Circulating lncRNA EGFR-AS1 as a diagnostic biomarker of colorectal cancer and an indicator of tumor burden

BACKGROUND: Colorectal cancer (CRC) is one of the most common malignancies. Although CRC treatment has been significantly improved, patient survival remains low because most patients already have advanced disease at diagnosis. Early screening and diagnosis of tumors is critical; however, the current tissue biopsy and radiological evaluation methods have very limited effectiveness. Therefore, establishing new convenient and non-invasive biomarkers is urgently needed for timely detection, therapeutic assessment, and prognostic prediction. At present, non-coding RNAs (ncRNAs) have attracted research attention owing to their potential oncological applications. METHODS: The long ncRNA epidermal growth factor receptor antisense RNA 1 (EGFR-AS1) is overexpressed in multiple malignancies including CRC. The present study examined the circulating EGFR-AS1 level in CRC, and the results showed that EGFR-AS1 could be considered an indicator of tumor burden. RESULTS: Elevated circulating EGFR-AS1 levels were detected in CRC cases (n=128) compared with control cases comprising endoscopy confirmed CRC-free individuals [n=64, median expression normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 1.578 vs. 0.780, P<0.001]. Individuals with larger tumors (≥5 cm) had elevated circulating EGFR-AS1 levels compared to those with smaller tumors (<5 cm, 1.739 vs. 1.290, P<0.001). The expression of serum EGFR-AS1 in stage III/IV CRC was higher than that in stage I/II CRC (1.691 vs. 1.412, P<0.05). Plasma EGFR-AS1 levels were markedly reduced following surgical resection of colorectal lesions in a subset of patients [n=32, 1.192 (pre-surgery) vs. 0.692, P<0.001]. Furthermore, the expression of EGFR-AS1 in resected CRC tissues was significantly higher than that in paracancerous tissues (n=32, 1.336 vs. 0.487, P<0.001). CONCLUSIONS: These results highlight the potential of EGFR-AS1 as a diagnostic biomarker in CRC.