Effect of CCS1477 treatment on gene expression in NRF2-activated lung cancer cells. Effect of CCS1477 treatment on gene expression in NRF2-activated lung cancer cells

Constitutive activation of NRF2 provides a selective advantage to malignant tumour clones through the hijacking of the NRF2-dependent cytoprotective transcriptional program, which allows the cancer cells to survive and thrive in the chemically stressful tumour niche, whilst also providing resistance to anti-cancer drugs due to the upregulation of xenobiotic metabolizing enzymes and drug efflux pumps. Through a small-molecule epigenetic screen carried out in KEAP1 mutant lung cancer cells, in this study, we identified CCS1477 (Inobrodib) to be an inhibitor of the global NRF2-dependent transcription program. Mechanistically, CCS1477 is able to repress NRF2’s cytoprotective response through the inhibition of its obligate transcriptional activator partner CBP/ p300. Importantly, in addition to repressing NRF2-dependent anti-oxidative stress and xenobiotic metabolizing enzyme gene expression, CCS1477 treatment is also able to reverse the chemoresistance phenotype and re-sensitize NRF2-activated tumour cells to anti-cancer drugs. Furthermore, in co-culture experiments of KEAP1 mutant cancer cells with primary human T cells, CCS1477 treatment suppressed the acquisition of the T cell exhaustion transcriptional state, which should function to augment the anti-cancer immune response. Thus, CCS1477-mediated inhibition of CBP/ p300 represents a novel therapeutic strategy with which to target the currently untreatable tumours with aberrant NRF2 activation. Overall design: RNA-Seq profiling of NRF2-activated lung cancer cells H460, H2023 and wildtype lung cancer cell ABC-1 at 24 hours treatment by 5 mM CCS1477

核因子E2相关因子2（NRF2）的组成型激活，通过劫持依赖NRF2的细胞保护性转录程序，为恶性肿瘤克隆提供了选择性生存优势：癌细胞可借此在化学应激性肿瘤微环境中存活增殖，同时因异生物质代谢酶与药物外排泵的上调，对抗癌药物产生耐药性。本研究在KEAP1突变型肺癌细胞中开展小分子表观遗传筛选，鉴定出CCS1477（Inobrodib）为全局性依赖NRF2的转录程序抑制剂。从机制上而言，CCS1477可通过抑制其必需的转录激活辅因子CBP/p300，阻遏NRF2介导的细胞保护性应答。值得注意的是，除抑制依赖NRF2的抗氧化应激与异生物质代谢酶基因表达外，CCS1477治疗还可逆转化疗耐药表型，使NRF2激活的肿瘤细胞重新对抗癌药物致敏。进一步研究显示，在KEAP1突变癌细胞与原代人T细胞的共培养实验中，CCS1477处理可抑制T细胞耗竭转录状态的获得，从而有望增强抗癌免疫应答。综上，CCS1477介导的CBP/p300抑制代表了一种全新治疗策略，可用于靶向治疗目前尚无有效疗法的NRF2异常激活肿瘤。整体实验设计：对NRF2激活的肺癌细胞H460、H2023以及野生型肺癌细胞ABC-1经5 mM CCS1477处理24小时后，开展RNA测序（RNA-Seq）转录组谱分析。