Abstract 3892: Delineating the role of ZEB1 loss in the chemo and radioresistance of glioma stem cells

Abstract

Abstract The most prevalent brain cancer, Glioblastoma Multiforme (GBM) has an average survival of less than 2 years. Despite advances in therapy there is still an overall poor response to treatment which has been attributed to glioma stem cells (GSC’s), a subset of tumor cells that are able to self-renew, inhibit differentiation and are often chemo and radioresistant. The genetics and mechanisms underlying how glioma stem cells are able to repopulate tumors and affect patient survival desperately need to be defined. We are interested in delineating the role that ZEB1 (zinc finger e-box binding homeobox-1) loss has on GSC’s and what role this loss plays in the chemo and radioresistance of GSC’s. Most insights into ZEB1 regard it as tumorigenic and an initiator of EMT (epithelial mesenchymal transition). Surprisingly, in this study, we have shown that in TCGA datasets ZEB1 deletion frequently occurs and this loss actually results in poorer glioma patient survival. Copy number analysis as well as immunohistochemistry on patient samples shows that ZEB1 loss occurs both at the gene and protein level. Stable ZEB1 knockdown in our patient derived glioma stem cell lines results in increased proliferation and a resistance to differentiation. Following chemotherapy as well as radiotherapy, knockdown cell lines show increased cell viability as well as higher levels of secondary neurosphere formation. Decreased apoptosis and changes in cell cycle as well as the DNA damage response pathway were also observed in the knockdown lines following chemo and radiotherapy. Overall, this data indicates that loss of ZEB1 in GSC’s results in enhanced resistance to standard therapy. With these results, we have reason to believe that ZEB1 may be used as a novel therapeutic target to combat the chemo and radioresistance of glioma stem cells. Citation Format: Mecca Madany, Lincoln Edwards, John S. Yu. Delineating the role of ZEB1 loss in the chemo and radioresistance of glioma stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3892. doi:10.1158/1538-7445.AM2017-3892