Tang Hao-Dong, Wang Yang, Xie Peng, Tan Si-Yuan, Li Hai-Feng, Shen Hao, Zhang Zheng, Lei Zheng-Qing, Zhou Jia-Hua
Department of Surgery, School of Medicine, Southeast University, Nanjing, China.
Department of Hepato-Pancreatico-Biliary Surgery, Zhongda Hospital Southeast University, Nanjing, China.
Front Genet. 2022 Jun 8;13:892177. doi: 10.3389/fgene.2022.892177. eCollection 2022.
Metastasis is the major cause of death in patients with pancreatic ductal adenocarcinoma (PDAC), and circulating tumor cells (CTCs) play an important role in the development of metastasis. However, few studies have uncovered the metastasis mechanism of PDAC based on CTCs. In this study, the existing bulk RNA-sequencing (bulk RNA-seq) and single-cell sequencing (scRNA-seq) data for CTCs in pancreatic cancer were obtained from the Gene Expression Omnibus (GEO) database. Analysis of tumor-infiltrating immune cells (TIICs) by CIBERSORT showed that the CTCs enriched from the peripheral blood of metastatic PDAC were found to contain a high proportion of T cell regulators (Tregs) and macrophages, while the proportion of dendritic cells (DCs) was lower than that enriched from localized PDAC. Through weighted gene co-expression network analysis (WGCNA) and the result of scRNA-seq, we identified the hub module (265 genes) and 87 marker genes, respectively, which were highly associated with metastasis. The results of functional enrichment analysis indicated that the two gene sets mentioned above are mainly involved in cell adhesion and cytoskeleton and epithelial-mesenchymal transition (EMT). Finally, we found that HMGB3 was the hub gene according to the Venn diagram. The expression of HMGB3 in PDAC was significantly higher than that in normal tissues (protein and mRNA levels). HMGB3 expression was significantly positively correlated with both EMT-related molecules and CTC cluster-related markers. Furthermore, it was also found that HMGB3 mutations were favorably related to tumor-associated immune cells through the TIMER2.0 online tool. We further demonstrated that PDAC patients with higher HMGB3 expression had significantly worse overall survival (OS) in multiple datasets. In summary, our study suggests that HMGB3 is a hub gene associated with EMT in CTCs, the formation of CTC clusters, and infiltration patterns of immune cells favorable for tumor progression and metastasis to distant organs.
转移是胰腺导管腺癌（PDAC）患者死亡的主要原因，循环肿瘤细胞（CTC）在转移的发生发展中起重要作用。然而，基于CTC揭示PDAC转移机制的研究较少。在本研究中，胰腺癌CTC的现有批量RNA测序（bulk RNA-seq）和单细胞测序（scRNA-seq）数据从基因表达综合数据库（GEO）中获取。通过CIBERSORT对肿瘤浸润免疫细胞（TIIC）进行分析，结果显示，从转移性PDAC外周血中富集的CTC含有高比例的T细胞调节因子（Tregs）和巨噬细胞，而树突状细胞（DCs）的比例低于从局限性PDAC中富集的CTC。通过加权基因共表达网络分析（WGCNA）和scRNA-seq结果，我们分别鉴定出了与转移高度相关的枢纽模块（265个基因）和87个标记基因。功能富集分析结果表明，上述两个基因集主要参与细胞黏附、细胞骨架和上皮-间质转化（EMT）。最后，根据维恩图我们发现HMGB3是枢纽基因。HMGB3在PDAC中的表达显著高于正常组织（蛋白质和mRNA水平）。HMGB3表达与EMT相关分子和CTC簇相关标志物均呈显著正相关。此外，通过TIMER2.0在线工具还发现HMGB3突变与肿瘤相关免疫细胞呈正相关。我们进一步证明，在多个数据集中，HMGB3表达较高的PDAC患者总生存期（OS）显著较差。总之，我们的研究表明，HMGB3是与CTCs中EMT、CTC簇形成以及有利于肿瘤进展和远处器官转移的免疫细胞浸润模式相关的枢纽基因。
