Current preclinical models in tumor biology are limited in their ability to recapitulate relevant (patho-) physiological processes, including autophagy. Three-dimensional (3D) growth cultures have frequently been proposed to overcome the lack of correlation between two-dimensional (2D) monolayer cell cultures and human tumors in preclinical drug testing. Besides 3D growth, it is also advantageous to simulate shear stress, compound flux and removal of metabolites, e.g. via bioreactor systems, through which culture medium is constantly pumped at a flow rate reflecting physiological conditions. Here, we show that both Staticic 3D growth and 3D growth within a bioreactor system modulate key hallmarks of cancer cells, including proliferation and cell death as well as macroautophagy, a recycling pathway often activated by highly proliferative tumors to cope with metabolic stress. The autophagy-related gene expression profiles of 2D- and 3D-grown cells are substantially different, with the 3D-grown cells exhibiting an expression profile closely resembling the (patho-) physiological Statice of a tumor. Underscoring the importance of this pathway, autophagy-controlling transcription factors, such as TFEB and FOXO3, are upregulated in tumors, and 3D-grown cells have increased expression compared with cells grown in 2D conditions. Three-dimensional cultures depleted of the autophagy mediators BECN1, ATG5 or ATG7 or the transcription factor FOXO3, are more sensitive to cytotoxic treatment. Accordingly, combining cytotoxic treatment with compounds affecting late autophagic flux, such as chloroquine, renders the 3D-grown cells more susceptible to therapy and increases intracellular doxorubicin concentration to the level of 2D-grown cells. Altogether, 3D cultures are a valuable tool to study drug response of tumor cells, as these models recapitulate (patho-) physiologically relevant pathways, such as autophagy.
Three-dimensional tumor cell growth stimulates autophagic flux and recapitulates chemotherapy resistance.
Specimen part, Cell line
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Reduced chromatin binding of MYC is a key effect of HDAC inhibition in MYC amplified medulloblastoma.
Specimen part, Treatment
View SamplesMYC is a driver oncogene in many cancers. Inhibition of MYC promises high therapeutic potential, but specific MYC inhibitors remain unavailable for clinical use. Previous studies suggest that MYC amplified Medulloblastoma cells are vulnerable to HDAC inhibition. Using co-immunoprecipitation, mass spectrometry and ChIP-sequencing we show that HDAC2 is a cofactor of MYC in MYC amplified primary medulloblastoma and cell lines. The MYC-HDAC2 complex is bound to genes defining the MYC-dependent transcriptional profile. Class I HDAC inhibition leads to stabilization and reduced DNA binding of MYC protein inducing a down-regulation of MYC activated genes (MAGs) and up-regulation of MYC repressed genes (MRGs). MAGs and MRGs are characterized by opposing biological functions and distinct E-box distribution. We conclude that MYC and HDAC2 (class I) are localized in a complex in MYC amplified medulloblastoma and drive a MYC-specific transcriptional program, which is reversed by the class I HDAC inhibitor entinostat. Thus, the development of HDAC inhibitors for treatment of MYC amplified medulloblastoma should include HDAC2 in its profile in order to directly target MYC´s trans-activating and trans-repressing function.
Reduced chromatin binding of MYC is a key effect of HDAC inhibition in MYC amplified medulloblastoma.
Specimen part, Treatment
View SamplesGray leaf spot (GLS) disease of maize can be caused by either of two sibling fungal species Cercospora zeina or Cercospora zeae-maydis. These species differ in geographical distribution, for example to date only C. zeina is associated with GLS in African countries, such as South Africa. Maize inbred line B73, which is susceptible to GLS, was planted in the field, and subjected to natural infection with C. zeina. Samples were collected from lower leaves with substantial GLS lesions and younger upper leaves of the same plants with very few immature GLS lesions. The first aim of the experiment was to determine which maize genes are induced in response to C. zeina infection. The second aim was to identify C. zeina genes expressed in planta during a compatible interaction. The third aim was to determine whether the C. zeina cercosporin biosynthetic (CTB) genes are expressed in planta. C. zeina fails to produce cercosporin in vitro in contrast to C. zeae-maydis. Cercosporin is a phytotoxin that is thought to play a role in pathogenicity of several Cercospora spp., however its role in the pathogenicity strategy of C. zeina is currently under investigation. Overall design: To collect material that reflected a difference between C. zeina infected B73 leaves and control B73 leaf material, samples were collected from two lower GLS infected leaves (second and third leaf internode below ear), and two upper leaves with minimal GLS symptoms (second and third internode above ear), respectively. The two lower leaves from each plant were pooled prior to RNA extraction, and the two upper leaves from each plant were pooled prior to RNA extraction. Upper and lower leaf samples from three maize B73 plants were subjected to RNA sequencing individually. The three maize plants were selected randomly as one plant per row from three rows of ten B73 plants each.
Complementation of CTB7 in the Maize Pathogen Cercospora zeina Overcomes the Lack of In Vitro Cercosporin Production.
Specimen part, Subject
View SamplesRelative expression data from germinating seeds of Columbia (wt), the pkl mutant (pkl), Columbia plus uniconazole-P (Uwt) and the pkl-mutant plus uniconazole-P (Upkl).
The CHD3 remodeler PICKLE promotes trimethylation of histone H3 lysine 27.
No sample metadata fields
View SamplesGinkgo biloba leaf extract (GBE) has been used for centuries in traditional Chinese medicine and today is used as an herbal supplement for various indications such as improving neural function, anti-oxidant and anti-cancer effects. As part of the herbal supplement industry, these compounds are largely unregulated, and may be consumed in large concentrations over extended periods of time. This is of particular concern, because the long-term effects in terms of toxicity and carcinogenicity data is lacking for many herbal products, including GBE. The 2-year B6C3F1 mouse carcinogenicity bioassay indicated a marked dose-related increase in hepatocellular carcinoma (HCC) development associated with exposure to GBE. We have shown that the mechanism of this increase in tumorigenesis is related to a marked increase in the incidence of -catenin mutation, and report a novel mechanism of constitutive -catenin activation through post-translational modification leading to constitutive Wnt signaling and unregulated growth signaling and oncogenesis. Furthermore, using global gene expression profiling, we show that GBE-induced HCC exhibit overrepresentation of gene categories associated with human cancer and HCC signaling including upregulation of relevant oncogenes and suppression of critical tumor suppressor genes, as well as chronic oxidative stress, a known inducer of calpain-mediated degradation and promoter of hepatocarcinogenesis in humans. These data provide a molecular mechanism to GBE-induced HCC in B6C3F1 mice that is relevant to human cancer, and provides relevant molecular data that will provide the groundwork for further risk assessment of unregulated compounds, including herbal supplements.
Hepatocellular carcinomas in B6C3F1 mice treated with Ginkgo biloba extract for two years differ from spontaneous liver tumors in cancer gene mutations and genomic pathways.
Specimen part
View SamplesThe bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-4 (PFKFB4) controls metabolic flux through allosteric regulation of glycolysis. Here we show that p53 regulates the expression of PFKFB4 and that p53-deficient cancer cells are highly dependent on the function of this enzyme. We found that p53 down-regulates PFKFB4 expression by binding to its promoter and mediating transcriptional repression via histone deacetylases. Depletion of PFKFB4 from p53 deficient cancer cells increased levels of the allosteric regulator fructose 2,6-bisphophate, leading to increased glycolytic activity but decreased routing of metabolites through the oxidative arm of the pentose phosphate pathway. PFKFB4 was also required to support the synthesis and regeneration of nicotinamide adenine dinucleotide phosphate (NADPH) in p53 deficient cancer cells. Moreover, depletion of PFKFB4 attenuated cellular biosynthetic activity and resulted in the accumulation of reactive oxygen species and cell death in the absence of p53. Finally, silencing of PFKFB4 induced apoptosis in p53 deficient cancer cells in vivo and interfered with tumour growth. These results demonstrate that PFKFB4 is essential to support anabolic metabolism in p53-deficient cancer cells and suggest that inhibition of PFKFB4 could be an effective strategy for cancer treatment. Overall design: Gene expression changes in HCT116 p53+/+ and p53-/- xenograft tumours after PFKFB4 silencing
6-Phosphofructo-2-kinase/fructose-2,6-biphosphatase 4 is essential for p53-null cancer cells.
Specimen part, Cell line, Subject
View SamplesThese arrays contain data from the livers of 10 week old L-Pex5 -/- male mice
Carbohydrate metabolism is perturbed in peroxisome-deficient hepatocytes due to mitochondrial dysfunction, AMP-activated protein kinase (AMPK) activation, and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) suppression.
Sex, Age, Specimen part
View SamplesWe profile gene expression changes in two mutant strains lacking the D. melanogaster HP1 homolog HP1B at the third instar larval stage. Compared to the yw control strain, several hundred genes are deregulated, with metabolic genes being over-represented among the deregulated gene set. Overall design: Examination of gene expression in two genotypes
HP1B is a euchromatic Drosophila HP1 homolog with links to metabolism.
Specimen part, Cell line, Subject
View SamplesRefined cancer models are required to assess the burgeoning number of potential targets for cancer therapeutics within a rapid and clinically relevant context. Here we utilize tumor-associated genetic pathways to transform primary human epithelial cells from epidermis, oropharynx, esophagus, and cervix into genetically defined tumors within an entirely human 3-dimensional (3-D) tissue environment incorporating cell-populated stroma and intact basement membrane (BM). These engineered organotypic tissues recapitulated natural features of tumor progression, including epithelial invasion through the BM, a complex process critically required for biologic malignancy in 90% of human cancers. Invasion was rapid, and potentiated by stromal cells. Oncogenic signals in 3-D tissue, but not 2-D culture, resembled gene expression profiles from spontaneous human cancers. Screening well-characterized signaling pathway inhibitors in 3-D organotypic neoplasia helped distil a clinically faithful cancer gene signature. Multi-tissue 3-D human tissue cancer models may provide an efficient and relevant complement to current approaches to characterize cancer progression.
Invasive three-dimensional organotypic neoplasia from multiple normal human epithelia.
No sample metadata fields
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