食管癌化HUVECs疫苗联合基于PDX模型的个体化DCs瘤苗抗食管鳞癌研究

Tumor immunotherapy is an important, prosperous and new mode of tumor therapy. Solid tumor mainly consists of tumor cells and blood vessels. The therapeutic effect of a single anti-tumor cells or anti-angiogenesis therapy is limited. So, combined immunotherapy is imperative. Our preliminary research showed that the vaccine of endothelial cells inhibited tumor growth by suppressing tumor angiogenesis. However, this kind of vaccine still need to be optimized. We also have demonstrated that the vaccine of dendritic cells (DCs) has significant effect on anti-esophageal squamous carcinoma. However, the problem is the volum of esophageal carcinoma is quite small, therefore, it’s very difficult to get individualized antigen. Based on these preliminary researches, human umbilical vein endothelial cells (HUVECs) will be induced by tumor microenvironment of esophageal squamous carcinoma, to make the quality of HUVECs similar to tumor endothelial cell to play more important role in anti-tumor angiogenesis. Meanwhile, esophageal carcinoma cell will be amplified by PDX (patient-derived xenograft, PDX) model of SCID (severe combined immune deficiency, SCID) mice, to prepare individualized tumor cell/DCs fusion vaccine to kill tumor cells. The combination of two kinds of vaccine will kill both tumor cells and tumor vascular endothelial cells, to make powerful anti-tumor effect, which might present a good applied prospect in immunotherapy of anti-esophageal squamous carcinoma.

肿瘤免疫治疗是一种重要的、正在迅速发展的肿瘤治疗新模式。实体肿瘤主要由肿瘤细胞及肿瘤血管构成，单一抗肿瘤细胞、或单一抗血管生成的免疫治疗效果有限，联合免疫治疗势在必行。我们前期利用内皮细胞疫苗靶向抑制肿瘤血管生成，产生一定效果，但疫苗仍需优化；前期也采用树突状细胞（dendritic cells，DCs）疫苗抗食管鳞癌治疗，存在问题是食管癌患者标本体积小，个体化抗原获取困难。本项目拟在前期研究基础上，模拟食管鳞癌微环境诱导脐静脉内皮细胞，使其接近肿瘤血管内皮细胞特性，提高该疫苗抗肿瘤血管生成的靶向性；同时，构建人食管鳞癌PDX（patient-derived xenograft，PDX）模型，利用SCID小鼠体内扩增患者食管鳞癌组织细胞，制备个体化肿瘤细胞与DCs的融合疫苗，靶向杀伤肿瘤细胞。两种疫苗联合应用产生更强的抗癌效应，该策略有望成为具有良好应用前景的抗食管鳞癌免疫治疗新方案。

肿瘤免疫治疗是一种重要的、正在迅速发展的肿瘤治疗新模式。实体肿瘤主要由肿瘤细胞及肿瘤血管构成，单一抗肿瘤细胞、或单一抗血管生成的免疫治疗效果有限，联合免疫治疗势在必行。本项目首先研究了脐静脉内皮细胞（HUVEC）疫苗对食管鳞癌的抑制效果。对NOD/SCID小鼠进行免疫重建，发现HUVEC疫苗发挥了明显抑制食管鳞癌生长及抗血管生成效应。但HUVEC是正常的内皮细胞，它与肿瘤血管内皮细胞（TEC）有很大差异，需要对该疫苗进行优化。采用食管鳞癌细胞培养上清制备的条件培养基诱导HUVEC，发现诱导后HUVEC的迁移、侵袭、小管形成以及Dil-Ac-LDL摄取功能增强，高表达TEC特异性标志（TEM1、TEM8），表明诱导后HUVEC具备TEC特性（称“肿瘤化HUVEC”）。动物实验证明，与HUVEC疫苗相比，肿瘤化HUVEC疫苗抑制肿瘤生长、抗血管生成能力均明显增强。基因表达谱芯片结果进一步表明，c-Myc在HUVEC向TEC转变过程中起关键作用，JAK/STAT3信号通路参与此过程。二甲双胍可以通过抑制JAK/STAT3/c-Myc信号，从而抑制该转变发挥抗血管生成作用，并在建立的人食管鳞癌PDX模型中证明了二甲双胍的抗血管生成作用。. 树突状细胞（DC）在体内可激活初始T淋巴细胞，产生CTL杀伤肿瘤细胞。本研究发现负载自身肿瘤组织裂解物的DC反而促进肿瘤血管生成，可能由于肿瘤组织匀浆含有抑制DC功能的细胞因子，诱导其内皮样分化从而促进血管生成。鉴于该方法制备的DC疫苗已有临床应用，此研究结果对其安全性具有警示意义。基于此，该项目后续研究中抗原的制备采用肿瘤细胞冻融裂解物，离心去除上清中可能抑制DC功能的细胞因子。结果表明该DC疫苗联合肿瘤化HUVEC疫苗对移植瘤的抑制、对肿瘤血管生成的抑制作用均优于单疫苗组。联合疫苗组小鼠血清中肿瘤血管生成相关抗体水平、脾指数、CTL杀伤效应、IFN-γ水平、脾脏及肿瘤组织中浸润的CD3+CD8+T淋巴细胞数均高于单疫苗组。该项目采用肿瘤化HUVEC疫苗联合DC疫苗，既杀伤肿瘤细胞，又产生抗肿瘤血管效应，该策略有望成为具有良好应用前景的抗肿瘤免疫治疗新方案。