ASK1 regulates the survival of neuroblastoma cells by interacting with TLX and stabilizing HIF-1α

Praveen K Sobhan; Qiwei Zhai; Lydia C Green; Loen M Hansford; Keiko Funa

doi:10.1016/j.cellsig.2016.11.018

ASK1 regulates the survival of neuroblastoma cells by interacting with TLX and stabilizing HIF-1α

Cell Signal. 2017 Jan:30:104-117. doi: 10.1016/j.cellsig.2016.11.018. Epub 2016 Nov 24.

Authors

Praveen K Sobhan¹, Qiwei Zhai², Lydia C Green³, Loen M Hansford⁴, Keiko Funa⁵

Affiliations

¹ Sahlgrenska Cancer Center, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden. Electronic address: kspraveen01@gmail.com.
² Sahlgrenska Cancer Center, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden. Electronic address: qiwei.zhai@gu.se.
³ Sahlgrenska Cancer Center, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden. Electronic address: lydia.green@gu.se.
⁴ Program in Neurosciences and Mental Health, The Hospital for Sick Children, University of Toronto, Toronto, Canada. Electronic address: loen.hansford@gmail.com.
⁵ Sahlgrenska Cancer Center, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden; Oncology Laboratory, Department of Pathology, Sahlgrenska University Hospital, SE 413 45 Gothenburg, Sweden. Electronic address: keiko.funa@gu.se.

PMID: 27890558
DOI: 10.1016/j.cellsig.2016.11.018

Abstract

Elevated expression of TLX (also called as NR2E1) in neuroblastoma (NB) correlates with unfavorable prognosis, and TLX is required for self-renewal of NB cells. Knockdown of TLX has been shown to reduce the NB sphere-forming ability. ASK1 (MAP3K5) and TLX expression are both enhanced in SP (side population) NB and patient-derived primary NB sphere cell lines, but the majority of non-SP NB lines express lower ASK1 expression. We found that ASK1 phosphorylated and stabilized TLX, which led induction of HIF-1α, and its downstream VEGF-A in an Akt dependent manner. In depleting ASK1 upon hypoxia, TLX decreased and the apoptosis ratio of NB cells was enhanced, while low-ASK1-expressing NB cell lines were refractory in TUNEL assay by using flow cytometry. Interestingly, primary NB spheres cell lines express only high levels of active pASK1Thr-838 but the established cell lines expressed inhibitory pASK1Ser-966, and both could be targeted by ASK1 depletion. We report a novel pro-survival role of ASK1 in the tumorigenic NB cell populations, which may be applied as a therapeutic target, inducing apoptosis specifically in cancer stem cells.

Keywords: ASK1; Apoptosis; HIF-1α; Neuroblastoma; TLX.

MeSH terms

Animals
Apoptosis / drug effects
Basic Helix-Loop-Helix Transcription Factors / metabolism
Benzimidazoles / metabolism
Carbocyanines / metabolism
Cell Line, Tumor
Cell Survival / drug effects
Gene Silencing / drug effects
Humans
Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
MAP Kinase Kinase Kinase 5 / chemistry
MAP Kinase Kinase Kinase 5 / metabolism*
Membrane Potential, Mitochondrial / drug effects
Mice, SCID
Neuroblastoma / metabolism*
Neuroblastoma / pathology*
Orphan Nuclear Receptors
Phosphorylation / drug effects
Protein Binding / drug effects
Protein Domains
Protein Kinase Inhibitors / pharmacology
Protein Stability / drug effects
Proto-Oncogene Proteins c-akt / metabolism
Receptors, Cytoplasmic and Nuclear / metabolism*
Up-Regulation / drug effects
Xenograft Model Antitumor Assays

Substances

Basic Helix-Loop-Helix Transcription Factors
Benzimidazoles
Carbocyanines
Hypoxia-Inducible Factor 1, alpha Subunit
NR2E1 protein, human
Orphan Nuclear Receptors
Protein Kinase Inhibitors
Receptors, Cytoplasmic and Nuclear
endothelial PAS domain-containing protein 1
5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine
Proto-Oncogene Proteins c-akt
MAP Kinase Kinase Kinase 5
MAP3K5 protein, human