BRD2 induces drug resistance through activation of the RasGRP1/Ras/ERK signaling pathway in adult T-cell lymphoblastic lymphoma
BRD2 induces drug resistance through activation of the RasGRP1/Ras/ERK signaling pathway in adult T-cell lymphoblastic lymphoma
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DOI：
10.1002/cac2.12039
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发表时间：
2020-05-27
影响因子：
16.2
通讯作者：
Cai, Qing-Qing
中科院分区：
文献类型：
--
作者：
Tian, Xiao-Peng;Cai, Jun;Cai, Qing-Qing
背景 成年T细胞淋巴母细胞淋巴瘤（T-LBL）患者接受高强度化疗方案治疗，但由于频繁发生耐药，疗效仍不理想。我们的目的是探讨成人T-LBL耐药的潜在机制。方法采用基因表达芯片来鉴定化疗耐药和化疗敏感成人T-LBL组织之间差异mRNA表达谱。采用实时 PCR 和免疫组化检测 85 例成人患者新鲜冰冻 T-LBL 组织中含溴结构域蛋白 2 (BRD2) 和 c-Myc 的表达。进行 Ras Pull-down 测定以监测 Ras 激活。使用染色质免疫沉淀分析分析 E2F 转录因子 1 (E2F1)/BRD2 与 RAS 鸟苷释放蛋白 1 (RasGRP1) 启动子区域的结合。通过体内外研究确定BRD2的耐药作用及机制。结果通过基因表达芯片鉴定出成人T-LBL中86个化疗耐药相关基因。其中，BRD2 在化疗耐药的成人 T-LBL 组织中表达上调，并与 85 名成人 T-LBL 患者的无进展生存期和总生存期较差相关。此外，BRD2 在体外和体内均抑制阿霉素 (Dox) 诱导的细胞凋亡。 RasGRP1/Ras/ERK 信号传导的激活可能有助于 BRD2 的 Dox 耐药作用。此外，OTX015（一种溴结构域和额外末端（BET）抑制剂）可逆转 BRD2 的 Dox 耐药作用。患者来源的肿瘤异种移植表明，Dox后序贯使用OTX015显示出优越的治疗效果。结论我们的数据表明，BRD2通过RasGRP1/Ras/ERK信号通路促进成人T-LBL的耐药性。靶向 BRD2 可能是提高成人 T-LBL 治疗效果并延长生存期的新策略。
Background Adult patients with T-cell lymphoblastic lymphoma (T-LBL) are treated with high-intensity chemotherapy regimens, but the response rate is still unsatisfactory because of frequent drug resistance. We aimed to investigate the potential mechanisms of drug resistance in adults with T-LBL.Methods Gene expression microarray was used to identify differential mRNA expression profiles between chemotherapy-resistant and chemotherapy-sensitive adult T-LBL tissues. Real-time PCR and immunohistochemistry were performed to detect the expression of bromodomain-containing protein 2 (BRD2) and c-Myc in fresh-frozen T-LBL tissues from 85 adult patients. The Ras pull-down assay was performed to monitor Ras activation. Chromatin immunoprecipitation assays were used to analyze the binding of E2F transcription factor 1 (E2F1)/BRD2 to the RAS guanyl releasing protein 1 (RasGRP1) promoter region. The drug resistance effect and mechanism of BRD2 were determined by both in vivo and in vitro studies.Results A total of 86 chemotherapy resistance-related genes in adult T-LBL were identified by gene expression microarray. Among them, BRD2 was upregulated in chemotherapy-resistant adult T-LBL tissues and associated with worse progression-free survival and overall survival of 85 adult T-LBL patients. Furthermore, BRD2 suppressed doxorubicin (Dox)-induced cell apoptosis both in vitro and in vivo. The activation of RasGRP1/Ras/ERK signaling might contribute to the Dox resistance effect of BRD2. Besides, OTX015, a bromodomain and extra-terminal (BET) inhibitor, reversed the Dox resistance effect of BRD2. Patient-derived tumor xenograft demonstrated that the sequential use of OTX015 after Dox showed superior therapeutic effects.Conclusions Our data showed that BRD2 promotes drug resistance in adult T-LBL through the RasGRP1/Ras/ERK signaling pathway. Targeting BRD2 may be a novel strategy to improve the therapeutic efficacy and prolong survival of adults with T-LBL.