Project description:Basal-like breast cancer (BBC) is a highly aggressive form of breast cancer that exhibits extremely high levels of genetic complexity and yet a relatively uniform transcriptional program. We postulate that BBC might be highly dependent on uninterrupted transcription of a key set of genes within this gene expression program and might therefore be exceptionally sensitive to inhibitors of transcription. Utilizing a novel kinase inhibitor and CRISPR/Cas9-mediated gene editing, we show here that basal but not luminal breast cancer cells are exceptionally dependent on CDK7, a transcriptional cyclin-dependent kinase. BBC cells are unique in their dependence on this transcriptional CDK and suffer apoptotic cell death upon CDK7 inhibition. An “Achilles cluster” of BBC-specific genes are extremely sensitive to CDK7 inhibition and frequently associated with super-enhancers. We conclude that CDK7 mediates transcriptional addiction to a vital cluster of genes in BBC and CDK7 inhibition may be useful therapy for this challenging cancer. ChIP-Seq for H3K27ac in basal-like breast cancer and luminal-like breast cancer cell lines
Project description:Cyclin-dependent kinase 7 (CDK7) plays a critical role in the general regulation of RNA polymerase II-mediated transcription. However, the absence of selective CDK7 inhibitors has hindered the ability to investigate the consequences of acute and prolonged inhibition of CDK7 under normal and pathological conditions. Here we present the discovery and characterization of the first covalent CDK7 inhibitor, CDK7-IN-1, that has the unprecedented ability to target a unique cysteine residue located outside of the canonical kinase domain, providing an unanticipated means of achieving selectivity for CDK7 amongst the 20 known CDKs. Cancer cell line profiling indicates that a subset of cancer cell lines, including T-cell acute lymphoblastic leukemia (T-ALL), exhibit 100-fold greater sensitivity to CDK7-IN-1 over other tumor and normal cell lines. Genome-wide expression analysis in Jurkat T-ALL indicates that CDK7-IN-1 disproportionally affects RUNX1 as well as other components of the TAL1 transcriptional network and its targets, downregulating key regulators of transcription and apoptosis critical for the T-ALL state. These oncogenes are encoded by short-lived mRNA transcripts, are associated with super-enhancers, and exhibit a strong dependency on continuous transcription for sustained expression. Therefore, pharmacological modulation of CDK7 kinase activity may define a method for the identification and treatment of tumor types exhibiting extreme dependencies on transcription for maintenance of the oncogenic state. Jurkat cells were treated with various drugs including a covalent inhibitor of CDK7 (CDK7-IN-1), a reversible inhibitor of CDK7 (CDK7-IN-1), Flavopiridol, Actinomycin D, and DMSO controls. Replicates are annotated.
Project description:Small cell lung cancer (SCLC) is an aggressive disease with high mortality. The identification of effective pharmacological strategies to target SCLC biology represents an urgent need. Using a high-throughput cellular screen of a diverse chemical library we observe that SCLC is sensitive to transcription-targeting drugs, and in particular to THZ1, a newly identified covalent inhibitor of cyclin-dependent kinase 7 (CDK7). We find that expression of super-enhancer associated transcription factor genes including MYC family proto-oncogenes and neuroendocrine lineage-specific factors are highly vulnerability to THZ1 treatment. We propose that downregulation of these transcription factors contributes, in part, to SCLC sensitivity to transcriptional inhibitors and that THZ1 represents a novel treatment paradigm for targeted SCLC therapy. ChIP-Seq for H3K27ac in small cell lung cancer lines
Project description:Super-enhancers and stretch enhancers (SEs) drive expression of genes that play prominent roles in normal and disease cells, but the functional importance of these clustered enhancer elements is poorly understood, so it is not clear why genes key to cell identity have evolved regulation by such elements. Here we show that super-enhancers consist of functional constituent units that concentrate multiple developmental signaling pathways at key pluripotency genes in embryonic stem cells and confer responsiveness to signaling of their associated genes. Cancer cells frequently acquire SEs at genes that promote tumorigenesis, and we show that these genes are especially sensitive to perturbation of oncogenic signaling pathways. Super-enhancers thus provide a platform for signaling pathways to regulate genes that control cell identity during development and tumorigenesis. ChIP-Seq for H3K27ac and RNA Pol II in mouse embryonic stem cells with CRISPR-deleted enhancers
Project description:A unifying characteristic of aggressive cancers is a profound anabolic shift in metabolism to enable sustained proliferation and biomass expansion. The ribosome is centrally situated to sense metabolic states but whether it impacts systems that promote cellular survival is unknown. Here, through integrated chemical-genetic analyses, we find that a dominant transcriptional effect of blocking protein translation in cancer cells is complete inactivation of heat shock factor 1 (HSF1), a multifaceted transcriptional regulator of the heat-shock response and many other cellular processes essential for tumorigenesis. Translational flux through the ribosome reshapes the transcriptional landscape and links the fundamental anabolic processes of protein production and energy metabolism with HSF1 activity. Targeting this link deprives cancer cells of their energy and chaperone armamentarium thereby rendering the malignant phenotype unsustainable. We used ChIP-Seq to examine affect of rocaglates and cycloheximide on HSF1 genomic occupancy in MCF7 and M0-91 cancer cells.
Project description:The overexpression of transcription factors Oct4, Sox2, Klf4, and c-Myc reprograms a somatic nucleus to one that is transcriptionally and epigenetically indistinguishable from an embryonic stem (ES) cell. However, it is still unclear if transcription factors can completely convert the nucleus of a differentiated cell into that of a distantly related cell type such that it maintains complete transcriptional and epigenetic reprogramming in the absence of exogenous factor expression. To test this idea, we screened a library of doxycycline-inducible vectors encoding neural stem cell (NSC)-expressed genes and found that stable, self-maintaining NSC-like cells could be induced under defined growth conditions after transduction of transcription factors. These induced NSCs (iNSCs) were characterized in the absence of exogenous factor induction and were shown to be transcriptionally, epigenetically, and functionally similar to endogenous embryonic cortical NSCs. Importantly, iNSCs could be generated from multiple adult cell types including liver cells and B-cells with genetic rearrangements. Our results show that self-maintaining proliferative neural cells can be induced from non-ectodermal cells by expressing specific combinations of transcription factors. ChIP-seq data from primary neural progenitor cells (Sox2-GFP) and induced neural progenitor cells were generated by deep sequencing using Illumina Hi-Seq 2000.
Project description:Heat-Shock Factor 1 (HSF1), master regulator of the heat-shock response, facilitates malignant transformation, cancer cell survival and proliferation in model systems. The common assumption is that these effects are mediated through regulation of heat-shock protein (HSP) expression. However, the transcriptional network that HSF1 coordinates directly in malignancy and its relationship to the heat-shock response have never been defined. By comparing cells with high and low malignant potential alongside their non-transformed counterparts, we identify an HSF1-regulated transcriptional program specific to highly malignant cells and distinct from heat shock. Cancer-specific genes in this program support oncogenic processes: cell-cycle regulation, signaling, metabolism, adhesion and translation. HSP genes are integral to this program, however, even these genes are uniquely regulated in malignancy. This HSF1 cancer program is active in breast, colon and lung tumors isolated directly from human patients and is strongly associated with metastasis and death. Thus, HSF1 rewires the transcriptome in tumorigenesis, with prognostic and therapeutic implications. ChIP-seq was used to characterize HSF1 binding
Project description:cMyc and Max ChIP-seq analysis in a high MYC expressing small cell lung carcinoma cell line (H2171) and a low MYC expressing small cell lung carcinoma cell line (H128). H2171 cells (expressing high levels of cMyc protein) and H128 cells (expressing low levels of cMyc protein) were used to analyze how cMyc overexpression influences its genome-wide occupancy.
Project description:Retinal pigment epithelial cells are critical for eye function and loss of cell function is linked to age-related blindness. Relatively little is known about the transcriptional regulatory networks in these cells. The datasets presented here are ChIP-seq experiments for RNA polymerase II , transcription factors and histone modifications in human retinal pigment epithelial cells. ChIP-Seq for transcription factors, RNA polymerase, histone modifications and CTCF in retinal pigment epithelial cells