Colorectal cancer (CRC) is the third and second most common cancer in males and females worldwide, respectively. Spondin-2 is a conserved secreted extracellular matrix protein and a candidate cancer biomarker. Here we found that Spondin-2 mRNA was upregulated in CRC tissues using quantitative RT-PCR and data-mining of public Oncomine microarray datasets. Spondin-2 protein was increased in CRC tissues, as revealed by immunohistochemistry analyses of two tissue microarrays containing 180 cases. Spondin-2 gene expression was significantly associated with CRC stage, T stage, M stage and Dukes stage, while its protein was associated with age and M stage. Kaplan-Meier analysis revealed that the upregulated Spondin-2 mRNA and protein predicted poor prognosis of CRC patients. Univariate and multivariate Cox regression analyses indicated that grade, recurrence, N stage and high Spondin-2 were independent predictors of overall survival of CRC patients. ELISA revealed that plasma Spondin-2 was upregulated in CRC and dropped after surgery. Receiver operating characteristic curve analysis demonstrated that plasma Spondin-2 has superior predictive performance for CRC with an area under the curve of 0.959 and the best sensitivity/specificity of 100%/90%. Furthermore, ectopic expression of Spondin-2 enhanced colon cancer cell proliferation. Spondin-2 could be an independent diagnostic and prognostic biomarker of colon cancer.
Keywords: SPON2; colorectal cancer; prognosis; protein marker; spondin-2.