Background
Colon cancer is the third leading cause of death in the world. According to the etiology, colon cancer can be divided into three categories: sporadic, hereditary, and colitis-associated colon cancer(CAC). In terms of clinical features, CAC patients have younger age of onset, more multiple lesions, more difficult to find under endoscope, stronger tumor invasiveness than sporadic colorectal cancer patients. Early detection of CAC by endoscopic monitoring is a challenge, and the incidence of septal colorectal cancer is still high. So it is indispensable to find the biomarkers to predict tumorigenesis of CAC.
Methods
The gene expression profiles of GSE43338 and GSE4904 were downloaded from Gene Expression Omnibus (GEO) database. The Limma package was used to standardize the data and obtain differentially expressed genes (DEGs). Protein-protein interaction (PPI) network was evaluated by STRING database. The Cytoscape software was used to establish PPI network and to perform modular analysis. Functional annotation analysis were performed by the DAVID. The transcription factor (TF) and miRNAs that regulate genes expression were analyzed by using the Network Analyst algorithm. Expression correlation analysis were conducted in GEPIA. The prognostic analysis of hub genes were conducted based on TCGA samples.
Results
A total of 275 DEGs including 103 up-regulated genes and 172 down-regulated genes were identified by bioinformatics analysis in CAC. IGF1, BMP4, SPP1, APOB, CCND1, CD44, PTGS2, CFTR, BMP2, KLF4, TLR2 were identified as hub DEGs, which were significantly enriched in PI3K-Akt signaling pathway, stem cell pluripotency regulation pathway, Focal adhesion-Hippo signal pathway and AMPK signal pathway respectively. The FOXC1 were crucial regulators for these hub gene according to the TF analysis. The Sankey diagram showed that both PI3K-AKT signal pathway and Focal adhesion were composed of up-regulated genes, such as SPP1, CD44, TLR2, CCND1, IGF1, which were related to core miRNAs, hsa-mir-16-5p, hsa-mir-129-2-3p and hsa-mir-37a-3p by research and prediction. Survival analysis showed that the differential expression of SPP1, CFRT and KLF4 was significantly related to the poor prognosis of CAC.
Conclusion
This study provided a novel way to illuminate the mechanism of colitis-associated colon cancer. The most of all, the hub genes and signaling pathways may contribute to the prevention, diagnosis and treatment of CAC.