Differential expression of miR-144* as a novel fecal-based diagnostic marker for colorectal cancer.

Background: MicroRNAs (miRNA) are tiny, noncoding, small, endogenous RNAs that play major roles in neoplastic transformation and could therefore offer a better quantitative and noninvasive method for the diagnosis and prognosis of colorectal cancer (CRC) using feces. In the present study, we screened feces for 648 miRNAs and analyzed the role of miR-144* as a potential CRC diagnostic marker.

Methods: Fecal miRNA expression was profiled with RT-pre-amplification-qPCR, and the stability was determined using both endogenous and exogenous miRNA by RT-qPCR. ROC analysis was performed to enhance the diagnosing power of the CRC patients' fecal specimens.

Results: We detected 39% of all the miRNAs screened in feces. Endogenous miRNAs are more stable over time and temperature, while exogenous miRNAs degraded rapidly. miR-144* was overexpressed in feces, suggesting that it could be a potent candidate diagnostic marker for CRC detection, with a sensitivity of 74% and a specificity of 87% (n = 75, p < 0.0001). Moreover, RT-qPCR analysis showed that miR-144* was also overexpressed in paired CRC tissues, thus suggesting its possible utilization as a diagnostic marker.

Conclusions: We demonstrated that miRNAs are stable in the fecal microenvironment, and that, among them, miR-144* represents a novel fecal-based diagnostic marker for CRC screening. Nevertheless, our data need to be validated in a large cohort of subjects.