低氧上调肝癌血管内皮细胞DGKG激活整合素介导的ECM/FAK/YAP通路促进免疫逃逸的机制研究

近来，肝癌免疫治疗展现了一定潜力，但治疗反应率仍不令人满意，更好地了解肝癌免疫抑制微环境中各成分之间的串扰，有助于挑选潜在治疗靶点。申请人通过表达谱芯片筛选出DGKG在肝癌血管内皮细胞特异性高表达且与不良预后相关；体内外实验均证实肝癌内皮细胞DGKG在促进肿瘤免疫逃逸中发挥不可忽视的作用。低氧是肝癌恶性表型的驱动因素，会触发一系列免疫抑制过程，本研究发现低氧诱导因子HIF-1α转录调控DGKG具有细胞特异性。机制研究表明DGKG通过激活整合素介导的ECM/FAK/YAP通路，导致免疫抑制细胞因子TGF-β分泌增多，诱导免疫抑制微环境形成。本研究拟从人群样本、DGKG内皮特异性敲除鼠、细胞层面，运用3D共培养、多色免疫荧光、蛋白芯片等技术证实以上假说。这为肝癌免疫抑制微环境预测标志物及治疗靶点探索提供了科学依据，而针对肝癌血管内皮细胞DGKG的干预治疗有望为肝癌精准化诊治提供新策略。

Recently, immunotherapy was developed for the treatment of hepatocellular carcinoma (HCC) with considerable effect. However, the response rate is still not satisfactory. Extensive efforts are underway to identify the mechanism underlying the crosstalk in the immunosuppressive microenvironment of HCC, which is helpful to provide a promising therapeutic strategy. We found that endothelial DGKG expression is enhanced in HCC and correlates with poor prognosis in HCC patients. A series of experiments in vivo and in vitro have confirmed that endothelial DGKG expression plays a vital role in promoting tumor immune escape. Tumor hypoxia, which is a driver of the malignant phenotype of HCC, triggers a variety of immunosuppressive processes. Here, we found that hypoxic inducible factor HIF-1α has a cell-specific transcriptional regulation of DGKG. Further investigation revealed that DGKG promotes immune escape through integrin-mediated ECM/FAK/YAP signaling, leading to increased secretion of immunosuppressive cytokine TGF-β and inducing the immunosuppressive microenvironment. We employed 3D co-culture, multiplex immunohistochemistry and protein microarray to confirm the above hypothesis using HCC samples, EC-specific DGKG conditional knockout mice and Human Umbilical Vein Endothelial Cells.Our study provides a scientific basis of immunosuppressive microenvironment predictive markers and therapeutic targets of HCC, and the treatment aiming at vascular endothelial cells DGKG is expected to provide a new strategy for the precise diagnosis and treatment of HCC.