背景:抑制CDK7,一种有效的转录调节因子,可能为治疗胰腺导管腺癌(PDAC)带来新的希望,具有较大的遗传异质性和丰富的KRAS突变。这项研究旨在探索小分子共价CDK7抑制剂THZ1的不同功效,具有不同KRAS突变的PDAC及其潜在机制。
方法:首先评估CDK7表达与KRAS突变存活的关联。然后在体外和体内研究了THZ1对不同KRAS突变对PDAC的影响。此外,评估了THZ1对不同KRAS突变体PDACs中RNA聚合酶II(RNAPOLII)基因转录和磷酸化的影响,使用染色质免疫沉淀测序评估THZ1对超级增强子活性的影响。最后,分析了THZ1对H3K27ac与PIK3CA的结合以及对PI3K/AKT/mTOR信号传导的影响.
结果:在携带KRAS-G12V突变的PDAC患者中,高CDK7表达与更差的生存率显著相关,但在KRAS-G12D突变的患者中没有。在KRAS-G12VPDAC中,THZ1的凋亡诱导作用明显强于KRAS-G12D癌。THZ1显著抑制KRAS-G12V突变的异种移植瘤生长,抑制作用明显强于KRAS-G12D肿瘤。在微型细胞来源的异种移植(CDX)模型中,THZ1显著抑制KRAS-G12VPDAC,但不抑制KRAS-G12D癌症。THZ1显著抑制RNAPOLII的磷酸化,这种效应在KRAS-G12VPDAC中(尤其是在ser5时)更强。KRAS-G12VPDAC具有更多结合H3K27ac的超级增强剂,在KRAS-G12VPDAC中,THZ1对超级增强子活性的抑制作用也更强。此外,THZ1显著削弱了KRAS-G12VPDAC中H3K27ac与PIK3CA的结合。THZ1显著抑制PI3K/AKT/mTOR通路及其下游标志物,这种效应在KRAS-G12V电池中更强。
结论:在这项产生假设的研究中,与一些具有KRAS-G12D突变的PDAC相比,THZ1可能更有效地选择性抑制某些具有KRAS-G12V突变的PDAC,这可能与其对超级增强子活性和PI3K/AKT/mTOR信号传导的影响有关。我们的发现可能为PDAC的精确管理提供新的关键线索,并为未来的针对性试验设计提供重要证据。
结论:THZ1对携带PDAC的KRAS-G12V突变的影响比G12D突变更强。在KRAS-G12V中,THZ1对RNAPOLII磷酸化的抑制作用强于KRAS-G12DPDAC。在KRAS-G12VPDAC中,THZ1对超级增强子活性和H3K27ac与PIK3CA结合的抑制更强。在KRAS-G12VPDAC中,THZ1对PI3K/AKT/mTOR通路的抑制作用更强。
Inhibition of CDK7, a potent transcription regulator, may bring new hope for treating pancreatic ductal adenocarcinoma (PDAC), which is featured by large genetic heterogeneity and abundant KRAS mutations. This investigation aimed at exploring the discrepant efficacies of THZ1, a small-molecule covalent CDK7 inhibitor, on PDACs with different KRAS mutations and the underlying mechanisms.
Associations of CDK7 expression with survival by KRAS mutations were first assessed. Effects of THZ1 on PDAC by different KRAS mutations were then investigated in vitro and in vivo. Moreover, the effects of THZ1 on gene transcription and phosphorylation of RNA polymerase II (RNAPOLII) in different KRAS mutant PDACs were assessed, and the effect of THZ1 on super-enhancer activity was evaluated using chromatin immunoprecipitation sequencing. Lastly, the effects of THZ1 on the binding of H3K27ac to PIK3CA and on the PI3K/AKT/mTOR signalling were analysed.
High CDK7 expression was significantly linked to worse survival within PDAC patients carrying KRAS-G12V mutation but not in those with KRAS-G12D mutation. The apoptosis-inducing effect of THZ1 was markedly stronger in KRAS-G12V PDAC than KRAS-G12D cancer. THZ1 significantly inhibited the growth of xenograft tumour with KRAS-G12V mutation, and the inhibition was markedly stronger than for KRAS-G12D tumour. In mini-cell-derived xenograft (CDX) models, THZ1 significantly suppressed KRAS-G12V PDAC but not KRAS-G12D cancer. THZ1 significantly suppressed the phosphorylation of RNAPOLII, and this effect was stronger in KRAS-G12V PDAC (especially at ser5). KRAS-G12V PDAC had more H3K27ac-binding super-enhancers, and the inhibition of THZ1 on super-enhancer activity was also stronger in KRAS-G12V PDAC. Furthermore, THZ1 significantly weakened the binding of H3K27ac to PIK3CA in KRAS-G12V PDAC. THZ1 significantly suppressed the PI3K/AKT/mTOR pathway and its downstream markers, and this effect was stronger in KRAS-G12V cells.
In this hypothesis-generating
study, THZ1 might selectively inhibit certain PDACs with KRAS-G12V mutation more potently compared with some other PDACs with KRAS-G12D mutation, which might be associated with its effect on super-enhancer activity and the PI3K/AKT/mTOR signalling. Our findings might offer novel key clues for the precise management of PDAC and important evidence for future targeted
trial design.
THZ1 had a stronger effect on PDAC-bearing KRAS-G12V mutation than G12D mutation. Suppressive effect of THZ1 on phosphorylation of RNAPOLII was stronger in KRAS-G12V than KRAS-G12D PDAC. Inhibition of THZ1 on super-enhancer activity and H3K27ac binding to PIK3CA was stronger in KRAS-G12V PDAC. Suppressive effect of THZ1 on PI3K/AKT/mTOR pathway was stronger in KRAS-G12V PDAC.