Circulating exosomal PCAT1 as a complement of carcinoembryonic antigen for early colorectal cancer diagnosis

Backgrounds: Given the global prevalence of colorectal cancer (CRC), advancements in prompt and accurate diagnosis are crucial. Long non-coding RNAs (lncRNAs) in serum exosomes are emerging as potential diagnostic biomarkers. This study evaluated the feasibility of using serum exosomal lncRNAs for early-stage CRC diagnosis in clinical practice. Methods: Candidate serum exosomal lncRNAs were identified through an integrated analysis of two GEO datasets (GSE100206 and GSE100063) containing non-coding RNA expression profiles in serum exosomes. Exosomes isolated from participants' serum were validated using transmission electron microscopy (TEM) and immunoblotting. The expression levels of serum exosomal PCAT1 were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Diagnostic accuracy was assessed using receiver operating characteristic (ROC) analysis. Results: Serum exosomal PCAT1 levels were evaluated in 150 CRC patients, 66 patients with benign colorectal lesions, and 128 healthy controls. ROC analysis demonstrated high diagnostic efficacy of serum exosomal PCAT1 for CRC. Notably, the predictive performance was sufficient to distinguish early-stage CRC patients. Additionally, the diagnostic value was significant for CRC patients with low serum carcinoembryonic antigen (CEA) levels. Measuring serum exosomal PCAT1 could complement CEA assessment, enhancing CRC diagnostic accuracy. Conclusions: Serum exosomal PCAT1 can complement CEA assessment, aiding in early CRC diagnosis and helping to differentiate the disease, especially in patients with low CEA levels.