BIRC7 and STC2 expression is associated with tumorigenesis and poor outcome in extrahepatic cholangiocarcinoma

Background: Extrahepatic cholangiocarcinoma (EHCC) is a highly aggressive epithelial malignancy and has a poor prognosis for their insensitivity to therapies and difficulty in detection. Novel targets and biomarkers are urgently needed to develop for functional, diagnostic and prognostic application on EHCC. Methods: 100 EHCC tissues，30 peritumoral tissues, 10 adenoma and 15 normal biliary tract tissues were assayed using EnVision immunohistochemistry. Results: The expression of BIRC7 and STC2 proteins were higher in EHCC tissues than those in peritumoral tissues, adenoma and normal biliary tract tissues. The positive rates of BIRC7 and STC2 expression were significantly higher in cases with lymph node metastasis, invasion to surrounding tissues/organs, and TNM stage III and/or IV and unable to undergo resection (biopsy only). Kaplan-Meier survival curves demonstrated that the overall survival of positive-BIRC7 or positive-STC2 patients was significantly lower than those of negative-BIRC7 or negative-STC2, respectively. Cox-proportional regression analysis demonstrated that positive-BIRC7 and positive-STC2 expression, along with poor differentiation of EHCC, tumor size >3cm, lymph node metastasis, invasion to surrounding tissues/organs and unable to undergo resection are independent prognostic factors of EHCC patients. Conclusions: BIRC7 and STC2 are involved in the tumorigenesis and progression of EHCC, and positive expression of BIRC7 and STC2 are associated with poor prognosis in patients with EHCC. BIRC7 and STC2 might be a potential tumor biomarker for EHCC diagnosis and prognosis.