Epigenetic Regulation of Drug Resistance to ABT-199 in B-cell Malignancies

虽然在理解获得性抗性的分子事件方面付出了巨大的努力，但还不是很多。 已经注意到在治疗期间发生了什么，特别是在患者的早期阶段 对药物治疗仍有反应。新型高效选择性小分子BCL-2--文奈德(ABT-199) 最近出现的一种有效的治疗包括MCL在内的血液系统肿瘤的药物。而当 对ABT-199的反应往往是戏剧性的，很少是持久的，而且有很大的需要 延长反应持续时间，延迟或预防耐药(DR)。我们将抗药性模拟为 通过从MCL中建立ABT-199抗性细胞系，并对其适应性分子进行了鉴定 在MCL系和初级样本中重新编程为ABT-199处理。更复杂、更有活力 与我们预期的相比，我们一直检测到一小部分淋巴瘤细胞亚群 选择性ABT-199压力通过进入可逆耐受药物耐受状态(DTP)，导致DTP 扩大人口(DTEP)和最终获得真正的耐药性。我们观察到这些 DTEP细胞可促进存活和克隆生长，并与BH3家族蛋白有关 重新编程。有趣的是，DTEP细胞在长期传代后恢复到药物敏感状态 这种药物支持这些细胞在表观遗传学上重新编程为耐药状态。与一致 这些结果，通过使用药物筛选方法，我们观察到表观遗传调节因子，如BRD4， PRMT5、CDK9和EP300是耐药和耐药进化所必需的，并在其中起重要作用。 最近，针对H3K27的RNA测序(RNA-SEQ)和芯片序列(CHIP-SEQ)被证实为超增强子(SE)。 DTEP细胞的重塑，支持表观遗传调控的SES重塑是 转录重编程与耐药进化。我们的中心假设是转录和 ABT-199治疗后的表观遗传适应性反应和协调性使MCL耐药 和治疗的脆弱性，以防止MCL随后的耐药性演变。这样做的目的是 建议战略性地瞄准表观遗传转录机制，并提供临床前验证 表观基因靶向联合bc1-2拮抗剂治疗MCL这个 研究使我们能够对MCL耐药生物学获得有价值的见解，并揭示一种新的机制-- MCL患者的驱动式治疗。

While enormous effort has gone into understanding the molecular events in acquired resistance, not much attention has been given to what happens during treatment, particularly during the early phase when patients still respond to drug treatment. Venetoclax (ABT-199), a novel potent and selective small-molecule BCL-2 inhibitor, has recently emerged as an effective therapy for hematopoietic tumors including MCL. While responses to ABT-199 can often be dramatic, they are rarely durable, and there is a significant need to improve the duration of response and delay or prevent drug resistance (DR). We modeled drug resistance to ABT-199 by generating ABT-199 resistant cell lines from MCL, and characterized the adaptive molecular reprogramming to ABT-199 treatment in MCL lines and primary samples. More complex and more dynamic than we had anticipated, we consistently detected a small subpopulations of lymphoma cells that evade strong selective ABT-199 pressure by entering a reversible drug tolerant 'persister' state (DTP), leading to DTP expansion population (DTEP) and eventual acquisition of bona fide drug resistance. We observed that these DTEP cells are conferred increased survival, clonogenic growth and are associated with BH3 family protein reprogramming. Intriguingly, DTEP cells revert back to drug sensitive states after long term passage without the drug, supporting that these cells are epigenetically reprogrammed to drug resistant states. Consistent with these results, by using drug screen approaches, we observed that epigenetic regulators such as BRD4, PRMT5, CDK9 and EP300 are required for and contribute to drug tolerance and drug resistance evolution. Most recently, RNA sequencing (RNA-seq) and ChIP-seq against H3K27Acrevealed super-enhancers (SE) remodeling in DTEP cells, supporting that epigenetically regulated SEs remodeling is required for transcriptional reprogramming and drug resistance evolution. Our central hypothesis is that transcriptional and epigenetic adaptive response and coordination in response to ABT-199 treatment confer MCL drug tolerance and therapeutic vulnerability to prevent subsequent drug resistance evolution in MCL. The objective of this proposal is to strategically target epigenetic transcription machinery and provide pre-clinical validation of combination of epigenetically targeting with BCL-2 antagonist as a therapeutic approach against MCL. The study allows us to gain valuable insights into MCL drug resistance biology and uncover a novel mechanism- driven therapy for MCL patients.