The ratio of miR-21/miR-24 as a promising diagnostic and poor prognosis biomarker in colorectal cancer

OBJECTIVE: Optimal management of cancer treatment will be guided by sensitive and specific biomarkers. Searching for potential biomarkers is always a hot spot in cancer research, including colorectal cancer (CRC). MicroRNAs (miRNAs) have been recently proposed as biomarkers for cancers. PATIENTS AND METHODS: Based on previous miRNA analysis in our hospital and data mining, we hypothesized that the ratio of miR-21/miR-24 (miR-21/24) may serve as plasma bio-markers in CRC patients. The plasma levels of miR-21 and miR-24 were analyzed from the 186 CRC patients before surgery and 97 healthy controls by qRT-PCR. Receiver operating characteristic (ROC) analysis was further used to evaluate the difference in diagnostic accuracy associated with the expression of miR-21, miR-24 and their ratio. Chi-square(2)-test or Fisher's exact test was performed to determine the relationship between the ratio of miR-21/24 and clinicopathological parameters. Kaplan-Meier and log-rank testing were performed to evaluate the effect of miR-21/24 ratio on the survival of colon cancer. Hazard ratios (HRs) and corresponding 95% confidence intervals (Cis) were calculated by Cox regression models. RESULTS: ROC curves revealed that the diagnostic accuracy AUC (area under the curve) in CRC tissue of miR-24, miR-21, and the ratio of miR-21/24 were 0.8971, 0.9128 and 0.9875, respectively. Notably, the ratio of miR-21/24, with the best accuracy among these miRNAs, was significantly correlated with several important prognosis factors in CRC, such as tumor size, TNM stage, lymph metastasis and histologic differentiation (all p<0.05). By Kaplan-Meier survival analysis and Cox regression analysis, the ratio of miR-21/24 was shown to be a significant survival risk factor for CRC patients. CONCLUSIONS: We showed that the plasma ratio of miR-21/24 is a potentially powerful tool for detecting CRC and predicting prognosis.