Prognostic value of miRNA-181a in human colorectal cancer evaluated by in situ hybridization

Background: Colorectal cancer (CRC) is one of the most common cancers in the world and the 5th leading cause of cancer death in China. CRC affects the gastrointestinal tract and has a high mortality rate. Recent studies have demonstrated the abnormal expression of miRNA-181a in a wide variety of tumors. However, the clinical significance of miRNA-181a in CRC is still unclear. Methods: The detection of miRNA-181a was performed by probe hybridization using 3' and 5' end LNA-modified DNA probes. And we evaluated the survival probabilities by the Kaplan-Meier method and the logrank test. Furthermore, the univariate and multivariate Cox proportional hazard regression model were used for assessing the association of the miRNA-181a expression and prognosis. Results: MiRNA-181a was highly expressed in CRC (P<0.01) compared with tumor-adjacent control tissue and was further validated using The Cancer Genome Atlas (TCGA) database. Tumor size, clinical stage, peritoneal and liver metastasis were significantly associated with high expression of miRNA-181a (P<0.001, P=0.003, P=0.018 and P=0.004). We also found that high expression of miRNA-181a was associated with poor prognosis (P<0.001). Furthermore, CRC patients with low expression of miRNA-181a were more benefit for adjuvant chemotherapy (P<0.01). In addition, Cox multiple regression analysis suggested that miRNA-181a was an independent prognostic factor for CRC. Conclusions: These results indicated that expression levels of miRNA-181a could be an important indicator for prognosis and survival for CRC patients.