BackgroundTriple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited therapeutic opportunities. Recently, splicing factors have gained attention as potential... Show moreBackgroundTriple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited therapeutic opportunities. Recently, splicing factors have gained attention as potential targets for cancer treatment. Here we systematically evaluated the role of RNA splicing factors in TNBC cell proliferation.MethodsIn this study, we performed an RNAi screen targeting 244 individual splicing factors to systematically evaluate their role in TNBC cell proliferation. For top candidates, mechanistic insight was gained using amongst others western blot, PCR, FACS, molecular imaging and cloning. Pulldown followed by mass spectrometry were used to determine protein-protein interactions and patient-derived RNA sequencing data was used relate splicing factor expression levels to proliferation markers.ResultsWe identified nine splicing factors, including SNRPD2, SNRPD3 and NHP2L1, of which depletion inhibited proliferation in two TNBC cell lines by deregulation of sister chromatid cohesion (SCC) via increased sororin intron 1 retention and down-regulation of SMC1, MAU2 and ESPL1. Protein-protein interaction analysis of SNRPD2, SNRPD3 and NHP2L1 identified that seven out of the nine identified splicing factors belong to the same spliceosome complex including novel component SUN2 that was also critical for efficient sororin splicing. Finally, sororin transcript levels are highly correlated to various proliferation markers in BC patients.ConclusionWe systematically determined splicing factors that control proliferation of breast cancer cells through a mechanism that involves effective sororin splicing and thereby appropriate sister chromatid cohesion. Moreover, we identified SUN2 as an important new spliceosome complex interacting protein that is critical in this process. We anticipate that deregulating sororin levels through targeting of the relevant splicing factors might be a potential strategy to treat TNBC. Show less
Koedoot, E.; Steijn, E. van; Vermeer, M.; Gonzalez Prieto, R.; Vertegaal, A.C.O.; Martens, J.W.M.; ... ; Water, B. van de 2021
BackgroundTriple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited therapeutic opportunities. Recently, splicing factors have gained attention as potential... Show moreBackgroundTriple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited therapeutic opportunities. Recently, splicing factors have gained attention as potential targets for cancer treatment. Here we systematically evaluated the role of RNA splicing factors in TNBC cell proliferation.MethodsIn this study, we performed an RNAi screen targeting 244 individual splicing factors to systematically evaluate their role in TNBC cell proliferation. For top candidates, mechanistic insight was gained using amongst others western blot, PCR, FACS, molecular imaging and cloning. Pulldown followed by mass spectrometry were used to determine protein-protein interactions and patient-derived RNA sequencing data was used relate splicing factor expression levels to proliferation markers.ResultsWe identified nine splicing factors, including SNRPD2, SNRPD3 and NHP2L1, of which depletion inhibited proliferation in two TNBC cell lines by deregulation of sister chromatid cohesion (SCC) via increased sororin intron 1 retention and down-regulation of SMC1, MAU2 and ESPL1. Protein-protein interaction analysis of SNRPD2, SNRPD3 and NHP2L1 identified that seven out of the nine identified splicing factors belong to the same spliceosome complex including novel component SUN2 that was also critical for efficient sororin splicing. Finally, sororin transcript levels are highly correlated to various proliferation markers in BC patients.ConclusionWe systematically determined splicing factors that control proliferation of breast cancer cells through a mechanism that involves effective sororin splicing and thereby appropriate sister chromatid cohesion. Moreover, we identified SUN2 as an important new spliceosome complex interacting protein that is critical in this process. We anticipate that deregulating sororin levels through targeting of the relevant splicing factors might be a potential strategy to treat TNBC. Show less
BackgroundFrequent activation of the co-transcriptional factor YAP is observed in a large number of solid tumors. Activated YAP associates with enhancer loci via TEAD4-DNA-binding protein and... Show moreBackgroundFrequent activation of the co-transcriptional factor YAP is observed in a large number of solid tumors. Activated YAP associates with enhancer loci via TEAD4-DNA-binding protein and stimulates cancer aggressiveness. Although thousands of YAP/TEAD4 binding-sites are annotated, their functional importance is unknown. Here, we aim at further identification of enhancer elements that are required for YAP functions.ResultsWe first apply genome-wide ChIP profiling of YAP to systematically identify enhancers that are bound by YAP/TEAD4. Next, we implement a genetic approach to uncover functions of YAP/TEAD4-associated enhancers, demonstrate its robustness, and use it to reveal a network of enhancers required for YAP-mediated proliferation. We focus on Enhancer(TRAM2), as its target gene TRAM2 shows the strongest expression-correlation with YAP activity in nearly all tumor types. Interestingly, TRAM2 phenocopies the YAP-induced cell proliferation, migration, and invasion phenotypes and correlates with poor patient survival. Mechanistically, we identify FSTL-1 as a major direct client of TRAM2 that is involved in these phenotypes. Thus, TRAM2 is a key novel mediator of YAP-induced oncogenic proliferation and cellular invasiveness.ConclusionsYAP is a transcription co-factor that binds to thousands of enhancer loci and stimulates tumor aggressiveness. Using unbiased functional approaches, we dissect YAP enhancer network and characterize TRAM2 as a novel mediator of cellular proliferation, migration, and invasion. Our findings elucidate how YAP induces cancer aggressiveness and may assist diagnosis of cancer metastasis. Show less
Chondrosarcoma is the second most common primary bone malignancy, representing one fourth of all primary bone sarcomas. It is typically resistant to radiation and chemotherapy treatments. However,... Show moreChondrosarcoma is the second most common primary bone malignancy, representing one fourth of all primary bone sarcomas. It is typically resistant to radiation and chemotherapy treatments. However, the molecular mechanisms that contribute to cancer aggressiveness in chondrosarcomas remain poorly characterized. Here, we studied the role of mitochondrial transporters in chondrosarcoma aggressiveness including chemotherapy resistance. Histological grade along with stage are the most important prognostic biomarkers in chondrosarcoma. We found that high-grade human chondrosarcoma tumors have higher expression of the mitochondrial protein, translocase of the outer mitochondrial membrane complex subunit 20 (TOMM20), compared to low-grade tumors. TOMM20 overexpression in human chondrosarcoma cells induces chondrosarcoma tumor growth in vivo. TOMM20 drives proliferation, resistance to apoptosis and chemotherapy resistance. Also, TOMM20 induces markers of epithelial to mesenchymal transition (EMT) and metabolic reprogramming in these mesenchymal tumors. In conclusion, TOMM20 drives chondrosarcoma aggressiveness and resistance to chemotherapy. Show less
Balbi, C.; Lodder, K.; Costa, A.; Moimas, S.; Moccia, F.; Herwaarden, T. van; ... ; Bollini, S. 2019
The data and information presented here refer to the research article entitled: "Reactivating endogenous mechanisms of cardiac regeneration via paracrine boosting with the human amniotic fluid stem... Show moreThe data and information presented here refer to the research article entitled: "Reactivating endogenous mechanisms of cardiac regeneration via paracrine boosting with the human amniotic fluid stem cell secretome" (Balbi et al., 2019, Apr 04). This dataset illustrates the in vitro paracrine effect exerted by the human amniotic fluid stem cell secretome on rodent neonatal cardiomyocytes, human endothelial progenitors and different subsets of cardiac progenitor cells. Cytokine/chemokine profiling of the human amniotic fluid stem cell secretome is provided as well. This data can provide useful insights in regenerative medicine as demonstrating the in vitro cardioprotective and proliferative secretory paracrine potential of human fetal stem cells. (c) 2019 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Show less
Cell transplantation studies have shown that injection of progenitor cells can improve cardiac function after myocardial infarction (MI). Transplantation of human cardiac progenitor cells (hCPCs)... Show moreCell transplantation studies have shown that injection of progenitor cells can improve cardiac function after myocardial infarction (MI). Transplantation of human cardiac progenitor cells (hCPCs) results in an increased ejection fraction, but survival and integration are low. Therefore, paracrine factors including extracellular vesicles (EVs) are likely to contribute to the beneficial effects. We investigated the contribution of EVs by transplanting hCPCs with reduced EV secretion. Interestingly, these hCPCs were unable to reduce infarct size post-MI. Moreover, injection of hCPC-EVs did significantly reduce infarct size. Analysis of EV uptake showed cardiomyocytes and endothelial cells primarily positive and a higher Ki67 expression in these cell types. Yes-associated protein (YAP), a proliferation marker associated with Ki67, was also increased in the entire infarcted area. In summary, our data suggest that EV secretion is the driving force behind the short-term beneficial effect of hCPC transplantation on cardiac recovery after MI. Show less
Until a few years ago, only two human polyomaviruses (JC and BK) were known to infect humans and cause severe illness in immunocompromised hosts. Since 2007, at least eleven new polyomaviruses... Show moreUntil a few years ago, only two human polyomaviruses (JC and BK) were known to infect humans and cause severe illness in immunocompromised hosts. Since 2007, at least eleven new polyomaviruses became known that infect humans. Among them is the polyomavirus associated with trichodysplasia spinulosa (TSPyV). In Chapter 1 of this dissertation, the main focus is on the recent developments in studying the newly identified human polyomaviruses until mid-2014. This introductory chapter sets the stage for further investigation into TSPyV infection, pathogenesis, evolution and host adaptation, which is detailed in Chapter 2. To study causality between TSPyV infection and TS disease, in Chapter 3, the prevalence, load and localization of this virus is described. In Chapter 4, the cellular mechanisms behind disruption of cellular proliferation and TS spicule formation by TSPyV Large T-antigen is investigated. By In-silico analysis, in Chapter 5, the identification of a polyomavirus evolution and adaptation mechanism called COCO-VA is highlighted. Subsequently, in Chapter 6, TSPyV genome sequences are tested to gain more insight into this COCO-VA mechanism. Finally, in Chapter 7, the findings described in this dissertation are discussed with regard to several TSPyV aspects, and compared to existing knowledge about polyomaviruses in a broader context. Show less
Helminth parasites are able to induce immune regulation in their host. Suppression of the host immune system is beneficial for both the parasite, by inhibiting anti-parasite immunity, and for the... Show moreHelminth parasites are able to induce immune regulation in their host. Suppression of the host immune system is beneficial for both the parasite, by inhibiting anti-parasite immunity, and for the host, by preventing tissue damage due to excessive inflammation. There are indications that in countries where parasites have been eliminated the immune regulatory network is impaired, leading to inflammatory diseases such as allergies and asthma. An important player in immune regulation is the regulatory T cell (Treg). We have shown that the number and/or function of Tregs were indeed enhanced in several helminth and also malaria infections in humans. Tregs were not only involved in suppression of anti-parasite responses, but also of responses to other infections or vaccines. We further investigated the effect of helminth elimination in a randomized placebo-controlled trial. Treatment of helminths led to a strong increase in __mainly pro-inflammatory__ immune responses, which confirms the importance of immune regulation during infection. Furthermore, the prevalence of malaria was transiently increased and allergy was slightly on the rise in treated school children. These results further endorse the possible beneficial effects of helminthic therapy, which is currently being tested in a number of clinical trials. Show less
Dexamethasone (DEX), a synthetic glucocorticoid, has been used to treat respiratory distress syndrome in prematurely born infants. Despite the important short-term benefit on lung function, there... Show moreDexamethasone (DEX), a synthetic glucocorticoid, has been used to treat respiratory distress syndrome in prematurely born infants. Despite the important short-term benefit on lung function, there is growing concern about the long-term outcome of this treatment, since follow-up studies of prematurely born infants have shown lasting adverse neurodevelopmental effects. Since the mechanism underlying these neurodevelopmental impairments is largely unknown, the aim of the present study was (i) to investigate the acute effects of neonatal DEX treatment on the developing brain; and (ii) to block specifically the effects of DEX on the brain by central administration of the glucocorticoid receptor (GR) antagonist mifepristone. Long Evans rat pups were injected subcutaneously with tapering doses of DEX or saline (SAL) on postnatal days (pnd) 1, 2 and 3. Separate groups received intracerebroventricular injections with mifepristone prior to DEX treatment. On pnd 4 and 10, pups were sacrificed and brains collected for analysis of cell proliferation (Ki-67) and astrogliosis (GFAP). We report that neonatal DEX treatment reduced hippocampal cell proliferation on pnd 4, an effect that was normalized by pnd 10. Although on pnd 4, GFAP expression was not affected, DEX treatment caused a significant reduction in the number and density of astrocytes in hippocampus and corpus callosum on pnd 10, which was normalized by mifepristone pre-treatment. These acute alterations in the neonate brain might underlie later functional impairments reported in DEX-treated animals and humans and further illustrate the impact of early GR activation on brain development. (C) 2012 Elsevier B.V. All rights reserved. Show less
Synthetic glucocorticoids such as dexamethasone are frequently used to enhance pulmonary development in preterm ventilator-dependent infants. In contrast to the short-term benefit on survival and... Show moreSynthetic glucocorticoids such as dexamethasone are frequently used to enhance pulmonary development in preterm ventilator-dependent infants. In contrast to the short-term benefit on survival and lung maturation, early glucocorticoid exposure has been shown to adversely affect neurodevelopmental processes. Both human and animal studies have reported acute and long-lasting impairments, including shortening of the lifespan in rodents. Therefore, the objective of the studies described in this thesis was to investigate, using an animal model: 1) the short- and long-term consequences of neonatal dexamethasone treatment and 2) the possibility to prevent these effects using pharmacological and behavioural intervention strategies. We reported that systemic dexamethasone treatment acutely affects brain development by suppressing cell proliferation and glial activity. These acute effects on the brain can be partially prevented by central glucocorticoid receptor antagonist pre-treatment, which might serve as a protective strategy against the adverse effects of dexamethasone treatment on the developing brain. Although neonatal dexamethasone exposure clearly affects the developmental trajectory, we did not observe the frequently described detrimental long-lasting consequences of this treatment. We showed that daily handling of the neonate, which was an inevitable component of our experimental design and leads to enhanced levels of maternal care towards the offspring, may compensate for some of the adverse effects of dexamethasone treatment. We conclude that the impact of neonatal glucocorticoid exposure highly depends on interactions with other components of the early environment and is therefore susceptible to pharmacological and behavioural intervention strategies. Show less
Lashley, L.E.E.L.O.; Hoorn, M.L.P. van der; Mast, B.J. van der; Tilburgs, T.; Lee, N. van der; Keur, C. van der; ... ; Scherjon, S.A. 2011
Head and Neck Paragangliomas (HNP) are hypervascular tumours characterised by a slow growth pattern and a strong hereditary context that originate from the neural crest derived paraganglia, which... Show moreHead and Neck Paragangliomas (HNP) are hypervascular tumours characterised by a slow growth pattern and a strong hereditary context that originate from the neural crest derived paraganglia, which are associated with the autonomous nervous system and are situated at several locations in the head and neck region. Inactivating mutations in subunits of complex II (SDH) of the mitochondrial respiratory chain are responsible for hereditary tumours and have lead to a novel concept of mitochondrial tumoursupressor-genes and further insight in the intricate association of cellular oxygen sensing mechanisms and (pseudo)-hypoxia as environmental risk factors. However, further characterisation of the tumour biology is warranted for better understanding of the natural behaviour of HNP and possible identification clinicopathological parameters that could aid the clinician in his treatment decisions. In this thesis several studies on the molcular pathology of HNP are discussed including genotype-fenotype relations, the role of bFGF in tumourgenisis, the interplay between proliferation, cell cycle activity and apoptosis, and the nature of sustentacular cells in these apparent biphasic tumours. Additionally, in a clincal study the prevalence of synchronic or metachronic pheochromocytomas in patients with SDHD-linked HNP was determined. Show less
Cholesteatoma is a benign, gradually expanding destructive epithelial lesion of the temporal bone, often accompanied with inflammation. The complications can be severe, e.g., destruction of the... Show moreCholesteatoma is a benign, gradually expanding destructive epithelial lesion of the temporal bone, often accompanied with inflammation. The complications can be severe, e.g., destruction of the ossicular chain and otic capsule with consecutive hearing loss. Several hypotheses for the pathogenesis of human cholesteatoma have been proposed but are still controversial. In this thesis, protein signaling pathways were investigated which are involved in different aspects of cholesteatoma pathogenesis, such as hyperproliferation, aberrant differentiation, and extra-cellular matrix deposition. In cholesteatoma epithelium increased expressions of those proteins were found which are involved in proliferation (Ki-67), cell cycle arrest (p53, p21), early terminal differentiation (involucrin) and survival (pAKT). The proteins of which the expressions were decreased were those concerning late terminal differentiation (filaggrin) and apoptosis (active caspase 3). Moreover, increased activation of MAPK- and its association with TGF_ cellular signaling cascades were demonstrated. In cholesteatoma stroma, increased extracellular matrix deposition, visualized by accumulation of EDA-Fibronectin, was present. These results were placed in the context of the interconnected signaling processes of wound healing. Concluding: cholesteatoma behaves as a chronic wound in which a persistent inflammation appears to be a contributing factor to its chronicity. Research into pharmacological interventions aimed at control of inflammation is recommended. Show less
The work described in this thesis was aimed at identifying the role of cell cycle and apoptosis genes in atherosclerosis. Atherosclerosis is the primary cause of cardiovascular disease, a disorder... Show moreThe work described in this thesis was aimed at identifying the role of cell cycle and apoptosis genes in atherosclerosis. Atherosclerosis is the primary cause of cardiovascular disease, a disorder occurring in the large and medium-sized arteries of the body. Although in the beginning 90s promising lipid lowering therapies predicted a strong reduction in cardiovascular deaths, in westernized societies it is still the underlying cause of about 40% of all deaths, indicating that treatment of atherosclerosis goes beyond lipid lowering solely. In addition to lipids, continuous cell growth (cell cycle) and cell death (i.e. apoptosis and necrosis) processes play a central role in the development of atherosclerosis. To investigate the role of several cell cycle and apoptosis genes (i.e. p53, Rb and Mdm2) in atherosclerosis we generated and characterized several mouse models based on site-specific recombinase (SSR) technology. The studies described in this thesis show that next to therapies aiming at lifestyle interventions, lipid therapies and regulation of inflammation, targeting cell cycle and apoptosis genes on lesional or cellular level might prove the most effective way to reduce the burden of atherosclerosis. Show less
