Project description:Clear cell renal cell carcinoma is characterized by loss of function of the von Hippel-Lindau tumor suppressor gene (VHL) and unrestrained activation of hypoxia inducible transcription factors (HIF). Genetic and epigenetic determinants can impact on HIF pathways. A recent genome-wide association study identified single nucleotide polymorphisms (SNPs) in an intergenic region on chromosome 8 that modify the risk of developing renal cancer. The SNPs are located in a putative regulatory region between the oncogenes MYC and PVT1. Using capture C assay and genome editing we show that HIF-binding to this regulatory element is necessary to trans-activate MYC and PVT1 expression specifically in cells of renal tubular origins. Moreover, we demonstrate that the risk associated polymorphisms increase chromatin accessibility and activity as well as binding of HIF to the enhancer. These findings further strengthen the hypothesis that genetic variation at HIF-binding sites modulates the oncogenic transcriptional output of the VHL-HIF axis and provide a functional explanation for disease associated effects of SNPs in ccRCC.
Project description:The transcription factor MYC is overexpressed in most cancers, where it drives multiple hallmarks of cancer progression. MYC is known to promote oncogenic transcription by binding to active promoters. In addition, MYC has also been shown to invade distal enhancers when expressed at oncogenic levels, but this enhancer binding has been proposed to have low gene-regulatory potential. Here, we demonstrate that MYC enhancer binding directly promotes cancer type-specific gene programs predictive of poor patient prognosis. MYC induces transcription of enhancer RNA through recruitment of RNAPII, rather than regulating RNAPII pause-release as is the case at promoters. This is mediated by MYC-induced H3K9 demethylation by KDM3A and acetylation by GCN5, leading to enhancer-specific BRD4 recruitment through its bromodomains, which facilitates RNAPII recruitment. Thus, we propose that MYC drives prognostic cancer type-specific gene programs by promoting RNAPII recruitment to enhancers through induction of an epigenetic switch.
Project description:General activation of hypoxia-inducible factor (HIF) pathways is classically associated with adverse prognosis in cancer and has been proposed to contribute to oncogenic drive. In clear cell renal carcinoma (CCRC) HIF pathways are upregulated by inactivation of the von-Hippel-Lindau tumour suppressor. However HIF-1a and HIF-2a have contrasting effects on experimental tumour progression. To better understand this paradox we examined pan-genomic patterns of HIF DNA binding and associated gene expression in response to manipulation of HIF-1a and HIF-2a and related the findings to CCRC prognosis. Our findings reveal distinct pan-genomic organization of HIF isoform-specific DNA binding at thousands of sites. Overall associations were observed between HIF-1a-specific binding, and genes associated with favourable prognosis and between HIF-2a-specific binding and adverse prognosis. However within each isoform-specific set, individual gene associations were heterogeneous in sign and magnitude, suggesting that activation of each HIF-a isoform contributes a highly complex mix of pro- and anti-tumorigenic effects ChIP and RNASeq of HIF-1a and HIF-2a transfection in 786-O cell lines
Project description:The oncogenic potential of cancer-associated genetic alterations displays strong tissue-selectivity, the origins of which remain poorly understood. Here, we demonstrate that the lineage transcription factor PAX8 is essential for oncogenic signaling downstream of the most common genetic alterations causing clear cell renal cell carcinoma (ccRCC). Through interaction at a distal enhancer element PAX8 facilitates CCND1 expression by HIF2A, an oncogenic driver that is genetically activated due to VHL loss in ~90% of ccRCCs. PAX8 binding at this enhancer which mediates HIF2A-dependent ccRCC formation is inhibited by the common ccRCC protective allele C at rs7948643. In addition, PAX8 supports MYC expression in ccRCC through HNF1B, another renal lineage factor. Transcriptional lineage factors are thus critical determinants of the tissue-specific cancer risk associated with somatic and inherited genetic variants. Our data also suggest that lineage factors could be targeted for therapeutic inhibition of canonical oncogenic drivers such as MYC and CCND1.
Project description:The oncogenic potential of cancer-associated genetic alterations displays strong tissue-selectivity, the origins of which remain poorly understood. Here, we demonstrate that the lineage transcription factor PAX8 is essential for oncogenic signaling downstream of the most common genetic alterations causing clear cell renal cell carcinoma (ccRCC). Through interaction at a distal enhancer element PAX8 facilitates CCND1 expression by HIF2A, an oncogenic driver that is genetically activated due to VHL loss in ~90% of ccRCCs. PAX8 binding at this enhancer which mediates HIF2A-dependent ccRCC formation is inhibited by the common ccRCC protective allele C at rs7948643. In addition, PAX8 supports MYC expression in ccRCC through HNF1B, another renal lineage factor. Transcriptional lineage factors are thus critical determinants of the tissue-specific cancer risk associated with somatic and inherited genetic variants. Our data also suggest that lineage factors could be targeted for therapeutic inhibition of canonical oncogenic drivers such as MYC and CCND1.
Project description:The oncogenic potential of cancer-associated genetic alterations displays strong tissue-selectivity, the origins of which remain poorly understood. Here, we demonstrate that the lineage transcription factor PAX8 is essential for oncogenic signaling downstream of the most common genetic alterations causing clear cell renal cell carcinoma (ccRCC). Through interaction at a distal enhancer element PAX8 facilitates CCND1 expression by HIF2A, an oncogenic driver that is genetically activated due to VHL loss in ~90% of ccRCCs. PAX8 binding at this enhancer which mediates HIF2A-dependent ccRCC formation is inhibited by the common ccRCC protective allele C at rs7948643. In addition, PAX8 supports MYC expression in ccRCC through HNF1B, another renal lineage factor. Transcriptional lineage factors are thus critical determinants of the tissue-specific cancer risk associated with somatic and inherited genetic variants. Our data also suggest that lineage factors could be targeted for therapeutic inhibition of canonical oncogenic drivers such as MYC and CCND1.
Project description:The oncogenic potential of cancer-associated genetic alterations displays strong tissue-selectivity, the origins of which remain poorly understood. Here, we demonstrate that the lineage transcription factor PAX8 is essential for oncogenic signaling downstream of the most common genetic alterations causing clear cell renal cell carcinoma (ccRCC). Through interaction at a distal enhancer element PAX8 facilitates CCND1 expression by HIF2A, an oncogenic driver that is genetically activated due to VHL loss in ~90% of ccRCCs. PAX8 binding at this enhancer which mediates HIF2A-dependent ccRCC formation is inhibited by the common ccRCC protective allele C at rs7948643. In addition, PAX8 supports MYC expression in ccRCC through HNF1B, another renal lineage factor. Transcriptional lineage factors are thus critical determinants of the tissue-specific cancer risk associated with somatic and inherited genetic variants. Our data also suggest that lineage factors could be targeted for therapeutic inhibition of canonical oncogenic drivers such as MYC and CCND1.
Project description:General activation of hypoxia-inducible factor (HIF) pathways is classically associated with adverse prognosis in cancer and has been proposed to contribute to oncogenic drive. In clear cell renal carcinoma (CCRC) HIF pathways are upregulated by inactivation of the von-Hippel-Lindau tumour suppressor. However HIF-1a and HIF-2a have contrasting effects on experimental tumour progression. To better understand this paradox we examined pan-genomic patterns of HIF DNA binding and associated gene expression in response to manipulation of HIF-1a and HIF-2a and related the findings to CCRC prognosis. Our findings reveal distinct pan-genomic organization of HIF isoform-specific DNA binding at thousands of sites. Overall associations were observed between HIF-1a-specific binding, and genes associated with favourable prognosis and between HIF-2a-specific binding and adverse prognosis. However within each isoform-specific set, individual gene associations were heterogeneous in sign and magnitude, suggesting that activation of each HIF-a isoform contributes a highly complex mix of pro- and anti-tumorigenic effects
Project description:All mammalian cells need oxygen. Inadequate oxygen (hypoxia) triggers cellular responses for survival and the maintenance of homeostasis. A transcription factor, hypoxia-inducible factor (HIF), plays a central role in the hypoxia response; its activity is regulated by the oxygen-dependent degradation of the HIF-1a protein. Despite the ubiquity and importance of hypoxia responses, very little is known about the variation in the global transcriptional response to hypoxia among different cell types and its links to tissue and cell-specific diseases. We analyzed the temporal changes in global transcript levels in response to hypoxia in primary renal proximal tubule epithelial cells (RPTECs), breast epithelial cells, smooth muscle (SMs), and endothelial cells (ECs) with DNA microarrays. The extent of the transcriptional response to hypoxia was greatest in the renal tubule cells. This exaggerated response was associated with a uniquely high level of HIF-1a RNA in renal cells and could be diminished by reducing HIF-1a expression via RNA interference (RNAi). A gene-expression signature of the hypoxia response, derived from our studies of cultured mammary and renal tubular epithelial cells, showed coordinated variation in several human cancers, and was a strong predictor of clinical outcomes in both breast and ovarian cancers. In an analysis of a large, published gene-expression dataset from breast cancers, we found that the prognostic information in the hypoxia signature was virtually independent of that provided by the previously reported wound signature and more predictive of outcomes than any of the clinical parameters in current use. A stimulus or stress experiment design type is where that tests response of an organism(s) to stress/stimulus. e.g. osmotic stress, behavioral treatment Using regression correlation
Project description:High expression of MYC and its target genes define a subset of germinal center B-cell diffuse large B-cell lymphoma (GCB-DLBCL) associated with poor outcomes. Half of these high-grade cases show chromosomal rearrangements between the MYC locus and heterologous enhancer-bearing loci, while focal deletions of the adjacent non-coding gene PVT1 are enriched in MYC-intact cases. To identify genomic drivers of MYC activation, we used high-throughput CRISPR-interference (CRISPRi) profiling of candidate enhancers in the MYC locus and rearrangement partner loci in GCB-DLBCL cell lines and mantle cell lymphoma (MCL) comparators that lacked common rearrangements between MYC and immunoglobulin (Ig) loci. Rearrangements between MYC and non-Ig loci were associated with unique dependencies on specific enhancer subunits within those partner loci. Notably, fitness dependency on enhancer modules within the BCL6 super-enhancer (BCL6-SE) cluster regulated by a transcription factor complex of MEF2B, POU2F2, and POU2AF1 was higher in cell lines bearing a recurrent MYC::BCL6-SE rearrangement. In contrast, GCB-DLBCL cell lines without MYC rearrangement were highly dependent on a previously uncharacterized 3’ enhancer within the MYC locus itself (GCBME-1), that is regulated in part by the same triad of factors. GCBME-1 is evolutionarily conserved and active in normal germinal center B cells in humans and mice, suggesting a key role in normal germinal center B cell biology. Finally, we show that the PVT1 promoter limits MYC activation by either native or heterologous enhancers and demonstrate that this limitation is bypassed by 3’ rearrangements that remove PVT1 from its position in cis with the rearranged MYC gene.