Project description:Chromatin regulators have become attractive targets for cancer therapy, but it is unclear why inhibition of these ubiquitous regulators should have gene-specific effects in tumor cells. Here, we investigate how inhibition of the widely expressed transcriptional coactivator BRD4 leads to selective inhibition of the MYC oncogene in multiple myeloma (MM). BRD4 and Mediator were found to co-occupy thousands of enhancers associated with active genes. They also co-occupied a small set of exceptionally large super-enhancers associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impacted genes with super-enhancers, including MYC. Super-enhancers were found at key oncogenic drivers in many other tumor cells. These observations have implications for the discovery of cancer therapeutics directed at components of super-enhancers in diverse tumor types.
Project description:Chromatin regulators have become highly attractive targets for cancer therapy, yet many of these regulators are expressed in a broad range of healthy cells and contribute generally to gene expression. An important conundrum has thus emerged: how can inhibition of a general regulator of gene expression produce selective effects at specific oncogenes? Here we investigate how inhibition of the transcriptional coactivator BRD4 (Bromodomain containing 4) leads to selective inhibition of disease-critical oncogenes in a highly malignant blood cancer, multiple myeloma (MM). We found that BRD4 generally occupies the promoter elements of active genes together with the Mediator coactivator, but remarkably high levels of these two coactivator proteins were associated with a small set of exceptionally large enhancers. These super-enhancers are associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impact genes with super-enhancers, including the c-MYC oncogene. Super-enhancers were found at key oncogenic drivers in many other tumor cells. Thus, super-enhancers can regulate oncogenic drivers in tumor cells, which in some cells can be preferentially disrupted by BRD4 inhibition, which in turn contributes to the selective transcriptional effects observed at these oncogenes. These observations have implications for the discovery of novel cancer therapeutics directed at components of super-enhancers in diverse tumor types. ChIP-Seq for chromatin regulators and RNA Polymerase II in multiple myeloma, glioblastoma multiforme, and small cell lung cancer
Project description:Chromatin regulators have become highly attractive targets for cancer therapy, yet many of these regulators are expressed in a broad range of healthy cells and contribute generally to gene expression. An important conundrum has thus emerged: how can inhibition of a general regulator of gene expression produce selective effects at specific oncogenes? Here we investigate how inhibition of the transcriptional coactivator BRD4 (Bromodomain containing 4) leads to selective inhibition of disease-critical oncogenes in a highly malignant blood cancer, multiple myeloma (MM). We found that BRD4 generally occupies the promoter elements of active genes together with the Mediator coactivator, but remarkably high levels of these two coactivator proteins were associated with a small set of exceptionally large enhancers. These super-enhancers are associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impact genes with super-enhancers, including the c-MYC oncogene. Super-enhancers were found at key oncogenic drivers in many other tumor cells. Thus, super-enhancers can regulate oncogenic drivers in tumor cells, which in some cells can be preferentially disrupted by BRD4 inhibition, which in turn contributes to the selective transcriptional effects observed at these oncogenes. These observations have implications for the discovery of novel cancer therapeutics directed at components of super-enhancers in diverse tumor types. Gene expression profiling in multiple myeloma cells after BET-Bromodomain inhibition with JQ1
Project description:Chromatin regulators have become highly attractive targets for cancer therapy, yet many of these regulators are expressed in a broad range of healthy cells and contribute generally to gene expression. An important conundrum has thus emerged: how can inhibition of a general regulator of gene expression produce selective effects at specific oncogenes? Here we investigate how inhibition of the transcriptional coactivator BRD4 (Bromodomain containing 4) leads to selective inhibition of disease-critical oncogenes in a highly malignant blood cancer, multiple myeloma (MM). We found that BRD4 generally occupies the promoter elements of active genes together with the Mediator coactivator, but remarkably high levels of these two coactivator proteins were associated with a small set of exceptionally large enhancers. These super-enhancers are associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impact genes with super-enhancers, including the c-MYC oncogene. Super-enhancers were found at key oncogenic drivers in many other tumor cells. Thus, super-enhancers can regulate oncogenic drivers in tumor cells, which in some cells can be preferentially disrupted by BRD4 inhibition, which in turn contributes to the selective transcriptional effects observed at these oncogenes. These observations have implications for the discovery of novel cancer therapeutics directed at components of super-enhancers in diverse tumor types.
Project description:Chromatin regulators have become highly attractive targets for cancer therapy, yet many of these regulators are expressed in a broad range of healthy cells and contribute generally to gene expression. An important conundrum has thus emerged: how can inhibition of a general regulator of gene expression produce selective effects at specific oncogenes? Here we investigate how inhibition of the transcriptional coactivator BRD4 (Bromodomain containing 4) leads to selective inhibition of disease-critical oncogenes in a highly malignant blood cancer, multiple myeloma (MM). We found that BRD4 generally occupies the promoter elements of active genes together with the Mediator coactivator, but remarkably high levels of these two coactivator proteins were associated with a small set of exceptionally large enhancers. These super-enhancers are associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impact genes with super-enhancers, including the c-MYC oncogene. Super-enhancers were found at key oncogenic drivers in many other tumor cells. Thus, super-enhancers can regulate oncogenic drivers in tumor cells, which in some cells can be preferentially disrupted by BRD4 inhibition, which in turn contributes to the selective transcriptional effects observed at these oncogenes. These observations have implications for the discovery of novel cancer therapeutics directed at components of super-enhancers in diverse tumor types.