基质金属蛋白酶-2对肝癌辐射抵抗的作用及其上游调控机制研究

Radioresistance-mediated local recurrence is the leading cause of treatment failure for patients with HCC after radiotherapy, which has also been a research focus in the field of radiation oncology. Our previous studies indicated that miR-20a could induce radioresistance in HCC cells, and there are putative miR-20a response elements within the 3'UTR of MMP-2 inhibitor TIMP-2 mRNA. Recently, our further findings revealed that MMP-2 levels could be dramatically elevated in established radioresistant HCC cells. Moreover, HCC patients with local recurrence inside the radiation field showed significantly higher MMP-2 expression in their serum and urine samples before radiotherapy as compared to the patients without local recurrence. Thus, we hypothesized that there might be an important correlation between MMP-2 up-regulation and the radioresistant characteristics of HCC; meanwhile, miR-20a might be a potential upstream regulator of MMP-2. In this study, we plan to explore the role of MMP-2 in the induction of HCC radioresistance and its upstream regulatory mechanisms via lentivirus system, reporter gene assay, irradiation of xenotransplantation tumors and detection of MMP-2 in clinical samples, aiming to provide theoretical and experimental bases for uncovering a novel biomarker to predict radiotherapeutic outcome and a new therapeutic target to increase radiosensitivity of HCC patients.

辐射抵抗介导的局部复发是肝癌患者放疗失败的关键因素，也是放射肿瘤学领域的研究热点。我们的前期工作表明，miR-20a能够诱导肝癌细胞产生辐射抵抗，且MMP-2抑制因子TIMP-2 3'UTR存在miR-20a应答元件。近期我们又发现，在肝癌辐射抵抗细胞系中存在MMP-2显著上调；放疗后原位复发的肝癌患者血清与尿液中也呈现MMP-2显著升高。由此我们提出，MMP-2上调与肝癌辐射抵抗可能存在重要关联并受miR-20a间接调控。本项目拟通过慢病毒系统、报告基因系统、动物异位移植瘤照射、临床样本追踪检测等方法，对MMP-2在肝癌中与细胞周期阻滞、辐射抵抗特性的相关性，以及与miR-20a在转录后水平的相互作用进行系统研究，旨在探索MMP-2对肝癌辐射抵抗的作用及其上游调控机制，以期为发现新的预测肝癌放疗疗效的生物标志物及增强肝癌辐射敏感性的治疗靶点提供理论依据和实验基础。

辐射抵抗是导致肝癌患者放疗失败的关键原因。目前已明确，多重促存活信号通路的激活是产生辐射抵抗的核心因素，但其调控的上下游分子机制尚不明确。我们的前期工作表明，肝癌辐射抵抗细胞存在Wnt通路显著激活合并CEMIP基因过度表达，且与肝癌患者的不良预后显著相关。通过本项目我们证实，MMPs家族成员MMP-14可以解除E-cadherin和β-catenin在细胞膜表面的结合状态，促进β-catenin入核，进而上调CEMIP的表达水平，最终介导肝癌细胞辐射抵抗。本项目通过体内外实验及大数据分析，揭示了CEMIP作为肝癌辐射抵抗基因的全新角色，阐明了MMP-14通过β-catenin介导CEMIP相关肝癌辐射抵抗的全新分子机制，为探索新型肝癌放疗增敏剂的精准治疗靶点提供了新的思考角度和临床转化方向。