食管鳞癌中Polι诱导肿瘤相关巨噬细胞M2型极化介导肿瘤转移的机制研究

M2 polarization of macrophage in tumor microenvironment is an important cause of distant metastasis of esophageal squamous cell carcinoma (ESCC). A variety of factors have been known to influence the polarization of macrophage. Recently, we found that DNA polymerase iota (Polι) promotes ESCC metastasis and the exosomes derived from Polι over-expressed ESCC cells induce M2 polarization of macrophage. Thus, we speculate that Polι participates in regulating M2 polarization of macrophage in tumor microenvironment, which promotes ESCC cell metastasis, yet the mechanism remains unclear. To explore the mechanism, high-throughput sequencing method was used to analyze the microRNAs expression in exosomes derived from Polι over-expressed ESCC cells. The results revealed that microRNA-20a-5p was highly elevated. Further bioinformatics analysis predicted that microRNA-20a-5p could regulate STAT3 signaling pathway, which was critical for macrophage M2 polarization. In this project, we will further clarify the mechanism of Polι-mediated ESCC metastasis through inducing M2 polarization of macrophage via exosomes-packaged microRNA-20a-5p. This study is expected to illustrate the mechanism of Polι promoting ESCC metastasis from the tumor microenvironment perspective, and provide a potential target for ESCC therapy.

肿瘤微环境中巨噬细胞M2型极化是食管鳞癌（ESCC）远处转移的重要因素。影响巨噬细胞极化的因素很多，近来我们发现跨损伤DNA聚合酶Polι促进ESCC转移；Polι过表达的ESCC细胞外泌体可诱导巨噬细胞M2型极化。因此，我们推断Polι可能参与调控肿瘤微环境中巨噬细胞M2型极化，促进ESCC细胞转移，但机制不清。为探索其机制，我们采用高通量测序方法分析Polι过表达的ESCC细胞外泌体中microRNAs，结果显示microRNA-20a-5p异常高表达；生物信息学预测microRNA-20a-5p可参与调控巨噬细胞M2型极化关键通路STAT3。本项目拟从细胞、动物及临床样本水平进一步阐明Polι通过外泌体包裹microRNA-20a-5p诱导巨噬细胞M2型极化，促进ESCC细胞转移的机制。本研究有望从肿瘤微环境角度揭示Polι促进ESCC细胞转移的机制，为ESCC治疗提供潜在的靶点。

肿瘤微环境中巨噬细胞M2型极化是食管鳞癌(ESCC)远处转移的重要因素。Polι是跨损伤DNA合成途径的聚合酶，参与调控基因损伤修复和细胞的侵袭转移。我们的研究结果表明：在ESCC细胞中，Polι促进microRNA-1181和microRNA-3960的表达，过表达的microRNA-1181和microRNA-3960经ESCC细胞外泌体进入巨噬细胞，诱导其M2型极化。HIF-1a作为Polι的转录因子调控ESCC细胞中Polι的转录；高表达的Polι通过增强USP7与HIF-1a的结合，促进USP7对HIF-1a的去泛素化调节，从而上调细胞内HIF-1a蛋白的表达，形成HIF-1a-Polι-HIF-1a回路。此外，体内外实验表明Polι可以介导乏氧诱发的细胞转移。综上，ESCC细胞中高表达的Polι能够通过调控肿瘤微环境影响肿瘤细胞的进展，同时也可以逆转乏氧诱发的ESCC转移，提示Polι可能是治疗ESCC的重要靶点。