Background: The poor clinical prognosis of Stage IIIB colon cancer patients is due in part to the current lack of an effective diagnostic method being available and highlights a need for the identification of novel biomarkers like microRNA (miRNA).
Patients and methods: We used microarray analysis to compare the miRNA expression profiles of eight Stage IIIB colon cancer patients with worse clinical outcome (those who developed liver metastases between 8 and 18 months after surgery) against eight 'cured' Stage IIIB colon cancer patients (those who remained disease free following surgery during the same monitoring period). In addition, quantitative real-time polymerase chain reaction (qRT-PCR) analysis was performed examining miRNAs in tumor tissue of 98 patients with Stage IIIB colon cancer.
Results: We found, miRNA-192-3p and miRNA-192-5p were down regulated in the patients with worsening disease compared to the control 'cured' Stage IIIB colon cancer patients (P = 0.026 and P = 0.042, respectively). Patients with higher expression of miRNA-192-5p had higher 5-year disease-free survival (DFS) (84.21%) and overall survival (OS) (89.47%) than those with lower targeted miRNA expression DFS (38.8%; hazard ratio (HR): 3.74, 95% confidence interval (CI): 1.52-9.23, P = 0.042) and OS (48.57%; HR: 5.01, 95% CI: 1.75-14.38, P = 0.033). In contrast, patients with higher expression of miRNA-192-3p did not appear to statistically impact the survival of patients in this setting (DFS 73.33% vs 64.7%, HR: 0.68, 95% CI: 0.31-1.52, P = 0.35; OS 76.67% vs 66.17%, HR: 0.62, 95% CI: 0.27-1.45, P = 0.27).
Conclusions: The decreased expression of miRNA-192-5p found for patients with relapsing disease might represent a highly predictive marker to use for the prognosis of Stage IIIB colon cancer patients.