Abstract
No ideal serum markers for screening colorectal cancer (CRC) have been identified. The aim of this study was to determine the usefulness of endothelial cell-specific molecule-1 (ESM-1) as a serum marker for CRC. Illumina microarray was carried out to search CRC-related biomarkers. cDNA microarray detected that ESM-1 was one of the overexpressed genes in CRC. Overexpression of ESM-1 mRNA was confirmed in tissues of CRC by RT-PCR and real-time PCR. Immunohistochemical staining showed strong expression of ESM-1 in the cytoplasm of tumor cells. Overexpression of ESM-1 in human serum with CRC was found by Western blot analysis. For quantitative analysis of ESM-1 in serum, we determined the ESM-1 levels in serum specimens using an ELISA kit. We showed that the ESM-1 levels in the serum of patients with CRC were significantly elevated (70.1 ± 29.7 pg/mL) compared to healthy subjects (29.7 ± 14.9 pg/mL). The accuracy, sensitivity, and specificity of ESM-1 for CRC were 0.94, 99%, and 73%, respectively, by receiver operating characteristics curve analysis. The positive predictive value and negative predictive value were 63% and 95%, respectively. The likelihood ratios of a positive or negative test result were 73 and 0.27, respectively. When analyzed with a Cox regression model, a higher serum ESM-1 level (≥76.0 pg/mL) was correlated with poor prognosis. This study suggests that expression of ESM-1 is increased in tissue and serum of CRC patients and that ESM-1 can be used as a potential serum marker for the early detection of CRC.