Increased expression of epidermal growth factor-like domain-containing protein 7 is predictive of poor prognosis in patients with hepatocellular carcinoma.

Abstract

Epidermal growth factor-like domain-containing protein 7 (EGFL7) is an endothelial cell-derived secreted factor that regulates vascular tube formation. In human cancer, the specificity of expression is lost as EGFL7 has been detected in tumor cells, in addition to endothelial cells. This study evaluated the intricate relationship between hypoxia-inducible factor 1-alpha (HIF-1α) and EGFL7 under both hyperoxia and hypoxia states. In the present study, immunohistochemical staining and ELISA were applied to examine the relative level of EGFL7 in 182 cases of hepatocellular carcinoma (HCC) formalin-fixed and paraffin-embedded tissues and 110 cases of HCC serum samples. Quantitative polymerase chain reaction and Western blotting were applied to verify the correlation between serum EGFL7 level and anoxic microenvironment. Immunohistochemical staining was performed to determine the correlation between EGFL7 and HIF1-α. The correlations between EGFL7 expression and patients' age, tumor size, gender, N-stage, history of cirrhosis, M-stage, history of hepatitis C, and history of hepatitis B were statistically insignificant (P = 0.28, 0.34, 0.71, 0.15, 0.8, 0.2, 0.052, and 0.14, respectively). High level of EGFL7 was significantly correlated with overall survival as well as disease-free survival in 182 HCC patients (P = 0.0016 and P < 0.001, respectively). The correlations between serum EGFL7 and vascular invasion and extrahepatic metastasis were statistically significant (P < 0.0001). Among the 35 HIF1-α-positive HCC patients, 69% were medium positive and 31% were strong positive. EGFL7 protein expression level was oxygen dependent in HCC line (P < 0.05). EGFL7 was found to be a potential predictor for HCC survival and metastasis state; EGFL7 may be a promising biomarker and therapeutic target in human HCC.