ABSTRACT: Differential gene expression analysis of MYCN-amplified neuroblastoma cells after transfection with Control siRNA, LYAR siRNA-6 or LYAR siRNA-10
Project description:MYCN amplification in neuroblastoma leads to aberrant expression of MYCN oncoprotein, which binds active genes promoting transcriptional amplification. Yet how MYCN coordinates transcription elongation to meet productive transcriptional amplification and which elongation machinery represents MYCN-driven vulnerability remain to be identified. We conducted a targeted screen of transcription elongation factors and identified the super elongation complex (SEC) as a unique vulnerability in MYCN-amplified neuroblastomas. MYCN directly binds EAF1 and recruits SEC to enhance processive transcription elongation. Depletion of EAF1 or AFF1/AFF4, another core subunit of SEC, leads to a global reduction in transcription elongation and elicits selective apoptosis of MYCN-amplified neuroblastoma cells. A combination screen reveals SEC inhibition synergistically potentiates the therapeutic efficacies of FDA-approved BCL2 antagonist ABT-199, in part due to suppression of MCL1 expression, both in MYCN-amplified neuroblastoma cells and in patient-derived xenografts. These findings identify disruption of the MYCN-SEC regulatory axis as a promising therapeutic strategy in neuroblastoma.
Project description:Here we sought metabolic alterations specifically associated with amplified MYCN as nodes to indirectly target the MYCN oncogene. Liquid chromatography-mass spectrometry-based proteomics identified 7 proteins consistently correlated with MYCN in proteomes from 49 neuroblastoma biopsies and 13 cell lines. Among these were phosphoglycerate dehydrogenase (PHGDH), the rate-limiting enzyme in de novo serine synthesis. MYCN associated with two regions in the PHGDH promoter, supporting transcriptional PHGDH regulation by MYCN. Pulsed stable isotope-resolved metabolomics utilizing 13C-glucose labeling demonstrated higher de novo serine synthesis in MYCN-amplified cells compared to cells with diploid MYCN. An independence of MYCN-amplified cells from exogenous serine and glycine was demonstrated by serine and glycine starvation, which attenuated nucleotide pools and proliferation only in cells with diploid MYCN but did not diminish these endpoints in MYCN-amplified cells. Proliferation was attenuated in MYCN-amplified cells by CRISPR/Cas9-mediated PHGDH knockout or treatment with PHGDH small molecule inhibitors without affecting cell viability. PHGDH inhibitors administered as single-agent therapy to NMRI-Foxn1nu/nu mice harboring patient-derived MYCN-amplified neuroblastoma xenografts slowed tumor growth. However, combining a PHGDH inhibitor with the standard-of-care chemotherapy drug, cisplatin, revealed antagonism of chemotherapy efficacy in vivo. Emergence of chemotherapy resistance was confirmed in the genetic PHGDH knockout model in vitro. Altogether, PHDGH knockout and inhibition by small molecules consistently slows proliferation, but stops short of killing the cells, which then establish resistance to classical chemotherapy. Although PHGDH inhibition with small molecules has produced encouraging results in other preclinical cancer models, this approach must be considered with caution in patients with neuroblastoma.
Project description:<p>Neuroblastoma is the most common extra-cranial solid tumor in children. It represents 8% to 10% of all childhood cancers. Stage 4 Neuroblastoma is characterized by its clinical heterogeneous outcome. The special category, stage 4S tumors (2-5% of all NB) are chemo-sensitive, and the patients show spontaneous regression. On the other hand, MYCN amplification (25-30% of all NB) is associated with poor outcome of neuroblastoma, thus we further categorize stage 4 neuroblastoma into MYCN non-amplified and MYCN amplified group. Here we use transcriptome sequencing to characterize the transcriptome in 29 stage 4 Neuroblastoma samples.</p>
Project description:Neuroblastoma is the third most common pediatric cancer and is responsible for approximately 15% of all childhood cancer deaths (Maris & Matthay, 1999). In our analysis, we found that poor patient survival with increasing mRNA expression level of AURKA and AURKB in Mycn-amplified neuroblastoma. In the light of this evidence, we were able to find possibilities of existing inhibitors for therapy. According to the following experiments, we found that tozasertib, a pan-Aurora kinase inhibitor, has high therapeutic potential in neuroblastoma treatment. First, we performed in vitro experiments to reveal that tozasertib suppressed cell proliferation in multiple Mycn-amplified neuroblastoma cell lines. Next, we evaluated ex vivo not only in Mycn-amplified neuroblastoma xenograft mouse model but also TH-Mycn transgenic mouse model. The results showed that tozasertib significantly inhibited the tumor growth and prolonged the survival probability in both animal models. Finally, we explored the mechanism of tozasertib-treated tissues in two animal models by iTRAQ proteomic.
Project description:We used mass spectrometry-based proteomics to unravel anaplastic lymphoma kinase (ALK) signaling in the ALK and MYCN amplified neuroblastoma cell line, NB1. We specifically measured the ALK phosphoproteome upon siRNA depletion of ALK and upon ALK inhibition using the ALK-targeting small-molecule inhibitor lorlatinib. For quantitative phosphoproteomics we used a tandem mass tag (TMT)-based approach. Conditions for the TMT 11-plex setup is specified below. For each siRNA depletion experiment, NB1 cells were treated with siRNA (80 nM; as specified below) for 48 hours prior to stimulation with 0.1% DMSO for 30 minutes. For inhibitor treatment, NB1 cells were treated for 30 minutes with either 10 microM or 10 nM lorlatinib. The experimental treatment conditions and TMT11-plex labeling are specified below: 126: siControl replicate 1, 0.1% DMSO 127N: siControl replicate 2, 0.1% DMSO 127C: siControl replicate 3, 0.1% DMSO 128N: siALK sequence 1, 0.1% DMSO 128C: siALK sequence 2, 0.1% DMSO 129N: siALK mix of sequence 1 and 2, 0.1% DMSO 129C: 10 microM lorlatinib replicate 1 130N: 10 microM lorlatinib replicate 2 130C: 10 microM lorlatinib replicate 3 131N: 10 nM lorlatinib replicate 1 131C: 10 nM lorlatinib replicate 2
Project description:Neuroblastoma is an embryonal neoplasm that remains of dramatic prognosis in its aggressive forms. Activating mutations of the ALK tyrosine kinase receptor have been identified in sporadic and familial cases of this cancer. We generated knock-in mice carrying the two most frequent Alk mutations observed in neuroblastoma patients. We used microarrays to detail the global programme of gene expression underlying the impact of ALK mutations on neuroblastoma formation in a MYCN amplified background. We selected several murine neuroblastoma tumors for RNA extraction and hybridization on Affymetrix microarrays. We generated three groups of tumors: 10 MYCN amplified tumors, 11 MYCN amplified/ALK F1174L tumors and 10 MYCN amplified/ALK R1275Q tumors.
Project description:MYCN-amplified neuroblastoma cells exhibit upregulation of translation regulation factors and ribosome biogenesis proteins as a result of MYCN-driven transcriptional amplification. Here, we treated MYCN-amplified and non-amplified neuroblastoma cells with a novel translation inhibitor, amidino-rocaglate CMLD12824, to compare the defects in translational efficiency.
Project description:Genome wide differential gene expression analysis after DDX21 knockdown by treatment with DOX in MYCN-amplified human neuroblastoma BE(2)-C cells stably transfected with DOX-indicible control shRNA, DDX21 shRNA-1 or DDX21 shRNA-2 DDX21 increases neuroblastoma cell proliferation by activating CEP55 gene transcription and increases its expression. We identified that knocking N-Myc increases DDX21 gene expression, therefore, we performed affymetrix micoarray studies to investigate what are the downstream target genes of DDX21.