Department of Hepatobiliary Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, 277 Yanta West Road, Xi'an, Shaanxi Province, 710061, China.
J Exp Clin Cancer Res. 2019 Apr 18;38(1):170. doi: 10.1186/s13046-019-1163-6.
Cancer stem cells (CSCs) require stromal signals for maintaining pluripotency and self-renewal capacities to confer tumor metastasis. Resolvin D1 (RvD1), an endogenous anti-inflammatory lipid mediator, has recently been identified to display anti-cancer effects by acting on stroma cells. Our previous study reveals that hepatic stellate cells (HSCs)-derived cartilage oligomeric matrix protein (COMP) contributes to hepatocellular carcinoma (HCC) progression. However, whether RvD1 inhibits paracrine of cancer-associated fibroblasts (CAFs)-derived COMP to prevent epithelial-mesenchymal transition (EMT) and cancer stemness in HCC remains to be elucidated.
CAFs were isolated from HCC tissues. Direct and indirect co-culture models were established to analyze the interactions between HCC cells and CAFs in the presence of RvD1 in vitro. The transwell and tumor sphere formation assays were used to determine invasion and stemness of HCC cells. The subcutaneous tumor formation and orthotopic liver tumor models were established by co-implantation of CAFs and HCC cells to evaluate the role of RvD1 in vivo. To characterize the mechanism of RvD1 inhibited paracrine of COMP in CAFs, various signaling molecules were analyzed by ELISA, western blotting, reactive oxygen species (ROS) detection, immunofluorescence staining, dual luciferase reporter assay and chromatin immunoprecipitation assay.
Our data revealed that RvD1 treatment can impede the CAFs-induced cancer stem-like properties and the EMT of HCC cells under co-culture conditions. In vivo studies indicated that RvD1 intervention repressed the promoting effects of CAFs on tumor growth and metastasis of HCC. Furthermore, RvD1 inhibited CAF-induced EMT and stemness features of HCC cells by suppressing the secretion of COMP. Mechanistically, formyl peptide receptor 2 (FPR2) receptor mediated the suppressive effects of RvD1 on COMP and forkhead box M1 (FOXM1) expression in CAFs. Notably, RvD1 impaired CAF-derived COMP in a paracrine manner by targeting FPR2/ROS/FOXM1 signaling to ultimately abrogate FOXM1 recruitment to the COMP promoter.
Our results indicated that RvD1 impaired paracrine of CAFs-derived COMP by targeting FPR2/ROS/FOXM1 signaling to repress EMT and cancer stemness in HCC. Thus, RvD1 may be a potential agent to promote treatment outcomes in HCC.
癌症干细胞（CSCs）需要基质信号来维持多能性和自我更新能力，从而赋予肿瘤转移的能力。解析素 D1（RvD1）是一种内源性抗炎脂质介质，最近被发现通过作用于基质细胞来显示抗癌作用。我们之前的研究表明，肝星状细胞（HSCs）衍生的软骨寡聚基质蛋白（COMP）有助于肝细胞癌（HCC）的进展。然而，RvD1 是否抑制癌相关成纤维细胞（CAFs）衍生的 COMP 的旁分泌作用以防止 HCC 中的上皮-间充质转化（EMT）和癌症干性仍有待阐明。
从 HCC 组织中分离出 CAFs。建立直接和间接共培养模型，以分析 HCC 细胞与 RvD1 存在下体外 CAFs 之间的相互作用。Transwell 和肿瘤球体形成测定用于确定 HCC 细胞的侵袭和干性。通过共植入 CAFs 和 HCC 细胞建立皮下肿瘤形成和原位肝肿瘤模型，以评估 RvD1 在体内的作用。为了表征 RvD1 抑制 CAFs 中 COMP 旁分泌的机制，通过 ELISA、western blot、活性氧（ROS）检测、免疫荧光染色、双荧光素酶报告基因测定和染色质免疫沉淀测定分析各种信号分子。
我们的数据表明，RvD1 处理可以在共培养条件下阻止 CAFs 诱导的 HCC 细胞的癌症干性样特性和 EMT。体内研究表明，RvD1 干预抑制了 CAFs 对 HCC 肿瘤生长和转移的促进作用。此外，RvD1 通过抑制 COMP 的分泌抑制 CAF 诱导的 HCC 细胞的 EMT 和干性特征。在机制上，甲酰肽受体 2（FPR2）受体介导了 RvD1 对 CAFs 中 COMP 和叉头框 M1（FOXM1）表达的抑制作用。值得注意的是，RvD1 通过靶向 FPR2/ROS/FOXM1 信号以破坏 FOXM1 募集到 COMP 启动子，从而以旁分泌方式损害 CAF 衍生的 COMP。
我们的结果表明，RvD1 通过靶向 FPR2/ROS/FOXM1 信号抑制 EMT 和 HCC 中的癌症干性，损害 CAFs 衍生的 COMP 的旁分泌。因此，RvD1 可能是促进 HCC 治疗效果的潜在药物。
