Introduction
The current screening and diagnostic methods for colorectal cancer (CRC) primarily involve tumor markers, imaging examinations, and endoscopic evaluations, which have inherent limitations. Therefore, it is imperative to explore novel diagnostic techniques for early-stage CRC to improve patient prognosis and survival rates. Recent studies have demonstrated the significant potential of circulating exosome-associated microRNAs (miRNAs) as biomarkers in CRC; however, these investigations are limited and predominantly focused on advanced tumors. Consequently, the differences in circulating exosomal miRNAs, among different stages of CRC within the classic developmental model of 'normal mucosa, adenoma, early adenocarcinoma, advanced adenocarcinoma', remain unknown.
Aims & Methods
Plasma exosomes were isolated from colorectal adenoma (CRA), early CRC (Tis-T1), advanced CRC (T2-T4), and healthy control (NC) groups (n=5 for each group) using ultracentrifugation. The miRNA expression profiles of plasma exosomes in the four groups were compared using miRNA microarray analysis to identify differentially expressed miRNAs in the three colorectal disease groups compared to the NC group. The results of miRNA microarray detection were validated by qRT-PCR to increase the sample size (n=30 for each group) and confirm the expression of characteristic miRNAs identified. Receiver operating characteristic curves were utilized to assess the diagnostic efficacy through area under curve (AUC).
Results
The extracted exosomes exhibited consistent morphology, size, and expression of protein markers that align with the fundamental characteristics of exosomes. Microarray analysis results revealed that both early and advanced CRC groups shared 31 up-regulated miRNAs and 34 down-regulated miRNAs compared to the CRA and NC groups. By intersecting with the GSE40247 dataset (CRC cell secreted exosome-derived microarray results), we identified five up-regulated miRNAs (miR-150-3p, miR-1224-5p, miR-1246, miR-1268a, and miR-1290). The expression levels of all five miRNAs showed a progressive increase with CRC advancement at different developmental stages. Notably, significant diagnostic potential was observed for miR-1224-5p, miR-1246, and miR 1290 in distinguishing patients with early CRC from NC (AUC 0.638 to 0.719). All five identified miRNAs demonstrated relatively good diagnostic performance in discriminating patients with advanced CRC from NC (AUC 0.745 to 0.838), while none of them had clear diagnostic value in distinguishing early CRC patients from individuals with CRA (AUC 0.548 to 0.654). Logistic regression analysis was employed to construct a multi-panel diagnosis model based on three specific miRNAs: miR-1224 -5p ,miR-1246, and miR-1290. The combined AUCs were found to be as follows: for discrimination between early CRC and NC groups, AUC=0.817 (P=0.0008); for discrimination between advanced CRC and NC groups, AUC=0.907 (P<0.0001); for discrimination between early CRC and CRA groups, AUC=0.754 (P=0.0035).
Conclusion
The miRNA expression profiles of plasma exosomes in early CRC patients exhibit similarities to those observed in advanced CRC patients. Specifically, the presence of miR-150-3p, miR-1224-5p, miR-1246, miR-1268a, and miR-1290 within plasma exosomes can serve as reliable indicators for the diagnosis of CRC. Importantly, a combination of miR-1224-5p, miR-1246, and miR-1290 shows promise for the early detection of CRC.
