RARγ在慢性炎症诱发胆管上皮细胞糖代谢紊乱中的上下游调控机制

The JAK/STAT3 signaling pathway plays a provital role in the malignant transformation of cholangiocytes induced by biliary tract chronic inflammation. However, the mechanisms remain unclear. Our preliminary experiments showed that long time stimulation of IL-6 induced RARγ overexpression through activation of JAK/STAT3 signaling pathway. In addition, RARγ could directly interact with SOCS1 and then promote STAT3 reactivation. Overexpression of RARγ prompted IL-6 to continuously activate JAK/STAT3 signaling pathway and induced glycose metabolism disorders of cholangiocytes. Therefore, our project was designed to investigate how the interaction of RARγ with SOCS1 to break the negative regulation of JAK/STAT3 signaling pathway mediated by SOCS1 via promoting the proteasome degradation by ubiquitination of SOCS1 and inhibiting the interaction of SOCS1 with JAK, and then mediates the continus activation of IL-6/STAT3/Snail signal axis. Finally, to confirmation the role and mechanism of RARγ in regulating IL-6/STAT3/Snail signal axis by interacting with SOCS1 to induce glycose metabolism disorders of cholangiocytes in gene knockout animal models and clinical samples.

IL-6/JAK/STAT3信号通路在胆道慢性炎症诱发胆管上皮细胞恶性转化中发挥重要作用，然而其调控机理尚未明确。本项目预实验发现，IL-6长时间刺激胆管上皮细胞可通过激活JAK/STAT3信号通路介导视黄酸受体γ（RARγ）高表达，且RARγ可与SOCS1结合，促进STAT3再活化；过表达RARγ赋予IL-6持续激活JAK/STAT3信号通路并诱发胆管上皮细胞糖代谢紊乱。因此，本项目拟进一步研究RARγ与SOCS1相互作用如何促进SOCS1泛素化蛋白酶体降解及抑制SOCS1与JAK结合，进而解除SOCS1对JAK/STAT3信号通路的负调控作用，最终促使IL-6/STAT3/Snail信号轴持续激活而诱发胆管上皮细胞糖代谢发生紊乱；最后在基因敲除动物模型和临床样本整体进一步确证RARγ与SOCS1相互作用调控IL-6/STAT3/Snail信号轴诱发胆管上皮细胞糖代谢紊乱的机制。

胆道非可控性炎症是诱发胆管上皮细胞恶性转化的重要因素，其形成调控机制亟待阐明。原发性硬化性胆管炎、胆道感染、胆道结石以及胆道损伤、肥胖、脂肪肝等因素诱发胆道形成炎症微环境，促使胆管上皮细胞内信号通路调控网络发生紊乱，最终导致胆管上皮细胞恶性转化。视黄酸受体γ（retinoic acid receptor γ，RARγ）在胆管癌组织中异常高表达，其表达下调可明显抑制胆管癌细胞生长与成瘤、迁移与侵袭，以及提高胆管癌细胞药物敏感性。然而，RARγ异常高表达的原因及其调控胆管上皮细胞恶性转化的机制尚不清楚。因此，本项目在前期项目基础上，进一步研究RARγ调控胆管癌发生发展的作用机制及其异常高表达的分子机制。研究发现，TNFα、IL-6、IL-1β这三种炎症因子可显著诱导胆管癌细胞RARγ异常高表达，同时葡萄糖缺乏及缺氧微环境可促进胆管癌细胞RARγ的表达异常升高。为研究RARγ调控胆管癌发生发展的分子机制，我们运用蛋白组学分析发现，RARγ在胆管癌细胞糖代谢过程中起到重要的调控作用，并且可能与其调控靶基因AKR1C1表达相关。细胞模型进一步研究确证，RARγ通过调控AKR1C1表达参与了胆管癌细胞糖代谢重编程。AKR1C1在胆管癌临床样本中表达较高并且具有显著临床意义，RARγ与AKR1C1表达呈正相关。敲低AKR1C1不但抑制胆管癌有氧糖酵解，还抑制胆管癌细胞增殖及提高胆管癌细胞对5-FU的药敏性。进一步分子机制研究发现，RARγ通过与CREB相互作用，抑制CREB泛素化降解，从而激活CREB信号通路促进AKR1C1表达升高。因此，本项目研究阐明了胆管癌细胞逆环境诱导RARγ异常高表达，然后通过与CREB相互作用，抑制CREB泛素化降解，从而激活CREB信号通路促进AKR1C1表达升高，最终导致胆管癌细胞糖代谢紊乱。本项目研究结果进一步揭示了胆管癌发生发展的分子机理，可为RARγ作为临床胆管癌基因治疗靶点提供科学实验依据。