TBX3调控趋化因子表达影响肿瘤微环境的功能和机制研究

Thyroid cancer (TC) is the most common endocrine-related cancer with continuously increasing incidences around 5% per year . Papillary thyroid carcinoma (PTC), derived from thyroid follicular cells, is the most common histology subtype and accounts for 80% of all TC cases. However, the genetic events underlying the initiation and progression of PTC remain largely unknown. Therefore, identification of new molecular targets which will help in early diagnosis and targeted therapy to manage the growth and survival of malignant cells is necessary. Within the tumor micro-environment, inflammatory factors regulate tumor progress through influencing the tumor cell proliferation, angiogenesis, infiltration of immune cells, and so on. In our previous work, TBX3 was found to be highly expressed within PTC samples and promoted tumor cell proliferation. Interestingly, the expression of chemokines including CXCL1,2,8 was significantly decreased when TBX3 was down-regulated within PTC cells, suggesting that TBX3 could be playing critical role in tumor micro-environment. We will perform the following studies: (1) to investigate the influence of TBX3 on chemokines expression and the function of this regulation-axis on tumor cell proliferation, tumor angiogenesis and the immune cell attraction; (2) to find out the molecular mechanism through which TBX3 regulates chemokine expression as well as the function of related molecules in PTC development; (3) check the expression correlation between TBX3 and chemokines as well as angiogenesis, immune cell markers. We will try to understand the biological function of TBX3 in PTC as widely as possible and provide theoretical evidence for its application in the early diagnosis and drug targeting.

甲状腺癌作为内分泌系统最常见的恶性肿瘤，发病率以平均每年5%的速度递增，80%为甲状腺乳头状癌，因而关键致病因子和发病机制以及肿瘤微环境等因素的生物学重要性急需系统的发掘和研究。前期工作提示，转录因子TBX3在甲状腺乳头状癌细胞和组织中过表达，促进癌症发生发展，其水平降低伴随CXCL1，2，8等趋化因子显著下调，暗示TBX3可能参与肿瘤微环境调节。本项目拟在此基础上（1）确定TBX3对趋化因子表达水平的调控，及此调控轴对肿瘤细胞增殖，肿瘤微环境中血管生成，中性粒等免疫细胞招募的影响；（2）探讨TBX3调控趋化因子表达的内在机制及相关因子在癌症发生中的功能；（3）验证临床样本TBX3与趋化因子，血管生成及免疫细胞表型分子的表达相关性。本项目有助于揭示TBX3通过调控趋化因子表达以自分泌和旁分泌方式影响肿瘤微环境及肿瘤发生的生物学功能及分子机制，为其用于癌症早期筛查及药物靶点设计提供理论依据。

近年来，甲状腺癌（Thyroid carcinoma，TC）已经成为全球发病率增长最快的恶性肿瘤之一，然而其发病机制尚不清楚。大多数甲状腺癌患者伴有BRAFV600E突变，那么了解BRAFV600E相关的分子事件，对解析甲状腺癌发生以及靶向治疗具有重要意义。我们前期研究发现，TBX3作为组织发育以及癌症发生密切相关的转录因子，在甲状腺乳头状癌（Papillary thyroid carcinoma ，PTC）组织和细胞系中高表达，并与癌症的恶性程度及淋巴结转移呈正相关。然而内源性TBX3对甲状腺癌发生的影响及其在甲状腺癌中高表达的调控机制尚未可知。.因此，本研究依托小鼠甲状腺癌模型，系统研究TBX3在PTC发生过程中的主要功能，希望以此推进治疗方案的开发。.首先，我们通过杂交甲状腺特异性TPO-Cre转基因小鼠和BrafV600E-Floxed过表达小鼠，建立稳定的先天型原位甲状腺癌模型小鼠（mPTC），采用RT-PCR和Western blot，以及Tbx3-Floxed敲除小鼠，发现Tbx3在BrafV600E-诱导的PTC发生过程中显著增多，受控于BRAF/MAPK通路及AP-1介导的转录激活，而敲除Tbx3阻遏了PTC的肿瘤起始和发展；进而，野生型和Tbx3敲除的小鼠PTC组织转录谱比对，发现Tbx3缺失导致CXCR2-配体类趋化因子显著减少（CXCR2-ligands），包括CXCL1,2,8，分子机制上，发现Tbx3通过NFκB通路促进CXCLs的表达, 功能上，CXCR2-配体相互作用介导Tbx3-促进的肿瘤细胞增殖和肿瘤生长以及骨髓来源的免疫抑制细胞（Myeloid-Derived Suppressor Cells, MDSCs）招募，因此，Tbx3敲除的小鼠PTC组织中MDSCs，尤其是粒细胞性（G-MDSCs）的浸润被显著被抑制；最后，抑制MDSCs浸润有效提高MAPKi对进展型PTC的治疗效果。本项目的研究结果揭示了BRAFV600E -TBX3-CXCLs-MDSCs调控轴在PTC疾病分层及进展预测中的指导意义，并且为提高MAPKi在进展型PTC中的治疗效果提供了思路。