C-Rel is a critical mediator of NF-κB-dependent TRAIL resistance of pancreatic cancer cells.

C Geismann,G Wirths,P Rosenstiel,A Dreher,A Trauzold,H Schäfer,S Schreiber,G Schneider,J-H Egberts,R Häsler,B Sipos,C Hauser,A Arlt,S Zeissig,S Sebens,F Grohmann

doi:10.1038/cddis.2014.417

Abstract

Pancreatic ductal adenocarcinoma (PDAC) represents one of the deadliest malignancies with an overall life expectancy of 6 months despite current therapies. NF-κB signalling has been shown to be critical for this profound cell-autonomous resistance against chemotherapeutic drugs and death receptor-induced apoptosis, but little is known about the role of the c-Rel subunit in solid cancer and PDAC apoptosis control. In the present study, by analysis of genome-wide patterns of c-Rel-dependent gene expression, we were able to establish c-Rel as a critical regulator of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in PDAC. TRAIL-resistant cells exhibited a strong TRAIL-inducible NF-κB activity, whereas TRAIL-sensitive cells displayed only a small increase in NF-κB-binding activity. Transfection with siRNA against c-Rel sensitized the TRAIL-resistant cells in a manner comparable to siRNA targeting the p65/RelA subunit. Gel-shift analysis revealed that c-Rel is part of the TRAIL-inducible NF-κB complex in PDAC. Array analysis identified NFATc2 as a c-Rel target gene among the 12 strongest TRAIL-inducible genes in apoptosis-resistant cells. In line, siRNA targeting c-Rel strongly reduced TRAIL-induced NFATc2 activity in TRAIL-resistant PDAC cells. Furthermore, siRNA targeting NFATc2 sensitized these PDAC cells against TRAIL-induced apoptosis. Finally, TRAIL-induced expression of COX-2 was diminished through siRNA targeting c-Rel or NFATc2 and pharmacologic inhibition of COX-2 with celecoxib or siRNA targeting COX-2, enhanced TRAIL apoptosis. In conclusion, we were able to delineate a novel c-Rel-, NFATc2- and COX-2-dependent antiapoptotic signalling pathway in PDAC with broad clinical implications for pharmaceutical intervention strategies.

Highlights

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant tumour diseases representing the fourth leading cause in the statistics of cancer-related death in western countries.[1]
Whilst tumour necrosis factor-related apoptosisinducing ligand (TRAIL) and TNF-α mostly activate the canonical pathway, a subset of TNF receptor superfamily members activate the non-canonical or alternative pathway through NF-κB-inducing kinase, which interacts with IKKα and in turns leads to the degradation of the p52 precursor protein p100
The role of RelA in different aspects of PDAC is well established[4,6,14,41] and recent reports indicate a role of RelB in PDAC development, growth and apoptotic response,[14,15,16] only limited reports on such a role of c-Rel in other solid cancers[42,43,44] and none in PDAC exist

Summary

Introduction

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant tumour diseases representing the fourth leading cause in the statistics of cancer-related death in western countries.[1]. A pivotal role in carcinogenesis and chemoresistance of a great number of tumours, including PDAC, has been shown for NF-κB.[4,6,8,9,10] This transcription factor is composed as a hetero- or homodimer of members of the so-called Rel family.[4,6,11] Proteins of this family harbour a Rel homology domain, which mediates dimerization as well as the interaction with inhibitory components of the pathway Five members of this family – RelA/p65, RelB, c-Rel, NF-κB1 (p50/p105) and NF-κB2 (p52/p100) – are known. The non-canonical pathway is mainly involved in specific immunologic processes, but there is growing evidence that it might be involved in PDAC development and apoptosis resistance as well.[12,13,14,15,16,17]

Methods

Results

Conclusion