Transcriptome analysis in primary colorectal cancer tissues from patients with and without liver metastases using next‐generation sequencing

Colorectal cancer (CRC) is the third most common cancer worldwide and liver metastases are the leading cause of death in patients with CRC. In this study, we performed next‐generation sequencing profiling on primary colorectal tumor tissues obtained from three CRC patients with liver metastases and three CRC patients without liver metastases to identify differentially expressed genes (DEGs) that might be responsible for the metastases process. After filtering 2690 DEGs, comprising 996 upregulated and 1694 downregulated RNAs, 22 upregulated and 73 downregulated DEGs were identified. Gene ontology (GO) and pathway analyses were performed to determine the underlying mechanisms. Single‐organism process (biological process), cell (cellular component), and binding (molecular function) were the most related terms in the GO analysis. We selected the top 13 upregulated and top 12 downregulated genes by fold change to verify their differential expression using quantitative real‐time reverse transcription PCR (qRT‐PCR) and immunohistochemistry (IHC). The validation showed that three most significantly upregulated DEGs were HOXD10,UGT2A3, and SLC13A2, whereas the five most significantly downregulated DEGs were SPP1,CXCL8,MMP3,OSM, and CXCL6, respectively. These aberrantly expressed genes may play pivotal roles in promoting or inhibiting metastases. Further studies are required to determine the functions of DEGs to promote the diagnosis of metastases and provide novel chemotherapy targets.