Overexpression of SEZ6L2 predicts poor prognosis in patients with cholangiocarcinoma

Background: With the feature of destructive and biliary malignancy, intrahepatic cholangiocarcinoma (ICC), presents unclear molecular mechanisms which contributes to typically poor prognosis for patients. Seizure-related 6 homolog-like 2 (SEZ6L2) is a gene that encodes for a seizure-associated protein localized on the cell surface. Thus far, the function of SEZ6L2 in ICC has not been reported. Methods: We used data from The Cancer Genome Atlas and the Gene Expression Omnibus to analyze dynamics behind and levels of expression of SEZ6L2 in ICC. Then we used qRT-PCR and Immunohistochemical staining to detect levels of expression of SEZ6L2 and thereby determined the potential clinical significance of this protein in ICC. Results: According to qRT-PCR and immunohistochemical analysis results, SEZ6L2 was overexpressed in ICC. Kaplan-Meier and Cox proportional hazard analyses indicated that patients afflicted by ICC with high levels of relative expression of SEZ6L2 have a poorer prognosis and that SEZ6L2 may be an independent prognostic factor which enables to the accurate prediction of overall survival (OS) and disease-free survivals' (DFS) expected rates. Subcutaneous xenograft models used to explore the role of SEZ6L2 in tumor formation in vivo. The dynamics of the SEZ6L2 gene being promote angiogenesis in cholangiocarcinoma are related to increasing expressive growth factors which include EGF, VEGF, PDGF and the activation of the P38-MAPK pathway. Conclusions: Our findings suggest that SEZ6L2 can serve as an advanced biomarker that can be used to accurately predict a patient prognosis and be used as a target for ICC treatment.