Project description:Epigenetic modifications have been shown to be important in developmental tumors as Ewing sarcoma. We profiled the DNA methylation status of 15 primary tumors and 7 cell lines using the Infinium Human Methylation 450k. Differential methylation analysis between Ewing sarcoma and reference samples revealed 1,166 hypermethylated and 864 hypomethylated CpG sites (Bonferroni p<0.05, δ-β-value with absolute difference of >0.20) corresponding to 392 and 470 genes respectively. Gene Ontology analysis of genes differentially methylated in Ewing sarcoma samples showed a significant enrichment of developmental genes. Membrane and cell signal genes were also enriched, among those, 11 were related to caveola formation. We identified differential hypermethylation of CpGs located in the body and S-Shore of the PTRF gene in Ewing sarcoma that correlated with its repressed transcriptional state. Reintroduction of PTRF/Cavin-1 in Ewing sarcoma cells revealed a role of this protein as a tumor suppressor. Restoration of caveolae in the membrane of Ewing sarcoma cells, by exogenously reintroducing PTRF, disrupts the MDM2/p53 complex, which consequently results in the activation of p53 and the induction of apoptosis.
Project description:Ewing sarcoma is an aggressive pediatric small round cell tumor that predominantly occurs in bone. Approximately 85% of Ewing sarcomas harbor the EWS/FLI fusion protein, which arises from a chromosomal translocation, t(11:22)(q24:q12). EWS/FLI interacts with numerous lineage-essential transcription factors to maintain mesenchymal progenitors in an undifferentiated state. We previously showed that EWS/FLI binds the osteogenic transcription factor RUNX2 and prevents osteoblast differentiation. In this study, we investigated the role of another Runt-domain protein, RUNX3, in Ewing sarcoma. RUNX3 participates in mesenchymal-derived bone formation and is a context dependent tumor suppressor and oncogene. RUNX3 was detected in all Ewing sarcoma cells examined, whereas RUNX2 was detected in only 73% of specimens. Like RUNX2, RUNX3 binds to EWS/FLI via its Runt domain. EWS/FLI prevented RUNX3 from activating the transcription of a RUNX-responsive reporter, p6OSE2. Stable suppression of RUNX3 expression in the Ewing sarcoma cell line A673 delayed colony growth in anchorage independent soft agar assays and reversed expression of EWS/FLI-responsive genes. These results demonstrate an important role for RUNX3 in Ewing sarcoma. RNA-seq to compare transcriptiome of control A673 ewing sarcoma cells stably expression a non-target or RUNX3 shRNA
Project description:Caveolae are specialized domains of the plasma membrane. Formation of these invaginations is dependent on the expression of Caveolin-1 or -3 and proteins of the cavin family. In response to stress, caveolae disassemble and cavins are released from caveolae, allowing cavins to potentially interact with intracellular targets. Here, we describe the intracellular (non-plasma membrane) cavin interactome using biotin affinity proteomics and mass spectrometry. We validate 47 potential cavin-interactor proteins using a cell-free expression system and protein-protein binding assays. These data, together with pathway analyses, revealed novel roles for cavin proteins in metabolism and stress signaling. We validated the interaction between one candidate interactor protein, protein phosphatase 1 alpha (PP1α), and Cavin-1 and -3 and show that UV treatment causes release of Cavin3 from caveolae allowing interaction with, and inhibition of, PP1α. This interaction increases H2AX phosphorylation to stimulate apoptosis, identifying a pro-apoptotic signaling pathway from surface caveolae to the nucleus.
Project description:Caveolae are specialized domains of the plasma membrane. Formation of these invaginations is dependent on the expression of Caveolin-1 or -3 and proteins of the cavin family. In response to stress, caveolae disassemble and cavins are released from caveolae, allowing cavins to potentially interact with intracellular targets. Here, we describe the intracellular (non-plasma membrane) cavin interactome using biotin affinity proteomics and mass spectrometry. We validate 47 potential cavin-interactor proteins using a cell-free expression system and protein-protein binding assays. These data, together with pathway analyses, revealed novel roles for cavin proteins in metabolism and stress signaling. We validated the interaction between one candidate interactor protein, protein phosphatase 1 alpha (PP1α), and Cavin-1 and -3 and show that UV treatment causes release of Cavin3 from caveolae allowing interaction with, and inhibition of, PP1α. This interaction increases H2AX phosphorylation to stimulate apoptosis, identifying a pro-apoptotic signaling pathway from surface caveolae to the nucleus.
Project description:In this study we show that lysyl oxidase (LOX), an enzyme involved in maintaining structural integrity of the extracellular matrix, is expressed at low levels in Ewing sarcoma cells and primary tumors and is downregulated by the EWS/FLI1 oncoprotein characteristic of these tumors. Using a doxycycline inducible system to restore LOX expression in an Ewing sarcoma derived cell line, we show that LOX displays tumor suppressor activities. Interestingly, we show that the tumor suppressor activity resides in the propeptide domain of LOX (LOX-PP), an N-terminal domain produced by proteolytic cleavage during the physiological processing of LOX. Finally, we show that LOX-PP inhibits ERK/MAPK signalling pathway, and that many pathways involved in cell cycle progression were significant deregulated by LOX-PP, providing a mechanistic explanation to the cell proliferation inhibition observed upon LOX-PP expression. In summary, our observations indicate that deregulation of the LOX gene participates in Ewing sarcoma development and identify LOX-PP as a new therapeutic target for one of the most aggressive paediatric malignancies. These findings suggest that therapeutic strategies based in the administration of LOX propeptide or functional analogues could be useful in the treatment of this devastating paediatric cancer. A673 cells derived from Ewing sarcoma were genetically enginereed to express LOX-PP upon doxycycline stimulation (72 hours). Three independent experiments from control cells and three independent experiments from A673 cells expressing LOX-PP were done. Gene expression profile in A673 cells expressing LOX-PP vs control cells were compared.
Project description:Though p53 mutations are rare in Ewing sarcoma, there is a strong indication that p53-mutant tumors form a particularly bad prognosis group. As such, novel treatment strategies are warranted that would specifically target and eradicate tumor cells containing mutant-p53 in this subset of ES patients. PRIMA-1Met/APR-246 is a small organic molecule which has been shown to restore tumor suppressor function primarily to mutant p53 and to also induce cell death in various cancer cell types. We analyzed the apoptosis inducibility on Ewing sarcoma cells harbouring different p53 mutations upon exposure to APR-246. Gene expression profiles of three STA-ET-7 cell lines established from the same patient at different stages of the disease was assessed by microarray analysis as these cell lines responded variably to APR-246.
Project description:We identify and validate an Ewing sarcoma-specific CRC, which is under control of EWS-FLI1. Formed by KLF15, TCF4 and NKX2-2, this CRC apparatus coordinates the gene expression programs in Ewing sarcoma cells. These data advance the understanding of the mechanistic basis of transactional dysregulation in Ewing sarcoma, and provide potential novel therapeutic strategies against this malignancy.