Project description:High levels of LMO1 expression synergizes with MYCN to accelerate neuroblastomagenesis, enhance disease penetrance and promote widespread metastasis in zebrafish. Transcriptomic analysis of human neuroblasotma cells with programed expression of LMO1 vs vector control or neuroblastoma cells with differential endogenous LMO1 expression revealed that gene signitures affecting tumor cell-extracellular matrix interaction are significantly associated with high levels of LMO1 expression. Our findings provide compelling evidence for a major pathogenic role of LMO1 in MYCN-driven neuroblastoma.
Project description:Neuroblastoma is an embryonal tumor of the peripheral sympathetic nervous system. Elevated expression of the transcription factor LMO1 and the polymorphisms within this gene are associated with the susceptibility to develop neuroblastoma. LMO1 has been implicated as an oncogene in T-cell acute lymphoblastic leukemia; however, the transcriptional targets regulated by this protein in neuroblastoma cells are unknown. Here, we identify the genes and molecular pathways controlled by LMO1 in neuroblastoma cells. ChIP-seq analysis revealed that LMO1-bound regions are frequently co-occupied by GATA3 and MYCN proteins and are associated with active histone marks in neuroblastoma cells. RNA-seq analysis demonstrated that LMO1 regulates gene expression in a tumor type-specific manner. One high-confidence target gene directly regulated by LMO1 and MYCN is ASCL1, which is more highly expressed in adrenergic subtype of neuroblastoma cells as compared to normal neuronal cells. High levels of ASCL1 expression are associated with inferior overall survival in primary human neuroblastoma cases. ChIP-seq analysis identified a regulatory element controlling ASCL1 expression that is bound by LMO1, MYCN and the members of the core regulatory circuitry in neuroblastoma cells. Furthermore, ASCL1 is required for neuroblastoma cell growth and regulates genes responsible for repression of neuronal cell differentiation. Taken together, our results implicate ASCL1 as a critical downstream target of LMO1 in the molecular pathogenesis of neuroblastoma.
Project description:Childhood neuroblastomas exhibit plasticity between an undifferentiated neural crest-like “mesenchymal” cell state and a more differentiated sympathetic “adrenergic” cell state. These cell states are governed by autoregulatory transcriptional loops called core regulatory circuitries (CRCs), which drive the early development of sympathetic neuronal progenitors from migratory neural crest cells during embryogenesis. The adrenergic cell identity of neuroblastoma requires LMO1 as a transcriptional co-factor. Both LMO1 expression levels and the risk of developing neuroblastoma in children are associated with a single nucleotide polymorphism G/T that affects a GATA motif in the first intron of LMO1. Here we showed that wild-type zebrafish with the GATA genotype developed adrenergic neuroblastoma, while knock-in of the protective TATA allele at this locus reduced the penetrance of MYCN-driven tumors, which were restricted to the mesenchymal cell state. Whole genome sequencing of childhood neuroblastomas demonstrated that TATA/TATA tumors also exhibited a mesenchymal cell state and were low risk at diagnosis. Thus, conversion of the regulatory GATA to a TATA allele in the first intron of LMO1 reduced the neuroblastoma initiation rate by preventing formation of the adrenergic cell state, a mechanism that was conserved over 400 million years of evolution separating zebrafish and humans.
Project description:To dissect molecular pathways regulated by LMO1 in neuroblastoma, we performed microarray gene expression profiling in a neuroblastoma cells (SHSY-5Y) after LMO1 knockdown.
Project description:MYCN amplification (MNA) is a defining feature of high-risk neuroblastoma (NB) that predicts poor prognosis. However, whether genes within or in close proximity to the MYCN amplicon also contribute to aggressiveness in MNA+ NB remains poorly understood. Here we identify that GREB1, a transcription factor encoding gene neighboring the MYCN locus, is frequently co-expressed with MYCN, and promotes cell survival in MNA+ NB. GREB1 controls gene expression independently of MYCN in MNA+ NB, among which we uncover Myosin 1B (MYO1B) as being highly expressed in MNA+ NB. MYO1B promotes aggressive features, including invasive capacity in vitro, as well as extravasation and distant metastasis in vivo. Global secretome and proteome profiling further delineate MYO1B as a major regulator of secretome reprogramming in MNA+ NB cells. Moreover, we identify the cytokine MIF as an important pro-invasive and pro-metastatic mediator of MYO1B activity. Together, we have identified a putative GREB1-MYO1B-MIF axis as an unconventional mechanism that promotes the aggressiveness of MNA+ NB, and independently of MYCN. Furthermore, we find that MYO1B is upregulated in association with other oncoproteins during cellular transformation, and is dramatically increased in multiple human cancer types, suggesting a crucial role of MYO1B in cancers in addition to MNA+ NB.
Project description:Neuroblastoma is an embryonic tumor arising from immature sympathetic nervous system progenitor cells. MYCN and ALK are driver oncogenes both of which are specifically expressed during early neurogenesis. This is in line with the assumption that neuroblastoma arises through disruption of normal developmental processes. MYCN has a broad impact on the tumor phenotype; however, the details of the MYCN driven oncogenic program are far from clear. In order to gain further insight into the role of gene expression during neuroblastoma initiation and progression, we evaluated gene expression profiles of hyperplastic ganglia and tumors isolated from MYCN transgenic mice.