Personalized and Precision Medicine Journal

Abstract Background: Circulating microRNAs have emerged as promising minimally invasive biomarkers for colorectal cancer (CRC). This study evaluated the expression and diagnostic performance of circulating hsa-miR-21-5p and investigated its potential molecular targets using integrated bioinformatics analysis.
Methods: Plasma samples were obtained from 50 treatment-naïve male patients with histologically confirmed grade II CRC and 20 healthy male controls. Circulating RNA was extracted and miR-21-5p expression was quantified using stem-loop reverse transcription quantitative PCR. Hsa-miR-1228-3p was used as the endogenous reference, and relative expression was calculated using the 2^−ΔΔCq method. Diagnostic performance was assessed by receiver operating characteristic analysis. High-confidence target genes were identified using miRDB and TargetScan, followed by protein–protein interaction analysis using STRING.
Results: The mean ages of patients and controls were 55 and 49 years, respectively, with no significant between-group difference (P=0.162). Circulating miR-21-5p expression was significantly higher in CRC patients than in healthy controls (P=0.002). ROC analysis yielded an area under the curve of 0.873 (95% CI, 0.766–0.979; P<0.0001). Target prediction identified a set of high-confidence genes involved in cell proliferation, apoptosis, immune regulation, adhesion, extracellular-matrix organization, and transcriptional control. STRING analysis revealed a functionally connected network containing central signaling proteins, including STAT3, YAP1, SKP2, PDCD4, TRAF6, and SPRY-family proteins.
Conclusion: Circulating miR-21-5p demonstrated good ability to distinguish CRC patients from healthy controls. The bioinformatics findings suggest that its biological effects may involve interconnected oncogenic, apoptotic, immune, and invasion-related pathways.