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
1851 - Nivolumab-induced and radiation recall pneumonitis in patients with non-small cell lung cancer: a multicenter real world analysis of 669 patients
Presenter: Nobuaki Mamesaya
Session: Poster Display session 1
Resources:
Abstract
851 - Retrospective analysis of immunotherapy prognostic scores in advanced NSCLC at Nottingham University Hospitals (UK)
Presenter: Cristina Lopez Escola
Session: Poster Display session 1
Resources:
Abstract
3639 - Applicability of lung immune prognostic index (LIPI) to predict efficacy of first-line pembrolizumab in advanced non-small-cell lung cancer (NSCLC)
Presenter: Xabier Mielgo Rubio
Session: Poster Display session 1
Resources:
Abstract
2950 - Delayed Onset Immune Related Adverse Effects (IRAEs) of Pembrolizumab in Non-Small Cell Lung Cancer
Presenter: Haixi Yan
Session: Poster Display session 1
Resources:
Abstract
3659 - Clinical implication of multiplex IHC and serologic biomarkers on Hyperprogression in NSCLC patients receiving Immune checkpoint blockers in real world.
Presenter: Joori Kim
Session: Poster Display session 1
Resources:
Abstract
4882 - Local ablative treatment and treatment beyond progression for oligo-progression in stage IV non-small cell lung cancer after tumor response to anti-PD1 treatment
Presenter: Florian Guisier
Session: Poster Display session 1
Resources:
Abstract
1358 - Atezolizumab in combination with chemotherapy for first-line treatment of advanced non-small cell lung cancer: A systematic review and meta-analysis of randomized controlled trials (RCTs)
Presenter: Francis Mogollon-Duffo
Session: Poster Display session 1
Resources:
Abstract
2170 - Prognostic Impact of Metastatic Sites for Pembrolizumab Efficacy as First-line therapy in Patients with PD-L1 tumor proportion score (TPS) ≥ 50% Advanced Non–Small Cell Lung Cancer: A Retrospective Multicenter Study
Presenter: Hayato Kawachi
Session: Poster Display session 1
Resources:
Abstract
3051 - Impact of visceral fat area as independent predictive factor in patients with advanced non-small cell lung cancer treated with nivolumab
Presenter: Yuki Sato
Session: Poster Display session 1
Resources:
Abstract
3409 - Effect and safety of immune checkpoint inhibitors for brain metastases from non-small cell lung cancer
Presenter: Toshihiko Iuchi
Session: Poster Display session 1
Resources:
Abstract