Unknown,Transcriptomics,Genomics,Proteomics

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Aberrant DNA methylation in rhabdomyosarcoma

ABSTRACT: Many pediatric malignancies are embryonal in nature, and one hypothesis for the origin of embryonal tumors is that they arise from a defect in differentiation, either by an inability to terminally differentiate or a reversion to a pluripotent state. There is emerging evidence that epigenetic regulation plays an important role in the transition from embryonic stem cell to a more committed cell fate, utilizing both de novo DNA methylation and poised M-bM-^@M-^XbivalentM-bM-^@M-^Y chromatin domains (H3K27me3 and H3K4me3) to abolish pluripotency and gain lineage- and cell-type-specific characteristics as a cell differentiates. Thus inappropriate epigenetic silencing by aberrant DNA methylation of bivalent genes required for differentiation could lead to the uncontrolled cell growth observed in cancer. Our broad hypothesis is that aberrant DNA methylation in cancer is targeted to a non-random subset of critical pathways used in normal development. This dysregulation of the normal epigenetic program used in development promotes cellular proliferation and provides a mechanism to block differentiation in pediatric cancers, such as rhabdomyosarcoma. Examination of DNA methylation in fourteen human rhabdomyosarcoma patient samples using RRBS. In addition, RRBS was used to examine DNA methylation in one human rhabdomyosarcoma cell line (RD) forced to terminally differentiate by expression of the forced heterodimer MyoD~E12 (MDE). Lastly, RRBS was used to examine DNA methylation changes during normal differentiation in one primary human normal myoblast cell line

ORGANISM(S): Homo sapiens

SUBMITTER: Scott Diede

PROVIDER: E-GEOD-61150 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: Similar to replicating myoblasts, many rhabdomyosarcoma cells express the myogenic determination gene MyoD. In contrast to myoblasts, rhabdomyosarcoma cells do not make the transition from a regulative growth phase to terminal differentiation. Previously we demonstrated that the forced expression of MyoD with its E-protein dimerization partner was sufficient to induce differentiation and suppress multiple growth-promoting genes, suggesting that the dimer was targeting a switch that regulated the transition from growth to differentiation. Our data also suggested that a balance existed between various inhibitory transcription factors and MyoD activity that kept rhabdomyosarcomas trapped in a proliferative state. Methods: Potential myogenic co-factors identified by analysis of high-throughput sequencing of chromatin immunoprecipitation experiments in normal myogenic cells were tested for their ability to drive differentiation in rhabdomyosarcoma cell culture models, and their relation to MyoD activity determined through molecular biological experiments. Results: Modulation of the transcription factors RUNX1 and ZNF238, factors with poorly delineated roles in myogenic development, can induce differentiation in rhabdomyosarcoma cells and their activity is integrated, at least in part, through the activation of miR-206, which acts as a genetic switch to transition the cell from a proliferative growth phase to differentiation. The inhibitory transcription factor MSC also plays a role in controlling miR-206, appearing to function by occluding a binding site for MyoD in the miR-206 promoter. Conclusions: These findings suggest that nested feed-forward circuits that proceed from MyoD, to RUNX1, to ZNF238, and finally to miR-206 function in both rhabdomyosarcomas as well as normal myogenesis to control the decision point of proliferation versus differentiation. Two biologically independent sets of RD cells were transduced with either MD~E or empty vector pCLBabe retroviruses. After RNA extraction pairs of samples (MD~E versus pCLBabe) were hybridized to arrays, incorporating both dye-swap and technical replicates (i.e. 1 comparison x 2 dye-swaps x 2 biological replicates x 2 technical replicates = 8 arrays)

Project description:Background: Similar to replicating myoblasts, many rhabdomyosarcoma cells express the myogenic determination gene MyoD. In contrast to myoblasts, rhabdomyosarcoma cells do not make the transition from a regulative growth phase to terminal differentiation. Previously we demonstrated that the forced expression of MyoD with its E-protein dimerization partner was sufficient to induce differentiation and suppress multiple growth-promoting genes, suggesting that the dimer was targeting a switch that regulated the transition from growth to differentiation. Our data also suggested that a balance existed between various inhibitory transcription factors and MyoD activity that kept rhabdomyosarcomas trapped in a proliferative state. Methods: Potential myogenic co-factors identified by analysis of high-throughput sequencing of chromatin immunoprecipitation experiments in normal myogenic cells were tested for their ability to drive differentiation in rhabdomyosarcoma cell culture models, and their relation to MyoD activity determined through molecular biological experiments. Results: Modulation of the transcription factors RUNX1 and ZNF238, factors with poorly delineated roles in myogenic development, can induce differentiation in rhabdomyosarcoma cells and their activity is integrated, at least in part, through the activation of miR-206, which acts as a genetic switch to transition the cell from a proliferative growth phase to differentiation. The inhibitory transcription factor MSC also plays a role in controlling miR-206, appearing to function by occluding a binding site for MyoD in the miR-206 promoter. Conclusions: These findings suggest that nested feed-forward circuits that proceed from MyoD, to RUNX1, to ZNF238, and finally to miR-206 function in both rhabdomyosarcomas as well as normal myogenesis to control the decision point of proliferation versus differentiation. Total RNA samples were collected from human RD cells transduced with lentivirus carrying RUNX1, RP58 (ZNF238), miR-206 or GFP (three biological replicates each) and allowed to differentiate for 72 hours.

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Aberrant DNA methylation in rhabdomyosarcoma

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