G-protein coupled receptor and RhoA mediated transcriptional response in astroglial inflammation and glioblastoma tumor formation
Glioblastoma multiforme (GBM), the most common and aggressive form of brain tumor, is associated with known driver mutations but targeting these has proven ineffective thus GBM is one of the most lethal human cancers. Our past research has provided considerable insight into the signals elicited through the S1P and PAR1 receptors, G-protein coupled receptors (GPCRs) that activate RhoA to increase cell proliferation, survival, and invasion of astrocytes and 1321N1 glioblastoma cells. Our recent studies demonstrate robust activation of the transcriptional co-activators MRTF-A and YAP through RhoA signaling in glioblastoma cells, and implicate altered gene expression in proliferative and migratory responses to GPCR agonists. The objective of this project is to demonstrate that robust transcriptional gene programs elicited through RhoA signaling are critical to glioblastoma multiforme (GBM) tumor growth and maintenance of glioblastoma stem cells (GSC), with a long term goal of identifying new therapeutic targets for this devastating disease. A subset of studies use the human 1321N1 glioblastoma cells in which MRTF-A or YAP or their target genes are
deleted to define their role in proliferation, survival, adhesion, migration, invasion and angiogenesis. Other studies use patient-derived glioblastoma xenografts (PDX), a model of glioblastoma stem cells, for in vitro analysis and in vivo growth as orthotopic (brain) xenografts, testing dependence on YAP, MRTF-A, GPCRs that activate RhoA and their downstream target genes. An additional approach examines the effects of oncogenic Ras on mouse astrocytes in which molecules in the RhoA signaling pathway are genetically deleted, along with in vivo studies of gliomagenesis in response to lentiviral delivery of the Ras oncogene into the hippocampus of WT mice and those in which RhoA signaling pathways are inhibited. If RhoA signaling contributes to tumor growth, invasion, and changes in expression of target genes and stem cell markers, this finding could shift the focus of current research and clinical practice from the established disease drivers towards consideration of GPCR- and RhoA-regulated signaling pathways in GBM.
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Yu, OM., Miyamoto, S., Brown, J.H., MRTF-A and YAP exert dual control in GPCR and RhoA-mediated transcriptional regulation and cell proliferation, Mol Cell Biol.; 36(1):39-49, 2016. F1000 Prime Recommended
Yu O.M., Benitez J.A., Plouffe S. W., Ryback D., Klein A., Smith J., Greenbaum J., Delatte B., Rao A., Guan K.L., Furnari F.B., Chaim O.M., Miyamoto S., Brown, J.H. YAP and MRTF-A, transcriptional co-activators of RhoA-mediated gene expression, are critical for glioblastoma tumorigenicity. Oncogene. 2018. Jun 11. doi: 10.1038/s41388-018-0301-5. F1000 Prime Recommended