Search

Consensus NMF of 81 primary ependymoma samples at k = 3 delineates two posterior fossa subgroups in the study cohort.

Supplemental Figure Legends

STAT3, IL-6 and inflammatory response pathway signaling associated gene expression is upregulated in Group A EPN.

Experimentally determined STAT3 upregulated genes.

Ependymoma (EPN) in childhood is a brain tumor with substantial mortality. Inflammatory response has been identified as a molecular signature of high-risk Group A EPN. To better understand the biology of this phenotype and aid therapeutic development, transcriptomic data from Group A and B EPN patient tumor samples, and additional malignant and normal brain data, were analyzed to identify the mechanism underlying EPN Group A inflammation. Enrichment of IL6 and STAT3 pathway genes were found to distinguish Group A EPN from Group B EPN and other brain tumors, implicating an IL6 activation of STAT3 mechanism. EPN tumor cell growth was shown to be dependent on STAT3 activity, as demonstrated using shRNA knockdown and pharmacologic inhibition of STAT3 that blocked proliferation and induced apoptosis. The inflammatory factors secreted by EPN tumor cells were shown to reprogram myeloid cells, and this paracrine effect was characterized by a significant increase in pSTAT3 and IL8 secretion. Myeloid polarization was shown to be dependent on tumor secretion of IL6, and these effects could be reversed using IL6-neutralizing antibody or IL6 receptor–targeted therapeutic antibody tocilizumab. Polarized myeloid cell production of IL8 drove unpolarized myeloid cells to upregulate CD163 and to produce a number of proinflammatory cytokines. Collectively, these findings indicate that constitutive IL6/STAT3 pathway activation is important in driving tumor growth and inflammatory cross-talk with myeloid cells within the Group A EPN microenvironment. Effective design of Group A–targeted therapy for children with EPN may require reversal of this potentially immunosuppressive and protumor pathway. Cancer Immunol Res; 3(10); 1165–74. ©2015 AACR.

IL-6 is the driving cytokine for immune suppressive phenotype observed in 811 CM monocytes.

S3I-201 effects on cell cycle EPN cell line 811 and apoptosis in EPN cell line 723.

Ratio of Group A EPN IL6/STAT3 pathway genes in tumor versus the myeloid compartments.