pathway related to HCC progression and provide a scientific basis for discovery of new HCC treatment strategy.

发现和鉴定新的诊疗靶点是改善肝癌临床结局的关键。前期我们利用生物信息数据挖掘、大样本量肝癌病人随访队列发现并证实了COLEC10在肝癌中表达下调，其低表达的肝癌患者总生存时间更短且多个肿瘤指标提示预后不良；过表达COLEC10显著抑制肝癌细胞增殖、平板克隆形成及迁移能力；蛋白质谱及免疫沉淀实验验证了COLEC10与GRP78结合，活化肝癌细胞内质网应激信号并诱导细胞凋亡。鉴于GRP78是内质网应激的重要调控分子，对细胞存活有重要的作用，上述结果提示COLEC10可能通过调控GRP78抑制肝癌进展，但其分子机理及抗肿瘤作用尚未明确。本项目中，我们将全面鉴定COLEC10表达对肝癌发生发展的影响，阐明COLEC10结合封闭GRP78功能抑制肝癌进展的分子机理，并评价靶向COLEC10-GRP78通路在抗肝癌治疗中的作用。项目成功完成将阐明新的肝癌相关分子通路，并为新型诊疗策略研发提供科学依据。

发现和鉴定新的诊疗靶点有助于改善肝癌患者临床结局，而COLEC10已被报道参与肝癌进展调控过程，但具体机制尚未明确。在本研究中，我们利用生物信息数据挖掘及肝癌病人组织队列验证发现COLEC10表达在肝癌中呈普遍下调状态，通过关联分析及生存分析发现COLEC10高表达肝癌病人与更低的AFP值、癌栓阴性显著相关，且这些病人的总生存时间显著延长，表明COLEC10是肝癌病人预后更好的指标之一。我们选取MHCC-LM3和PLC/PRF/5分别建立COLEC10稳定过表达肝癌细胞株，通过体内外肿瘤研究模型证实了COLEC10过表达能显著抑制肝癌细胞的生长和转移能力。机制上，我们发现在内质网中COLEC10通过其C端CRD结构域与GRP78进行相互作用，抑制其与下游内质网应激效应受体PERK、IRE1α结合，后者自磷酸化活化后引起内质网应激反应，CHOP、XBP-1s、ATF4等分子靶标表达升高，从而导致细胞内活性氧水平及细胞凋亡水平升高。联合sorafenib处理时，COLEC10过表达肝癌细胞凋亡水平显著增强，而该效应能被COLEC10-△CRD突变型、内质网应激抑制剂TUDCA或活性氧抑制剂NAC部分抵消，提示干预COLEC10-GRP78信号轴能够增加肝癌细胞对于靶向药物的敏感性。综合上述结果，本研究证实了COLEC10对于肝癌预后诊断和肝癌靶向治疗具有一定的作用，有望为开发新型肝癌诊疗策略提供科学依据。