Background: Lymph node metastasis is a major cause of cancer-related death in patients with colorectal cancer (CRC), but current strategies are limited to predicting this clinical behavior. Our study aims to establish a lymph node metastasis prediction model based on miRNA and mRNA to improve the accuracy of prediction.
Methods: GSE56350, GSE70574, and GSE95109 were downloaded from the Gene Expression Omnibus (GEO) database and 569 colorectal cancer statistics were also downloaded from The Cancer Genome Atlas (TCGA) database. Differentially expressed miRNAs were calculated by using R software. Besides, gene ontology and enriched pathway analysis of target mRNAs were analyzed by using FunRich. Furthermore, the mRNA–miRNA network was constructed using Cytoscape software. Gene expression level was also detected by performing qRT-PCR (quantitative real-time PCR) in colorectal cancer and lymph node tissues.
Results: In total, 5 differentially expressed miRNAs were selected, and 34 mRNAs were identified after filtering. The research of KEGG indicated that mRNAs are enriched in many cancer pathways. Differentially expressed miRNAs were most enriched in the cytoplasm, nucleoside, transcription factor activity, and RNA binding. KEGG pathway analysis of these target genes was mainly enriched in 5 pathways including fatty acid elongation, MAPK signaling pathway, autophagy, signaling pathways regulating pluripotency of stem cells, and Th17 cell differentiation. The results of qRT-PCR indicated that hsa-miR-100 and hsa-miR-99a were differentially expressed in lymph node metastatic colorectal cancer tissues and lymph node non-metastasis tissues which all target HS3ST2. Besides, we also found they have a significant difference in colorectal cancer tissues compared with normal tissues.
Conclusion: By using microarray and bioinformatics analyses, differentially expressed miRNAs were identified and a complete gene network was constructed. To our knowledge, HS3ST2 and related molecules including hsa-miR-100 and hsa-miR-99a were firstly identified as potential biomarkers in the development of lymph node metastatic colorectal cancer.
Keywords: microRNA, colorectal cancer, lymph node metastasis, prognostic signature