Chang Hulin, Jin Lei, Xie Peiyi, Zhang Bo, Yu Mincheng, Li Hui, Liu Shuang, Yan Jiuliang, Zhou Binghai, Li Xiaoqiang, Xu Yongfeng, Xiao Yongsheng, Ye Qinghai, Guo Lei
Department of Hepatobiliary Surgery, Shaanxi Provincial People's Hospital, Xi'an, China.
Department of Liver Surgery and Transplantation, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai, China.
J Gastrointest Oncol. 2022 Oct;13(5):2351-2365. doi: 10.21037/jgo-22-829.
Colorectal cancer (CRC) is one of the most prominent malignant diseases, with a high incidence and a dismal prognosis. Metastasis to the liver is the leading cause of death in CRC patients. This study aimed to identify accurate metastatic biomarkers of CRC and investigate the potential molecular mechanisms of liver metastasis of colorectal cancer (LMCRC).
Three independent datasets were screened and downloaded from the Gene Expression Omnibus (GEO) database. The GEO2R tool was used to identify differentially expressed genes (DEGs) in CRC tissues and liver metastases. Next, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted using the Database for Annotation, Visualization, and Integrated Discovery (DAVID). Furthermore, the protein-protein interactions (PPIs) of the DEGs were analyzed using the Search Tool for the Retrieval of Interacting Genes (STRING) database, Cytoscape, and Molecular Complex Detection (MCODE). Next, the expression levels and Kaplan-Meier survival analysis of the target gene between normal colon and CRC tissues were performed by UALCAN. The expression of the target gene in tissues and cell lines was verified by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blot, and immunohistochemistry (IHC) assay. The impact of the target gene on the proliferation, invasion, and migration ability of COAD cells was explored .
A total of 92 common DEGs were found in the three independent datasets. GO/KEGG enrichment analysis showed that the DEGs were mainly involved in 14 different pathways. The protein-protein interaction (PPI) network revealed that complement 5 (C5), the upstream gene of C8A in the complement system, was associated with C8 and other key hub genes. Meanwhile, the online UALCAN resource showed that C5 was up-regulated and facilitated malignant progression in COAD samples. Next, we confirmed that C5 remarkably increased and promoted cell proliferation, migration, and invasion in CRC cell lines, SW620 and SW480. The IHC assay showed C5 was also highly expressed in a majority of LMCRC tissues compared with paired CRC tissues.
The findings of our integrated bioinformatics study suggest that complement C5 might serve as a potential therapeutic target in patients with CRC.
结直肠癌（CRC）是最常见的恶性疾病之一，发病率高且预后不佳。肝转移是CRC患者的主要死因。本研究旨在确定CRC准确的转移生物标志物，并探讨结直肠癌肝转移（LMCRC）的潜在分子机制。
从基因表达综合数据库（GEO）筛选并下载三个独立数据集。使用GEO2R工具鉴定CRC组织和肝转移灶中的差异表达基因（DEG）。接下来，使用注释、可视化和综合发现数据库（DAVID）进行基因本体论（GO）和京都基因与基因组百科全书（KEGG）富集分析。此外，使用相互作用基因检索工具（STRING）数据库、Cytoscape和分子复合物检测（MCODE）分析DEG的蛋白质-蛋白质相互作用（PPI）。接下来，通过UALCAN对正常结肠组织和CRC组织之间的靶基因表达水平进行分析及Kaplan-Meier生存分析。通过定量逆转录-聚合酶链反应（qRT-PCR）、蛋白质印迹和免疫组织化学（IHC）检测验证靶基因在组织和细胞系中的表达。探讨靶基因对COAD细胞增殖、侵袭和迁移能力的影响。
在三个独立数据集中共发现92个常见的DEG。GO/KEGG富集分析表明，DEG主要参与14条不同的信号通路。蛋白质-蛋白质相互作用（PPI）网络显示，补体系统中C8A的上游基因补体5（C5）与C8及其他关键枢纽基因相关。同时，在线UALCAN资源显示C5在COAD样本中上调并促进恶性进展。接下来，我们证实C5在CRC细胞系SW620和SW480中显著增加并促进细胞增殖、迁移和侵袭。IHC检测显示，与配对的CRC组织相比，C5在大多数LMCRC组织中也高表达。
我们综合生物信息学研究的结果表明，补体C5可能是CRC患者的潜在治疗靶点。
