microRNA-181a is associated with poor prognosis of colorectal cancer.

miRNAs regulate gene expression at the post-transcriptional level by degradation of mRNA and translational repression. Recent studies have shown that miR-181a is dysregulated in several types of cancer; however, the clinical significance of miR‑181a in colorectal cancer (CRC) remains unclear. We addressed this question by using quantitative real-time PCR (qRT-PCR) to analyze miR-181a expression in 162 CRC patients. There was no significant difference in miR-181a expression in normal colon vs. colorectal cancer tissue. The cancer tissue samples were categorized into a low and high expression group based on miR-181a expression. Comparison of the clinicopathological factors and prognosis in these two groups showed that the high expression group had a significantly poorer prognosis than the low expression group (P=0.011). Multivariate analysis indicated that high miR-181a expression was an independent significant prognostic factor for CRC. However, there no correlation was observed between miR-181a expression and clinicopathological parameters. In vitro analysis revealed that the overexpression of miR-181a repressed the expression of the tumor suppressor, phosphatase and tensin homolog (PTEN) located on chromosome 10, at the mRNA level. These data suggest that miR-181a may be a new independent prognostic factor for CRC patients.