The expression profile of RNA sensors in colorectal cancer and its correlation with cancer stages

BACKGROUND: RNA sensors represent the most important pattern recognition receptors (PRRs) to defend against RNA pathogens, such as RNA viruses. Recent studies revealed their critical roles in inflammatory and autoimmune diseases. Furthermore, more recent evidences indicated that RNA sensors mediate the development of colitis or colorectal cancer (CRC). However, a systematic understanding of RNA sensors in CRC is still lacking, especially the expression patterns in CRC. METHODS: Here, we analyzed RNA sensor expression, clinical significance, and possible mechanisms in CRC by combining bioinformatic analysis and the analysis on pre-cancerous animal model and clinical tissue samples. RESULTS: We found that most of the members of RNA sensors, including RNA-sensing Toll-like receptors (TLR3, TLR7, and TLR8) and RIG-I-like receptors (MDA5 and RIG-I), were down-regulated in CRC, while the expression of DDX21 were up-regulated in human CRC. In addition, we also analyzed the correlation between gene expression and cancer stages. We found that the expression of RNA-sensing TLRs, RIG-I, and DDX21 in CRC were associated with cancer stages. Finally, in order to explore the possible mechanisms, the correlation between RNA sensors and the main downstream signaling molecules were analyzed. A positive correlation was observed in TLR7/8 and MyD88, RIG-I/MDA5 and LGP2, while a negative correlation was observed in RIG-I/MDA5 and MAVS. CONCLUSIONS: This study reveals the potential values of RNA-sensing genes including TLRs, RIG-I and DDX21 as biomarkers of CRC formation, progression and therapy.