While cancer has traditionally been viewed as a disease process based on genetic aberrations, there is increasing evidence that epigenetic alterations play an important role in the pathogenesis and progression of many types of cancer. One emerging epigenetic driver of cancer is the super-enhancer, which is defined as a series of traditional enhancers in close physical proximity that determine cell state and cell identity. Super- enhancers define cell state, are associated with genes that control cell type specific biology, and are enriched for disease-associated genetic variation. Super-enhancers identified from cancer cells identify tumor- associated genes in glioblastoma, small cell lung cancer, and multiple myeloma. Because of the close association between super-enhancer structure and biological function, study of the alterations in disease- specific super-enhancers may reveal insights into the molecular mechanisms of disease pathogenesis. Glioblastoma is the most common and most aggressive primary brain tumor, with poor responses to all therapeutic modalities despite intensive research. One major contributor to the poor prognosis of glioblastoma is the presence of cancer stem cells. These self-renewing tumor cells play a role in resistance to radiation and chemotherapy, as well as maintenance of tumor heterogeneity and angiogenesis. Because of these features, cancer stem cells have become an important target for the design of novel therapeutic strategies. To better understand key regulators of glioma stem cell identity, an original super-enhancer screen identified genes that are epigenetically upregulated in glioma stem cells and for which elevated expression is associated with poor patient prognosis. This approach revealed lipid metabolism pathways and specifically the gene ELOVL2, which is a lead candidate for further evaluation. Cancer cells utilize aberrant metabolic processes to drive increased proliferation and altered signaling. While lipid metabolism has been implicated in the process of oncogenesis, the precise functions of ELOVL2 have not been defined in cancer.
The first aim will define the role of ELOVL2 in glioma cell survival, self-renewal capacity, and tumor formation in both in vitro and in vivo settings.
The second aim will investigate the transcription factor network that regulates the expression of ELOVL2 including enhancer elements, transcription factor occupancy, and super-enhancer structure. These approaches will lead to a greater understanding of the epigenetic features that define the glioma stem cell state and inform the development of novel therapeutics.
Glioblastoma is a lethal brain cancer for which there are currently no successful therapeutic options. Because cancer stem cells are proposed to underlie resistance to traditional treatment options, this proposal seeks to evaluate novel epigenetically regulated genes, which promote survival and self-renewal of cancer stem cells. This endeavor will inform future drug development by delivering the next generation of glioblastoma stem cell specific targets.
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