肿瘤相关巨噬细胞NLRP3异常激活介导膀胱癌耐药的机制

Tumor-associated macrophages (TAMs) are thought to play essential roles in promoting cancer chemoresistance and recurrence. However, how TAMs regulate cancer cells remains unclear. Recent research indicated that NLRP3 can regulate the inflammatory response of TAMs and affect the biological behavior of tumor, but it is still unknown in bladder cancer. We found that the activation of NLRP3 in TAMs mediates the stemness and chemoresistance of bladder cancer cells, and the secretion of IL-34 mediated by NLRP3 is a key molecule in promoting chemoresistance of bladder cancer cells. Moreover, we found that IL-34 was regulated by the non-canonical NLRP3/Caspase-8 pathway, rather than by the canonical NLRP3/Caspase-1 pathway and was related to the activation of NF-κB. Hence, we propose the hypothesis that the activation of non-canonical NLRP3/Caspase-8/NF-κB/IL-34 pathway in TAMs promote stemness maintenance and chemorsistance of bladder cancer. At first, we plan to testify the stemness promoting and chemoresistance function of paracrine IL-34 mediated by NLRP3 from TAMs in vitro and in vivo. Furthermore, we will test the mechanism and signalling pathway of IL-34 mediated by NLRP3 activation. At last, we will explore the clinical significance of NLRP3 and IL-34 in human bladder cancer. Taken together, this research will not only reveal the mechanism of drug resistance in bladder cancer, but also provide a new target for treatment.

肿瘤相关巨噬细胞与肿瘤耐药、复发密切相关。最新研究发现NLRP3可调控肿瘤相关巨噬细胞介导的炎症反应，影响肿瘤生物学行为，而膀胱癌领域尚为空白。我们前期研究发现肿瘤相关巨噬细胞NLRP3介导的IL-34分泌是促进膀胱癌干性维持和化疗耐药的关键分子，并发现IL-34受NLRP3/Caspase-8非经典通路调控，而非NLRP3/Caspase-1经典通路，且与NF-κB活化有关。因此，我们提出NLRP3介导非经典ASC/Caspase-8/NF-κB/IL-34途径激活，促进膀胱癌干性维持和化疗耐药的假说。本项目拟先体外和体内确定肿瘤相关巨噬细胞NLRP3激活介导IL-34分泌，促进膀胱癌化疗耐药的作用；然后，探究NLRP3异常激活介导IL-34产生的分子机制；最后，验证临床膀胱癌组织IL-34、NLRP3表达的临床意义。本项目不仅能进一步揭示膀胱癌耐药的发生机制，而且能为治疗提供新靶点。

膀胱尿路上皮癌（UC）是泌尿系统最常见的恶性肿瘤之一，其发病率和死亡率逐年上升。浸润性膀胱尿路上皮癌易进展和转移，预后差，五年生存率低。炎症在膀胱尿路上皮癌的发生和发展中具有重要的作用，研究发现肿瘤微环境中TAMs和膀胱癌细胞均分泌IL-34促进膀胱癌细胞进展和化疗耐药，并主要由炎症小体NLRP3介导，因此NLRP3和IL-34是有望改善膀胱癌化疗耐药的重要分子。肿瘤免疫微环境在肿瘤的发生和发展中发挥极为重要的作用。为了进一步深入研究肿瘤免疫微环境的状态，本研究收集12例尿路上皮癌根治术患者的UC组织和14例癌旁正常组织，应用单细胞质谱流式技术，试图获得更全面、详细的肿瘤免疫学图谱，为潜在的预后标志物和免疫治疗靶点提供信息。研究发现，T细胞为UC中的主要免疫细胞群，占比最高，其次还有B细胞、巨噬细胞等。尿路上皮癌中浸润的免疫细胞比例减少，说明它是一个免疫反应不强的“冷肿瘤”。Treg细胞在UC中相对富集，这可能介导了肿瘤的免疫逃逸。本研究共鉴定了71个T细胞表型，30个TAMs表型，并分析了两者之间的相关性。研究发现，CD38在TAMs中的表达明显高于PD-L1，CD38+TAMs与免疫抑制密切相关。因此，CD38可能是一个比PD1/PD-L1更适合UC的免疫治疗靶点。