RESUMO
Abnormal WNT signaling increases MYC expression in colon cancer cells in part via oncogenic super-enhancer-(OSE)-mediated gating of the active MYC to the nuclear pore in a poorly understood process. We show here that the principal tenet of the WNT-regulated MYC gating, facilitating nuclear export of the MYC mRNA, is regulated by a CTCF binding site (CTCFBS) within the OSE to confer growth advantage in HCT-116 cells. To achieve this, the CTCFBS directs the WNT-dependent trafficking of the OSE to the nuclear pore from intra-nucleoplasmic positions in a stepwise manner. Once the OSE reaches a peripheral position, which is triggered by a CTCFBS-mediated CCAT1 eRNA activation, its final stretch (≤0.7 µm) to the nuclear pore requires the recruitment of AHCTF1, a key nucleoporin, to the CTCFBS. Thus, a WNT/ß-catenin-AHCTF1-CTCF-eRNA circuit enables the OSE to promote pathological cell growth by coordinating the trafficking of the active MYC gene within the 3D nuclear architecture.
Assuntos
Fator de Ligação a CCCTC/genética , Proteínas de Ligação a DNA/genética , Proteínas Proto-Oncogênicas c-myc/genética , RNA Longo não Codificante/genética , Fatores de Transcrição/genética , Via de Sinalização Wnt/genética , Transporte Ativo do Núcleo Celular , Sítios de Ligação , Fator de Ligação a CCCTC/metabolismo , Núcleo Celular/metabolismo , Colo/metabolismo , Colo/patologia , Citosol/metabolismo , Proteínas de Ligação a DNA/metabolismo , Elementos Facilitadores Genéticos , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Regulação Neoplásica da Expressão Gênica , Genoma Humano , Células HCT116 , Humanos , Ligação Proteica , Proteínas Proto-Oncogênicas c-myc/metabolismo , RNA Longo não Codificante/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Fatores de Transcrição/metabolismo , Sequenciamento Completo do GenomaRESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
WNT signaling activates MYC expression in cancer cells. Here we report that this involves an oncogenic super-enhancer-mediated tethering of active MYC alleles to nuclear pores to increase transcript export rates. As the decay of MYC transcripts is more rapid in the nucleus than in the cytoplasm, the oncogenic super-enhancer-facilitated export of nuclear MYC transcripts expedites their escape from the nuclear degradation system in colon cancer cells. The net sum of this process, as supported by computer modeling, is greater cytoplasmic MYC messenger RNA levels in colon cancer cells than in wild type cells. The cancer-cell-specific gating of MYC is regulated by AHCTF1 (also known as ELYS), which connects nucleoporins to the oncogenic super-enhancer via ß-catenin. We conclude that WNT signaling collaborates with chromatin architecture to post-transcriptionally dysregulate the expression of a canonical cancer driver.
