ABSTRACT
Rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children and young adults, is characterized by a partially differentiated myogenic phenotype. We have previously shown that the blocking of tumor growth and resumption of differentiation can be achieved by re-expression of miR-206, a muscle-enriched microRNA missing in RMS. In this work, we focused on BAF53a, one of the genes downregulated in miR-206-expressing RMS cells, which codes for a subunit of the SWI/SNF chromatin remodeling complex. Here we show that the BAF53a transcript is significantly higher in primary RMS tumors than in normal muscle, and is a direct target of miR-206. Sustained expression of BAF53a interferes with differentiation in myogenic cells, whereas its silencing in RMS cells increases expression of myogenic markers and inhibits proliferation and anchorage-independent growth. Accordingly, BAF53a silencing also impairs embryonal RMS and alveolar RMS tumor growth, inducing their morphological and biochemical differentiation. These results indicate that failure to downregulate the BAF53a subunit may contribute to the pathogenesis of RMS, and suggest that BAF53a may represent a novel therapeutic target for this tumor.
Subject(s)
Actins/genetics , Chromosomal Proteins, Non-Histone/genetics , Chromosomal Proteins, Non-Histone/metabolism , DNA-Binding Proteins/genetics , Gene Expression Regulation, Neoplastic , MicroRNAs/metabolism , Muscle Neoplasms/pathology , Rhabdomyosarcoma/pathology , Transcription Factors/metabolism , Cell Line, Tumor , Cell Proliferation , Cell Transformation, Neoplastic/genetics , Down-Regulation , Fibroblasts/metabolism , Fibroblasts/pathology , Humans , Muscle Development/genetics , Muscle Neoplasms/genetics , MyoD Protein/metabolism , Rhabdomyosarcoma/genetics , Satellite Cells, Skeletal Muscle/metabolism , Satellite Cells, Skeletal Muscle/pathologySubject(s)
Amelogenin/genetics , DNA Primers/genetics , Gene Amplification , Mutation/physiology , Polymerase Chain Reaction/methods , Base Pair Mismatch/genetics , Base Pair Mismatch/physiology , Base Sequence , Binding Sites/genetics , Diagnostic Errors , False Negative Reactions , Female , Gene Amplification/physiology , Humans , Male , Pregnancy , Prenatal Diagnosis/methods , Sex Determination ProcessesABSTRACT
NF-kB is a transcription factor that mediates antiapoptotic signals in several cancer cell lines. Here we have demonstrated that the cytotoxic drug, Etoposide, activates NF-kB in K562, a chronic myeloid leukemia blast crisis cell line. Treatment with the NF-kB inhibitors MG-132, Bay11-7082, and Resveratrol impedes Etoposide-induced NF-kB activation, rendering K562 sensitive to Etoposide-induced apoptosis. Stable expression of mutant form of IkB-alpha, which retains NF-kB inactive in the cytoplasm of cells, confirmed the data obtained with molecular inhibitors. Both inhibitors and stable expression of SR-IkB are associated with down-modulation of the antiapoptotic protein Bcl-xL, suggesting that the survival pathway activated by Etoposide involves NF-kB-mediated Bcl-xL expression.
