hsTRAIL/Apo2L Induces Apoptosis in Enteropathy-Associated T-Cell Lymphoma

Abstract 1665

EATL is an intestinal tumor of aberrant intraepithelial T-lymphocytes (IELs) and may be preceded by refractory celiac disease type II (RCD II). Current therapies include surgery, chemotherapy and autologous and/or allogeneic stem cell transplantation. Despite these therapies, the overall outcome of EATL is very poor with 1- and 5-year survival rates in the range of 31–39% and 8–20%, respectively. Therefore, new therapeutic options are needed. Human soluble tumor necrosis factor-related apoptosis-inducing ligand, hsTRAIL/Apo2L, a member of the TNF family, has proven to selectively kill tumor cells via an alternative, death-receptor mediated apoptosis pathway. In this present study we evaluated if hsTRAIL/Apo2L induces apoptosis in both isolated lymphoma cells of EATL biopsies and isolated cells of RCD II biopsies.

hsTRAIL/Apo2L induced apoptosis in isolated EATL lymphoma cells. RCD II cells were less sensitive to hsTRAIL/Apo2L compared to EATL cells. hsTRAIL/Apo2L induced apoptosis in EATL cells was caspase-9 dependent, but unexpectedly active caspase-8 involvement could not be detected. RT-MLPA analysis on EATL samples confirmed this observation by showing increased levels of c-Flip in EATL cells, which suggests a blockage in the extrinsic apoptosis pathway. Both EATL and RCDII cells showed expression of TRAIL receptors R1 and R2 and almost no expression of R3 and R4.

In conclusion, our study showed that hsTRAIL/Apo2L induces apoptosis in EATL cells through the intrinsic apoptosis pathway. Moreover, we showed that TRAIL receptor R1 and R2 are expressed in EATL cells. Based on these results, hsTRAIL/Apo2L may be a new therapeutic option for EATL patients.