4,495 research outputs found

    Therapeutic and prognostic strategies in neuroblastoma : exploring nuclear hormone receptors, MYC targets, and DIAPH3

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    Neuroblastoma (NB) is a pediatric cancer derived from the cells of neural crest origin that form the sympathoadrenal system. Typically, the tumor cells migrate along the spinal cord and spread to the chest, neck, and/or abdomen. Different clinical behaviors are observed in this disease: some tumors spontaneously regress without treatment, while others are highly aggressive and resistant to current therapies. Approximately 40% of high-risk NB patients have MYCN amplification while 10% have MYC (i.e. encoding c-MYC) overexpression. These patients have undifferentiated tumors with a poor prognosis. Our group previously found that the expression and activation of nuclear hormone receptors (NHRs) estrogen receptor alpha (ERα) by 17-β-estradiol (E2), and the glucocorticoid receptor (GR) by dexamethasone (DEX), could trigger differentiation by disrupting the regulation of the miR-17 ~ 92 microRNA cluster by MYCN. In paper I, we sought to investigate whether the simultaneous activation of both ERα and GR has a more beneficial effect compared to the activation of either ERα or GR alone. We examined cell survival, alterations in cell shape as indicated by neurite extension, variations in metabolic pathways, accumulation of lipid droplets, and performed xenograft experiments. Our findings revealed that the simultaneous activation of GR and ERα, compared to their single activation, led to reduced viability and a more robust differentiation. This dual activation also caused changes in glycolysis and oxidative phosphorylation, increased lipid droplet accumulation, and decreased aggressiveness in mouse models. The triple activation with an additional activation of the retinoic acid receptor using all trans-retinoic acid (ATRA), amplified the differentiation phenotype. Bulk-sequencing analysis showed that patients with high levels of NHRs are related to favorable survival and clinical outcome. In summary, our data suggest that combination activation of these NHRs could be a potential differentiation induction treatment. Paper II investigates target genes of c-MYC and MYCN to explore if it is possible to obtain a better prognosis prediction using the expression of this group of genes, instead of the expression of MYC and/or MYCN alone. In addition, we analyzed if there are different prediction power capabilities between c-MYC and MYCN target genes, and their different role during sympathoadrenal development. We screened lists of target genes by using comprehensive approaches, including differential expression analysis between clinical risk groups, INSS stages, MYCN amplification status, progression status; Univariate Cox regression analysis to select the target genes related to prognosis prediction power, and protein interaction network analysis to select genes that share a meaningful biology function. Following the training and validation of (LASSO) regression prediction models in three different patient cohorts (SEQC, Kocak, and Versteeg), we found that a risk score computed on c-MYC/MYCN target genes with prognostic value, could effectively classify patients in groups with different survival probabilities. The high-risk group of patients exhibited unfavorable clinical outcomes and low survival rates. Further, single cell RNA sequencing analysis revealed that c-MYC and MYCN targets have different expression patterns during sympathoadrenal development. Notably, genes linked to adverse outcomes were predominantly expressed in sympathoblasts in comparison to chromaffin cells. In summary, our research provides new insights into the importance of c-MYC/MYCN target genes during sympathoadrenal development and their value in predicting patient outcome. In paper III we studied the function of one member of the formin protein family involved in cytoskeleton modulation: Diaphanous Related Formin 3 (DIAPH3). We found that high DIAPH3 expression in NB tumors are associated with MYCN amplification, higher stage, risk, progression and negative clinical outcome. Elevated DIAPH3 expression was also found in specific cells during mouse sympathoadrenal development and in progenitor cells of the post- natal human adrenal gland. Furthermore, the knockdown of DIAPH3 resulted in a slight decrease in cell growth and cell cycle arrest. Our study suggests that DIAPH3 could be a promising target for new therapeutic strategies

    Investigating the effects of palmitoylation on the dopamine 1 receptor (D1)

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    The dopamine D1 receptor (D1) is a G protein-coupled receptor (GPCR) which regulates various key brain functions like attention, movement, reward, and memory. Understanding D1 signalling may open the horizon for novel treatments for neurological disorders. Upon agonist activation, the heterotrimeric G proteins Gαs activate adenylyl cyclase to increase cAMP/PKA signalling. D1 also engages β-arrestin proteins leading to β-arrestin dependent signalling. The D1 has two palmitoylation sites on cysteines 347&351 in its C-tail domain. However, the distinct roles and implications of palmitoylation on the D1 signalling, trafficking and β-arrestins recruitment are still largely unexplored. A palmitoylation D1 mutant was generated and luminescent based techniques such as BRET and split-Nanoluc complementation assay were employed, to delineate D1 palmitoylation effects on its pharmacology and signalling. The D1 agonists induced 50% less cAMP production in the mutant compared to wildtype (WT) and WT showed a more efficient dissociation of its Gαs. Moreover, the mutant receptor failed to recruit β-arrestin1&2, induced less ERK1/2 activation and internalises in an agonist-independent process while showing an altered intracellular Golgi trafficking. Also, in β-arrestin 1&2 KO HEK 293 cells similar cAMP production levels were reported for D1 WT and palmitoylation mutant. β-arrestin 1&2 KO blocked agonist-induced WT D1 plasma membrane trafficking, indicating that these β-arrestins are driving the differences between WT and the palmitoylation mutant D1. Taken together, our studies indicate that Gαs is the main transducer for D1 cAMP and ERK1/2 signalling and that palmitoylation is essential for its β-arrestin 1&2 interactions and modulating D1 signalling cascades in a drug-dependant process

    Fanconi anaemia and LINE-1 retrotransposition in the mammalian genome

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    Transposable elements (TEs) are discrete, repetitive sequences of DNA that mobilise within genomes. For decades, TEs were dismissed as “junk DNA”, however, it is now clear that these elements have the potential to trigger genome instability, cause disease and shape the course of genome evolution. L1 elements constitute the only autonomous elements which remain active in the human genome and comprises approximately 17% of human DNA. As a retrotransposon, L1 canonically mobilises through a “cut and paste” mechanism called target primed reverse transcription (TPRT). Due to the deleterious impacts of L1 activity, mammalian cells have evolved a range of mechanisms to supress the mobilisation of these elements. The interactions between L1 elements and the host factors which regulate them are therefore an area of active research. Several DNA repair genes have shown potential as regulators of L1 activity. Moreover, in cell lines deficient in non-homologous end-joining, L1 has shown the potential to retrotranspose without its ORF2p endonuclease, which is usually a requirement for canonical TPRT. This retrotransposition has been termed endonuclease independent (ENi) retrotransposition, and takes place at unrepaired double stranded breaks in the DNA. Interestingly, several DNA repair factors have also been identified as potential regulators of L1 retrotransposition (both positive and negative), including a number of proteins from the Fanconi Anaemia pathway. The relationship between these factors and L1 has yet to be fully characterised, and it remains to be seen whether L1 can exploit other DNA lesions in the way that it utilises DSBs in ENi retrotransposition. This thesis aims to further investigate the relationship between L1 retrotransposition in the mammalian genome and DNA repair factors, particularly those comprising the Fanconi Anaemia pathway. Using cultured cell retrotransposition assays, I systematically tested a battery of mutant element in cells deficient in different proteins of the FANC pathway. In this way, I establish that ENi retrotransposition can be observed in a FANC background. I also demonstrate that FANC A deficient cells support retrotransposition of several L1 mutants which are immobile in parental cell lines. This includes elements with severe ORF1p mutations, mutations in the ORF2p endonuclease domain and mutations in the ORF2p PIP box. Despite testing a range of cell lines deficient in different DNA repair factors, including cells deficient in a range of FANC proteins, the retrotransposition of ORF1p, PIP and mutants appears to be unique to FANC A. My results are potentially indicative of a unique mechanism of retrotransposition in FANC A cells, a phenomena which has precedence in the ENi pathway of retrotransposition. Mass spectrometry of immunoprecipitated T7-tagged ORF1p, both in FANC A and parental cells, demonstrated that a different selection of host factors interact with ORF1p in the two cell lines. Several of these have not been previously identified as L1 interactors, including YTHDF2, a protein which binds and destabilises m6A-containing RNA. Previous reports suggest that YTHDF2 regulates the stability of RNA:DNA hybrids in vivo, and associates with R loop containing loci. Through co-immunoprecipitation of YTHDF2 with ORF1p, I confirm that the protein interacts with L1 elements in vitro

    Elucidating How MLH1 Loss Regulates a Metabolic Phenotype in Endometrial Cancer

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    Endometrial cancer is the fourth most common cancer in women and the most common gynaecological malignancy in the developed world. No new systemic treatments for endometrial cancer have been developed in recent years and its incidence is expected to double over the next decade. As such, there is a need to better understand key molecular pathways that are altered in the disease and could be targeted by novel treatments. The DNA MMR pathway is lost in approximately 30% of endometrial cancers. A small proportion of these are caused by germline mutations in one of the four MMR genes, however, the majority result from the epigenetic silencing of MLH1. Recently, our lab has shown that MLH1-deficient cells demonstrate a mitochondrial phenotype characterised by reduced OXPHOS, reduced mtDNA copy number and Complex I inhibition. OXPHOS-deficient cells must adapt their metabolism to compensate for energy defects and the inability to efficiently use the tricarboxylic acid cycle to generate energy. We hypothesise that this altered metabolism is driving tumourigenesis by increasing the tumour cells' metastatic potential. In this PhD we aimed to further investigate the influence MLH1 loss has on cellular metabolism using MLH1 positive and negative paired endometrial cell lines. Ultimately, we aim to understand whether altered metabolism in MLH1-deficient endometrial cancer may be therapeutically targeted

    CANCER TREATMENT BY TARGETING HDAC4 TRANSLOCATION INDUCED BY MICROSECOND PULSED ELECTRIC FIELD EXPOSURE: MECHANISTIC INSIGHTS THROUGH KINASES AND PHOSPHATASES

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    Epigenetic modifications, arising from sub-cellular shifts in histone deacetylase (HDAC) activity and localization, present promising strategies for diverse cancer treatments. HDACs, enzymes responsible for post-translational histone modifications, induce these epigenetic changes by removing acetyl groups from ε-N-acetyl-lysine residues on histones, thereby suppressing gene transcription. Within the HDAC group, class IIa HDACs are notable for their responsiveness to extracellular signals, bridging the gap between external stimuli, plasma membrane, and genome through nuclear-cytoplasmic translocation. This localization offers two significant mechanisms for cancer treatment: nuclear accumulation of HDACs represses oncogenic transcription factors, such as myocyte-specific enhancer factor 2C (MEF2C), triggering various cell death pathways. Conversely, cytoplasmic HDAC accumulation acts similarly to HDAC inhibitors by silencing genes. My dissertation introduces an innovative approach for glioblastoma and breast cancer treatment by investigating the application of microsecond pulsed electric fields. It particularly focuses on HDAC4, a class IIa HDAC overexpressed in these cancers. Beyond demonstrating HDAC4 translocation, my research delves into the intricate roles of kinases and phosphatases, shedding light on the underlying factors governing HDAC4 translocation

    Effects of municipal smoke-free ordinances on secondhand smoke exposure in the Republic of Korea

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    ObjectiveTo reduce premature deaths due to secondhand smoke (SHS) exposure among non-smokers, the Republic of Korea (ROK) adopted changes to the National Health Promotion Act, which allowed local governments to enact municipal ordinances to strengthen their authority to designate smoke-free areas and levy penalty fines. In this study, we examined national trends in SHS exposure after the introduction of these municipal ordinances at the city level in 2010.MethodsWe used interrupted time series analysis to assess whether the trends of SHS exposure in the workplace and at home, and the primary cigarette smoking rate changed following the policy adjustment in the national legislation in ROK. Population-standardized data for selected variables were retrieved from a nationally representative survey dataset and used to study the policy action’s effectiveness.ResultsFollowing the change in the legislation, SHS exposure in the workplace reversed course from an increasing (18% per year) trend prior to the introduction of these smoke-free ordinances to a decreasing (−10% per year) trend after adoption and enforcement of these laws (β2 = 0.18, p-value = 0.07; β3 = −0.10, p-value = 0.02). SHS exposure at home (β2 = 0.10, p-value = 0.09; β3 = −0.03, p-value = 0.14) and the primary cigarette smoking rate (β2 = 0.03, p-value = 0.10; β3 = 0.008, p-value = 0.15) showed no significant changes in the sampled period. Although analyses stratified by sex showed that the allowance of municipal ordinances resulted in reduced SHS exposure in the workplace for both males and females, they did not affect the primary cigarette smoking rate as much, especially among females.ConclusionStrengthening the role of local governments by giving them the authority to enact and enforce penalties on SHS exposure violation helped ROK to reduce SHS exposure in the workplace. However, smoking behaviors and related activities seemed to shift to less restrictive areas such as on the streets and in apartment hallways, negating some of the effects due to these ordinances. Future studies should investigate how smoke-free policies beyond public places can further reduce the SHS exposure in ROK

    Examining The Roles of Histone Methyltransferases in Heterochromatin Formation

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    The eukaryotic genome is meticulously stored inside the cell to control gene expression, protect the genome integrity, and facilitate cell division. The storage of genome is often achieved through epigenetic modifications. These modifications divide the genome into euchromatin and heterochromatin, each associated with gene expression and gene repression, respectively. Epigenetic modifications are often covalent modifications onto histone proteins or methylated DNA. On their own, some modifications can alter chromatin states, but most require specific epigenetic machinery that often termed epigenetic reader proteins. The epigenetic reader protein recognizes a specific epigenetic modification to alter chromatin states. For heterochromatin, these modifications often require heterochromatin protein 1 (HP1) to function. Heterochromatin represents a highly condensed form of chromatin that is often devoid of any transcriptional activities. Trimethylation of histone 3 lysine 9 (H3K9me3) and the presence of HP1 are the hallmarks and core players in heterochromatin formation. H3K9me3 recruits HP1, which when bound, can serve as a scaffold protein for more heterochromatin machinery. One key group of proteins HP1 recruits are the histone methyltransferases, the enzymes that catalyze the methylation of H3K9. The recruitment of HP1 often results in more H3K9me3 modifications, which can induce a positive feedback loop that results in a heterochromatin state. This group of histone methyltransferases all belong to the SET-domain family of proteins and demonstrate overlapping roles in heterochromatin formation. The redundancy within this group of enzymes calls for a better understanding in differentiating individual H3K9 methyltransferases. Does the redundancy suggest overlap in functionality or individual methyltransferases contribute to heterochromatin formation differently. The central hypothesis for this project is that different H3K9 methyltransferases can have different impacts on heterochromatin formation. By combining CiA-Oct4 cell line and Molecular biosystem, we have studied the intricacy of heterochromatin formation. Our SETDB1 knockdown cell lines show that SETDB1 contributes heavily to heterochromatin formation. SETDB1 knockdown cell lines have also shown reductions in H3K9me3 accumulation and impaired heterochromatin formation kinetics.Doctor of Philosoph

    Pan-cancer analysis of post-translational modifications reveals shared patterns of protein regulation

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    Post-translational modifications (PTMs) play key roles in regulating cell signaling and physiology in both normal and cancer cells. Advances in mass spectrometry enable high-throughput, accurate, and sensitive measurement of PTM levels to better understand their role, prevalence, and crosstalk. Here, we analyze the largest collection of proteogenomics data from 1,110 patients with PTM profiles across 11 cancer types (10 from the National Cancer Institute\u27s Clinical Proteomic Tumor Analysis Consortium [CPTAC]). Our study reveals pan-cancer patterns of changes in protein acetylation and phosphorylation involved in hallmark cancer processes. These patterns revealed subsets of tumors, from different cancer types, including those with dysregulated DNA repair driven by phosphorylation, altered metabolic regulation associated with immune response driven by acetylation, affected kinase specificity by crosstalk between acetylation and phosphorylation, and modified histone regulation. Overall, this resource highlights the rich biology governed by PTMs and exposes potential new therapeutic avenues

    Studying the interplay between ageing and Parkinson's disease using the zebrafish model

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    Parkinson’s disease (PD) is a neurodegenerative disorder characterised by the loss of dopaminergic neurons in the substantia nigra. Ageing is the major risk factor for developing PD but the interplay between ageing and PD remains elusive. To investigate the effect of ageing on PD-relevant pathological mechanisms, zebrafish mutant lines harbouring mutations in ageing-associated genes (klotho-/-, sirt1-/-, satb1a-/-, satb1b-/- and satb1a-/-;satb1b-/-) were generated, using CRISPR/Cas9 gene editing. Likewise, a chemical model for SIRT1 deficiency was utilised. klotho-/- zebrafish displayed an accelerated ageing phenotype at 3mpf and reduced survival to 6mpf. Dopaminergic neuron number, MPP+ susceptibility and microglial number were unaffected in klotho-/- larvae. NAD+ levels were decreased in 6mpf klotho-/- brains. However, ATP levels and DNA damage were unaffected. sirt1-/- zebrafish did not display a phenotype through adulthood. il-1β and il-6 were not upregulated in sirt1-/- larvae, and chemical inhibition of sirt1 did not increase microglial number. cdkn1a, il-1β and il-6 were not upregulated in satb1a-/- and satb1b-/- larvae. Dopaminergic neuron number and MPP+ susceptibility were unaffected in satb1a-/- larvae. However, satb1b-/- larvae demonstrated a moderate decrease in dopaminergic neuron number but equal susceptibility to MPP+ as satb1b+/+ larvae. Adult satb1a-/- but not adult satb1b-/- zebrafish were emaciated. satb1a-/-;satb1b-/- zebrafish did not display a phenotype through adulthood. Transgenic zebrafish expressing human wildtype α-Synuclein (Tg(eno2:hsa.SNCA-ires-EGFP)) were crossed with klotho-/- and sirt1-/- zebrafish, and treated with a sirt1-specific inhibitor. Neither genetic cross affected survival. The klotho mutation did not increase microglial number in Tg(eno2:hsa.SNCA-ires-EGFP) larvae. Likewise, sirt1 inhibition did not induce motor impairment or cell death in Tg(eno2:hsa.SNCA-ires-EGFP) larvae. In conclusion, the suitability of zebrafish for studying ageing remains elusive, as only 1 ageing-associated mutant line displayed accelerated ageing. However, zebrafish remain an effective model for studying PD-relevant pathological mechanisms due to the availability of CRISPR/Cas9 gene editing, neuropathological and neurobehavioral tools
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