Tris(2-chloroethyl) phosphate (TCEP) is a pervasive flame retardant that has been identified as a chemical of concern given its health effects and therefore its use has since been tightly regulated. Tris(2-chloroisopropyl) phosphate (TCIPP), an analogue of TCEP, is believed to be its replacement. However, compared to TCEP, little is known of the toxicological impacts of TCIPP. We used RNA sequencing as unbiased and sensitive tool to identify and compare effects on a transcriptome level of TCEP and TCIPP in the human hepatocellular carcinoma cell line, HepG2. We identified that compared to other flame retardants, TCEP and TCIPP had little cytotoxicity. Treatment with sub-cytotoxic concentrations of the two compounds revealed that both chemicals elicited similar effects; both compounds were found to affect genes involved in immune responses and steroid hormone biosynthesis, while also affecting xenobiotic metabolism pathways in a similar manner. Specifically for effects on immune responses, both compounds were shown to alter the expression of the receptor of the potent and pleiotropic complement component, C5a. Additionally, expression of genes encoding for effector proteins involved in the complement cascade along with other potent inflammatory regulators were found altered in response to TCEP and TCIPP, further emphasizing their potential effects on immune function. Taken together, given that TCIPP elicited similar effects compared to TCEP, and at lower concentrations, the potential health effects of TCIPP need to be further studied for a complete risk assessment of the compound. Overall design: HepG2 cells were treated with low (25 uM) or high (250 uM) concentrations of tris(2-chloroethyl) phosphate (TCEP), low (2.5 uM) or high (25 uM) concentrations of tris(2-chloroisopropyl) phosphate (TCIPP). For control purposes, cells were exposed to 0.1% DMSO alone. Treatment lasted for 72 hours. Treatments were done in triplicate for each condition involving separate cell seeding, cell growth, treatments and RNA extractions per triplicate. RNA was isolated with Trizol (Invitrogen, USA) and RNeasy Kit (Qiagen, GER). Libraries were prepared with the TruSeq Stranded mRNA Sample Preparation Kit (Illumina, USA). 50bp long paired-ends reads were sequenced using the HiSeq(R) 1500 platform (Illumina, USA). Alignment, mapping and annotation of sequenced reads were performed using the CLC Genomics Workbench (CLC Bio, Aarhus, Denmark). Samples were normalized by quantile normalization before being mapped and annotated using the human reference hg19 genome.
A toxicogenomics approach to screen chlorinated flame retardants tris(2-chloroethyl) phosphate and tris(2-chloroisopropyl) phosphate for potential health effects.
Specimen part, Cell line, Treatment, Subject
View SamplesTris (2-butoxyethyl) phosphate (TBOEP) is a compound produced at high volume that is used as both a flame retardant and a plasticizer. It is persistent and bioaccumulative, yet little is known of its toxicological modes of action. Such insight may aid risk assessment in a weight-of-evidence approach supplementing current testing strategies. We used an RNA sequencing approach as an unbiased and sensitive tool to explore potential negative health effects of sub-cytotoxic concentrations of TBOEP on the transcriptome of the human liver hepatocellular carcinoma cell line, HepG2, with the lowest concentration used potentially holding relevance to human physiological levels. Over-representation and gene set enrichment analysis corresponded well and revealed that TBOEP treatments resulted in an upregulation of genes involved in protein and energy metabolism, along with DNA replication. Such increases in cell and macromolecule metabolism could explain the increase in mitochondrial activity at lower TBOEP concentrations. In addition, TBOEP affected a wide variety of biological processes, the most notable one being the general stress response, wound healing. Finally, TBOEP showed effects on steroid hormone biosynthesis and activation, regulation, and potentiation of immune responses, in agreement with other studies. As such, this study is the first study investigating genome-wide changes in gene transcription in response to TBOEP in human cells. Overall design: HepG2 cells were treated with low (2.5 uM) or high (125 uM) concentrations of Tris (2-butoxyethyl) phosphate (TBOEP) in 0.1% DMSO. For control purposes cells were exposed to 0.1% DMSO alone. Treatment lasted for 72 hours. All treatments were conducted in triplicates, involving separate seeding of cells. RNA was isolated with Trizol (Invitrogen, USA) and RNeasy Kit (Qiagen, GER). Libraries were prepared with the TruSeq Stranded mRNA Sample Preparation Kit (Illumina, USA). 50bp long paired-ends reads were sequenced using the HiSeq(R) 1500 platform (Illumina, USA). Alignement to the UCSC hg19 assembly of the human genome, mapping and annotation was performed with CLC Genomics Workbench (CLC Bio, DEN). Samples were normalised by quantile normalisation. Differential expression p-values were generated using Baggerly''s test statistic. These p-values were subsequently corrected with the Benjamini-Hochberg procedure to limit the false discovery rate (FDR) to 5% of the significant genes .
Toxicogenomics of the flame retardant tris (2-butoxyethyl) phosphate in HepG2 cells using RNA-seq.
Cell line, Treatment, Subject
View SamplesThe Wnt/beta-catenin pathway is required for the development of leukemia stem cells in MLL-AF9 AML.
KRas(G12D)-evoked leukemogenesis does not require β-catenin.
Specimen part
View SamplesActivation or maintenance of a leukemia stem cell self-renewal pathway in downstream myeloid cells is an important component of AML development
The Wnt/beta-catenin pathway is required for the development of leukemia stem cells in AML.
Specimen part
View SamplesLeukemias that harbor translocations involving the mixed lineage leukemia gene (MLL) possess unique biological characteristics and often have an unfavorable prognosis. Gene expression analyses demonstrate a distinct profile for MLL-rearranged leukemias with consistent high-level expression of select Homeobox genes including HOXA9. Here, we investigated the effects of HOXA9 suppression in MLL-rearranged and MLL-germline leukemias utilizing RNAi. Gene expression profiling after HOXA9 suppression demonstrated co-downregulation of a program highly expressed in human MLL-AML (this study) and murine MLL-leukemia (Krivtsov et al. 2006) stem cells including HOXA10, MEIS1, PBX3 and MEF2C. Our data indicates an important role for HOXA9 in human MLL-rearranged leukemias, and suggests targeting HOXA9 or downstream programs may be a novel therapeutic option.
HOXA9 is required for survival in human MLL-rearranged acute leukemias.
No sample metadata fields
View SamplesEnhancer activation is a critical step for gene activation. Here we report a novel epigenetic crosstalk at enhancers between the UTX (H3K27 demethylase)-MLL4 (H3K4 methyltransferase) complex and the histone acetyltransferase p300. We demonstrate that UTX, in a demethylase activity-independent manner, facilitates conversion of naïve (unmarked) enhancers in embryonic stem cells to an active (H3K4me1+/H3K27ac+) state by recruiting and coupling the enzymatic functions of MLL4 and p300. Loss of UTX leads to attenuated enhancer activity, characterized by reduced levels of H3K4me1 and H3K27ac as well as impaired transcription. The UTX-MLL4 complex enhances p300-dependent H3K27 acetylation through UTX-dependent stimulation of p300 recruitment while MLL4-mediated H3K4 monomethylation, reciprocally, requires p300 function. Importantly, MLL4-generated H3K4me1 further enhances p300-dependent transcription. This work reveals a previously unrecognized cooperativity among enhancer-associated chromatin modulators, including a unique function for UTX, in establishing an “active enhancer landscape” and defines a mechanism for the joint deposition of H3K4me1 and H3K27ac. Overall design: RNA-sequencing of mouse ES cells.
A UTX-MLL4-p300 Transcriptional Regulatory Network Coordinately Shapes Active Enhancer Landscapes for Eliciting Transcription.
Subject
View SamplesLeukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible.
Transformation from committed progenitor to leukaemia stem cell initiated by MLL-AF9.
No sample metadata fields
View SamplesLeukemia initiating cells (LICs) of acute myeloid leukemia (AML) may arise from self-renewing hematopoietic stem cells (HSCs) and from committed progenitors. However, it remains unclear how leukemia-associated oncogenes instruct LIC formation from cells of different origins and if differentiation along the normal hematopoietic hierarchy is involved. Here, using murine models with the driver mutations MLL-AF9 or MOZ-TIF2, we found that regardless of the transformed cell types, myelomonocytic differentiation to the granulocyte macrophage progenitor (GMP) stage is critical for LIC generation. Blocking myeloid differentiation through disrupting the lineage-restricted transcription factor C/EBPa eliminates GMPs, blocks normal granulopoiesis, and prevents AML development. In contrast, restoring myeloid differentiation through inflammatory cytokines rescues AML transformation. Our findings identify myeloid differentiation as a critical step in LIC formation and AML development, thus guiding new therapeutic approaches.
Hematopoietic Differentiation Is Required for Initiation of Acute Myeloid Leukemia.
Specimen part
View SamplesLeukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible.
Transformation from committed progenitor to leukaemia stem cell initiated by MLL-AF9.
No sample metadata fields
View SamplesLeukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible.
Transformation from committed progenitor to leukaemia stem cell initiated by MLL-AF9.
No sample metadata fields
View Samples