Serum miR-21, miR-29a, and miR-125b Are Promising Biomarkers for the Early Detection of Colorectal Neoplasia

Circulating microRNAs (miRNA) are emerging as promising diagnostic biomarkers for colorectal cancer, but their usefulness for detecting early colorectal neoplasms remains unclear. This study aimed to identify serum miRNA biomarkers for the identification of patients with early colorectal neoplasms. A cohort of 237 serum samples from 160 patients with early colorectal neoplasms (148 precancerous lesions and 12 cancers) and 77 healthy subjects was analyzed in a three-step approach that included a comprehensive literature review for published biomarkers, a screening phase, and a validation phase. RNA was extracted from sera, and levels of miRNAs were examined by real-time RT-PCR. Nine miRNAs (miR-18a, miR-19a, miR-19b, miR-20a, miR-21, miR-24, miR-29a, miR-92, and miR-125b) were selected as candidate biomarkers for initial analysis. In the screening phase, serum levels of miR-21, miR-29a, and miR-125b were significantly higher in patients with early colorectal neoplasm than in healthy controls. Elevated levels of miR-21, miR-29a, and miR-125b were confirmed in the validation phase using an independent set of subjects. Area under the curve (AUC) values for serum miR-21, miR-29a, miR-125b, and their combined score in discriminating patients with early colorectal neoplasm from healthy controls were 0.706, 0.741, 0.806, and 0.827, respectively. Serum levels of miR-29a and miR-125b were significantly higher in patients who had only small colorectal neoplasms (≤5 mm) than in healthy subjects. Because serum levels of miR-21, miR-29a, and miR-125b discriminated patients with early colorectal neoplasm from healthy controls, our data highlight the potential clinical use of these molecular signatures for noninvasive screening of patients with colorectal neoplasia.