肝癌微环境中CCL15/16-CCR1轴的生物学意义

The local immune and inflammatory microenvironment, which is strictly controled by chemokine network,play a crucial role in the metastasis and recurrence of hepatocellular carcinoma (HCC). In our priliminary study, after scrutinizing the chemokine network in HCC, we identified that CCL15 and CCL16 expressed in a perticularly high level in HCC tissue, which could not only stimulate HCC cell motility, but also recrute CCR1+CD14+ pro-tumor inflammatory cells, resulting in HCC progression. Based on the above information, in this study, we will first elucidate the cell types in HCC that specifically express CCL15/16 and the cinical significance of CCL15/16. Then, using coculture analysis,specific chemotractant models and mice experiments for intervention, we will emphsis on the biological roles and the underly mechanisms of the "CCL15/16-CCR1 axis" in modulating the local immune and inflammatory microenvironment to a tumor promoting direction, which in turn upregulate the expression levels of CCL15/16 in tumor microenvironment. In addtion, our study will also investigate the effect and the associated molecullar mechnisms of "CCL15/16-CCR1 axis" on HCC cell invasion and metastasis. Modulating "CCL15/16-CCR1 axis" will repress the invasive potential of HCC cells, and re-programme the local immnune resoponse to a anti-tumor direction, leading to reduced HCC recurrence and improve survival.

受趋化因子系统精密调控的炎症/免疫微环境是影响肝癌转移复发的重要因素。我们前期对肝癌微环境中趋化因子进行全面筛查后发现：CCL15、CCL16特异性高表达，可刺激肝癌细胞，招募CCR1+CD14+炎症细胞，促进肝癌进展。本项目将首先明确CCL15/16在微环境的细胞定位及临床意义，进而通过细胞共培养、体内外趋化模拟和干预模型研究，拟阐明："CCL15/CCL16-CCR1轴"所介导的促癌炎症/免疫微环境及后续的放大效应（即：促癌微环境进一步上调CCL15/16表达）是促进肝癌侵袭转移的重要因素，两者之间存在以"微环境细胞因子网络"为链接的正反馈；同时，"CCL15/CCL16-CCR1轴"可直接影响肝癌细胞本身的侵袭特性。调控CCL15/CCL16表达，或利用CCL15/CCL16的趋化特性，打破这一恶性循环有助于降低/逆转肝癌侵袭潜能，同时恢复肿瘤微环境的抗癌反应，减少肝癌复发。

肝细胞肝癌（简称肝癌）是一种侵袭性较高的恶性肿瘤，临床上预后较差。越来越多的研究表明，肿瘤微环境在肿瘤的发展中起着重要的作用。肝癌是典型的炎症相关性肿瘤，慢性炎症的肿瘤微环境有助于肝癌的生长及转移。趋化因子及其受体细胞是肿瘤微环境的重要组成部分，不同类型的趋化因子及其受体在肿瘤的进程中扮演者不同的角色。我们前期通过SABioscience公司的趋化因子表达谱芯片发现，在7种人肝癌细胞系（Hep3B、MHCC97L、MHCC97H、HCCLM3、PLC、SMMC-7721、Huh7）和12例人肝癌组织的趋化因子表达谱中，表达水平都较高的是CCL15。本课题研究发现，肝癌病人外周血CCL15含量明显高于乙肝后肝硬化、乙肝病人及正常人群，肝癌组织中CCL15表达也明显高于对应癌旁组织。细胞流式分析和免疫荧光结果表明，肝癌组织中异常高表达的CCL15可趋化外周血中CCR1+的细胞至肿瘤病灶周围，并且其表型主要为CD14+单核细胞。免疫组化结果发现，CD14+单核细胞主要集中于癌交界区，癌内及癌旁分布较少。癌交界区CD14+单核细胞数量与肿瘤恶性临床病理特征及不良预后显著相关，并且是肿瘤预后的独立危险因素。人肝癌组织分离得到CD14+单核细胞，与肿瘤细胞共培养后上清中多种细胞因子表达明显增加，体外功能实验表明共培养后的上清可以促进肿瘤细胞的增殖和侵袭。细胞信号通路芯片检测共培养后的肿瘤细胞发现，其胞内Jak2-STAT3-Akt信号通路被激活。裸鼠肝癌原位模型实验表明，CCR1拮抗剂可以显著抑制原位肿瘤的生长，并且降低其肺转移能力。因此，鉴于CCL15-CCR1轴对肝癌生长和转移的重要促进作用，其可能是肝癌潜在的有效治疗靶点。