SOX2 通过改变 c-MYC 超级增强子和启动子区域的共激活因子景观来抑制 c-MYC 转录。

SOX2 represses c-MYC transcription by altering the co-activator landscape of the c-MYC super-enhancer and promoter regions.

机构信息

Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA.

Department of Surgery & Biochemistry & Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA.

出版信息

J Biol Chem. 2024 Sep;300(9):107642. doi: 10.1016/j.jbc.2024.107642. Epub 2024 Aug 8.

Abstract

Our previous studies determined that elevating SOX2 in a wide range of tumor cells leads to a reversible state of tumor growth arrest. Efforts to understand how tumor cell growth is inhibited led to the discovery of a SOX2:MYC axis that is responsible for downregulating c-MYC (MYC) when SOX2 is elevated. Although we had determined that elevating SOX2 downregulates MYC transcription, the mechanism responsible was not determined. Given the challenges of targeting MYC clinically, we set out to identify how elevating SOX2 downregulates MYC transcription. In this study, we focused on the MYC promoter region and an upstream region of the MYC locus that contains a MYC super-enhancer encompassing five MYC enhancers and which is associated with several cancers. Here we report that BRD4 and p300 associate with each of the MYC enhancers in the upstream MYC super-enhancer as well as the MYC promoter region and that elevating SOX2 decreases the recruitment of BRD4 and p300 to these sites. Additionally, we determined that elevating SOX2 leads to increases in the association of SOX2 and H3K27me3 within the MYC super-enhancer and the promoter region of MYC. Importantly, we conclude that the increases in SOX2 within the MYC super-enhancer precipitate a cascade of events that culminates in the repression of MYC transcription. Together, our studies identify a novel molecular mechanism able to regulate MYC transcription in two distinctly different tumor types and provide new mechanistic insights into the molecular interrelationships between two master regulators, SOX2 and MYC, widely involved in multiple cancers.

摘要

我们之前的研究确定,在广泛的肿瘤细胞中升高 SOX2 会导致肿瘤生长停滞的可逆状态。为了了解肿瘤细胞生长是如何受到抑制的,我们发现了一个 SOX2:MYC 轴,当 SOX2 升高时,该轴负责下调 c-MYC (MYC)。虽然我们已经确定升高 SOX2 下调 MYC 转录,但负责的机制尚未确定。鉴于临床上靶向 MYC 的挑战,我们着手确定如何升高 SOX2 下调 MYC 转录。在这项研究中,我们专注于 MYC 启动子区域和 MYC 基因座的上游区域,该区域包含一个 MYC 超级增强子,包含五个 MYC 增强子,与多种癌症有关。在这里,我们报告 BRD4 和 p300 与上游 MYC 超级增强子中的每个 MYC 增强子以及 MYC 启动子区域结合,并且升高 SOX2 会减少 BRD4 和 p300 对这些位点的募集。此外,我们确定升高 SOX2 会导致 SOX2 和 H3K27me3 在 MYC 超级增强子和 MYC 启动子区域内的结合增加。重要的是,我们得出结论,MYC 超级增强子内 SOX2 的增加引发了一系列事件,最终导致 MYC 转录的抑制。总之,我们的研究确定了一种新的分子机制,能够调节两种截然不同的肿瘤类型中的 MYC 转录,并为 Sox2 和 Myc 这两个广泛参与多种癌症的主要调控因子之间的分子相互关系提供了新的机制见解。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/1fd3/11408076/b0c4ce8a53bb/gr1.jpg

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