Liu Yuan-Jie, Han Mei, Li Jie-Pin, Zeng Shu-Hong, Ye Qian-Wen, Yin Zhong-Hua, Liu Shen-Lin, Zou Xi
Department of Oncology, Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing, People's Republic of China.
No. 1 Clinical Medical College, Nanjing University of Chinese Medicine, Nanjing, People's Republic of China.
J Inflamm Res. 2022 Apr 15;15:2461-2476. doi: 10.2147/JIR.S361362. eCollection 2022.
Gap junctions, as one of the major ways to maintain social connections between cells, are now considered as one of the potential regulators of tumor metastasis. However, to date, studies on the relationship between gap junctions and colorectal cancer (CRC) are limited.
We synthesized connexins-coding gene expression data from public Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. Bioinformatics analysis was performed using R software and several database resources such as MEXPRESS database, Gene Set Cancer Analysis (GSCA) database, Human Protein Atlas (HPA) database, Tumor Immune Single Cell Hub (TISCH) database, Search Tool for Retrieval of Gene Interaction Relationships (STRING), and Cytoscape software, etc., to investigate the biological mechanisms that may be involved in connexins. Immunofluorescence and immunohistochemical staining were used to validate the expression and localization of GJA4.
We found that CRC patients can be divided into two connexin clusters and that patients in cluster C1 had shorter survival than in cluster C2. The infiltration of M1 macrophages and NK cells was lower in cluster C1, while the levels of M2 macrophages and immune checkpoints were higher, indicating an immunosuppressed state in cluster C1. In addition, the epithelial-mesenchymal transition (EMT) phenotype was significantly activated in cluster C1. We observed that GJA4 was up-regulated in colorectal cancer tissues, which was related to poor prognosis. It was mainly expressed in fibroblasts, but the expression levels in normal intestinal epithelial cells were low. Finally, we found that GJA4 was associated with M2 macrophages and may be a potential immunosuppressive factor.
We found that there is a significant correlation between abnormal connexins expression and patients' prognosis, and connexins play an important role in stromal-tumor interactions. Connexins, especially GJA4, can help enhance our understanding of tumor microenvironment (TME) and may guide more effective immunotherapeutic strategies.
间隙连接作为维持细胞间社交联系的主要方式之一，目前被认为是肿瘤转移的潜在调节因子之一。然而，迄今为止，关于间隙连接与结直肠癌（CRC）之间关系的研究有限。
我们从公共基因表达综合数据库（GEO）和癌症基因组图谱（TCGA）数据库中合成了连接蛋白编码基因表达数据。使用R软件以及多个数据库资源，如MEXPRESS数据库、基因集癌症分析（GSCA）数据库、人类蛋白质图谱（HPA）数据库、肿瘤免疫单细胞中心（TISCH）数据库、基因相互作用关系检索搜索工具（STRING）和Cytoscape软件等进行生物信息学分析，以研究可能与连接蛋白有关的生物学机制。采用免疫荧光和免疫组织化学染色来验证GJA4的表达和定位。
我们发现CRC患者可分为两个连接蛋白簇，C1簇患者的生存期比C2簇患者短。C1簇中M1巨噬细胞和NK细胞的浸润较低，而M2巨噬细胞和免疫检查点的水平较高，表明C1簇处于免疫抑制状态。此外，C1簇中的上皮-间质转化（EMT）表型被显著激活。我们观察到GJA4在结直肠癌组织中上调，这与预后不良有关。它主要在成纤维细胞中表达，但在正常肠上皮细胞中的表达水平较低。最后，我们发现GJA4与M2巨噬细胞相关，可能是一种潜在的免疫抑制因子。
我们发现连接蛋白表达异常与患者预后之间存在显著相关性，并且连接蛋白在基质-肿瘤相互作用中起重要作用。连接蛋白，尤其是GJA4，有助于增强我们对肿瘤微环境（TME）的理解，并可能指导更有效的免疫治疗策略。
