Rectal swab gene expression as a non-invasive biomarker for CRC screening

Abstract

BACKGROUND: Aberrant gene levels in rectal swab specimens are potential non-invasive biomarkers for the early detection of colorectal cancer. The aim of this study was to investigate the expression level of dysregulated genes in CRC in rectal swab specimens from normal subjects and CRC patients, and evaluate the potential of this approach as a non-invasive biomarker for CRC diagnosis. METHODS: We performed RNA extraction and reverse transcription of the rectal swab specimens, then applied quantitative polymerase chain reaction to determine the expression level of 15 genes which have been previously reported to show dysregulation during CRC development. RESULTS: Our results showed that CD44, IL8, CXCR2 and c-myc were significantly overexpressed in rectal swab specimens of CRC patients when compared to control subjects in both the training and validation studies, suggesting that gene levels of these four genes were potential biomarker to discriminate CRC from non-CRC subjects. Further evaluation showed that a panel of these 4 genes was able to identify CRC patients with an area under the curve of 0.74 for the training study and 0.79 for the validation study. Finally, we tested the predictive value of the 4-gene signature in a prediction study of 55 subjects (including 25 CRC patients and 30 non-CRC control subjects). The 4-gene signature correctly identified 16 of 20 CRC patients (80% sensitivity) and 29 of 35 non-CRC subjects (82.9% specificity). CONCLUSION: Our data demonstrated the promising potential of the gene signature in rectal swab specimens as a noninvasive biomarker for CRC diagnosis.