Hypoxia modulates EWS-FLI1 transcriptional signature and enhances the malignant properties of Ewing's sarcoma cells in vitro.
Hypoxia is an important condition in the tumor cell microenvironment and approximately 1% to 1.5% of the genome is transcriptionally responsive to hypoxia with hypoxia-inducible factor-1 (HIF-1) as a major mediator of transcriptional activation. Tumor hypoxia is associated with a more aggressive phenotype of many cancers in adults, but data on pediatric tumors are scarce. Because, by immunohistochemistry, HIF-1alpha expression was readily detectable in 18 of 28 primary Ewing's sarcoma family tumors (ESFT), a group of highly malignant bone-associated tumors in children and young adults, we studied the effect of hypoxia on ESFT cell lines in vitro. Intriguingly, we found that EWS-FLI1 protein expression, which characterizes ESFT, is upregulated by hypoxia in a HIF-1alpha-dependent manner. Hypoxia modulated the EWS-FLI1 transcriptional signature relative to normoxic conditions. Both synergistic as well as antagonistic transcriptional effects of EWS-FLI1 and of hypoxia were observed. Consistent with alterations in the expression of metastasis-related genes, hypoxia stimulated the invasiveness and soft agar colony formation of ESFT cells in vitro. Our data represent the first transcriptome analysis of hypoxic ESFT cells and identify hypoxia as an important microenvironmental factor modulating EWS-FLI1 expression and target gene activity with far-reaching consequences for the malignant properties of ESFT.
Aryee
Dave N T
DN
Children's Cancer Research Institute, St. Anna Kinderkrebsforschung, Vienna, Austria. dave.aryee@ccri.at
Niedan
Stephan
S
Kauer
Maximilian
M
Schwentner
Raphaela
R
Bennani-Baiti
Idriss M
IM
Ban
Jozef
J
Muehlbacher
Karin
K
Kreppel
Michael
M
Walker
Robert L
RL
Meltzer
Paul
P
Poremba
Christopher
C
Kofler
Reinhard
R
Kovar
Heinrich
H
D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D001859:Bone Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D053263:Gene Regulatory Networks; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D007124:Immunoenzyme Techniques; D020411:Oligonucleotide Array Sequence Analysis; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D051789:Proto-Oncogene Protein c-fli-1 / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034802:RNA-Binding Protein EWS; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012512:Sarcoma, Ewing / Q000235:genetics* / Q000473:pathology; D015533:Transcriptional Activation
D014408:Biomarkers, Tumor; C106031:EWS-FLI fusion protein; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D012333:RNA, Messenger; D034802:RNA-Binding Protein EWS