慢性炎症触发结肠癌"Warburg"效应的发生及机制研究

Cancer cells preferentially metabolize glucose through aerobic glycolysis. This phenomenon, known as the Warburg effect, is an anomalous characteristic of glucose metabolism in cancer cells. Previous study disclosed that the Warburg effect was induced by hypoxia and Mitochondrial deficiency. In fact, aerobic glycolysis is established in cancer cells before hypoxia on the early stage of tumorigenesis. Chronic inflammation is a key promoting factor of tumourigenesis. It remains, however,largely unexplored whether and how pro-tumourigenic inflammation regulates glucose metabolism in cancer cells. In this study, we intend to study the relationship of chronic inflammation and the Warburg effect. Firstly, the colitis associated cancer mouse model will be built and the levels of genes related to aerobic glycolysis in tumor also will be detected. Secondly, cancer cells glucose consumption, oxygen consumption and lactate production, as well as the levels of genes expression will be tested after treatment with interleukin-6(IL-6). After that, the levels of phosphorylated STAT3 would be explored if the associated pathway could be activated by IL-6. The phosphorylated STAT3, as a transcription factor, could bind to the cis-element of genes and eventually promote the genes transcription, which contributes to trigger the Warburg effect. Moreover, culture the cancer cells in oxygen limited condition after treatment with IL-6, and that could increase the expression of hypoxia inducible factor-1α(HIF-1α), which would further promote aerobic glycolysis in cancer cells.

"Warburg"效应(有氧糖酵解)是恶性肿瘤代谢的特征，既往认为是由缺氧和线粒体功能障碍引起，最近研究表明，在肿瘤形成的初期，缺氧尚未发生时，有氧糖酵解已存在。而慢性炎症是诱导肿瘤发生进展的重要原因，因此，慢性炎症与有氧糖酵解是否有某种内在的联系？我们首先建立慢性炎症诱发的小鼠结肠癌模型，检测慢性炎症在诱发肿瘤的同时对糖酵解途径相关基因表达的影响；其次用IL-6+重组人sIL-6R刺激结肠癌细胞，研究其对肿瘤细胞葡萄糖代谢的影响，并检测其对上述糖酵解基因表达的影响；接着在结肠癌细胞株研究IL-6能否激活下游信号通路，导致STAT3磷酸化，并研究STAT3能否通过与靶基因转录调控元件结合，促进基因转录，从而引发"Warburg"效应；随着肿瘤的进展，缺氧可诱导HIF-1α的表达，HIF-1α和STAT3可能通过形成co-factors或分别结合到靶基因的调控元件，协同促进有氧糖酵解的发生。

背景：“Warburg”效应(有氧糖酵解)是恶性肿瘤代谢的特征，既往认为是由缺氧和线粒体功能障碍引起，研究表明，在肿瘤形成的初期，缺氧尚未发生时，有氧糖酵解已存在。而慢性炎症是诱导肿瘤发生进展的重要原因，因此，慢性炎症与有氧糖酵解是否有某种内在的联系？.主要研究内容：(一)采用化学法（AOM+DSS）建立小鼠结肠癌模型，初步判断在结肠癌发生过程中IL-6对“Warburg”效应关键基因表达水平的影响。(二)研究IL-6对结肠癌细胞葡萄糖代谢及糖酵解相关基因表达的影响。(三)探索IL-6引起“Warburg”效应发生的分子机制。.重要结果和关键数据：1）在AOM+DSS诱导的小鼠结肠癌模型中，用IL-6单抗阻断IL-6通路后可以显著抑制结肠癌的肿瘤形成以及“Warburg”效应关键基因的表达。在早期腺瘤形成阶段即已经出现PFKFB3基因的明显下调，提示IL-6通过调节“Warburg效应”关键基因促进结直肠癌的发生发展，在结直肠癌形成的早期腺瘤阶段，IL-6可能主要通过调节PFKFB3基因起作用。2）PFKFB3在人结直肠腺瘤和腺癌组织中均高表达且和淋巴结转移、脉管内癌栓和TNM分期相关。提示PFKFB3在人的结直肠癌发生发展过程中发挥了重要作用。3）IL-6可以在细胞水平促进SW480细胞的葡萄糖消耗率和乳酸生成率，并上调包括PFKFB3基因在内的“Warburg效应”关键基因的表达。即IL-6可以在细胞水平促进“Warburg效应”的发生。4）阻断IL-6通路在腺瘤和腺癌中HIF-1α在mRNA和蛋白水平均明显下降。此外，HIF-1α在结肠癌患者癌组织中是高表达的，并且HIF-1α表达水平和患者血浆IL-6浓度呈正相关。提示HIF-1α可能也是IL-6介导的促进“Warburg效应”的重要中间介导因子之一。.科学意义：本研究通过一些列研究证实了慢性炎症（IL-6）可以通过促进结肠癌“Warburg效应”的发生而促进结直肠癌的发生发展，并且PFKFB3基因和HIF-1α在其中发挥了重要作用，为临床上防治结肠癌的发生发展提供了新思路。