Removal of introns by pre-mRNA splicing is a critical and in some cases rate-limiting step in mammalian gene expression. Deep sequencing of mouse embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within poly(A) selected transcripts; we classify these as “detained” introns (DIs). We identified thousands of DIs flanking both constitutive and alternatively spliced exons in human and mouse cell lines. Drug inhibition of Clk SR-protein kinase activity triggered rapid splicing changes in a specific set of DIs, about half of which showed increased splicing and half increased intron detention, altering the transcript pool of over 300 genes. These data suggest a widespread mechanism by which a nuclear detained pool of mostly processed pre-mRNAs can be rapidly mobilized in response to stress or homeostatic autoregulation. Overall design: v6.5 mouse embryonic stem cells were untreated, treated with the Clk kinase inhibitor KH-CB19, or treated with DMSO as a negative control. Untreated cells were harvested and a single replicate was sequenced using a custom, ligation-based, stranded library preparation protocol. Treated cells were harvested at time 0 and at 2 hours post-treatment, and poly(A)-selected RNA-seq libraries were made from biological duplicates for each treatment/time, barcoded, and sequenced by strand-specific, paired-end sequencing using the Illumina TruSeq kit.
Detained introns are a novel, widespread class of post-transcriptionally spliced introns.
No sample metadata fields
View SamplesThe epigenetic regulator BMI1 is upregulated in many human malignancies and has been implicated in cell migration, but the impact on autochthonous tumor progression is unexplored. Our analyses of human expression data show that BMI1 levels increase with progression in melanoma. We find that BMI1 expression in melanoma cells does not influence cell proliferation or primary tumor growth. In contrast, BMI1 levels are a key determinant of melanoma metastasis, whereby deletion impairs and overexpression enhances dissemination. Remarkably, BMI1’s pro-metastatic effect reflects enhancement of all stages of the metastatic cascade including invasion, migration, extravasation, adhesion and survival. Additionally, downregulation or upregulation of BMI1 induces sensitivity or resistance to BRAF inhibitor. Consistent with these pleiotropic effects, we find that BMI1 promotes widespread gene expression changes that encompass key hallmarks of the melanoma invasive signature, including activation of TGFß, non-canonical Wnt, EMT and EGF/PDGF pathways. Importantly, for both primary and metastatic melanoma samples, this BMI1-induced signature identifies invasive subclasses of human melanoma and predicts poor patient outcome. Our data yield key insights into melanoma biology and establish BMI1 as a compelling drug target whose inhibition would suppress both metastasis and chemoresistance. Overall design: Three replicates of A375 BMI1 or GFP overexpressing cells.
BMI1 induces an invasive signature in melanoma that promotes metastasis and chemoresistance.
No sample metadata fields
View SamplesMicroRNAs (miRNAs) are a large family of 19-22nt non-coding RNAs that post-transcriptionally regulate their mRNA targets. Computational algorithms predict that over half of all genes are regulated by miRNAs, yet approaches for experimental identification of miRNA binding sites are now emerging. To directly identify endogenous miRNA binding sites, we performed photo-crosslinking immunoprecipitation using antibodies against Ago2, followed by deep-sequencing of RNA tags (CLIP-seq) in mouse embryonic stem cells (mESCs). We also performed parallel CLIP-seq in Dicer null mESCs that lack mature miRNAs, allowing us to define whether the association of Ago2 with the identified sites was mediated by miRNAs. We include the exon-array expression data obtained from three sets of Dicer WT and Dicer Null mESCs.These data are used to determine genes that are differentially expressed between Dicer WT and Dicer Null conditions. Overall design: Six samples (3 Dicer wild-type CLIP RNA libraries representing two biological replicates, 2 Dicer null CLIP RNA libraries, 1 short-RNA library from Dicer wild-type mESCs) were analyzed. Six total mESC samples were analyzed (3 Dicer WT, 3 Dicer Null). Expression values for probesets were summarized into a single per-gene value. The log fold change for Dicer_WT/Dicer_Null was defined as the difference between the mean expression in Dicer WT mESCs and the mean expression in the Dicer Null mESCs.
Genome-wide identification of Ago2 binding sites from mouse embryonic stem cells with and without mature microRNAs.
No sample metadata fields
View SamplesDicer knockout NSCLC mRNAseq profiles the transcriptome, Dicer knockout NSCLC miRseq profiles the miRnome Overall design: DicerHet and DicerKO NSCLC, 2 biological reps each genotype for mRNAseq, 1 biological rep each for miRseq
Global microRNA depletion suppresses tumor angiogenesis.
No sample metadata fields
View SamplesA growing body of literature has proposed cell-autonomous tumor suppressor functions for the mir-143~145 cluster in a variety of human cancers, including lung adenocarcinoma, and has reported therapeutic benefits of delivering mir-143 and mir- 145 to tumors. In contrast to these studies, we found that depletion or forced expression of mir-143 and mir-145 in an autochthonous mouse model of lung adenocarcinoma did not affect tumor development. Surprisingly, we observed that loss of mir-143~145 from the tumor microenvironment significantly reduced tumor burden, indicating a non-cell- autonomous role for these miRNAs in promoting tumorigenesis. By examining the expression patterns of different cell populations isolated in vivo from tumor-bearing lungs using an integrated computational approach, we identified a role for mir-145 in stimulating the proliferation of endothelial cells by downregulating an inhibitory kinase, Camk1d, which prevents mitotic entry. As a consequence, tumors in mir-143~145- deficient animals exhibited diminished hallmarks of neo-angiogenesis, increased apoptosis and their expansion appeared limited by the tumor’s ability to co-opt the alveolar vasculature. These findings show that expression of the mir-143~145 cluster in the tumor stroma promotes rather than suppresses tumorigenesis and cautions against the use of these miRNAs as agents in cancer therapeutics. Overall design: Epcam-positive, CD31-positive, and triple-negative (Epcam-CD31-CD45-) cell populations isolated by flow cytometry from tumor-bearing lungs of K-rasG12D/+, miR-143/145-proficient and -deficient mice. Three independent mice from each genotype were used as biological replicates.
Stromal Expression of miR-143/145 Promotes Neoangiogenesis in Lung Cancer Development.
No sample metadata fields
View SamplesMicroRNAs are a class of short ~22 nucleotide RNAs predicted to regulate nearly half of all protein-coding genes, including many involved in basal cellular processes and organismal development. Although both increases and decreases in the levels of specific miRNAs have been shown to promote tumor development, a global reduction in miRNAs is commonly observed in various human tumors. However, complete loss has not been documented, suggesting an essential function for miRNAs in tumorigenesis. Here we present the finding that transformed or immortalized Dicer-null somatic cells can be isolated readily in vitro, maintain the characteristics of Dicer-expressing controls and remain stably proliferative. Furthermore, Dicer-null cells from a sarcoma cell line, though depleted of miRNAs, are competent for tumor formation. Hence, miRNA levels in cancer may be maintained in vivo by a complex stabilizing selection in the intratumoral environment. Overall design: Small RNAs from tumor cell lines (murine sarcoma KrasG12D, p53 -/-) with and without Dicer (Dicer f/-, Dicer -/-) were analyzed.
Proliferation and tumorigenesis of a murine sarcoma cell line in the absence of DICER1.
Specimen part, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Let-7 represses Nr6a1 and a mid-gestation developmental program in adult fibroblasts.
Specimen part
View SamplesMicroRNAs (miRNAs) are critical to proliferation, differentiation, and development. Here, we characterize gene expression in murine Dicer-null adult mesenchymal stem cell lines, a fibroblast cell type. Loss of Dicer leads to de-repression of let-7 targets at levels that exceed 10-100 fold with increases in transcription. Direct and indirect targets of this miRNA belong to a mid-gestation embryonic program that encompasses known oncofetal genes as well as oncogenes not previously associated with an embryonic state. Surprisingly, this mid-gestation program represents a distinct period that occurs between the pluripotent state of the inner cell mass at embryonic day 3.5 and the induction of let-7, upon differentiation, at embryonic day 10.5. Within this mid-gestation program, we characterize the let-7 target Nr6a1, an embryonic transcriptional repressor that regulates gene expression in adult fibroblasts following miRNA loss. In total, let-7 is required for the continual suppression of embryonic gene expression in adult cells, a mechanism that may underlie its tumor suppressive function. Overall design: mRNAs from adult mesenchymal stem cells (immortalized monoclonal lines of murine MSCs) with and without Dicer (WT: Dicer f/f, KO: Dicer -/-), were analyzed. WT and KO cells were transfected with a nontargeting control siRNA. KO cells were separately transfected with a synthetic let-7g siRNA duplex, or an siRNA targeting Nr6a1.
Let-7 represses Nr6a1 and a mid-gestation developmental program in adult fibroblasts.
Specimen part, Cell line, Subject
View SamplesAnaplastic thyroid carcinoma (ATC) has among the worst prognosis of any solid malignancy. The low incidence of the disease has in part precluded systematic clinical trials and tissue collection, and there has been little progress in developing effective therapies. BRAF and TP53 mutations co-occur in a high proportion of ATC, particularly those associated with a precursor papillary thyroid carcinoma (PTC). In order to develop an adult-onset model of BRAF-mutant anaplastic thyroid carcinoma, we generated a novel thyroid-specific CreER transgenic mouse. We utilize a Cre-regulated BrafV600E mouse and a conditional Trp53 allelic series to demonstrate that p53 constrains progression from papillary to anaplastic thyroid carcinoma. Gene expression and immunohistochemical analyses of murine tumors identified the cardinal features of human ATC including loss of differentiation, local invasion, distant metastasis and rapid lethality. We employed small animal ultrasound imaging to monitor autochthonous tumors, and show that treatment with the selective BRAF inhibitor PLX4720 improved survival, but did not lead to tumor regression or suppress signaling through the MAPK pathway. Combination of PLX4720 and the MEK inhibitor PD0325901 more completely suppressed MAPK pathway activation in mouse and human ATC cell lines, and improved the structural response and survival of ATC-bearing animals. This model expands the limited repertoire of autochthonous models of clinically aggressive thyroid cancer, and these data suggest that small molecule MAPK pathway inhibitors hold clinical promise in the treatment of advanced thyroid carcinoma.
p53 constrains progression to anaplastic thyroid carcinoma in a Braf-mutant mouse model of papillary thyroid cancer.
Specimen part
View SamplesMicroRNAs (miRNAs) are critical to proliferation, differentiation, and development. Here, we characterize gene expression in murine Dicer-null adult mesenchymal stem cell lines, a fibroblast cell type. Loss of Dicer leads to de-repression of let-7 targets at levels that exceed 10-100 fold with increases in transcription. Direct and indirect targets of this miRNA belong to a mid-gestation embryonic program that encompasses known oncofetal genes as well as oncogenes not previously associated with an embryonic state. Surprisingly, this mid-gestation program represents a distinct period that occurs between the pluripotent state of the inner cell mass at embryonic day 3.5 and the induction of let-7, upon differentiation, at embryonic day 10.5. Within this mid-gestation program, we characterize the let-7 target Nr6a1, an embryonic transcriptional repressor that regulates gene expression in adult fibroblasts following miRNA loss. In total, let-7 is required for the continual suppression of embryonic gene expression in adult cells, a mechanism that may underlie its tumor suppressive function.
Let-7 represses Nr6a1 and a mid-gestation developmental program in adult fibroblasts.
Specimen part
View Samples