肿瘤干细胞钙信号在肝再生相关分泌蛋白SAA1影响肝癌侵袭转移中的机制研究

The postoperative recurrence has been the research interest and challenge in hepatocellular carcinoma (HCC), and clinical studies have shown that the cytokines related to postoperative liver regeneration are closely associated with HCC recurrence, however, the mechanism is unknown. Based on the powerful effect of ALPPS on postoperative liver regeneration of HCC, the applicant found the secreted protein SAA1 increased significantly in serum and liver regenerated tissues of postoperative patients with ALPPS, and further observed that the signals related to cancer stem cells (CSCs) and calcium were activated significantly. Previous study suggests SAA1 promotes the cancer invasion and metastasis significantly, could regulate the adhesion and migration of inflammatory cells by increasing calcium influx. Also, the applicant found the critical role of CSCs in HCC recurrence (Hepatology, 2016). Therefore, we hypothesized that SAA1 promoted HCC recurrence via regulating the calcium signal of CSCs. To further clarify: 1) the relationship of SAA1 and HCC prognosis; 2) the mechanism of the effect of secreted protein SAA1 on the biological behavior of liver cancer stem cell and its calcium signal; 3) the function and mechanism of CSCs calcium signal in the effect of SAA1 on the invasion and metastasis of HCC. With the important clinical value, expected achievement will help to understand the impact of postoperative liver regeneration on the recurrence of HCC.

肝癌术后复发一直是研究的热点和难点，多项临床研究显示肝癌术后肝再生相关细胞因子与肝癌复发密切相关，但目前机制不明。申请人前期研究基于肝癌ALPPS术后肝脏快速再生的特点，以ALPPS为研究模型，发现肝再生分泌蛋白SAA1在术后患者血清中和肝再生组织中呈高表达，继而发现肿瘤干细胞信号与钙信号被显著激活。报道显示，SAA1可以显著促进肿瘤的侵袭转移，并通过增加钙离子内流调控炎症细胞的粘附迁移。结合申请人前期发现肿瘤干细胞在肝癌复发中起重要作用（Hepatology, 2016），据此，我们推测SAA1通过调控肿瘤干细胞钙信号促进了肝癌术后复发。拟进一步阐明：1）SAA1与肝癌预后的相关性；2）SAA1对肝癌干细胞生物学行为及其钙信号影响的分子机制；3）肿瘤干细胞钙信号在SAA1影响肝癌侵袭转移中的作用及分子机制。预期结果将有助于理解肝癌术后肝再生对肝癌复发的影响，具有重要临床价值。

我国是乙肝大国，乙肝相关性肝癌严重威胁国人的健康。肝癌术后复发转移是肝癌治疗面临的重大难题，寻找能够预警肝癌术后复发的生物标记物具有重要临床应用价值。鉴于参与肝再生及炎症的相关分子在肝癌发生发展中的重要作用，我们前期筛选到再生及炎症相关分子SAA1，本项目明确了SAA1在肿瘤组织中高表达可显著促进肝癌术后的复发转移，并降低了总体生存率水平。SAA1的敲低可显著抑制肝癌肿瘤细胞的侵袭转移，且促进SAA1的表达可显著增加肿瘤细胞胞浆及线粒体中的钙流信号水平。由于SAA1在门静脉癌栓组织（PVTT）中显著高表达，我们专门针对伴有PVTT的HCC患者构建了术后个体化评分系统，用于指导此类患者术后的治疗及随访。另外，鉴于我国肝癌患者大都是乙肝相关性肝癌，我们考虑SAA1与肝癌之间的密切关系，很有可能是基于乙肝性肝癌的背景。接下来，我们针对乙肝相关性肝癌研究发现，相对于HBX-WT，HBX-E2基因型的乙肝肝癌患者具有更好的预后，进一步明确了此类患者术后高复发人群,为加强对此类患者的术后随访提供坚实依据。同时，我们团队发现血清HBV-pgRNA可增强肝癌细胞的干性以促进肿瘤发展，且可作为HBV相关肝癌术后复发的预测因子，为HBV-DNA阴性患者提供了有效的风险预测及治疗指标。