Assessment of stanniocalcin-1 as a prognostic marker in human esophageal squamous cell carcinoma

Stanniocalcin-1 (STC1) is a secreted glycoprotein hormone and highly expressedin various types of human malignancies. Although evidence points to the role ofSTC1 in human cancers, the clinical significance of STC1 expression in esophagealcancer has not been well established. Quantitative reverse transcriptase-polymerasechain reaction and immunohistochemistry were performed to assess the expressionof STC1 in the cancer cell line TE8 and esophageal cancer tissues from 229 esophagealsquamous cell carcinomas (ESCC). Surgically-resected tissue sections were immunostainedfor potential regulators of STC1 expression, hypoxia-inducible factor-1α (HIF-1α)and p53. Marked increase in STC1 mRNA and protein expression was noted in TE8cells cultured under hypoxic conditions. Overexpression of STC1 mRNA was notedin ESCC tumors compared to normal counterparts. Positive immunohistochemical stainingfor STC1 protein was observed in 38.9% of patients, and correlated significantlywith advanced pT status (p=0.019), poor prognosis [overall survival (p<0.0006)and disease-free survival (p<0.0002) of ESCC patients who had undergone curativesurgery]. Positive staining for HIF-1α and p53 proteins in ESCC did not correlatewith STC1 expression. The results showed marked induction of STC1 expression underhypoxia in cultured cells and in esophageal cancer cells and that overexpressionof STC1 was an independent prognostic factor in patients with esophageal cancerwho had undergone curative surgery. STC1 is a potentially useful biomarker forESCC treatment.