CCL18调控上皮代谢重编程促进白斑组织“酸化”的机制研究

Accumulating evidence has suggested tissue acidosis is actively engaged in a number of human key diseases , which is characterized by the metabolic reprogramming. Oral leukoplakia is the most common precancerous lesion of the oral mucosa. Recently, we demonstrated that the amounts of macrophages and the expression of Chemokine (C-C motif) ligand 18 (CCL18) were up-regulated in the carcinogenesis of oral leukoplakia. Our previous studies showed that CCL18 induced enhanced expression of the key glycolytic enzyme lactate dehydrogenase A (LDHA), and increased the colony formation of oral epithelial cells in vitro. Therefore, we hypothesize that in oral precancerous microenvironment, CCL18 secreted by macrophage induces aerobic glycolysis of epithelial cells and drives acidosis in the microenvironment, which will therefore induces the epithelia malignant transformation. To address this hypothesis, we will elucidate the exact mechanisms in which CCL18 induces epithelia malignant transformation via mediating epithelial cell metabolism imbalance. The clinical correlation between severity of precancerous lesion and expression of CCL18/LDHA were also been examined. All these findings would be helpful to elucidate the exact molecular mechanisms of oral epithelia malignant transformation and provide novel therapeutic targets for oral precancerous lesion.

酸性微环境形成（acidosis）是多种重大疾病代谢重编程的核心环节之一。申请人前期研究发现：在口腔白斑的演变过程中，巨噬细胞浸润增多、其分泌的CCL18显著升高，CCL18作为趋化因子可上调糖酵解通路关键酶乳酸脱氢酶A（LDHA）的表达、增强上皮细胞克隆形成能力，强烈提示巨噬细胞分泌的CCL18可以增强上皮细胞糖酵解、促进上皮细胞的恶性转化。由于微环境酸化是巨噬细胞极化的重要推手，我们认为口腔白斑演变的过程中，存在着巨噬细胞分泌CCL18-上皮细胞代谢重编程-组织微环境酸化-促进巨噬细胞极化的作用环路。为此，本项目拟利用体外培养、小鼠模型和临床标本获得巨噬细胞分泌CCL18促进白斑演进的直接证据，阐明CCL18调控代谢重编程，促进细胞外环境酸化的分子机制，分析该机制与白斑转归的关系，为阐明口腔白斑癌变机制提供新的重要证据和防治靶点。

研究表明酸性微环境形成(acidosis)是多种重大疾病代谢重编程的核心环节之一。在口腔癌前病损口腔白斑病的发生发展中，出现了局部炎症浸润和代谢重编程。然而，其作用机制和意义尚未明确。我们首先检测了CCL18对DOK、OSCC增殖、迁移、侵袭的影响及对细胞糖酵解的调控作用，发现CCL18通过激活PI3K/Akt信号通路，促进DOK、OSCC细胞的糖酵解途径，促使乳酸生成增多，形成酸性细胞外环境，从而促进DOK、OSCC细胞增殖，诱导细胞的迁移、侵袭能力增强。进一步构建了4NQO诱发小鼠舌黏膜癌变模型，观察CCL18介导的细胞代谢重编程对口腔白斑发生发展的调控作用，结果显示CCL18促进小鼠舌黏膜的恶性转化，成瘤率增加，病损组织中LDHA蛋白表达升高。此外，与正常上皮细胞相比，表达CCL18的OSCC细胞来源的凋亡囊泡促进OSCC细胞生长，诱导细胞中糖酵解关键酶PKM2、LDHA蛋白表达升高，而间充质干细胞来源的细胞外凋亡囊泡则表现为抑制肿瘤的生长，为肿瘤的治疗提供了一种潜在的无细胞治疗策略和新的载体。总之，CCL18通过调控上皮细胞代谢重编程，促进细胞外环境酸化，从而最终促进上皮的恶性转化，为口腔白斑防治提供潜在的新策略。