BRD4 inhibition impairs DNA mismatch repair, induces mismatch repair mutation signatures and creates therapeutic vulnerability to immune checkpoint blockade in MMR-proficient tumors.
BRD4 inhibition impairs DNA mismatch repair, induces mismatch repair mutation signatures and creates therapeutic vulnerability to immune checkpoint blockade in MMR-proficient tumors.
复制标题
DOI：
10.1136/jitc-2022-006070
复制
发表时间：
2023-04
影响因子：
10.9
通讯作者：
中科院分区：
文献类型：
--
作者：
错配修复缺陷(DMMR)是公认的免疫检查点阻断(ICB)应答的生物标志物。为了使肿瘤对ICB敏感，人们迫切需要将精通MMR的(PMMR)转化为dMMR表型的策略。含4溴结构域(BRD4)抑制物与ICB联合应用具有良好的抗肿瘤作用。然而，其背后的机制仍不清楚。在这里，我们发现BRD4抑制在癌症中诱导了持续的dMMR表型。我们通过对肿瘤基因组图谱和临床蛋白质组肿瘤分析联盟数据的生物信息学分析，以及对卵巢癌标本免疫组织化学(IHC)评分的统计分析，证实了BRD4与错配修复(MMR)的相关性。MMR基因(MLH1、MSH2、MSH6、PMS2)用定量逆转录聚合酶链式反应、免疫印迹和免疫组织化学方法检测。通过外显子全序列测定、RNA测序、MMR检测和次黄嘌呤-鸟嘌呤磷酸核糖基转移酶基因突变检测，证实MMR基因的存在。体外和体内均建立了BRD4i AZD5153耐药模型。通过细胞系染色质免疫沉淀和Cistrome数据浏览器的数据，研究BRD4对MMR基因的转录影响。对ICB的治疗反应在体内得到证实。采用流式细胞仪检测肿瘤免疫微环境标志物：CD4、CD8、TIM-3、FOXP3。我们发现BRD4和MMR基因在转录和翻译方面存在正相关。此外，抑制BRD4转录减少了MMR基因的表达，导致dMMR状态和突变负荷增加。此外，长期暴露于AZD5153在体外和体内都促进了持久的dMMR签名，增强了肿瘤的免疫原性，并增加了对α程序性死亡配体-1治疗的敏感性，尽管存在获得性耐药性。我们发现BRD4抑制抑制了MMR关键基因的表达，抑制了MMR，并在体外和体内增加了dMMR突变特征，使pMMR肿瘤对ICB敏感。重要的是，即使在BRD4抑制剂(BRD4i)耐药的肿瘤模型中，BRD4i对MMR功能的影响保持不变，使肿瘤对ICB敏感。总之，这些数据确定了在pMMR肿瘤中诱导dMMR的策略，并进一步表明，BRD4i敏感和耐药的肿瘤可以从免疫治疗中受益。
Mismatch repair deficiency (dMMR) is a well-recognized biomarker for response to immune checkpoint blockade (ICB). Strategies to convert MMR-proficient (pMMR) to dMMR phenotype with the goal of sensitizing tumors to ICB are highly sought. The combination of bromodomain containing 4 (BRD4) inhibition and ICB provides a promising antitumor effect. However, the mechanisms underlying remain unknown. Here, we identify that BRD4 inhibition induces a persistent dMMR phenotype in cancers. We confirmed the correlation between BRD4 and mismatch repair (MMR) by the bioinformatic analysis on The Cancer Genome Atlas and Clinical Proteomic Tumor Analysis Consortium data, and the statistical analysis on immunohistochemistry (IHC) scores of ovarian cancer specimens. The MMR genes (MLH1, MSH2, MSH6, PMS2) were measured by quantitative reverse transcription PCR, western blot, and IHC. The MMR status was confirmed by whole exome sequencing, RNA sequencing, MMR assay and hypoxanthine-guanine phosphoribosyl transferase gene mutation assay. The BRD4i AZD5153 resistant models were induced both in vitro and in vivo. The transcriptional effects of BRD4 on MMR genes were investigated by chromatin immunoprecipitation among cell lines and data from the Cistrome Data Browser. The therapeutic response to ICB was testified in vivo. The tumor immune microenvironment markers, such as CD4, CD8, TIM-3, FOXP3, were measured by flow cytometry. We identified the positive correlation between BRD4 and MMR genes in transcriptional and translational aspects. Also, the inhibition of BRD4 transcriptionally reduced MMR genes expression, resulting in dMMR status and elevated mutation loads. Furthermore, prolonged exposure to AZD5153 promoted a persistent dMMR signature both in vitro and in vivo, enhancing tumor immunogenicity, and increased sensitivity to α-programmed death ligand-1 therapy despite the acquired drug resistance. We demonstrated that BRD4 inhibition suppressed expression of genes critical to MMR, dampened MMR, and increased dMMR mutation signatures both in vitro and in vivo, sensitizing pMMR tumors to ICB. Importantly, even in BRD4 inhibitors (BRD4i)-resistant tumor models, the effects of BRD4i on MMR function were maintained rendering tumors sensitive to ICB. Together, these data identified a strategy to induce dMMR in pMMR tumors and further, indicated that BRD4i sensitive and resistant tumors could benefit from immunotherapy.
登录
查看更多内容
影响因子：
37.3
作者：
Donati B;Lorenzini E;Ciarrocchi A
通讯作者：
Ciarrocchi A
DOI：
10.1016/j.csbj.2020.03.007
发表时间：
2020-01-01
影响因子：
6
作者：
Li, Lin;Feng, Qiushi;Wang, Xiaosheng
通讯作者：
Wang, Xiaosheng
DOI：
10.1073/pnas.1401182111
发表时间：
2014-05-06
影响因子：
11.1
作者：
Nagel, Zachary D.;Margulies, Carrie M.;Samson, Leona D.
通讯作者：
Samson, Leona D.
影响因子：
5.8
作者：
Saunders, Christopher T.;Wong, Wendy S. W.;Cheetham, R. Keira
通讯作者：
Cheetham, R. Keira
影响因子：
50.3
作者：
McGrail, Daniel J.;Garnett, Jeannine;Lin, Shiaw-Yih
通讯作者：
Lin, Shiaw-Yih