Abstract 4955
Background
XIAP-associated factor 1 (XAF1) is a pro-apoptotic tumor suppressor whose expression is inactivated in many human malignancies. To explore the XAF1’s candidacy for a suppressor in the pathogenesis of human glioma, we investigated its expression and function in tumor cell lines and tissues.
Methods
Expression study was performed using quantitative RT-PCR and immunoblot assays. Functional interplay between XAF1 and AMPK was determined by gene transfection, siRNA-mediated depletion.
Results
XIAP-associated factor 1 (XAF1) is a pro-apoptotic tumor suppressor whose expression is inactivated in many human malignancies. In this study, we explored the XAF1’s candidacy for a suppressor in human glioma pathogenesis. XAF1 reduction is more common in high grade tumors versus low grade tumors and tightly associated with aberrant hypermethylation at 7 CpG sites in the 5’ proximal region of the promoter. XAF1 expression decreases proliferation and colony-forming ability of glioma cells while its depletion enhances cellular resistance to genotoxic drugs, such as temozolomide (TMZ), etoposide and cisplatin. The XAF1 promoter is activated in response to TMZ through JNK-IRF-1 signaling and its activation greatly increases cellular response to TMZ-induced cell death. Furthermore, XAF1 promotes autophagic cell death (ACD) by activating AMP-activated protein kinase (AMPK) in a XIAP-independent manner. Both AMPK-activating and ACD-inducing effects of XAF1 are linked to its activity to decrease intracellular ATP level, oxygen consumption, and mitochondrial membrane potential. XAF1 proteins translocate to the mitochondria and the zinc finger (ZF) 6 domain is essential for its mitochondrial distribution. Consistently, a mutant XAF1 lacking the ZF6 fails to decrease ATP level, activate AMPK, and trigger AMPK-mediated autophagic cell death. Collectively, this study demonstrates that epigenetic inactivation of XAF1 contributes to the malignant progression of human glioma by rendering tumor cells a survival advantage via the attenuation of AMPK signaling.
Conclusions
Epigenetic inactivation of XAF1 contributes to the malignant progression of human glioma by rendering tumor cells a survival advantage via the attenuation of AMPK signaling.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2018R1D1A1B07041512).
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
2273 - High performance of serial tumor biopsies in first in human (FIH) phase I trials.
Presenter: Jun Sato
Session: Poster Display session 1
Resources:
Abstract
5933 - Response rates and lesion-level progression patterns of solid tumor patients in an academic phase 1 program: implications for tumor heterogeneity
Presenter: Christopher Chen
Session: Poster Display session 1
Resources:
Abstract
3569 - Clinical Benefit and Response Rate in Early Phase Clinical Trials: First Report from a Single-Institution Study
Presenter: Antonio Marra
Session: Poster Display session 1
Resources:
Abstract
4139 - Patient (pt) selection for immunotherapeutic early-phase clinical trials (ieCTs): a single Phase I Unit experience
Presenter: Matteo Simonelli
Session: Poster Display session 1
Resources:
Abstract
4451 - Improving patient selection for immuno-oncology phase 1 trials: an external validation of five prognostic scores at Claudius Regaud Institute of Toulouse, Oncopôle (IUCT-O).
Presenter: Ghassan Al Darazi
Session: Poster Display session 1
Resources:
Abstract
1696 - Demonstrating the Changing Trends in Phase 1 Clinical Trials
Presenter: Christina Guo
Session: Poster Display session 1
Resources:
Abstract
3202 - Participation of Women in phase 1 oncology clinical trials
Presenter: Laura Vidal
Session: Poster Display session 1
Resources:
Abstract
4518 - Predictors for early trial discontinuation of patients with cancer participating in phase I clinical trials
Presenter: Joeri Douma
Session: Poster Display session 1
Resources:
Abstract
4368 - Safety of Tumor Treating Fields delivery to the torso: Meta analysis from TTFields clinical trials
Presenter: Federica Grosso
Session: Poster Display session 1
Resources:
Abstract
4615 - Proteomic Profiling Identifies Molecular Basis of Adverse Event to BPM31510 Exposure: Rationale for Comprehensive Molecular Pharmacodynamics (PD) in Phase 1 Clinical Trial Design
Presenter: Vivek Subbiah
Session: Poster Display session 1
Resources:
Abstract