Expression of the eukaryotic translation initiation factor 4E (eIF4E) and 4E-BP1 in esophageal cancer

Objectives: The eukaryotic initiation factor 4E (eIF4E) has been shown to play a key role in cell growth, and several studies have documented an increased expression of eIF4E in a number of solid tumors, including breast, bladder, cervical and head and neck cancers. The aim of this study was to determine the level of expression of eIF4E and eIF4E-binding protein 1 (4E-BP1) in esophageal cancer. Design and methods: Tumor and normal adjacent tissue samples (as controls) were obtained from 99 patients with esophageal cancer. eIF4E and 4E-BP1 levels were determined by using Western blot analysis. eIF4E was purified by affinity chromatography using m7GTP-sepharose, and the levels of 4E-BP1 bound to eIF4E were determined. Results: In cancerous esophageal tissues, eIF4E level was elevated by a mean of 12.59 ± 1.66-fold, and 4E-BP1 was elevated by a mean of 15.76 ± 2.45-fold when compared to normal adjacent tissues. Both eIF4E and 4E-BP1 expressions were higher in cancerous compared to noncancerous esophageal tissues. Conclusions: A higher expression of eIF4E was correlated with advanced stages. The inverse relationship found between the increases in 4E-BP1 levels observed in esophagus tumors and lymph node involvement would support the hypothesis that the overexpression of eIF4E can be involved in tumorigenesis and a possible role of 4E-BP1 as a prognostic factor in esophageal cancer.