Abstract
Circulating miRNA expression is most commonly measured by qRT-PCR, however, the lack of a suitable endogenous control hinders people from evaluating the accurate changes in miRNA expression levels and developing the non-invasive biomarkers. In this study, we aimed to screen the specific, highly stable endogenous control in esophageal squamous cell carcinoma (ESCC) to overcome the obstacle. We selected "housekeeping" miRNAs according to the published database and initially acquired 21 miRNAs. Subsequently, we screened these miRNAs using GSE106817 and TCGA datasets according to specific inclusion criteria and evaluated the suitability of "candidate" miRNAs. Among these miRNAs, the average abundance of miR-423-5p was relatively high in serum. Notably, miR-423-5p expression in serum showed no significant difference between ESCC patients and healthy controls (n = 188, P = 0.29). Moreover, among these miRNAs, miR-423-5p was the most stable miRNA using the NormFinder algorithms. Overall, these results indicate that miR-423-5p, as a novel and optimal endogenous control, could be used to quantify circulating miRNAs in ESCC.