RNA-sequencing in KELLY cells with oligonucleotide:leash lipoplexes
Ontology highlight
ABSTRACT: RNA-sequencing has been used to obtain transcriptome-wide differences that occur in paraspeckle-deficient, MYCN-amplified/model high-risk neuroblastoma cell lines with an increase in the long non-coding paraspeckle-associated NEAT1_2 RNA, to decipher the role of paraspeckles in this cancer type.
Project description:RNA-sequencing has been used to obtain and observe transcriptome-wide differences that occur in two parasspeckle-deficient, MYCN-amplified/model high-risk and one paraspeckle-abundant, non-MYCN-amplified/low-risk cell lines, to decipher the role of paraspeckles in this cancer type.
Project description:The nucleus is a highly structured environment containing multiple membrane-less bodies formed through liquid-liquid phase separation. These provide spatial separation and concentration of specific biomolecules enabling efficient and discrete processes to occur which regulate gene expression. One such nuclear body, paraspeckles, are comprised of multiple paraspeckle proteins (PSPs) built around the architectural RNA, NEAT1_2. Paraspeckle function is yet to be fully elucidated but has been implicated in a variety of developmental and disease scenarios. We demonstrate that Kaposi’s sarcoma-associated herpesvirus (KSHV) drives formation of structurally distinct paraspeckles with a dramatically increased size and altered protein composition that are essential for productive lytic replication. We highlight these virus-induced paraspeckle-like structures form adjacent to virus replication centres, functioning as RNA processing hubs for both viral and cellular transcripts during infection. Notably, we reveal that PSP sequestration into virus-induced paraspeckle-like structures results in increased genome instability during both KSHV and Epstein Barr virus (EBV) infection, implicating their formation in virus-mediated tumorigenesis.
Project description:The nucleus is a highly organised yet dynamic environment containing distinct membrane nuclear bodies. This spatial separation enables a subset of components to be concentrated within bimolecular condensates, allowing efficient and discrete processes to occur which regulate cellular function. One such nuclear body, paraspeckles, are comprised of multiple paraspeckle proteins (PSPs) built around the architectural RNA, NEAT1_2. Paraspeckle function is yet to be fully elucidated but has been implicated in a variety of developmental and disease scenarios. We demonstrate that Kaposi’s sarcoma-associated herpesvirus (KSHV) drives formation of structurally distinct paraspeckles with a dramatically increased size and altered protein composition that are essential for productive lytic replication. We highlight these virus-modified paraspeckles form adjacent to virus replication centres, functioning as RNA processing hubs for both viral and cellular transcripts during infection. Notably, we reveal that PSP sequestration into virus-modified paraspeckles results in increased genome instability during both KSHV and Epstein Barr virus (EBV) infection, implicating their formation in virus-mediated tumorigenesis.
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:The long non-coding RNA NEAT1 (nuclear enriched abundant transcript 1) nucleates the formation of paraspeckles, which constitute a type of nuclear body that has multiple roles in gene expression. How the NEAT1 gene itself is regulated and how paraspeckles communicate with other cell compartments remains poorly understood. Here we identify regulators of NEAT1 transcription using an endogenous NEAT1 promoter-driven EGFP reporter in human cells coupled with genome-wide RNAi screens. In addition to transcription factors and chromatin modulators, the screens unexpectedly yielded gene candidates involved in mitochondrial functions as essential regulators of NEAT1 expression and paraspeckle formation. Mitochondrial defects altered NEAT1 transcription via ATF2 and subsequently uncoupled 3’ end processing of NEAT1_1 from its long isoform to favour NEAT1_2 production, which is key for generating elongated paraspeckles that have different features from the regular, globular bodies. Correspondingly, NEAT1 depletion has profound effects on mitochondrial dynamics and function by altering sequestration of mRNAs of mitochondrial genes enriched in paraspeckles. Overall, our data provided a rich resource for understanding NEAT1 and paraspeckle regulation, and revealed an unexpected crosstalk between cytoplasmic organelles and nuclear bodies.
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: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: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:<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>