Prognostic value of miR-221-3p, miR-342-3p and miR-491-5p expression in colon cancer.

Increasing evidence has demonstrated that microRNAs (miRNAs) are involved in colon cancer initiation and progression, and may serve as diagnostic and prognostic biomarkers for colon cancer. Here, we investigated the levels of miR-9-1, miR-203-3p, miR-221-3p, miR-342-3p, miR-491-5p and miR-503-5p in 90 pairs of colon cancer and adjacent normal tissues, and explored the relationship between their expression and clinical outcome of colon cancer. Five miRNAs (miR-203-3p, miR-221-3p, miR-342-3p, miR-491-5p and miR-503-5p) were dysregulated in colon cancer tissue (P < 0.05). The levels of miR-503-5p in larger tumors (≥ 6 cm) were higher than those in smaller ones (< 6 cm) (P = 0.031), while the levels of miR-203-3p and miR-491-5p in patients aged 70 years and older were higher than those in patients aged younger than 70 years (P = 0.019 and 0.049, respectively). The high levels of miR-221-3p (HR = 2.416, 95% CI 1.314-4.445, P = 0.005), miR-342-3p (HR = 1.807, 95% CI 1.003-3.253, P = 0.049) and miR-491-5p (HR = 1.868, 95% CI 1.032-3.384, P = 0.039) were significantly associated with worse survival time. Moreover, combination analysis of miR-221-3p, miR-342-3p and miR-491-5p expression revealed that patients with 3 highly expressed miRNAs had lower survival rates compared with those with zero-to-two highly expressed miRNAs (HR = 2.100, 95% CI 1.157-3.813, P = 0.015), especially those with TNM stages I and II (HR = 4.204,95% CI 1.762-10.030, P = 0.001). Our results suggest that the three-miRNA signature may help doctors better predict prognosis and guide treatment decisions for colon cancer.