Abstract 4808
Background
NORE1A/RASSF5 is a tumor suppressor that is commonly inactivated in a variety of cancers. NORE1A is frequently down-regulated during tumor development and its inactivation often correlates with up-regulation of Ras activity. Although NORE1A was reported to be activated by NF-kB, its role in NF-kB signaling and the underlying mechanism have not been addressed. In this study, we explored the role for NORE1A in the regulation and function of the TNF-NF-kB pathway.
Methods
NORE1A effect on TNF regulation of inflammation, growth, and apoptosis was examined by flow cytometry, migration and invasion, and apoptosis assays. NORE1A regulation of TNF-NF-kB signaling was analyzed by quantitative RT-PCR, immunoblot, immunoprecipitation, and promoter luciferase assay.
Results
Upon exposure to TNF-a, NORE1A is induced by NF-kB signaling at the level of transcription while its activation suppresses TNF activation of NF-kB, indicating that NORE1A functions as a feedback terminator of TNF-NF-kB signaling. As predicted, NORE1A blocks TNF activation of pro-inflammatory gene transcription, epithelial-to-mesenchymal transition (EMT), invasion and migration. Mechanistically, NORE1A binds directly to TNF receptor I (TNFR1) and ubiquitin E3 ligase ITCH to promote ITCH-mediated K48-linked ubiquitination of TNFR1 and subsequent lysosomal degradation. Additionally, we identified that the PPXY motif of NORE1A interacts directly with ITCH using a series of deletion mutants. This interaction protects BAX from ITCH-mediated ubiquitination and thus activates its apoptotic function. NORE1A interaction with ITCH plays a crucial role for both TNFR1 degradation and BAX stabilization and activation.
Conclusions
In this study, we demonstrate first that NORE1A is a feedback terminator of TNF-NF-kB signaling, which directly antagonizes TNFR1 by facilitating the ITCH-TNFR1 interaction. Our study also shows that NORE1A binding to ITCH releases ITCH from BAX and activates BAX-mediated apoptosis. These data illuminate the mechanistic consequence of NORE1A inactivation in tumorigenesis.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Sung-gil, Chi.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
2831 - Interleukin-6 as a Predictive Marker for Early Response to Induction Chemotherapy in Acute Myeloblastic Leukaemia
Presenter: Salah Khallaf
Session: Poster Display session 1
Resources:
Abstract
6014 - Impact of FLT3-ITD mutation on post-transplant outcome of adult AML is modified by the concomitant NPM1 mutation and pre-transplant remission status: A report from Taiwan Bone Marrow Transplant Registry (TBMTR)
Presenter: Su-peng Yeh
Session: Poster Display session 1
Resources:
Abstract
2914 - Efficacy endpoints studied in clinical trials for early-onset leukaemia
Presenter: Dylan Said
Session: Poster Display session 1
Resources:
Abstract
4691 - High triglyceride is a major risk factor of DIC and differentiation syndrome in acute promyelocytic leukemia
Presenter: Tomohiro Yamakawa
Session: Poster Display session 1
Resources:
Abstract
4395 - DREAMM 4: A Phase I/II single-arm open-label study to explore safety and clinical activity of belantamab mafodotin (GSK2857916) administered in combination with pembrolizumab in patients with relapsed/refractory multiple myeloma (RRMM)
Presenter: Suzanne Trudel
Session: Poster Display session 1
Resources:
Abstract
2808 - A Phase 1 Study of HMPL-523, a Selective Oral Anti-Spleen Tyrosine Kinase Inhibitor, in Patients with Relapsed or Refractory Lymphoma
Presenter: Nathan Fowler
Session: Poster Display session 1
Resources:
Abstract
4403 - A Phase 1 Study of HMPL-689, a Selective Oral Phosphoinositide 3-Kinase-Delta Inhibitor, in Patients with Relapsed or Refractory Lymphoma
Presenter: Jonathon Cohen
Session: Poster Display session 1
Resources:
Abstract
3357 - A global patient-driven Facebook study in a very rare sarcoma: Health-related quality of life in Epithelioid Hemangioendothelioma (EHE) patients
Presenter: Marije Weidema
Session: Poster Display session 1
Resources:
Abstract
2475 - Qualitative study of patients’ experiences of living with and beyond a soft tissue sarcoma diagnosis: the impact of sarcoma specialist services
Presenter: Ana Martins
Session: Poster Display session 1
Resources:
Abstract
2640 - Health-related quality of life issues of patients affected by desmoid-type fibromatosis; experiences from two countries
Presenter: Milea Timbergen
Session: Poster Display session 1
Resources:
Abstract