Abstract: Objective This research focuses on identifying a subset of macrophages that specifically and highly express the GGT5 gene. To date, there have been no reports on the GGT5+ macrophage subset. Our objective is to elucidate the role of GGT5+ macrophages in the progression of ESCC and the mechanisms regulating their expression. Methods Using TCGA, we conducted differential gene expression analysis to identify key genetic changes. Subsequently, with the aid of the TIMER database, we conducted an in-depth analysis of the relationship between GGT5 expression levels and immune cell infiltration, with a particular focus on macrophages.To further validate these analytical results, we employed immunohistochemical and immunofluorescence techniques to visually confirm the expression of GGT5 at the sample level. Finally, through Western blotting experiments, we conducted thorough exploration and validation of the regulatory mechanisms of GGT5. Results Bioinformatics analysis revealed that GGT5 exhibits significantly high expression characteristics in ESCA, and its expression level was closely related to the activity of macrophages. Immunohistochemical and immunofluorescence experiments showed that GGT5 was specifically highly expressed mainly in M2-macrophages and its expression was also significantly increased in LNM. In the study of regulatory mechanisms, it was found that CAFs significantly regulate the expression of GGT5 in macrophages by secreting the IGF-1 cytokine, leading to a marked upregulation of GGT5 expression levels. Conclusion The results indicate that CAFs in the TME regulate the expression of GGT5 in macrophages by secreting the IGF-1 cytokine, thereby participating in the initiation and progression of ESCC. This discovery provides important insights for understanding the pathogenesis of ESCC and exploring new therapeutic strategies.

Key words: ESCC, Gamma-Glutamyltransferase 5, macrophages, fibroblast

摘要： 目的 本研究聚焦于探索一种巨噬细胞亚群,该亚群特异性地高表达GGT5基因,而目前尚无关于GGT5+巨噬细胞亚群的报道。本研究旨在明确GGT5+巨噬细胞在食管鳞状细胞癌进展中的作用及其表达调控机制。方法 利用TCGA中的食管癌数据进行差异基因分析。借助TIMER数据库深入分析GGT5的表达量与免疫细胞浸润之间的关系,特别是巨噬细胞。为了进一步验证这些分析结果,采用免疫组化和免疫荧光等技术,在样本层面对GGT5的表达情况进行直观的确认。最后,通过Western blotting实验对GGT5的调控机制进行深入的探究和验证。结果 生物信息学分析显示,GGT5在食管癌中呈显著高表达,且其表达水平与巨噬细胞的活跃度紧密相关。通过免疫组化和免疫荧光实验,显示GGT5主要在M2型巨噬细胞中特异性高表达,并且在小鼠肿瘤转移的腘窝淋巴结中的表达量也显著上升。调控机制研究中发现,食管鳞癌周围的肿瘤相关成纤维细胞（CAFs）通过分泌IGF-1细胞因子,对巨噬细胞内GGT5的表达产生了显著的调控作用,导致GGT5表达水平显著上调。结论 肿瘤微环境中的肿瘤相关成纤维细胞通过分泌IGF-1细胞因子,调控巨噬细胞GGT5的表达,从而参与食管鳞癌的发生和发展过程。这一发现为理解食管鳞癌的发病机制和探索新的治疗策略提供了重要的线索。

关键词: 食管鳞癌, GGT5, 巨噬细胞, 成纤维细胞