Radiographically, ground-glass nodules (GGN) and part-solid nodules (PSN) in lung adenocarcinoma (LUAD) have significant heterogeneity in their clinical manifestations, biological characteristics, and prognosis. This study aimed to explore the heterogeneity of LUAD in different radiological phenotypes and associated factors influencing tumor evolution. We performed single-cell RNA sequencing (scRNA-seq) on tumor tissues from eight and seven cases of GGN– and PSN–LUAD, respectively, at different disease stages, including minimally invasive adenocarcinoma (MIA), invasive adenocarcinoma (IAC), and metastatic lung cancer (MLC). Additionally, we analyzed adjacent normal tissues from four cases. Immunohistochemistry, multiplex immunofluorescence, and external scRNA-seq data were employed to confirm the expression of signature genes as well as the distribution patterns of CXCL9 + TAMs and TREM2 + TAMs. A LUAD mouse model was generated using gene editing, organoid culture, and orthotopic transplantation techniques, and comprehensive analyses such as histopathology, RNA sequencing, and Western blotting were performed to validate key pathways. Diverse cellular compositions were observed in the tumor microenvironment (TME) during GGN– and PSN–LUAD invasion and metastasis. Notably, CXCL9 + and TREM2 + tumor-associated macrophages (TAMs) exhibited the most significant enrichment changes. It was found that GGN–LUAD exhibited a stronger immune response than PSN–LUAD, with increased interaction between CXCL9 + TAMs and CD8 + tissue-resident memory T cells during invasion stage (MIA–IAC). Conversely, greater interactions between TREM2 + TAMs and tumor cells were observed in PSN–LUAD during the MLC stage. Additionally, TREM2 + TAMs were found to differentiate into TREM2 + /SPP1 + and TREM2 + /SPP1– TAMs at different stages, which promotes tumor progression. This study also emphasizes that during the transdifferentiation process of GGN– and PSN–LUAD, IFN-γ activates the STAT1 signaling pathway to regulate the activation of CXCL9 + TAMs, and further recruiting CD8 + Trm cells and activating T cells through MHC class I antigen presentation. The role of the IFN-γ/STAT1 pathway in the occurrence and development of LUAD was further validated by animal experiments. Our findings offer a potential therapeutic strategy to maintain a dynamic balance within the TME and improve the immunotherapy efficacy by modulating the relative proportions and functional states of CXCL9 + TAMs and TREM2 + TAMs.

中文翻译：

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单细胞 RNA 测序揭示了肺腺癌磨玻璃结节和部分实性结节的侵袭和转移过程中免疫微环境生态位转变


放射学检查显示，肺腺癌 （LUAD） 中的磨玻璃结节 （GGN） 和部分实性结节 （PSN） 在临床表现、生物学特征和预后方面具有显著的异质性。本研究旨在探讨 LUAD 在不同放射学表型中的异质性以及影响肿瘤演变的相关因素。我们对 8 例和 7 例 GGN 和 PSN-LUAD 的肿瘤组织进行了单细胞 RNA 测序 （scRNA-seq），分别处于不同疾病阶段，包括微浸润性腺癌 （MIA） 、浸润性腺癌 （IAC） 和转移性肺癌 （MLC）。此外，我们分析了 4 例的邻近正常组织。采用免疫组化、多重免疫荧光和外部 scRNA-seq 数据确认特征基因的表达以及 CXCL9 + TAMs 和 TREM2 + TAMs 的分布模式。使用基因编辑、类器官培养和原位移植技术生成 LUAD 小鼠模型，并进行组织病理学、RNA 测序和 Western blotting 等综合分析以验证关键通路。在 GGN – 和 PSN-LUAD 侵袭和转移过程中，在肿瘤微环境 （TME） 中观察到不同的细胞组成。值得注意的是，CXCL9 + 和 TREM2 + 肿瘤相关巨噬细胞 （TAM） 表现出最显着的富集变化。研究发现，GGN-LUAD 表现出比 PSN-LUAD 更强的免疫反应，在侵袭期 （MIA-IAC） CXCL9 + TAMs 和 CD8 + 组织驻留记忆 T 细胞之间的相互作用增加。相反，在 MLC 阶段，在 PSN-LUAD 中观察到 TREM2 + TAMs 与肿瘤细胞之间的相互作用更大。 此外，发现 TREM2 + TAMs 在不同阶段分化为 TREM2 + /SPP1 + 和 TREM2 + /SPP1– TAM，从而促进肿瘤进展。本研究还强调，在 GGN-和 PSN-LUAD 的转分化过程中，IFN-γ激活 STAT1 信号通路，调节 CXCL9 + TAMs 的激活，并通过 MHC I 类抗原呈递进一步募集 CD8 + Trm 细胞和激活 T 细胞。动物实验进一步验证了 IFN-γ/STAT1 通路在 LUAD 发生和发展中的作用。我们的研究结果提供了一种潜在的治疗策略，通过调节 CXCL9 + TAMs 和 TREM2 + TAMs 的相对比例和功能状态来维持 TME 内的动态平衡并提高免疫治疗效果。