Dataset Information

C/EBP?-1 promotes transformation and chemoresistance in Ewing sarcoma cells.

ABSTRACT: CEBPB copy number gain in Ewing sarcoma was previously shown to be associated with worse clinical outcome compared to tumors with normal CEBPB copy number, although the mechanism was not characterized. We employed gene knockdown and rescue assays to explore the consequences of altered CEBPB gene expression in Ewing sarcoma cell lines. Knockdown of EWS-FLI1 expression led to a decrease in expression of all three C/EBP? isoforms while re-expression of EWS-FLI1 rescued C/EBP? expression. Overexpression of C/EBP?-1, the largest of the three C/EBP? isoforms, led to a significant increase in colony formation when cells were grown in soft agar compared to empty vector transduced cells. In addition, depletion of C/EBP? decreased colony formation, and re-expression of either C/EBP?-1 or C/EBP?-2 rescued the phenotype. We identified the cancer stem cell marker ALDH1A1 as a target of C/EBP? in Ewing sarcoma. Furthermore, increased expression of C/EBP? led to resistance to chemotherapeutic agents. In summary, we have identified CEBPB as an oncogene in Ewing sarcoma. Overexpression of C/EBP?-1 increases transformation, upregulates expression of the cancer stem cell marker ALDH1A1, and leads to chemoresistance.

SUBMITTER: Gardiner JD

PROVIDER: S-EPMC5432234 | biostudies-literature | 2017 Apr

REPOSITORIES: biostudies-literature

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Publications

C/EBPβ-1 promotes transformation and chemoresistance in Ewing sarcoma cells.

Gardiner Jamie D JD Abegglen Lisa M LM Huang Xiaomeng X Carter Bryce E BE Schackmann Elizabeth A EA Stucki Marcus M Paxton Christian N CN Lor Randall R R Amatruda James F JF Putnam Angelica R AR Kovar Heinrich H Lessnick Stephen L SL Schiffman Joshua D JD

Oncotarget 20170401 16

CEBPB copy number gain in Ewing sarcoma was previously shown to be associated with worse clinical outcome compared to tumors with normal CEBPB copy number, although the mechanism was not characterized. We employed gene knockdown and rescue assays to explore the consequences of altered CEBPB gene expression in Ewing sarcoma cell lines. Knockdown of EWS-FLI1 expression led to a decrease in expression of all three C/EBPβ isoforms while re-expression of EWS-FLI1 rescued C/EBPβ expression. Overexpres ...[more]

PMID: 28148901

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Project description:Sarcomas are highly aggressive cancers of mesenchymal origin whose clinical management is highly complex. This is partly due to a lack of understanding of the molecular mechanisms underpinning the transformation of mesenchymal stromal/stem cells (MSCs) which are presumed to be the sarcoma-initiating cells. c-Myc is amplified/overexpressed in a range of sarcomas where it has an established oncogenic role and there is evidence that it contributes to the malignant transformation of MSCs. T-box transcription factor 3 (TBX3) is upregulated by c-Myc in a host of sarcoma subtypes where it promotes proliferation, tumor formation, migration, and invasion. This study investigated whether TBX3 is a c-Myc target in human MSCs (hMSCs) and whether overexpressing TBX3 in hMSCs can phenocopy c-Myc overexpression to promote malignant transformation. Using siRNA, qRT-PCR, luciferase reporter and chromatin-immunoprecipitation assays, we show that c-Myc binds and directly activates TBX3 transcription in hMSCs at a conserved E-box motif. When hMSCs were engineered to stably overexpress TBX3 using lentiviral gene transfer and the resulting cells characterised in 2D and 3D, the overexpression of TBX3 was shown to promote self-renewal, bypass senescence, and enhance proliferation which corresponded with increased levels of cell cycle progression markers (cyclin A, cyclin B1, CDK2) and downregulation of the p14ARF/MDM2/p53 tumor suppressor pathway. Furthermore, TBX3 promoted the migratory and invasive ability of hMSCs which associated with increased levels of markers of migration (Vimentin, SLUG, SNAIL, TWIST1) and invasion (MMP2, MMP9). Transcriptomic analysis revealed that genes upregulated upon TBX3 overexpression overlapped with c-myc targets, were involved in cell cycle progression, and were associated with sarcomagenesis. Together, the data described indicate that the c-Myc/TBX3 oncogenic molecular pathway may be a key mechanism that transforms hMSCs into sarcomas.

Dataset Information

C/EBP?-1 promotes transformation and chemoresistance in Ewing sarcoma cells.

Publications

C/EBPβ-1 promotes transformation and chemoresistance in Ewing sarcoma cells.

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