Functional expression of TRAIL receptors TRAIL-R1 and TRAIL-R2 in esophageal adenocarcinoma

The tumour necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL/Apo2L) is a member of the TNF superfamily that preferentially induces apoptosis in cancer cells, while sparing normal cells. TRAIL induces apoptosis by interacting with its receptors TRAIL-R1 and TRAIL-R2. Recently, new humanized agonistic anti-TRAIL-R1 and anti-TRAIL-R2 antibodies have been developed, and are undergoing phase I/II clinical trails. Esophageal adenocarcinoma (EA) is associated with significantly poor outcome and is rapidly increasing in incidence in the United States and Western Europe, with virtually no effective non-surgical treatment. The aim of this study was to determine whether human EA tissue express TRAIL-R1 and/or TRAIL-R2, and whether EA cell lines Bic-1 and Seg-1 expresses functional TRAIL-R1 and/or TRAIL-R2. The expression of TRAIL-R1 and TRAIL-R2 was determined in sections from 18 human EA by immunohistochemistry (IHC). Sixteen (89%) of the EA expressed TRAIL-R1 and 17 (94%) expressed TRAIL-R2. Both cell lines were found to express TRAIL-R1 and TRAIL-R2 by western blot analysis, IHC, and flow cytometry. The fully human agonistic TRAIL-R1 (HGS-ETR1) and TRAIL-R2 (HGS-ETR2) antibodies induced apoptosis in Bic-1 and Seg-1 cells in a time and dose dependent manner. Our results show that the vast majority of primary human EA express TRAIL-R1 and TRAIL-R2 and that EA cells lines express functional TRAIL-R1 and TRAIL-R2. Targeting of these receptors by agonist monoclonal antibodies may be of therapeutic value in patients with EA.