ABSTRACT
EWS-FLI1 constitutes an oncogenic transcription factor that plays key roles in Ewing sarcoma development and maintenance. We have recently succeeded in generating an ex vivo mouse model for Ewing sarcoma by introducing EWS-FLI1 into embryonic osteochondrogenic progenitors. The model well recapitulates the biological characteristics, small round cell morphology, and gene expression profiles of human Ewing sarcoma. Here, we clarified the global DNA binding properties of EWS-FLI1 in mouse Ewing sarcoma. GGAA microsatellites were found to serve as binding sites of EWS-FLI1 albeit with less frequency than that in human Ewing sarcoma; moreover, genomic distribution was not conserved between human and mouse. Nevertheless, EWS-FLI1 binding sites within GGAA microsatellites were frequently associated with the histone H3K27Ac enhancer mark, suggesting that EWS-FLI1 could affect global gene expression by binding its target sites. In particular, the Fox transcription factor binding motif was frequently observed within EWS-FLI1 peaks and Foxq1 was identified as the cooperative partner that interacts with the EWS portion of EWS-FLI1. Trib1 and Nrg1 were demonstrated as target genes that are co-regulated by EWS-FLI1 and Foxq1, and are important for cell proliferation and survival of Ewing sarcoma. Collectively, our findings present novel aspects of EWS-FLI1 function as well as the importance of GGAA microsatellites.
Subject(s)
Forkhead Transcription Factors/metabolism , Gene Expression Regulation, Neoplastic/genetics , Microsatellite Repeats/genetics , Oncogene Proteins, Fusion/metabolism , Proto-Oncogene Protein c-fli-1/metabolism , RNA-Binding Protein EWS/metabolism , Sarcoma, Ewing/pathology , Animals , Apoptosis/genetics , Binding Sites/genetics , Cell Cycle/genetics , Cell Line, Tumor , Cell Proliferation/genetics , Chondrogenesis/genetics , DNA-Binding Proteins/metabolism , Disease Models, Animal , Embryonic Stem Cells/cytology , Epithelial-Mesenchymal Transition/genetics , Forkhead Transcription Factors/genetics , Histones/metabolism , Humans , Intracellular Signaling Peptides and Proteins/genetics , Mice , Neuregulin-1/genetics , Oncogene Proteins, Fusion/genetics , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein Serine-Threonine Kinases/genetics , Proto-Oncogene Protein c-fli-1/genetics , RNA Interference , RNA, Small Interfering/genetics , RNA-Binding Protein EWS/genetics , Sarcoma, Ewing/geneticsABSTRACT
Alveolar soft part sarcoma (ASPS) is a slowly growing, but highly metastatic, sarcoma that affects adolescents and young adults. Its characteristic alveolar structure is constituted by tumor cell nests and an abundant vascular network that is responsible for metastatic activities at the initial stage. Here, we have generated a new ex vivo mouse model for ASPS that well recapitulates associated angiogenic and metastatic phenotypes. In mouse ASPS, the tumor cells frequently showed tumor intravasation, with the intravascular tumor cells presenting as organoid structures covered with hemangiopericytes, which is also observed in human ASPS. High expression of glycoprotein nmb (GPNMB), a transcriptional target of ASPSCR1-TFE3, was observed at the sites of intravasation. ASPS tumor cells also demonstrated enhanced transendothelial migration activity, which was inhibited by silencing of Gpnmb, indicating that GPNMB plays an important role in tumor intravasation, a key step in cancer metastasis. The present model also enabled the evaluation of TFE/MITF family transcription factor function, which demonstrated that ASPSCR1-TFEB possessed definitive albeit less marked oncogenic activity than that of ASPSCR1-TFE3. Collectively, our mouse model provides a tool to understand oncogenic, angiogenic, and metastatic mechanisms of ASPS. It also identifies important motifs within the ASPSCR1-TFE3 fusion protein and provides a platform for developing novel therapeutic strategies for this disorder. Cancer Res; 77(4); 897-907. ©2016 AACR.
Subject(s)
Neoplasm Metastasis , Sarcoma, Alveolar Soft Part/pathology , Animals , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/physiology , Carrier Proteins/genetics , Carrier Proteins/physiology , Cell Movement , Eye Proteins/physiology , Humans , Intracellular Signaling Peptides and Proteins , Membrane Glycoproteins/physiology , Mice , Mice, Inbred BALB C , Platelet Endothelial Cell Adhesion Molecule-1/analysisABSTRACT
Changes in facial bones may represent a manifestation of systemic disease. Dentists play an important role in the early detection of these manifestations of complex systemic diseases. A case of unusual maxillary mixed (osteoblastic and osteolytic) lesions as an initial manifestation of childhood acute myeloid leukemia (AML) is presented. A 12-year-old male patient was referred to the Department of Oral Medicine complaining of severe swelling in the right buccal region. 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) showed enhanced FDG uptake in the right maxillary sinus. In addition, PET maximum intensity projection image showed diffused FDG uptake in the entire bone marrow. Bone marrow aspiration was performed on the lumbar vertebra, and fluorescence in situ hybridization (FISH) demonstrated AML. The patient was diagnosed with AML (M5a) and treated with chemotherapy by the pediatric department. Six months later, the patient achieved complete remission. After chemotherapy, the disappearance of the osteoblastic and osteolytic lesion and 18F-FDG accumulation were confirmed by PET/CT. Dentists should be familiar with oral manifestations of leukemia because early detection of oral lesions would increase the life span of the patients and reduce the severity of complications.
