Hasan, TanwirCaragher, Seamus P.Shireman, Jack M.Park, Cheol H.Atashi, FatemehBaisiwala, ShivaniLee, GinaGuo, DonnaWang, Jennifer Y.Dey, MahuaWu, MeijingLesniak, Maciej S.Horbinski, Craig M.James, C. DavidAhmed, Atique U.2019-08-022019-08-022019-03-29Hasan, T., Caragher, S. P., Shireman, J. M., Park, C. H., Atashi, F., Baisiwala, S., … Ahmed, A. U. (2019). Interleukin-8/CXCR2 signaling regulates therapy-induced plasticity and enhances tumorigenicity in glioblastoma. Cell death & disease, 10(4), 292. doi:10.1038/s41419-019-1387-6https://hdl.handle.net/1805/20161Emerging evidence reveals enrichment of glioma-initiating cells (GICs) following therapeutic intervention. One factor known to contribute to this enrichment is cellular plasticity-the ability of glioma cells to attain multiple phenotypes. To elucidate the molecular mechanisms governing therapy-induced cellular plasticity, we performed genome-wide chromatin immunoprecipitation sequencing (ChIP-Seq) and gene expression analysis (gene microarray analysis) during treatment with standard of care temozolomide (TMZ) chemotherapy. Analysis revealed significant enhancement of open-chromatin marks in known astrocytic enhancers for interleukin-8 (IL-8) loci as well as elevated expression during anti-glioma chemotherapy. The Cancer Genome Atlas and Ivy Glioblastoma Atlas Project data demonstrated that IL-8 transcript expression is negatively correlated with GBM patient survival (p = 0.001) and positively correlated with that of genes associated with the GIC phenotypes, such as KLF4, c-Myc, and HIF2α (p < 0.001). Immunohistochemical analysis of patient samples demonstrated elevated IL-8 expression in about 60% of recurrent GBM tumors relative to matched primary tumors and this expression also positively correlates with time to recurrence. Exposure to IL-8 significantly enhanced the self-renewing capacity of PDX GBM (average threefold, p < 0.0005), as well as increasing the expression of GIC markers in the CXCR2 population. Furthermore, IL-8 knockdown significantly delayed PDX GBM tumor growth in vivo (p < 0.0005). Finally, guided by in silico analysis of TCGA data, we examined the effect of therapy-induced IL-8 expression on the epigenomic landscape of GBM cells and observed increased trimethylation of H3K9 and H3K27. Our results show that autocrine IL-8 alters cellular plasticity and mediates alterations in histone status. These findings suggest that IL-8 signaling participates in regulating GBM adaptation to therapeutic stress and therefore represents a promising target for combination with conventional chemotherapy in order to limit GBM recurrence.en-USAttribution-NonCommercial-NoDerivs 3.0 United StatesGlioma-initiating cells (GICs)Therapy-induced cellular plasticityCancer Genome AtlasIvy Glioblastoma Atlas ProjectArticle