title: Inhibition of Notch3 signalling induces rhabdomyosarcoma cell differentiation promoting p38 phosphorylation and p21(Cip1) expression and hampers tumour cell growth in vitro and in vivo.
abstract: Rhabdomyosarcoma (RMS) is a paediatric soft-tissue sarcoma arising from skeletal muscle precursors coexpressing markers of proliferation and differentiation. Inducers of myogenic differentiation suppress RMS tumourigenic phenotype. The Notch target gene HES1 is upregulated in RMS and prevents tumour cell differentiation in a Notch-dependent manner. However, Notch receptors regulating this phenomenon are unknown. In agreement with data in RMS primary tumours, we show here that the Notch3 receptor is overexpressed in RMS cell lines versus normal myoblasts. Notch3-targeted downregulation in RMS cells induces hyper-phosphorylation of p38 and Akt essential for myogenesis, resulting in the differentiation of tumour cells into multinucleated myotubes expressing Myosin Heavy Chain. These phenomena are associated to a marked decrease in HES1 expression, an increase in p21(Cip1) level and the accumulation of RMS cells in the G1 phase. HES1-forced overexpression in RMS cells reverses, at least in part, the pro-differentiative effects of Notch3 downregulation. Notch3 depletion also reduces the tumourigenic potential of RMS cells both in vitro and in vivo. These results indicate that downregulation of Notch3 is sufficient to force RMS cells into completing a correct full myogenic program providing evidence that it contributes, partially through HES1 sustained expression, to their malignant phenotype. Moreover, they suggest Notch3 as a novel potential target in human RMS.
authors: Department of Oncohematology, Ospedale Pediatrico Bambino Gesù, IRCCS, Roma, Italy.
authors: L
authors: L
authors: Raimondi
authors: R
authors: R
authors: Ciarapica
authors: M
authors: M
authors: De Salvo
authors: F
authors: F
authors: Verginelli
authors: M
authors: M
authors: Gueguen
authors: C
authors: C
authors: Martini
authors: L
authors: L
authors: De Sio
authors: G
authors: G
authors: Cortese
authors: M
authors: M
authors: Locatelli
authors: T P
authors: TP
authors: Dang
authors: N
authors: N
authors: Carlesso
authors: L
authors: L
authors: Miele
authors: S
authors: S
authors: Stifani
authors: I
authors: I
authors: Limon
authors: F
authors: F
authors: Locatelli
authors: R
authors: R
authors: Rota
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010766:Phosphorylation / Q000235:genetics / Q000502:physiology; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D000071656:Receptor, Notch3; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D012208:Rhabdomyosarcoma / Q000235:genetics / Q000378:metabolism* / Q000628:therapy; D015398:Signal Transduction; D023041:Xenograft Model Antitumor Assays; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C499374:NOTCH3 protein, human; D000071656:Receptor, Notch3; D051880:Receptors, Notch; D048051:p38 Mitogen-Activated Protein Kinases