MicroRNA-206 overexpression is associated with a prominent inflammatory reaction and a favorable colorectal cancer prognosis

Background: MicroRNAs act as oncogenes or tumor suppressors in various cancers. The tumor microenvironment (TME) plays an important role in tumor cell progression and survival. Methods: MicroRNA expressions were evaluated by using NanoString nCounter assay, qRT-PCR and in situ hybridization. Correlation between MircoRNA expressions and TME factors, clinicopathological behaviors and prognostic significance were assessed in 323 surgically resected colorectal cancers. Results: The microRNA-206 expression was identified significantly higher in Glasgow microenvironment score (GMS) 0 than in GMS 1 or GMS 2 by using the NanoString nCounter assay and qRT-PCR. High microRNA-206 expression was identified in 155 (48.0 %) cases in in situ hybridization and was significantly correlated with low pT classification, and absence of lymphovascular and perineural invasion, and lymph node metastasis. MicroRNA-206 expression was significantly associated with low tumor stroma percentage (TSP), high Klintrup-Makinen (KM) grade and low GMS. Patients with high microRNA-206 expression showed significantly better 5-year overall survival than those with low microRNA-206 expression, and was an independent prognostic factor in patients with colorectal cancer. High miR-206 expression was associated with TME, favorable clinicopathologic behaviors and overall survival and presents an independent prognostic factor in patients with colorectal cancer. Conclusion: Thus, MicroRNA-206 expression presents a feasible prognostic factor and potential therapeutic target to treat patients with colorectal cancer.