髓源抑制细胞（MDSC）促进肿瘤转移的作用和机制研究

发布时间：2018-05-11 20:18

本文选题：肿瘤 + 肿瘤转移　；参考：《东北师范大学》2016年博士论文

【摘要】：肿瘤转移(metastasis)是恶性肿瘤细胞经循环系统从原发部位到达远端组织并继续生长形成转移灶的过程。肿瘤转移不仅需要肿瘤细胞进一步癌变获得迁移运动的能力,还需要机体免疫系统出现异常,无法及时将其清除。研究发现,多种白细胞存在促肿瘤(pro-tumorigenic)表型,能通过多种机制促进肿瘤的病理性演进及转移。其中,髓源抑制细胞(myeloid-derived suppressor cells,MDSC)就是指一类在病理状态下(如肿瘤)增殖和活化并具有免疫抑制能力的异质性细胞群。MDSC分为两个亚型,即粒细胞样MDSC(G-MDSC)和单核细胞样MDSC(M-MDSC)。根据已有报道,MDSC在肿瘤病理性演进的多个阶段(包括肿瘤转移)中发挥促进作用,但两种亚型的MDSC在肿瘤转移过程中所扮演的具体角色尚不明确。为了探讨G-MDSC和M-MDSC分别在肿瘤转移过程中的作用和机制,我们利用流式细胞技术等方法在小鼠肿瘤移植模型中,对外周血中M-MDSC和G-MDSC分别进行了分析,证实了外周血中MDSC的变化与肿瘤的病理性演进密切相关。而且,在肿瘤病理进程中,外周血中M-MDSC增殖先于G-MDSC。我们进一步利用细胞分选、细胞移植和活细胞标记追踪等方法在小鼠肿瘤转移模型中发现,外周血中的G-MDSC和M-MDSC都能促进肿瘤细胞的远端转移。另外,我们分别探讨了循环系统中的G-MDSC促进肿瘤细胞存活过程中的作用机制,以及M-MDSC促进远端组织预转移微环境形成的作用机制。我们通过RT-qPCR分析、体外免疫和CD69膜定位分析等方法,证实了外周血中G-MDSC获得了TAN样活化表型,并能够通过抑制白细胞的活化来减弱肿瘤免疫作用。我们还通过抗体清除、细胞移植、免疫组化和免疫印迹等方法证实肺部募集的M-MDSC促进肺组织中MMP-9的表达。最后,为了确定外周血中M-MDSC检测在临床上的应用前景,我们利用流式细胞技术对临床肿瘤患者外周血中的M-MDSC进行了检测和分析,发现早期肝癌、乳腺癌、宫颈癌患者外周血中M-MDSC的比例上升。我们通过研究发现,M-MDSC能在远端组织募集并参与预转移微环境的形成;外周血中的TAN样活化细胞抑制机体对肿瘤细胞的杀伤;外周血中的M-MDSC比例能针对性的指示一些特定种类癌症的发病。我们的研究揭示了两种亚型的MDSC各自在肿瘤病理条件下的变化情况及它们具体在肿瘤转移过程中发挥作用的环节和机制,对于深入了解MDSC参与肿瘤转移的作用和机制具有重要意义。
[Abstract]:Tumor Metastasis (Metastasis) is a process in which malignant tumor cells pass through the circulatory system from the primary site to the distal tissue and continue to grow to form metastases. Tumor metastasis requires not only the ability of tumor cells to migrate and move further, but also the abnormal immune system, which can not be cleared in time. It has been found that many leukocytes have pro-tumorigenic phenotypes, which can promote the pathological progression and metastasis of tumors through various mechanisms. Myeloid-derived suppressor cells (MDSCs) is a class of heterogeneous cell groups which proliferate and activate in pathological state (such as tumor) and have immunosuppressive ability. MDSC is divided into two subtypes: granulocyte-like MDSC-G-MDSC) and monocyte-like MDSCM-MDSC-like. It has been reported that MDSC plays a promoting role in many stages of tumor pathological progression (including tumor metastasis), but the role of two subtypes of MDSC in the process of tumor metastasis is unclear. In order to investigate the role and mechanism of G-MDSC and M-MDSC in tumor metastasis, M-MDSC and G-MDSC in peripheral blood of mice were analyzed by flow cytometry. It is confirmed that the changes of MDSC in peripheral blood are closely related to the pathological progression of tumor. Moreover, in the pathological process of tumor, M-MDSC proliferation in peripheral blood was prior to that of G-MDSC. We further found that G-MDSC and M-MDSC in peripheral blood could promote the distant metastasis of tumor cells in mice by cell sorting, cell transplantation and living cell marker tracing. In addition, we discussed the mechanism of G-MDSC promoting tumor cell survival in circulatory system and the mechanism of M-MDSC promoting the formation of premetastatic microenvironment in distal tissue. By means of RT-qPCR analysis, in vitro immunoassay and CD69 membrane localization analysis, we confirmed that G-MDSC obtained TAN like activation phenotype in peripheral blood, and could attenuate tumor immunity by inhibiting the activation of leukocytes. We also confirmed that M-MDSC in lung recruitment promoted the expression of MMP-9 in lung tissues by antibody clearance, cell transplantation, immunohistochemistry and immunoblotting. Finally, in order to determine the clinical application prospect of M-MDSC detection in peripheral blood, we detected and analyzed M-MDSC in peripheral blood of clinical tumor patients by flow cytometry, and found early liver cancer and breast cancer. The proportion of M-MDSC in peripheral blood of cervical cancer patients increased. We found that M-MDSC can be recruited in distal tissues and participate in the formation of premetastatic microenvironment, TAN like activated cells in peripheral blood inhibit the killing of tumor cells. The proportion of M-MDSC in peripheral blood can be targeted to indicate the onset of certain types of cancer. Our study revealed the changes of the two subtypes of MDSC in the pathological conditions of the tumor and the mechanisms of their roles in the process of tumor metastasis. It is of great significance to understand the role and mechanism of MDSC in tumor metastasis.
【学位授予单位】：东北师范大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：R73-37

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