趋化因子CXCL13在肺癌发生发展中的作用

More than 90% of lung cancers are caused by cigarette smoke and air pollution, with polycyclic aromatic hydrocarbons (PAHs) as key carcinogens. In a previous work we showed that a chemokine CXCL13 was overexpressed in 63/70 (90%) of air pollution-related lung cancer and 44/71 (62%) of smoker lung cancers from control regions. The CXCL13 expression level was inversely associated with the prognosis of patients. The key carcinogen benzo(a)pyrene (BaP) induced CXCL13 production in lung epithelial cells and in mice prior to development of detectable lung cancer. Deficiency in Cxcl13 or its receptor, Cxcr5, significantly attenuated BaP-induced lung cancer in mice, demonstrating CXCL13’s critical role in PAH-induced lung carcinogenesis. In this project, we will establish Cxcl13 transgenic mouse and investigate whether the overexpression of Cxcl13 will cause lung cancer in vivo. Tandem Mass Tag (TMT) quantitative proteomic technology will be employed to dissect the differentially expressed proteins in lung tissues of wild type and Cxcl13-transgenic mice, and in wild type or Cxcl13-/- mice treated with BaP. We will develop the anti-CXCL13 antibody and test its anti-lung cancer efficacy in the patient-derived xenograft mouse models. Through this project we will elucidate the mechanisms of CXCL13 in promoting lung cancer, and provide novel therapeutics to tame lung cancer.

90%的肺癌是由吸烟与空气污染所诱发。近来我们发现趋化因子CXCL13在吸烟和空气污染相关肺癌中显著高表达，其表达越高患者预后越差；多环芳烃类致癌物的代表苯并芘（BaP）可促使肺上皮细胞分泌CXCL13并使小鼠发生肺癌，但敲除CXCL13可显著抑制BaP引起的肺癌，说明CXCL13在肺癌发生中起关键作用（eLife 2015）。本项目拟构建CXCL13转基因小鼠，研究其过表达能否引发肺癌；用标记定量蛋白质组技术（TMT）分析CXCL13转基因小鼠与对照鼠肺组织差异表达的蛋白质；用BaP处理CXCL13敲除鼠与野生型小鼠，取其肺组织进行TMT分析，揭示敲除CXCL13后抑制肺癌发生的蛋白质；制备CXCL13中和抗体、构建病人来源肺癌PDX模型检测CXCL13抗体的疗效，并用蛋白质芯片检测抗体治疗引起哪些蛋白质的变化。本项目的实施可阐明CXCL13引发肺癌的机理并为肺癌治疗提供新选择。

前期研究表明CXCL13在空气污染地区的肺癌病人组织中高表达，且CXCL13敲除或其受体CXCR5敲除的小鼠模型能显著抑制致癌物BaP引起的肺癌。基于前期的研究结果，CXCL13-CXCR5信号轴在肺癌的发生发展中具有重要作用，但对于CXCL13是否能诱发肺癌的发生发展及其是否能作为肺癌的治疗靶点，尚未有明确的认识。本项目通过构建肺部高表达CXCL13的模型鼠探究CXCL13的具体作用；制备单克隆抗体通过PDX模型评价其治疗效果；利用磷酸化蛋白芯片数据分析CXCL13促进肺癌发生发展的作用机制。在CXCL13慢病毒侵染的A/J鼠模型中及转基因小鼠中，CXCL13高表达小鼠发生肿瘤的数量明显高于对照组小鼠，且肿瘤体积也明显增大，说明CXCL13促进小鼠肺癌的发生发展。进一步利用单细胞转录组分析发现，CXCL13高表达小鼠肿瘤组织中存在特异性的一群抑制性T细胞，但对于这群细胞的特征和功能还需要进一步的探究。CXCL13单克隆抗体在治疗小鼠PDX模型中显示出明显的抑制肿瘤生长，降低肿瘤恶性程度的治疗效果。对CXCL13促进肺癌进程的机制进行探究，本研究发现，CXCL13可激活FAK；在肺癌细胞收到能量应激时，CXCL13高表达的细胞可通过CaMKKβ-AMPK通路诱导肺癌细胞抵抗能量应激诱导的细胞死亡，从而促进肿瘤的发展。由此，本项目发现CXCL13可招募特异的免疫抑制性细胞以及通过抵抗能量应激诱导的死亡来促进肺癌的发生发展，且CXCL13单克隆抗体具有抑制肿瘤生长的治疗效果，这些结果提示CXCL13可作为治疗肺癌的新靶点，为目前肺癌临床治疗提供策略。